Digital Camera Patent Abstract
A digital camera includes a CCD imager having an interline transfer
scheme. A first charge produced due to first exposure is read from
light receiving elements positioned vertically intermittently. A
second charge produced due to second exposure is also read from
the same light receiving elements to vertical transfer regions.
Here, the first charge is vertically moved simultaneously with or
prior to reading out the second charge. The moving distance, at
this time, is equal to or greater than a distance that the light
receiving elements continue in the vertical direction. As a result
of this, the second charge will not be mixed with the first charge.
The first and second charges are subjected to a compositing process
to display a composite image on an LCD. Digital Camera Patent Claims
What is claimed is:
1. A digital camera, comprising: an imager including a vertical
transfer register having a plurality of transfer areas, a horizontal
transfer register connected to an output terminal of said vertical
transfer register, and a plurality of light-receiving elements respectively
assigned to said plurality of transfer areas; a timing generator
connected to said imager, and for applying timing signals to said
imager, wherein said timing signals include a first exposure signal
for carrying out a first exposure of a first time period, a second
exposure signal for carrying out after said first exposure a second
exposure of a second time period, which is shorter than said first
time period, a first reading signal for reading-out from first light-receiving
elements intermittently present in a vertical direction out of said
plurality of light-receiving elements to said vertical transfer
register first electric charges generated by said first exposure,
a second reading signal for reading-out from second light-receiving
elements respectively assigned to vacant transfer areas in which
no electric charge is present out of said plurality of light-receiving
elements to said vertical transfer register second electric charges
generated by said second exposure, a vertical transfer signal for
transferring the electric charges read-out to said vertical transfer
register in a vertical direction, and a horizontal transfer signal
for transferring in a horizontal direction the electric charges
that reaches said horizontal transfer register by a transfer in
accordance with said vertical transfer signal, and wherein said
second light receiving elements are intermittently present in the
vertical direction, and said first electric charges read out by
said first reading signal and said second electric charges read
out by said second reading signal are alternately arranged on said
vertical transfer register; and a processor for generating one screen
of a first image signal based on said first electric charges and
said second electric charges output from said imager; an instruction
key for inputting an imaging instruction; and a shutter member arranged
at a front surface of said imager, and for cutting-off an irradiation
of light into said imager; wherein said timing signal further includes
a third exposure signal output in response to an operation of said
instruction key, and for carrying out a third exposure of a third
time period, a third reading signal for reading out from said plurality
of light-receiving elements to said vertical transfer register third
electric charges generated by said third exposure, a second vertical
transfer signal for transferring in a vertical direction said third
electric charges on said vertical transfer register, a second horizontal
transfer signal for transferring in a horizontal direction said
third electric charges applied to said horizontal transfer register,
a fourth exposure signal for carrying out a fourth exposure after
said third exposure, a driving signal output after a fourth time
period, which is different from said third time period, has passed
since a time of starting said fourth exposure, and for driving said
shutter member, a fourth reading signal for reading out fourth electric
charges generated by said fourth exposure from said plurality of
light-receiving elements to said vertical transfer register after
a completion of a vertical transfer of said third electric charges,
a third vertical transfer signal for transferring in a vertical
direction said fourth electric charges on said vertical transfer
register, and a third horizontal transfer signal for transferring
in a horizontal direction said fourth electric charges applied to
said horizontal transfer register, and said processor generating
one screen of a second image signal based on said third electric
charges and fourth electric charges output from said imager.
2. A digital camera according to claim 1, further comprising a
recorder for recording said second image signal into a recording
medium in a compressed state.
3. A digital camera, comprising: an imager including a vertical
transfer register having a plurality of transfer areas, a horizontal
transfer register connected to an output terminal of said vertical
transfer register, and a plurality of light-receiving elements respectively
assigned to said plurality of transfer areas; an exposure controller
for controlling an exposure of said imager by using an electric
shutter system; a reader for reading out from a portion of said
plurality of light-receiving elements to said vertical transfer
register electric charges generated by an exposure of said exposure
controller; a vertical transferor for transferring in a vertical
direction the electric charges read-out to said vertical transfer
register by said reader; a horizontal transferor for transferring
in a horizontal direction the electric charges that reach said horizontal
transfer register by a transfer of said vertical transferor, wherein
said exposure controller carries out a first exposure of a first
time period, and carries out after said first exposure a second
exposure of a second time period, which is shorter than said first
time period, said reader reads out from first light-receiving elements
intermittently present in a vertical direction out of said plurality
of light-receiving elements to said vertical transfer register first
electric charges generated by said first exposure, and reads out
from second light-receiving elements respectively assigned to vacant
transfer areas in which no electric charge is present out of said
plurality of light-receiving elements to said vertical transfer
register second electric charges generated by said second exposure,
and wherein said second light-receiving elements are intermittently
present in the vertical direction, and said first electric charges
and said second electric charges read out by said reader are alternately
arranged on said vertical transfer register; and a generator for
generating one screen of a first image signal based on said first
electric charges and said second electric charges output from said
imager; an instruction key for inputting an imaging instruction;
a shutter member arranged at a front surface of said imager, and
for cutting-off an irradiation of light into said imager; and a
driver for driving said shutter member, wherein said exposure controller
carries out a third exposure of a third time period in response
to an operation of said instruction key, and starts a fourth exposure
after said third exposure, said reader reads out from said plurality
of light-receiving elements to said vertical transfer register third
electric charges generated by said third exposure, and reads out
fourth electric charges generated by said fourth exposure from said
plurality of light-receiving elements to said vertical transfer
register after a completion of a vertical transfer of said third
electric charges, said driver drives said shutter member when a
fourth time period, which is different from said third period, has
passed since a time of staring said fourth exposure, and said generator
generates one screen of a second image signal based on said third
electric charges and said fourth electric charges output from said
imager.
4. A digital camera according to claim 3, further comprising a
recorder for recording said second image signal into a recording
medium in a compressed state.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to digital cameras and, more particularly,
to a digital camera which can create one screen of image signals
based on a first charge (first camera signal) produced due to first
exposure by a CCD imager and a second charge (second camera signal)
due to second exposure of the CCD imager.
2. Description of the Related Art
A digital camera employs an image sensor, such as a CCD imager,
to shoot a subject. If the CCD imager is given a subject image in
front thereof, light receiving elements produce electric charges
in proportion to the amount of light through photoelectric conversion.
The charges thus produced are outputted through the vertical and
horizontal transfer registers. By performing a predetermined signal
process on these charges (camera signal), a subject image is reproduced
on a monitor. The subject image is also recorded to a memory medium.
However, there is a limitation in the charge amount to be stored
on the light receiving elements. Consequently, if the subject image
has an extremely-high light quantity area (bright area), saturation
of charge possibly occurs in such an area. Thus, in the conventional
digital camera there has been a limitation in the dynamic range
for a shot subject image.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide
a digital camera having a dynamic range to be broadened for a taken
subject image.
A digital camera according to the present invention, comprises:
a CCD imager having light receiving elements vertically and horizontally
arranged respectively in a first predetermined number and a second
predetermined number, and including the second predetermined number
of vertical transfer registers each having the first predetermined
number of transfer regions and a horizontal transfer register connected
to output ends of the vertical transfer registers; a timing generator
connected to the CCD imager to supply predetermined timing signals
to the CCD imager, the predetermined timing signals including a
first exposure signal to perform first exposure for a first predetermined
period, a first read signal to read a first charge created due to
the first exposure from first light receiving elements positioned
vertically intermittently to the vertical transfer registers, a
charge moving signal to move the first charge to vacant transfer
regions of the vertical transfer registers, a second exposure signal
to perform second exposure for a second predetermined period different
from the first predetermined period, a second read signal to read
a second charge created due to the second exposure from second light
receiving elements positioned vertically intermittently to the vertical
transfer registers, a first vertical transfer signal to vertically
transfer the first charge and the second charge on the vertical
transfer registers, and a first horizontal transfer signal to horizontally
transfer the first charge and the second charge to the horizontal
transfer register; a first processor connected to the CCD imager
and creating one screen of a first image signal based on the first
charge and the second charge that have been outputted from the horizontal
transfer register.
According to the present invention, the CCD imager has light receiving
elements vertically in a first predetermined number and horizontally
in a second predetermined number, and includes the second predetermined
number of vertical transfer registers each having the first predetermined
number of transfer region and a horizontal transfer register connected
to output ends of the vertical transfer registers. The timing generator
supplies predetermined timing signals to the CCD imager.
First exposure for a first predetermined period is effected by
a first exposure signal. The first charge produced by the first
exposure is read by a first read signal from the first light receiving
elements positioned vertically intermittently to the vertical transfer
registers. The first charge thus read is moved to vacant transfer
regions of the vertical transfer registers by a charge moving signal.
Second exposure for a second predetermined period different from
the first predetermined period is effected by a second exposure
signal. A second charge produced due to the second exposure is read
by a second read signal from the second light receiving elements
positioned vertically intermittently to the vertical transfer registers.
The first and second charges thus read on the vertical transfer
registers are vertically transferred by a first vertical transfer
signal, being delivered to the horizontal transfer register. The
first and second charges given to the horizontal transfer register
are thereafter horizontally transferred by a first horizontal transfer
signal.
The first processor creates one screen of a first image signal
based on the first and second charges thus outputted from the horizontal
transfer register.
Because one screen of an image signal is created on a first change
produced due to a first exposure for a first predetermined period
and a second charge due to a second exposure, the dynamic range
for the shot image can be broadened.
According to one embodiment, the first light receiving elements
and the second light receiving elements are the same light receiving
elements. Also, the charge moving signal is a signal to move the
first charge simultaneously with or prior to reading out the second
charge. Here, the moving distance of the first charge is greater
than a distance that the first light receiving elements vertically
continue. When the first light receiving elements of N (N.gtoreq.1)
in number exist vertically intermittently for each, the first charge
moves over at least a distance corresponding to the first light
receiving elements of N in number.
In another embodiment of the present invention, an image corresponding
to the first image signal is displayed on the monitor connected
to the first processor.
In one aspect of the invention, when a shutter button is operated,
a third exposure signal is outputted from the timing generator.
As a result, third exposure is effected for a third predetermined
period. A third charge produced as a result of the third exposure
is read from all the light receiving elements to the vertical transfer
registers by a third read signal. The third charge read to the vertical
transfer register is vertically transferred by a second vertical
transfer signal to the horizontal transfer register. The third charge
on the horizontal transfer register is thereafter horizontally transferred
by a second horizontal transfer signal.
After the third exposure, a fourth exposure signal is outputted
from the timing generator, thereby starting fourth exposure. Elapsing
a fourth predetermined period, a shutter member is driven by a drive
signal whereby light incidence onto the CCD imager is blocked off
by the shutter member. That is, the fourth exposure ends by a mechanical
shutter scheme. A fourth charge produced as a result of the fourth
exposure, after completing vertical transfer of the third charge,
is read from all the light receiving elements to the vertical transfer
registers by a fourth read signal. The fourth charge read to the
vertical transfer registers is then vertically transferred by a
third vertical transfer signal to the horizontal transfer register.
The fourth charge on the horizontal transfer register is thereafter
horizontally transferred by a third horizontal transfer signal,
thus being outputted to the CCD imager.
A second processor creates one screen of a second image signal
based on the third and fourth charges outputted from the CCD imager.
The created second image signal is thereafter recorded in a compression
state to a recording medium.
A digital camera according to the present invention, comprises:
a CCD imager having light receiving elements vertically and horizontally
arranged respectively in a first predetermined number and a second
predetermined number, and including the second predetermined number
of vertical transfer registers each having the first predetermined
number of transfer regions and a horizontal transfer register connected
to output ends of the vertical transfer registers; a first exposure
means for giving first exposure or first predetermined period to
the CCD imager; a first read means for reading a first charge created
due to the first exposure from first light receiving elements positioned
vertically intermittently to the vertical transfer registers; a
charge moving means for moving the first charge to vacant transfer
regions of the vertical transfer registers; a second exposure means
for giving second exposure to the CCD imager for a second predetermined
period different from the first predetermined period; a second read
means for reading second charge created due to the second exposure
from second light receiving elements positioned vertically intermittently
to the vertical transfer registers; a first vertical transfer means
for vertically transferring the first charge and the second charge
over the vertical transfer registers; a horizontal transfer means
for horizontally transferring the first charge and the second charge
given to the horizontal transfer register; and a first image signal
creating means for creating one screen of a first image signal based
on the first charge and the second charge that have been outputted
from the horizontal transfer register.
According to the present invention, a CCD imager has light receiving
elements vertically and horizontally arranged respectively in a
first predetermined number and a second predetermined number, and
includes the second predetermined number of vertical transfer registers
each having the first predetermined number of transfer regions and
a horizontal transfer register connected to output ends of the vertical
transfer registers. The first exposure means causes the CCD imager
thus structured to effect first exposure for a first predetermined
period. The first read means reads the first charge produced due
to the first exposure from the first light receiving elements positioned
vertically intermittently to the vertical transfer registers. The
first charge thus read is moved to vacant transfer regions of the
vertical transfer registers by the charge moving means.
On the other hand, the second exposure means causes the CCD imager
to effect second exposure for a second predetermined period different
from the first predetermined period. The second read means reads
the second charge produced as a result of the second exposure from
the second light receiving elements positioned vertically intermittently
to the vertical transfer registers. The first and second charges
thus read to the vertical transfer registers are vertically transferred
by the first vertical transfer means. The first and second charges
when delivered to the horizontal transfer register are horizontally
transferred by the first transfer means. The first image signal
creating means creates one screen of a first image signal based
on the first and second charges outputted from the horizontal transfer
register.
Because one screen of an image signal is created based on the first
charge produced as a result of the first exposure for the first
predetermined period and the second charge as a result of the second
exposure for the second predetermined period, the dynamic range
can be broadened for a shot image.
In one embodiment of the present invention, the first light receiving
elements and the second light receiving elements are the same light
receiving elements. The charge moving means moves the first charge
simultaneous with or prior to reading out the second charge. Here,
the first charge has a moving distance greater than a distance that
the first light receiving elements vertically continue. That is,
when the first light receiving elements of N (N.gtoreq.1) in number
exist vertically intermittently for each, the first charge moving
over at least a distance corresponding to the first light receiving
elements of N in number.
In another embodiment of the present invention, the first exposure
means and the second exposure means are of an electronic shutter
scheme to provide the first exposure and the second exposure.
In still another embodiment of the present invention, an image
corresponding to the first image signal is displayed on a monitor.
In one aspect of the present invention, when a shutter button is
operated, a third exposure is effected for a third predetermined
period by a third exposure means. The third charge produced as a
result of the third exposure is read from all the light receiving
elements to the vertical transfer registers by a third read means,
and thereafter vertically transferred by a second transfer means.
When the third charge is delivered by vertical transfer to the horizontal
transfer register, a second horizontal transfer means horizontally
transfers the third charge. A fourth exposure means effects fourth
exposure after the third exposure. Elapsing a fourth predetermined
period from a start of the fourth exposure, a drive means drives
a shutter member. As a result of this, light incident onto the CCD
imager is blocked off, thus ending the fourth exposure.
The fourth charge produced as a result of the fourth exposure,
after completing vertical transfer of the third charge, is read
by a fourth read means from all the light receiving elements to
the vertical transfer registers. The read charge is vertically transferred
to the horizontal transfer register by a third vertical transfer
means. The fourth charge delivered to the horizontal transfer register
is thereafter horizontally transferred by a third horizontal transfer
means. A second image signal creating means creates one screen of
a second image signal based on the third and fourth charges outputted
from the horizontal transfer registers. The created second image
signal is recorded in a compression state to a recording medium
by a recording means.
The above described objects and other objects, features, aspects
and advantages of the present invention will become more apparent
from the following detailed description of the present invention
when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing one embodiment of the present
invention;
FIG. 2 is an illustrative view showing a CCD imager applied to
the FIG. 1 embodiment;
FIG. 3 is a block diagram showing one part of a timing generator
applied to the FIG. 1 embodiment;
FIG. 4 is a timing chart showing one part of operation in a camera
mode of the FIG. 1 embodiment;
FIG. 5 is an illustrative view showing one part of operation in
the camera mode of the FIG. 1 embodiment;
FIG. 6 is a timing chart showing one part of operation of the FIG.
1 embodiment when a shutter button is pressed;
FIG. 7 is a block diagram showing another embodiment of the present
invention;
FIG. 8 is a block diagram showing one part of a timing generator
applied to the FIG. 7 embodiment;
FIG. 9 is an illustrative view showing one part of operation in
a camera mode of the FIG. 7 embodiment;
FIG. 10 is an illustrative view showing another part of operation
in the camera mode of the FIG. 7 embodiment;
FIG. 11 is a timing chart showing one part of operation in the
camera mode;
FIG. 12 is a detailed timing chart for a period A shown in FIG.
11;
FIG. 13 is a detailed timing chart for a period B shown in FIG.
11; and
FIG. 14 is a detailed timing chart for a period C shown in FIG.
11.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, a digital camera 10 of this embodiment includes
an optical lens 12 and a shutter member 14 that mechanically operates
to block off incoming light. A subject image is given through the
optical lens 12 and shutter member 14 to a CCD imager 16 of an interline
transfer scheme. The CCD imager 16, with a resolution of XGA, includes
pixels arranged in the number of "horizontally 1280" and
vertically "960".
The CCD imager 16 is formed with a plurality of light receiving
elements 16a, as shown in FIG. 2. The light receiving elements 16a
have, in front, a primary color filter 15 having filter elements
of R, G and B arranged in a mosaic form. The light receiving elements
16a constitute pixels for the CCD imager 16, wherein each light
receiving element 16a corresponds to any of the filter elements.
The subject image is passed through the primary color filter 15
formed as above to the light receiving elements 16a for photoelectric
conversion.
The charge thus photoelectrically converted by the light receiving
element 16a is read onto a vertical transfer register 16b. The vertical
transfer registers 16b are arranged in number of horizontally 1280.
Each vertical transfer registers 16b is formed by a plurality of
metals. Three metals correspond to one light receiving element 16a,
and the three metals form one transfer region. During charge reading,
the potential on a central metal is decreased, shown by hatching,
of the three metals forming one transfer region. As a result of
this, the charge stored on each light receiving element 16a can
be read onto a vertical transfer register 16b without being mixed
with the charge of other elements. The charge thus read is vertically
transferred without being mixed with the charges of other elements,
by varying the potentials on the metals. The vertical transfer registers
16b have their output ends connected with a horizontal transfer
register 16c. The horizontal transfer register 16c, each time 1
line of charge is inputted from each vertical transfer register
16b, transfers the same charge in the horizontal direction. In this
manner, the charges stored on the light receiving elements 16a are
outputted line-by-line as a camera signal.
The charge accumulated on the light receiving element 16a is read
onto the vertical transfer register 16b in response to a charge
reading pulse XSG, and the read charge is then transferred to the
horizontal transfer register 16c in response to a vertical transfer
pulse XV1. The charge delivered to the horizontal transfer register
16c is outputted to an outside in response to a horizontal transfer
pulse XH1. Meanwhile, the charge accumulated on the light receiving
element 16a during a non-exposure period is swept out to an overflow
drain (not shown) due to a charge sweep pulse XSUB. These pulses
are outputted from timing generator (TG) 22 connected to the CCD
imager 16. These pulses are controlled in output timing by a CPU
40 whereby exposure time and the number of pixels in an output camera
signal are varied. Incidentally, the method of controlling exposure
with the charge sweep pulse XSUB or charge read pulse XSG is a well-known
technique called electronic shutter.
In a camera mode in order to display motion images real time on
an LCD 38, a charge sweep pulse XSUB, a charge read pulse XSG, a
vertical transfer pulse XVI and a horizontal transfer pulse XH1
are outputted in timing shown in FIGS. 4(B)-(C) with respect to
a vertical synchronizing signal Vsync shown in FIG. 4(A). First,
in synchronism with a vertical synchronizing signal Vsync a charge
sweep pulse XSUB is outputted to sweep away all the charges accumulated
on the light receiving element 16a. From this time, first exposure
is started and newly produced charges are accumulated on the light
receiving element 16a. Elapsing a predetermined time, a charge read
pulse XSG is outputted and the charges accumulated on a predetermined
light receiving element 16a 5 are read onto the vertical transfer
register 16b.
The LCD 38 has a resolution of VGA. In the camera mode, a camera
signal of 1280 pixels.times.140 lines provides creation of a display
image of 640 pixels.times.480 lines. As a result of this, in the
case that 8 lines are taken as 1 unit to assign VI-V8 to each line,
the charge 1 accumulated on the lines V5 and V8 is read out. In
this manner, when the charge 1 of 1280 pixels.times.140 lines has
been read out, the first exposure is ended.
Referring back to FIG. 4, immediately after ending the first exposure,
a charge sweep pulse XSUB is outputted to start second exposure
from this time. Elapsing a predetermined time, a charge read pulse
XSG as identical to the first exposure is again outputted to read
out charges of 1280 pixels.times.140 lines from the same light receiving
element 16a as in the first exposure. At this time, the second exposure
is ended. If the second exposure is ended, charge sweep pulses XSUB
are repeatedly outputted until a next first exposure is started,
consecutively sweeping away the charges accumulated on the light
receiving element 16a.
The vertical charge transfer as a result of the vertical transfer
pulse XVI and horizontal charge transfer as a result of the horizontal
transfer pulse XH1 are started simultaneously with reading out the
charges obtained by the second exposure. In the camera mode only
240 lines are used that is, 1/4 of 960 lines of light receiving
elements 16a, leaving a vacant transfer region of 720 lines to the
vertical transfer register 16b. As a result of this, as shown in
FIG. 5(B), the charge 1 based on the first exposure is vertically
moved simultaneously with reading out the charge 2 based on the
second exposure.
The light receiving element 16a to be read out are intermittently
positioned one-by-one with respect to the vertical direction, and
the moving distance of the charge 1 is at least a distance between
adjacent light receiving elements 16a. As a result of this, the
charge 1 moves to a transfer region (vacant transfer region) corresponding
to a light receiving element 16a now not to be read out. At a time
point that the charge 2 is read out, the charges 1 and 2 exist on
every other line without being mixed with each other. The charges
1 and 2 are vertically transferred in this state and then horizontally
transferred through the horizontal transfer register 16c. Through
the horizontal transfer register 16c the charge 1 (first camera
signal) and the charge 2 (second camera signal) are alternately
outputted line-by-line.
Referring to FIG. 1, the first camera signal and the second camera
signal outputted from the CCD imager 16 are subjected to well-known
noise removal and level adjustment by a CDS/AGC circuit 18, and
then converted into first camera data and second camera data by
an A/D converter 20.
In the camera mode, a switch SW1 is switched between a terminal
S2 and a terminal S3 at a time interval of 1-line period. Also,
a switch SW2 is connected to a terminal S5. Both the switches SW1
and SW2 are controlled by a CPU 40. The first camera data and the
second camera data coexist every line. Consequently, a 2-screen
composting circuit 32 is inputted by the first camera data with
1-line delay through a line memory 30 and the second camera data
without delay. That is, the first camera data and second camera
data on a same line are simultaneously inputted to the 2-screen
compositing circuit 32. Incidentally, the writing to and reading
from the line memory 30 are controlled by a memory control circuit
24.
The 2-screen compositing circuit 32 selects a signal having a brightness
satisfying a predetermined condition from the simultaneously-inputted
first and second camera data. In this embodiment, the first exposure
time is greater than the second exposure time, and, accordingly,
the second camera data is employed for a subject high brightness
portion while the first camera data is for a low brightness portion.
In this manner, composite camera data is created having 1280 pixels.times.240
lines that is broadened in dynamic range in a pseudo fashion. The
composite camera data is thereafter subjected to YUV conversion,
thinning-out, interpolation and the like by a signal processing
circuit 34, and thereby created into image data having 640 pixels.times.480
lines. The created image data is outputted into the LCD 38. As a
result, real time motion pictures (through pictures) are displayed.
If an operator manipulates a shutter button 42, the CPU 40 supplies
to the TG 22 a picture taking instruction signal shown in FIG. 6(A).
The TG 22, in turns, outputs a charge sweep pulse XSUB, a charge
read pulse XSG, a shutter drive signal, a vertical transfer pulse
XV1 and a horizontal transfer pulse XH1 respectively shown in FIGS.
6(B)-(F).
That is, nearly simultaneously with a picture taking instruction,
a charge sweep pulse XSUB is outputted almost simultaneously with
the picture taking instruction, to start third exposure. Elapsing
a predetermined period, a charge read pulse XSG is outputted to
read charges of 1280 pixels.times.960 lines from all the light receiving
elements 16a onto the vertical transfer registers 16b. At this time,
the third exposure is ended. When the shutter button 42 is operated,
charges are read from all the light receiving elements 16a. Accordingly,
no vacant areas are formed on the vertical transfer registers 16b,
differently from the camera mode. A vertical transfer pulse XVI
and horizontal transfer pulse XH1 are outputted immediately after
ending the third exposure. The third charge, or third camera signal,
read out onto the vertical transfer registers 16b is promptly outputted
through the horizontal transfer register 16c.
Immediately after outputting a charge read pulse XSG, a charge
sweep pulse XSUB is outputted to start fourth exposure nearly simultaneously
with the start of vertical transfer. Elapsing a predetermined time
from a start of the fourth exposure, a shutter drive signal rises
to drive a shutter member 14. As a result of this, incident light
is blocked off, thus ending the fourth exposure. In this manner,
third exposure starting and ending as well as fourth exposure starting
are controlled by an electronic shutter scheme. However, fourth
exposure ending is controlled by a mechanical shutter scheme.
With a mechanical shutter scheme, the incidence of light onto the
CCD imager 16 is actually blocked off by the shutter member 14 arranged
in front of the CCD imager 16. Accordingly, there is no need to
read out charges immediately after elapsing an exposure period.
Thus, even after closure of the shutter member 14, the charges are
held on the light receiving elements 16a. After completing vertical
and horizontal transfer of the third charge based on third exposure,
a charge read pulse XSG is outputted. As a result of the charge
read pulse XSG, a fourth charge of 1280 pixels.times.960 lines based
on fourth exposure is read out of the light receiving elements 16a.
Because after completing the reading out, the shutter member 14
is no longer required to be closed, the shutter drive signal is
fallen to open the shutter member 14. Meanwhile, immediately after
reading the third charge out of the light receiving elements 16a,
a vertical transfer pulse XVI and horizontal transfer pulse XH1
are outputted. Thus, a fourth charge, i.e., fourth camera signal,
based on fourth exposure is outputted.
In this manner, when the shutter button 42 is operated, a third
camera signal and a fourth camera signal are individually outputted
from the CCD imager 16. The output third camera signal and fourth
camera signal are respectively converted into third camera data
and fourth camera data through the processing of CDS/AGC, similarly
to the above. The CPU 40 causes the switch SW1 to connect to the
terminal SI when third camera data is outputted from the A/D converter
20. The third camera data is written onto the frame memory 28 by
the memory control circuit 24. When all the third camera data is
written onto the frame memory 28, the CPU causes the switch SW1
to connect to the terminal S3. Accordingly, the fourth camera data
to be outputted following the third camera data from the A/D converter
20 is directly inputted to the 2-screen compositing circuit 32.
The 2-screen compositing circuit 32 composites together the third
camera data and the fourth camera data in a manner similar to the
above, thereby creating composite camera data having 1280 pixels.times.960
lines that is broadened in dynamic range in a pseudo fashion. The
signal processing circuit 34 performs YUV conversion on the composite
camera data and compresses the resulting YUV data by a JPEG scheme.
The compressed image data is then recorded in a recording media
36.
Now explained in detail will be the operation of TG 22 responsive
to shutter button 42 operation with reference to FIG. 3. A picture
taking instruction signal is supplied to a reset terminal of a counter
22b through an inverter 22a, thereby resetting a counter 22b. Meanwhile,
a clock twice the horizontal transfer pulse XH1 is given to a clock
terminal of the counter 22b, whereby a count value is incremented
by this clock. The count value thus given is inputted to decoders
22c-22g. The recorders 22c-22g respectively produce a charge sweep
pulse XSUB, a charge read pulse XSG, a shutter drive signal, a vertical
transfer pulse XV1 and a horizontal transfer pulse XH1 shown in
FIGS. 6(B)-(F), in response to the count value input. That is, the
decoders 22c-22g are enabled by the CPU 40 responsive to an operation
of the shutter button 42.
Referring to FIG. 7, a digital camera 10 of another embodiment
has a TG 22 to which a TG shown in FIG. 8 is applied. In a camera
mode, a first camera signal and second camera signal having 1280
pixels.times.480 lines are read from the CCD imager 16. The line
memory 30 has a capacity of 2 lines. The 2-screen compositing circuit
34 creates composite camera data of 1280 pixels.times.480 lines
from first camera data outputted from the line memory 30 and second
camera data outputted from the A/D converter 20. Furthermore, the
signal processing circuit 34 creates image data of 640 pixels.times.480
lines based on the composite camera data of 1280 pixels.times.480
lines, and supplies it to the LCD 38. As a result, through-images
are displayed on the LCD 38 which is broadened in dynamic range
in a pseudo fashion.
Referring to FIG. 8, the TG 22 includes an H counter 22h and a
V counter 22i. The H counter 22h is to count the number of horizontal
pixels. A horizontal count value is reset in response to a horizontal
sync signal and decremented responsive to a pixel clock. On the
other hand, the V counter 22i is to count the number of vertical
lines. A vertical count value is reset in response to a vertical
sync signal and incremented responsive to a horizontal synchronizing
signal. Both the horizontal and vertical count values are delivered
to the decoders 22j-22s.
The decoder 22j creates a charge sweep pulse SUB based on these
count values. Also, the decoder 22k creates a horizontal transfer
pulse H1(H1 pulse) from the input count values. The decoders 22m
and 22n create a vertical transfer pulse V1 (V1 pulse) and vertical
transfer pulse V3 (V3 pulse) from the count values. Furthermore,
the decoders 22p-22s respectively create timing pulses XV2A, XSGA,
XV2B and XSGB. Among them the timing pulses XV2A and XSGA are delivered
to a driver 22t, while the timing pulses XV2B and XSGB are given
to a driver 22u. The drivers 22t and 22u respectively create a vertical
transfer pulse V2A (V2A pulse) and a vertical transfer pulse V2B
(V2B pulse) based on the given timing pulses. Incidentally, FIG.
8 shows only the blocks related to the camera mode.
As stated before, each light emitting element 16a of the CCD imager
16 correspond to three metals. The vertical transfer pulses VI,
V3, V2A and V2B outputted from the TG 22 are applied to the respective
metals in a manner shown in FIG. 9 and FIG. 10. That is, considering
three metals assigned to each light receiving element 16a, a VI
pulse is applied to an uppermost metal and a V3 pulse is to a central
metal. A V2A or V2B pulse is applied to a lowermost vertical transfer
pulse. The ones to which the VIA and V2B pulses are applied are
switched every 2 pixels. That is, FIG. 9 shows pixels on an odd
numbered column. On the odd numbered column, for the vertically
continuing R pixel, G pixel, R pixel and G pixel, a V2A pulse is
supplied to the upper half, i.e. the R pixel and G pixel while a
V2B pulse is given to the lower half, i.e., the R pixel and G pixel.
FIG. 10 shows pixels on an even numbered column. Herein, a V2A pulse
is supplied to the G pixel and B pixel as the upper half of continuing
4 pixels while a V2B pulse is given to the lower half G pixel and
B pixel.
Explanation will be made on the output timings of the vertical
transfer pulses VI, V3, V2A and V2B with reference to FIG. 11 to
FIG. 14. In a duration A immediately after conducting long-time
exposure (first exposure) shown in FIG. 11, the respective pulses
vary as shown in FIG. 12. When the V2A pulse becomes a plus in level,
the first charge on a corresponding pixel is read onto the vertical
transfer register 16b. After read out, the VI and V3 pulses assume
twice a pulse level in different timing from each other. Also, the
V2A and V2B pulses simultaneously assume twice a minus level. As
a result of this, the first charge is vertically moved by 2 lines.
According to FIG. 9, respective charges R4L and G4L are read from
the pixels R4 and G4 while respective charges R2L and G2L are read
from the pixels R2 and G2. The read charges R4L, G4L, R2L and G2L
are vertically moved by 2 lines. Also, according to FIG. 10, respective
charges G4L and B4L are read from the pixels G4 and B4 while respective
charges G2L and B2L are read from the pixels G2 and B2. The charges
G4L, B4L, G2L and B2L are also vertically moved by 2 lines.
The pixels (light receiving element) to be read are only the upper-half
2 pixels among vertically continuing 4 pixels, and the lower-half
2 pixels are not to be read. That is, the light receiving elements
to be read intermittently exist every 2 pixels, and the number of
pixels of a lacking portion is also 2 pixels. Consequently, due
to the afore-said 2-lines movement the charge is positioned to a
vacant transfer region.
Short-time exposure (second exposure) is started immediately after
reading out the charge in the period A. As a result of this, the
charge is again accumulated on each light receiving element 16a.
In a period B beginning from the completion of short-time exposure,
the pulses vary as shown in FIG. 13. First, the V2A pulse becomes
once a plus level, and the charge on a corresponding pixel is read
onto the vertical transfer register 16b. On an odd numbered column
shown in FIG. 9, respective charges R4S and G4S are read out of
adjacent pixels R4 and G4, and respective charges R2S and G2S are
read from the pixels R2 and G2 adjacent through a distance of 2
pixels. On the other hand, on an even numbered column shown in FIG.
10, respective charges G4S and B4S are read out of adjacent pixels
G4 and B4, and respective charges G2S and B2S are read from the
pixels G2 and B2 adjacent through a distance of 2 pixels.
The charge read out during the period A (first charge), at a time
point of short-time exposure completion, has vertically moved by
2 lines. Thus, the charge read out during the period B (second charge)
is not mixed with the charge read during the period A. The first
and second charges thus read exist on a 2-pixel basis with respect
to the vertical direction. That is, according to FIG. 9, the first
and second charges exist in a form of R4S, G4S, R41, G4L . . . According
to FIG. 10, the first and second charges exist in a form of G4S,
B4S, G41, B4L . . . .
Referring back to FIG. 13, after the second charge has read onto
the vertical transfer register 16b, the V1 and V2 pulses assumes
only once a plus level in different timing while the V2A and V2B
pulses simultaneously assume once a minus level. Due to this, the
charges existing on the vertical transfer register 16b (first and
second charges) are vertically transferred by 1 line.
In the period C the pulses vary as shown in FIG. 14. First, the
VI pulse becomes once a plus level, and then the V2A and V2B pulses
simultaneously become once a minus level. Thereafter, the V3 pulse
becomes once a plus level. As a result of this, the charge on the
vertical transfer register 16b is vertically transferred by 1 line.
That is, the first and second charges are vertically transferred
each 2 lines in a coexisting fashion. Thereafter, vertical transfer
pulses VI, V2A, V2B and V3 are outputted in a procedure as shown
in FIG. 14, and the charge on each line is transferred toward the
horizontal transfer register 16c.
Incidentally, charge sweep pulses SUB are outputted once per each
start of the first exposure and second exposure, and further continuously
outputted from an end of the second exposure to a start of the next
first exposure.
The first or second charge delivered to the horizontal transfer
register 16c is then horizontally transferred by an HI pulse and
outputted line by line from the CCD imager 16. At this time, a first
camera signal continues over a 2-line period, and subsequently a
second camera signal continues over a 2-line period. The switch
SW1 is switched between the terminals S2 and S3 every 2-line period.
As a result of this, the first camera data outputted from the A/D
converter 20 is supplied to the 2-screen compositing circuit 42
via a line memory 30. Similarly, the second camera data outputted
from the A/D converter 20 is given as it is to the 2-screen compositing
circuit 32. That is, first and second camera data related to each
other are simultaneously inputted to the 2-screen compositing circuit
32.
The 2-screen compositing circuit 32 composites the simultaneously-inputted
first and second camera data to create composite camera data having
a dynamic range broadened in a pseudo fashion. The created composite
camera data has pixels in number of 1280 pixels.times.480 lines.
A signal processing circuit 34 creates image data of 640 pixels.times.480
lines, based on the composite camera data. The created image data
is sent to an LCD 38. As a result, through-pictures are displayed
on the screen.
According to these embodiments, in the camera mode first and second
exposures are carried out by the electronic shutter scheme. The
first charge created by the first exposure is read from the vertically-intermittent
light receiving elements to the vertical transfer registers. The
second charge created by the second exposure is also read from the
vertically-intermittent light receiving elements to the vertical
transfer registers.
Here, the light receiving element from which the first charge is
to be read out is the same as the light receiving element that the
second charge is to be read out. The first charge is transferred
to a vacant transfer region of the vertical transfer register simultaneously
with or prior to reading out the second charge. Furthermore, the
moving distance of the first charge is equal to or greater than
a distance between the light receiving elements to be read out.
As a result of this, there is no possibility that the first and
second charges be mixed with each other.
Also, when the shutter button is pressed, light incident onto the
CCD imager is actually blocked off by the mechanical shutter scheme.
This eliminates the necessity to read out the charge immediately
after exposure ending. The charges can be held on the light receiving
elements. That is, a fourth exposure can be made even while a third
camera 5 signal is third exposure. Thus, it is possible to bring
close in timing the third exposure and fourth exposure in timing
each other. As a result, even where the subject is moving at high
speed, blurring is prevented from occurring in the record image.
Incidentally, although in this embodiment explanation was made
using a primary color filter having R, G and B arranged in a mosaic
form, a complementary color filter may be used which having Ye,
Cy, Mg and G arranged in a mosaic form.
Also, in this embodiment the light receiving element from which
the first charge is to be read out (first light receiving element)
is common to the light receiving element that the second charge
is to be read out (second light receiving element). Alternatively,
the first light receiving element and the second light receiving
element may be different from each other provided that no mixing
occur between the first charge and the second charge.
Furthermore, in this embodiment the first exposure period was longer
than the second exposure. However, the second exposure period may
be set longer than the first exposure period provided that the respective
periods are different.
Furthermore, the first exposure and second exposure by the electronic
shutter scheme as well as the compositing process with the first
and second camera data based on the exposures are implemented only
in a camera mode, i.e., a through-image display mode. However, such
process is applicable also to a motion-image record mode to record
moving images to a recording medium.
Although the present invention has been described and illustrated
in detail, it is clearly understood that the same is by way of illustration
and example only and is not to of limitation, the spirit and scope
of the present invention being limited of the appended claims.
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