JPH09107550A - Solid-state image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain black balance adjustment by automatically following deterioration in an image pickup signal due to a temperature change or the like of circuit components even during image pickup. SOLUTION: A microcomputer 14 controls an electronic shutter for each field period via a shutter controller 13. A CCD image sensor 1 outputs an image pickup signal of an object and a back level image pickup signal in response to control of the electronic shutter. The outputted image pickup signal is fed to a selection circuit 9 via a register 2 on one hand and fed to the selection circuit 9 via a register 4 and a field memory 7 or the like with a delay of one field period on the other hand. The microcomputer 14 controls the selection circuit 9 to select the image pickup signal of an object and the black level image pickup signal from the two image pickup signals fed to the selection signal 9 and adjusts the black balance of the image pickup signal based on the black level image pickup signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device which adjusts black balance and outputs an image pickup signal.

[0002]

2. Description of the Related Art Generally, in a solid-state image pickup device, an image pickup signal obtained from the solid-state image pickup device may be deteriorated due to a change in temperature of a circuit element. Therefore, the solid-state imaging device
The color signal of the subject is adjusted so that the maximum sensitivity and color reproduction can be obtained in the situation of capturing an image, and then the image signal of good image quality is output. The solid-state imaging device performs black balance adjustment as one of the adjustments of each color signal.

The black balance adjustment is to sample the black level of an image pickup signal and correct the signal level according to the black level so that the black levels of the respective color signals become equal.

[0004]

In the conventional black balance adjustment, the black level of the image pickup signal is sampled by closing the shutter of the lens once. Therefore, the solid-state imaging device cannot perform black balance adjustment during imaging of a subject. Therefore, when heat generated from a circuit element or environmental temperature change occurs during imaging of a subject, the solid-state imaging device outputs the heat. The change in the signal level of the image pickup signal cannot be tracked, and a deteriorated image pickup signal may be output.

Further, since the user cannot adjust the black balance while the subject is being imaged by the solid-state image pickup device, there is an inconvenience that the image pickup must be interrupted in order to adjust the black balance.

The present invention has been made in view of the above circumstances, and automatically adjusts the black balance even when an image is being picked up by automatically following the deterioration of the image pickup signal due to the temperature change of the circuit element. It is an object of the present invention to provide a solid-state image pickup device that outputs an image pickup signal with good image quality.

[0007]

In order to solve the above-mentioned problems, a black balance adjusting apparatus according to the present invention includes a solid-state image pickup device which outputs image pickup signals of all pixels according to image pickup light every one field period. The shutter means for controlling the image pickup signal output from the solid-state image pickup device into the image pickup signal of the subject and the image pickup signal of the black level and the image pickup signal output from the solid-state image pickup device for each field period. 1
An image pickup signal of a subject is obtained from a delay unit that delays and outputs a field period, an image pickup signal output from the solid-state image pickup device, and an image pickup signal output from the solid-state image pickup device and delayed by one field period. Selection means for selecting an image pickup signal of black level, black balance adjustment means for adjusting the signal level of the image pickup signal based on the image pickup signal of black level, and image pickup of a subject from the solid-state image pickup device every one field period And a control unit for controlling the black balance adjusting unit so as to adjust the signal level of the image pickup signal.

The solid-state image pickup device uses the image pickup signal output from the solid-state image pickup element and the image pickup signal output from the solid-state image pickup element and delayed by one field period to obtain an image pickup signal of a subject and a black level. And the black balance adjustment of the image pickup signal based on the image pickup signal of the black level.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a solid-state image pickup device according to the present invention will be described below with reference to the drawings.

The solid-state image pickup device according to the present invention can be applied to, for example, a single plate type camera device.

In this single plate type camera device, for example, as shown in FIG. 1, all pixels are changed to red (R),
A CCD image sensor 1 that outputs time-divided color signals of green (G) and blue (B) to two lines as imaging signals;
Registers 2 and 4 that output the signal charge from the CCD image sensor 1 as an image pickup signal, and correlated double sampling (hereinafter, referred to as “CDS”) that reduces random noise from the image pickup signal.
Circuit 3, 5 and analog / digital (hereinafter,
"A / D" converter 6, field memory 7 acting as a delay circuit, D / A converter 8, and selection circuit for selecting an image pickup signal of a subject and an image pickup signal of black level from the image pickup signal. 9, a pedestal control circuit 10 and 12 for adjusting black balance, a sample hold (hereinafter referred to as “S / H”) circuit 11, a shutter controller 13 for controlling an electronic shutter (not shown) included in the CCD image sensor 1. A microcomputer (hereinafter, referred to as a "microcomputer") 14 for controlling the entire single plate type camera device.

In the single plate type camera device configured as described above, when the image of the subject is taken, the CCD image sensor 1
Outputs the image pickup signals of all pixels to two lines in one field period. At this time, the microcomputer 14 controls the electronic shutter via the shutter controller 13 so as to forcibly discard the image pickup signal every one field period. As a result, when the electronic shutter is open, the CCD image sensor 1 outputs, for example, the image pickup signal of the pixel in the odd field from the register 2, and the image pickup signal of the pixel in the even field from the register 4, for example. Is output. Then, the CCD image sensor 1 switches the fields to be read by the registers 2 and 4 every time all pixels are read. The image pickup signals thus output from the CCD image sensor 1 are supplied to the CDS circuits 3 and 5 via the registers 2 and 4, respectively.

The CDS circuit 3 reduces random noise from the supplied image pickup signal and supplies the image pickup signal to the selection circuit 9 as shown in FIG. 2A.

The CDS circuit 5 reduces random noise from the supplied image pickup signal and supplies the image pickup signal to the A / D converter 6 as shown in FIG. 2B. The A / D converter 6 converts the supplied image pickup signal into image pickup data and supplies the image pickup data to the field memory 7. The field memory 7 once stores the supplied imaging data of the subject, then reads the imaging data, and supplies the imaging data to the D / A converter 8. Here, the field memory 7 takes one field period from the storage of the imaging data to the reading of the imaging data. Therefore, the field memory 7 functions as a delay circuit. The D / A converter 8 converts the supplied image pickup data into an image pickup signal, and supplies the image pickup signal delayed by one field period to the selecting circuit 9 as shown in FIG. 2B ′.

The selection circuit 9 is connected to the terminals a and d connected to the CDS circuit 3, the terminals b and c connected to the D / A converter 8, and the pedestal control circuits 10 and 12. Two switches 9a and 9b which depend on each other are provided. When the switch 9a is at the terminal a, the switch 9b is at the terminal c and the switch 9a is at the terminal b.
When the switch is on, the switch 9b is switched to the terminal d.

The selection circuit 9 switches the switches 9a and 9b for each field period by a controller (not shown) so as to select the supplied two image pickup signals into an image pickup signal of a subject and an image pickup signal of a black level. , Figure 2D
The black-level image pickup signal is supplied to the pedestal control circuit 10 as shown in FIG. 2, and the subject image pickup signal is supplied to the pedestal control circuit 12 as shown in FIG. 2C.

That is, this single plate type camera device has a CC
By dividing the image pickup signal obtained from the D image sensor 1 into the image pickup signal of the subject and the image pickup signal of the black level for each field,
Based on the image signal of the black level, it is possible to adjust the black balance of the image signal of the subject, which will be described later.

Here, before adjusting the black balance,
The pedestal control circuits 10 and 12 prevent the signal level of the supplied imaging signal from varying even when the gain changes from 0 dB to 18 dB.
Perform black level correction. Since the CCD image sensor 1 obtains each color signal in a time division manner as described above, the microcomputer 1
In No. 4, black level correction is performed for the R signal first, and then for the B signal and G signal.

Specifically, the pedestal control circuit 10 samples the R signal of the supplied black level image pickup signal by the S / H circuit 11, and then supplies it to the microcomputer 14.

When the signal level of the R signal changes according to the change when the gain of the pedestal control circuit 10 is changed from 0 dB to 18 dB, the microcomputer 14 outputs a correction signal for correcting the change in the signal level. , And to the pedestal control circuit 10, and at the same time, the same correction signal is supplied to the pedestal control circuit 12. Then, the microcomputer 14 can avoid the fluctuation of the R signal at the black level even if the gains of the pedestal control circuits 10 and 12 change, and
It is also possible to avoid fluctuations in the R signal of the subject.

Similarly, the microcomputer 14 also performs black level correction on the B and G signals supplied to the pedestal control circuits 10 and 12, and as a result, even if the gain of the pedestal control circuit 10 changes, the black level is corrected. The image pickup signal can be stabilized.

Next, the microcomputer 14 adjusts the black balance so that the black levels of the R, G, and B color signals for which the black level has been corrected become equal.

Specifically, as shown in FIG. 3, in step S1, the microcomputer 14 samples the G signal supplied to the pedestal control circuit 10 by the S / H circuit 11 and then outputs the G signal. The signal level is stored in the microcomputer 14, and the process proceeds to step S2.

At step S2, the microcomputer 14
After the R signal supplied to the pedestal control circuit 10 is sampled by the S / H circuit 11, the signal level of the R signal is stored in the microcomputer 14, and the process proceeds to step S3.

In step S3, the microcomputer 14
The difference between the signal levels of the G signal and the R signal is obtained, and if it is determined that the difference is zero, the process proceeds to step S4. If it is determined that the difference is not zero, the process proceeds to step S6.

In step S4, the microcomputer 14
The B signal supplied to the pedestal control circuit 10 is sampled by the S / H circuit 11, the B signal is stored, and the process proceeds to step S5.

In step S5, the microcomputer 14
The difference between the signal levels of the G signal and the B signal is obtained, and when it is determined that the difference is zero, the adjustment of the black balance is ended. On the other hand, when it is determined that the difference is not zero, the process proceeds to step S7. move on.

In step S6 when it is determined that the difference is not zero in step S3, the microcomputer 14
Is an adjustment signal for adjusting the pedestal level so that the difference becomes zero, not only in the pedestal control circuit 10 but also in the pedestal control circuit 1.
2 is also supplied, and the process returns to step S2. As a result, not only the G signal and R signal at the black level become equal, but also the G signal and R signal of the subject become equal.

In step S7 when it is determined in step S5 that the difference is not zero, the microcomputer 14
Is an adjustment signal for adjusting the pedestal level so that the difference becomes zero, not only in the pedestal control circuit 10 but also in the pedestal control circuit 1.
2 is also supplied, and the process returns to step S4. As a result, not only the signal levels of the G signal and the R signal in the black level image pickup signal become equal, but also the signal levels of the G signal and the R signal in the image pickup signal of the subject become equal.

The image signal of the subject whose black balance has been adjusted in this way is output from the pedestal control circuit 12 as a standard signal of, for example, the NTSC system via a color separation circuit, a process circuit, an encoder and the like (not shown). .

As described above, this single plate type camera device is
Even if the subject moves during imaging of the subject and the color temperature of the subject changes, it is possible to output the image signal with black balance adjustment following the change in the signal level of each color signal. In other words, the single-plate type camera device can automatically adjust the black balance without interrupting the image pickup of the subject, so that the operation can be simplified.

Next, the second solid-state imaging device according to the present invention will be described.
An embodiment will be described.

The solid-state image pickup device can be applied to, for example, a three-plate type camera device, and the three-plate type camera device will be described below.

Note that the same circuits as those described in the first embodiment are designated by the same reference numerals, and any one of R, G, and B corresponding to each color signal is added.

Regarding the same operation for each color signal, only the operation for one color signal will be described, and the operation for the other color signals will be omitted.

As shown in FIG. 4, for example, the three-plate type camera device is arranged corresponding to each of the image pickup lights converted into the three primary color lights of R, G, and B, and the color signals of all pixels are formed in one field period. Of the three CCD image sensors 1R, 1G, 1B for outputting the two lines and the CCD image sensor 1
Registers 2R, 2G, 2B and registers 4R, 4G, 4 for outputting the signal charges from R, 1G, 1B as color signals.
B, CDS circuits 3R, 3G, 3B for reducing random noise from each color signal, and CDS circuits 5R, 5G, 5B,
A / D converters 6R, 6G, 6B, field memories 7R, 7G, 7B functioning as delay circuits, and D / A
Converters 8R, 8G, 8B and a selection circuit 9 for selecting a color signal of a subject and a color signal of a black level from each color signal.
R, 9G, 9B and pedestal control circuits 10R, 10G, 1 for adjusting the black balance of each color signal
0B and pedestal control circuits 12R, 12G,
12B, S / H circuits 11R, 11G, 11B for sampling each color signal, and a liquid crystal shutter 15 described later.
Shutter controller 1 for controlling R, 15G, 15B
3 and the liquid crystal shutters 15R, 1 for entering and blocking the image pickup light entering the CCD image sensors 1R, 1G, 1B.
5G and 15B, and a microcomputer 16 that controls the entire three-plate type camera device.

In the three-plate type camera device configured as described above, when a subject is imaged, for example, the CCD image sensor 1R outputs R signals of all pixels to two lines in one field period. At this time, the microcomputer 16 controls opening / closing of the liquid crystal shutter 15R via the shutter controller 13 for each field period. This allows CC
When the liquid crystal shutter 15R is open, the D image sensor 1R outputs, for example, the R signal of the pixel in the odd field from the register 2R, and the R signal of the pixel in the even field from the register 4R, for example. It Then, the CCD image sensor 1R switches the fields to be read by the registers 2R and 4R every time all pixels are read. In this way, the R signal output from the CCD image sensor 1R is
Through the registers 2R and 4R, the CDS circuit 3
It is supplied to R and 5R.

The CDS circuit 3R reduces random noise from the supplied R signal and supplies the R signal to the selection circuit 9R as shown in FIG. 2A.

The CDS circuit 5R reduces random noise from the supplied R signal and outputs the R noise as shown in FIG. 2B.
The signal is supplied to the A / D converter 6R. A / D converter 6R
Converts the supplied R signal into R data and supplies the R data to the field memory 7R. The field memory 7R once stores the supplied R data of the subject, reads the R data, and supplies the R data to the D / A converter 8R. Here, the field memory 7R is
It takes one field period from the storage of R data to the reading of it. Therefore, the field memory 7R functions as a delay circuit. The D / A converter 8R converts the supplied R data into an R signal, and supplies the R signal delayed by one field period to the selection circuit 9R as shown in FIG. 2B '.

The selection circuit 9R is connected from the CDS circuit 3R to the terminals a and d, the D / A converter 8R to the terminals b and c, and the pedestal control circuits 10R and 12R. The switch 9R is provided with two switches 9Ra and 9Rb which depend on each other.
When a is at the terminal a, the switch 9Rb is switched to the terminal c, and when the switch 9Ra is at the terminal b, the switch 9Rb is switched to the terminal d.

The sorting circuit 9R switches the switches 9Ra and 9Rb for each field period by a controller (not shown) so as to sort the supplied two R signals into the R signal of the object and the R signal of the black level. . Then, as shown in FIG. 2D, the selection circuit 9R supplies the black level R signal to the pedestal control circuit 10R, and
As shown in FIG. 2C, the R signal of the subject is supplied to the pedestal control circuit 12R.

That is, this three-plate type camera device has a CC
By dividing the R signal obtained from the D image sensor 1R into the R signal of the subject and the R signal of the black level for each field, even while the subject is being imaged, It is possible to adjust the black balance described later for each color signal of the subject.

Here, before adjusting the black balance,
Even if the gain of the pedestal control circuits 10R and 12R is changed from 0 dB to 18 dB,
Black level correction is performed so that the signal level of the supplied R signal does not fluctuate.

More specifically, the pedestal control circuit 10R samples the supplied black level R signal by the S / H circuit 11R and then supplies the sampled signal to the microcomputer 16. The microcomputer 16 uses the pedestal control circuit 10
If the signal level of the R signal changes according to the change when the gain of is changed from 0 dB to 18 dB, a correction signal for correcting the change in the signal level is supplied to the pedestal control circuit 10R, and at the same time, the pedestal control is performed. The same correction signal is supplied to the circuit 12R.

The microcomputer 16 can stabilize the fluctuation of the black level R signal even when the gains of the pedestal control circuits 10 and 12 change, and also stabilize the R signal of the subject. it can.

At this time, the microcomputer 16 corrects the black level of the R signal and at the same time corrects the black level of each of the G and B color signals, based on the black level of each of the R, G and B color signals. Adjustment.

Specifically, as shown in FIG. 3, in step S1, the microcomputer 16 sends the G signal supplied to the pedestal control circuit 10G to the S / H circuit 11G.
Sampling with, the signal level of G signal
Stored in 6 and proceed to step S2.

At step S2, the microcomputer 16
The R signal supplied to the pedestal control circuit 10R is sampled by the S / H circuit 11R, the signal level of the R signal is stored in the microcomputer 16, and step S
Proceed to 3.

In step S3, the microcomputer 16
The difference between the signal levels of the G signal and the R signal is obtained, and if it is determined that the difference is zero, the process proceeds to step S4. If it is determined that the difference is not zero, the process proceeds to step S6.

At step S4, the microcomputer 16
The B signal supplied to the pedestal control circuit 10B is sampled by the S / H circuit 11B, the signal level of the B signal is stored in the microcomputer 16, and step S5
Proceed to.

In step S5, the microcomputer 16
The difference between the signal levels of the G signal and the B signal is obtained, and when it is determined that the difference is zero, the adjustment of the black balance is ended. On the other hand, when it is determined that the difference is not zero, the process proceeds to step S7. move on.

In step S6 when it is determined that the difference is not zero in step S3, the microcomputer 16
Is an adjustment signal for adjusting the pedestal level so that the difference becomes zero, not only for the pedestal control circuit 10R but also for the pedestal control circuit 12R.
Is also supplied, and the process returns to step S2. As a result, not only the black level G and R signals become equal, but
The signal and the R signal are equal.

In step S7 when it is determined in step S5 that the difference is not zero, the microcomputer 16
Is an adjustment signal for adjusting the pedestal level so that the difference becomes zero, not only in the pedestal control circuit 10B but also in the pedestal control circuit 12B.
Is also supplied, and the process returns to step S4. As a result, not only the black level G signal and B signal become equal, but
The signal and the B signal become equal.

By equalizing the black level of each color signal in this way, the image signal composed of each color signal of the subject whose black balance has been adjusted is supplied from the pedestal control circuit 12 to a color separation circuit, a process circuit, not shown.
For example, it is output as an NTSC standard signal via an encoder or the like.

As described above, in the three-plate type camera device, even if the subject moves during image pickup of the subject and the color temperature of the subject changes, the black balance is adjusted by following the change in the signal level of each color signal. An image pickup signal can be output. In other words, the three-plate type camera device can automatically adjust the black balance without interrupting the image pickup of the subject, so that the operation can be simplified.

In addition, the three-plate type camera device outputs the imaging light to R,
CCD image sensor 1 by separating into G and B color signals
By forming each image on the photosensitive surface of R, 1G, and 1B, the image pickup light can be basically used without loss, the SN ratio is good, and high resolution is obtained. Since the color filter characteristics are independently determined, color reproduction is good.

In the first embodiment, the example in which the electronic shutter is combined with the single plate type camera device and the example in which the liquid crystal shutter is combined with the three plate type camera device is described in the second embodiment. Of course, the present invention is not limited to these combinations.

[0058]

As described in detail above, in the solid-state image pickup device according to the present invention, the image pickup signal outputted from the solid-state image pickup device and the image pickup signal outputted from the solid-state image pickup device are picked up while the subject is being picked up.
It is possible to select the image pickup signal of the subject and the image pickup signal of the black level from the image pickup signal delayed for the field period, and perform the black balance adjustment of the image pickup signal based on the image pickup signal of the black level.

That is, this solid-state image pickup device can automatically follow the change in the signal level of each color signal even if the color temperature of the subject changes during the image pickup of the subject, and thus the convenience of operation is improved. Can be planned.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a specific configuration of a single plate type camera device to which a solid-state imaging device according to the present invention is applied.

FIG. 2 is a timing chart for explaining an operating state of the solid-state imaging device.

FIG. 3 is a flowchart for explaining black balance adjustment in the solid-state imaging device and the like.

FIG. 4 is a block diagram showing a specific configuration of a three-plate type camera device to which the solid-state imaging device according to the present invention is applied.

[Explanation of symbols]

 1 ... CCD image sensor 7 ... field memory 9 ... selection circuit 10, 12 ... pedestal control circuit 14 ... ..Microcomputer

Claims (3)

[Claims] 1. A solid-state image sensor for outputting an image-capturing signal of all pixels according to image-capturing light for each field period, and an image-capturing signal output from the solid-state image sensor for each field period as an image-capturing signal of a subject. And a black level image pickup signal, shutter means for controlling the image pickup signal output from the solid-state image pickup element, delaying means for delaying the image pickup signal output from the solid-state image pickup element by one field period, and outputting the signal. Based on the image pickup signal and the image pickup signal outputted from the solid-state image pickup device and delayed for one field period, the image pickup signal of the subject and the image pickup signal of the black level are selected, and based on the image pickup signal of the black level. A black balance adjusting means for adjusting the signal level of the image pickup signal, and an image pickup signal of a subject and an image pickup signal of a black level are obtained from the solid-state image pickup device every one field period. The solid-state imaging device characterized by comprising a control means for controlling said shutter means, for controlling said black balance adjustment means to adjust the signal level of an image signal as. 2. The shutter means is an electronic shutter for forcibly discarding the image pickup signal output from the solid-state image pickup device, and the control means sets the image pickup signal from the solid-state image pickup device to 1
2. The solid-state image pickup device according to claim 1, wherein the solid-state image pickup device controls the output of the image pickup signal of the subject and the image pickup signal of a black level by discarding the image pickup signals for each field. 3. The shutter means is a liquid crystal shutter that shields the imaging light incident on the solid-state imaging device, and the control means shields the imaging light incident on the solid-state imaging device for each field. The solid-state imaging device according to claim 1, wherein the solid-state imaging device controls the output of the imaging signal of the subject and the imaging signal of the black level.