JPH09130814A - Solid-state imaging device - Google Patents

Abstract

It is possible to perform white balance adjustment by adjusting a signal level of an image pickup signal even when an image of a subject having a high brightness enough to saturate the image pickup signal is taken. A CCD image sensor 1 outputs an image pickup signal based on a shutter operation of an electronic shutter. The switching circuit 12 selects the image pickup signal of the subject and the image pickup signal for white balance from the image pickup signal output from the CCD image sensor 1 and the image pickup signal delayed for one field period. The image signal for white balance is always adjusted to a constant signal level by the level adjusting circuit 16. The microcomputer 19 uses the image signal for white balance to adjust the white balance of the image signal of the subject.

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 having a white balance adjusting function for matching the signal levels of three primary color signals for an achromatic portion of a subject image.

[0002]

2. Description of the Related Art Generally, since the color temperature (spectral distribution characteristic) of a subject varies depending on the light source, when the solid-state imaging device photographs a white subject as it is, red (R), green (G),
The signal level of each of the blue (B) signals is different, and an image pickup signal with deteriorated color is output. Therefore, the solid-state imaging device performs white balance adjustment so that maximum color reproduction can be obtained at a specific color temperature. White balance adjustment
When a color temperature changes, a white subject is imaged and the signal level ratio of each color signal is corrected to be 1: 1: 1.

An example of a conventional solid-state image pickup device for adjusting white balance will be described below with reference to FIG.

As shown in FIG. 4, for example, this solid-state image pickup device includes a solid-state image pickup element 101 for outputting an image pickup signal, a correlated double sampling circuit 102, and a color separation circuit 103 for separating the image pickup signal into respective color signals. A difference detection circuit 104 and a difference detection circuit 106 that detect a difference in signal level;
A level adjusting circuit 105 and a level adjusting circuit 107 for adjusting a signal level, a so-called process circuit 108, an encoder 109, and a transmitting circuit 110 are provided.

In the solid-state image pickup device configured as described above, when a subject is imaged, the solid-state image pickup device 101 outputs an image pickup signal obtained from the image pickup light, and the image pickup signal is subjected to correlated double sampling (hereinafter , "CDS: Correrated Dou
ble sampling) circuit 102. CDS
The circuit 102 reduces random noise from the supplied image pickup signal and supplies the image pickup signal to the color separation circuit 103.

The color separation circuit 103 separates the supplied image pickup signal into R, G, and B color signals, supplies the R signal to the difference detection circuit 104 and the level adjustment circuit 105, and supplies the G signal to the difference detection circuit. 104, 106 and process circuit 108
To the difference detection circuit 106 and the level adjustment circuit 107.

The difference detection circuit 104 detects a difference in high luminance signal level from the supplied R signal and G signal, and controls the level adjustment circuit 105 so that the difference becomes zero. The level adjustment circuit 105 adjusts the signal level of the R signal based on the difference detection circuit 104 so that the signal level becomes a desired signal level, and the adjusted R signal is processed.
8

The difference detection circuit 106 detects a difference in high luminance signal level from the supplied B signal and G signal, and controls the level adjustment circuit 107 so that the difference becomes zero. The level adjustment circuit 107 adjusts the signal level of the B signal based on the difference detection circuit 106 so that the signal level becomes a desired signal level, and the adjusted B signal is processed.
8

The process circuit 108 receives the supplied R,
The G and B color signals are subjected to processes such as white clip for dynamic range compression, knee processing, blanking insertion, gamma correction, and black clip, and these color signals are supplied to the encoder 109.

The encoder 109 produces a composite color video signal from the supplied color signals and a composite sync signal supplied from a sync generation circuit (not shown) and supplies the composite color signal to the transmission circuit 110.

The transmission circuit 110 adjusts the signal level of the supplied color composite video signal so as to correspond to the standard of an image receiving device (not shown) to be transmitted, and then outputs the signal.

That is, this solid-state image pickup device detects the signal level of each color signal of high brightness while picking up an image of the subject even if the color temperature of the subject changes during the image pickup, and the signal levels are set to 1: 1: Since it can be corrected to 1, the white balance can always be adjusted.

[0013]

However, even with such a solid-state image pickup device, white balance adjustment cannot be performed depending on the object of the subject.

For example, in the case of picking up an image of a red object on the entire surface, the solid-state image pickup device cannot perform white balance adjustment because the object does not include white information. However, in this case, since it is natural that the white balance adjustment cannot be performed, it should be dealt with by prohibiting the white balance adjustment itself.

Further, when the solid-state image pickup device picks up an image of a low-brightness subject and an ultra-high-brightness white background such as spotlight, the CCD image sensor 1 outputs a saturated image pickup signal. The circuits 104 and 106 cannot detect the accurate difference between the color signals, and the white balance cannot be adjusted.

In particular, since green is the most abundant in nature, the CCD image sensor 1 saturates and outputs the G signal earliest, and as a result, the solid-state image pickup device can perform white balance adjustment. There wasn't.

The present invention has been made in view of such a situation, and even if an image of a subject having a high brightness enough to saturate the image pickup signal is picked up, white balance adjustment is performed by adjusting the signal level of the image pickup signal. An object of the present invention is to provide a solid-state image pickup device that outputs the image pickup signal.

[0018]

In order to solve the above-mentioned problems, a solid-state image pickup device 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. Signal processing for separating an imaging signal output from the solid-state imaging device into one frame signal output in one field period of the first or second field period and another frame signal output in the other one field period Means, white balance adjusting means for performing white balance adjustment for one frame signal, and white for controlling the white balance adjusting means by supplying a white balance control signal to the white balance adjusting means based on the other frame signals. Balance control means, shutter means for performing a shutter operation for varying the effective exposure amount of the solid-state image sensor, and other Based on the frame signal, and a shutter control means for controlling the shutter operation of the predetermined time period the shutter means to one field period apart.

Then, this solid-state image pickup device separates one frame signal and the other frame signal into an image pickup signal of a subject and an image pickup signal for white balance. Then, the solid-state image pickup device controls the shutter operation of the shutter means to adjust the effective exposure amount of the solid-state image pickup device, and sets the image signal for white balance to a constant signal level, so that the image pickup signal of the subject is changed. And stable white balance adjustment.

[0020]

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.

As shown in FIG. 1, the single plate type camera device 1 includes a CCD image sensor 10, a signal processing section 20, a white balance control section 40, a white balance adjustment section 50, and a shutter control section 60. Equipped with.

The image pickup signal output from the CCD image sensor 10 is, by the signal processing section 20, an image pickup signal of an object (hereinafter referred to as "image signal") and an image pickup signal for white balance (hereinafter referred to as "white balance signal"). ) And are separated. Then, the image signal is supplied to the white balance adjustment unit 50, while the white balance signal is supplied to the white balance control unit 40 via the shutter control unit 60. The white balance control unit 40 controls the white balance adjustment unit 50 based on the supplied white balance signal to adjust the white balance of the image signal. On the other hand, the shutter control unit 60
The shutter operation of the electronic shutter of the CCD image sensor 10 is controlled based on the white balance signal supplied from the signal processing unit 20.

Specifically, the CCD image sensor 10
When the image sensing light is received by the light receiving unit 11, each of the red, green, green, and blue time-division signal charges of all pixels in one field period is used as an imaging signal in the registers 12, 1.
2 lines are simultaneously output through the line 3. Further, the CCD image sensor 10 is provided with, for example, an electronic shutter, and this electronic shutter is 1H based on a shutter signal described later.
The shutter is closed during a field period in which the accumulated charge is discarded every cycle (one horizontal scanning cycle). This period is once every other field period, and the effective charge amount for white balance is variably controlled. Note that the shutter is open during the field periods other than the above period. As a result, the image pickup signal output from the CCD image sensor 10 is an image signal output when the electronic shutter is open for one field period and a white signal output when the electronic shutter is closed for one field period. It is composed of a white balance signal used for balance adjustment.

When the electronic shutter is opened, the CCD image sensor 10 outputs, for example, the image pickup signal of the pixel of the first field from the register 12, and at the same time, from the register 13 of the pixel of the second field. Output an image pickup signal. Here, the CCD image sensor 1
For 0, the fields to be read by the registers 12 and 13 are switched every time all pixels are read. The image pickup signal output from the CCD image sensor 10 in this manner is supplied to the signal processing unit 20 via the registers 12 and 13.

The signal processing unit 20, for example, a correlated double sampling circuit (hereinafter referred to as "CDS") 21 and a CDS circuit 25, an analog / digital (hereinafter referred to as "A / D") converter 26, a field memory 27, D. The A / A converter 28 and the switching circuit 29 are provided.

The CDS circuit 21 is supplied with the image pickup signal from the CCD image sensor 10, reduces the noise component contained therein, and then switches the image pickup signal consisting of the image signal and the white balance signal as shown in FIG. 2A. 29.

The CDS circuit 25 is supplied with the image pickup signal from the CCD image sensor 10, reduces noise components contained therein, and then supplies the image pickup signal to the A / D converter 26. The A / D converter 26 converts the image pickup signal into image pickup data and supplies the image pickup data to the field memory 27. The field memory 27 stores the image pickup data once and then reads the image pickup data,
Supply to the converter 28. Here, the field memory 27
Takes one field period from the storage of the image pickup data to the reading thereof. Therefore, the field memory 27 functions as a delay circuit that delays for one field period. The D / A converter 28 converts the supplied image pickup data into an image pickup signal and, as shown in FIG. 2B, sends an image pickup signal composed of an image signal delayed by one field period and a white balance signal to a switching circuit 29. Supply.

The switching circuit 29 includes terminals a and d connected to the CDS circuit 21, terminals b and c connected to the D / A converter 28, and a level adjusting circuit 61 of the shutter controller 60. And two switches 29a, 29b connected to the gain control circuit 30. When the switch 29a is at the terminal a, the switch 29b is at the terminal c, and when the switch 29a is at the terminal b, the switch 2 is provided.
9b is switched to the terminal d.

The switching circuit 29 includes switches 29a and 29 for each field period by a controller (not shown).
2b is performed, and the switch 29b is operated to switch the state shown in FIG.
The image signal as shown in FIG.
Outputs a white balance signal as shown in FIG. 2D.

Then, the switching circuit 29 supplies the image signal to the gain control circuit 30, and the gain control circuit 30 adjusts the signal level of the image signal and then supplies the image signal to the white balance adjusting section 50. At the same time, the switching circuit 29 sends the white balance signal to the white balance control unit 4 via the shutter control unit 60.
Supply 0.

The white balance control section 40 includes, for example, a color separation circuit 41 and a white balance control circuit 4.
2 and a microcomputer having sample hold function, A / D conversion function, and D / A conversion function (hereinafter referred to as "microcomputer").
43), and the white balance signal from the shutter controller 60 is supplied to the color separation circuit 41.

The color separation circuit 41 separates the supplied white balance signal into R, G, and B color signals, and supplies each color signal to the white balance control circuit 42. The white balance control circuit 42 adjusts the white balance of each of the supplied color signals based on a control signal from the microcomputer 43 described later. Then, the white balance control circuit 42 supplies the adjusted color signals to the microcomputer 43. The microcomputer 43 samples a high-brightness signal level of a certain level or higher from each of the supplied color signals and detects, for example, the difference between the signal levels of the R signal and the G signal. Then, the microcomputer 43 supplies an R control signal for controlling the R signal so that the difference becomes zero to the white balance control circuit 42, and also supplies the same R control signal to the white balance adjusting unit 50. Further, the microcomputer 43 similarly supplies the B control signal for controlling the B signal to the white balance control circuit 42, and also supplies the same B control signal to the white balance adjusting unit 50.

The white balance adjusting section 50 includes, for example, a color separation circuit 51 and a white balance control circuit 52 having the same circuit characteristics as the above-mentioned white balance control circuit 42, and the color separation circuit 51 displays an image from the gain control circuit 30. Signal is supplied.

The color separation circuit 51 separates the supplied image signal into R, G and B color signals. Then, the color separation circuit 5
1 is a white balance control circuit 5 for each color signal
Feed to 2. White balance control circuit 52
Is based on the R control signal supplied from the microcomputer 43,
The R signal is controlled so that the G signal and the R signal have the same signal level, and similarly, the B signal is controlled based on the B control signal so that the G signal and the B signal have the same signal level.

As a result, the microcomputer 43 can adjust the white balance via the white balance control circuit 52 so that the signal level ratios of the respective color signals in the image signal become equal.

White balance control circuit 52
Supplies the color signals whose white balance has been adjusted in this way to the process circuit 71.

The process circuit 71 receives the supplied R, G,
The color signals of B are subjected to white clip for dynamic range compression, knee processing, blanking insertion, gamma correction, black clip, and the like, and these color signals are supplied to the encoder 72. The encoder 72 produces a composite color video signal from the supplied color signals and a composite sync signal supplied from a sync generation circuit (not shown),
This composite color image is supplied to the transmission circuit 73. The transmission circuit 73 adjusts the signal level of the supplied color video signal so that the supplied color composite video signal corresponds to the standard of an image receiving device (not shown) to be transmitted, and then outputs the color composite video signal.

On the other hand, the shutter controller 60 is supplied with the white balance signal from the signal processor 20, as described above.

The shutter control section 60 includes, for example, a level adjusting circuit 61, a peak rectifying circuit 62, and a difference detecting circuit 6
3 and a difference detection circuit 64, a NAND element 65, and an amplitude conversion circuit 66, and a white balance signal is supplied to the level adjustment circuit 61.

The level adjusting circuit 61 adjusts the supplied white balance signal according to the output of the difference detecting circuit 63, which will be described later, and supplies the adjusted white balance signal to the peak rectifying circuit 62, while In addition, the white balance control unit 40 is also supplied. Peak rectifier circuit 6
2 rectifies the white balance signal into a DC signal having the same value as the peak value, and supplies the DC signal to the difference detection circuit 63, as shown by the dotted line in FIG. 2E.

The difference detection circuit 63 is a peak rectification circuit 62.
The difference between the DC signal supplied from the controller and the DC signal V _Z having a constant value is detected, and the obtained DC signal is supplied to the difference detection circuit 64 and the level adjustment circuit 61.

At this time, the level adjusting circuit 61 adjusts and outputs the signal level of the white balance signal supplied from the switching circuit 29 so that the signal level from the difference detecting circuit 63 becomes a desired signal level. As a result, the level adjustment circuit 61 can output a white balance signal that is always suitable for white balance adjustment and has a constant peak value by a closed loop from the difference detection circuit 63 to the level adjustment circuit 61. In other words, the level adjustment circuit 61 receives the image signal of high brightness enough to saturate, and conversely, the image signal of low brightness insufficient to adjust the white balance, The white balance signal can be set to a signal level suitable for the adjustment, and as a result, the white balance control unit 40 and the white balance adjustment unit can always perform stable white balance adjustment.

The stable DC signal from the difference detecting circuit 63 is supplied to the difference detecting circuit 64.

The difference detection circuit 64 is a comparator that outputs "1" when the comparison signal is larger than the reference signal and outputs "0" when the comparison signal is smaller than the reference signal. A DC signal is supplied from the circuit 63, and a sawtooth wave shown in FIG. 2E is supplied as a comparison signal. Then, as shown in FIG. 2F, the difference detection circuit 64 outputs a square wave having a period of two field periods as one cycle, and supplies this to the NAND element 65.

The NAND element 65 is supplied with the square wave from the difference detection circuit 64 and a pulse signal having the same period as the 1H period of the CCD image sensor 10 as shown in FIG. 2G. Then, the NAND element 65 outputs their NAND and supplies a shutter signal for controlling the shutter operation of the electronic shutter to the amplitude conversion circuit 66, as shown in FIG. 2H. The amplitude conversion circuit 66 converts the amplitude of the shutter signal into a predetermined signal level and converts the shutter signal into a CC signal.
It is supplied to the substrate of the D image sensor 10. The electronic shutter forcibly discards the image pickup signal output from the CCD image sensor 10 and closes the shutter while the shutter signal of a predetermined signal level is supplied.

Here, since the NAND element 65 to the CCD image sensor 10 form a closed loop, NA
The ND element 65 outputs a shutter signal according to the signal level of the image pickup signal from the CCD image sensor 10.

For example, when the single-plate type camera device 1 picks up an image of a high-luminance subject, a white balance signal having a high signal level is obtained in the switching circuit 29, and the signal is passed through the level adjusting circuit 61 and the peak rectifying circuit 62. A high-level DC signal is supplied to the difference detection circuit 63. Then, the difference detection circuit 63 detects a DC signal having a low signal level, the difference detection circuit 64 detects a pulse signal having a wide pulse width, and the NAND element 65 outputs a shutter signal that makes the closing period of the electronic shutter longer. To do. That is,
The electronic shutter is designed to narrow the exposure so as to obtain an appropriate white balance signal by prolonging the shutter closing period when a high-brightness subject is imaged. In other words, the single-panel camera device 1 obtains an appropriate white balance signal even when capturing a high-luminance subject,
White balance can be adjusted. Conversely, the single-chip camera device 1 can also obtain an appropriate white balance signal and perform white balance adjustment even when an image of a low-luminance subject is captured.

As described above, this single plate type camera device 1
Is an image of a subject that is saturated enough to be saturated, on the contrary,
Even if an image of a low-brightness subject is imaged, an image pickup signal with high image quality can be output by performing an appropriate white balance adjustment.

The single-chip type camera device 1 is, for example, a CDS circuit 2 so that a still image can be captured.
For example, an image memory may be inserted between 1 and the switching circuit 29.

Next, the second solid-state image pickup device according to the present invention will be described.
An embodiment will be described with reference to the drawings.

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

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 in each circuit of each color signal, only the operation of the G signal will be described, and the operation of other color signals will be omitted.

This three-plate type camera device 80 is shown in FIG.
As shown in FIG. 5, CCD image sensors 10R, 10G and 10B arranged corresponding to the imaging lights converted into the three primary color lights of R, G and B, and the signal processing units 20R and 20.
G, 20B, a white balance control unit 40, a white balance adjustment unit 50, and a shutter control unit 60.

CCD image sensor 10R, 10G, 1
The color signal output from 0B is output to the signal processing units 20R and 20R.
By G and 20B, separation processing is performed into a color signal of the subject (hereinafter referred to as "image color signal") and a color signal for white balance (hereinafter referred to as "white balance color signal") by G and 20B. Then, each image color signal is supplied to the white balance adjustment unit 50, while each white balance color signal is supplied to the white balance control unit 40 via the shutter control unit 60 and the like. White balance control unit 4
0 controls the white balance adjusting unit 50 based on the supplied white balance color signal to adjust the white balance of the image color signal. On the other hand, the shutter control unit 60
Based on the white balance color signal supplied from the signal processing unit 20G, the CCD image sensors 10R, 10G, 1
Controls the shutter operation of the 0B electronic shutter.

Specifically, the CCD image sensor 10G
When the image sensing light is received by the light receiving portion 11G, the green (G) signal charges of all pixels are used as color signals in one field period,
Two lines are simultaneously output via the registers 12G and 13G. Further, the CCD image sensor 10G includes, for example, an electronic shutter, and the electronic shutter is closed during a field period in which the accumulated charge is discarded every 1H period (1 horizontal scanning period) based on a shutter signal described later. It has become. This period is 1 every 1 field period
The number of effective charges for white balance is variably controlled. Note that the shutter is open during the field periods other than the above period. As a result, the CCD image sensor 1
The color signal output from 0G is an image color signal output when the electronic shutter is open during one field period, and is output when the electronic shutter is closed during one field period for white balance adjustment. It consists of the white balance color signal used.

Then, the CCD image sensor 10G is
When the electronic shutter is open, for example, the register 12
The color signal of the pixel of the first field is output from G, and at the same time, the color signal of the pixel of the second field is output from the register 13G, for example. Here, the CCD image sensor 1
With 0G, the fields to be read by the registers 12G and 13G are switched every time all pixels are read. In this way, the CCD image sensor 10G
The color signal output from is supplied to the signal processing unit 20G via the registers 12G and 13G.

The signal processing unit 20G is, for example, the CDS circuit 2
1G and CDS circuit 25G, A / D converter 22G and A / D converter 26G, field memory 23G and field memory 27G, D / A converter 24G and D /
An A converter 28G and a switching circuit 29G are provided.

The CDS circuit 21G is supplied with the color signal from the CCD image sensor 10G to reduce the noise component contained therein, and then the color signal is subjected to the A / D converter 22G.
To supply. The A / D converter 22G converts the color signal into color data and supplies the color data to the field memory 23G. The field memory 23G stores the color data once and then reads the color data, and supplies the color data to the D / A converter 24G.
Here, the field memory 23G can store and read G data without delay and can capture, for example, a still image. The D / A converter 24G converts the color data supplied from the field memory 23G into a color signal,
As shown in FIG. 2A, a color signal including an image color signal and a white balance color signal is supplied to the switching circuit 29G.

On the other hand, the CDS circuit 25G is supplied with the color signal from the CCD image sensor 10G to reduce the noise component contained therein, and then the color signal is subjected to the A / D converter 2
Supply to 6G. The A / D converter 26G converts the color signal into color data and supplies the color data to the field memory 27G. The field memory 27G stores the color data once and then reads the color data, and supplies the color data to the D / A converter 28G. Here, the field memory 27G takes one field period from the storage of the color data to the reading thereof. Therefore, the field memory 27G has 1
It has the same function as a delay circuit that delays the field period. The D / A converter 28G converts the supplied color data into a color signal and, as shown in FIG. 2B, switches the color signal composed of the image color signal delayed by one field period and the white balance color signal to the switching circuit. Supply to 29G.

The switching circuit 29G includes the terminals a and d connected to the A / D converter 24G and the D / A converter 28.
Two switches 29Ga and 29 connected to the terminal b and terminal c connected to G, and the level adjustment circuit 61G and the gain control circuit 30G of the shutter control unit 60.
Gb is provided, and when the switch 29Ga is at the terminal a, the switch 29Gb is at the terminal c and the switch 29Ga is at the terminal b.
When the switch is on, the switch 29Gb is switched to the terminal d.

In the switching circuit 29G, the switches 29Ga and 29Gb are switched by the controller (not shown) every one field period, the switch 29Gb outputs the image color signal as shown in FIG. 2C, and the switch 29Ga outputs it. Outputs a white balance color signal as shown in FIG. 2D.

Then, the switching circuit 29G supplies the image color signal to the gain control circuit 30G, and the gain control circuit 30G adjusts the signal level of the image color signal and then supplies the image color signal to the white balance adjusting section 50. Supply. Further, the switching circuit 29G simultaneously supplies the white balance color signal to the white balance control unit 40 via the shutter control unit 60.

The switching circuits 29R and 29B similarly supply the image color signals to the white balance adjusting section 50. For the white balance color signals, the white balance controlling sections 61R and 61B are used. Supply to 40.

The white balance control section 40 is provided with, for example, a white balance control circuit 42 and a microcomputer 43 having the functions of sample hold, A / D conversion, and D / A conversion.
2 are supplied with R, G, and B white balance color signals.

White balance control circuit 42
Adjusts the white balance of each of the supplied white balance color signals based on a control signal from the microcomputer 43 described later. Then, the white balance control circuit 42 supplies the adjusted white balance color signal to the microcomputer 43. The microcomputer 43 samples a high-brightness signal level of a certain level or higher from each of the supplied white balance color signals, and detects, for example, the difference between the signal levels of the R signal and the G signal. Then, the microcomputer 43
Supplies an R control signal for controlling the R signal so that the difference becomes zero to the white balance control circuit 42, and also supplies the same R control signal to the white balance adjusting section 50. Further, the microcomputer 43 similarly supplies the B control signal for controlling the B signal to the white balance control circuit 42, and also supplies the same B control signal to the white balance adjusting unit 50.

The white balance adjusting section 50 is provided with a white balance control circuit 52 having the same circuit characteristics as the above-mentioned white balance control circuit 42, and image color signals are supplied from the gain control circuits 30R, G, B, respectively. The white balance control circuit 52 controls the R signal based on the R control signal supplied from the microcomputer 43 so that the G signal and the R signal have the same signal level, and similarly, based on the B control signal, the G signal. The B signal is controlled so that the signal levels of the B signal and the B signal are the same.

As a result, the microcomputer 43 can adjust the white balance via the white balance control circuit 52 so that the signal level ratios of the R, G, and B image color signals become equal.

White balance control circuit 52
Supplies the image color signals thus white-balance adjusted to the process circuit 71.

The process circuit 71 receives the supplied R, G,
The image color signal of B is subjected to processing such as white clip for dynamic range compression, knee processing, blanking insertion, gamma correction, and black clip, and each color signal of these images is supplied to the encoder 72. Encoder 72
Generates a composite color video signal from each of the supplied image color signals and a composite sync signal or the like supplied from a sync generation circuit (not shown), and supplies this composite color video to the transmission circuit 73. The transmission circuit 73 adjusts the signal level of the supplied color video signal so that the supplied color composite video signal corresponds to the standard of an image receiving device (not shown) to be transmitted, and then outputs the color composite video signal.

On the other hand, the shutter controller 60 is supplied with the white balance color signal from the signal processor 20G as described above.

The shutter control section 60 includes, for example, a level adjusting circuit 61G, a peak rectifying circuit 62, a difference detecting circuit 63 and a difference detecting circuit 64, a NAND element 65, and an amplitude converting circuit 66, and the level adjusting circuit. A white balance color signal is supplied to 61G.

The level adjusting circuit 61G adjusts the supplied white balance color signal according to the output of the difference detecting circuit 63 described later, and supplies the adjusted white balance color signal to the peak rectifying circuit 62, while like,
It is also supplied to the white balance adjustment unit 40. As shown by the dotted line in FIG. 2E, the peak rectifier circuit 62 rectifies the white balance color signal into a DC signal having the same value as its peak value, and supplies the DC signal to the difference detection circuit 63.

The difference detection circuit 63 is a peak rectification circuit 62.
The difference between the DC signal supplied from the controller and the DC signal V _Z having a constant value is detected, and the obtained DC signal is supplied to the difference detection circuit 64 and the level adjustment circuit 61.

At this time, the level adjusting circuit 61G adjusts and outputs the signal level of the white balance color signal supplied from the switching circuit 29G so that the signal level from the difference detecting circuit 63 becomes a desired signal level. As a result,
The level adjustment circuit 61G can output a white balance color signal that is always suitable for white balance adjustment and has a constant peak value by a closed loop from the difference detection circuit 63 to the level adjustment circuit 61G. That is,
The level adjusting circuit 61G receives a color signal having a high brightness enough to saturate, or conversely, a color signal having a low brightness insufficient to achieve white balance adjustment,
The white balance color signal can be set to a signal level suitable for the adjustment, and as a result, the white balance control unit 40 and the white balance adjustment unit 40 can always perform stable white balance adjustment.

Then, the stable DC signal from the difference detection circuit 63 is supplied to the difference detection circuit 64.

The difference detection circuit 64 is a comparator that outputs "1" when the comparison signal is larger than the reference signal and outputs "0" when the comparison signal is smaller than the reference signal. A DC signal is supplied from the circuit 63, and a sawtooth wave shown in FIG. 2E is supplied as a comparison signal. Then, as shown in FIG. 2F, the difference detection circuit 64 outputs a square wave having a period of two field periods as one cycle, and supplies this to the NAND element 65.

The NAND element 65 is supplied with the square wave from the difference detection circuit 64 and a pulse signal having the same period as the H period (1 horizontal scanning period) of the CCD image sensor 10 as shown in FIG. 2G. Then, the NAND element 65 is
As shown in FIG. 2H, by outputting the NAND of them,
A shutter signal that controls the shutter operation of the electronic shutter is supplied to the amplitude conversion circuit 66. The amplitude conversion circuit 66 converts the amplitude of the shutter signal into a predetermined signal level and supplies the shutter signal to the substrate of the CCD image sensor 10G. The electronic shutter forcibly discards the color signal output from the CCD image sensor 10G and closes the shutter while the shutter signal having a predetermined signal level is supplied.

Since a closed loop is formed from the NAND element 65 to the CCD image sensor 10G, N
The AND element 65 outputs the shutter signal according to the signal level of the image pickup signal from the CCD image sensor 10G.

For example, when the three-plate type camera device 80 images a high-luminance subject, a white balance color signal with a high signal level is obtained in the switching circuit 29G, and the white balance color signal is passed through the level adjusting circuit 61G and the peak rectifying circuit 62. A DC signal having a high signal level is supplied to the difference detection circuit 63. Then, the difference detection circuit 63 detects a DC signal having a low signal level, the difference detection circuit 64 detects a pulse signal having a wide pulse width, and the NAND element 65 outputs a shutter signal that makes the closing period of the electronic shutter longer. To do. That is, the electronic shutter is adapted to narrow the exposure so as to obtain an appropriate white balance color signal by prolonging the shutter closing period when a high-brightness subject is imaged. In other words, the three-plate type camera device 80 is
Even if a high-luminance subject is imaged, or conversely, a low-luminance subject is imaged, an appropriate white balance color signal can be obtained and white balance adjustment can be performed.

As described above, the three-plate type camera device 80
Is an image of a subject that is saturated enough to be saturated, on the contrary,
Even if an image of a low-brightness subject is imaged, an image pickup signal with high image quality can be output by performing an appropriate white balance adjustment.

Further, the three-plate type camera device 80 separates the image pickup light into R, G, B color signals and forms respective images on the photosensitive surfaces of the CCD image sensors 1R, 1G, 1B. Basically, the imaging light can be used without loss, the SN ratio is good, high resolution is obtained, and the color filter characteristics are independently determined, so that an image pickup signal with good color reproduction can be obtained. You can

Further, the above-described first embodiment and second embodiment
In the embodiment, the electronic shutter is applied as the shutter means of the solid-state imaging device, but a liquid crystal shutter may be used instead of the electronic shutter.

Although the solid-state image pickup device has been described by using the case of auto white balance in the above-mentioned embodiments, it is needless to say that it can be applied to the case of so-called one-push type white balance.

[0085]

As described in detail above, in the solid-state image pickup device according to the present invention, the image pickup signal output from the solid-state image pickup device and the image pickup signal output from the solid-state image pickup device and delayed by one field period are provided. From the image pickup signal of the subject and the image pickup signal for white balance. Since the image signal for white balance is constantly adjusted regardless of the signal level of the image signal, the white balance of the image signal can be adjusted. That is, this solid-state image pickup device outputs an image pickup signal with a good image quality with white balance adjustment, even if an image of a subject having a high brightness enough to be saturated is taken under a light source having a color temperature of 2000 to 9000 ° K. You can

[Brief description of the drawings]

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

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

FIG. 3 is a block diagram for explaining adjustment of black balance 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]

 10 CCD image sensor 20 signal processing unit 40 white balance control unit 50 white balance adjustment unit 60 shutter control unit

Claims (3)

[Claims] 1. A solid-state image sensor for outputting an image-capturing signal of all pixels corresponding to image-capturing light for each field period, and an image-capturing signal output by the solid-state image sensor for the first or second
A signal processing unit that separates and processes one frame signal output in one field period of the field period and another frame signal output in the other one field period, and white for performing white balance adjustment on the one frame signal. A white balance control means for controlling the white balance adjusting means by supplying a white balance control signal to the white balance adjusting means based on the other frame signal; A solid-state device comprising: shutter means for performing a shutter operation for varying an exposure amount; and shutter control means for controlling the shutter operation of the shutter means for a predetermined period every one field period based on the other frame signal. Imaging device. 2. The shutter means is an electronic shutter for forcibly discarding the image pickup signal output from the solid-state image pickup element, and the shutter control means discards the image pickup signal from the solid-state image pickup element for a predetermined time. The solid-state image pickup device according to claim 1, wherein the solid-state image pickup device is read out and controlled. 3. The shutter means is a liquid crystal shutter that shields the imaging light incident on the solid-state imaging device, and the shutter control means shields the imaging light incident on the solid-state imaging device at predetermined time intervals. The solid-state imaging device according to claim 1, wherein the liquid crystal shutter is controlled thereby.