JP2580560B2 - Solid color imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a so-called picture in which a solid-state imaging device of a predetermined color is spatially shifted by a half pixel pitch with respect to another solid-state imaging device. The present invention relates to a solid-state color imaging device to which a shift imaging method is applied.

[Summary of the Invention]

The present invention relates to a solid-state color imaging device to which a pixel shift imaging method is applied, wherein a difference between a reference level and a signal level is determined for an output signal of each solid-state imaging device including a repetition of a reference level section and a signal level section. By obtaining an image pickup signal from which noise has been removed by taking a predetermined color signal, a predetermined color signal is passed through a sample hold circuit capable of adjusting the sample timing, and the delay amount of a subsequent circuit that performs contour compensation using the predetermined color signal is calculated. By absorbing the difference by the sample and hold circuit, it is possible to perform contour compensation without deteriorating the effect of the picture element shifting imaging method.

[Conventional technology]

In a solid-state color imaging device, for example, a CCD (Charg
e Coupled Device) Image sensor for other red and blue
2. Description of the Related Art A picture element shift imaging method in which a CCD image sensor is horizontally shifted by a half picture element pitch is often used.
According to this, for example, the resolution of the imaging device can be improved without increasing the number of elements corresponding to the pixels of the CCD.

When arranging the solid-state imaging devices at a half pixel pitch, it is necessary to mechanically adjust the three solid-state imaging devices with high precision.

In addition, regarding signal processing for output signals of the solid-state imaging devices, it is necessary to minimize delay errors of carrier-balanced color signals.

By the way, usually, in an imaging device, a contour compensation process is performed on an imaging signal. This processing is often performed mainly using the green signal, utilizing the property that the rate at which the green signal contributes to the luminance is high. The contour compensating circuit includes a delay element having one horizontal cycle.

[Problems to be solved by the invention]

Since the contour compensation circuit includes a delay element having one horizontal cycle, the delay amount of each color signal in the signal processing unit varies. Due to this variation, even if the above-described mechanical alignment of the solid-state imaging devices is highly accurate, the effect of the carrier balance is reduced. That is, in the conventional solid-state color image pickup device, there is a problem that when the contour compensation is performed by the contour compensation circuit, the improvement of the resolution which is the effect of the picture element shift imaging method is adversely affected.

Further, since the signal itself obtained from the CCD image pickup device is a signal including noise due to the internal device noise or the influence of the driving pulse, it is necessary to remove these noises.

The present invention has been made in view of such a problem, and obtains an imaging signal from which noise has been removed, and removes the above-described variation in the amount of delay, thereby maintaining the improvement in resolution by the pixel shift imaging method. An object of the present invention is to provide a solid-state color imaging device capable of performing contour compensation.

[Means for solving the problem]

In order to achieve the above object, in the present invention, a solid-state imaging device of a predetermined color is spatially shifted by a half pixel pitch with respect to other solid-state imaging devices, and a solid-state imaging device of a predetermined color is arranged. A solid-state color imaging device of a multi-plate type in which a contour compensation signal is formed from an imaging output signal of the solid-state imaging device, and contour compensation is performed on an imaging output signal of each solid-state imaging device by adding the contour compensation signal. The difference between the reference level and the signal level of the charge detection signal which repeats a reference level portion for each bit of the output of the element and a signal portion charged or discharged according to the output charge from the reference level is calculated. A charge detection circuit that outputs an image pickup output signal of each solid-state image pickup device; and an image pickup output signal of the solid-state image pickup device of the predetermined color supplied from the charge detection circuit, which is supplied to a predetermined sampling pulse. A sample and hold circuit for sampling and holding, a contour compensation circuit for forming a contour compensation signal from an imaging output signal of the solid-state imaging device of the predetermined color supplied via the sample and hold circuit, and the charge detection circuit And an adder for adding the contour compensation signal formed by the contour compensation circuit to the imaging output signal of the solid-state imaging device of the predetermined color supplied through the contour compensation circuit, and supplied from the charge detection circuit. An adder that adds the contour compensation signal formed by the contour compensation circuit to the imaging output signal of the solid-state imaging device of the other color; and a variable delay circuit that delays a predetermined sampling pulse supplied to the sample and hold circuit. An imaging output signal of a solid-state imaging device of a predetermined color supplied to the adder via the contour compensation circuit; and the charge detection circuit. The delay amount of the variable delay circuit is set to a delay amount in consideration of a relative delay with respect to an imaging output signal of the other color solid-state imaging device supplied to the adder, and the sampling is performed with the delay amount. A sample and hold circuit is operated.

[Action]

In the solid-state color imaging device according to the present invention, the difference between the reference level and the signal level is extracted from the output signal from the solid-state imaging device, which is a repetition of the reference level section and the signal section, by the charge detection circuit.

Further, an imaging output signal of the solid-state imaging device of a predetermined color supplied to the adder via the contour compensation circuit and an imaging of the solid-state imaging device of another color supplied to the addition device from the charge detection circuit. The sample-and-hold circuit is controlled by a sampling pulse passing through the variable delay circuit in which a delay amount is set in consideration of a relative delay with an output signal,
Sampling is performed.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment in which the present invention is applied to a solid-state color image pickup device using three CCDs.

A so-called 1/2 picture element shifted imaging method is applied to the arrangement of the CCD imaging elements 1G, 1R, and 1B. That is, for red and blue
In the CCD image sensors 1R and 1B, the corresponding picture elements occupy the same spatial position, and the CCD image sensor 1G for green has a half picture element pitch in the horizontal direction with respect to the CCD image sensors 1R and 1B. They are only shifted. In addition, the CCD image sensor 1G
Are arranged vertically displaced from the CCD image pickup devices 1R and 1B by one picture element. As a result, the above CCD
The output signal of the image sensor 1G has a one-horizontal periodic phase advanced from the output signals of the CCD image sensors 1R and 1B.
This advance of the phase is absorbed in the contour compensation circuit at the subsequent stage.

The CCD image sensors 1G, 1R, 1B are driven by a plurality of drive pulses supplied by the timing generator 3,
The signal is sent to each charge detection circuit, CDS (Corelated Doubl).
e Sampling) Output to circuits 2G, 2R, 2B. In the CDS circuit, the input signal is sampled twice by two sampling pulses SP1 and SP2 supplied from the timing generator 3 to remove noise and output a stepped image signal. Details of the CDS circuits 2G, 2R, 2B will be described later.

The output signal of the green CDS circuit 2G is supplied to the sample and hold circuit 4. The sampling pulse SP3 of the sample hold circuit 4 is supplied from the timing generator 3 via the variable delay circuit 5. The sample-and-hold circuit 4 cancels out the horizontal 1/2 pixel pitch shift of the green signal output from the CDS circuit 2G.

The output signal of the sample and hold circuit 4 passes through a trap filter 6G for removing clock components and the like and an amplifier 7G.
It is supplied to the contour compensation circuit 8. The rear contour compensating circuit 8 is composed of delay circuits 8a and 8b of one horizontal cycle for a green signal, a signal processing circuit 8c, and the like. The output signal of the amplifier 7G and this output signal are output by the one horizontal cycle delay circuit 8b. The contour compensation signal SIE is output based on the signal delayed by the horizontal cycle, the signal further delayed by one horizontal cycle by the one horizontal cycle delay circuit 8a, and the red signal that has passed through the trap filter 6R and the amplifier 7R.

The contour compensation signal SIE is added to the green signal passed through the one horizontal period delay circuit 8b in an adder 9G. The output signal of the addition circuit becomes a green signal subjected to contour compensation,
It is supplied to a γ (gamma) correction circuit 10G.

In addition, the contour compensation signal SIE is added to the red signal output from the amplifier 7R in the adding circuit 9R, and the red signal subjected to contour compensation by the adding circuit 9R is added to the γ correction circuit.
Supplied to 10R.

In addition, in the addition circuit 9B, the blue signal that has passed through the trap filter 6B and the amplifier 7B is added to the contour compensation signal SIE, and the contour-compensated blue signal is supplied to the γ correction circuit 10B.

Output signals of the γ correction circuits 10G, 10R, and 10B are supplied to a luminance signal matrix circuit 11 and a color signal matrix circuit 12. A luminance signal obtained from the luminance signal matrix circuit 11 and a color signal obtained from the color signal matrix circuit 12 are combined with a television signal by an encoder 13, and a composite video signal is output to an output terminal 14.

Next, the configuration and operation of the CDS circuits 2G, 2R, 2B will be described. Since the three CDS circuits 2G, 2R, and 2B have the same configuration and are simultaneously driven by the sampling clocks SP1 and SP2, the CDS circuit 2G for a green signal will be described here.

The CDS circuit 2G, as shown in FIG. 2, three sample-and-hold circuits 20a, 20b, and 20c, is composed of a differential amplifier 20d, the CCD image sensor output signal V ₀ from 1G is supplied,
The sampling pulse SP1, SP2 is supplied from the timing generator 3.

The relationship between the output signal V ₀ and the sampling pulse SP1, SP2 shown in the timing chart of FIG. 3. The output signal V ₀ is output from the CCD by the timing generator 3.
The control of the imaging device 1G, the level becomes a repetition signal of the period tau _B consisting period T _s of the precharge period T _p and the signal level is E _r. The sample hold circuit 20a, the sampling pulse SP1 supplied to 20c, rather than the front edge of the precharge period of the output signal V ₀ delayed by τ _{d =} τ _B -T _P, the pulse width is equal to T _p. The above sample hold circuit 20a signal level portion of the output signal V ₀ is sampled and held, the differential amplifier whose hold output H _s
It is supplied to the inverting input terminal of 20d.

Further, the output signal V ₀ is applied to the sample and hold circuit 20.
Also supplied to b. The Sample-and-hold circuit 20b, is supplied with the sampling pulse SP2 as a high level during the precharge period T _p of the output signal V _0, a precharge period T _p level E _r is sampled and held its hold output H _N1 of Is supplied to the sample hold circuit 20c. The hold output H _N1 is sampled and held in the sample and hold circuit 20c by the sampling pulse SP1, and the hold output H _N2 is supplied to the non-inverting input terminal of the differential amplifier 20d.

Here, the output signal H _S shown in FIG. 3, H _N1, H _N2, pulse voltage E _P 'is in the sampling pulses SP1 and SP2 are sample hold circuits 20a, 20b, FET in 20c (Field Effect T
This is the amount of the jump pulse generated by jumping into the output signal through a gate-source capacitance such as a rans-istor.

By the way, the output signal H of the sample and hold circuit 20a
_S is the signal level period of the output signal V ₀ which from the CCD image sensor 1G
Since it is a sample value of T _S , it is a signal component + a noise component. On the other hand, the output signal H of the sample-and-hold circuit 20b
_N1 is not the signal component from a sample value of the precharge period T _P of the output signal V _0, only the noise component.
Therefore, the noise component can be removed by taking the difference between the two output signals H _S and H _N1 . However, since the two output signals H _S and H _N1 are sample-and-hold outputs at different points in time of the output signal V _0, a phase difference is generated between the points at which the diving pulse is output, as is apparent from FIG. Therefore, if the difference between the two output signals H _S and H _N1 is taken, a dive pulse will appear as it is.In this circuit, the output signal H _N1 is further sampled and held by the sample and hold circuit 20c. Hold output signal H _N2
Jump pulses appearing at will therewith synchronization of the output signal H _S. As a result, as the output of the differential amplifier 20d, a signal is obtained in which the noise component is removed and the jump pulse during the sample hold is sufficiently suppressed. Thus, an imaging signal from which noise has been removed is obtained at the outputs of the CDS circuits 2G, 2R, and 2B.

The CCD image sensors 1G, 1R, and 1B are commonly driven by the timing generator 3. Further, as described above, the CCD image sensor 1G is connected to the CCD image sensors 1R and 1R.
B is shifted horizontally by 1/2 picture element pitch. Therefore, the output signal of the CDS circuit 2G and the output signal of the CDS circuits 2R and 2B are shifted in phase by an amount corresponding to a half picture element pitch. The sample hold circuit 4 is used to eliminate this phase shift.

Also, in order to maintain the effect of the pixel shift imaging method,
For example, at the input of the luminance signal matrix circuit 11,
The delay amounts of the green, red, and blue signals need to match. However, the red and blue signals are output from the respective amplifiers 7R and 7R.
While the output signal of B is directly supplied to each of the adders 9R and 9B, the green signal passes through the amplifier 7G and then passes through the one-horizontal-cycle delay element 8b of the contour compensation circuit 8. It is supplied to the addition circuit 9G.

As described above, since the CCD image sensor 1G for green is arranged to be shifted by one picture element in the vertical direction as compared with the other CCD image sensors 1R and 1B, the green signal is advanced by one horizontal period phase. It has become something. The green signal is the one horizontal period delay element 8b
As a result, the phase is delayed by one horizontal cycle, so that the green, red, and blue signals have the same phase at the input of the luminance signal matrix circuit 11. However, due to the accuracy or characteristic fluctuation of the delay element 8b of one horizontal cycle, the delay time of the green signal varies, and a phase difference occurs between the green signal and the red and blue signals.

This variation in delay time is absorbed by adjusting the sample timing of the sample and hold circuit 4. That is, the sampling pulse SP3 output from the timing generator 3 is supplied to the sample and hold circuit 4 via the variable delay circuit 5. The variable delay circuit 5 includes, for example, the luminance signal matrix circuit 11 described above.
, The green, red, and blue signals are observed, and the adjustment is performed so that the difference in the amount of delay between the green signal and the red and blue signals is eliminated. As a result, the phases of the respective signals match, and the effect of the picture element shifting imaging method is maintained. Also, contour compensation is performed normally.

The variable delay circuit 5 uses, for example, a glass delay line. At this time, it is more preferable to adjust the glass delay line in consideration of the temperature characteristic of the delay.

In the present embodiment, the sample-and-hold circuit 4 is connected to the output of the CDS circuit 2G to obtain an image signal whose delay amount has been adjusted. For example, as shown in the block diagram of FIG. May be integrated to form a CDS circuit capable of delay adjustment.

In this circuit, the outputs of the sample and hold circuits 40a and 40c controlled by the sampling pulse SP1 are supplied to the differential amplifier 40f via the sample and hold circuits 40d and 40e. The sample and hold circuits 40d and 40e are controlled by the sampling pulse SP3 passing through the variable delay circuit 5. Therefore, the sample-and-hold signals H _D1 and H _D2 supplied to the differential sump 40f have been subjected to the adjustment of the delay amount, and the output of the differential amplifier 40f has noise removed and the delay amount has been adjusted. The obtained imaging signal is obtained.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain an imaging signal from which noise has been removed. Further, since the difference between the delay amounts of the respective color signals can be removed by adjusting the delay amount of the predetermined color signal, the operation of the contour compensation circuit does not reduce the effect of the 1/2 picture element shift imaging method. . Therefore, it is possible to provide a solid-state color imaging device capable of obtaining a clear image with improved resolution.

[Brief description of the drawings]

FIG. 1 is a block diagram of the present embodiment in which the present invention is applied to a solid-state color imaging device using three CCDs. FIG. 2 is a block diagram of the CDS circuit used in the present embodiment, and FIG. 3 is a timing chart for explaining the operation of the CDS circuit. FIG. 4 is a block diagram of a CDS circuit capable of delay adjustment in which a CDS circuit and a circuit for delay adjustment are integrated. 1G, 1R, 1B CCD image sensor 2G, 2R, 2B CDS circuit 3 Timing generator 4 Sample hold circuit 5 Variable delay circuit 8 Contour compensation circuit 8a, 8b 1H delay element 9G, 9R, 9B Addition circuit 10G, 10R, 10B Gamma correction circuit 11 Luminance signal matrix circuit 12 Color signal matrix circuit 13 Encoder

Claims (1)

(57) [Claims] 1. A solid-state image pickup device of a predetermined color is spatially shifted by 1/2 picture element pitch from another solid-state image pickup device, and
A multi-plate solid-state color imaging device that forms a contour compensation signal from an imaging output signal from a solid-state imaging device of a predetermined color, and performs contour compensation on an imaging output signal from each solid-state imaging device by adding the contour compensation signal. In the apparatus, the reference level and the signal of a charge detection signal which repeats a reference level portion for each bit of the output of each solid-state imaging device and a signal portion charged or discharged from the reference level in accordance with an output charge. A charge detection circuit that outputs a difference from the level of the solid-state imaging device as an imaging output signal of each solid-state imaging device; and a predetermined sampling pulse that outputs the imaging output signal of the predetermined color solid-state imaging device supplied from the charge detection circuit. A sample-and-hold circuit that outputs a sample-and-hold signal according to a predetermined color; A contour compensation circuit for forming a contour compensation signal from an image pickup output signal of the element, and an image pickup output signal of the solid-state image pickup element of the predetermined color supplied from the charge detection circuit via the contour compensation circuit. An adder for adding the formed contour compensation signal; and an adder for adding the contour compensation signal formed by the contour compensation circuit to the imaging output signal of the other color solid-state imaging device supplied from the charge detection circuit. And a variable delay circuit for delaying a predetermined sampling pulse supplied to the sample hold circuit, wherein the imaging output signal of the solid-state imaging device of a predetermined color supplied to the adder via the contour compensation circuit; The delay amount of the variable delay circuit is reduced to a delay amount in consideration of a relative delay with respect to an imaging output signal of the solid-state imaging device of the other color supplied from the charge detection circuit to the adder. Configuration and the solid color imaging apparatus characterized by the sampling with the delay amount so as to operate the sample-and-hold circuit.