U.S. patent application number 13/657177 was filed with the patent office on 2013-02-28 for imaging apparatus.
This patent application is currently assigned to PANASONIC CORPORATION. The applicant listed for this patent is Panasonic Corporation. Invention is credited to Kenichi HONJO, Masato MURAYAMA, Dai SHINTANI.
Application Number | 20130050550 13/657177 |
Document ID | / |
Family ID | 40985278 |
Filed Date | 2013-02-28 |
United States Patent
Application |
20130050550 |
Kind Code |
A1 |
SHINTANI; Dai ; et
al. |
February 28, 2013 |
IMAGING APPARATUS
Abstract
An imaging apparatus with improved convenience, which can
perform various types of processing using an imaging device while
performing phase difference detection, is provided. An imaging unit
(1) includes an imaging device (10) for performing photoelectric
conversion to convert light into an electrical signal, the imaging
device (10) configured so that light passes through the imaging
device (10), a phase difference detection unit (20) for receiving
the light having passed through the imaging device (10) to perform
phase difference detection, a focus lens group (72) for adjusting a
focus position, and a body control section (5) for controlling the
imaging device (10) and controlling driving of the focus lens group
(72) at least based on a detection result of the phase difference
detection unit. The body control section (5) performs a focus
operation based on a detection result of the phase difference
detection unit during exposure of the imaging device.
Inventors: |
SHINTANI; Dai; (Osaka,
JP) ; HONJO; Kenichi; (Osaka, JP) ; MURAYAMA;
Masato; (Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Corporation; |
Osaka |
|
JP |
|
|
Assignee: |
PANASONIC CORPORATION
Osaka
JP
|
Family ID: |
40985278 |
Appl. No.: |
13/657177 |
Filed: |
October 22, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12918957 |
Aug 23, 2010 |
8319870 |
|
|
PCT/JP2009/000671 |
Feb 18, 2009 |
|
|
|
13657177 |
|
|
|
|
Current U.S.
Class: |
348/294 ;
348/E3.017 |
Current CPC
Class: |
H01L 27/14621 20130101;
H01L 27/14627 20130101; G02B 7/28 20130101; H04N 5/23212 20130101;
H01L 27/14645 20130101; H04N 9/04515 20180801; H01L 27/14843
20130101; H01L 27/14685 20130101; H04N 5/232122 20180801; H04N
5/232123 20180801; H04N 9/04557 20180801; H04N 5/2253 20130101;
G03B 19/12 20130101; H04N 5/23293 20130101; H01L 27/14623 20130101;
H04N 5/23248 20130101; G03B 13/36 20130101; H01L 27/14618
20130101 |
Class at
Publication: |
348/294 ;
348/E03.017 |
International
Class: |
H04N 3/14 20060101
H04N003/14 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2008 |
JP |
2008-041576 |
Feb 22, 2008 |
JP |
2008-041578 |
Claims
1-20. (canceled)
21. An imaging apparatus, comprising: an imaging section configured
to convert an optical image formed on an imaging plane into an
electrical signal by photoelectric conversion; a distance
measurement section configured to perform distance measurement
using light entering a predetermined region of the imaging plane,
and a control section configured to perform interpolation of the
electrical signal in the predetermined region based on the
electrical signal of a pixel in a vicinity of the predetermined
region.
Description
TECHNICAL FIELD
[0001] The present invention relates to an imaging apparatus
including an imaging device for performing photoelectric
conversion.
BACKGROUND ART
[0002] In recent years, digital cameras that convert an object
image into an electrical signal using an imaging device such as a
charge coupled device (CCD) image sensor, a complementary
metal-oxide semiconductor (CMOS) image sensor or the like,
digitizes the electrical signal, and records the obtained digital
signal have been widely used.
[0003] Single-lens reflex digital cameras include a phase
difference detection section for detecting a phase difference
between object images, and have the phase difference detection AF
function of performing autofocusing (hereinafter also simply
referred to as "AF") by the phase difference detection section.
Since the phase difference detection AF function allows detection
of defocus direction and defocus amount, the moving time of a focus
lens can be reduced, thereby realizing fast-focusing (see, for
example, Patent Document 1). In known single-lens reflex digital
cameras, provided is a movable mirror capable of moving in or out
of an optical path from a lens tube to an imaging device in order
to guide light from an object to a phase difference detection
section.
[0004] In so-called compact digital cameras, the autofocus function
by video AF using an imaging device (see, for example, Patent
Document 2) is employed. Therefore, in compact digital cameras, a
mirror for guiding light from an object to a phase difference
detection section is not provided, thus achieving reduction in the
size of compact digital cameras. In such compact digital cameras,
autofocusing can be performed with light incident on the imaging
device, i.e., with the imaging device being exposed to light. That
is, it is possible to perform various types of processing using the
imaging device, including, for example, obtaining an image signal
from an object image formed on the imaging device to display the
object image on an image display section provided on a back surface
of the camera or to record the object image in a recording section,
while performing autofocusing. In general, this autofocus function
by video AF advantageously has higher accuracy than that of phase
difference detection AF.
CITATION LIST
Patent Document
[0005] PATENT DOCUMENT 1: Japanese Patent Application No.
2007-163545 [0006] PATENT DOCUMENT 2: Japanese Patent Application
No. 2007-135140
SUMMARY OF THE INVENTION
Technical Problem
[0007] However, as in a digital camera according to PATENT DOCUMENT
2, a defocus direction cannot be instantaneously detected by video
AF. For example, when contrast detection AF is employed, a focus is
detected by detecting a contrast peak, but a contrast peak
direction, i.e., a defocus direction cannot be detected unless a
focus lens is shifted to back and forth from its current position,
or the like. Therefore, it takes a longer time to detect a focus.
In view of reducing a time required for detecting a focus, phase
difference detection AF is more advantageous. However, in an
imaging apparatus such as a single-lens reflex digital camera
according to Patent Document 1 employing phase difference detection
AF, a movable mirror has to be moved to be on an optical path from
a lens tube to an imaging device in order to guide light from an
object to a phase difference detection section. Thus, various types
of processing using the imaging device, such as, for example,
exposure of the imaging apparatus cannot be performed while phase
difference detection AF is performed. Also, the movable mirror has
to be moved when an optical path of incident light is switched
between a path toward the phase difference detection section and a
path toward the imaging device. Thus, disadvantageously, a time lag
and noise are generated by moving the movable mirror.
[0008] That is, a known imaging apparatus for performing phase
difference detection AF has been not convenient in relation to
performing various types of processing using the imaging
apparatus.
[0009] In view of the above-described points, the present invention
has been devised, and it is therefore an object of the present
invention to improve the convenience of an imaging apparatus
including an imaging device and a phase difference detection
section in relation to performing various types of processing using
the imaging device and phase difference detection using the phase
difference detection section.
Solution to the Problem
[0010] An imaging apparatus according to the present invention
includes an imaging device for performing photoelectric conversion
to convert light into an electrical signal, the device being
configured so that light passes through the imaging device, a phase
difference detection section for receiving light which has passed
through the imaging device to perform phase difference detection, a
focus lens for adjusting a focus position, and a control section
for controlling the imaging device and controlling driving of the
focus lens at least based on a detection result of the phase
difference detection section to adjust the focus position.
[0011] An imaging apparatus according to another aspect of the
present invention has been devised to realize fast-focusing on an
image object while performing exposure of the imaging device.
Specifically, the imaging apparatus includes an imaging device for
performing photoelectric conversion to convert light into an
electrical signal, the device being configured so that light passes
through the imaging device, a phase difference detection section
for receiving light which has passed through the imaging device to
perform phase difference detection, a focus lens for adjusting a
focus position, and a control section for controlling driving of
the focus lens based on a detection result of the phase difference
detection section to perform a focus operation to focus an image
object on the imaging device, and the control section performs the
focus operation based on the detection result of the phase
difference detection section during exposure of the imaging
device.
Advantages of the Invention
[0012] According to the present invention, an imaging device
configured so that light passes through the imaging device, and a
phase difference detection section for receiving light which has
passed through the imaging device to perform phase difference
detection are provided. Moreover, a control section controls the
imaging device and also controls driving of the focus lens at least
based on a detection result of the phase difference detection
section. Thus, phase difference detection can be performed by the
phase difference detection section using light which has passed
through the imaging device, while causing light to enter the
imaging device to perform various types of processing using the
imaging device. Accordingly, various types of processing using the
imaging device can be performed in parallel with phase difference
detection by the phase difference detection section, or, switching
between various types of processing using the imaging device and
phase difference detection by the phase difference detection
section can be performed quietly and quickly, so that the
convenience of the imaging device can be improved.
[0013] According to another aspect of the present invention, an
imaging device configured so that light passes through the imaging
device, and a phase difference detection section for receiving
light which has passed through the imaging device to perform phase
difference detection are provided. Thus, phase difference detection
can be performed by the phase difference detection section using
light which has passed through the imaging device to focus an image
object on the imaging device, while performing exposure of the
imaging device. Accordingly, the imaging object can be quickly
focused while the imaging device is exposed to light.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a block diagram of a camera according to a first
embodiment of the present invention.
[0015] FIG. 2 is a cross-sectional view of an imaging unit.
[0016] FIG. 3 is a cross-sectional view of an imaging device.
[0017] FIG. 4 is a plan view of the imaging device.
[0018] FIG. 5 is a plan view of a phase difference detection
unit.
[0019] FIG. 6 is a schematic perspective view of an imaging unit
according to a variation.
[0020] FIG. 7 is a cross-sectional view of an imaging device
according to the variation.
[0021] FIG. 8 is a cross-sectional view of an imaging device
according to another variation.
[0022] FIG. 9 is a cross-sectional view illustrating a cross
section of an imaging unit according to the another variation,
which corresponds to FIG. 2.
[0023] FIG. 10 is a cross-sectional view illustrating a cross
section of the imaging unit of the another variation, which is
perpendicular to the cross section corresponding to FIG. 2.
[0024] FIG. 11 is a flowchart of the steps in a shooting operation
using phase difference detection AF before the release button is
pressed all the way down.
[0025] FIG. 12 is a flowchart showing the basic steps in each of
shooting operations including a shooting operation using phase
difference detection AF after the release button is pressed all the
way down.
[0026] FIG. 13 is a flowchart of the steps in a shooting operation
using contrast detection AF before the release button is pressed
all the way down.
[0027] FIG. 14 is a flowchart of the steps in a shooting operation
using hybrid AF before the release button is pressed all the way
down.
[0028] FIG. 15 is a flowchart of the steps in a shooting operation
using phase difference detection AF according to the variation
before the release button is pressed all the way down.
[0029] FIG. 16 is a flowchart of the steps in a shooting operation
using hybrid AF according to the variation before the release
button is pressed all the way down.
[0030] FIG. 17 is a flowchart of the steps in a shooting operation
in a continuous shooting mode before the release button is pressed
all the way down.
[0031] FIG. 18 is a flowchart of the steps in a shooting operation
in the continuous shooting mode after the release button is pressed
all the way down.
[0032] FIG. 19 is a flowchart of the steps in a shooting operation
in a low contrast mode before the release button is pressed all the
way down.
[0033] FIG. 20 is a flowchart of the steps in a shooting operation
of changing AF function according to a type of an interchangeable
lens before the release button is pressed all the way down.
[0034] FIG. 21 is a flowchart of the steps in a shooting operation
in a during-exposure AF shooting mode before the release button is
pressed all the way down.
[0035] FIG. 22 is a flowchart of the steps in a shooting operation
in the during-exposure AF shooting mode after the release button is
pressed all the way down.
[0036] FIG. 23 is a block diagram of a camera according to a second
embodiment of the present invention.
[0037] FIGS. 24(A) through 24(C) are perspective views illustrating
a configuration of a quick return mirror and a shielding plate.
FIG. 24(A) illustrates the quick return mirror in a retracted
position. FIG. 24(B) illustrates the quick return mirror in a
position between the retracted position and a reflection position.
FIG. 24(C) illustrates the quick return mirror in the reflection
position.
[0038] FIG. 25 is a flowchart of the steps in a finder shooting
mode before the release button is pressed all the way down.
[0039] FIG. 26 is a flowchart of the steps in the finder shooting
mode after the release button is pressed all the way down.
[0040] FIG. 27 is a flowchart of the steps in a live view shooting
mode before the release button is pressed all the way down.
[0041] FIG. 28 is a flowchart of the steps in the live view
shooting mode after the release button is pressed all the way
down.
DESCRIPTION OF REFERENCE CHARACTERS
[0042] 1, 401 Imaging Unit [0043] 10, 210, 310 Imaging Device
[0044] 20, 420 Phase Difference Detection Unit (Phase Difference
Detection Section) [0045] 4 Camera Body (Imaging Apparatus Body)
[0046] 40e During-Exposure AF Setting Switch (Setting Switch)
[0047] 44 Image Display Section [0048] 46 Quick Return Mirror
(Movable Mirror) [0049] 47 Shielding Plate (Shielding Section)
[0050] 5 Body Control Section (Control Section, Distance Detection
Section) [0051] 6 Finder Optical System [0052] 7 Interchangeable
Lens [0053] 72 Focus Lens Group (Focus Lens) [0054] 73 Aperture
Section (Light Amount Adjustment Section) [0055] 100, 200 Camera
(Imaging Apparatus)
DESCRIPTION OF EMBODIMENTS
[0056] Embodiments of the present invention will be described
hereinafter in detail with reference to the accompanying
drawings.
First Embodiment
[0057] A camera as an imaging apparatus according to a first
embodiment of the present invention will be described.
[0058] As shown in FIG. 1, a camera 100 according to the first
embodiment is a single-lens reflex digital camera with
interchangeable lenses and includes, as major components, a camera
body 4 having a major function as a camera system, and
interchangeable lenses 7 removably attached to the camera body 4.
The interchangeable lenses 7 are attached to a body mount 41
provided on a front face of the camera body 4. The body mount 41 is
provided with an electric contact piece 41a.
[0059] --Configuration of Camera Body--
[0060] The camera body 4 includes the imaging unit 1 for capturing
an object image as a shooting image, a shutter unit 42 for
adjusting an exposure state of the imaging unit 1, an optical low
pass filter (OLPF) 43, serving also as an IR cutter, for removing
infrared light of the object image entering the imaging unit 1 and
reducing the moire phenomenon, an image display section 44,
comprised of a liquid crystal monitor, for displaying a shooting
image, a live view image and various pieces of information, and a
body control section 5. The camera body 4 serves as an imaging
apparatus body.
[0061] In the camera body 4, a power switch 40a for turning on/off
the camera system, a release button 40b operated by a user when the
user performs focusing and releasing operations, and setting
switches 40c and 40f for turning on/off various shooting modes and
functions.
[0062] When the camera system is turned on by the power switch 40a,
power is supplied to each part of the camera body 4 and the
interchangeable lens 7.
[0063] The release button 40b operates as a two-stage switch.
Specifically, autofocusing, AE (Automatic Exposure) or the like,
which will be described later, is performed by pressing the release
button 40b halfway down, and releasing is performed by pressing the
release button 40b all the way down.
[0064] An AF setting switch 40c is a switch for switching an
autofocus function from one to another of three autofocus
functions, which will be described later. The camera body 4 is
configured so that the autofocus function is set to be one of the
three autofocus functions by switching the AF setting switch
40c.
[0065] A continuous shooting mode setting switch 40d is a switch
for setting/canceling a continuous shooting mode, which will be
described later. The camera body 4 is configured so that a shooting
mode can be switched between a normal shooting mode and a
continuous shooting mode by operating the continuous shooting mode
setting switch 40d.
[0066] A during-exposure AF setting switch 40e is a switch for
turning on/off during-exposure AF, which will be described later.
The camera body 4 is configured so that the shooting mode is
switched between a during-exposure AF shooting mode in which
exposure is performed while autofocusing is performed and a normal
shooting mode in which the focus lens group 72 is halted and
autofocusing is not performed while exposure is performed by
operating the during-exposure AF setting switch 40e. The
during-exposure AF setting switch 40e serves as a setting switch
for switching the shooting mode between the during-exposure
focusing shooting mode and the normal shooting mode.
[0067] A macro setting switch 40f is a switch for setting/canceling
a macro shooting mode, which will be described later. The camera
body 4 is configured so that the shooting mode is switched between
the normal shooting mode and the macro shooting mode which is
suitable for close-up shooting by operating the macro setting
switch 40f.
[0068] Clearly, the setting switches 40c-40f may be selection items
in a menu for selecting various camera shooting functions.
[0069] Furthermore, the macro setting switch 40f may be provided to
the interchangeable lens 7.
[0070] The imaging unit 1, which will be described in detail later,
performs photoelectric conversion to convert an object image into
an electrical signal. The imaging unit 1 is configured to be
movable in a plane perpendicular to an optical axis X by a blur
correction unit 45.
[0071] The body control section 5 includes a body microcomputer 50,
a nonvolatile memory 50a, a shutter control section 51 for
controlling driving of the shutter unit 42, an imaging unit control
section 52 for controlling the operation of the imaging unit 1 and
performing A/D conversion of an electrical signal from the imaging
unit 1 to output the converted signal to the body microcomputer 50,
an image reading/recording section 53 for reading image data from,
for example, a card type recording medium or an image storage
section 58 which is an internal memory and recording image data in
the image storage section 58, an image recording control section 54
for controlling the image reading/recording section 53, an image
display control section 55 for controlling display of the image
display section 44, a blur detection section 56 for detecting an
amount of an image blur generated due to shake of the camera body
4, and a correction unit control section 57 for controlling the
blur correction unit 45. The body control section 5 serves as a
control section.
[0072] The body microcomputer 50 is a control device for
controlling core functions of the camera body 4, and performs
control of various sequences. The body microcomputer 50 includes,
for example, a CPU, a ROM and a RAM. Programs stored in the ROM are
read by the CPU, and thereby, the body microcomputer 50 can execute
various functions.
[0073] The body microcomputer 50 is configured to receive input
signals from the power switch 40a, the release button 40b and each
of the setting switches 40c and 40f and output control signals to
the shutter control section 51, the imaging unit control section
52, the image reading/recording section 53, the image recording
control section 54, the correction unit control section 57 and the
like, thereby causing the shutter control section 51, the imaging
unit control section 52, the image reading/recording section 53,
the image recording control section 54, the correction unit control
section 57 and the like to execute respective control operations.
The body microcomputer 50 performs inter-microcomputer
communication with a lens microcomputer 80, which will be described
later.
[0074] For example, according to an instruction of the body
microcomputer 50, the imaging unit control section 52 performs A/D
conversion of an electrical signal from the imaging unit 1 to
output the converted signal to the body microcomputer 50. The body
microcomputer 50 performs predetermined image processing to the
received electrical signal to generate an image signal. Then, the
body microcomputer 50 transmits the image signal to the image
reading/recording section 53, and also instructs the image
recording control section 54 to record and display an image, and
thereby, the image signal is stored in the image storage section 58
and is transmitted to the image display control section 55. The
image display control section 55 controls the image display section
44 based on the transmitted image signal to cause the image display
section 44 to display an image.
[0075] The body microcomputer 50, which will be described in detail
later, is configured to detect an object point distance to the
object via a lens microcomputer 80.
[0076] In the nonvolatile memory 50a, various pieces of information
(unit information) for the camera body 4 are stored. The unit
information includes, for example, model information (unit specific
information) provided to specify the camera body 4, such as name of
a manufacturer, production date and model number of the camera body
4, version information for software installed in the body
microcomputer 50 and firmware update information, information
regarding whether or not the camera body 4 includes sections for
correcting an image blur, such as the blur correction unit 45, the
blur detection section 56 and the like, information regarding a
detection performance of the blur detection section 56, such as a
model number, detection capability and the like, error history and
the like. Such information as listed above may be stored in a
memory section of the body microcomputer 50, instead of the
nonvolatile memory 50a.
[0077] The blur detection section 56 includes an angular velocity
sensor for detecting the movement of the camera body 4 due to hand
shake and the like. The angular velocity sensor outputs a
positive/negative angular velocity signal according to the
direction in which the camera body 4 is moved, using as a reference
an output in a state where the camera body 4 stands still. In this
embodiment, two angular velocity sensors are provided to detect two
directions, i.e., a yawing direction and a pitching direction.
After being subjected to filtering, amplification and the like, the
output angular velocity signal is converted into a digital signal
by the A/D conversion section, and then, is given to the body
microcomputer 50.
[0078] --Configuration of Interchangeable Lens--
[0079] The interchangeable lens 7 serves as an imaging optical
system for forming an object image on the imaging unit 1 in the
camera body 4, and includes, as major components, a focus
adjustment section 7A for performing focusing, an aperture
adjustment section 7B for adjusting an aperture, a lens image blur
correction section 7C for adjusting an optical path to correct an
image blur, and a lens control section 8 for controlling an
operation of the interchangeable lens 7.
[0080] The interchangeable lens 7 is attached to the body mount 41
of the camera body 4 via a lens mount 71. The lens mount 71 is
provided with an electric contact piece 71a which is electrically
connected to the electric contact piece 41a of the body mount 41
when the interchangeable lens 7 is attached to the camera body
4.
[0081] The focus adjustment section 7A is comprised of a focus lens
group 72 for adjusting focus. The focus lens group 72 is movable in
the direction along the optical axis X in a zone from a closest
focus position predetermined as a standard for the interchangeable
lens 7 to an infinite focus position. When a focus position is
detected using a contrast detection method, which will be described
later, the focus lens group 72 has to be movable forward and
backward from a focus position in the direction along the optical
axis X. Therefore, the focus lens group 72 has a lens shift margin
zone which allows the focus lens group 72 to move forward and
backward in the direction along the optical axis X to a further
distance beyond the zone ranging from the closest focus position to
the infinite focus position. Note that the focus lens group 72 does
not have to be comprised of a plurality of lenses, but may be
comprised of a single lens.
[0082] The aperture adjustment section 7B is comprised of an
aperture section 73 for adjusting an aperture. The aperture section
73 serves as a light amount adjustment section.
[0083] The lens image blur correction section 7C includes a blur
correction lens 74, and a blur correction lens driving section 74a
for moving the blur correction lens 74 in a plane perpendicular to
the optical axis X.
[0084] The lens control section 8 includes a lens microcomputer 80,
a nonvolatile memory 80a, a focus lens group control section 81 for
controlling an operation of the focus lens group 72, a focus
driving section 82 for receiving a control signal of the focus lens
group control section 81 to drive the focus lens group 72, an
aperture control section 83 for controlling an operation of the
aperture section 73, a blur detection section 84 for detecting a
blur of the interchangeable lens 7, and a blur correction lens unit
control section 85 for controlling the blur correction lens driving
section 74a.
[0085] The lens microcomputer 80 is a control device for
controlling core functions of the interchangeable lens 7, and is
connected to each component mounted on the interchangeable lens 7.
Specifically, the lens microcomputer 80 includes a CPU, a ROM, and
a RAM and, when programs stored in the ROM are read by the CPU,
various functions can be executed. For example, the lens
microcomputer 80 has the function of setting a lens image blur
correction system (the blur correction lens driving section 74a or
the like) to be a correction possible state or a correction
impossible state, based on a signal from the body microcomputer 50.
Due to the contact of the electric contact piece 71a provided to
the lens mount 71 with the electric contact piece 41a provided to
the body mount 41, the body microcomputer 50 is electrically
connected to the lens microcomputer 80, so that information can be
transmitted/received between the body microcomputer 50 and the lens
microcomputer 80.
[0086] In the nonvolatile memory 80a, various pieces of information
(lens information) for the interchangeable lens 7 are stored. The
lens information includes, for example, model information (lens
specific information) provided to specify the interchangeable lens
7, such as name of a manufacturer, production date and model number
of the interchangeable lens 7, version information for software
installed in the lens microcomputer 80 and firmware update
information, and information regarding whether or not the
interchangeable lens 7 includes sections for correcting an image
blur, such as the blur correction lens driving section 74a, the
blur detection section 84, and the like. If the interchangeable
lens 7 includes sections for correcting an image blur, the lens
information further includes information regarding a detection
performance of the blur detection section 84 such as a model
number, detection capability and the like, information regarding a
correction performance (a lens side correction performance
information) of the blur correction lens driving section 74a such
as a model number, a maximum correctable angle and the like,
version information for software for performing image blur
correction, and the like. Furthermore, the lens information
includes information (lens side power consumption information)
regarding necessary power consumption for driving the blur
correction lens driving section 74a, and information (lens side
driving method information) regarding a method for driving the blur
correction lens driving section 74a. The nonvolatile memory 80a can
store information transmitted from the body microcomputer 50. The
information listed above may be stored in a memory section of the
lens microcomputer 80, instead of the nonvolatile memory 80a.
[0087] The focus lens group control section 81 includes an absolute
position detection section 81a for detecting an absolute position
of the focus lens group 72 in the direction along the optical axis,
and a relative position detection section 81b for detecting a
relative position of the focus lens group 72 in the direction along
the optical axis. The absolute position detection section 81a
detects an absolute position of the focus lens group 72 provided in
a case of the interchangeable lens 7. For example, the absolute
position detection section 81a is comprised of a several-bit
contact-type encoder substrate and a brush, and is capable of
detecting an absolute position. The relative position detection
section 81b cannot detect the absolute position of the focus lens
group 72 by itself, but can detect a moving direction of the focus
lens group 72. The relative position detection section 81b employs,
for example, a two-phase encoder. As for the two-phase encoder, two
rotary pulse encoders, two MR devices, two hall devices, or the
like, for alternately outputting binary signals with an equal pitch
according to the position of the focus lens group 72 in the
direction along the optical axis are provided so that the phases of
their pitches are different from each other. The lens microcomputer
80 calculates the relative position of the focus lens group 72 in
the direction along the optical axis from an output of the relative
position detection section 81b.
[0088] The blur detection section 84 includes an angular velocity
sensor for detecting the movement of the interchangeable lens 7 due
to hand shake and the like. The angular velocity sensor outputs a
positive/negative angular velocity signal according to the
direction in which the interchangeable lens 7 moves, using as a
reference an output in a state where the interchangeable lens 7
stands still. In this embodiment, two angular velocity sensors are
provided to detect two directions, i.e., a yawing direction and a
pitching direction. After being subjected to filtering,
amplification and the like, the output angular velocity signal is
converted into a digital signal by the A/D conversion section, and
then, is given to the lens microcomputer 80.
[0089] A blur correction lens unit control section 85 includes a
moving amount detection section (not shown). The moving amount
detection section is a detection section for detecting an actual
moving amount of the blur correction lens 74. The blur correction
lens unit control section 85 performs feedback control of the blur
correction lens 74 based on an output of the moving amount
detection section.
[0090] An example in which the blur detection sections 56 and 84
and the blur correction units 45 and 74a are provided to both of
the camera body 4 and the interchangeable lens 7 has been
described. However, such blur detection section and blur correction
unit may be provided to either one of the camera body 4 and the
interchangeable lens 7. Also, a configuration in which such blur
detection section and blur correction unit are not provided to
either the camera body 4 or the interchangeable lens 7 may be
employed (in such a configuration, a sequence regarding the
above-described blur correction may be eliminated).
[0091] --Configuration of Imaging Unit--
[0092] As shown in FIG. 2, the imaging unit 1 includes an imaging
device 10 for converting an object image into an electrical signal,
a package 31 for holding the imaging device 10, and a phase
difference detection unit 20 for performing focus detection using
phase difference detection.
[0093] The imaging device 10 is an interline type CCD image sensor,
and, as shown in FIG. 3, includes a photoelectric conversion
section 11 made of a semiconductor material, vertical registers 12,
transfer paths 13, masks 14, color filters 15, and microlenses
16.
[0094] The photoelectric conversion section 11 includes a substrate
11a and a plurality of light receiving sections (also referred to
as "pixels") 11b arranged on the substrate 11a.
[0095] The substrate 11a is made of a Si (silicon) based substrate.
Specifically, the substrate 11a is made of a Si single crystal
substrate or a SOI (silicon-on-insulator wafer). In particular, an
SOI substrate has a sandwich structure of Si thin films and a
SiO.sub.2 thin film, and chemical reaction can be stopped at the
SiO.sub.2 film in etching or like processing. Thus, in terms of
performing stable substrate processing, it is advantageous to use
an SOI substrate.
[0096] Each of the light receiving sections 11b is made of a
photodiode, and absorbs light to generate electrical charges. The
light receiving sections 11b are provided in micro pixel regions
each having a square shape, arranged in matrix on the substrate 11a
(see FIG. 4).
[0097] The vertical register 12 is provided for each light
receiving section 11b, and serves to temporarily store electrical
charges stored in the light receiving section 11b. The electrical
charges stored in the light receiving section 11b are transferred
to the vertical register 12. The electrical charges transferred to
the vertical register 12 are transferred to a horizontal register
(not shown) via the transfer path 13, and then, to an amplifier
(not shown). The electrical charges transferred to the amplifier
are amplified and pulled out as an electrical signal.
[0098] The mask 14 is provided so that the light receiving sections
11b is exposed toward an object while the vertical register 12 and
the transfer path 13 are covered by the mask 14, thereby preventing
light from entering the vertical register 12 and the transfer path
13.
[0099] The color filter 15 and the microlens 16 are provided in
each micro pixel region having a square shape to correspond to an
associated one of the light receiving sections 11b. Each of the
color filters 15 transmits only a specific color, and primary color
filters or complementary color filters are used as the color
filters 15. In this embodiment, as shown in FIG. 4, so-called Bayer
primary color filters are used. That is, assuming that four color
filters 15 arranged adjacent to one another in two rows and two
columns (or in four pixel regions) are a repeat unit throughout the
entire imaging device 10, two green color filters 15g (i.e., color
filters having a higher transmittance in a green visible light
wavelength range than in the other color visible light wavelength
ranges) are arranged in a diagonal direction, and a red color
filter 15r (i.e., a color filter having a higher transmittance in a
red visible light wavelength range than in the other color visible
light wavelength ranges) and a blue color filter 15b (i.e., a color
filter having a higher transmittance in a blue visible light
wavelength range than in the other color visible light wavelength
ranges) are arranged in another diagonal direction. When the entire
set of the color filters 15 is viewed, every second color filter in
the row and column directions is the green color filter 15g.
[0100] The microlenses 16 collect light to cause the light to enter
the light receiving sections 11b. The light receiving sections 11b
can be efficiently irradiated with light by the microlenses 16.
[0101] In the imaging device 10 configured in the above-described
manner, light collected by the microlens 16 enters the color
filters 15r, 15g and 15b. Then, only light having a corresponding
color to each color filter transmits through the color filter, and
an associated one of the light receiving sections 11b is irradiated
with the light. Each of the light receiving sections 11b absorbs
light to generate electrical charges. The electrical charges
generated by the light receiving sections 11b are transferred to
the amplifier via the vertical register 12 and the transfer path
13, and are output as an electrical signal. That is, the amount of
received light having a corresponding color to each color filter is
obtained from each of the light receiving sections 11b as an
output.
[0102] Thus, the imaging device 10 performs photoelectric
conversion at the light receiving sections 11b provided throughout
the entire imaging plane, thereby converting an object image formed
on an imaging plane into an electrical signal.
[0103] In this case, a plurality of light transmitting portions 17
for transmitting irradiation light are formed in the substrate 11a.
The light transmitting portions 17 are formed by cutting, polishing
or etching an opposite surface (hereinafter also referred to as a
"back surface") 11c of the substrate 11a to a surface thereof on
which the light receiving sections 11b are provided to provide
concave-shaped recesses, and each of the light transmitting
portions 17 has a smaller thickness than that of a part of the
substrate 11a located around each of the light transmitting
portions 17. More specifically, each of the light transmitting
portions 17 includes a recess-bottom surface 17a having a smallest
thickness and an inclined surfaces 17b for connecting the
recess-bottom surface 17a with the back surface 11c.
[0104] Each of the light transmitting portions 17 in the substrate
11a is formed to have a thickness which allows light to transmit
through the light transmitting portion 17, so that a part of
irradiation light onto the light transmitting portions 17 is not
converted into electrical charges and is transmitted through the
photoelectric conversion section 11. For example, by forming the
substrate 11a so that each of parts thereof located in the light
transmitting portions 17 has a thickness of 2-3 .mu.m, about 50% of
light having a longer wavelength than that of near infrared light
can be caused to transmit through the light transmitting portions
17.
[0105] Each of the inclined surfaces 17b is set to be at an angle
at which light reflected by the inclined surfaces 17b is not
directed to condenser lenses 21a of the phase difference detection
unit 20, which will be described later, when light is transmitted
through the light transmitting portions 17. Thus, formation of a
non-real image on a line sensor 24a, which will be described later,
is prevented.
[0106] Each of the light transmitting portions 17 serves as a
reduced-thickness portion, which transmits light entering the
imaging device 10, i.e., which allows light entering the imaging
device 10 to pass therethrough. The term "passing" includes the
concept of "transmitting" at least in this specification.
[0107] The imaging device 10 configured in the above-described
manner is held in the package 31 (see FIG. 2). The package 31
serves as a holding portion.
[0108] Specifically, the package 31 includes a flat bottom plate
31a provided with a frame 32, and upright walls 31b provided in
four directions. The imaging device 10 is mounted on the frame 32
to be surrounded by the upright walls 31b in four directions, and
is electrically connected to the frame 32 via bonding wires.
[0109] Moreover, a cover glass 33 is attached to ends of the
upright walls 31b of the package 31 to cover the imaging plane of
the imaging device 10 (on which the light receiving sections 11b
are provided). The imaging plane of the imaging device 10 is
protected by the cover glass 33 from dust and the like being
attached thereto.
[0110] In this case, the same number of openings 31c as the number
of the light transmitting portions 17 are formed in the bottom
plate 31a of the package 31 to pass through the bottom plate 31a
and be located at corresponding positions to the positions of the
light transmitting portions 17 of the imaging device 10. With the
openings 31c provided, light transmitted through the imaging device
10 reaches the phase difference detection unit 20, which will be
described later. The openings 31c serves as light passing
portions.
[0111] In the bottom plate 31a of the package 31, the openings 31c
do not have to be necessarily formed to pass through the bottom
plate 31a. That is, as long as light transmitted through the
imaging device 10 can reach the phase difference detection unit 20,
a configuration in which transparent portions or semi-transparent
portions are formed in the bottom plate 31a, or like configuration
may be employed.
[0112] The phase difference detection unit 20 is provided in the
back surface (an opposite surface to a surface facing an object)
side of the imaging device 10 and receives light transmitted
through the imaging device 10 to perform phase difference
detection. Specifically, the phase difference detection unit 20
converts the received transmitted light into an electrical signal
to be used for distance measurement. The phase difference detection
unit 20 serves as a phase difference detection section.
[0113] As shown in FIGS. 2 and 5, the phase difference detection
unit 20 includes a condenser lens unit 21, a mask member 22, a
separator lens unit 23, a line sensor unit 24, a module frame 25 to
which the condenser lens unit 21, the mask member 22, the separator
lens unit 23 and the line sensor unit 24 are attached. The
condenser lens unit 21, the mask member 22, the separator lens unit
23 and the line sensor unit 24 are arranged in this order along the
thickness direction of the imaging device 10 from the imaging
device 10 side.
[0114] The plurality of condenser lenses 21a integrated into a
single unit form the condenser lens unit 21. The same number of the
condenser lenses 21a as the number of the light transmitting
portions 17 are provided. Each of the condenser lenses 21a collects
incident light. The condenser lens 21a collects light transmitted
through the imaging device 10 and spreading out, and guides the
light to a separator lens 23a of the separator lens unit 23, which
will be described later. Each of the condenser lenses 21a is formed
so that an incident surface 21b of the condenser lens 21a has a
convex shape and a part thereof located close to the incident
surface 21b has a circular column shape.
[0115] Since an incident angle of light entering each of the
separator lenses 23a is reduced by providing the condenser lenses
21a, an aberration of the separator lens 23a can be reduced, and a
distance between object images on a line sensor 24a which will be
described later can be reduced. As a result, the size of each of
the separator lenses 23a and the line sensor 24a can be reduced.
Additionally, when a focus position of an object image from the
imaging optical system greatly diverges from the imaging unit 1
(specifically, greatly diverges from the imaging device 10 of the
imaging unit 1), the contrast of the image is remarkably reduced.
According to this embodiment, however, due to the size-reduction
effect of the condenser lenses 21a and the separator lenses 23a,
reduction in contrast can be prevented, so that a focus detection
range can be increased. If highly accurate phase difference
detection around a focus position is performed, or if the separator
lenses 23a, the line sensors 24a and the like are of sufficient
dimensions, the condenser lens unit 21 does not have to be
provided.
[0116] The mask member 22 is provided between the condenser lens
unit 21 and the separator lens unit 23. In the mask member 22, two
mask openings 22a are formed in a part thereof corresponding to
each of the separator lenses 23a. That is, the mask member 22
divides a lens surface of each of the separator lenses 23a into two
areas, so that only the two areas are exposed toward the condenser
lenses 21a. More specifically, the mask member 22 performs pupil
division to divide light which has been collected by the condenser
lenses 21a into two light beams and causes the two light beams to
enter the separator lens 23a. The mask member 22 can prevent
harmful light from one of adjacent two of the separator lenses 23a
from entering the other one of the adjacent two. Note that the mask
member 22 does not have to be provided.
[0117] The separator lens unit 23 includes a plurality of separator
lenses 23a. In other words, the separator lenses 23a are integrated
into a single unit to form the separator lens unit 23. Like the
condenser lenses 21a, the same number of the separator lens 23a as
the number of light transmitting portions 17 are provided. Each of
the separator lenses 23a forms two identical object images on the
line sensor 24a from two light beams which have passed through the
mask member 22 and has entered the separator lens 23a.
[0118] The line sensor unit 24 includes a plurality of line sensors
24a and a mounting portion 24b on which the line sensors 24a are
mounted. Like the condenser lenses 21a, the same number of the line
sensors 24a as the number of the light transmitting portions 17 are
provided. Each of the line sensors 24a receives an image formed on
an imaging plane and converts the image into an electrical signal.
That is, a distance between the two object images can be detected
from an output of the line sensor 24a, and a shift amount (defocus
amount: Df amount) of a focus of an object image to be formed on
the imaging device 10, and the direction (defocus direction) in
which the focus is shifted can be obtained based on the distance.
(The Df amount, the defocus direction and the like will be
hereinafter also referred to as "defocus information.")
[0119] The condenser lens unit 21, the mask member 22, the
separator lens unit 23 and the line sensor unit 24, configured in
the above-described manner, are provided in the module frame
25.
[0120] The module frame 25 is a member formed to have a frame
shape, and an attaching section 25a is provided on an inner
circumference surface of the module frame 25 to inwardly protrude.
A first attaching portion 25b and a second attaching portion 25c
are formed into a step-like shape at a part of the attaching
section 25a located closer to the imaging device 10. Moreover, a
third attaching portion 25d is formed at a part of the attaching
section 25a located at an opposite side to the imaging device
10.
[0121] The mask member 22 is attached to a side of the second
attaching portion 25c of the module frame 25 located closer to the
imaging device 10, and the condenser lens unit 21 is attached to
the first attaching portion 25b. As shown in FIGS. 2 and 5, the
condenser lens unit 21 and the mask member 22 are formed so that
their edge portions fit in the module frame 25 when the condenser
lens unit 21 and the mask member 22 are attached to the first
attaching portion 25b and the second attaching portion 25c. Thus,
the positions of the condenser lens unit 21 and mask member 22 are
determined relative to the module frame 25.
[0122] The separator lens unit 23 is attached to a side of the
third attaching portion 25d of the module frame 25 located opposite
to the imaging device 10. The third attaching portion 25d is
provided with positioning pins 25e and direction reference pins 25f
each protruding at an opposite side to the condenser lens unit 21
side. The separator lens unit 23 is provided with positioning holes
23b and direction reference holes 23c corresponding respectively to
the positioning pins 25e and the direction reference pins 25f.
Respective diameters of the positioning pins 25e and the
positioning holes 23b are determined so that the positioning pins
25e closely fit in the positioning holes 23b. Respective diameters
of the direction reference pins 25f and the direction reference
holes 23c are determined so that the direction reference pins 25f
loosely fit in the direction reference holes 23c. That is, the
attitude of the separator lens unit 23, such as the direction in
which the separator lens unit 23 is arranged when being attached to
the third attaching portion 25d, is defined by inserting the
positioning pins 25e and the direction reference pins 25f of the
third attaching portion 25d in the positioning holes 23b and the
direction reference holes 23c, and the position of the separator
lens unit 23 is determined relative to the third attaching portion
25d by providing a close fit of the positioning pins 25e with the
positioning holes 23b. Thus, when the attitude and position of the
separator lens unit 23 are determined and then the separator lens
unit 23 is attached, the lens surface of each of the separator
lenses 23a is directed toward the condenser lens unit 21 and faces
to an associated one of the mask openings 22a.
[0123] In the above-described manner, the condenser lens unit 21,
the mask member 22 and the separator lens unit 23 are attached
while being held in positions determined relative to the module
frame 25. That is, the positional relation of the condenser lens
unit 21, the mask member 22 and the separator lens unit 23 are
determined by the module frame 25.
[0124] Then, the line sensor unit 24 is attached to a side of the
module frame 25 located closer to the back surface side of the
separator lens unit 23 (which is the opposite side to the condenser
lens unit 21 side). In this case, the line sensor unit 24 is
attached to the module frame 25 while being held in a position
which allows light transmitted through each of the separator lenses
23a to enter an associated one of the line sensors 24a.
[0125] Thus, the condenser lens unit 21, the mask member 22, the
separator lens unit 23 and the line sensor unit 24 are attached to
the module frame 25, and thereby, the condenser lenses 21a, the
mask member 22, the separator lenses 23a and the line sensor 24a
are arranged to be located at determined positions so that incident
light to the condenser lenses 21a is transmitted through the
condenser lenses 21a to enter the separator lenses 23a via the mask
member 22, and then, the light transmitted through the separator
lenses 23a forms an image on each of the line sensors 24a.
[0126] The imaging device 10 and the phase difference detection
unit 20 configured in the above-described manner are joined
together. Specifically, the imaging device 10 and the phase
difference detection unit 20 are configured so that the openings
31c of the package 31 in the imaging device 10 closely fit the
condenser lenses 21a in the phase difference detection unit 20.
That is, with the condenser lenses 21a in the phase difference
detection unit 20 inserted in the openings 31c of the package 31 in
the imaging device 10, the module frame 25 is bonded to the package
31. Thus, the respective positions of the imaging device 10 and the
phase difference detection unit 20 are determined, and then, the
imaging device 10 and the phase difference detection unit 20 are
joined together while being held in the positions. As described
above, the condenser lenses 21a, the separator lenses 23a and the
line sensors 24a are integrated into a single unit, and then are
attached as a signal unit to the package 31.
[0127] The imaging device 10 and the phase difference detection
unit 20 may be configured so that all of the openings 31c closely
fit the condenser lenses 21a. Alternatively, the imaging device 10
and the phase difference detection unit 20 may be also configured
so that only some of the openings 31c closely fit associated ones
of the condenser lenses 21a, and the rest of the openings 31c
loosely fit associated ones of the condenser lenses 21a. In the
latter case, the imaging device 10 and the phase difference
detection unit 20 are preferably configured so that one of the
condenser lenses 21a and one of the openings 31c located closest to
the center of the imaging plane closely fit each other to determine
positions in the imaging plane, and furthermore, one of the
condenser lenses 21a and one of the openings 31c located most
distant from the center of the imaging plane closely fit each other
to determine circumferential positions (rotation angles) of the
condenser lens 21a and the opening 31c which are located at the
center of the imaging plane.
[0128] As a result of joining the imaging device 10 and the phase
difference detection unit 20 together, the condenser lens 21a, the
pair of the mask openings 22a of the mask member 22, the separator
lens 23a and the line sensor 24a are arranged in the back surface
side of the substrate 11b to correspond to each of the light
transmitting portions 17.
[0129] As described above, relative to the imaging device 10
configured to transmit light therethrough, the openings 31c are
formed in the bottom plate 31a of the package 31 for housing the
imaging device 10, and thereby, light transmitted through the
imaging device 10 is easily caused to reach the back surface side
of the package 31. Also, the phase difference detection unit 20 is
arranged in the back surface side of the package 31, and thus, a
configuration where light transmitted through the imaging device 10
is received at the phase difference detection unit 20 can be easily
realized.
[0130] As long as light transmitted through the imaging device 10
can pass through the openings 31c formed in the bottom plate 31a of
the package 31 to the back surface side of the package 31, any
configuration can be employed for the openings 31c. However, by
forming the openings 31c as through holes, light transmitted
through the imaging device 10 can be caused to reach the back
surface side of the package 31 without attenuating light
transmitted through the imaging device 10.
[0131] With the openings 31c provided to closely fit the condenser
lenses 21a, positioning of the phase difference detection unit 20
relative to the imaging device 10 can be performed using the
openings 31c. If the condenser lenses 21a are not provided, the
separator lenses 23a are configured to fit the openings 31c. Thus,
positioning of the phase difference detection unit 20 relative to
the imaging device 10 can be performed in the same manner.
[0132] In addition, the condenser lenses 21a can be provided to
pass through the bottom plate 31a of the package 31 and reach a
close point to the substrate 11a. Thus, the imaging unit 1 can be
configured as a compact size imaging unit.
[0133] The operation of the imaging unit 1 configured in the
above-described manner will be described hereinafter.
[0134] When light enters the imaging unit 1 from an object, the
light is transmitted through the cover glass 33 and enters the
imaging device 10. The light is collected by the microlenses 16 of
the imaging device 10, and then, is transmitted through the color
filters 15, so that only light of a specific color reaches the
light receiving sections 11b. The light receiving sections 11b
absorbs light to generate electrical charges. Generated electrical
charges are transferred to the amplifier via the vertical register
12 and the transfer path 13, and are output as an electrical
signal. Thus, each of the light receiving sections 11b converts
light into an electrical signal throughout the entire imaging
plane, and thereby, the imaging device 10 converts an object image
formed on the imaging plane into an electrical signal for
generating an image signal.
[0135] In the light transmitting portions 17, a part of irradiation
light to the imaging device 10 is transmitted through the imaging
device 10. The light transmitted through the imaging device 10
enters the condenser lenses 21a which are provided to closely fit
the openings 31c of the package 31. The light transmitted through
each of the condenser lenses 21a and collected is divided into two
light beams, when passing through each pair of mask openings 22a
formed in the mask member 22, and then, enters each of the
separator lenses 23a. Light subjected to pupil division is
transmitted through the separator lens 23a, and identical object
images are formed at two positions on the line sensor 24a. The line
sensor 24a performs photoelectric conversion to generate an
electrical signal from the object images and outputs the electrical
signal.
[0136] In this case, the electrical signal output from the imaging
device 10 is input to the body microcomputer 50 via the imaging
unit control section 52. The body microcomputer 50 obtains
positional information of each of the light receiving sections 11b
and output data corresponding to the amount of light received by
the light receiving section 11b from the entire imaging plane of
the imaging device 10, thereby obtaining an object image formed on
the image plane as an electrical signal.
[0137] In this case, in the light receiving sections 11b, even when
the same light amount is received, the amount of accumulated
charges are different among different lights having different
wavelengths. Thus, outputs from the light receiving sections 11b of
the imaging device 10 are corrected according to the types of the
color filters 15r, 15g and 15b provided to the light receiving
sections 11b. For example, a correction amount for each pixel is
determined so that, when each of a R pixel 11b to which the red
color filter 15r is provided, a G pixel 11b to which the green
color filter 15g is provided, and a B pixel 11b to which the blue
color filter 15b is provided receives the same amount of light
corresponding to the color of each color filter, respective outputs
of the R pixel 11b, the G pixel 11b and the B pixel 11b become at
the same level.
[0138] In this embodiment, the light transmitting portions 17 are
provided in the substrate 11a, and thus, the photoelectric
conversion efficiency is reduced in the light transmitting portions
17, compared to the other portions. That is, even when the pixels
11b receive the same light amount, the amount of accumulated
charges is smaller in ones of the pixels 11b provided in positions
corresponding to the light transmitting portions 17 than in the
other ones of the pixels 11b provided in positions corresponding to
the other portions. Accordingly, when the same image processing as
image processing for output data from the pixels 11b provided in
positions corresponding to the other portions is performed to
output data from the pixels 11b provided in positions corresponding
to the light transmitting portions 17, parts of an image
corresponding to the light transmitting portions 17 might not be
able to be properly shot (for example, shooting image is dark).
Therefore, an output of each of the pixels 11b in the light
transmitting portions 17 is corrected to eliminate or reduce the
influence of the light transmitting portions 17 (for example, by
amplifying an output of each of the pixels 11b in the light
transmitting portions 17 or like method).
[0139] Reduction in output varies depending on the wavelength of
light. That is, as the wavelength increases, the transmittance of
the substrate 11a increases. Thus, depending on the types of the
color filters 15r, 15g and 15b, the amount of light transmitted
through the substrate 11a differs. Therefore, when correction to
eliminate or reduce the influence of the light transmitting
portions 17 on each of the pixels 11b corresponding to the light
transmitting portions 17 is performed, the correction amount is
changed according to the wavelength of light received by each of
the pixels 11b. That is, for each of the pixels 11b corresponding
to the light transmitting portions 17, the correction amount is
increased as the wavelength of light received by the pixel 11b
increases.
[0140] As described above, in each of the pixels 11b, the
correction amount for eliminating or reducing the difference of the
amount of accumulated charges depending on the types of color of
received light is determined. In addition to the correction to
eliminate or reduce the difference of the amount of accumulated
charges depending on the types of color of received light,
correction to eliminate or reduce the influence of the light
transmitting portions 17 is performed. That is, the correction
amount for eliminating or reducing the influence of the light
transmitting portions 17 is a difference between the correction
amount for each of the pixels 11b corresponding to the light
transmitting portions 17 and the correction amount for the pixels
11b which correspond to the other portions than the light
transmitting portions 17 and receive light having the same color.
In this embodiment, different correction amounts are determined for
different colors, based on the following relationship. Thus, a
stable image output can be obtained.
Rk>Gk>Bk [Expression 1]
where Rk is: a difference obtained by deducting the correction
amount for R pixels in the other portions than the light
transmitting portions 17 from the correction amount for R pixels in
the light transmitting portions 17, Gk is: a difference obtained by
deducting the correction amount for G pixels in the other portions
than the light transmitting portions 17 from the correction amount
for G pixels in the light transmitting portions 17, and Bk is: a
difference obtained by deducting the correction amount for B pixels
in the other portions than the light transmitting portions 17 from
the correction amount for B pixels in the light transmitting
portions 17.
[0141] Specifically, since the transmittance of red light having
the largest wavelength is the highest of the transmittances of red,
green and blue lights, the difference in the correction amount for
red pixels is the largest. Also, since the transmittance of blue
light having the smallest wavelength is the lowest of the
transmittances of red, green and blue lights, the difference in the
correction amount for blue pixels is the smallest.
[0142] That is, the correction amount of an output of each of the
pixels 11b in the imaging device 10 is determined based on whether
or not the pixel 11b is provided on a position corresponding to the
light transmitting portion 17, and the type of color of the color
filter 15 corresponding to the pixel 11b. For example, the
correction amount of an output of each of the pixels 11b is
determined so that the white balance and/or intensity is equal for
an image displayed by an output from the light transmitting portion
17 and an image displayed by an output from some other portion than
the light transmitting portion 17.
[0143] The body microcomputer 50 corrects output data from the
light receiving sections 11b in the above-described manner, and
then, generates, based on the output data, an image signal
including positional information, color information and intensity
information in each of the light receiving sections, i.e., the
pixels 11b. Thus, an image signal of an object image formed on the
imaging plane of the imaging device 10 is obtained.
[0144] By correcting an output from the imaging device 10 in the
above-described manner, an object image can be properly shot even
by the imaging device 10 provided with the light transmitting
portions 17.
[0145] An electrical signal output from the line sensor unit 24 is
also input to the body microcomputer 50. The body microcomputer 50
can obtain a distance between two object images formed on the line
sensor 24a, based on the output from the line sensor unit 24, and
then, can detect an in-focus state of an object image formed on the
imaging device 10 from the obtained distance. For example, when an
object image is transmitted through an imaging lens and is
correctly formed on the imaging device 10 (in focus), the two
object images formed on the line sensor 24a are located at
predetermined reference positions with a predetermined reference
distance therebetween. In contrast, when an object image is formed
before the imaging device 10 in the direction along the optical
axis (front focus), the distance between the two object images is
smaller than the reference distance when the object image is in
focus. When an object image is formed behind the imaging device 10
in the direction along the optical axis (back focus), the distance
between the two object images is larger than the reference distance
when the object image is in focus. That is, an output from the line
sensor 24a is amplified, and then, an operation by the arithmetic
circuit obtains information regarding whether or not an object
image has been brought into focus, whether the object is in front
focus or back focus, and the Df amount.
[0146] According to this embodiment, three light transmitting
portions 17 are formed in the imaging device 10, and in the back
surface side of each of the light transmitting portions 17, the
condenser lens 21a of the phase difference detection unit 20, a
pair of mask openings 22a of the mask member 22, the separator lens
23a and the line sensor 24a are provided to be arranged along the
optical axis. That is, the imaging unit 1 (specifically, the
imaging device 10 and the phase difference detection unit 20)
includes three areas (hereinafter also referred to as "phase
difference areas") for detection of a phase difference, in which
the condenser lens 21a, a pair of the mask openings 22a of the mask
member 22, the separator lens 23a and the line sensor 24a are
arranged along the optical axis.
[0147] According to this embodiment, each of the light transmitting
portions 17 is formed in the substrate 11a to have a smaller
thickness than that of a part of the substrate 11a located around
the light transmitting portion 17. However, the present invention
is not limited thereto. For example, the thickness of the entire
substrate 11a may be determined so that a part of irradiation light
onto the substrate 11a in a sufficient amount is transmitted
through the substrate 11a to reach the phase difference detection
unit 20 provided in the back surface side of the substrate 11a. In
such a case, the entire substrate 11a serves as the light
transmitting portion 17.
[0148] Also, according to this embodiment, three light transmitting
portions 17 are formed in the substrate 11a, and three phase
difference areas are provided. However, the present invention is
not limited thereto. The number of each of those components is not
limited to three, but may be any number. For example, as shown in
FIG. 6, nine light transmitting portions 17 may be formed in the
substrate 11a, and accordingly, nine sets of the condenser lens
21a, the separator lens 23a and the line sensor 24a may be
provided, thereby providing nine phase difference areas.
[0149] Furthermore, the imaging device 10 is not limited to a CCD
image sensor but, as shown in FIG. 7, may be a CMOS image
sensor.
[0150] An imaging device 210 is a CMOS image sensor, and includes a
photoelectric conversion section 211 made of a semiconductor
material, transistors 212, signal lines 213, masks 214, color
filters 215, and microlenses 216.
[0151] The photoelectric conversion section 211 includes a
substrate 211a, and light receiving sections 211b each being
comprised of a photodiode. The transistor 212 is provided for each
of the light receiving sections 211b. Electrical charges
accumulated in the light receiving sections 211b are amplified by
the transistors 212 and are output to the outside via the signal
lines 213. Respective configurations of the masks 214, the color
filters 215 and the microlenses 216 are the same as those of the
mask 14, the color filter 15 and the microlens 16.
[0152] As in the CCD image sensor, the light transmitting portions
17 for transmitting irradiation light are formed in the substrate
211a. The light transmitting portions 17 are formed by cutting,
polishing or etching an opposite surface (hereinafter also referred
to as a "back surface") 211c of the substrate 211a to a surface
thereof on which the light receiving sections 211b are provided to
provide concave-shaped recesses, and each of the light transmitting
portions 17 is formed to have a smaller thickness than that of a
part of the substrate 11a located around each of the light
transmitting portions 17.
[0153] In the CMOS image sensor, an amplification rate of the
transistor 212 can be determined for each light receiving section
211b. Therefore, by determining the amplification rate of each
transistor 212 based on whether or not each light receiving section
11b is located at a position corresponding to the light
transmitting portion 17 and the type of color of the color filter
15 corresponding to the light receiving section 11b, parts of an
image corresponding to the light transmitting portions 17 can be
prevented from being not properly shot.
[0154] The configuration of an imaging device through which light
passes is not limited to the configuration in which the light
transmitting portions 17 are provided in the manner described
above. As long as light passes (or is transmitted, as described
above) through the imaging device, any configuration can be
employed. For example, as shown in FIG. 8, an imaging device 310
including light passing portions 318 each of which includes a
plurality of through holes 318a formed in a substrate 311a may be
employed.
[0155] Each of the through holes 318a is formed to pass through the
substrate 311a in the thickness direction of the substrate 311a.
Specifically, regarding pixel regions formed on the substrate 311a
to be arranged in matrix, when it is assumed that four pixel
regions located in two adjacent columns and two adjacent rows are
as a single unit, the light receiving sections 11b are provided in
three of the four pixel regions, and the through hole 318a is
formed in the other one of the four pixels.
[0156] In the three pixel regions of the four pixel regions in
which the light receiving sections 11b are provided, three color
filters 15r, 15g and 15b corresponding to respective colors of the
three light receiving sections 11b are provided. Specifically, a
green color filter 15g is provided in the light receiving section
11b located in a diagonal position to the through hole 318a, a red
color filter 15r is provided in one of the light receiving sections
11b located adjacent to the through hole 318a, and a blue color
filter 15b is provided in the other one of the light receiving
sections 11b located adjacent to the through hole 318a. No color
filter is provided in the pixel region corresponding to the through
hole 318a.
[0157] In the imaging device 10, a pixel corresponding to each
through hole 318a is interpolated using outputs of the light
receiving sections 11b located adjacent to the through hole 318a.
Specifically, interpolation (standard interpolation) of a signal of
the pixel corresponding to the through hole 318a is performed using
an average value of outputs of the four light receiving sections
11b each of which is located diagonally adjacent to the through
hole 318a in the pixel regions and in which the green color filters
15g are provided. Alternatively, in the four light receiving
sections 11b each of which is located diagonally adjacent to the
through hole 318a in the pixel regions and in which the green color
filters 15g are provided, change in output of one pair of the light
receiving sections 11b located adjacent to each other in one
diagonal direction is compared to change in output of the other
pair of the light receiving sections 11b located adjacent to each
other in the other diagonal direction, and then, interpolation
(slope interpolation) of a signal of a pixel corresponding to the
through hole 318a is performed using an average value of outputs of
the pair of the light receiving sections 11b, located diagonally
adjacent, whose change in output is larger, or an average value of
outputs of the pair of the light receiving sections 11b, located
diagonally adjacent, whose change in output is smaller. Assume that
a pixel desired to be interpolated is an edge of a focus object. If
interpolation is performed using the pair of the light receiving
sections 11b whose change in output is larger, the edge is
undesirably caused to be loose. Therefore, the smaller change is
used when each of the changes are equal to or larger than a
predetermined threshold, and the larger change is used when each of
the changes is smaller than the predetermine threshold so that as
small change rate (slope) as possible is employed.
[0158] Then, after performing the interpolation of output data of
the light receiving sections 11b corresponding to the through holes
318a, intensity information and color information for the pixel
corresponding to each of the light receiving sections 11b are
obtained using output data of each of the light receiving sections
11b and, furthermore, predetermined image processing or image
synthesis is performed to generate an image signal.
[0159] Thus, it is possible to prevent parts of an image at the
light passing portions 318 from becoming dark.
[0160] The imaging device 310 configured in the above-described
manner can cause incident light to pass therethrough via the
plurality of the through holes 318a.
[0161] As described above, also by providing, instead of the light
transmitting portions 17, the light passing portions 318 made of
the through holes 318a in the substrate 311a, the imaging device
310 through which light passes can be configured. Moreover, the
imaging device 310 is configured so that light from the plurality
of through holes 318a enters a set of the condenser lens 21a, the
separator lens 23a and the line sensor 24a, and thus,
advantageously, the size of one set of the condenser lens 21a, the
separator lens 23a and the line sensor 24a is not restricted by the
size of pixels. That is, advantageously, the size of one set of the
condenser lens 21a, the separator lens 23a and the line sensor 24a
does not cause any problem in increasing the resolution of the
imaging device 310 by reducing the size of pixels.
[0162] The light passing portions 318 may be provided only in each
part of the substrate 311a corresponding to the condenser lenses
21a and the separator lens 23a of the phase difference detection
unit 20, or may be provided throughout the entire substrate
311a.
[0163] Furthermore, the phase difference detection unit 20 is not
limited to the above-described configuration. For example, as long
as a configuration in which the positions of the condenser lenses
21a and the separator lens 23a are determined relative to the light
transmitting portions 17 of the imaging device 10 is provided, the
condenser lenses 21a do not necessarily have to closely fit the
openings 31c of the package 31. Also, a configuration which does
not include a condenser lens may be employed. Alternatively, a
configuration in which a condenser lens and a separator lens are
integrated into a single unit may be employed.
[0164] As another example, as shown in FIGS. 9 and 10, a phase
difference detection unit 420 in which a condenser lens unit 421, a
mask member 422, a separator lens unit 423 and a line sensor unit
424 are provided so as to be arranged in parallel to the imaging
plane of the imaging device 10 in the back surface side of the
imaging device 10 may be employed.
[0165] Specifically, the condenser lens unit 421 is configured so
that a plurality of condenser lenses 421a are integrated into a
single unit, and includes an incident surface 421b, a reflection
surface 421c and an output surface 421d. That is, in the condenser
lens unit 421, light collected by the condenser lenses 421a is
reflected by the reflection surface 421c at an angle of about 90
degrees, and is output from the output surface 421d. As a result,
the light which has been transmitted through the imaging device 10
and has entered the condenser lens unit 421 is bent substantially
at a right angle, and output from the output surface 421d to be
directed to a separator lens 423a of a separator lens unit 423. The
light which has entered the separator lens 423a is transmitted
through the separator lens 423a, and forms an image on the line
sensor 424a.
[0166] The condenser lens unit 421, the mask member 422, the
separator lens unit 423 and the line sensor unit 424, configured in
the above-described manner, are provided within the module frame
425.
[0167] The module frame 425 is formed to have a box shape, and a
step portion 425a for attaching the condenser lens unit 421 is
provided in the module frame 425. The condenser lens unit 421 is
attached to the step portion 425a so that the condenser lenses 421a
face outward from the module frame 425.
[0168] Moreover, in the module frame 425, an attachment wall potion
425b for attaching the mask member 422 and the separator lens unit
423 is provided so as to upwardly extend at a part facing the
output surface 421d of the condenser lens unit 421. An opening 425c
is formed in the attachment wall potion 425b.
[0169] The mask member 422 is attached to a side of the attachment
wall potion 425b located closer the condenser lens unit 421. The
separator lens unit 423 is attached to a side of the attachment
wall potion 425b located opposite to the condenser lens unit
421.
[0170] Thus, the optical path of light which has passed through the
imaging device 10 is bent in the back surface side of the imaging
device 10, and thus, the condenser lens unit 421, the mask member
422, the separator lens unit 423, the line sensor unit 424 and the
like can be arranged not in the thickness direction of the imaging
device 10 but in parallel to the imaging plane of the imaging
device 10. Therefore, a dimension of the imaging unit 401 in the
thickness direction of the imaging device 10 can be reduced. That
is, an imaging unit 401 can be formed as a compact size imaging
unit 401.
[0171] As described above, as long as light which has passed
through the imaging device 10 can be received in the back surface
side of the imaging device 10 and then phase difference detection
can be performed, a phase difference detection unit having any
configuration can be employed.
[0172] --Operation of Camera--
[0173] The camera 100 configured in the above-described manner has
various shooting modes and functions. The various shooting modes
and functions of the camera 100, and the operation thereof at the
time of each of the modes and functions will be described
hereinafter.
[0174] --AF Function--
[0175] When the release button 40b is pressed halfway down, the
camera 100 performs AF to focus. To perform AF, the camera 100 has
three autofocus functions, i.e., phase difference detection AF,
contrast detection AF and hybrid AF. A user can select one of the
three autofocus functions to be used by operating the AF setting
switch 40c provided to the camera body 4.
[0176] Assuming that a camera system is in a normal shooting mode,
the shooting operation of the camera system using each of the
autofocus functions will be described hereinafter. The "normal
shooting mode" is not a during-exposure AF shooting mode, a macro
shooting mode, or a continuous shooting mode, which will be
described later, but a most basic shooting mode of the camera 100
for normal shooting.
[0177] (Phase Difference Detection AF)
[0178] First, the shooting operation of the camera system using
phase difference detection AF will be described with reference of
FIGS. 11 and 12.
[0179] When the power switch 40a is turned on (Step Sa1),
communication between the camera body 4 and the interchangeable
lens 7 is performed (Step Sa2). Specifically, power is supplied to
the body microcomputer 50 and each of other units in the camera
body 4 to start up the body microcomputer 50. At the same time,
power is supplied to the lens microcomputer 80 and each of other
units in the interchangeable lens 7 via the electric contact pieces
41a and 71a to start up the lens microcomputer 80. The body
microcomputer 50 and the lens microcomputer 80 are programmed to
transmit/receive information to/from each other at start-up time.
For example, lens information for the interchangeable lens 7 is
transmitted from the memory section of the lens microcomputer 80 to
the body microcomputer 50, and then is stored in the memory section
of the body microcomputer 50.
[0180] Subsequently, the body microcomputer 50 positions the focus
lens group 72 at a predetermined reference position which has been
determined in advance by the lens microcomputer 80 (Step Sa3), and
also puts the shutter unit 42 into an open state (Step Sa4) in
parallel with Step Sa3. Then, the process proceeds to Step Sa5, and
the body microcomputer 50 remains in a standby state until the
release button 40b is pressed halfway down by the user.
[0181] Thus, light which has been transmitted through the
interchangeable lens 7 and has entered the camera body 4 passes
through the shutter unit 42, is transmitted through the OLPF 43
serving also as an IR cutter, and then enters the imaging unit 1.
An object image formed in the imaging unit 1 is displayed at the
image display section 44, so that the user can observe an erected
image of an object through the image display section 44.
Specifically, the body microcomputer 50 reads an electrical signal
from the imaging device 10 via the imaging unit control section 52
at constant intervals, and performs predetermined image processing
to the electrical signal that has been read. Then, the body
microcomputer 50 generates an image signal, and controls the image
display control section 55 to cause the image display section 44 to
display a live view image.
[0182] A part of the light which has entered the imaging unit 1 is
transmitted through the light transmitting portions 17 of the
imaging device 10, and enters the phase difference detection unit
20.
[0183] In this case, when the release button 40b is pressed halfway
down (i.e., S1 switch, which is not shown in the drawings, is
turned on) by the user (Step Sa5), the body microcomputer 50
amplifies an output from the line sensor 24a of the phase
difference detection unit 20, and then an operation by the
arithmetic circuit obtains information regarding whether or not an
object image has been brought into focus, whether the object is in
front focus or back focus, and the Df amount (Step Sa6).
[0184] Thereafter, the body microcomputer 50 drives the focus lens
group 72 via the lens microcomputer 80 in the defocus direction by
the Df amount obtained in Step Sa6 (Step Sa7).
[0185] In this case, the phase difference detection unit 20 of this
embodiment includes three sets of the condenser lens 21a, the mask
openings 22a, separator lens 23a, and the line sensor 24a, i.e.,
has three phase difference areas at which phase difference
detection is performed. In phase difference detection in phase
difference detection AF or hybrid AF, the focus lens group 72 is
driven based on an output of the line sensor 24a of one of the sets
corresponding to a distance measurement point arbitrarily selected
by the user.
[0186] Alternatively, an automatic optimization algorithm may be
installed in the body microcomputer 50 beforehand to select one of
the distance measurement points located closest to the camera and
drive the focus lens group 72. Thus, the rate of the occurrence of
focusing on the background of an object instead of the object can
be reduced.
[0187] Application of this selection of the distance measurement
point is not limited to phase difference detection AF. As long as
the focus lens group 72 is driven using the phase difference
detection unit 2, this selection can be employed in AF using any
method.
[0188] Then, whether or not an object image has been brought into
focus is determined (Step Sa8). Specifically, if the Df amount
obtained based on the output of the line sensor 24a is equal to or
smaller than a predetermined value, it is determined that an object
image has been brought into focus (YES), and then, the process
proceeds to Step Sa11. If the Df amount obtained based on the
output of the line sensor 24a is larger than the predetermined
value, it is determined that an object has not been brought into
focus (NO), the process returns to Step Sa6, and Steps Sa6-Sa8 are
repeated.
[0189] In the above-described manner, detection of an in-focus
state and driving of the focus lens group 72 are repeated and, when
the Df amount is equal to or smaller than the predetermined value,
it is determined that an object image has been brought into focus,
and driving of the focus lens group 72 is halted.
[0190] In parallel with phase difference detection AF in Steps
Sa6-Sa8, photometry is performed (Step Sa9), and also image blur
detection is started (Step Sa10).
[0191] Specifically, in Step Sa9, the amount of light entering the
imaging device 10 is measured by the imaging device 10. That is, in
this embodiment, the above-described phase difference detection AF
is performed using light which has entered the imaging device 10
and has been transmitted through the imaging device 10, and thus,
photometry can be performed using the imaging device 10 in parallel
with the above-described phase difference detection AF.
[0192] More specifically, the body microcomputer 50 retrieves an
electrical signal from the imaging device 10 via the imaging unit
control section 52, and measures the intensity of object light
based on the electrical signal, thereby performing photometry.
According to a predetermined algorithm, the body microcomputer 50
determines, from a result of photometry, a shutter speed and an
aperture value, which correspond to a shooting mode at the time of
exposure.
[0193] When photometry is terminated in Step Sa9, image blur
detection is started in Step Sa10. Step Sa9 and Step Sa10 may be
performed in parallel.
[0194] When the release button 40b is pressed halfway down by the
user, various pieces of information for shooting are displayed as
well as a shooting image at the image display section 44, and thus,
the user can confirm each piece of information through the image
display section 44.
[0195] In Step Sa11, the body microcomputer 50 remains in a standby
state until the release button 40b is pressed all the way down
(i.e., a S2 switch, which is not shown in the drawings, is turned
on) by the user. When the release button 40b is pressed all the way
down by the user, the body microcomputer 50 temporarily puts the
shutter unit 42 into a close state (Step Sa12). Then, while the
shutter unit 42 is kept in a close state, electrical charges stored
in the light receiving sections 11b of the imaging device 10 are
transferred for exposure, which will be described later.
[0196] Thereafter, the body microcomputer 50 starts correction of
an image blur based on communication information between the camera
body 4 and the interchangeable lens 7 or any information specified
by the user (Step Sa13). Specifically, the blur correction lens
driving section 74a in the interchangeable lens 7 is driven based
on information of the blur detection section 56 in the camera body
4. According to the intention of the user, any one of (i) use of
the blur detection section 84 and the blur correction lens driving
section 74a in the interchangeable lens 7, (ii) use of the blur
detection section 56 and the blur correction unit 45 in the camera
body 4, and (iii) use of the blur detection section 84 in the
interchangeable lens 7 and the blur correction unit 45 in the
camera body 4 can be selected.
[0197] By starting driving of the image blur correction sections at
a time when the release button 40b is pressed halfway down, the
movement of an object desired to be in focus is reduced, and thus,
phase difference detection AF can be performed with higher
accuracy.
[0198] In parallel with starting of image blur correction, the body
microcomputer 50 stops down the aperture section 73 via the lens
microcomputer 80 so as to attain an aperture value calculated based
on a result of photometry in Step Sa9 (Step Sa14).
[0199] Thus, when the image blur correction is started and the
aperture operation is terminated, the body microcomputer 50 puts
the shutter unit 42 into an open state based on the shutter speed
obtained from the result of photometry in Step Sa9 (Step Sa15). In
the above-described manner, the shutter unit 42 is put into an open
state, so that light from the object enters the imaging device 10,
and electrical charges are stored in the imaging device 10 only for
a predetermined time (Step Sa16).
[0200] The body microcomputer 50 puts the shutter unit 42 into a
close state based on the shutter speed, to terminate exposure (Step
Sa17). After the termination of the exposure, in the body
microcomputer 50, image data is read out from the imaging unit 1
via the imaging unit control section 52 and then, after performing
predetermined image processing to the image data, the image data is
output to the image display control section 55 via the image
reading/recording section 53. Thus, a shooting image is displayed
at the image display section 44. The body microcomputer 50 stores
the image data in the image storage section 58 via the image
recording control section 54 as necessary.
[0201] Thereafter, the body microcomputer 50 terminates image blur
correction (Step Sa18), and releases the aperture section 73 (Step
Sa19). Then, the body microcomputer 50 puts the shutter unit 42
into an open state (Step Sa20).
[0202] When a reset operation is terminated, the lens microcomputer
80 notifies the body microcomputer 50 of the termination of the
reset operation. The body microcomputer 50 waits to receive reset
termination information from the lens microcomputer 80 and also a
series of processings after exposure to be terminated. Thereafter,
the body microcomputer 50 confirms that the release button 40b is
not in a pressed state, and terminates a shooting sequence. Then,
the process returns to Step Sa5, and the body microcomputer 50
remains in a standby state until the release button 40b is pressed
halfway down.
[0203] When the power switch 40a is turned off (Step Sa21), the
body microcomputer 50 moves the focus lens group 72 to a
predetermined reference position which has been determined in
advance (Step Sa22), and puts the shutter unit 42 into a close
state (Step Sa23). Then, respective operations of the body
microcomputer 50 and other units in the camera body 4, and the lens
microcomputer 80 and other units in the interchangeable lens 7 are
halted.
[0204] As described above, in the shooting operation of the camera
system using phase difference detection AF, photometry is performed
by the imaging device 10 in parallel with autofocusing based on the
phase difference detection unit 20. Specifically, the phase
difference detection unit 20 receives light transmitted through the
imaging device 10 to obtain defocus information, and thus, whenever
the phase difference detection unit 20 obtains defocus information,
the imaging device 10 is irradiated with light from an object.
Therefore, photometry is performed using light transmitted through
the imaging device 10 in autofocusing. By doing so, a photometry
sensor does not have to be additionally provided, and photometry
can be performed before the release button 40b is pressed all the
way down, so that a time (hereinafter also referred to as a
"release time lag") from a time point when the release button 40b
is pressed all the way down to a time point when exposure is
terminated can be reduced.
[0205] Moreover, even in a configuration in which photometry is
performed before the release button 40b is pressed all the way
down, by performing photometry in parallel with autofocusing,
increase in processing time after the release button 40b is pressed
halfway down can be prevented. In such a case, a mirror for guiding
light from an object to a photometry sensor or a phase difference
detection unit does not have to be provided.
[0206] Conventionally, a part of light from an object to an imaging
apparatus is directed to a phase difference detection unit provided
outside the imaging apparatus by a mirror or the like. In contrast,
according to this embodiment, an in-focus state can be detected by
the phase difference detection unit 20 using light guided to the
imaging unit 1 as it is, and thus, the in-focus state can be
detected with very high accuracy.
[0207] (Contrast Detection AF)
[0208] Next, the shooting operation of the camera system using
contrast detection AF will be described with reference to FIG.
13.
[0209] When the power switch 40a is turned on (Step Sb1),
communication between the camera body 4 and the interchangeable
lens 7 is performed (Step Sb2), the focus lens group 72 is
positioned at a predetermined reference position (Step Sb3), the
shutter unit 42 is put into an open state (Step Sb4) in parallel
with Step Sb3, and then, the body microcomputer 50 remains in a
standby state until the release button 40b is pressed halfway down
(Step Sb5). The above-described steps are the same as Steps
Sa1-Sa5.
[0210] When the release button 40b is pressed halfway down by the
user (Step Sb5), the body microcomputer 50 drives the focus lens
group 72 via the lens microcomputer 80 (Step Sb6). Specifically,
the body microcomputer 50 drives the focus lens group 72 so that a
focal point of an object image is moved in a predetermined
direction (e.g., toward an object) along the optical axis.
[0211] Then, the body microcomputer 50 obtains a contrast value for
the object image, based on an output from the imaging device 10
received by the body microcomputer 50 via the imaging unit control
section 52, to determine whether or not the contrast value is
reduced (Step Sb7). If the contrast value is reduced (YES), the
process proceeds to Step Sb8. If the contrast value is increased
(NO), the process proceeds to Step Sb9.
[0212] Reduction in contrast value means that the focus lens group
72 is driven in an opposite direction to the direction in which the
object image is brought into focus. Therefore, when the contrast
value is reduced, the focus lens group 72 is reversely driven so
that the focal point of the object image is moved in an opposite
direction to the predetermined direction (e.g., toward the opposite
side to the object) along the optical axis (Step Sb8). Thereafter,
whether or not a contrast peak has been detected is determined
(Step Sb10). If the contrast peak has not been detected (NO),
reverse driving of the focus lens group 72 (Step Sb8) is repeated.
If the contrast peak has been detected (YES), reverse driving of
the focus lens group 72 is halted, and the focus lens group 72 is
moved to a position where the contrast value has reached the peak.
Then, the process proceeds to Step Sa11.
[0213] On the other hand, when the focus lens group 72 is driven in
Step Sb6 and the contrast value is increased, the focus lens group
72 is driven in the direction in which the object image is brought
into focus. Therefore, driving of the focus lens group 72 is
continued (Step Sb9), and whether or not a peak of the contrast
value has been detected is determined (Step Sb10). If the contrast
peak has not been detected (NO), driving of the focus lens group 72
(Step Sb9) is repeated. If the contrast peak has been detected
(YES), driving of the focus lens group 72 is halted, and the focus
lens group 72 is moved to a position where the contrast value has
reached the peak. Then, the process proceeds to Step Sa11.
[0214] As has been described, in the contrast detection method, the
focus lens group 72 is tentatively driven (Step Sb6). Then, if the
contrast value is reduced, the focus lens group 72 is reversely
driven to search for the peak of the contrast value (Steps Sb8 and
Sb10). If the contrast value is increased, driving of the focus
lens group 72 is continued to search for the peak of the contrast
value (Steps Sb9 and Sb10).
[0215] In parallel with this contrast detection AF (Steps
Sb6-Sb10), photometry is performed (Step Sb11), and also image blur
detection is started (Step Sb12). Steps Sb11 and Sb12 are the same
as Step Sa9 and Step Sa11) in phase difference detection AF.
[0216] In Step Sa11, the body microcomputer 50 remains in a standby
state until the release button 40b is pressed all the way down by
the user. A flow of steps after the release button 40b is pressed
all the way down is the same as that of phase difference detection
AF.
[0217] In this contrast detection AF, a contrast peak can be
directly obtained, and thus, as opposed to phase difference
detection AF, various correction operations such as release back
correction (for correcting an out-of-focus state due to the degree
of aperture) and the like are not necessary, so that a highly
accurate focusing performance can be achieved. However, to detect
the peak of a contrast value, the focus lens group 72 has to be
driven until the focus lens group 72 passes through a position
where the contrast value reaches its peak. Accordingly, the focus
lens group 72 has to be moved beyond the position where the
contrast value reaches the peak first and then be moved back to the
position corresponding to the peak of the contrast value, and thus,
a backlash generated in a focus lens group driving system due to
the operation of driving the focus lens group 72 in back and forth
directions has to be removed.
[0218] (Hybrid AF)
[0219] Subsequently, the shooting operation of the camera system
using hybrid AF will be described with reference to FIG. 14.
[0220] Steps (Steps Sc1-Sc5) from the step in which the power
switch 40a is turned on to the step in which the body microcomputer
remains in a standby state until the release button 40b is pressed
halfway down are the same as Steps Sa1-Sa5 in phase difference
detection AF.
[0221] When the release button 40b is pressed halfway down by the
user (Step Sc5), the body microcomputer 50 amplifies an output from
the line sensor 24a of the phase difference detection unit 20, and
then performs an operation by the arithmetic circuit, thereby
determining whether or not an object image has been brought into
focus (Step Sc6). Furthermore, the body microcomputer 50 obtains
information regarding whether the object is in front focus or back
focus and the Df amount, and then, obtains defocus information
(Step Sc7). Thereafter, the process proceeds to Step Sc10.
[0222] In parallel with Steps Sc6 and Sc7, photometry is performed
(Step Sc8), and also image blur detection is started (Step Sc9).
Steps Sc6 and Sc7 are the same as Steps Sa9 and Sa10 in phase
difference detection AF. Thereafter, the process proceeds to Step
Sc10. Note that, after Step Sc9, the process may also proceed to
Step Sa11, instead of Sc10.
[0223] As decried above, in this embodiment, using light which has
entered the imaging device 10 and has been transmitted through the
imaging device 10, the above-described focus detection based on a
phase difference is performed. Thus, in parallel with the
above-described focus detection, photometry can be performed using
the imaging device 10.
[0224] In Step Sc10, the body microcomputer 50 drives the focus
lens group 72 based on the defocus information obtained in Step
Sc7.
[0225] The body microcomputer 50 determines whether or not a
contrast peak has been detected (Step Sc11). If the contrast peak
has no't been detected (NO), driving of the focus lens group 72
(Step Sc10) is repeated. If the contrast peak has been detected
(YES), driving of the focus lens group 72 is halted, and the focus
lens group 72 is moved to a position where the contrast value has
reached the peak. Then, the process proceeds to Step Sa11.
[0226] Specifically, in Steps Sc10 and Sc11, it is preferable that,
based on the defocus direction and the defocus amount calculated in
Step Sc7, the focus lens group 72 is moved at high speed, and then,
the focus lens group 72 is moved at lower speed than the high speed
to detect the contrast peak.
[0227] In this case, it is preferable that an moving amount of the
focus lens group 72 which is moved based on the calculated defocus
amount (i.e., a position to which the focus lens group 72 is to be
moved) is set to be different from that in Step Sa7 in phase
difference detection AF. Specifically, in Step Sa7 in phase
difference detection AF, the focus lens group 72 is moved to a
position which is estimated as a focus position, based on the
defocus amount. In contrast, in Step Sc10 in hybrid AF, the focus
lens group 72 is driven to a position shifted forward or backward
from the position estimated as a focus position based on the
defocus amount. Thereafter, in hybrid AF, the contrast peak is
detected while the focus lens group 72 is driven toward the
position estimated as the focus position.
[0228] In Step Sa11, the body microcomputer 50 remains in a standby
state until the release button 40b is pressed all the way down by
the user. A flow of steps after the release button 40b is pressed
all the way down is the same as that of phase difference detection
AF.
[0229] As has been described, in hybrid AF, first, defocus
information is obtained by the phase difference detection unit 20,
and the focus lens group 72 is driven based on the defocus
information. Then, the position of the focus lens group 72 at which
the contrast value calculated based on an output from the imaging
device 10 reaches its peak is detected, and the focus lens group 72
is moved to the position. Thus, defocus information can be detected
before driving the focus lens group 72, and therefore, as opposed
to contrast detection AF, the step of tentatively driving the focus
lens group 72 is not necessary. This allows reduction in processing
time for autofocusing. Moreover, an object image is brought into
focus by contrast detection AF eventually, and therefore,
particularly, an object having a repetitive pattern, an object
having extremely low contrast, and the like can be brought into
focus with higher accuracy than in phase difference detection
AF.
[0230] Since defocus information is obtained by the phase
difference detection unit 20 using light transmitted through the
imaging device 10, photometry by the imaging device 10 can be
performed in parallel with obtaining defocus information by the
phase difference detection unit 20, although hybrid AF includes
phase difference detection. As a result, a mirror for dividing a
part of light from an object does not have to be provided for phase
difference detection, and also, a photometry sensor does not have
to be additionally provided. Furthermore, photometry can be
performed before the release button 40b is pressed all the way
down, so that a release time lag can be reduced. In the
configuration in which photometry is performed before the release
button 40b is pressed all the way down, photometry can be performed
in parallel with obtaining defocus information, thereby preventing
increase in processing time after the release button 40b is pressed
halfway down.
[0231] --Variations--
[0232] In the above description, after the release button 40b is
pressed all the way down, stopping down is performed immediately
before exposure. In the following description, a variation
configured so that, in phase difference detection AF and hybrid AF,
before the release button 40b is pressed all the way down, stopping
down is performed before autofocusing will be described.
[0233] (Phase Difference Detection AF)
[0234] Specifically, first, the shooting operation of the camera
system in phase difference detection AF according to the variation
will be described with reference to FIG. 15.
[0235] Steps (Steps Sd1-Sd5) from the step in which the power
switch 40a is turned on to the step in which the body microcomputer
remains in a standby state until the release button 40b is pressed
halfway down are the same as Steps Sa1-Sa5 in phase difference
detection AF which have been described above.
[0236] When the release button 40b is pressed half way down by a
user (Step Sd5), image blur detection is started (Step Sd6), and in
parallel with Step Sd6, photometry is performed (Step Sd7). Steps
Sd5 and Sd6 are the same as Steps Sa9 and Sa10 in phase difference
detection AF.
[0237] Thereafter, an aperture value at the time of exposure is
obtained based on a result of photometry in Step Sd7, and whether
or not the obtained aperture value is larger than a predetermined
aperture threshold value is determined (Step Sd8). Then, when the
obtained aperture value is larger than the predetermined aperture
threshold value (YES), the process proceeds to Step Sd10. When the
obtained value is equal to or smaller than the predetermined
aperture threshold value (NO), the process proceeds to Step Sd9. In
Step Sd9, the body microcomputer 50 drives the aperture section 73
via the lens microcomputer 80 to attain the obtained aperture
value.
[0238] In this case, the predetermined aperture threshold value is
set to be about an aperture value at which defocus information can
be obtained based on an output of the line sensor 24a of the phase
difference detection unit 20. That is, assuming that the aperture
value obtained based on the result of photometry is larger than the
aperture threshold value, if the aperture section 73 is stopped
down to the aperture value, defocus information cannot be obtained
by the phase difference detection unit 20. Therefore, the aperture
section 73 is not stopped down, and the process proceeds to Step
Sd10. On the other hand, when the aperture value obtained based on
the result of photometry is equal to or smaller than the aperture
threshold value, the aperture section 73 is stopped down to the
aperture value, and then, the process proceeds to Step Sd10.
[0239] In Steps Sd10-Sd12, similarly to Steps Sa6-Sa8 in phase
difference detection AF described above, the body microcomputer 50
obtains defocus information based on an output from the line sensor
24a of the phase difference detection unit 20 (Step Sd10), drives
the focus lens group 72 based on the defocus information (Step
Sd11), and determines whether or not an object image has been
brought into focus (Step Sd12). After an object image has been
brought into focus, the process proceeds to Step Sa11.
[0240] In Step Sa11, the body microcomputer remains in a standby
state until the release button 40b is pressed all the way down by
the user. A flow of steps after the release button 40b is pressed
all the way down is the same as that of phase difference detection
AF described above.
[0241] It should be noted that only when it is determined in Step
Sd8 that the aperture value obtained based on the result of
photometry is larger than the predetermined aperture threshold
value, stopping down of the aperture section 73 is performed in
Step Sa14. That is, when it is determined in Step Sd8 that the
aperture value obtained based on the result of photometry is equal
to or smaller than the predetermined aperture threshold value, Step
Sa14 does not have to be performed because stopping down of the
aperture section 73 is performed beforehand in Step Sd9.
[0242] As described above, in the shooting operation of the camera
system in phase difference detection AF according to the variation,
when the aperture value at the time of exposure obtained based on
the result of photometry is about a value at which phase difference
detection AF can be performed, the aperture section 73 is stopped
down in advance of exposure before autofocusing. Thus, stopping
down of the aperture section 73 does not have to be performed after
the release button 40b is pressed all the way down, so that a
release time lag can be reduced.
[0243] (Hybrid AF)
[0244] Next, the shooting operation of the camera system in hybrid
AF according to the variation will be described with reference to
FIG. 16.
[0245] Steps (Steps Se1-Se5) from the step in which the power
switch 40a is turned on to the step in which the body microcomputer
remains in a standby state until the release button 40b is pressed
halfway down are the same as Steps Sa1-Sa5 in phase difference
detection AF which have been described above.
[0246] When the release button 40b is pressed half way down by a
user (Step Se5), image blur detection is started (Step Se6), and in
parallel with Step Se6, photometry is performed (Step Se7). Steps
Se6 and Se7 are the same as Steps Sa9 and Sa10 in phase difference
detection AF.
[0247] Thereafter, an aperture value at the time of exposure is
obtained based on a result of photometry in Step Se7, and whether
or not the obtained aperture value is larger than a predetermined
aperture threshold value is determined (Step Se8). Then, when the
obtained aperture value is larger than the predetermined aperture
threshold value (YES), the process proceeds to Step Se10. When the
obtained value is equal to or smaller than the predetermined
aperture threshold value (NO), the process proceeds to Step Se9. In
Step Se9, the body microcomputer 50 drives the aperture section 73
via the lens microcomputer 80 to attain the obtained aperture
value.
[0248] In this case, the predetermined aperture threshold value is
set to be about an aperture value at which a peak of a contrast
value calculated from an output of the imaging device 10 can be
detected. That is, assuming that the aperture value obtained based
on the result of photometry is larger than the aperture threshold
value, if the aperture section 73 is stopped down to the aperture
value, contrast peak detection, which will be described later,
cannot be performed. Therefore, the aperture section 73 is not
stopped down, and the process proceeds to Step Se10. On the other
hand, when the aperture value obtained based on the result of
photometry is equal to or smaller than the aperture threshold
value, the aperture section 73 is stopped down to the aperture
value, and then, the process proceeds to Step Se10.
[0249] In Steps Se10-Se12, similarly to Steps Sc6, Sc7, Sc10 and
Sc11 in normal hybrid AF described above, the body microcomputer 50
defocus information based on an output from the line sensor 24a of
the phase difference detection unit 20 (Steps Se10 and Se11),
drives the focus lens group 72 based on the defocus information
(Step Se12), and detects the contrast peak to move the focus lens
group 72 to a position where the contrast value has reached the
peak (Step Se13).
[0250] Thereafter, in Step Sa11, the body microcomputer remains in
a standby state until the release button 40b is pressed all the way
down by the user. A flow of steps after the release button 40b is
pressed all the way down is the same as that of normal phase
difference detection AF described above.
[0251] It should be noted that only when it is determined in Step
Se8 that the aperture value obtained based on the result of
photometry is larger than the predetermined aperture threshold
value, stopping down of the aperture section 73 is performed in
Step Sa14. That is, when it is determined in Step Se8 that the
aperture value obtained based on the result of photometry is equal
to or smaller than the predetermined aperture threshold value, Step
Sa14 does not have to be performed because stopping down of the
aperture section 73 is performed beforehand in Step Se9.
[0252] As described above, in the shooting operation of the camera
system in hybrid AF according to the variation, when the aperture
value at the time of exposure obtained based on the result of
photometry is about a value at which contrast detection AF can be
performed, the aperture section 73 is stopped down in advance of
exposure before autofocusing. Thus, stopping down of the aperture
section 73 does not have to be performed after the release button
40b is pressed all the way down, and therefore, a release time lag
can be reduced.
[0253] --Continuous Shooting Mode--
[0254] In the above description, each time the release button 40b
is pressed all the way down, a single image is shot. The camera 100
has a continuous shooting mode in which a plurality of images are
shot by pressing the release button 40b all the way down once.
[0255] The continuous shooting mode will be described hereinafter
with reference to FIGS. 17 and 18. In the following description, it
is assumed that hybrid AF according to the variation is performed.
Note that the continuous shooting mode is not limited to hybrid AF
according to the variation, but can be employed in any
configuration using phase difference detection AF, contrast
detection AF, hybrid AF, phase difference detection AF according to
the variation, or the like.
[0256] Steps (Steps Sf1-Sf13) from the step in which the power
switch 40a is turned on to the step in which a release button 40b
is pressed halfway down and the focus lens group 72 is moved to the
position where the contrast value has reached the peak are the same
as Steps Se1-Se13 in hybrid AF according to the variation.
[0257] After the focus lens group 72 is moved to the position where
the contrast value has reached the peak, the body microcomputer 50
causes the memory section to store a distance between two object
images formed on the line sensor 24a at that time (i.e., when an
object image has been brought into focus using contrast detection
AF) (Step Sf14).
[0258] Thereafter, in Step Sf15, the body microcomputer remains in
a standby state until the release button 40b is pressed all the way
down by the user. When the release button 40b is pressed all the
way down by the user, exposure is performed in the same manner as
in Steps Sa12-Sa17 in phase difference detection AF.
[0259] Specifically, the body microcomputer 50 temporarily puts the
shutter unit 42 into a close state (Step Sf16), image blur
correction is started (Step Sf17), and if the aperture section 73
is not stopped down in Step Sf9, the aperture section 73 is stopped
down based on a result of photometry (Step Sf18). Thereafter, the
shutter unit 42 is put into an open state (Step Sf19), exposure is
started (Step Sf20), and the shutter unit 42 is put into a close
state (Step Sf21) to terminate the exposure.
[0260] After the exposure is terminated, whether or not the release
button 40b has been released from being pressed all the way down is
determined (Step Sf22). When the release button 40b has been
released (YES), the process proceeds to Steps Sf29 and Sf30. On the
other hand, when the release button 40b is continuously pressed all
the way down (NO), the process proceeds to Step Sf23 to perform
continuous shooting.
[0261] When the release button 40b is continuously pressed all the
way down, the body microcomputer 50 puts the shutter unit 42 into
an open state (Step Sf23), and phase difference detection AF is
performed (Steps Sf24-Sf26).
[0262] Specifically, an in-focus state of an object image in the
imaging device 10 is detected via the phase difference detection
unit 20 (Step Sf24), defocus information is obtained (Step Sf25),
and the focus lens group 72 is driven based on the defocus
information (Step Sf26).
[0263] In this case, in hybrid AF before the release button 40b is
pressed all the way down, a distance between two object images
formed on the line sensor 24a is compared to a reference distance
which has been set beforehand to obtain the defocus information
(Step Sf11). In contrast, in Steps Sf24 and Sf25 after the release
button 40b is pressed all the way down, the distance between two
object images formed on the line sensor 24a is compared to the
distance of two object images formed on the line sensor 24a which
has been stored in Step Sf14 after contrast detection AF in hybrid
AF to obtain an in-focus state and defocus information.
[0264] After phase difference detection AF is performed in the
above-described manner, the body microcomputer 50 determines
whether or not it is a timing of outputting a signal (i.e., an
exposure start signal) for starting exposure from the body
microcomputer 50 to the shutter control section 51 and the imaging
unit control section 52 (Step Sf27). This output timing of the
exposure start signal is a timing of performing continuous shooting
in continuous shooing mode. When it is not the output timing of the
exposure start signal (NO), phase distance detection AF is repeated
(Steps Sf24-Sf26). On the other hand, when it is the output timing
of the exposure start signal (YES), driving of the focus lens group
72 is halted (Step Sf28) to perform exposure (Step Sf20).
[0265] Note that after the focus lens group 72 is halted, it is
necessary to sweep out, before starting exposure, electrical
charges accumulated in the light receiving sections 11b of the
imaging device 10 during phase difference detection AF. Therefore,
electrical charges in the light receiving sections 11b are swept
out using an electronic shutter, or the shutter unit 42 is
temporarily put into a close state to sweep out electrical charges
in the light receiving sections 11b, and then the shutter unit 42
is put into an open state to start exposure.
[0266] After the exposure is terminated, whether or not the release
button 40b has been released from being pressed all the way down is
determined again (Step Sf22). As long as the release button 40b is
pressed all the way down, phase difference detection AF and
exposure are repeated (Steps Sf23-Sf28 and Steps Sf20 and
Sf21).
[0267] When the release button 40b has been released from being
pressed all the way down, image blur correction is terminated (Step
Sf29), and also, the aperture section 73 is opened up (Step Sf30)
to put the shutter unit 42 into an open state (Step Sf31).
[0268] After completing resetting, when a shooting sequence is
terminated, the process returns to Step Say, and the body
microcomputer remains in a standby state until the release button
40b is pressed halfway down.
[0269] When the power switch 40a is turned off (Step Sf32), the
body microcomputer 50 moves the focus lens group 72 to a
predetermined reference position which has been set beforehand
(Step Sf33), and puts the shutter unit 42 into a close state (Step
Sf34). Then, respective operations of the body microcomputer 50 and
other units in the camera body 4, and the lens microcomputer 80 and
other units in the interchangeable lens 7 are halted.
[0270] As described above, in the shooting operation of the camera
system in the continuous shooting mode, phase difference detection
AF can be performed between exposures during continuous shooting,
so that a high focus performance can be realized.
[0271] Also, since autofocusing is performed using phase difference
detection AF in this case, the defocus direction can be instantly
obtained, and thus, an object can be instantly brought into focus
even in a short time between shootings continuously performed.
[0272] Furthermore, as opposed to a known technique, even in phase
difference detection AF, a movable mirror for phase difference
detection does not have to be provided. Thus, a release time lag
can be reduced, and also, power consumption can be reduced.
Moreover, according to the known technique, a release time lag
corresponding to the vertical movement of the movable mirror is
generated, and thus, when an object is a moving object, it is
necessary to predict the movement of the moving object during the
release time lag and then shoot an image. However, according to
this embodiment, there is no release time lag corresponding to the
vertical movement of the movable mirror, and therefore, focus can
be achieved while following the movement of an object until
immediately before exposure.
[0273] In phase difference detection AF during continuous shooting,
as the reference distance between two object images formed on the
line sensor 24a based on which whether or not an object image has
been brought into focus is determined, the distance between two
object images formed on the line sensor 24a when the release button
40b is pressed halfway down and an object image has been brought
into focus by contrast detection AF is used. Thus, highly accurate
autofocusing which corresponds to actual equipment and actual
shooting conditions can be performed.
[0274] At the time of shooting for the first frame in the
continuous shooting mode, the autofocusing method is not limited to
hybrid AF. Phase difference detection AF or contrast detection AF
may be used. However, as described above, if AF such as hybrid AF
and contrast detection AF in which focus adjustment is eventually
performed based on the contrast value is employed at the time of
shooting for the first frame, phase difference detection AF at the
time of shooting for second and subsequent frames can be performed
based on a highly accurate in-focus state obtained at the time of
shooting for the first frame. Note that when phase difference
detection AF is used, Step Sf14 is not performed, the distance
between two object images formed on the line sensor 24a is compared
to the reference distance which has been set beforehand to obtain
an in-focus state and defocus information.
[0275] Not only in the continuous shooting mode but also in normal
shooting, the camera system may be configured so that when an
object is a moving object, phase difference detection AF is
performed until the release button 40b is pressed all the way down
even after an object image has been brought into focus.
[0276] --Low Contrast Mode--
[0277] The camera 100 of this embodiment is configured so that the
autofocusing method is switched according to the contrast of an
object. That is, the camera 100 has a low contrast mode in which
shooting is performed under a low contrast condition.
[0278] The low contrast mode will be described hereinafter with
reference to FIG. 19. In the following description, it is assumed
that hybrid AF is performed. Note that the low contrast mode is not
limited to hybrid AF, but can be employed in any configuration
using phase difference detection AF, contrast detection AF, phase
difference detection AF according to the variation, hybrid AF
according to the variation, or the like.
[0279] Steps (Steps Sg1-Sg5) from the step in which the power
switch 40a is turned on to the step in which the body microcomputer
remains in a standby state until the release button 40b is pressed
halfway down are the same as Steps Sa1-Sa5 in phase difference
detection AF.
[0280] When the release button 40b is pressed halfway down by a
user (Step Sg5), the body microcomputer 50 amplifies an output from
the line sensor 24a of the phase difference detection unit 20, and
then performs an operation by the arithmetic circuit (Step Sg6).
Then, whether or not a low contrast state has occurred is
determined (Step Sg7). Specifically, it is determined whether or
not a contrast value is high enough to detect respective positions
of two object images formed on the line sensor 24a based on the
output from the line sensor 24a.
[0281] When the contrast value is high enough to detect the
positions of the two object images (NO), it is determined that a
low contrast state has not occurred, and the process proceeds to
Step Sg8 to perform hybrid AF. Note that Steps Sg8-Sg10 are the
same as Steps Sc7, Sc10 and Sc11 in hybrid AF.
[0282] On the other hand, when the contrast value is not high
enough to detect the position of the two object images (YES), it is
determined that a low contrast state has occurred, and the process
proceeds to Step Sg11 to perform contrast detection AF. Note that
Steps Sg11-Sg15 are the same as Steps Sb6-Sb10 in contrast
detection AF.
[0283] After hybrid AF or contrast detection AF is preformed in the
above-described manner, the process proceeds to Step Sa11.
[0284] In parallel with this autofocus operation (Steps Sg6-Sg15),
photometry is performed (Step Sg16), and image blur detection is
started (Step Sg17). Steps Sg16 and Sg17 are the same as Steps Sa9
and Sa11) in phase difference detection AF. Thereafter, the process
proceeds to Step Sa11.
[0285] In Step Sa11, the body microcomputer remains in a standby
state until the release button 40b is pressed all the way down by
the user. A flow of steps after the release button 40b is pressed
all the way down is the same as that of normal hybrid detection
AF.
[0286] That is, in the low contrast mode, when the contrast at the
time of shooting is high enough to perform phase difference
detection AF, hybrid AF is performed. On the other hand, when the
contrast at the time of shooting is so low that phase difference
detection AF cannot be performed, contrast detection AF is
performed.
[0287] In this embodiment, first, it is determined whether or not
an in-focus state can be detected using phase difference detection
based on the output of the line sensor 24a of the phase difference
detection unit 20, and then, hybrid AF or contrast detection AF is
selected. However, the present invention is not limited thereto.
For example, the camera system may be configured so that after the
release button 40b is pressed halfway down, the contrast value is
obtained from an output of the imaging device 10 to determine
whether or not the contrast value obtained from the output of the
imaging device 10 is higher than a predetermined value before a
phase difference focus is detected (i.e., between Steps Sg5 and Sg6
in FIG. 19). The predetermined value is set to be about a contrast
value at which a position of an object image formed on the line
sensor 24a can be detected. That is, the camera system may be
configured so that, when the contrast value obtained from the
output of the imaging device 10 is approximately equal to or larger
than a value at which an in-focus state can be detected using phase
difference detection, hybrid AF is performed and, on the other
hand, when the contrast value obtained from the output of the
imaging device 10 is smaller than the value at which an in-focus
state can be detected using phase difference detection, contrast
detection AF is performed.
[0288] Also, in this embodiment, when an in-focus state can be
detected using phase difference detection, hybrid AF is performed.
However, the camera system may be configured so that, when an
in-focus state can be detected using phase difference detection,
phase difference detection AF is performed.
[0289] As described above, in the camera 100 including the imaging
unit 1 for receiving light transmitting through the imaging device
10 by the phase difference detection unit 20, the movable mirror of
the known technique for guiding light to the phase difference
detection unit is not provided, but phase difference detection AF
(including hybrid AF) and contrast detection AF can be performed.
Thus, a highly accurate focus performance can be realized by
selecting one of phase difference detection AF and contrast
detection AF according to the contrast.
[0290] --AF Switching According to Interchangeable Lens--
[0291] Furthermore, the camera 100 of this embodiment is configured
so that the autofocusing method is switched according to the type
of the interchangeable lens 7 attached to the camera body 4.
[0292] An AF switching function according to the type of the
interchangeable lens will be described hereinafter with reference
to FIG. 20. In the following description, it is assumed that hybrid
AF is performed. Note that the AF switching function according to
the interchangeable lens is not limited to hybrid AF, but can be
employed in any configuration using phase difference detection AF,
contrast detection AF, phase difference detection AF according to
the variation, hybrid AF according to the variation, or the
like.
[0293] Steps (Steps Sh1-Sh5) from the step in which the power
switch 40a is turned on to the step in which the body microcomputer
remains in a standby state until the release button 40b is pressed
halfway down are the same as Steps Sa1-Sa5 in phase difference
detection AF.
[0294] When the release button 40b is pressed half way down by a
user (Step Sh5), photometry is performed (Step Sh6), and in
parallel with Step Sh6, image blur detection is started (Step Sh7).
Steps Sh6 and Sh7 are the same as Steps Sa9 and Sa10 in phase
difference detection AF. Note that the photometry and image blur
detection may be performed in parallel with an autofocus operation,
which will be described later.
[0295] Thereafter, the body microcomputer 50 determines whether or
not the interchangeable lens 7 is a reflecting telephoto lens
produced by a third party or a smooth trans focus (STF) lens based
on information from the lens microcomputer 80 (Step Sh8). When the
interchangeable lens 7 is a reflecting telephoto lens produced by a
third party or a STF lens (YES), the process proceeds to Step Sh13
to perform contrast detection AF. Note that Steps Sh13-Sh17 are the
same as Steps Sb6-Sb10 in contrast detection AF.
[0296] On the other hand, when the interchangeable lens 7 is not
either a reflecting telephoto lens produced by a third party or a
STF lens (NO), the process proceeds to Step Sh9 to perform hybrid
AF. Note that Steps Sh9-Sh12 are the same as Steps Sc6, Sc7, Sc10
and Sc11 in hybrid AF.
[0297] After contrast detection AF or hybrid AF is performed in the
above-described manner, the process proceeds to Step Sa11.
[0298] In Step Sa11, the body microcomputer remains in a standby
state until the release button 40b is pressed all the way down by
the user. A flow of steps after the release button 40b is pressed
all the way down is the same as that of hybrid AF.
[0299] That is, when the interchangeable lens 7 is a reflecting
telephoto lens produced by a third party or a STF lens, phase
difference detection might not be performed with high accuracy, and
therefore, hybrid AF (specifically, phase difference detection AF)
is not performed, but contrast detection AF is performed. On the
other hand, when the interchangeable lens 7 is not either a
reflecting telephoto lens produced by a third party or a STF lens,
hybrid AF is performed. That is, the body microcomputer 50
determines whether or not it is ensured that an optical axis of the
interchangeable lens 7 properly extends so that phase difference
detection AF can be performed. Then, only when it is ensured that
the optical axis of the interchangeable lens 7 properly extends so
that phase difference detection AF can be performed, hybrid AF is
performed. If it is not ensured that the optical axis of the
interchangeable lens 7 properly extends so that phase difference
detection AF can be performed, contrast detection AF is
performed.
[0300] As described above, in the camera 100 including the imaging
unit 1 for receiving light transmitting through the imaging device
10 by the phase difference detection unit 20, the movable mirror of
the known technique for guiding light to the phase difference
detection unit is not provided, but phase difference detection AF
(including hybrid AF) and contrast detection AF can be performed.
Thus, a highly accurate focus performance can be realized by
selecting one of phase difference detection AF and contrast
detection AF according to the type of the interchangeable lens
7.
[0301] According to this embodiment, it is determined which of
hybrid AF and contrast detection AF is to be performed depending on
whether or not the interchangeable lens 7 is a reflecting telephoto
lens produced by a third party or a STF lens. However, the present
invention is not limited thereto. The camera system may be
configured to determine which of hybrid AF and contrast detection
AF is to be performed depending on only whether or not the
interchangeable lens 7 is produced by a third party, regardless of
whether or not the interchangeable lens 7 is a reflecting telephoto
lens or a STF lens.
[0302] Also, according to this embodiment, the camera system is
configured so that when the interchangeable lens 7 is not either a
reflecting telephoto lens produced by a third party or a STF lens,
hybrid AF is performed. However, the camera system may be
configured so that when the interchangeable lens 7 is not either a
reflecting telephoto lens produced by a third party or a STF lens,
phase difference detection AF is performed.
[0303] Therefore, according to this embodiment, the imaging device
10 is configured so that light passes through the imaging device
10, and the phase difference detection unit 20 for receiving light
which has passed through the imaging device 10 to perform phase
difference detection is provided. Moreover, the body control
section 5 controls the imaging device 10 and also controls driving
of the focus lens group 72 at least based on a detection result of
the phase difference detection unit 20 to perform focus adjustment.
Thus, various types of processing using the imaging device 10 can
be performed in parallel with autofocusing (phase difference
detection AF and hybrid AF which have been described above) using
the phase difference detection unit 20, so that the processing time
can be reduced.
[0304] Also, in the above-described configuration, when light
enters the imaging device 10, light also enters the phase
difference detection unit 20. Thus, even if various types of
processing using the imaging device 10 are not performed in
parallel with autofocusing the phase difference detection unit 20,
switching between various types of processing using the imaging
device 10 and autofocusing the phase difference detection unit 20
can be performed in a simple manner by changing a control mode of
the body control section 5. That is, compared to a known
configuration in which the direction in which light travels from an
object is switched between the direction toward an imaging device
and the direction toward a phase difference detection unit by
moving a movable mirror forward/backward, the movable mirror does
not have to be moved forward/backward, so that switching between
various types of processing using the imaging device 10 and
autofocusing the phase difference detection unit 20 can be quickly
performed. Also, noise is not caused by moving the movable mirror
forward/backward, and thus, switching between various types of
processing using the imaging device 10 and autofocusing the phase
difference detection unit 20 can be quietly performed.
[0305] Thus, the convenience of the camera 100 can be improved.
[0306] Specifically, the imaging device 10 is configured so that
light passes through the imaging device 10, and the phase
difference detection unit 20 for receiving light which has passed
through the imaging device 10 to perform phase difference detection
is provided, so that AF using the phase difference detection unit
20, such as the above-described phase difference detection AF, and
photometry using the imaging device 10 can be performed in
parallel. Thus, photometry does not have to be performed after
pressing the release button 40b all the way down, thus resulting in
reduction in a release time lag. Even in the configuration in which
photometry is performed before the release button 40b is pressed
all the way down, increase in processing time after the release
button 40b is pressed halfway down can be prevented by performing
photometry in parallel with autofocusing. Furthermore, since
photometry is performed using the imaging device 10, there is no
need to additionally provide a photometry sensor. Also, a movable
mirror for guiding light from an object to the photometry sensor or
the phase difference detection unit does not have to be provided.
Therefore, power consumption can be reduced.
[0307] Also, the imaging device 10 is configured so that light
passes through the imaging device 10, and the phase difference
detection unit 20 for receiving light which has passed through the
imaging device 10 to perform phase difference detection is
provided, so that the driving direction of the focus lens group 72
is determined based on a detection result of the phase difference
detection unit 20, and then, contrast detection AF based on an
output of the imaging device 10 can be quickly performed as in the
above-described hybrid AF. That is, switching from phase difference
detection by the phase difference detection unit 20 to contrast
detection using the imaging device 10 can be quickly performed by
control of the body control section 5 without performing switching
the optical path using a movable mirror, or the like, in a known
manner, thereby reducing a time required for hybrid AF. A movable
mirror is not needed, and therefore, noise caused by such a movable
mirror is not generated and hybrid AF can be performed quietly.
[0308] Furthermore, the body control section 5 performs photometry
using the imaging device 10 and controls the aperture section 73
based on the result of the photometry to adjust the amount of
light, and then, phase difference detection is performed by the
phase difference detection unit 20. Thus, stopping down does not
have to be performed after the release button 40b is pressed all
the way down, thus reducing a release time lag. Then, the imaging
device 10 is configured so that light passes through the imaging
device 10, and the phase difference detection unit 20 for receiving
light which has passed through the imaging device 10 to perform
phase difference detection is provided, so that when photometry
using the imaging device 10 and phase difference detection using
the phase difference detection unit 20 are performed in succession,
switching between photometry by the imaging device 10 and phase
difference detection by the phase difference detection unit 20 can
be performed quickly and quietly by control of the body control
section 5.
[0309] In the continuous shooting mode, the body control section 5
performs, based on the detection result of the phase difference
detection unit 20, phase difference detection AF at the time of
shooting for second and subsequent frames. Thus, phase difference
detection AF can be performed between frames during continuous
shooting, so that the focusing performance can be improved. Then,
the imaging device 10 is configured so that light passes through
the imaging device 10, and the phase difference detection unit 20
for receiving light which has passed through the imaging device 10
to perform phase difference detection is provided, so that
switching between exposure by the imaging device 10 and AF by the
phase difference detection unit 20 can be quickly and quietly
performed. Thus, phase difference detection AF between frames
during continuous shooting can be realized.
[0310] Also, since autofocusing is performed using phase difference
detection AF in this case, the defocus direction can be instantly
obtained, and thus, an object can be instantly brought into focus
even in a short time between shootings continuously performed.
[0311] In shooting for the second and subsequent frames, phase
difference detection AF is continuously performed until a next
shooting timing, and thus, even if an object moves between
shootings continuously performed, it is possible to follow the
movement of the object and to bring the object in focus.
[0312] Furthermore, since there is no release time lag
corresponding to the movement of a movable mirror in the
forward/backward directions, it is possible to follow the movement
of the object to bring an object in focus until immediately before
exposure. Thus, even if an object is a moving object, the object
can be brought into focus with high accuracy without performing
moving object prediction.
[0313] At the time of shooting for a first frame in the continuous
shooting mode, AF (i.e., contrast detection AF or hybrid AF) for
eventually adjusting a focus based on a contrast value is
performed. After an object image has been brought into focus, phase
difference detection is performed by the phase difference detection
unit 20, and a result of the detection is stored. At the time of
shooting for second and subsequent frames, phase difference
detection AF is performed based on the detection result of the
phase difference detection unit 20 after the focusing for the first
frame. Thus, highly accurate autofocusing which corresponds to
actual equipment and actual shooting conditions can be
performed.
[0314] In the low contrast mode, the body control section 5
performs focus adjustment at least based on the detection result of
the phase difference detection unit 20 when the contrast value of
an object is a predetermined value or larger, and performs focus
adjustment not using the detection result of the phase difference
detection unit 20 but based on an output of the imaging device 10
when the contrast value of the object is smaller than the
predetermined value. Thus, the object can be brought into focus
with high accuracy using AF using a suitable autofocusing method
according to the contrast of the object. Specifically, the body
control section 5 performs AF (i.e., phase difference detection AF
or hybrid AF) using the phase difference detection unit 20 when the
contrast value of the object is large enough to perform phase
difference detection AF, and performs contrast detection AF when
the contrast value of the object is so low that phase difference
detection AF cannot be performed. Thus, the object can be brought
into focus by AF using a suitable method which corresponds to the
contrast of the object, so that the object can be brought into
focus with high accuracy.
[0315] The body control section 5 switches an AF method between AF
at least based on a detection result of the phase difference
detection unit 20 and AF based on an output of the imaging device
10 without using the detection result of the phase difference
detection unit 20 according to the type of the interchangeable lens
7. Thus, focus can be achieved by AF using a suitable method which
corresponds to the interchangeable lens 7. Specifically, the body
control section 5 performs contrast detection AF when the
interchangeable lens 7 is a reflecting telephoto lens produced by a
third party (i.e., produced by a different manufacturer from a
manufacturer of the camera body 4), or a STF lens, and performs AF
(i.e., phase difference detection AF of hybrid AF) at least using
the phase difference detection unit 20 when the interchangeable
lens 7 is not a product by a third party or a reflecting telephoto
lens, and also not a STF lens. In other words, only when the
interchangeable lens 7 ensured that an optical axis is so proper
that phase difference detection AF can be performed is attached to
the camera body 4, hybrid AF is performed. If it is not ensured
that the optical axis of the interchangeable lens 7 is so proper
that phase difference detection AF can be performed, contrast
detection AF is performed. Thus, the object image can be brought
into focus by AF using a suitable method which corresponds to the
interchangeable lens 7, so that focus can be achieved with high
accuracy.
[0316] In the known configuration in which light directed from an
object to the imaging device 10 is guided to a phase difference
detection unit provided at some other position than the back
surface side of the imaging device 10 using a movable mirror or the
like, accuracy in focus adjustment is not high because of a
difference between the optical path at the time of exposure and the
optical path at the time of phase difference detection, an
arrangement error, and the like. In contrast, in this embodiment,
the phase difference detection unit 20 receives light passing
through the imaging device 10 to perform phase difference
detection, and thus, phase difference detection can be performed
using the same optical path as that at the time of exposure. Also,
a member such as a movable mirror which causes an error is not
provided. Thus, the accuracy of focus adjustment based on phase
difference detection can be improved.
[0317] --During-Exposure AF Shooting Mode--
[0318] In the above-described normal shooting mode, driving of the
focus lens group 72 is halted during exposure. However, the camera
100 has a during-exposure AF shooting mode in which autofocusing is
also performed during exposure.
[0319] Specifically, the camera 100 is configured so that switching
between the during-exposure AF shooting mode in which exposure is
performed while performing AF and the normal shooting mode in which
the focus lens group 72 is halted at the time of exposure can be
performed by turning on/off the during-exposure AF setting switch
40e by a user.
[0320] The shooting mode is switched to the during-exposure AF
shooting mode by turning on the during-exposure AF setting switch
40e, but is also automatically switched to the during-exposure AF
shooting mode according to an object point distance (i.e., a
distance from a lens to an object). That is, the camera body 4 is
configured to be capable of calculating the object point distance
and to perform, when the object point distance is smaller than a
predetermined distance, during-exposure AF shooting even with the
during-exposure AF setting switch being turned off. Specifically,
the body microcomputer 50 calculates the object point distance
based on a detection result from the absolute position detection
section 81a and lens information of the interchangeable lens 7 and
sets, when the calculated object point distance is a predetermined
threshold or smaller, the shooting mode to be the during-exposure
AF shooting mode. On the other hand, when the calculated object
point distance is larger than the predetermined threshold, the body
microcomputer 50 sets the shooting mode to be the normal shooting
mode. That is, the body control section 5 and the absolute position
detection section 81a serve as a distance detection section. Note
that although the body control section 5 has both of the functions
as the distance detection section for detecting a distance to an
object and the control section for controlling the imaging device
10, a separate distance detection section for detecting a distance
to the object may be additionally provided.
[0321] As described above, the camera 100 is configured so that the
shooting mode is switched between the during-exposure AF shooting
mode and the normal shooting mode according to an operation by the
user and also the shooting mode is automatically switched between
the during-exposure AF shooting mode and the normal shooting mode
according to the object point distance. Note that a method for
detecting the object point distance is not limited to the
above-described method, but any means and method can be
employed.
[0322] Furthermore, in a macro shooting mode in which shooting
(so-called close-up shooting) is performed with a setting suitable
for shooting of an object close to a camera, the shooting mode is
automatically switched to the during-exposure AF shooting mode.
That is, the camera 100 has the macro shooting mode which is
suitable for close-up shooting, and is configured so that the
shooting mode can be switched between the macro shooting mode and
the normal shooting mode by turning on/off the macro setting switch
40f by the user.
[0323] Specifically, the camera 100 is in the normal shooting mode
when the macro setting switch 40f is in an off state, and sets a
moving range of the focus lens group 72 at the time of autofocusing
to be a range which allows focusing on an object at an object point
distance of several cm to infinity. On the other hand, when the
macro setting switch 40f is in an on state, the camera 100 is in
the macro shooting mode, and sets the moving range of the focus
lens group 72 to be a range which allows focusing on an object at
an object point distance of several cm to several tens cm. Shooting
of an object at this object point distance is assumed as close-up
shooting. That is, in the macro shooting mode, the range in which
the focus lens group 72 is moved at the time of autofocusing is set
to be a limited range which is assumed to be a range of close-up
shooting, and thus, the moving distance of the focus lens group 72
can be reduced and fast-focusing can be realized. When the macro
setting switch 40f is in an on state, the shooting mode is
automatically set to be the during-exposure AF shooting mode. That
is, when an ON signal is input from the macro setting switch 40f,
the body microcomputer 50 sets the moving range of the focus lens
group 72 at the time of autofocusing to be the above-described
limited range, and the shooting mode to be the during-exposure AF
shooting mode.
[0324] The shooting operation of the camera system in the
during-exposure AF shooting mode will be described hereinafter with
reference to FIGS. 21 and 22.
[0325] In the following description, it is assumed that hybrid AF
is performed. Note that the during-exposure AF shooting mode is not
limited to hybrid AF, but may be employed in any configuration
using phase difference detection AF, contrast detection AF, phase
difference detection AF according to the variation, hybrid AF
according to the variation, or the like.
[0326] Steps (Steps Sk1-Sk11) from the step in which the power
switch 40a is turned on to the step in which the release button 40b
is pressed halfway down and then autofocusing is completed, i.e.,
the focus lens group 72 is moved to the position where the contrast
value has reached the peak are the same as Steps Sc1-Sc11 in hybrid
AF in the normal shooting mode.
[0327] Thereafter, in Step Sk12, the body microcomputer 50
determines whether or not the during-exposure AF setting switch 40e
is in an on state. When an ON signal from the during-exposure AF
setting switch 40e is input (YES), the process proceeds to Step
Sk16 to set a during-exposure AF flag to 1. When an ON signal from
the during-exposure AF setting switch 40e is not input (NO), the
process proceeds to Step Sk13.
[0328] In Step Sk13, the body microcomputer 50 determines whether
or not the shooting mode is set to be the macro shooting mode,
i.e., whether or not the macro setting switch 40f is in an on
state. When an ON signal from the macro setting switch 40f is input
(YES), the step proceeds to Step Sk16 to set the during-exposure AF
flag to 1. When an ON signal from the during-exposure AF setting
switch 40e is not input (NO), the process proceeds to Step
Sk14.
[0329] In Step Sk14, the body microcomputer 50 calculates an object
point distance from the focus lens group 72 to an object based on a
detection result from the absolute position detection section 81a
and lens information of the interchangeable lens 7 to determine
whether or not the calculated object point distance is a
predetermined threshold or smaller. When the object point distance
is the threshold or smaller (YES), the process proceeds to Step
Sk16 to set the during-exposure AF flag to 1. When the object point
distance is larger than the threshold, the process proceeds to Step
Sk15 to set the during-exposure AF flag to 0. The threshold is set
to be an object point distance with which close-up shooting is
assumed to be performed.
[0330] Note that after setting the during-exposure AF flag in Steps
Sk15 and Sk16, the process proceeds to Step Sk17.
[0331] In Step Sk17, the body microcomputer 50 remains in a standby
state until the release button 40b is pressed all the way down by
the user. When the release button 40b is pressed all the way down
by the user, whether or not the during-exposure AF flag is 1 is
determined in Step Sk18. When the during-exposure AF flag is 0
(NO), the process proceeds to Step Sk19 to perform exposure in the
same manner as exposure in the above-described hybrid AF, i.e., as
in Sa12-Sa17 in phase difference detection AF.
[0332] When the during-exposure AF flag is 1 (YES), the process
proceeds to Step Sk19 to perform exposure, and also to Step Sk25 to
perform phase difference detection AF in parallel with Step
Sk19.
[0333] Specifically, an output from the line sensor 24a of the
phase difference detection unit 20 is amplified, and then, an
operation by the arithmetic circuit obtains information regarding
whether or not an object image has been brought into focus, whether
the object is in front focus or back focus, and the Df amount (Step
Sk25). Thereafter, the focus lens group 72 is driven in the defocus
direction by the obtained Df amount via the lens microcomputer 80
(Step Sk26). Then, whether or not the shutter unit 42 is put in a
close state is determined (Step Sk27). If the shutter unit 42 is
not in a close state (NO), the process returns to Step Sk25 to
repeat phase difference detection AF. If the shutter unit 42 is in
a close state (YES), the process proceeds to Step Sk28 to terminate
phase difference detection AF. After terminating phase difference
detection AF, the process proceeds to Step Sk31. Note that in phase
difference detection AF, light from an object has to enter the
imaging unit 1, and therefore, phase difference detection AF is
temporarily halted during Steps Sk19-Sk22 in which the shutter unit
42 is in a close state.
[0334] Process in Steps Sk29-Sk34 after exposure has been
terminated is the same as process after exposure in the
above-described hybrid AF, i.e., in Steps Sa18-Sa23 in phase
difference detection AF.
[0335] That is, in the during-exposure AF shooting mode, phase
difference detection AF is executed during exposure of the imaging
device 10. The phase difference detection AF continuously performed
while exposure is performed. Herein, "during exposure" can be also
referred to as "during a period of still image shooting by the
imaging device 10", "during a period of video signal storing by the
imaging device 10", "during a period of electrical charge storing
by the imaging device 10", or the like.
[0336] The during-exposure AF shooting mode is intentionally set by
the user by operating the during-exposure AF setting switch 40e,
and also, is automatically set when the shooting mode is the macro
shooting mode or when the object point distance is very short. In
many cases, so-called close-up shooting in which the shooting mode
is the macro shooting mode or in which the object point distance is
very short is performed indoors, compared to normal shooting other
than close-up shooting. That is, close-up shooting is performed in
a dark environment in many cases, and thus, the shutter speed has
to be reduced to set an exposure time to be long. In such a
condition, the influence of the movement (hereinafter also referred
to as "camera shake") of the camera body 4 due to hand shake of the
user and the like, and the movement of an object itself
(hereinafter also referred to as "object shake") on shooting is
increased.
[0337] In general, it has been known that an image blur correction
mechanism is provided to reduce the influence of camera shake on
shooting. The image blur correction mechanism is a mechanism for
correcting an image blur in an plane perpendicular to an optical
axis, and does not correct an image blur in the direction along the
optical axis. In this embodiment, the camera 100 includes the blur
correction unit 45 for moving the imaging unit 1 in an plane
perpendicular to the optical axis X, and the blur correction lens
driving section 74a for moving the blur correction lens 74 in a
plane perpendicular to the optical axis X. The blur correction unit
45 and the blur correction lens driving section 74a correct an
image blur in a plane perpendicular to the optical axis X, but
cannot correct an image blur in the direction along the optical
axis X.
[0338] Therefore, in the during-exposure AF shooting mode of this
embodiment, autofocusing is performed during exposure. Thus, an
imaging blur in the direction along the optical axis X during
exposure is reduced. Since autofocusing during the exposure is
performed using phase difference detection AF, the defocus
direction can be instantly obtained, and thus, an object image can
be instantly brought into focus even in a short time during which
exposure is performed.
[0339] Then, as described above, the imaging device 10 is
configured so that light passes through the imaging device 10, and
the phase difference detection unit 20 is configured to receive
light which has passed through the imaging device 10 to detect a
phase difference, and thus, phase difference detection AF while
performing exposure of the imaging device 10 can be realized. Note
that in the case of AF such as contrast detection AF and the like
using a signal from the imaging device 10, AF cannot be performed
during exposure of the imaging device 10, in other words, during a
period of image signal storing by the imaging device 10 (i.e., the
electrical charge storing period in this embodiment).
[0340] When each of the during-exposure AF setting switch 40e and
the macro setting switch 40f is in an off state, whether or not to
perform close-up shooting is determined based on the object point
distance. Then, if it is determined to perform close-up shooting,
the shooting mode is set to be the during-exposure AF shooting
mode. Thus, even when the user does not realize that shooting is
being performed in a condition where the influence of hand shake on
the direction along the optical axis X is large, the camera 100
automatically determines that shooting is being performed in such a
shooting condition to correct an image blur in the direction along
the optical axis X. If close-up shooting is not to be performed,
i.e., the object point distance is long, the influence of hand
shake in the direction along the optical axis X on shooting is
small, so that autofocusing during exposure is not performed, thus
resulting in reduction in power consumption.
[0341] Note that although autofocusing performed before exposure,
i.e., before the release button 40b is pressed all the way down may
be any one of phase difference detection AF, contrast detection AF
and hybrid AF, autofocusing during exposure is phase difference
detection AF.
[0342] Also, in this embodiment, the during-exposure AF flag
determination is performed immediately after the release button 40b
is pressed all the way down, but the present invention is not
limited thereto. For example, the camera 100 may be configured so
that the during-exposure AF flag determination is performed at the
time of starting exposure and, if the shooting mode is the
during-exposure AF shooting mode, phase difference detection AF is
started simultaneously with the start of exposure.
[0343] Therefore, according to this embodiment, the imaging device
10 is configured so that light passes through the imaging device
10, and the phase difference detection unit 20 is configured to
receive light which has passed through the imaging device 10 to
perform phase difference detection, thus realizing phase difference
detection AF while performing exposure of the imaging device 10. In
this case, autofocusing is phase difference detection AF, and thus,
the defocus direction and the defocus amount can be instantly
obtained, and an object can be quickly brought into focus. As a
result, autofocusing can be performed even in a shot time during
which exposure is performed.
[0344] Also, phase difference detection AF during exposure is
continuously performed entirely during the exposure, and thus,
highly accurate autofocusing can be performed.
[0345] Furthermore, by using exposure while performing phase
difference detection AF in the macro shooting mode or in close-up
shooting used when the object point distance is small, an image
blur in the direction along the optical axis generated due to
camera shake or object shake can be reduced.
[0346] Also, with the during-exposure AF setting switch 40e
provided, the user can set the during-exposure AF shooting mode at
the user's option. Therefore, the user can flexibly use the
during-exposure AF shooting mode not only in close-up shooting but
also when the user wants to reduce image blur in the direction
along the optical axis.
Second Embodiment
[0347] Next, a camera as an imaging apparatus according to a second
embodiment will be described.
[0348] As shown in FIG. 23, a camera 200 according to the second
embodiment includes a finder optical system 6.
[0349] --Configuration of Camera Body--
[0350] A camera body 204 further includes, in addition to
components of the camera body 4 of the first embodiment, a finder
optical system 6 for viewing an object image through a finder 65,
and a semi-transparent quick return mirror 46 for guiding incident
light from the interchangeable lens 7 to the finder optical system
6.
[0351] The camera body 204 has a finder shooting mode in which
shooting is performed while a user views an object image through
the finder optical system 6, and a live view shooting mode in which
shooting is performed while a user views an object image through
the image display section 44. The camera body 204 is provided with
a finder mode setting switch 40g. The shooting mode is set to be
the finder shooting mode is set by turning on the finder mode
setting switch 40g, and to be the live view shooting mode by
turning off the finder mode setting switch 40g.
[0352] The finder optical system 6 includes a finder screen 61 on
which reflected light from the quick return mirror 46 forms an
image, a pentaprism 62 for converting an object image projected on
the finder screen 61 into an erected image, an eye lens 63 for
enlarging the projected object image for viewing, an in-finder
display section 64 for displaying various kinds of information in a
finder viewing field, and a finder 65 provided on a back surface
side of the camera body 204.
[0353] That is, the user can observe an object image formed on the
finder screen 61 through the finder 65 via the pentaprism 62 and
the eye lens 63.
[0354] A body control section 205 further includes, in addition to
components of the body control section 5 of the first embodiment, a
mirror control section 260 for controlling flip-up of the quick
return mirror 46, which will be described later, based on a control
signal from the body microcomputer 50.
[0355] The quick return mirror 46 is a semi-transparent mirror
capable of reflecting and transmitting incident light, and is
configured to be capable of pivotally moving in front of the
shutter unit 42 between a reflection position (see a solid line of
FIG. 23) which is on an optical path X extending from an object to
the imaging unit 1 and a retracted position (see a chain
double-dashed line of FIG. 23) which is off the optical path X and
is located adjacent to the finder optical system 6. At the
reflection position, the quick return mirror 46 divides incident
light into reflected light toward the finder optical system 6 and
transmitted light to the back surface side of the quick return
mirror 46. The quick return mirror 46 serves as a movable mirror.
The reflection position corresponds to a first position, and the
retracted position corresponds to a second position.
[0356] Specifically, the quick return mirror 46 is arranged in
front of the shutter unit 42 (i.e., at an object side), and
pivotally supported about an axis Y which is located above and in
front of the shutter unit 42 and horizontally extends. The quick
return mirror 46 is biased toward a retracted position by a bias
spring (not shown). The quick return mirror 46 is moved to the
reflection position by the bias spring being wound up by a motor
(not shown) for opening and closing the shutter unit 42. The quick
return mirror 46 which has been moved to the reflection position is
engaged with an electromagnet or the like at the refection
position. Then, this engagement is released, thereby causing the
quick return mirror 46 to be pivotally moved to the retracted
position by force of the bias spring.
[0357] That is, to guide a part of incident light to the finder
screen 61, the bias spring is wound up by the motor, thereby
causing the quick return mirror 46 to be positioned at the
reflection position. To guide the entire incident light to the
imaging unit 1, the engagement with the electromagnet or the like
is released, thereby causing the quick return mirror 46 to be
pivotally moved to the retracted position by elastic force of the
bias spring.
[0358] As shown in FIGS. 24(A)-24(C), a light shielding plate 47 is
connected to the quick return mirror 46. The light shielding plate
47 is configured to interact with the quick return mirror 46, and
covers, when the quick return mirror 46 is positioned at the
retracted position, the quick return mirror 46 from below (i.e.,
from a side closer to the optical path X extending from the object
to the imaging unit 1). Thus, when the quick return mirror 46 is
positioned at the retracted position, light entering from the
finder optical system 6 is prevented from reaching the imaging unit
1. The light shielding plate 47 serves as a light shielding
section.
[0359] Specifically, the light shielding plate 47 includes a first
light shielding plate 48 pivotally connected to an end portion of
the quick return mirror 46 located at an opposite side to the pivot
axis Y, and a second light shielding plate 49 pivotally connected
to the first shielding plate 48. The first light shielding plate 48
includes a first cam follower 48a. In the camera body 204, a first
cam groove 48b with which the first cam follower 48a is to be
engaged is provided. The second light shielding plate 49 includes a
second cam follower 49a. In the camera body 204, a second cam
groove 49b with which the second cam follower 49a is to be engaged
is provided.
[0360] That is, when the quick return mirror 46 is pivotally moved,
the first light shielding plate 48 is moved to follow the quick
return mirror 46, and the second light shielding plate 49 is moved
to follow the first light shielding plate 48. In this case, the
first and second light shielding plates 48 and 49 move in
conjunction with the quick return mirror 46 while the first and
second cam followers 48a and 49a are guided respectively by the
first and second cam grooves 48b and 49b.
[0361] As a result, when the quick return mirror 46 is positioned
at the retracted position, as shown in FIG. 24(A), the first and
second light shielding plates 48 and 49 are arranged as a single
flat plate below the quick return mirror 46, thereby shielding
light between the quick return mirror 46 and the shutter unit 42,
i.e., the imaging unit 1. In this case, similarly to the quick
return mirror 46, the first and second light shielding plates 48
and 49 are located off the optical path X. Therefore, the first and
second light shielding plates 48 and 49 do not influence light
entering the imaging unit 1 from the object.
[0362] As the quick return mirror 46 is moved from the retracted
position to the reflection position, as shown in FIG. 24(B), the
first and second light shielding plates 48 and 49 arranged as a
single flat plane are bent. When the quick return mirror 46 is
pivotally moved to the reflection position, as shown in FIG. 24(C),
the first and second light shielding plates 48 and 49 are bent at
an angle that allows them to face each other. In this state, the
first and second light shielding plates 48 and 49 are off the
optical path X and are located at an opposite side to the finder
screen 61 across the optical path X. Therefore, when the quick
return mirror 46 is positioned at the reflection position, the
first and second light shielding plates 48 and 49 do not influence
light reflected toward the finder optical system 6 by the quick
return mirror 46 and light transmitting through the quick return
mirror 46.
[0363] As described above, with the semi-transparent quick return
mirror 46 and the shielding plate 47 provided, in the finder
shooting mode, the user can view an object image with the finder
optical system 6 before shooting is performed, and light can be
caused to reach the imaging unit 1. Also, when shooting is
performed, incident light from the finder optical system 6 can be
prevented from reaching the imaging unit 1 by the light shielding
plate 47 while light from an object is directed to the imaging unit
1. In the live view shooting mode, incident light from the finder
optical system 6 can be prevented from reaching the imaging unit 1
by the light shielding plate 47.
[0364] --Operation of Camera--
[0365] The camera 200 configured in the above-described manner has
the two shooting modes, i.e., the finder shooting mode and the live
view shooting mode that employ different methods for viewing an
object. The operations of the two shooting modes of the camera 200
will be described hereinafter.
[0366] --Finder Shooting Mode--
[0367] First, the shooting operation of the camera system in the
finder shooting mode will be described hereinafter with reference
to FIGS. 25 and 26.
[0368] The power switch 40a is turned on (Step Si1), the release
button 40b is pressed halfway down by a user (Step Si5), and then,
the release button 40b is pressed all the way down by the user
(Step Si11), so that the shutter unit 42 is temporarily put into a
close state (Step Si12). The above-described Steps Si1-Si12 are
basically the same as Steps Sa1-Sa12 in phase difference detection
AF of the first embodiment.
[0369] When the power switch 40a is turned on, the quick return
mirror 46 is positioned at the reflection position on the optical
path X. Thus, a part of light which has entered the camera body 204
is reflected and enters the finder screen 61.
[0370] Light which has entered the finder screen 61 is formed as an
object image. The object image is converted into an erected image
by the pentaprism 62, and enters the eye lens 63. That is, as
opposed to the first embodiment, the object image is not displayed
at the image display section 44, but the user can observe the
erected image of the object through the eye lens 63. In this case,
the object image is not displayed, but various pieces of
information regarding shooting are displayed at the image display
section 44.
[0371] Then, when the release button 40b is pressed halfway down by
the user (Step Si5), various pieces of information (such as
information regarding AF and photometry which will be described
later, and the like) regarding shooting are displayed at the
in-finder display section 64 which the user can observe through the
eye lens 63. That is, the user can identify each piece of
information regarding shooting by not only the image display
section 44 but also the in-finder display section 64.
[0372] In this case, since the quick return mirror 46 is
semi-transparent, a part of light which has entered the camera body
204 is directed to the finder optical system 6 by the quick return
mirror 46, but the rest of the light is transmitted through the
quick return mirror 46 to enter the shutter unit 42. Then, when the
shutter unit 42 is put into an open state (Step Si4), light
transmitted through the quick return mirror 46 enters the imaging
unit 1. As a result, viewing the object image through the finder
optical system 6 is allowed, and autofocusing by the imaging unit 1
(Steps Si6-Si8) and photometry (Step Si9) can be performed.
[0373] Specifically, in Steps Si6-Si8, phase difference detection
AF is performed based on an output from the phase difference
detection unit 20 of the imaging unit 1 and, in parallel with phase
difference detection AF, photometry can be performed based on an
output of the imaging device 10 of the imaging unit 1 in Step
Si9.
[0374] In phase difference detection in Step Si6, the object image
light is transmitted through the quick return mirror 46, and
accordingly, an optical length is increased by an amount
corresponding to the thickness of the quick return mirror 46. Thus,
a phase detection width of the phase difference detection section
defers between when the quick return mirror 46 is retracted from an
object image optical path and is put into an image capturing state
and when the quick return mirror 46 is positioned at a reflection
position. Therefore, in the finder shooting mode in which the quick
return mirror 46 is interposed in the object image optical path,
defocus information is output with a phase detection width obtained
by changing the phase detection width in phase difference focus
detection of the first embodiment (i.e., a phase detection width in
phase difference focus detection of hybrid AF in the live view
shooting mode which will be described later) by a predetermined
amount. Note that the phase detection width means a reference phase
difference used for determining that a calculated defocus amount is
0, i.e., an object is in focus.
[0375] Steps Si6-Si8 of performing phase difference detection AF is
the same as Steps Sa6-Sa8 in phase difference detection AF of the
first embodiment.
[0376] In Step Si9, the amount of light entering the imaging device
10 is measured by the imaging device 10. Note that in this
embodiment, as opposed to the first embodiment, not the entire
light from an object enters the imaging device 10, and therefore,
the body microcomputer 50 corrects an output from the imaging
device 10 based on reflection characteristics of the quick return
mirror 46 to obtain the amount of light from the object.
[0377] Then, after the release button 40b is pressed all the way
down by the user (Step Si11) and the shutter unit 42 is temporarily
put into a close state (Step Si12), in parallel with starting of
image blur correction (Step Si13) and stopping down of the aperture
section 73 (Step Si14), the quick return mirror 46 is flipped up to
the retracted position in Step Si15.
[0378] Thereafter, in Steps Si16-Si18, similarly to Steps Sa15-Sa17
in phase difference detection AF of the first embodiment, exposure
is performed.
[0379] After exposure is terminated, in parallel with terminating
of image blur correction (Step Si19) and opening of the aperture
section 73 (Step Si20), the quick return mirror 46 is moved to the
reflection position in Step Si21. Thus, the user can view an object
image through the finder optical system 6 again.
[0380] Thereafter, the shutter unit 42 is put into an open state
(Step Si22). When a shooting sequence is terminated after resetting
is completed, the process returns to Step Si5, and the body
microcomputer remains in a standby state until the release button
40b is pressed halfway down by the user.
[0381] Steps Si23-Si25 after the power switch 40a is turned off are
the same as Steps Sa21-Sa23 in phase difference detection AF of the
first embodiment.
[0382] As described above, the phase difference detection unit 20
for detecting a phase difference using light transmitted through
the imaging device 10 is provided to the imaging unit 1. Thus, even
with the configuration in which light from an object is directed to
the finder optical system 6 by the quick return mirror 46 and
thereby an object image can be viewed through the finder optical
system 6, phase difference detection AF and photometry can be
performed in parallel while allowing the object image to be viewed
through the finder optical system 6 by employing the
semi-transparent quick return mirror 46 and thus causing a part of
light entering the quick return mirror 46 to reach the imaging unit
1. Therefore, there is no need to additionally provide a reflecting
mirror for phase difference detection AF and a sensor for
photometry, and also, photometry can be performed in parallel with
autofocusing, so that a release time lag can be reduced.
[0383] --Live View Shooting Mode--
[0384] Next, the shooting operation of the camera system in a live
view shooting mode will be described with reference to FIGS. 27 and
28.
[0385] First, in steps (Steps Sj1-Sj4) from the step in which the
power switch 40a is turned on to the step in which the shutter unit
42 is put into an open state, the same operation as the operation
in hybrid AF of the first embodiment is performed.
[0386] In this case, in the camera 200, immediately after the power
switch 40a is turned on, the quick return mirror 46 is positioned
at the reflection position, and thus, in Step Sj5, the body
microcomputer 50 flips up the quick return mirror 46 to the
retracted position.
[0387] As a result, light entering the camera body 204 from an
object is not divided to be directed to the finder optical system
6, but passes, through the shutter unit 42, is transmitted through
the OLPF 43 serving also an IR cutter, and then, enters the imaging
unit 1. An object image formed at the imaging unit 1 is displayed
at the image display section 44, so that the user can observe the
object image through the image display section 44. A part of light
which has entered to the imaging unit 1 is transmitted through the
imaging device 10 and enters the phase difference detection unit
20.
[0388] Then, when the release button 40b is pressed halfway down by
the user (Step Sj6), as opposed to the finder shooting mode, hybrid
AF is performed. Steps Sj7, Sj8, Sj11 and Sj12 according to this
hybrid AF are the same as Steps Sc6, Sc7, Sc10 and Sc11 in hybrid
AF of the first embodiment.
[0389] Note that the autofocusing method employed in this case is
not limited to hybrid AF, but contrast detection AF or phase
difference detection AF may be performed.
[0390] In parallel with hybrid AF, photometry is performed (Step
Sj9), and image blur detection is started (Step Sj10). Steps Sj9
and Sj10 are the same as Steps Sc8 and Sc9 in hybrid AF of the
first embodiment.
[0391] Thus, when the release button 40b is pressed halfway down by
the user, various pieces of information regarding shooting (such as
information regarding AF and photometry and the like) are displayed
at the image display section 44.
[0392] Thereafter, the steps from the step (Step Sj13) in which the
release button 40b is pressed all the way down by the user to the
step (Step Sj22) in which exposure is terminated to complete
resetting are basically the same as Steps Si11-Si22 in the finder
shooting mode, except that the step (corresponding to Step Si15) of
moving the quick return mirror 46 to the retracted position after
the shutter unit 42 is put into a close state is not included, and
that the step (corresponding to Step Si21) of moving the quick
return mirror 46 to the reflection position after the shutter unit
42 is put into a close state to terminate exposure is not
included.
[0393] According to this embodiment, when the power switch 40a is
turned off (Step Sj23), the focus lens group 72 is moved to the
reference position (Step Sj24) and, in parallel with putting the
shutter unit 42 into a close state (Step Sj25), the quick return
mirror 46 is moved to the reflection position in Step Sj26.
Thereafter, respective operations of the body microcomputer 50 and
other units in the camera body 204, and the lens microcomputer 80
and other units in the interchangeable lens 7 are halted.
[0394] The shooting operation of the camera system in the live view
shooting mode is the same as the shooting operation of the camera
100 of the first embodiment, except the operation of the quick
return mirror 46. That is, although hybrid AF has been described in
the description above, various shooting operations according to the
first embodiment can be performed, and the same functional effects
and advantages as those of the first embodiment can be
achieved.
[0395] Therefore, according to this embodiment, the camera 200
further includes the finder optical system 6 provided to the camera
body 204 and the semi-transparent quick return mirror 46,
configured so that the position of the quick return mirror 46 can
be switched between the reflection position located on an optical
path from an object to the imaging device 10 and the retracted
position located off the optical path, for reflecting a part of
incident light at the reflection position to guide the part of the
incident light to the finder optical system 6 and causing the rest
of the incident light to pass therethrough to guide the rest of the
incident light to the imaging device 10. The body control section 5
is configured to be capable of switching a shooting mode between a
finder shooting mode in which shooting is performed in a state
where an object can be viewed through the finder optical system 6
and the live view shooting mode in which shooting is performed in a
state in which an object can be viewed through the image display
section. In the finder shooting mode, the quick return mirror 46 is
positioned at the reflection position to guide a part of incident
light to the finder optical system 6, thereby allowing an object
image to be viewed through the finder optical system 6, and the
rest of the incident light is guided to the imaging device 10 and
focus adjustment is performed based on a detection result of the
phase difference detection unit 20 which has received light which
has passed through the imaging device 10. In the live view shooting
mode, the quick return mirror 46 is positioned at the retracted
position to cause incident light from an object to enter the
imaging device 10, thereby causing the image display section 44 to
display an image based on an output of the imaging device 10, and
focus adjustment is performed at least based on a detection result
of the phase difference detection unit 20. Thus, in the camera 200
including the finder optical system 6, various types of processing
using the imaging device 10 can be performed in parallel with
autofocusing (the above-described phase difference detection AF or
hybrid AF) using the phase difference detection unit 20, regardless
of which of the finder shooting mode and the live view shooting
mode is selected, so that the processing time can be reduced and
also switching between the various types of processing using the
imaging device 10 and autofocusing the phase difference detection
unit 20 can be performed quickly and quietly. As a result, the
convenience of the camera 200 can be improved.
[0396] Moreover, with the semi-transparent quick return mirror 46
and the shielding plate 47 provided, in the finder shooting mode,
before shooting is performed, an object image can be viewed through
the finder optical system 6, and light can be caused to reach the
imaging unit 1. Also, when shooting is performed, incident light
from the finder optical system 6 can be prevented from reaching the
imaging unit 1 by the light shielding plate 47 while light from an
object is guided to the imaging unit 1. In the live view shooting
mode, incident light from the finder optical system 6 can be
prevented from reaching the imaging unit 1 by the light shielding
plate 47.
Other Embodiments
[0397] In connection with the above-described embodiments, the
following configurations may be employed.
[0398] Specifically, according to the second embodiment, the finder
optical system 6 is provided, but the present invention is not
limited thereto. For example, a configuration including an
electronic view finder (EVF), instead of the finder optical system
6, may be employed. More specifically, a compact image display
section comprised of a liquid crystal display or the like is
arranged in the camera body 204 to be located at a position where
the user can view the image display section through the finder, and
image data obtained in the imaging unit 1 is displayed at the image
display section. Thus, even if the complex finder optical system 6
is not provided, shooting while viewing through the finder can be
realized. In such a configuration, the quick return mirror 46 is
not necessary. The shooting operation is the same as that of the
camera 100 of the first embodiment, although two image display
sections are provided.
[0399] In each of the above-described first and second embodiments,
the configuration in which the imaging unit 1 is mounted on a
camera has been described. However, the present invention is not
limited thereto. For example, the imaging unit 1 can be mounted on
a video camera.
[0400] An example shooting operation of a video camera will be
described. When the power switch 40a is turned on, an aperture
section and a shutter unit are opened, and image capturing is
started in the imaging device 10 of the imaging unit 1. Then,
optimal photometry and white balance adjustment for displaying a
live view are performed, and a live view image is displayed at the
image display section. Thus, in parallel with image capturing by
the imaging device 10, an in-focus state is detected based on an
output of the phase difference detection unit 20 mounted in the
imaging unit 1 and driving of the focus lens group is continued
according to the movement of an object or the like. In this manner,
the video camera remains in a standby state until a REC button is
pressed while continuing to display a live view image and to
perform phase difference detection AF. When the REC button is
operated, image data captured by the imaging device 10 is recorded
while phase difference detection AF is repeated. Thus, an in-focus
state can be maintained at all the time, and as opposed to a known
digital camera, micro driving of a focus lens in an optical
direction (wobbling) does not have to be performed, so that an
actuator such as a motor and the like, which has a large electric
load, does not have to be driven.
[0401] Also, the configuration in which when the release button 40b
is pressed halfway down by the user (i.e., the S1 switch is turned
on), AF is started has been described. However, AF may be performed
before the release button 40b is pressed halfway down. Moreover,
the configuration in which AF is terminated when it is determined
that an object image has been brought into focus has been
described. However, AF may be continued after focus determination,
and also AF may be continuously performed without performing focus
determination. A specific example will be described hereinafter. In
FIGS. 11 and 12, after the shutter unit 42 is opened in Step Sa4,
phase difference focus detection of Step Sa6 and focus lens driving
of Step Sa1 are performed repeatedly. In parallel with this
operation, determination of Step Sa5, photometry of Step Sa9, image
blur detection of Step Sa10, and determination of Step Sa11 are
performed. Thus, an in-focus state can be achieved even before the
release button 40b is pressed halfway down by the user. For
example, by using this operation with live view image display,
display of a live view image in an in-focus state is allowed. If
phase difference detection AF is used, live view image display and
phase difference detection AF can be used together. The
above-described operation may be added as a "continuous AF mode" to
the function of a camera. A configuration in which the "continuous
AF mode" is changeable between on and off may be employed.
[0402] In each of the above-described first and second embodiments,
the configuration in which the imaging unit 1 is mounted in a
camera has been described. However, the present invention is not
limited to the above-described configuration. The camera in which
the imaging unit 1 is mounted is an example of cameras in which
exposure of an imaging device and phase difference detection by a
phase difference detection unit can be simultaneously performed. A
camera according to the present invention is not limited thereto,
but may have a configuration in which object light is guided to
both of an imaging device and a phase difference detection unit,
for example, by an optical isolation device (such as, for example,
a prism, a semi-transparent mirror, and the like) for isolating
light to the image device. Moreover, a camera in which a part of
each microlens of an imaging device is used as a separator lens and
is arranged so that pupil-divided object light can be received at
light receiving sections may be employed.
[0403] Note that the above-described embodiments are essentially
preferable examples which are illustrative and do not limit the
present invention, its applications and the scope of use of the
invention.
INDUSTRIAL APPLICABILITY
[0404] As has been described, the present invention is useful
particularly for an imaging apparatus including an imaging device
for performing photoelectric conversion.
* * * * *