U.S. patent number RE39,410 [Application Number 09/692,107] was granted by the patent office on 2006-11-28 for white balance adjusting device for a camera.
This patent grant is currently assigned to Fuji Photo Film Co., Ltd.. Invention is credited to Kiyotaka Kaneko, Izumi Miyake, Yoshio Nakane, Kazuya Oda, Hiroshi Shimaya.
United States Patent |
RE39,410 |
Kaneko , et al. |
November 28, 2006 |
White balance adjusting device for a camera
Abstract
A white balance adjusting device for use in a camera which
photographs a field and forms a video signal representing the
field. In the white balance adjusting device, while a sequential
photographing is under way, updating of the color temperature data
to be used for adjusting a white balance is prohibited. Therefore,
the hues of main objects in the respective frames of still images
photographed by the sequential photographic operation remain
unchanged, thereby maintaining the homogeneity of the main objects.
Also, in the white balance adjusting device, control a device is
used to provide a short response time for a quick response property
in a still mode and to provide a longer response time in a movie
mode when compared with the still mode. As a result, the white
balance can be adjusted according to the photographic modes of the
camera.
Inventors: |
Kaneko; Kiyotaka (Tokyo,
JP), Miyake; Izumi (Tokyo, JP), Oda;
Kazuya (Tokyo, JP), Nakane; Yoshio (Tokyo,
JP), Shimaya; Hiroshi (Tokyo, JP) |
Assignee: |
Fuji Photo Film Co., Ltd.
(Kanagawa, JP)
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Family
ID: |
26520293 |
Appl.
No.: |
09/692,107 |
Filed: |
October 20, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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07236992 |
Aug 26, 1988 |
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Reissue of: |
07366210 |
Jun 15, 1989 |
04899212 |
Feb 6, 1990 |
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Foreign Application Priority Data
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Aug 28, 1987 [JP] |
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62-214382 |
Aug 28, 1987 [JP] |
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62-214383 |
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Current U.S.
Class: |
348/223.1;
348/227.1; 348/220.1 |
Current CPC
Class: |
H04N
9/735 (20130101); F02B 2075/025 (20130101) |
Current International
Class: |
H04N
9/73 (20060101); H04N 5/225 (20060101) |
Field of
Search: |
;348/220,223,224,225,227,226,228,655,225.1,226.1,227.1,207.99,220.1,222.1,223.1,224.1,228.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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55-30265 |
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Mar 1980 |
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JP |
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56-4993 |
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Jan 1981 |
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JP |
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60-254980 |
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Dec 1985 |
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JP |
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61-240790 |
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Oct 1986 |
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JP |
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Other References
"Video Movies", by Tony Galluzo, Modern Photography, Dec. 1981
(Galluzo Publication). cited by other .
Definitions of "adjust" and "set" from ROGETS' II The New
Thesaurus, 1980. cited by other .
Definition of "sequence" from Webster's Third New International
Dictionary. cited by other .
Definition of "field" from the IEEE Standard Dictionary of
Electrical and Electronics Terms, Fourth Edition, 1988. cited by
other .
"Cine Camera", by George H. Sewell and Julien Caunter, pp. 199-212
of The Focal Encylopedia of Photogrphay, 1969 (Cine Article). cited
by other .
Definitions of "cinematograph", and "cinematography" from Webster's
Ninth New Collegiate Dictionary, 1985. cited by other.
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Primary Examiner: Ometz; David
Assistant Examiner: Nguyen; Luong T.
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Parent Case Text
This application is a continuation of application Ser. No. 236,992,
filed on Aug. 26, 1988.
Claims
What is claimed is:
.[.1. A white balance adjusting device for use in a camera having
at least a single photographic mode in which, when a shutter
release operation is performed, an image of a field is picked up by
a single frame and a video signal representing the still image
thereof is formed and a sequential photographic mode in which,
while said shutter release operation is being performed, the images
of said field are picked up sequentially for every predetermined
period of time and video signals respectively representing the
still images thereof are formed, said white balance adjusting
device comprising: single/sequential photographic mode setting mode
setting means for setting said single photographic mode and said
sequential photographic mode; operation means for performing said
shutter release operation; color temperature detecting means for
detecting a color temperature of said field and outputting a color
temperature signal representing said color temperature; and control
means for adjusting a white balance of said video signal in
response to color temperature data that is obtained from said color
temperature signal, said control means receiving a set output from
said single/sequential photographic mode setting means and an
output signal from said operation means and prohibiting said color
temperature data that is used for adjusting said white balance from
being updated when a sequential photographic operation is being
performed..].
.[.2. A white balance adjusting device for use in a camera as set
forth in claim 1, wherein said color temperature detecting means
comprises: a color temperature detection element for outputting a
first photocurrent signal corresponding to an R component of an
incident light from said field and a second photocurrent signal
corresponding to a B component of said incident light; a
logarithmic conversion circuit for receiving a detection output
from said color temperature detection element, compressing said
detection output logarithmically and outputting an R signal and a B
signal respectively corresponding to said R and B components of
said incident light; a subtraction circuit for calculating a
difference between said R and B signals output from said
logarithmic conversion circuit; and an amplifier for amplifying a
subtraction output signal from said subtraction circuit up to a
predetermined level..].
.[.3. A white balance adjusting device for use in a camera as set
forth in claim 2, wherein said color temperature detection element
comprises a first photo diode for receiving only said R component
of said incident light from said field and a second photo diode for
receiving only said B component of said incident light, wherein
said first and second photo diodes are connected in series to each
other in such a manner that the respective cathodes thereof are
directly connected to each other for allowing said first and second
photo diodes to have mutually opposite polarities..].
4. A white balance adjusting device for use in a camera in which a
field is photographed and a video signal representing said field is
formed, said device comprising: photographic mode setting means for
setting a still mode for photographing said field as a still image
and a movie mode for photographing said field as a moving image;
color temperature detecting means for detecting a color temperature
of said field and outputting a color temperature signal
representing said color temperature; and control means for
adjusting a white balance of said video signal in response to color
temperature data that is obtained from said color temperature
signal, said control means receiving a set output from said
photographic mode setting means and adjusting said white balance of
said video signal at a shorter cycle as compared with said movie
mode when said camera is set in said still mode.Iadd.; wherein when
the still mode is set by the photographic mode setting means, the
control means obtains the color temperature signal used for the
white balance adjustment so that a first response time length
between the detection of the color temperature by the color
temperature detecting means and the white balance adjustment for
the image signal of the still image is at most a predetermined time
length; wherein when the movie mode is set by the photographic mode
setting means, the control means obtains the color temperature
signal from the color temperature detecting means so as to adjust
the white balance of the image signal composing the moving image if
the color temperature of the field varies while the photographing
of the moving image is continuously performed in the movie mode,
and the control means obtains the color temperature signal used for
the white balance adjustment so that a second response time length
between the detection of the color temperature by the color
temperature detecting means and the white balance adjustment for
the image signal of each of frames composing the moving image is
longer than the predetermined time length and is longer than a
photographing cycle of the frames composing the moving
image.Iaddend..
5. A white balance adjusting device for use in a camera as set
forth in claim 4, wherein said color temperature detecting means
comprises: a color temperature detection element for outputting a
first photocurrent signal corresponding to an R component of an
incident light from said field and a second photo current signal
corresponding to a B component of said incident light; a
logarithmic conversion circuit for receiving a detection output
from said color temperature detection element, compressing said
detection output logarithmically and outputting an R signal and a B
signal respectively corresponding to said R and B components of
said incident light; a subtraction circuit for calculating a
difference between said R and B signals output from said
logarithmic conversion circuit; and an amplifier for amplifying a
subtraction output signal of said subtraction circuit up to a
predetermined level.
6. A white balance adjusting device for use in a camera as set
forth in claim 5, wherein said color temperature detection element
comprises a first photo diode for receiving only said R component
of said incident light from said field and a second photo diode for
receiving only said B component of said incident light, wherein
said first and second photo diodes are connected in series to each
other in such a manner that the respective cathodes thereof are
directly connected to each other for allowing said first and second
photo diodes to have mutually opposite polarities.
.Iadd.7. The white balance adjusting device for use in the camera
as defined in claim 4, wherein: the color temperature detecting
means sequentially detects color temperatures of the field at a
predetermined cycle and sequentially outputs first color
temperature signals representing the detected color temperatures;
and when the movie mode is set by the photographic mode setting
means, the control means sequentially compares each of the first
color temperature signals sequentially outputted from the color
temperature detecting means with a second color temperature signal
currently used for the white balance adjustment, and if color
temperature change conditions in which a difference between the
each of the first color temperature signals and the second color
temperature signal is at least a constant value occur a first
number of times, then the control means obtains a latest first
color temperature signal and updates the second color temperature
signal used for the white balance adjustment by the latest first
color temperature signal..Iaddend.
.Iadd.8. The white balance adjusting device for use in the camera
as defined in claim 7, wherein when the movie mode is set by the
photographic mode setting means, the control means sequentially
compares each of the first color temperature signals sequentially
outputted from the color temperature detecting means with the
second color temperature signal currently used for the white
balance adjustment, and if color temperature changing conditions in
which symbols of the differences between the first color
temperature signals and the second color temperature signal are the
same and absolute values of the differences are at least the
constant value occur sequentially the first number of times, then
the control means obtains the latest first color temperature signal
and updates the second color temperature signal used for the white
balance adjustment by the latest first color temperature
signal..Iaddend.
.Iadd.9. The white balance adjusting device for use in the camera
as defined in claim 4, wherein when the still mode is set by the
photographic mode setting means, the control means compares a first
color temperature signal outputted from the color temperature
detecting means with a second color temperature signal currently
used for the white balance adjustment, and if a color temperature
change condition in which a difference between the first color
temperature signal and the second color temperature signal is at
least a constant value occurs, then the control means obtains a
latest first color temperature signal and updates the second color
temperature signal used for the white balance adjustment by the
latest first color temperature signal..Iaddend.
.Iadd.10. The white balance adjusting device for use in the camera
as defined in claim 7, wherein when the still mode is set by the
photographic mode setting means, the control means sequentially
compares each of the first color temperature signals sequentially
outputted from the color temperature detecting means with the
second color temperature signal currently used for the white
balance adjustment, and if color temperature change conditions in
which a difference between the each of the first color temperature
signals and the second color temperature signal is at least a
constant value occur a second number of times, the second number
being less than the first number, then the control means obtains a
latest first color temperature signal and updates the second color
temperature signal used for the white balance adjustment by the
latest first color temperature signal..Iaddend.
.Iadd.11. The white balance adjusting device for use in the camera
as defined in claim 8, wherein when the still mode is set by the
photographic mode setting means, the control means sequentially
compares each of the first color temperature signals sequentially
outputted from the color temperature detecting means with the
second color temperature signal currently used for the white
balance adjustment, and if color temperature changing conditions in
which symbols of the difference between the first color temperature
signal and the second color temperature signal are the same and
absolute values of the differences between the first color
temperature signal and second color temperature signal are at least
the constant value occur sequentially a second number of times, the
second number being less than the first number, then the control
means obtains the latest first color temperature signal and updates
the second color temperature signal used for the white balance
adjustment by the latest first color temperature
signal..Iaddend.
.Iadd.12. The white balance adjusting device for use in the camera
as defined in claim 4, wherein: the still mode which is set by the
photographic mode setting means includes a single mode for
photographing the field by a single frame and a sequential mode for
sequentially photographing the field at constant intervals; and
when the sequential mode is set by the photographic mode setting
means, the control means prohibits updating the color temperature
signal that is used for the white balance adjustment at a
photographing of a first frame during the sequential photographing
after the first frame..Iaddend.
.Iadd.13. A white balance adjusting system for a camera,
comprising: a mode setting device configured to set the camera in
one of a still mode and a movie mode, wherein in the still mode a
field is photographed as one or more still images and wherein in
the movie mode, the field is photographed as a continuously moving
image; a color temperature detecting device configured to detect a
color temperature of the field; and a controlling device
operatively connected to the mode setting device and the color
temperature detecting device, wherein the controlling device is
configured to adjust white balance of a video signal in response to
the color temperature detected by the color temperature device,
wherein in the movie mode, the controlling device initially sets
and periodically updates the white balance of the video signal of
the continuously moving image and wherein a length of time between
updates is longer than a photographing cycle of frames composing
the moving image..Iaddend.
.Iadd.14. The white balance adjusting system of claim 13, wherein
the still mode includes a single mode and a sequential mode,
wherein the field is photographed in a single frame in the single
mode and the field is sequentially photographed in corresponding
frames at constant intervals, and wherein the controlling device
initially sets but prevents further updates to the white balance of
the video signal when in sequential mode..Iaddend.
.Iadd.15. The white balance adjusting system of claim 13, wherein
in the movie mode, the controlling device is configured to update
the white balance of the video signal if a difference between a
previous color temperature corresponding to a white balance prior
to the update and a current color temperature is greater than a
preset value..Iaddend.
.Iadd.16. A method to adjust white balance for a camera, the method
comprising: setting the camera in one of a still mode and a movie
mode according to a selection from a user, wherein in the still
mode a field is photographed as one or more still images and
wherein in the movie mode, the field is photographed as a
continuously moving image; detecting an initial color temperature
of the field; and initially setting a white balance of a video
signal in response to the detected initial color temperature; and
periodically updating the white balance of the video signal of the
continuously moving image if the camera is in the movie mode,
wherein a length of time between updates is longer than a
photographing cycle of frames composing the moving
image..Iaddend.
.Iadd.17. The method of claim 16, wherein the still mode includes a
single mode and a sequential mode, wherein the field is
photographed in a single frame in the single mode and the field is
sequentially photographed in corresponding frames at constant
intervals, the method further comprising preventing further updates
to the white balance of the video signal when the camera is in the
sequential mode..Iaddend.
.Iadd.18. The method of claim 16, wherein the periodically updating
step comprises: detecting a current color temperature of the field;
and updating the white balance of the video signal if a difference
between a previous color temperature corresponding to the white
balance prior to the update and the current color temperature is
greater than a preset value..Iaddend.
.Iadd.19. The method of claim 16, wherein the periodically updating
step comprises: sequentially detecting color temperatures of the
field at predetermined cycles; and updating the white balance of
the video signal if: a direction of a color change is same for a
predetermined consecutive cycles, and an amount of color
temperature change between each of the consecutive cycles is equal
to or greater than a predetermined value..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a white balance adjusting device
for use in a camera in which the image of a field to be
photographed is picked up and then a video signal representing the
field is created.
2. Description of the Related Art
Recently, there has been developed an attractive electronic still
camera system wherein an image pickup device, such as a solid image
pickup element, an image pickup tube or the like, is combined with
a recording device employing, as a recording medium, an inexpensive
magnetic disc having a comparatively higher memory capacity for
photographing an object electronically recording the object into
the rotating magnetic disc and reproducing an image by a television
system or a printer separately provided.
In the above-mentioned electronic still cameras, there is included
an electronic still camera which is provided with a photographic
mode including a still mode wherein an image of a field is picked
up and is then recorded as a still image and a movie mode wherein
the camera can photograph a field as a movie camera by connecting a
video adapter to the camera. In this type of electronic still
camera, to record a color image, the white balance of the camera
must be adjusted in accordance with the kinds of illumination
lights in photographing, according to or regardless of whether the
photographic mode is the still mode or movie mode.
Because a color camera cannot adapt itself to colors like human
eyes do, the color camera must be adjusted such that even in a
television receiver the black and white colors of the field can be
seen as black and white as they actually are. For this reason, in
order to make the color separation components of a video signal
obtained from an image pickup device uniform according to the color
temperatures of the illumination lights, the camera white balance
adjustment is performed to thereby adjust the amplification gains
thereof.
In general, a movie camera (video camera) is set to have a property
of a comparatively slow response from the input of the color
temperature data of the field by the color temperature detection
device thereof to the execution of the white balance adjustment.
This slow response results because the color temperatures in the
natural world vary in a wide range of time but the variations
thereof are normally slow.
In other words, in the movie camera, because great importance is
placed on the correlation (continuity) of the screen thereof, the
response property for the white balance adjustment is set slow.
On the other hand, when the electronic still camera is set in the
still mode for photographing, a shutter chance occurs in an instant
and thus the white balance adjustment must be carried out in
accordance with the color temperature of the field in that instant.
For example, such a case may occur in which, after the camera is
directed toward a room, the camera is directed in an instant
outside of the room for photographing.
By the way, the still mode of the electronic still camera includes
a single photographic mode and a sequential photographic mode. The
single photographic mode is a basic operation mode in which when a
shutter release is executed, the image of the field is picked up by
a frame and a video signal representing the still image thereof is
recorded.
On the other hand, the sequential photographic mode is an operation
mode in which, while the shutter release is being executed, the
image of the field is picked up sequentially every given period of
the time and a video signal representing the still image thereof is
recorded.
In the single photographic mode, as discussed above, the white
balance adjustment must be made in compliance with the color
temperature of the field in the instant of the shutter release, but
this cannot apply to the sequential photographic mode. That is, due
to the fact that the reflected light of the field (object) is
detected by a color temperature sensor and the white balance
adjustment is made by a control part according to the detected
output of the sensor, when the sequential photographic mode is used
to photograph, for example, a moving object, if the background of
the object is varying in succession, then the white balance
adjustment must be made according to the variations of the color
temperature of the varying background.
As a result of this, the image of the object is tinged with the
color of the background, which damages the homogeneity (which means
that the object is photographed substantially in the same color
hue) of the same main object in a plurality of still images picked
up by means of the sequential photographic mode.
In the sequential photographic mode, as in the movie mode, due to
the high correlation between a series of images photographed, the
homogeneity of the main object is required.
SUMMARY OF THE INVENTION
The present invention aims at eliminating the drawbacks found in
the above-mentioned conventional devices.
Accordingly, it is a first object of the invention to provide a
camera white balance adjusting device which is capable of
maintaining the homogeneity of a main object regardless of the
variations of the color temperature of a field when photographing a
still image by means of a sequential photographic mode.
It is a second object of the invention to provide a camera white
balance adjusting device which is capable of changing properly the
response property of a camera from the detection of the color
temperature of a field up to the execution of a white balance
adjustment.
In order to achieve the first object, according to one aspect of
the invention, there is provided a white balance adjusting device
for use in a camera which includes at least a single photographic
mode in which, when a shutter release operation is performed, an
image of a field is picked up by a single frame and a video signal
representing the still image thereof is formed and a sequential
photographic mode in which, while the shutter release operation is
being performed, the images of the field are picked up sequentially
at every given time and video signals respectively representing the
still images thereof are formed. The white balance adjusting device
includes a single/sequential photographic modes setting device for
setting the photographic mode of the camera to either the single
photographic mode or the sequential photographic mode, an operation
device for performing the shutter release operation, a color
temperature detecting device for detecting the color temperature of
the field and outputting a color temperature signal representing
the detected color temperature, and a control device for adjusting
the white balance of the video signal(s) in accordance with the
color temperature data that are obtained from the color temperature
signal. The control device takes the set output of the
single/sequential photographic mode setting device and the output
signal of the operation device and, while a sequential photographic
operation is being performed, prohibits updating of the color
temperature data that is used for the white balance adjustment.
In the white balance adjusting device for use in a camera according
to the invention, a state wherein the photographic mode is set in
the still mode operate the single/sequential photographic mode
setting device to set up the sequential photographic mode.
When the sequential photographic mode is set and the shutter
release operation is performed by the operation device, then the
sequential photographic operation is executed.
While the sequential-photographic operation is being performed, the
control device prohibits updating of the color temperature data to
be used for the white balance adjustment.
As mentioned above, according to the invention, since the updating
of the color temperature data is prohibited during the sequential
photographic operation, the color hue of the main object in the
respective framewise still images photographed by means of the
sequential photographic operation remains unchanged, so that the
homogeneity of the main object can be maintained.
Further, in attaining the second object, according to another
aspect of the invention, there is provided a white balance
adjusting device for use in a camera in which a field is
photographed and a video signal representing the field is formed.
The device includes a photographic mode setting device for setting
either a still mode for photographing the field as a still image or
a movie mode for photographing the field as a moving image, a color
temperature detecting device for detecting the color temperature of
the field and outputting a color temperature signal representing
the color temperature, and a control device for adjusting the white
balance of the video signal in accordance with the color
temperature data that is obtained from the color temperature
signal. The control device takes the set output of the photographic
mode setting device and, when the photographic mode is set in the
still mode, adjusts the white balance of the video signal at a
shorter cycle when compared with the movie mode.
In the white balance adjusting device for use in a camera according
to the invention, the still mode or the movie mode is set by means
of the photographic mode setting device. When the photographic mode
is set in the still mode for photographing the field as a still
image, to provide a quick response, a response time required from
the detection of the color temperature of the field up to the
execution of the white balance adjustment is controlled to a short
amount of time by the control device. In the movie mode, to be able
to provide a response property similar to a conventional movie
camera, the abovementioned response time is controlled by the
control device such that the time is longer than the time in the
still mode.
Thus, according to the invention, the white balance adjustment
suitable for the photographic mode can be realized.
BRIEF DESCRIPTION OF THE DRAWINGS
The exact nature of this invention, as well as other objects and
advantages thereof, will be readily apparent from consideration of
the following specification relating to the accompanying drawings,
in which like reference characters designate the same or similar
parts throughout the figures thereof and wherein:
FIG. 1 is a block diagram of the structure of an embodiment of a
white balance adjusting device for use in an electronic still
camera according to the invention;
FIG. 2 is a flow chart of the contents of a program to be executed
by a control part shown in FIG. 1;
FIG. 3 is a timing chart used to explain a state in which a color
temperature data D.sub.O is updated; and,
FIG. 4 is a block diagram of the structure of the main portions of
a second embodiment of a white balance adjusting device according
to the invention.
DETAILED DESCRIPTION OF THE INVENTION
A detailed description will hereunder be given for the preferred
embodiments of a white balance adjusting device according to the
present invention with reference to the accompanying drawings.
Referring first to FIG. 1, there is shown a block diagram of the
structure of an embodiment of a white balance adjusting device for
use in an electronic still camera according to the invention. In
FIG. 1, the white balance adjusting device is mainly composed of an
image pickup part 10, amplifiers 22R, 22G and 22B which
respectively amplify the separation color signals 20R, 20G and 20B
of three primary colors output from the image pickup part 10, an
output part 12, a control part 16, a synchronization signal
generation part 30, a mode select switch 32 for selecting either a
single photographic mode or a sequential photographic mode, a color
temperature detection part 34, and an A/D converter 56, and a mode
setting switch 60 for setting a photographic mode.
The image pickup part 10 has an image pickup mechanism including a
color solid image pickup device such as a CCD and the like. The
image of an object is focused on the image pickup cell array of the
image pickup device by an image pickup lens 14, and the image
pickup device creates a video signal corresponding to the image of
the object.
The image pickup part 10 receives a drive clock from the control
part 16 through a control line 18. In response to the drive clock
the signals that are separated into three primary color components
R, G and B are outputted to the amplifiers 22R, 22G and 22B,
respectively.
Also, the image pickup part 10 has a shutter and a diaphragm which
are used to limit the exposure to the image pickup device. These
operations are controlled by the control part 16 through the
control line 18.
The amplifiers 22R, 22G and 22B are variable gain amplifiers
arranged such that the amplification gains thereof can be adjusted
by the control signals 24R, 24G and 24B that are output from the
control part 16, respectively.
The mode setting switch 60 is a switch which is used to set the
photographic mode of the camera into either a still mode in which a
field is photographed as a still image or a movie mode in which the
camera is used as a movie camera to photograph a field as a moving
image. When this switch is turned on, the photographic mode is set
into the movie mode, and, when the switch is turned off, the
photographic mode is set into the still mode. The output part 12,
in particular, is composed of an output terminal which is used to
output externally of the device the video signals that are output
from the amplifiers 22R, 22G and 22B, a recording section to record
the video signal as a still image into a magnetic disc, and a
switching circuit which is controlled by a control signal 28 output
from the control part 16 to switch the video signals output from
the amplifiers 22R, 22G and 22B to the output terminal side thereof
or the still image recording section side thereof according to the
photographic mode. The above-mentioned output terminal is arranged
such that a movie adapter serving as a recording part in which a
video signal recorded into a video tape can be connected to the
terminal in order that the electronic still camera can be operated
as a movie camera when the photographic mode is set into the movie
camera.
The control part 16 is composed of a microcomputer and the like and
is a control circuit which, responsive to a vertical
synchronization signal VD supplied from the synchronization signal
generation part 30 to a control line 32, controls the respective
parts of the present white balance adjusting device. For example,
it controls the exposure of the image pickup part 10 responsive to
a photographic instruction by an operator, or controls the
recording and outputting operations of the output part 12. Also,
the control part 16 performs various kinds of controls in
photographing such as a focusing control, an exposure adjustment, a
white balance adjustment and the like.
The color temperature detection part 34 is a circuit which detects
the color temperature of the field and outputs a color temperature
signal corresponding to the detected color temperature. In the
illustrated embodiment, the color temperature signal 36 is output
through the A/D converter 56 to the control part 16.
The color temperature detection part 34 includes a color
temperature detection element 38 which receives an incident light
40 from the field to which the image pickup lens 14 is directed,
and also causes a photocurrent to change responsive to the incident
light. In the incident light side of the temperature detection part
34, there are arranged an optical filter 42R which will transmit
the red (R) component of the incident light 40, and an optical
filter 42B which will transmit the blue (B) component of the
incident light.
The color temperature detection element 38 includes a pair of photo
diodes 38R and 38B which are connected in series to each other at
their mutually reversed polarities, and the respective electrodes
thereof are connected to a logarithmic conversion circuit 44. The
photo diodes 38R and 38B are disposed to correspond to the optical
filters 42A and 42B, respectively. The logarithmic conversion
circuit 44 is a circuit which operates the values of electric
currents flowing through the photo diodes 38R and 38B in a
logarithmic compression manner responsive to the photocurrents of
the photo diodes 38R and 38B. From the output terminal of the
logarithmic conversion circuit 44, a signal R corresponding to the
R component of the incident light 40 and a signal B corresponding
to the B component of the incident light 40 are output to a
subtraction circuit 48. The subtraction circuit 48 is an operation
circuit which operates a difference between both signals R and B
and outputs to an amplifier 52 a direct current level signal
corresponding to the difference and polarity.
A release button designated by 26, can be operated in a two stroke
manner. That is, when the release button 26 is operated in the
first stroke thereof, a switch SW1 is closed to thereby supply
electric power to the respective circuit parts of the device, and
when the release button 26 is further pushed into its second
stroke, a switch SW2 is closed. At the time when the switch SW2 is
closed, the control part 16 operates such that the shutter release,
photographing, and recording operations are executed.
The mode select switch 32 is a switch which selects either the
single photographic mode in which, when the shutter release
operation is executed, the field is photographed by one frame and
the video signal representing the still image thereof is recorded
into a recording medium, or the sequential photographic mode in
which, while the shutter release operation is being executed, the
field is photographed sequentially every given time and the video
signals representing the still images thereof are recorded into a
recording medium. In the sequential photographic mode, during a
period in which the switch SW2 of the release button 26 is on, the
photographing and recording of the field are performed every given
time (for example, 1/6 sec., 1/10 sec.).
The sequential photographic operation is executed when the mode
select switch 32 is set to the sequential photographic mode (the on
state thereof) and the release button 26 is depressed to thereby
turn on the switch SW2.
In addition, actually, there is provided a setting switch for
setting a sequential photographic speed (which is represented by
the number of frames per second), but a detailed description
thereof is omitted here.
In the above-mentioned structure, there is produced a difference
between the photocurrents of the photo diodes 38R and 38B according
to the ratio of the R component of the incident light 40 to the B
component thereof, and the difference is input to the logarithmic
conversion circuit 44 as an electric current signal. This electric
current signal is logarithmically compressed in the logarithmic
conversion circuit 44 and is then input to the subtraction circuit
48. In the subtraction circuit 48, a difference between the two
component signals R and B is operated, and a signal representing
this difference is amplified in the amplifier 52 and is then output
therefrom in the form of a direct current level signal. This output
signal, in particular, is output as a direct current level signal
having positive and negative signs which correspond to the
magnitude of the difference between the R and B components and the
polarities thereof. Upon receiving a clock signal 58 from the
synchronization signal generation part 30, the A/D converter 56
converts the direct current level signal into the digital data that
corresponds to the direct current level signal, and then outputs
the digital data to the control part 16.
Then, the control part 16 executes the processing to be discussed
later, inputs therein the data that represents the difference
between the R component light and the B component light. That is,
color temperature data from the A/D converter 56 in synchronization
with the vertical synchronization signal VD that is output from the
synchronization signal generation part 30, and the color
temperature data is analyzed so as to decide the color temperature
of the incident light 40. In accordance with the decision results,
the control part 16 adjusts the gains of the variable gain
amplifiers 22R and 22B, or, according to circumstances, the gain of
the variable gain amplifier 22G, so that, with respect to the white
light that enters the image pickup part 10 through the image pickup
lens 14, the levels of the video signals that are output from the
three amplifiers 22R, 22G and 22B to the output part 12 are
relatively and substantially equal to one another. As a result, in
the present device, the white balance of the video signals that are
obtained in the output part 12 can be adjusted properly.
Next, a description will be given below of the contents of the
color temperature data taking-in routine to be executed by the
control part 16 with reference to the flow chart in FIG. 2 and the
timing chart in FIG. 3. In these figures, if the switch SW1, which
serves as a power switch, of the release button 26 is turned on at
a time t.sub.1 (FIG. 3(a)), then the program is initiated, whereby
an initialization is executed in Step 100.
Here, a reference character F stands for the count value of a soft
counter which counts the number of processings of this routine.
D.sub.O represents the color temperature data that is used for the
white balance adjustment; and, L represents a flag indicating the
previous state of a flag K. The above-mentioned flag K is a flag
which is set or reset in accordance with whether a difference
D.sub.X between the color temperature data D.sub.O and the color
temperature data D.sub.T that is input from the A/D converter 56 is
beyond a given range or not.
In the still mode in which a time required from application of
power of a camera to a state thereof prepared for photography is
very short, it is necessary to shorten a response time required
from the taking-in of the color temperature data up to the start of
processing the signal for the white balance adjustment. Therefore,
in order to be able to establish the color temperature data D.sub.O
to be used for the white balance adjustment by processing the
routine only one time, in the initialization, F=2, D.sub.O=OK, L=0
are set, respectively. Although the color temperature data D.sub.O
(in common with D.sub.T) is actually not given in the unit of "K",
the above-mentioned expression is employed here for convenience of
explanation.
Now, after execution of the initialization, in Step 101 whether or
not the vertical synchronization signal VD is input from the
synchronization signal generation part 30 to the control part 16 is
checked. If the signal is not input yet, the program waits until
the vertical synchronization signal VD is input, and the program
goes to Step 102 at the time (a time t.sub.1 (FIG. 3(b)) when the
vertical synchronization signal VD is input.
In Step 102, the color temperature data D.sub.T is taken in by the
A/D converter 56 in synchronization with the vertical
synchronization signal VD (at the time t.sub.1).
By means of processing in Steps 103.about.109, whether or not the
difference D.sub.X(=D.sub.O-D.sub.T) between the color temperature
data D.sub.O and the color temperature data D.sub.T that is taken
in Step 102 has changed in the same direction with the lapse of
time is checked.
In particular, at first, in Step 103, whether or not D.sub.X=X is
checked. Here, X is set to a proper value (in the illustrated
embodiment, X=100K), so that the color temperature data D.sub.O is
to be updated only when the color temperature of the field is
clearly changed but the color temperature data D.sub.O is not to be
updated for the slight change of the field color temperature.
Since D.sub.O=OK is already set, in Step 103 D.sub.X=-D.sub.T is
obtained, and, due to the fact that the color temperature of the
illumination light of the field in photographing is at least
2,000.about.3,000K, then D.sub.X.ltoreq.-X is obtained. Therefore,
in this case, in Step 106 the flag k is reset, and then in Step 107
whether or not K=L is checked. Since L=0 is set in the
initialization, then K=L=0 is obtained. Accordingly, the content of
the flag K is considered as the content of the flag L, that is, L=0
is decided and the content of the counter F is incremented by 1
(Steps 108, 110).
Since the content of the counter F is set as F=2 in the
initialization, as a result of the incrementation thereof in Step
110, F=3 is obtained.
In Step 112, it is checked whether the photographic mode that is
set in accordance with the set output of the mode setting switch 60
is in the still mode or in the movie mode. If it is decided to be
the still mode, then whether or not the mode is set during the
sequential photographing is checked. If the mode is decided to be
set during the sequential photographing, then the program advances
to Step 115 after the counter F is reset. If the mode is not set
during the sequential photographing, the program goes directly to
Step 115 (Step 113, 114).
Whether or not the still mode is set during the sequential
photographing is checked by whether the switch SW2 of the shutter
release button 26 is on and the sequential photographic mode switch
32 is on.
The reason why the counter F is reset in the above-mentioned manner
when the still mode is during the sequential photographic mode is
because in the sequential photographic mode the photographs that
are taken sequentially have a high correlation with respect to one
another as in the movie mode, updating of the color temperature
data D.sub.O can be prohibited so that the hue of the main object
cannot be changed.
Further, in Step 115, the content of the counter F is checked, that
is, whether F=3 or not is checked. If F.noteq.3 is found, then the
program goes back to Step 101. However, since, the program is
initiated and this routine is first executed, F=3 has been already
obtained in Step 110. Therefore, in Step 116, the color temperature
data D.sub.T that is taken from the A/D converter 56 in Step 102 is
considered as the color temperature data D.sub.O to be used for the
white balance adjustment (at the time t.sub.1 (FIGS. 3(c), (d)),
and in Step 117 after the counter F is reset the program goes back
to Step 101. Therefore, when the program is initiated and this
routine is first executed, the color temperature data D.sub.T of
the actual field is used as the color temperature data D.sub.O in
Step 117, so that a ready white balance adjustment is possible.
Similarly, if the vertical synchronization signal VD is input at a
time t.sub.2 in Step 101, then the color temperature data D.sub.T
is input (Step 102). Furthermore, in Step 103 the difference
between the previous and current color temperature data is checked,
that is, whether or not D.sub.X.gtoreq.X is checked.
When -X<D.sub.X<X, it is considered that the color
temperature data D.sub.T remains unchanged, and the flag K is
reset. At the same time, the content of the flag K is considered as
that of the flag L and the counter F is reset (Steps 104, 109, and
111).
Also, when D.sub.X.ltoreq.-X, the flag K is reset in Step 106 and
then the program advances to Step 107 in a similar manner to the
previous case. In the illustrated embodiment, as shown in FIG.
3(d), the values of the color temperature data D.sub.T show an
ascending tendency over a period of the times
t.sub.1.about.t.sub.5, and the difference D.sub.X is considered for
this period that D.sub.X.gtoreq.X.
Therefore, in Step 103 it is decided that D.sub.X.gtoreq.X, the
flag K is set, and whether or not K=L is checked (Steps 105, 107).
Here, since the previous state of the flag K, is considered with
the flag L and L=0, in Step 107 it is decided that K.noteq.L,
because the content of the flag K(=1) is considered as the content
of the flag L, and the counter F is reset (Steps 109, 111).
Processing in Steps 112.noteq.117 are executed similarly.
At a time when the routine is executed further three times under
the state of D.sub.X.gtoreq.X after the counter F is reset
substantially at the time t.sub.2 in the above-mentioned manner. At
a time t.sub.5 when the content of the counter F is three of F=3,
the color temperature data D.sub.T that is input at the time from
the A/D converter 56 is substituted for the color temperature data
D.sub.O in Step 116. This also applies when the tendency of
D.sub.X.ltoreq.-X continues for a period the times
t.sub.1.about.t.sub.5. In other words, when the color temperature
of the field varies continuously in the same direction with a width
greater than or equal to a value (in the illustrated embodiment,
when the state of |D.sub.X|.gtoreq.X continues four cycles with
each cycle being one vertical synchronization signal VD (1/60
sec.), the color temperature data D.sub.O to be used for the white
balance adjustment is updated by the color temperature data D.sub.T
that is input at the time (in the illustrated embodiment, at the
time t.sub.5).
On the other hand, if the photographic mode is set in the movie
mode, when the state of |D.sub.X|.gtoreq.X continues 60 cycles with
each cycle being one vertical synchronization signal VD (or when
F=59), the color temperature data D.sub.O is updated by the input
color temperature data D.sub.T (Steps 118 and 116).
As described above, in the illustrated embodiment, when the color
temperature of the field varies continuously in the same direction
with a width greater than or equal to a given value, the still mode
and the movie mode are different from each other in the cycles
thereof for updating of the color temperature data D.sub.O. In
particular, in the still mode, the updating of the color
temperature data D.sub.O is executed every time T.sub.1
(=1/60.times.4=66.4 msec.) in which the vertical synchronization
signal VD is output 4 times, while, in the movie mode, the color
temperature data D.sub.O is updated every time T.sub.2
(=1/60.times.60=1 sec.) in which the vertical synchronization
signal VD is output 60 times.
According to the present embodiment, the response property, which
extends from the input of the color temperature data up to the
initiation of a processing of a signal to be used for the white
balance adjustment, can be altered properly according to the
photographic mode set.
In the present embodiment, the above-mentioned response property
according to the set photographic modes can be obtained by use of
the program that is executed by the control part 16, but the
present invention is not limited to this. For example, as shown in
FIG. 4, a response property according to the photographic modes can
be obtained by interposing between the color temperature detection
part 34 and the A/D converter 56 a low pass filter 70 having a time
constant CR which can be altered by a capacitor C, a resistor R and
an analog switch, and by switching the analog switch of the low
pass filter 70 in accordance with the photographic modes by a
control signal output from the control part 16 to thereby alter the
time constant CR of the low pass filter 70. In this case, as a
matter of fact, in the still mode the time constant of the low pass
filter 70 is set smaller than in the movie mode.
Also, although in the above-mentioned embodiment the description
has been given for a case in which the present invention is applied
to the electronic still camera, the present invention is not
limited to the electronic still camera, but, for example, the
invention can also be applied to a case in which a VTR is provided
with an electronic shutter function for still photography.
As has been described heretofore, because the present invention is
constructed such that, during the sequential photographing
operation, the updating of the color temperature data to be used
for the white balance adjustment is prohibited, according to the
invention, the homogeneity of the main object can be maintained
free from the variations of the color temperature of the field when
photographing still images in the sequential photographic mode.
Also, due to the fact that in the present invention the response
time, which extends from the detection of the field color
temperature by the color temperature detection device to the
execution of the white balance adjustment by the control device,
can be altered, according to the invention, and the white balance
can be adjusted properly according to the photographic modes.
It should be understood, however, that there is no intention to
limit the invention to the specific forms disclosed, but on the
contrary, the invention is to cover all modifications alternate
constructions and equivalents falling within the spirit and scope
of the invention as expressed in the appended claims.
* * * * *