JPH0468687A - Color solid-state image pickup device - Google Patents

Abstract

PURPOSE:To dispose the arrival order of a signal according to spatial picture element arrangement by shifting either of uneven numbered or even numbered bit in the vertical direction to be read earlier. CONSTITUTION:A shift correction circuit 9 is composed of a sampling hold circuit 10 sampling the signal of uneven numbered bit, a sample and hold circuit 11 sampling the signal of even numbered bit, a delay circuit 12 delaying the circuit 11 by one horizontal cycle, and a switching circuit 13 receiving the output of the circuit 10 and the delay circuit 12 and outputting this after switching. The circuit 13 is switched for each 1 bit, and it transmits the delayed signal only to the even numbered bit signal read out earlier, further, transmits the signal not delayed to the uneven numbered bit signal to the next step. Thus, the signal is turned to be the order according to the spatial picture element arrangement of the color filter array of a CCD 1, and the color separation is performed without fail.

Description

[Detailed description of the invention] The present invention will be described in the following order.

A. Industrial field of application B1 Overview of the invention C1 Prior art C Figs. 3 and 4] a. First conventional example [Fig. 3] b6 Second conventional example [Fig. 4] B8 Solved by the invention Problem to be solved [Figure 5] E1 Means for solving the problem F2 Effect G, Examples [Figures 1 and 2] a. One embodiment [Figure 1] b. Other implementations Example [Figure 2] H1 Effect of the invention (A, industrial application field) The present invention relates to a color solid-state imaging device, particularly a color solid-state imaging device in which a solid-state imaging device is line-sequentially coded so that filters of different colors are adjacent to each other in the horizontal direction. Related to solid-state imaging devices.

(B. Summary of the Invention) The present invention solves the problem that, in the color solid-state imaging device described above, horizontal stripes or flicker occur when the level of a signal of the same color changes electrically in relation to signals of an adjacent color. In order to prevent
) by shifting bits in the vertical direction and reading it out earlier so that horizontal lines of the same color exist, and spatially adjusting the order of arrival of signals after the source of horizontal stripes or flicker in the video signal processing circuit. This is provided with a shift correction circuit that corrects the pixel arrangement so that it matches the pixel arrangement.

(C, Prior art) C Fig. 3, Fig. 4 3 (a, First embodiment) [Fig. 3] Fig. 3 (A) shows frame readout line sequential color coding Color color coding of a color solid-state imaging device Give an example,
FIG. 2B also shows a video signal processing circuit.

In the color coding example shown in Figure 3 (A), for frame readout, G/H sequential signals are output for odd lines and G/B dot sequential signals are output for even lines in both even and odd fields. be done.

Next, the video signal processing circuit shown in FIG. 3(B) will be explained.

1 is a CCD, 2 is a CDS (correlated double sampling circuit), 3 is an AGC (automatic gain control circuit), 4 is a sample hold circuit that samples the edge (G) signal, and 5 is a red (R) and blue (B) ), 6 is a color difference matrix that obtains color difference signals R-Y and B-Y from the output of the sample and hold circuit 4.5;
7 is the luminance signal Y from the output of the sample and hold circuit 4.5
8 is the sample and hold circuit 4
Vertical aberration signal Y v from the output G (Gr%Gb) of
It is a vertical abacon that obtains an ap.

In this color solid-state imaging device, the output signal of the CCD 1 passes through the CD 52 and the AGC 3, and then is color-separated. Then, the pressure of the sample hold circuit 4 is on the G/H line (
A line-sequential signal Gr/Gb is made up of the green signal Gr on the odd-numbered line and the green signal Gb on the G/B line (even-numbered line). Further, the output of the sample and hold circuit 5 becomes an R and B line sequential signal.

(b, Second Conventional Example) [Figure 4] Figure 4 (A) shows an example of color coding of a color solid-state imaging device with sequential color coding for all pixel readout lines;
) indicates a video signal processing circuit.

The all-pixel readout color solid-state imaging device attempts to obtain 525 lines of information in one field from the CCD, and the CCD pressure, which is one in frame readout, becomes two. Then, in frame readout, the V Abacon signal, which was applied using a signal that is two pixels apart in the vertical direction, can be applied using a signal that is one pixel apart. /
2 TV lines can be applied at a higher frequency and the vertical resolution can be increased.

This color solid-state imaging device has two CCD pressures, so the CD
S, AGC also 2 each (2a, 2b and 3a, 3b)
Yes, and there are 4 sample and hold circuits 4a and 4b
, 5a, and 5b.

(D. Problems to be Solved by the Invention) [FIG. 5] By the way, conventional color solid-state imaging devices have a problem in that horizontal stripes or flickers occur. This problem will first be explained using the frame readout line sequential color coding color solid-state imaging device shown in FIG. 3 as an example.

FIG. 5 shows the output waveform of CD52 of the color solid-state imaging device.
In particular, it shows the output waveform when cyan (Cy) is photographed. Cy has B and G components, but does not have an R component, so the output of R is O. In the figure, Gr is G (green) when it is an odd line where G and R are output alternately, as mentioned before, and Gb is when it is an even line where G and B are output alternately. G (green), and should originally be at the same level. However, the levels of Gr and Gb may not be the same due to the frequency characteristics of the CD52. This is because, due to frequency characteristics, the neighboring R signal affects the Gr signal, the neighboring B signal affects the Gb signal, and the levels of Gr and Gb are affected by the neighboring color R or B. .

Since the vertical aberration converter 8 performs signal processing to emphasize the difference for each LH (horizontal period), the level difference between Gr and Gb appears as unsightly horizontal stripes. Therefore, if you are concerned about these horizontal stripes and do not apply vertical aberration, the image will be blurred in the vertical direction. In other words, the outline becomes vague.

The level difference between Gr and Gb appears as horizontal stripes in a frame readout color solid-state imaging device, but appears as flicker in the all-pixel readout color solid-state imaging device shown in FIG.

In addition, in the case of a color solid-state imaging device with all pixel readout, it is important to consider not only the frequency characteristics of the CD52 (CD52, A
Since there are two circuits of the GC3, linearity mismatch and gain mismatch between the two systems also cause a level difference between Gr and Gb, giving rise to the possibility that more noticeable flicker will occur.

The present invention has been made to solve these problems, and is intended to solve the problem that horizontal stripes or flicker occur when the level of a signal of the same color changes electrically in relation to the signal of an adjacent color. The purpose is to prevent.

(E. Means for Solving the Problems) In order to solve the above-mentioned problems, the color solid-state imaging device of the present invention has a solid-state imaging device that shifts one of the odd-numbered bits and even-numbered bits in the vertical direction. By reading out horizontal lines of the same color, a shift correction circuit is installed after the source of horizontal stripes or flicker in the video signal processing circuit to correct the arrival order of signals so that they match the spatial pixel arrangement. It is characterized by having been established.

(F. Effect) According to the color solid-state imaging device of the present invention, according to the spatial pixel arrangement, for example, where sequential outputs of filters of different colors of G/R and G/B occur, odd bits and even bits in the horizontal direction are By shifting one of the bits, for example, by 2 (or 1) in the vertical direction and reading, the signal of the filter of the same color, for example, GGGGGGGG..., and the signal of the filter of the same color, for example, R/B dot sequentially, are read out. You can get the output signal.

For example, when filter signals of the same color, such as GGGGGGGG..., are input to the CDS, there is no possibility that G will be mixed with other colors R or B in the CDS. That is, there is no possibility that the level of a signal of the same color will electrically change in relation to the signal of an adjacent color. Therefore, horizontal stripes or flicker due to color mixture will not occur.

Then, signals arranged in an order different from the spatial pixel arrangement are returned to the order according to the spatial pixel arrangement by a shift correction circuit at a stage subsequent to the circuit that causes flicker or horizontal stripes, such as CDS or AGC. By shifting one of the bits and the even-numbered bits by an appropriate amount of bits in the vertical direction and reading them out quickly, flicker and horizontal stripes can be removed, thereby eliminating the possibility of interfering with signal processing.

(G. Embodiment) [FIGS. 1 and 2] Hereinafter, the color solid-state imaging device of the present invention will be described in detail according to the illustrated embodiment.

(a, one embodiment) [Fig. 1] Fig. 1 (A) to (C) show one embodiment of the color solid-state imaging device of the present invention, and Fig. 1 (A) is a color coding diagram; Figure (B) is a circuit diagram of the video signal processing circuit;
C) is an operation explanatory diagram.

In this embodiment, the present invention is applied to a frame readout color coding color solid-state imaging device.

The color coding is exactly the same as that of the color solid-state imaging device (first conventional example) shown in FIG.

By the way, there is a big difference between the video signal processing circuit shown in FIG. 1(B) and the video signal processing circuit shown in FIG. 3(,B).

First, the solid-state image sensor 1 is different from conventional ones,
For even-numbered bits (even-numbered bits counting horizontally, in other words, bits in even columns),
It is now possible to read bits faster.

This sets 2 bits in the register of odd bits (odd bits counting horizontally, in other words bits in odd columns).
Delay means (dummy bit) that causes a bit delay
This can be easily achieved by, for example, providing a

In this way, the output of CCD 1 becomes as shown in FIG. 1(C). For both the odd field and the even field, eight signals GGGG... are sent for odd-numbered horizontal lines. ○ in the diagram
The signal surrounded by is the signal that has been shifted by 2 bits in the vertical direction and read out. And this GGGG...
This signal is contour-enhanced by the vertical aberration converter 8. Since this edge-enhanced signal G is output as a filter signal of the same color, it is possible to avoid the conventional problem of color mixing occurring in the CD52, resulting in level fluctuations in Gb and G, and as a result, horizontal stripes are likely to occur. .

That is, CCD 1 is arranged according to the spatial pixel arrangement as in the conventional
When reading the signal from , the odd horizontal line is GBG
B..., the even numbered horizontal line is RGRG...
. . . The point-sequential output signals of filters of different colors are always input to the CD 52, and since G, whose contour is emphasized by the vertical aberration controller 8, is always adjacent to R or B, C
D52 (and AGC3) electrically causes color mixing due to its frequency characteristics, which causes horizontal stripes. However, according to this color solid-state imaging device, G is input to the CD 52 in a form that is not adjacent to signals of different colors, so G causes electrical color mixing with adjacent signals in the CD 52 (and AGC 3). There is no danger. Therefore, it is possible to prevent horizontal stripes from occurring.

Figure 3 (E) of the video signal processing circuit of this color solid-state imaging device
The second difference from the video signal processing circuit shown in ) is that it includes a shift correction circuit 9.

As mentioned above, since the even-bit signal from CCD 1 is shifted 2 bits vertically relative to the odd-bit signal and read out earlier, the signal that has passed through CD52 and AGC3 is read out before color separation. It is necessary to correct the readout order to conform to the spatial pixel arrangement, and the shift correction circuit 9 performs this correction.

The shift correction circuit 9 includes a sample and hold circuit 10 that samples signals of odd bits, a sample and hold circuit 11 that samples signals of even bits, and a delay circuit 12 that delays the sample and hold circuit 11 by one horizontal period (IH). , a switching circuit 13 that receives the output of the sample and hold circuit 10 and the output of the delay circuit 12, and switches and outputs the output. The switching circuit 13 switches bit by bit, and sends out to the next stage a signal delayed by IH only for even-numbered bit signals read earlier, and a signal that is not delayed for odd-numbered bit signals. This causes the signals to be ordered according to the spatial pixel arrangement of the color filter array of CCD 1. Therefore, color separation can be performed without any problem. In other words, horizontal stripes can be prevented while color separation can be performed without any problem.

(b, Other Embodiments) [Fig. 2] Fig. 2 (A) to (C) show other embodiments of the color solid-state imaging device of the present invention, in which (A) is a color coding diagram; The same figure (B) is a circuit diagram of the video signal processing circuit, the same figure (C
) is an operation explanatory diagram.

In this embodiment, the present invention is applied to a color solid-state imaging device with sequential color coding for all pixel readout lines, and the color coding is exactly the same as that shown in FIG. 4(A).

In this color solid-state imaging device, CCD 1
is designed to read out one bit earlier in the vertical direction for even-numbered bit signals. This can be easily realized by providing one dummy bit (delay means) in the odd column register.

In this way, as shown in FIG. 4(C), the CCD
The 8 power of channel 1 of 1 becomes GGGG... In this way, G whose vertical contour is emphasized by the vertical abercon 8 is always outputted from channel 1 as CD S , 2
In conventional all-pixel readout color solid-state imaging devices, flicker occurs due to the frequency characteristics of the CD52, or due to the level difference between Gb and Gr due to linearity or gain mismatch between the two channels. The problem can be avoided.

In addition, in this color solid-state imaging device, even-numbered bit signals are shifted by one bit in the vertical direction and read out quickly (CD
It is necessary to correct the order of the signals passing through 52a, 2b and AGC 3a, 3b to conform to the spatial pixel arrangement.
The shift correction circuit 9 performs the correction.

The shift correction circuit 9 of this color solid-state imaging device includes a CCD 1
A sample and hold circuit 10a samples the odd bits of the output signal of the first channel AGC 3a of the same, a sample and hold circuit 11a samples the even bits of the same, and a sample and hold circuit 11a samples the output signal of the second channel AGC 3b of the CCD 1.
A sample and hold circuit 10b that samples the odd bits of the output signal of the sample and hold circuit 11b that also samples the even bits, a delay circuit 12 that delays the output signal of the sample and hold circuit 11a by one horizontal period (IH), and a switching circuit 13a, 13b roars.

The switching circuit 13a is the sample hold circuit 10a.
The output signals of and llb are switched bit by bit and output.
The switching circuit 13b is the sample hold circuit 10b.
and the output signal of the delay circuit 12 are switched bit by bit and output. This shift correction circuit 9 is more complex than the shift correction circuit 9 of the color solid-state imaging device shown in FIG. This is because the amount of information is larger than that of a solid-state imaging device.

It is possible that flicker may occur due to calculation errors in the shift correction circuit 9, but this can be satisfactorily resolved by digitizing the stages subsequent to the AGCs 3a and 3b. Further, although the shift correction circuit 9 is somewhat complicated, there is a possibility that it can be further simplified if it is integrated with the subsequent matrices 6 to 8.

(H, Effect of the Invention) As described above, in the color solid-state imaging device of the present invention, filters of different colors are line-sequentially coded horizontally so that they are adjacent to each other, and either odd-numbered bits or even-numbered bits are A solid-state image sensor that reads out signals so that horizontal lines of the same color exist by shifting bits appropriately in the direction, and a correction that corrects the order in which the signals arrive at a stage subsequent to the circuit where horizontal stripes or flicker occurs so that they match the spatial pixel arrangement. The present invention is characterized by comprising a signal processing circuit having a shift correction circuit that performs the following steps.

Therefore, according to the color solid-state imaging device of the present invention, according to the spatial pixel arrangement, for example, when sequential outputs of filters of different colors of G/R and G/B occur, either odd number bits or even number bits are output. For example, by shifting appropriate bits, for example, 2 (or l) in the vertical direction and reading out, for example, the same color filter signal and R/B point sequential pressure signal of GGGGGGGG... can be obtained. I can do it.

For example, when the filter signals of the same color, such as GGGGGGGG..., are input to the CDS, there is no risk of color mixing occurring in the CDS or AGC, etc., and mixing with other colors, so the same color There is no possibility that the level of the signal of the color changes electrically in relation to the signal of the adjacent color. Therefore, horizontal stripes or flicker due to color mixture are less likely to occur.

Then, the shift correction circuit restores the order of the signal that is different from the spatial pixel arrangement to the spatial pixel arrangement, so signal processing is performed by appropriately shifting either the odd bits or the even bits in the vertical direction. There is no risk of any interference.

[Brief explanation of drawings]

Figures 1 (A) to (C) show one embodiment of the color solid-state imaging device of the present invention, where (A) is a color coding diagram and Figure 1 (CB) is a circuit block of a video signal processing circuit. Figure 2 (C) is an output diagram of the solid-state imaging device for explaining the operation, and Figures 2 (A) to (C) show other embodiments of the color solid-state imaging device of the present invention. A) is a color coding diagram, CB) is a circuit block diagram of the video signal processing circuit, (C) is a solid-state image sensor output diagram to explain the operation, and Figures 3 (A) and (B) are The first conventional example is a frame readout line sequential color coding color solid-state imaging device, in which (A) is a color coding diagram, (B) is a circuit diagram of a video signal processing circuit, and FIG. 5 shows a second conventional example of an all-pixel readout line sequential color coding color solid-state imaging device, in which (A) is a color coding diagram, (B) is a circuit diagram of a video signal processing circuit, and FIG. is a CD that explains the problem that the invention aims to solve.
It is an S output waveform diagram. Explanation of symbols 1... Solid-state image sensor, 2... CDS (correlated double sampling circuit)
, 3...AGC (automatic gain control circuit), 4.5
...Sample hold circuit, 9...Shift correction circuit.

Claims (1)

[Claims] (1) Filters of different colors are line-sequentially coded so that they are adjacent to each other in the horizontal direction, and one of the odd-numbered bits and even-numbered bits in the horizontal direction is read out quickly by shifting the bits appropriately in the vertical direction. A solid-state image sensor that outputs signals so that horizontal lines of the same color exist, and a shift correction circuit that corrects the arrival order of the signals so that they match the spatial pixel arrangement, which is located after the circuit where horizontal stripes or flicker occurs. A color solid-state imaging device comprising: a video signal processing circuit having: