U.S. patent application number 10/695417 was filed with the patent office on 2005-02-17 for camera and portable equipment with camera.
This patent application is currently assigned to SANKYO SEIKI MFG. CO., LTD.. Invention is credited to Yajima, Masao, Yasuda, Sadayoshi.
Application Number | 20050036776 10/695417 |
Document ID | / |
Family ID | 34101134 |
Filed Date | 2005-02-17 |
United States Patent
Application |
20050036776 |
Kind Code |
A1 |
Yasuda, Sadayoshi ; et
al. |
February 17, 2005 |
CAMERA AND PORTABLE EQUIPMENT WITH CAMERA
Abstract
A camera includes a lens driving device and an image obtaining
device. The lens driving device is formed from a lens holder that
holds a lens and a driving device that moves the lens holder in an
optical axis of the lens, wherein the lens holder is intermittently
stoppable at least at two positions in the optical axis direction
of the lens. The image obtaining device captures optical images of
different magnifications at least at the two positions, and obtains
zoom images at least between one of the optical images and the
other of the optical images based on at least one of the optical
images and electronic images generated based on the at least one of
the optical images.
Inventors: |
Yasuda, Sadayoshi; (Nagano,
JP) ; Yajima, Masao; (Nagano, JP) |
Correspondence
Address: |
HOGAN & HARTSON L.L.P.
500 S. GRAND AVENUE
SUITE 1900
LOS ANGELES
CA
90071-2611
US
|
Assignee: |
SANKYO SEIKI MFG. CO., LTD.
|
Family ID: |
34101134 |
Appl. No.: |
10/695417 |
Filed: |
October 27, 2003 |
Current U.S.
Class: |
396/72 ;
348/E5.028; 348/E5.042 |
Current CPC
Class: |
G02B 13/004 20130101;
H04N 5/23293 20130101; G02B 13/009 20130101; H04N 5/23296 20130101;
G02B 13/0035 20130101; H04N 5/2254 20130101 |
Class at
Publication: |
396/072 |
International
Class: |
G03B 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 13, 2003 |
JP |
2003-292821 |
Claims
1. A camera comprising: a lens driving device including a lens
holder that holds a lens and a driving device that moves the lens
holder in an optical axis of the lens, wherein the driving device
includes a drive coil and a drive magnet for moving the lens
holder, and wherein the lens holder is intermittently stoppable at
least at two predetermined stop positions in the optical axis
direction of the lens and is unable to stop other than said at
least two predetermined stop positions by means of the magnetic
action between the drive coil and the drive magnet; and an image
obtaining device that captures optical images of different
magnifications at the at least two predetermined stop positions,
and obtains electronic zoom images between said at least two
predetermined stop positions based on the captured optical images
at the at least two predetermined stop positions.
2. A camera according to claim 1, wherein the lens driving device
moves the lens holder to two positions, and the image obtaining
device captures first and second optical images of different
magnification at the two positions, and obtains zoom images between
the first and second optical images based on the first optical
image and electronic images generated based on the first optical
image.
3. A camera according to claim 1, wherein the image obtaining
device obtains at least a wide angle image at a wide angle
position, a telephoto image at a telephoto position and an
intermediate image at an intermediate position between the wide
angle position and the telephoto position, and the image obtaining
device generates enlarged zoom images up to immediately before the
intermediate position through processing the wide angle image and
obtains enlarged zoom images past the intermediate position and up
to the telephoto position through processing the image captured at
the intermediate position.
4. A camera according to claim 1, wherein the wide angle image and
the intermediate image are a wide angle optical image and an
intermediate optical image captured by the image obtaining device,
respectively, and the image obtaining device electronically
processes the wide angle optical image and the intermediate optical
image to obtain the zoom Images.
5. A camera according to claim 1, wherein the image obtaining
device obtains zoom images between one of the optical images and
the other of the optical images based on both of the optical images
and electronic images generated based on both of the optical
images.
6. A camera according to claim 1, wherein the image obtaining
device obtains enlarged zoom images based on one of the optical
images and reduced zoom images based on the other of the optical
images.
7. A camera according to claim 4, wherein the image obtaining
device obtains zoom images between the wide angle optical image and
the intermediate optical image, wherein the zoom images include
enlarged zoom images generated based on the wide angle optical
image and reduced zoom images generated based on the intermediate
optical image.
8. A camera according to claim 1, wherein the lens driving device
stops the lens holder only at two places, and the image obtaining
device captures the optical images at the two places.
9. A camera comprising: a lens driving device having a lens holder
that holds a lens, and a driving device that moves the lens holder
in an optical axis of the lens, wherein the driving device includes
a drive coil and a drive magnet for moving the lens holder; and an
image obtaining device that obtains zoom images at least through
continuous image processing between a wide angle position and a
telephoto position of different magnifications, wherein the lens
holder is intermittently stopped at least at two predetermined stop
positions to capture an optical image at the wide angle position
and an optical image at the intermediate position, and wherein the
lens holder is unable to stop other than said at least two
predetermined stop positions by means of the magnetic action
between the drive coil and the drive magnet, and wherein the image
obtaining device obtains enlarged zoom images past the wide angle
position and up to immediately before the intermediate position
through electronically processing the optical image taken at the
wide angle position and obtains enlarged zoom images past the
intermediate position and up to the telephoto position through
electronically processing the optical image taken at the
intermediate position.
10. A camera according to claim 9, wherein the lens driving device
stops the lens holder only at the wide angle position and the
intermediate position, and the image obtaining device captures the
optical images at the wide angle position and the intermediate
position.
11. A camera according to claim 9, wherein the image obtaining
device obtains enlarged zoom images between the wide angle position
and the intermediate position through electronically processing the
optical images captured at the wide angle position and the
intermediate position.
12. A camera according to claim 11, wherein the image obtaining
device further obtains enlarged images based on the optical image
taken at the intermediate position and electronic images obtained
through electronically processing the optical image taken at the
intermediate position.
13. A camera comprising: a lens driving device including a lens
holder that holds a lens and a driving device that moves the lens
holder in an optical axis of the lens, wherein the driving device
includes a drive coil and a drive magnet for moving the lens
holder, and wherein the lens holder is intermittently stoppable at
least at a first position on a wide angle side and a second
position on a telephoto side that provides a magnification greater
than a magnification on the wide angle side, and wherein the lens
holder is unable to stop other than at least at said first and
second predetermined stop positions by means of the magnetic action
between the drive coil and the drive magnet; and an image obtaining
device that captures optical images with different magnifications
and obtains zoom images between one of the optical images and
another of the optical images based on the optical images with
different magnifications and electronic images obtained by
electronically processing the optical images, wherein the image
obtaining device captures an optical image at the first position
and uses the optical image captured to form enlarged zoom images
when an image enlargement zooming between the first and second
positions is instructed, and captures an optical image at the first
position and uses the optical image captured to form reduced zoom
images when an image reduction zooming between the first and second
positions is instructed.
14. A camera according to claim 13, wherein the image obtaining
device includes a zoom instruction read device that reads a zoom
instruction and an operational position confirmation device that
confirms an operation position of the lens required for the zoom
instruction.
15. A camera according to claim 14, wherein the lens holder is
driven by the lens driving device to the operation position
confirmed by the operational position confirmation device.
16. A camera according to claim 14, wherein the lens holder is not
driven by the lens driving device when the operation position
confirmed by the operational position confirmation device is a
current position of the lens.
17. A camera according to claim 14, wherein the image obtaining
device includes a current position detection device that detects a
current position of the lens, and when the operation position is on
the wide angle side, the current position detection device detects
whether the current position of the lens is the first position, and
the lens driving device moves the lens to the first position to
capture an optical image when the current position is not the first
position, and does not move the lens such that the lens remains
unmoved to capture an optical image if the current position is the
first position.
18. A camera according to claim 17, wherein, when the operational
position is on the telephoto side, the current position detection
device detects whether the current position of the lens is the
second position, and the lens driving device moves the lens to the
second position when the current position is not the second
position, and does not move the lens such the lens remains unmoved
to capture an optical image when the current position is the second
position.
19. A camera according to claim 14, wherein, when the zoom
instruction read device receives a zoom instruction of an image
zooming with an enlargement magnification, the image obtaining
device moves the lens to the second position before the enlargement
magnification reaches the optical magnification in the second
position, captures an optical image in the second position in
advance, then forms an image for displaying a second enlargement
zoom image formed base on the optical image captured in the second
position after displaying a first enlargement zoom image formed
base on the optical image captured in the first position, such that
enlarged zoom images between the first position and the second
position are obtained based on the first zoom image and the second
zoom image.
20. A camera according to claim 19, wherein the second zoom image
is obtained by placing an enlarged image obtained by electronically
processing the optical image captured in the first position on a
peripheral area of the optical image captured in the second
position.
21. A portable equipment with camera comprising: a camera recited
in claim 1; and a display device for displaying images obtained by
the camera.
22. A portable equipment with camera comprising: a camera recited
in claim 9; and a display device for displaying images obtained by
the camera.
23. A portable equipment with camera comprising: a camera recited
in claim 13; and a display device for displaying images obtained by
the camera.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to cameras and portable
equipment with camera.
[0003] 2. Related Background Art
[0004] Thin cameras that may be mounted on portable telephones with
camera have shorter lens moving distance for focus and zoom
adjustments in photographing compared to other ordinary cameras.
For this reason, lens driving devices that magnetically drive the
lens directly are suitable for use as lens driving devices applied
to such cameras.
[0005] Among such lens driving devices of the magnetic drive type,
the following, for example, are known. A lens driving device that
has been suggested includes a cylindrical lens holder for holding a
lens, a ring-shaped rotor magnet mounted on the outer circumference
of the lens holder, and a drive coil that opposes the rotor magnet.
By controlling the energization of the drive coil, the lens holder
holding the lens is directly moved linearly in the optical axis
direction to a predetermined position without the intervention of
any conversion mechanism and magnetically held in the position.
[0006] Another type of lens driving device that uses a guide shaft
that guides a lens holder holding a lens along the optical axis is
known as an example of utilizing a conversion mechanism that
converts a motor's rotational force into linear motion.
[0007] When taking a picture by a portable phone with camera, the
portable phone is often held with one hand to take a picture of the
holder's face or other subjects in close proximity. For this
reason, photographic lenses used in this type of camera often have
a close-up photographing function. In photographic lenses having
such a close-up photographing function, the lens position for
ordinary photographing and the lens position for close-up
photographing, or macro photographing, are different. In other
words, the lens position for close-up photographing is slightly
closer to subject by a predetermined distance compared to the lens
position for ordinary photographing.
[0008] As a result, this type of photographing lenses is provided
with a driving source for moving the lens position between the
ordinary photographing position and the macro photographing
position, and the driving source is driven with a switch to move
the lens between the two points of photographing positions.
However, it is difficult to utilize a motor as a driving source on
portable equipment such as portable telephones, due to the need to
miniaturize the equipment and achieve lighter weight. Furthermore,
since photographing takes place only in two positions, a lens
driving device in which electromagnetic force is directly applied
to the lens drive to move the lens is desirable.
[0009] However, in the conventional lens driving devices in which a
lens holder is magnetically moved without a force conversion
system, subtle positional controls that are required when executing
zoom operations to enlarge or reduce an image are extremely
difficult. Furthermore, since the drive coil is energized and
excited to hold the lens holder in position, when the energization
ceases, the lens holder is released from its position.
Consequently, there is an additional problem of the lens position
shifting as a result of external force and vibration when the
energization ceases. On the other hand, always supplying power
would result in large power consumption, which would make it
impossible to mount the lens driving device on portable equipment
such as portable telephones.
[0010] Moreover, in a lens drive mechanism in which rotational
motion is converted into linear motion, although positional control
during zoom operations is easy, the force transmission mechanism
and conversion mechanism from the motor mechanism to the lens
holder become complicated, which can result in poor assembly
efficiency and a large device with a built-in lens drive
mechanism.
SUMMARY OF THE INVENTION
[0011] The present invention has been conceived to solve the
problems described above, and relates to cameras and portable
equipment with camera, with which superior zoom display can be
performed using a relatively simple mechanism.
[0012] In accordance with an embodiment of the present invention, a
camera includes a lens driving device including a lens holder that
holds a lens and a driving device that moves the lens holder in an
optical axis of the lens, wherein the lens holder is intermittently
stopped at least at two positions in an optical axis direction of
the lens, and an image obtaining device that captures optical
images of different magnifications at the at least two positions,
and obtains zoom images between one of the optical images and the
other of the optical images based on at least one of the optical
images and electronic images generated based on the at least one of
the optical images.
[0013] According to the present embodiment, the lens holder is not
continuously stoppable but rather intermittently stoppable. As a
result, the structure for stopping the lens holder is not
complicated. Furthermore, due to the fact that optical images taken
at the stop positions of the lens holder can be used to obtain
images with different optical magnifications between the stop
positions, enlarged and reduced zoom images between the stop
positions can be easily obtained. In addition, since an optical
image is captured at each of the stop positions, displays based on
superior images can be made at both the beginning and end of
zooming. As a result, zoom displays can be made in excellent
quality with a relatively simple mechanism.
[0014] In accordance with another embodiment of the present
invention, a camera includes a lens driving device including a lens
holder that holds a lens and a driving device that moves the lens
holder in an optical axis of the lens, and an image obtaining
device that obtains zoom images at least through continuous image
processing between a wide angle position and a telephoto position
of different magnifications. In one aspect, the lens holder is
intermittently stopped at at least two positions, for example, at
the wide angle position and an intermediate position between the
wide angle position and the telephoto position, to capture an
optical image at the wide angle position and an optical image at
the intermediate position; and the image obtaining device obtains
enlarged zoom images past the wide angle position and up to
immediately before the intermediate position through electronically
processing the optical image taken at the wide angle position and
obtains enlarged zoom images past the intermediate position and up
to the telephoto position through electronically processing the
optical image taken at the intermediate position.
[0015] According to this embodiment, the lens holder is not
continuously stoppable but rather intermittently stoppable. As a
result, the structure for stopping the lens holder is not
complicated. In addition, enlarged zoom images from the wide angle
position to the intermediate position can be obtained based on the
optical images taken at the wide angle position and the
intermediate position and electronic images obtained through
electronic processing of these optical images, and further enlarged
images can be obtained based on the optical image taken at the
intermediate position and electronic images obtained through
electronically processing the optical image taken at the
intermediate position. Consequently, enlarged zoom images with
superior display quality can be obtained over a wide range.
[0016] In accordance with another embodiment of the present
invention, a camera includes a lens driving device including a lens
holder that holds a lens and a driving device that moves the lens
holder in an optical axis of the lens wherein the lens holder is
configured to be intermittently stoppable in at least two positions
in the optical axis direction, e.g., a first position on a wide
angle side and a second position on a telephoto side whose
magnification is greater than the magnification on the wide angle
side, and an image obtaining device that captures optical images
with different magnifications and obtains zoom images between one
of the optical images and another of the optical images based on
the optical images with different magnifications and electronic
images obtained by electronically processing the optical images. In
one aspect, the image obtaining device captures an optical image at
the first position and utilizes the optical image to form enlarged
zoom images when an image enlargement zooming between the two
positions is instructed, and also captures an optical image at the
first position and utilizes the optical image to form reduced zoom
images when an image reduction zooming between the two positions is
instructed.
[0017] According to this embodiment, the lens holder is not
continuously stoppable but rather intermittently stoppable. As a
result, the structure for stopping the lens holder is not
complicated. In addition, since zoom images between the wide angle
side and the telephoto side are obtained based on the optical
images taken at the wide angle and telephoto positions and the
electronic images between the wide angle position and the telephoto
position, a superior zoom image display can be performed with a
simple mechanism.
[0018] Since the optical image in the first position on the wide
angle side is used in both enlargement zooming and reduction
zooming, an image with a wide angle of view, or an image with a
large amount of information, can be used. This allows images both
in enlargement and reduction to be displayed smoothly.
[0019] In accordance with another embodiment of the present
invention, in addition to the camera described above, the image
obtaining device may preferably include a zoom instruction read
device for reading zoom instructions and an operational position
confirmation device for confirming the current lens operation
position, such that when a zoom instruction is read by the zoom
instruction read device, the lens is driven by the lens driving
device to the position read by the operational position
confirmation device.
[0020] According to this embodiment, the operation of driving the
lens is performed efficiently, since the lens is driven only when
necessary based on reading the zoom instruction and confirming the
current position of the lens. Furthermore, since zooming takes
place after the lens is returned to its correct position, a proper
image is captured.
[0021] In accordance with another embodiment of the present
invention, in addition to the camera described above, the image
obtaining device may preferably include a current position
detection device for detecting the current position of the lens,
such that if the operational position is on the wide angle side,
the current position detection device detects whether the current
position of the lens is the first position, and if the current
position is not the first position, the lens is moved to the first
position by the lens driving device, and if the current position is
the first position, the lens remains in place and an optical image
is captured in the first position in both cases; on the other hand,
if the operational position is on the telephoto side, the current
position detection device detects whether the current position of
the lens is the second position, and if the current position is not
the second position, the lens is moved to the second position by
the lens driving device, and if the current position is the second
position, the lens remains in place and an optical image is
captured in the second position in both cases.
[0022] According to this embodiment, due to the current position
detection device for detecting the current position of the lens,
the lens can be driven or not driven depending on the detection
result, which translates into an efficient lens driving.
[0023] If an image enlargement zooming is instructed, the image
obtaining device may preferably move the lens to the second
position before the enlargement magnification reaches the optical
magnification in the second position, capture an optical image in
the second position in advance, and form an image for displaying a
second enlargement zoom image formed by utilizing the optical image
captured in the second position after displaying a first
enlargement zoom image utilizing an optical image captured in the
first position, such that enlarged zoom images from the first
position to the second position are obtained based on the first
zoom image and the second zoom image.
[0024] According to this embodiment, deterioration of the quality
of enlarged images obtained through electronic processing can be
prevented to a large extent. In other words, since the second zoom
image following the first zoom image is formed by utilizing an
optical image that is captured at the second position which is
equivalent to an enlargement image to be attained from the optical
image captured in the first position, there is a large amount of
information that can be used to create a superior image.
[0025] The second zoom image may preferably be obtained by placing
an enlarged image obtained by electronically processing the optical
image captured in the first position on a peripheral area of the
optical image captured in the second position.
[0026] As a result, the image quality in the center part of the
second zoom image, which requires high image quality since it is
the part where users' eyes tend to look at, improves and therefore
eliminates an impression that something is out of place when a
viewer who is looking at the electronic zoom image sees the optical
image that follows. This makes it possible to achieve a more
natural zoom display.
[0027] A portable equipment with camera in accordance with another
embodiment of the present invention includes one of the cameras
described above and a display device for displaying images captured
or obtained by the camera.
[0028] According to the present embodiment, since a superior zoom
display is possible in spite of a simple mechanism, miniaturization
and operational stabilization of portable equipment can be readily
achieved. Furthermore, due to the fact that the quality of the zoom
display is superior and that the zooming range can be widened, the
added value can be boosted for the portable equipment with
camera.
[0029] A camera according to the present invention can achieve a
superior zoom display with a relatively simple mechanism.
Furthermore, portable equipment with camera according to the
present invention can perform a superior zoom display with a
relatively simple mechanism and achieve miniaturization and
operational stabilization.
[0030] Other features and advantages of the invention will be
apparent from the following detailed description, taken in
conjunction with the accompanying drawings that illustrate, by way
of example, various features of embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a cross-sectional view of a lens driving device in
accordance with a first embodiment of the present invention which
is to be assembled into a camera.
[0032] FIG. 2 is an exploded perspective view of the lens driving
device in FIG. 1.
[0033] FIG. 3 is a plan view of a drive magnet used in the lens
driving device in FIG. 1.
[0034] FIGS. 4(a) and 4(b) are diagrams illustrating the movement
of a second lens group in the lens driving device in FIG. 1.
[0035] FIG. 5 is a block diagram of the system configuration of a
camera including the lens driving device in FIG. 1.
[0036] FIG. 6 is a flow chart of an operation for performing a
digital zoom using the lens driving device in FIG. 1.
[0037] FIG. 7 is a flow chart of another example of an operation
for performing a digital zoom using the lens driving device in FIG.
1.
[0038] FIG. 8 is a flow chart of another example of an operation
for performing a digital zoom using the lens driving device in FIG.
1.
[0039] FIGS. 9(a)-9(c) are diagrams illustrating an example of an
electronic image as a composite that is formed by the operational
flow in FIG. 8.
[0040] FIGS. 10(a)-10(e) are diagrams illustrating another example
of electronic images formed by the operational flow in FIG. 8.
[0041] FIG. 11 is a cross-sectional view of a lens driving device
in accordance with a second embodiment of the present invention
that is to be assembled into a camera.
[0042] FIGS. 12(a) and 12(b) are diagrams illustrating the
prevention of image quality deterioration in each of the lens
driving devices used in cameras according to the present invention,
wherein FIG. 12(a) is a diagram for the lens driving device
according to the first embodiment of the present invention, and
FIG. 12 (b) is a diagram for the lens driving device according to
the second embodiment of the present invention.
[0043] FIGS. 13 (a) and (b) are diagrams illustrating positional
relationship in the optical axis direction of various lenses in the
lens driving device in FIG. 11, and their movements.
[0044] FIG. 14 is a block diagram of the system configuration of
another example of a camera in accordance with an embodiment of the
present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0045] Cameras and portable equipment with camera in accordance
with preferred embodiments of the present invention will be
described below with reference to the accompanying drawings. In the
following, the description is primarily focused on lens driving
devices of cameras. The cameras (and lens driving devices)
according to various embodiments are structured to be suitable for
mounting as camera sections of portable equipment such as portable
telephones (i.e., cellular phones), but they may also be mounted on
other portable equipment such as PDAs (personal digital
assistants).
[0046] A lens driving device 1 according to the first embodiment
shown in FIGS. 1 through 10 primarily includes a moving body 10 and
a fixed body 24. The fixed body 10 has a lens-barrel 12, which is a
generally cylindrical lens holder in the center of which an optical
axis 11 is positioned, and inside the lens-barrel 12 is a lens 13,
which is a second lens group. The lens 13 may be composed of a
combination of a plurality of lenses or a single lens. On the top
side (i.e., the subject side) of FIG. 1 is positioned a lens 14,
which is a first lens group, while on the bottom side (i.e., the
camera body side) is positioned a lens 15, which is a third lens
group.
[0047] The lens 14, which is the first lens group, is affixed to a
cover 42, and the lens 15, which is the third lens group, is
affixed to the fixed body 24. Only the lens 13, which is the second
lens group, is movable forward and backward in the optical axis
direction to define a telephoto position (FIG. 4 (a)) and a wide
angle position (FIG. 4 (b)). In front of the lens 14, which is the
first lens group, a freely opening/closing barrier for lens
protection may be provided, although its illustration is
omitted.
[0048] The outer circumference of the lens-barrel 12 is formed such
that it has a large diameter on the front side and a small diameter
on the rear side, with a step section formed at the boundary
between the two. On the small diameter section on the rear side is
mounted a drive magnet 16. The drive magnet 16 abuts the step
section and affixed in a unitary fashion to the lens-barrel 12. The
drive magnet 16 protrudes outward from the outer circumference
surface of the lens-barrel 12 as if it were a flange section of the
lens-barrel 12.
[0049] On a front end section of the lens-barrel 12, i.e. an end
section on the subject side, is provided with a circular light
incident window 18, which introduces reflected light from the
subject into the lens 13, in the center of a front end surface 20.
The light incident window 18 may be larger than as shown in FIG. 1
or positioned forward of the lens 14, which is the first lens
group.
[0050] The lens-barrel 12 is inserted into the fixed body 24. The
fixed body 24 is also formed in a generally cylindrical shape, and
the outer circumference of a rear end section 22 of the lens-barrel
12 is mounted in a rear end section inner circumference 25 of the
fixed body 24 in a manner movable in the direction of the optical
axis 11 of the lens 13, with the rear end section inner
circumference 25 of the fixed body 24 as its guide. An inner end
side, or the limit of movement for the lens-barrel 12 towards the
camera body side, is determined by a rear end surface of the
lens-barrel 12 abutting a concave-shaped bottom surface 27, which
is formed facing inward on the rear end of a cylindrical section 26
that forms the fixed body 24. FIG. 1 shows a state in which the
lens-barrel 12 has moved to the inner most end side.
[0051] The drive magnet 16 that moves in a unitary fashion with the
lens-barrel 12 is ring-shaped as shown in FIGS. 2 and 3. A part of
the drive magnet 16 surrounding a center hole 16a is magnetized
with a single pole of N pole, while the entire outer circumference
part is magnetized with a single pole of S pole. The N and S poles
may have a reverse magnetization relationship. The drive magnet 16
is placed forward of the rear end section inner circumference 25 of
the cylindrical section 26 and opposite the inner circumference of
the cylinder 26, whose inner diameter is larger than the diameter
of the rear end section inner circumference 25, across a small gap.
Furthermore, the drive magnet 16 is housed in a manner movable with
respect to the cylindrical section 26 in the direction of the
optical axis 11.
[0052] At the inner end side of the fixed body 24 and at the center
of the concave section that surrounds the bottom surface 27 is
fixed the lens 15, which is the third lens group, by adhesive. On
the inner circumference of the fixed body 24 and on the inner end
side than the drive magnet 16 is placed a first drive coil 28,
which is wound in a ring shape to oppose the drive magnet 16; and a
second drive coil 30 is placed to interpose the drive magnet 16
with the first drive coil 28.
[0053] A ring-shaped first magnetic member 32 is mounted on the
inner end side of the first drive coil 28, and the first magnetic
member 32 and the first drive coil 28 are both affixed to the
cylindrical section 26 of the fixed body 24 by adhesive. As
described above, the front end surface of the first drive coil 28
and the rear end surface of the drive magnet 16 oppose each
other.
[0054] As described above, the second drive coil 30, which is wound
around in a circular ring shape, is mounted in a position forward
of the drive magnet 16 on the inner circumference of the front end
section of the fixed body 24, and a ring-shaped second magnetic
member 34 is mounted together with the drive coil 30 and affixed to
the cylindrical section 26 of the fixed body 24 by adhesive. The
front end surface of the drive magnet 16 and the rear end surface
of the second drive coil 30 oppose each other. Accordingly, the
first magnetic member 32 and the second magnetic member 34 are
placed on the outer end surfaces in the optical axis direction of
the first drive coil 28 and the second drive coil 30, respectively,
that are aligned in the direction of the optical axis 11 with the
drive magnet 16 being interposed between them. Furthermore, the
drive magnet 16 is interposed by the first and second drive coils
28 and 30 in the direction of the optical axis 11.
[0055] The first and second magnetic members 32 and 34 are each
made of a ferromagnetic member in a washer shape, such as a steel
plate, for example. The magnetic flux generated by the drive magnet
16 passes through the first drive coil 28 and the first magnetic
member 32 from their center towards the outer circumference side
and returns to the drive magnet 16. The magnetic flux generated by
the drive magnet 16 also passes through the second magnetic member
34 and the second drive coil 30 from their center towards the outer
circumference side and returns to the drive magnet 16, and these
members described above constitute a magnetic circuit.
Consequently, the first and second drive coils 28 and 30 are
positioned within a magnetic field formed by the drive magnet
16.
[0056] The distance between opposing surfaces of the first and
second drive coils 28 and 30 is larger than the thickness of the
drive magnet 16 in the direction of the optical axis 11, and a gap
is formed between the drive magnet 16 and the first drive coil 28
or between the drive magnet 16 and the second drive coil 30 in the
direction of the optical axis 11, and the drive magnet 16, and
therefore the lens-barrel 12 that moves in a unitary fashion with
the drive magnet 16, can move in the direction of the optical axis
11 within the range of this gap.
[0057] According to the first embodiment, the drive magnet 16 along
with the lens-barrel 12 shifts to the inner end side and is
retained at the shifted position by the magnetic attractive force
between the drive magnet 16 and the first magnetic member 32, as
shown in FIG. 1, even without any energization of the drive coils
28 and 30. The position of the lens 13 is in a photographing
position in wide angle (hereinafter called a "wide angle
position"). In this position, as shown in FIG. 1, there is a small
gap between the first drive coil 28 and the drive magnet 16. If the
first drive coil 28 and the drive magnet 16 collide with each
other, one or both would be damaged, and the small gap between them
prevents such collision.
[0058] In the state shown in FIG. 1, when a predetermined zoom
switch (not shown) is operated to switch to an enlargement, at
least one of the first and second drive coils 28 and 30 is
energized in the predetermined direction, and the direction of the
current and the direction of the magnetic field generated by the
drive magnet 16 cause the activation of an electromagnetic force in
a direction to push the drive magnet 16 forward based on Fleming's
left-hand rule, so that the drive magnet 16 along with the
lens-barrel 12 moves forward. The amount of forward movement is
defined by a range of the gap between the drive magnet 16 and one
of the first and second drive coils 28 and 30. When the lens-barrel
12 along with the lens 13 advances forward, the new position is a
photographing position in telephoto (hereinafter called a
"telephoto position").
[0059] It is noted that Fleming's left-hand rule represents the
relationship between a magnetic field, a line current circulating
in the magnetic field and a force that works on an object that
circulates the line current. According to the present embodiment,
since the drive coils 28 and 30 are both fixed, a force is applied
to the drive magnet 16 as a counter action. Between the wide angle
position and the telephoto position, enlarged zoom images are
formed through an electronic processing described later.
[0060] When the lens-barrel 12 advances forward, the forward
advancement is stopped by the front end surface 20's colliding into
a positioning protrusion 36, described later. The position of the
lens 13 when it has advanced forward is maintained by the magnetic
attractive force between the drive magnet 16 and the second
magnetic member 34, even without any energization of the drive
coils 28 and 30. In this state as well, a small gap is formed
between the second drive coil 30 and the drive magnet 16. This gap
also serves to prevent the second drive coil 30 and the drive
magnet 16 from colliding into each other and damaging one or
both.
[0061] The electromagnetic force generated when the lens-barrel 12
moves forward is generated in the direction to move the drive
magnet 16 forward when the first drive coil 28 is energized, and in
the direction to move the drive magnet 16 forward also when the
second drive coil 30 is energized. The first and second drive coils
28 and 30 may both be energized simultaneously, or one or the other
may be energized.
[0062] The positioning protrusion 36 is formed on the surface of
the fixed body 24 to oppose the front end surface 20 of the
lens-barrel 12 and to ensure positioning precision of the
lens-barrel 12 when the electromagnetic force causes the
lens-barrel 12 to advance forward. The positioning protrusion 36
may be formed as a plurality of protrusions on a surface of the
circular, pan-shaped cover 42 that makes up the fixed body 24 to
oppose the moving body 10. The cover 42 serves to receive the light
from the subject with the lens 14, which is the first lens group
fixed to the cover 42, and to pass the light towards the lens 13.
In addition, the cover 42 serves a function of preventing external
dust and dirt from entering the lens 13 side; the cover 42 is
mounted on the cylindrical section 26 of the fixed body 24 and is
fixed to the cylinder 26 by adhesive.
[0063] On the inner end side along the optical axis 11 of the lens
driving device 1, a filter 43 is positioned on a rear end member
46, which is fixed to a base section 47, described later; and
further to the inner end is fixed and placed an image capturing
element 44. The filter 43 serves to block lights of predetermined
wavelengths in accordance with the detection wavelength of the
image capturing element 44. The image capturing element 44 may be
composed of CMOSs (Complimentary Metal Oxide Semiconductors) and
sends its detected signal to a circuit substrate 45. Image signal,
which is the detection signals, are sent to a control section
(which may be composed of a microcomputer) placed on the circuit
substrate 45.
[0064] The circuit substrate 45 may be smaller in size or outer
diameter than the outer diameter of the cylindrical section 26 that
makes up the fixed body 24, so that the circuit substrate 45 would
not project outside the cylindrical section 26. It is noted that,
aside from CMOS, CCD or VMIS may be used for the image capturing
element 44.
[0065] To switch from the telephoto position to the wide angle
position, the zoom switch is switched to the reduction side. By
switching in this way, at least one of the first and second drive
coils 28 and 30 is energized in the reverse direction, and the
direction of the current and the direction of the magnetic field
generated by the drive magnet 16 activate an electromagnetic force
in the direction to pull the drive magnet 16 backward based on
Fleming's left-hand rule, so that the drive magnet 16 along with
the lens-barrel 12 moves rearward and the lens position goes into
the wide angle position shown in FIG. 1. Between the wide angle
position and the telephoto position, reduced zoom images are formed
through an electronic processing to be described later.
[0066] An example of dimension data of the first embodiment in FIG.
1 is as follows: the outer diameter of the cylindrical section 26
of the fixed body 24 is 10.5 mm, the height of the cylindrical
section 26 is 5.5 mm, and the moving stroke of the lens-barrel 12
is approximately 0.2-1.5 mm. It is desirable for the three lenses
13, 14 and 15 to be aspherical lenses that are also resin lenses.
The minimum drive time to apply current to the first drive coil 28
and/or the second drive coil 30 to switch between the wide angle
position and the telephoto position is 5 msec.
[0067] As described above, the cylindrical section 26 and the cover
42 serve as constituent members of a frame for the fixed body 24 in
the lens driving device 1 according to the first embodiment; the
cylindrical section 26 is affixed by an adhesive to the base
section 47, on which is mounted and held the rear end member 46,
which in turn holds the filter 43 and the image capturing element
44. Consequently, according to the present embodiment, the rear end
member 46 and the base section 47 also form a part of the fixed
body 24.
[0068] The first embodiment shown in FIG. 1 is a moving magnet type
configuration, in which the drive magnet 16 is placed on the
moveable side and the drive coils 28 and 30 are placed on the fixed
side. However, the lens driving device may be a moving coil type,
in which a drive coil is placed on the movable side and drive
magnets are placed on the fixed side.
[0069] For example, a moving body 10 may comprise a drive coil and
a magnetic member that are movable along with a lens 13 in the
direction of an optical axis 11, while a fixed body 24 comprises a
first drive magnet and a second drive magnet placed in the
direction of the optical axis 11 of the lens 13 to interpose the
drive coil in between and further forms a magnetic circuit with the
drive magnet. When energization of the drive coil ceases, the
magnetic attraction between either the first drive magnet or the
second drive magnet and the magnetic member causes the moving body
to be held in a predetermined position, and the energization of the
drive coil causes the moving body 10 to move between the first
drive magnet and the second drive magnet. A flexible lead wire may
have to be used in order to energize the movable drive coil, but no
special lead wires are required since, as described earlier, a
moving stroke of approximately 0.2-1.5 mm is sufficient for lens
driving devices applied to cameras mounted on portable
equipment.
[0070] In the first embodiment shown in FIG. 1, the flow of the
magnetic flux from the drive magnet 16 to the first drive coil 28
and/or the second drive coil 30 is required only to be a
directional component in the first drive coil 28 and/or the second
drive coil 30 that is required to drive the drive magnet 16.
Consequently, the drive magnet 16 can generate the flow of the
magnetic flux either more inward than the inner diameter of the
drive coils or more outward than the outer diameter of the drive
coils.
[0071] Next, referring to FIG. 5, a system configuration of a
camera 50 that includes the lens driving device 1 according to the
first embodiment will be described.
[0072] The camera 50 comprises a zoom driver 51 that drives the
moving body 10 with the lens 13, which is the first lens group, and
realizes zoom operation; an ISP (image signal processor) 52 that
processes image signals obtained from the image capturing element
44; a storage device 53 that stores image data; a control logic
section 54; one or more memories 55 that temporarily store images;
a display unit 56 that displays optical images as well as
electronic images that have been electronically processed; and an
MPU (micro processing unit) 57 that serves as a system controller
to control the various members.
[0073] A camera module that is equivalent to the lens driving
device 1 comprises mechanical parts of the lens driving device 1
consisting of the moving body 10 including the lens 13, the image
capturing element 44, the zoom driver 51 and the ISP 52. The
control logic section 54 and the MPU 57 constitute a control
section. The image capturing element 44, the ISP 52 and the control
section constitute an image capturing module. The MPU 57 can serve
as a zoom instruction reading module for reading zoom instructions,
an operational position confirmation module for confirming the
operational position of the lens 13, and a current position
detection module for detecting the position of the lens 13.
[0074] A sensor to detect the position of the lens 13, i.e., the
position of the moving body 10, can be provided to constitute a
part of the current position detection module; alternatively,
instead of providing a special sensor, the first drive coil 28 and
the second drive coil 30 may be used as sensors. In the latter
case, the first and second drive coils 28 and 30 would constitute a
part of the current position detection module.
[0075] The control logic section 54 may be built-in inside the MPU
57. The display unit 56 comprises a display device made of liquid
crystal and a display driver to drive the display device. The
display driver may be placed on the circuit substrate 45. The
display device may be LED (light emitting diode) or EL
(ElectroLuminescent), or other display device. If a plurality of
memories 55 is provided as shown in FIG. 5, temporarily stored
images can be used to perform smoother electronic processing
(digital processing) in order to execute digital zooming or to make
a composite from a plurality of images with different resolutions,
as described later.
[0076] Next, referring to FIGS. 1 and 2, a method of assembling the
lens driving device 1 according to the first embodiment will be
described.
[0077] First, the rear end member 46, which is provided with the
image capturing element 44, the circuit substrate 45 and the filter
43, is mounted and affixed to the base section 47. In the meantime,
the first magnetic member 32 is inserted into and fixed to the
cylindrical section 26 of the body 24. Next, the first drive coil
28 is placed together with the first magnetic member 32 and fixed.
After this, the drive magnet 16 is affixed and the moving body 10,
which has the lens 13 inside, is assembled to the cylindrical
section 26.
[0078] Next, the second drive coil 30 is inserted into the
cylindrical section 26 and fixed; the second magnetic member 34 is
placed together with the second drive coil 30 and fixed. Next, the
cover 42 is mounted on the cylindrical section 26 and temporarily
fixed. In this state, the cylindrical section 26 is placed in the
base section 47, the distance between the image capturing element
44 and the lens 13 is adjusted in such a way that a proper image
can be captured when the lens 13 is in the wide angle position.
When various members are in position to attain this state, an
adhesive 48 is filled between the base section 47 and the
cylindrical section 26 to fix them together.
[0079] Next, the cover 42 is moved back and forth in the direction
of the optical axis 11 and fixed in a position with which a proper
photographing is possible when the lens 13 is in the telephoto
position. In other words, the cover 42 is moved back and forth
against the cylindrical section 26 in the direction of the optical
axis 11 in order to capture a proper telephoto image (an enlarged
image) in the telephoto position when the front end surface 20 of
the lens-barrel 12 hits the positioning protrusions 36, and the
cover 42 and the cylindrical section 26 are fixed in proper
positions with an adhesive. It is preferable for the positioning
protrusions 36 to be provided in three locations at an interval of
120 degrees.
[0080] Next, referring to FIG. 6, one example of a method for
performing a digital zooming using electronic images that have been
electronically processed (digitally processed) is described. In
this example, the magnification in the telephoto position is twice
that in the wide angle position and a digital zooming of a further
2.times. magnification from the telephoto position is performed.
For this reason, the telephoto position becomes the intermediate
position in the digital zooming according to this method.
[0081] Optical images can be captured only at two positions: the
wide angle position which is the first position and the telephoto
position which is the second position. The optical images in these
two positions are utilized to obtain enlarged zoom images that are
digitally processed. The example in FIG. 6 can be executed even if
there is only one memory 55; consequently, we will describe the
following with the assumption that the camera 50 has only one
memory 55.
[0082] The MPU 57 constantly reads zoom instructions given through
the zoom switch (not shown). When the MPU 57 detects that a zoom
instruction has been given, it reads in which position the moving
body 10 should be set in terms of the operation of the camera (step
S1). If the current position of the camera in terms of operation is
at 1.times. magnification (i.e., in the wide angle position), the
optical image to be captured is an image in the wide angle position
(i.e., the first position); if the current position of the camera
in terms of operation is at 2.times. magnification (i.e., in the
telephoto position), the optical image to be captured is an image
in the telephoto position (i.e., in the second position). For this
reason, the MPU 57 in step S2 determines whether the angle of view
should be the wide angle position. In other words, the MPU 57
determines if the lens position in terms of the camera operation is
the wide angle position according to the zoom instruction issued.
If the current position of the operation is 1.times. magnification
(the wide angle position), the answer in step S2 becomes
affirmative and the MPU 57 determines whether the current position
of the lens 13 is the wide angle position (step S3). If the answer
in step S3 is affirmative, the camera 50 captures an optical image
in the wide angle position (step S4). The optical image captured in
step S4 is stored in the memory 55.
[0083] Next, the MPU 57 activates the ISP 52, retrieves from the
memory 55 the optical image captured, digitally processes the
optical image, and performs a digital zooming (step S5). The MPU 57
forms images in frame numbers of several frames to 30 frames per
second, which appear as gradually enlarging zoom images through
electronic processing. In the electronic processing, if the optical
image is 280.times.960 pixels, or approximately 1.22 million
pixels, a 2.times. magnification reduces the pixels to
640.times.480 pixels, or approximately 300,000 pixels. Although the
number of pixels becomes approximately one-fourth of the optical
image, since the display area is the same when a 2.times.
magnification image is displayed on the display unit 56,
information on the 300,000 pixels is utilized to interpolate the
display pixels when displaying in the 2.times. magnification.
[0084] Pixel interpolation can be performed using the zero-order
hold method, in which each of the 300,000 pixels is aligned in
quadrupled regions, or the linear interpolation method, in which
new pixels for the enlargement are created through linear
approximation between adjacent pixels of the original image (i.e.,
the part comprising 300,000 pixels). However, regardless of the
interpolation method used, the image quality may be grainy when the
interpolated image is displayed on the display unit 56 (step S6),
since the original image has a fewer number of pixels to begin
with.
[0085] After the zoom image is displayed, the process returns to
step S1 following a predetermined amount of time. It is desirable
for the predetermined amount of time to be a value greater than 5
msec and a time during which panning while photographing would not
appear awkward. Specifically, 10-100 msec may be desirable, and
20-50 msec may be even more desirable. Since an optical image is
captured once again in the wide angle position after digital zoom
images are displayed in step S6, proper images are obtained in
panning photograph. In this way, enlarged zoom images that are
gradually enlarged through the digital zooming continue to be
displayed on the display unit 56.
[0086] In step S3, if the answer is negative, the MPU 57 instructs
the zoom driver 51 to move the moving body 10, i.e., the lens 13,
to the wide angle position (step S7). Subsequent to this,
processing in steps S4, S5, S6, S1, S2, S3, S4 . . . follows and
the MPU 57 continues to display enlarged zoom images through
digital zooming on the display unit 56.
[0087] If the current operational position is the telephoto
position (i.e., the intermediate position), the MPU 57 makes a
negative judgment in step S2 and proceeds to step S11. In step S11,
the MPU 57 determines whether the current position of the lens 13
is the telephoto position. If the answer is affirmative, the MPU 57
controls the image capturing element 44 and captures an optical
image in the telephoto position (step S4). After this, the MPU 57
uses the optical image in the telephoto position but otherwise
performs the processing in steps S5 and S6 as in the prior case,
and repeats steps S1, S2, S11, S4 . . . As a result, gradually
enlarging images continue to be displayed as electronic images
through digital zooming of greater than 2.times. magnification.
[0088] If the answer in step S11 is negative, the MPU 57 instructs
the zoom driver 51 to move the moving body 10, i.e. the lens 13, to
the telephoto position (step S12). Next, the MPU 57 goes through
the steps S4, S5, S6 to display an electronic image of greater than
2.times. magnification, and repeats steps S1, S2, S11, S4, S5, S6 .
. . to continue to display gradually enlarging electronic images
through digital zooming on the display unit 56.
[0089] If the zoom instruction is for a 2.times. magnification or a
magnification greater than 2.times., in addition to the optical
image in the wide angle position, an optical image in the telephoto
position is captured when the magnification of the digital zooming
reaches 2.times., and the 2.times. magnification optical image
instead of an electronic image is displayed on the display unit 56
for the 2.times. magnification display. This causes the number of
pixels immediately before the 2.times. magnification to be
one-fourth of the original number of pixels, but the number of
pixels returns to the original full number in the 2.times.
magnification, which means that the image quality is excellent.
Furthermore, since the subsequent digital zooming is made by
electronically processing the optical image captured in the
telephoto position in which the original image quality has been
restored, the deterioration of the image quality is prevented to a
large extent.
[0090] If a zoom instruction is issued when the zooming position in
terms of camera operation is at 2.times. magnification, i.e., when
the current position of the lens 13 in terms of camera operation is
indicated as the telephoto position, instead of proceeding from
step S2 to step S3, zooming begins from the telephoto position;
consequently, digital zooming is executed by repeating steps S2,
S11, (S12), S4, S5, S6, S1, S2, S11, S4 . . . The position of the
lens 13 is detected in steps S3 and S11; however, if a sensing
mechanism is not provided, the processing may be set to always
proceed to step S7 if the answer in step S2 is affirmative, and the
processing may be set to always proceed to step S12 if the answer
in step S2 is negative.
[0091] Next, with reference to FIG. 7, another method for
performing a digital zooming using electronic images that have been
electronically processed is described. This is an example of
enlargement zooming, as well as an example of reduction
zooming.
[0092] The MPU 57 reads a zoom instruction (either an enlargement
zooming or a reduction zooming) given through the zoom switch (not
shown) (step S21). Next, the MPU 57 detects whether the zoom
instruction that was read is for an enlargement zooming (step S22).
If it is for an enlargement zooming, the MPU 57 proceeds to step
S23 and determines whether the zoom instruction is within the range
of 2.times.-4.times. magnification (step S23). If the determination
made is affirmative, the MPU 57 detects whether the current
position of the lens 13 is the telephoto position (the second
position) (step S24); if the answer is affirmative, the MPU 57
proceeds to step S25 where an optical image in the telephoto
position is captured. Next, the MPU 57 proceeds to steps S26 and
S27, which are the same as the prior steps S5 and S6, and shows on
the display unit 56 a zoom image that has been enlarged through
digital zooming.
[0093] If the answer in step S24 is negative, i.e., if the lens 13
is not in the telephoto position, the MPU 57 proceeds to step S28,
where the moving body 10 is driven to the telephoto position
(2.times. magnification) side accordingly. Following this, an
optical image in the telephoto position is captured in step S25.
Next, the MPU 57 proceeds to steps S26 and S27 and shows on the
display unit 56 a zoom image that has been enlarged through digital
zooming.
[0094] If the answer in step S23 is negative, i.e., if the zoom
instruction is for 1.times.-2.times. magnification, the MPU 57
detects whether the lens 13 is in the wide angle position (step
S31). If the lens 13 is in the wide angle position, the MPU 57
proceeds to step S25, where an optical image in the wide angle
position (1.times. magnification) is captured. Next, the MPU 57
proceeds to steps S26 and S27 and shows on the display unit 56 a
zoom image that has been enlarged through digital zooming.
[0095] If in step S31 the MPU 57 determines that the lens 13 is not
in the wide angle position, the MPU 57 instructs the zoom driver 51
to move the lens 13, i.e., the moving body 10, to the wide angle
position (1.times. position). Next, the camera 50 photographs an
optical image in the wide angle position; the processing proceeds
to steps S26 and S27, and further on to steps S21, S22, S23, S31
and S25, so that gradually zooming images in 1.times.-2.times.
digital zooming continue to be displayed on the display unit
56.
[0096] If in step S22 the MPU 57 determines that the zoom
instruction is not for an enlargement zooming, i.e., if a reduction
zooming is instructed, the MPU 57 determines whether the zoom
instruction starts within the range of 2.times.-4.times.
magnification (step S41). If the answer is affirmative, the MPU 57
determines whether the position of the lens 13 is the telephoto
position (step S42). If the lens 13 is in the telephoto position,
an optical image in the telephoto position (2.times. magnification)
is captured (step S43). An enlarged image (an image in
magnification greater than 2.times. magnification) as currently
designated is created using the optical image captured in the
telephoto position, and reduced zoom images that follow are also
created using the optical image (step S44). The electronic images
created are displayed on the display unit 56 (step S45).
[0097] The enlarged image in step S44 is created through the
zero-order hold method or the linear interpolation method discussed
earlier. The reduction of images starting from the enlarged image
that is executed in step S44 uses as its initial image an enlarged
image of the optical image captured in the telephoto position. As a
result, the reduction zooming that takes place in step S44 is in
fact a gradual return to the original optical image from the
enlarged image.
[0098] In the zero-order hold method and the linear interpolation
method that are used for image enlargement, an image size is
enlarged in integer multiples. To enlarge images in non-integer
multiples, a downsampling method and an averaging operation method
are combined to reduce an image size to a fraction of an integer.
For example, if the reduction rate is {fraction (4/3)}, the image
is first magnified 4.times. then reduced to 1/3, which results in
an image that is {fraction (4/3)} of the original image size.
[0099] If the lens 13 is determined, in step S42, not to be in the
telephoto position, the MPU 57 drives the moving body 10 to move
the moving body 10 to the telephoto position side (step S46). Next,
the processing proceeds to steps S43, S44 and S45, where a reduced
zoom image is displayed on the display unit 56; the processing then
returns to S21 and goes through a similar process to display
further reducing zoom images. In this way, the MPU 57 continues to
display gradually reducing zoom images on the display unit 56. This
display continues until the magnification reaches 2.times.. When
the magnification becomes 2.times. (i.e., the magnification in the
telephoto position), the optical image that has been photographed
is read from the memory 55 and displayed on the display unit
56.
[0100] If the reduction zooming is to start at less than 2.times.
magnification, the answer in step S41 becomes negative and the MPU
57 determines whether the lens 13 is in the wide angle position
(step S51). If the answer is affirmative, an optical image is
captured in the wide angle position (step S43). Subsequently, the
processing proceeds to steps S44 and S45, where reduction zooming
from less than 2.times. to 1.times. magnification takes place.
[0101] If in step S51 the MPU 57 determines that the lens 13 is not
in the wide angle position, the MPU 57 drives the lens 13, i.e. the
moving body 10, to move the lens 13 to the wide angle position
(step S52). Subsequently, the processing proceeds to steps S43,
S44, S45, S21, S22, S41, S51, S43, S44 . . . , whereby the MPU 57
uses the optical image in the wide angle position to create reduced
zoom images and continuously displays gradually reducing zoom
images on the display unit 56.
[0102] According to the method shown in FIG. 7, when performing a
reduction zooming, an optical image at a lower magnification than
the final magnification is captured in advance and enlarged images
of the optical image are created through electronically processing
the optical image. As a result, the reduced zoom images have good
image quality, like the enlarged zoom images.
[0103] Next, another method for digital zooming will be described
with reference to FIGS. 8 through 10. According to this method,
when performing an enlargement digital zooming, a first optical
image as well as a second optical image enlarged in a different
magnification are utilized; when performing a reduction digital
zooming, in addition to the second optical image, which is an
optical image in an intermediate magnification between the initial
and final magnifications is utilized. Through this, the image
quality of both is improved. In this example, since two optical
images are used, at least two memories 55 are required in the
camera 50.
[0104] First, an enlargement zooming operation is described with
reference to FIG. 8. First, the MPU 57 sets the lens 13 to the wide
angle position (step S61). Next, the MPU 57 captures an optical
image in the wide angle position (step S62). The optical image is
stored in the memory 55a. The MPU 57 uses the optical image to
create a zoom image in digital zooming (step S63), and displays the
zoom image on the display unit 56 (step S64).
[0105] Next, the MPU 57 determines whether the digitally processed
electronic image has exceeded a predetermined threshold (a first
threshold), i.e. a predetermined magnification (step S65). In this
example, 1.7.times. magnification, i.e. a position in which the
magnification in the wide angle position and the magnification in
the telephoto position are divided 7:3, is set as the predetermined
threshold. Consequently, as long as the magnification of the
electronic image does not exceed 1.7.times., the processing returns
to step S62 to repeat photographing and to continue to display
enlarged images based on the optical image captured in the wide
angle position.
[0106] If the magnification reaches 1.7.times. in step S65, the
processing proceeds to step S66, where the MPU 57 drives the lens
13 to the telephoto position. An optical image is photographed in
the telephoto position (step S67), and the image is stored in the
memory 55b. Next, the electronic magnification increases further
and the MPU 57 determines if a predetermined threshold (a second
threshold) has been exceeded (step S68). Since the first threshold
was 1.7.times., a magnification greater than 1.7.times. will be
used as the second threshold in this example. For example,
1.8.times. will be used as the second threshold.
[0107] If the magnification does not exceed the second threshold in
step S68, the processing returns to step S62, and digital zooming
utilizing the latest optical image captured in the wide angle
position continues to take place. On the other hand, if the
magnification does exceed the second threshold in step S68, the MPU
57 utilizes the optical image captured in the telephoto position
that was stored in the memory 55b to obtain zoom images in digital
zooming (step S69). In this case, the optical image in the memory
55a may also be used in conjunction, as described later.
[0108] Next, an electronically processed image is displayed on the
display unit 56 in step S70, and the processing returns to step S67
and proceeds to steps S68, S69 and S70 to continue to display
enlarging electronic images using the latest optical image captured
in the telephoto position.
[0109] In this way, according to this example, electronic images
between 1.8.times. to 2.times. magnification are created by using
an optical image in the telephoto position (2.times. magnification
position). When an optical image in the wide angle position is
electronically processed and enlarged to nearly 2.times., the
number of pixels reduces to approximately one-fourth. This causes
the image quality to deteriorate; however, since enlarged
electronic images in 1.8.times. or greater magnification, which are
created using an optical image captured in the telephoto position,
have the same number of pixels as that of the original optical
image, the deterioration of the image quality can be prevented to a
large extent.
[0110] Due to the fact that the angle of view is narrow in the
telephoto position, when an optical image in the telephoto position
is used to create a 1.8.times. magnification image, the resulting
image lacks information on its periphery, as indicated in FIG. 9
(a). To address this issue, it is preferable to obtain a 1.8.times.
magnification electronic image by slightly reducing the optical
image captured in the telephoto position (FIGS. 9 (b)) and placing
it in the center of the display screen, while pasting on the
periphery of the display screen an image that has been enlarged
from an optical image in the wide angle position, thereby creating
a composite image, as indicated in FIG. 9 (c). Examples in FIGS. 9
and 10 describe the concept of creating an image and are not meant
to be an absolute assurance that a 1.8.times. magnification image
would actually be an image as shown in FIG. 9 or 10.
[0111] When an optical image captured in the telephoto position is
used, there is a discrepancy in the angle of view of the optical
image captured through photographing and a display region displayed
on the display unit 56. If the former is wider, only the optical
image captured in the telephoto position (FIG. 10 (b)) is used
without using the optical image captured in the wide angle position
(FIG. 10 (a)) in order to display an image with 1.8.times.
magnification or greater. In other words, if the display region is
narrower than the region of the optical image captured in each
position (as indicated in FIG. 10 (d)), the size of an image that
is slightly reduced (a 1.8.times. magnification image) from the
optical image captured in the telephoto position generally becomes
the same size as the size of the display region, so that a
1.8.times. magnification image (FIG. 10 (e)) can be obtained solely
from the optical image captured in the telephoto position.
[0112] When the magnification increases to 2.times., the MPU 57
uses the optical image captured in the telephoto position unaltered
and displays it as the 2.times. magnification image (i.e., the
image in the telephoto position) on the display unit 56. When the
magnification exceeds 2.times. magnification, the processing
repeats each of the steps S67, S68, S69, S70, S67 . . . In this
case, enlarged electronic images are created using the optical
image captured in the telephoto position. This makes it possible to
perform a digital zooming exceeding 2.times. magnification and up
to 4.times. magnification.
[0113] Through the above, an enlargement zooming from the wide
angle position (1.times. magnification) to the telephoto position
(2.times. magnification), as well as further enlargement zooming
from the telephoto position to a 4.times. image (2.times. to
4.times. magnification), can be obtained. Images between 1.times.
and 1.8.times. magnification are called first zoom images, while
images between 1.8.times. and 2.times. magnification are called
second zoom images.
[0114] The enlargement zooming concept described above can also be
applied to reduction zooming. In other words, a reduction zooming
from a magnification of over 2.times. to 2.times. magnification is
achieved by digitally processing an optical image captured in the
telephoto position. This is the same as the earlier example shown
in FIG. 7. When the magnification is less than 2.times.
magnification, only an optical image captured in the wide angle
position is used in the digital processing to perform a reduction
zooming according to the example in FIG. 7. However, for the second
zoom image region in which the magnification X is defined by
1.8<X<2.0, an optical image captured in the telephoto
position in addition to an optical image captured in the wide angle
position can be used. The image processing in this case can be
performed by using the method shown in FIGS. 9 and 10.
[0115] For the first zoom image region in which the magnification X
is defined by X.ltoreq.1.8, only the optical image captured in the
wide angle position is used to create images to be displayed. In
such electronic processing, although employing two thresholds is
desirable for enlargement zooming, employing only one threshold is
often sufficient for reduction zooming since an optical image in
the telephoto position is already captured.
[0116] Next, a lens driving device 1A in accordance with a second
embodiment of the present invention will be described with
reference to FIG. 11. The basic configuration of the lens driving
device 1A is generally the same as that of the lens driving device
1. Accordingly, like components are assigned the same reference
numbers and their description is omitted, and different features
will be primarily described below.
[0117] In the lens driving device 1A, a ring-shaped third magnetic
member 61 is placed between a first drive coil 28 and a second
drive coil 30 to make it possible to stop and hold a drive magnet
16 at a point along its movement in the direction of an optical
axis 11. In other words, this makes a three-position step drive
possible. To explain this using a specific example, in addition to
two positions of a wide angle position and a telephoto position,
there is another position at which photographing in an intermediate
magnification between the two is possible. By placing not one but a
plurality of the third magnetic members 61 in between, a drive of
four steps or more becomes possible. Furthermore, although a lens
15, which is a third lens group, is indicated as fixed and
immovable in the direction of the optical axis 11 in FIG. 11, the
lens 15 in fact is slightly movable in the direction of the optical
axis 11 due to a reason described later.
[0118] Unlike the first embodiment, a lens 13, which is a second
lens group, comprises two lenses, a subject side lens 13a and a
body side lens 13b, in the lens driving device 1A. The subject side
lens 13a is an aspherical lens that is molded with resin in a
unitary fashion with a frame section 62, and the camera body side
lens 13b is also an aspherical lens that is molded with resin in a
unitary fashion with a frame section 63. Between the lenses 13a and
13b is placed a space maintaining member (i.e., spacer member) 13c,
and even more towards the inner end than the camera body side lens
13b is fixed a position fixing member 13d to a cylindrical section
26 in order to position the lenses 13a and 13b. A cover 42 and the
cylindrical section 26 are affixed to each other with adhesive 64,
while the cylindrical section 26 and a base section 47 are affixed
with adhesive 65.
[0119] As in the first embodiment, a gap g1 is formed between the
outer circumference of a lens-barrel 12 and the inner
circumferences of the second drive coil 30 and a second magnetic
member 34, a gap g2 is formed between the outer circumference of
the drive magnet 16 and the inner circumference of the cylindrical
section 26, and a gap g3 is formed between the outer circumference
of the lens-barrel 12 and the inner circumferences of the first
drive coil 28 and a first magnetic member 32. In the lens driving
device 1A, the gaps g1, g2 and g3 have relations of g3>g2 and
g3>g1. Furthermore, it is desirable for the gaps g1 and g2 to
have a relation of g2>g1.
[0120] Also, the lens driving device 1F is disposed in portable
equipment such as a portable telephone, such that a case front
surface 67 of the portable telephone is flush or generally flush
with a surface of the cover 42. Furthermore, an image capturing
element 44 and a circuit substrate 45 are positioned between a case
rear surface 68 of the portable telephone and the lens 15. As a
result, an ample space is provided on the outer circumference part
of the lens driving device 1A, such that the lens driving device 1A
can be readily assembled into portable equipment. The case front
surface 67 and the case rear surface 68 are not shown in other
drawings but have positional relationships similar to the ones
shown in FIG. 11 in every instance.
[0121] Due to the fact that positions can be held at three points
in the lens driving device 1A according to the second embodiment,
the resulting zooming can be a so-called three-stage zooming.
Compared to the two-stage zooming with the lens driving device 1
according to the first embodiment, the deterioration of image
quality can be further prevented with the three-stage zooming.
[0122] Referring to FIGS. 12 (a) and 12 (b), how the image quality
is prevented from deteriorating in a three-stage zooming, in other
words, how the image quality in a three-stage zooming can be
improved compared to a two-stage zooming will be described. FIG. 12
(a) is a diagram indicating changes in the number of pixels in a
two-stage zooming (i.e., in the lens driving device 1 according to
the first embodiment), while FIG. 12 (b) is a diagram indicating
changes in the number of pixels in a three-stage zooming (i.e., the
lens driving device 1A according to the second embodiment). In
both, the vertical axis indicates the number of pixels displayed
and the horizontal axis indicates the focal length (which
corresponds to the angle of view). When the focal length is 3.6 mm,
where the angle of view is wide, the position is the wide angle
position in both embodiments. When the focal length is 7.2 mm,
where the angle of view is narrow, the position is the telephoto
position. In FIGS. 12 (a) and 12 (b), a digital zooming instead of
an optical zooming is performed between the two optical positions,
i.e., in the range of 3.6 mm to 7.2 mm.
[0123] Due to the fact that only a single optical image captured in
the wide angle position is used for zoom processing when using a
single focus lens (a short focus only), the number of pixels that
is initially approximately 1.22 million pixels is reduced to
one-sixteenth in a 4.times. zooming to approximately 77,000 pixels.
With the lens driving device 1 having two focal points, the number
of pixels reduces to one-fourth through a 2.times. zooming to
approximately 300,000 pixels, but returns to the original number of
pixels at the 2.times. magnification, where once again an optical
image of 1.22 million pixels is captured, as shown in FIG. 12 (a).
Since this image is used in the digital zooming of further 2.times.
magnification, the final point in the 4.times. zooming results
again in a reduction to one-fourth of the number of pixels of the
optical image. As a result, the deterioration of image quality can
be reduced to a large extent with the two-stage zooming compared to
the deterioration with a fixed focus.
[0124] In contrast to the two-stage zooming, an optical image can
be captured at an intermediate point where the focal length is 5.4
mm with the three-stage zooming. This optical image has a
1.5.times. magnification. Consequently, the number of pixels reduce
from 1.times. to 1.5.times. magnification, so that the number of
pixels at 1.5.times. magnification is approximately 690,000 pixels,
which is approximately half of the original number of pixels;
however, since an optical image is captured again at this point,
the number of pixels returns to the original 1.22 million pixels.
Subsequently, the number of pixels reduces as before up to the
magnification of 2.times. magnification, but the number of pixels
returns to the original number of pixels at the 2.times.
magnification.
[0125] Although there is a reduction in the number of pixels during
digital zooming, the reduction can be restricted to approximately
half of the number of pixels of the optical image in the range of
1.times.-3.times. magnification with the three-stage zooming.
Consequently, the resulting image quality is more than twice as
better than that of the two-stage zooming. In the range of
magnification exceeding 2.times., the image quality with the
two-stage zooming is the same as the image quality with the
three-stage zooming.
[0126] When the lens 13 is stopped in an intermediate position
between the wide angle position and the telephoto position, the
lens 15, which is the third lens group, also needs to be driven in
two stages in the direction of the optical axis 11. This is due to
the fact that movement loci 71, 72 and 73 of the lenses 13, 14 and
15, respectively, differ, and the movement locus 73 of the lens 15,
which is the third lens group, is in the same position for the wide
angle position and the telephoto position but is towards the inner
side (towards the image capturing element 44) than these two
positions in an intermediate position m, as shown in FIG. 13
(b).
[0127] As shown in FIG. 13 (b), the position of the lens 15, which
the third lens group, for the macro position (close-up position) is
the same position as for the wide angle and telephoto positions.
Consequently, in order to add a macro function to the lens driving
device 1 according to the first embodiment, the lens driving device
1A according to the second embodiment may have an additional
function to stop in the intermediate point. In this case, the lens
15 can be fixed and be immovable in the direction of the optical
axis 11.
[0128] Although the embodiments according to the present invention
described above are preferred embodiments of the present invention,
many modifications can be made without departing from the present
invention. For example, although the cylindrical lens-barrel 12 is
indicated as a lens holder, a lens holder can be provided in a
unitary fashion with a lens and made of the same resin material as
the lens, instead of providing a lens holder separate from the
lens.
[0129] Although a magnetic drive comprising magnets and coils is
preferable as a driving device, other driving device can also be
used, such as a driving device in which rotational motion is
converted into linear motion by utilizing a motor; or a driving
device in which a guide groove is provided on the inner
circumference of a motor rotor, and a guide member is provided to
insert a protrusion of a lens holder into the groove, impede the
lens holder from rotating, and allow movement only in the optical
axis direction, so that the lens holder is allowed to move in the
optical axis direction by the rotation of the rotor.
[0130] Furthermore, although the first and second drive coils 28
and 30 as a driving device are provided to surround the lens-barrel
12, which serves as a lens holder, a lens holder can be placed
instead in such a manner that it would surround a driving device.
In addition, although the drive magnets 16 is magnetized with N and
S poles in the radial direction, it may be magnetized with N and S
poles in the direction of the optical axis 11.
[0131] In addition to methods described for image enlargement and
reduction processing, a method that uses digital filters can be
employed. By combining an upsampler and a downsampler with the
digital filter, various enlargements and reductions can be made.
When storing image data in the memory 55, a compression processing
can be performed for storage. This will require a smaller capacity
for the memory 55. However, if compression is used, a decode
processing would be required.
[0132] The camera 50 may be configured like a camera 50A shown in
FIG. 14. The camera 50A places memories 55 on a camera module side
to achieve high-speed image processing by an ISP 52 and to avoid
interference with system control by an MPU 57.
[0133] When an image photographed in an optical zoom position (the
wide angle position, the telephoto position or the intermediate
position according to the above examples) is enlarged through
electronic processing, the enlargement rate or image size (i.e.,
the number of pixels) may be displayed on the display unit 56. With
such a configuration, a user of the portable equipment would be
able to ascertain image information when photographing, which would
further enhance the ability to capture proper images. To display
the enlargement rate in such a display, for example, an optical
image can be assigned the number "0" and various degrees of image
quality deterioration can be displayed in negative values, thereby
indicating that the image quality obtained at "0" is the best image
quality.
[0134] As an application of the two-stage zooming or three-stage
zooming described above, if a display unit mounted on portable
equipment has lower resolution than the resolution of images
photographed by the lens driving device 1 or 1A, images can be
displayed on the display unit in a resolution level similar to that
of the display unit, while images can be image-processed in high
resolution only when a shutter is pressed. In other words, when the
shutter is not pressed, all images displayed on the display unit
are electronic images that have been electronically processed, i.e.
images with inferior image quality, and an optical image is
captured only when necessary, i.e., only when the shutter is
pressed, so that an image with improved image quality is captured
by the image capturing element 44 and displayed on the display
unit. This would make it possible to use relatively low speed MPU
or CPU (central processing unit) and to achieve low power
consumption.
[0135] Furthermore, zooming in four stages or more is also
possible. The total magnification or special digital zooming
ranges, such as according to the present invention, can be values
that are different from the values indicated in the embodiments. In
a three-stage or greater zooming, the final stage zooming can be
set to normal digital zooming only, but an optical image can be set
for capture in the final position of the final stage zooming
without performing any further digital zooming. Normal continuous
optical zooming can be performed up to a predetermined
magnification or within a predetermined range of magnifications, so
that a zooming in which an optical image is added to digital
zooming according to the present invention can be performed in
other ranges; furthermore, in addition to an optical zooming and
zooming according to the present invention, a pure digital zooming
(a zooming that exceeds 2.times. magnification shown in the
embodiments) can be added to create a lens driving device having
three different types of zooming.
[0136] The present invention can be applied to camera devices. It
can also be applied to other portable equipment such as portable
telephones with camera function. Furthermore, the present invention
can be assembled in any electronic equipment that has a lens
zooming mechanism.
[0137] While the description above refers to particular embodiments
of the present invention, it will be understood that many
modifications may be made without departing from the spirit
thereof. The accompanying claims are intended to cover such
modifications as would fall within the true scope and spirit of the
present invention.
[0138] The presently disclosed embodiments are therefore to be
considered in all respects as illustrative and not restrictive, the
scope of the invention being indicated by the appended claims,
rather than the foregoing description, and all changes which come
within the meaning and range of equivalency of the claims are
therefore intended to be embraced therein.
* * * * *