JP2655436B2 - Color solid-state imaging device - Google Patents

Description

The present invention relates to a color solid-state imaging device.

[Conventional technology]

As one method for obtaining a color television signal using one image sensor, a signal representing two types of chromaticity information is frequency-multiplexed using four types of color filter elements of magenta and green, yellow and cyan, and an image sensor is obtained. There is a known method of taking out. FIG. 4 shows an arrangement of color filter elements according to the conventional method. In the drawing, the color filter array 27 has a magenta filter (Mg) 28 and a green filter (G) 29 alternately arranged in the n-th (n = 1 + 4i, i = 0, 1, 2,...) Row, and the (n + 2) th The Mg filter and the G filter are arranged in the n-th row in the opposite phase to the n-th row. Similarly, the yellow filter (Ye) 30 and the cyan filter (Cy) 31 are arranged in the (n + 1) -th and (n + 3) -th rows. They are arranged alternately.
In the first field, the image pickup element adds the signal charges of the nth and (n + 1) th light receiving elements vertically adjacent to each other to generate the Nth (N = i + 1) th scanning line signal and the (n + 2) th scanning line signal. And the signal charge of the (n + 3) th light receiving element are added to obtain the (N + 1) th scanning line signal. FIG. 5 shows a configuration example of a conventional color imaging device. From the Nth scanning line signal of the output signal obtained from the image sensor 7, (Mg
+ Ye) and (G + Cy) as 2R-G
Similarly, from the (N + 1) th scanning line signal, a 2B-G modulated component is obtained from the (Ye + G) and (Cy + Mg) components. This modulated component is separated by the bandpass filter 8 and the demodulation circuit 11 After that, the 1H delay line 32 and the 1H switch circuit 33 synchronize and obtain two color difference signals. Low pass filter 16
Obtains a luminance signal from the output of the image sensor 7, processes the luminance signal in the process circuit 17, and combines the luminance signal with two color difference signals by the color encoder 18 to obtain a color video signal.

[Problems to be solved by the invention]

In the above-described conventional technique, two color difference signals are obtained as modulation components by two pixels adjacent in the horizontal direction, so if there is a change in brightness in the horizontal direction, for example, in a contour portion of an image, this change in brightness is used as a modulation component. There is a problem that is output. As a result, a strong false color signal is generated at the outline,
There is a disadvantage that the image quality of the reproduced image is significantly deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved color imaging apparatus which eliminates the above-mentioned conventional disadvantages, does not generate a false color signal at the outline of an image, and does not deteriorate image quality.

[Means for solving the problem]

The color solid-state imaging device according to the present invention has an n-th (n = 1 + 4)
i, i = 0, 1, 2,...), the first magenta color
And the second color filter of green are alternately arranged, and the third color filter of yellow and the fourth color filter of cyan are alternately arranged on the light receiving elements in the (n + 1) th row. The first and second color filters are arranged in the light receiving element in the (n + 2) th row in the opposite phase to the nth row, and the third and fourth colors are provided in the light receiving element in the (n + 3) th row. In a color solid-state imaging device including at least a two-dimensional solid-state imaging device in which a color filter array in which a filter is arranged in a phase opposite to that of the (n + 1) th row is combined,
In the first field, the solid-state imaging device includes the nth (n = 1 + 4i, i = 0, 1, 2,...) And n +
The Nth (N = 1 + i) scanning line signal is obtained by adding the signal charges of the first light receiving element, and the N + th (N + 2) th and (n + 3) th light receiving elements are added by adding the signal charges of the (n + 2) th and (n + 3) th light receiving elements.
The means for obtaining the first scanning line signal and the M-th (M = 1 + i) scanning line signal by adding the signal charges of the (n + 1) th and (n + 2) th light receiving elements in the second field, Means for obtaining the (M + 1) th scanning line signal by adding the signal charges of the (n + 3) th and (n + 4) th light receiving elements. And a color difference signal of red and green as a first chromaticity signal from the (N + 1) th scanning line signal. Similarly, in the second field, the Mth and M + th signals are obtained.
Means for obtaining a blue and green color difference signal as a second chromaticity signal from a first scanning line signal; and simultaneously delaying the first and second chromaticity signals obtained in the field sequence alternately for one field period. Means for simultaneously obtaining the two chromaticity signals in each field.

[Action]

According to the present invention, in order to solve the above-mentioned conventional problem, signals representing the same first chromaticity information in a first field are similarly applied to two vertically adjacent scanning lines in a second field. In the field, color filters are arranged so that signals representing the same second chromaticity information are included as modulation components having phases opposite to each other for each scanning line, and two adjacent scanning line signals are sequentially field-separated from the two adjacent scanning line signals. The signal representing the chromaticity information is obtained by separating the signals representing the two pieces of chromaticity information. The obtained signal representing the chromaticity information has a higher resolution in the horizontal direction than the conventional example. A color image that can be improved and has little deterioration in image quality can be obtained.

〔Example〕

 Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an arrangement of color filters for a color solid-state imaging device according to the present invention.

This arrangement is, as shown in FIG.
Is a magenta filter (Mg) 2 (first color filter) and a green filter (G) 3 (second color filter) in the n-th (n = 1 + 4i, i = 0, 1, 2,...) Row. Are alternately arranged, and the n-th
In the + 2nd row, the Mg filter and the G filter are arranged in opposite phases to the nth row, and in the (n + 1) th row, the yellow filter (Ye) 4 (third color filter) and the cyan filter (C
y) 5 (fourth color filters) are alternately arranged, and
In the third row, a Ye filter and a Cy filter are arranged in a phase opposite to that of the (n + 1) th row.

A light receiving element of a solid-state image sensor corresponds to each color filter of the color filter array. Therefore, light from the subject passes through this color filter array and forms an image on the light receiving element.

In the first field, in the first field, the signal charges of the light-receiving elements in the n-th and (n + 1) -th rows adjacent in the vertical direction are added for each column, and the N-th (N = 1 + i) scanning line signal is generated. The signal charges of the light receiving elements in the (n + 2) th and (n + 3) th rows are added for each column to obtain the (N + 1) th scanning line signal. Similarly, in the second field, the (n + 1) th and (n) th scanning line signals are obtained.
The signal charges of the light receiving elements in the + 2nd row are added for each column, and the Mth (M = 1 + i) scanning line signal is added, and the signal charges of the light receiving elements in the (n + 3) th and (n + 4) th rows are added for each column. In addition, an operation is performed to obtain the (M + 1) th scanning line signal.

Next, FIG. 2 is a configuration diagram showing a first embodiment of the color solid-state imaging device of the present invention.

In the figure, the color filter array shown in FIG. 1 is combined with the image sensor 7a. As described above, in the first field, the Nth scanning line signal is obtained by adding the signal charges of the light receiving elements in the nth and (n + 1) th rows which are vertically adjacent to each other in the first field. The (N + 1) th scanning line signal is obtained by adding the signal charges of the light receiving elements in the (n + 2) th and (n + 3) th rows for each column. Therefore, a signal (Mg + Ye) obtained by adding Mg and Ye and a signal (G + Cy) obtained by adding G and Cy are alternately obtained from the Nth scanning line signal. Similarly, from the (N + 1) th scanning line signal, an added signal component is the same as that of the (N) th scanning line, but an output signal having an opposite phase is obtained. Next, in the second field, as described above, the n +
The signal charges of the light receiving elements in the first and (n + 2) th rows are added for each column, and the Mth scanning line signal adds the signal charges of the light receiving elements in the (n + 3) th and (n + 4) th rows for each column. In addition, an (M + 1) th scanning line signal is obtained.
The signal obtained by adding Ye and G (Ye +
G) and a signal obtained by adding Cy and Mg (Cy + Mg), and a signal component added from the (M + 1) th scanning line signal is Mth.
Output signals which are the same as the first scanning line, but whose phases are opposite are obtained alternately. This is different in the combination to be added to the first field.

Each scanning line signal includes the following signal component as a modulation component. That is, (Mg + Ye) − (G + Cy) = 2R−G is included in the Nth scanning line signal of the first field,
The (+1) th scanning line signal includes G-2R, and the (M) th scanning line signal of the second field includes (Ye + G)-(Cy + M
g) = G−2B, similarly, the (M + 1) th scanning line signal has 2
BG is included. That is, in the first field, R and G color difference signals representing the first chromaticity information are obtained, and in the second field, B and G color difference signals representing the second chromaticity information are obtained. Since this modulation component has an opposite phase for each scanning line for each field, if this is calculated and added between two scanning lines, the sampling frequency of the color difference signal in the horizontal direction is doubled, and an image having a higher spatial frequency is obtained. However, the generation of the false color difference signal in the outline portion is eliminated.

This modulation component is separated by the bandpass filter 8a. The separated modulation component is delayed by one horizontal scanning period by the 1H delay line 9a.
The delayed modulation component is added by the adding circuit 10a with matching polarity so as to be added to the original modulation component that is not delayed. The added modulation component is demodulated by the demodulation circuit 11a.
From the demodulated signal, the two types of color difference signals described above are obtained in the field sequence. After delaying this for one field period by the 1V delay circuit 12a, the 1V switching circuit 13a switches every field and synchronizes the two color difference signals. obtain. The two obtained color difference signals are modulated by the modulation circuits 14a and 15a to obtain two modulated color signals.

The low-pass filter 16a obtains a luminance signal from the output of the image sensor 7a. This is subjected to processing such as gamma correction by the process circuit 17a, and then combined with the two modulated color signals by the color encoder 18a to obtain a color video signal.

Next, FIG. 3 is a configuration diagram showing a second embodiment. In the figure, a bandpass filter 8b, a 1H delay line 9b, an adder circuit 10b, and a demodulator circuit 11b are output from the image sensor 7b in the same manner as in the first embodiment.
To separate and obtain the color difference signals. On the other hand, the low-pass filter 19 obtains a low-frequency luminance signal from the output of the image sensor 7b. This is added to the color difference signal demodulated in the adding circuit 20, and only the R and B signal components are extracted. The extracted R and B signals are subjected to processes such as gamma correction in a narrow band RL process circuit 21 and a BL process circuit 22. Similarly, the YL process circuit 23 performs processing such as gamma correction on the low-frequency luminance signal. RL process circuit 21, BL
Subtraction circuit from output of process circuit 22, YL process circuit 23
At 24 and 25, a color difference signal is formed again. Since the color difference signals are field sequential, they are switched by a 1V switching circuit.
Subsequent operations are the same as in FIG.

This embodiment has an advantage that color reproducibility is improved because R and B signals are extracted from two color difference signals obtained by demodulation by the demodulation circuit 11b, and the R and B signals are subjected to gamma correction processing.

The output signal of the image sensor may be delayed by a 1H delay line for a 1H period, and the modulation component representing the two pieces of chromaticity information may be separated and obtained from the 1H delay signal and the original output signal that is not delayed. The effect is the same.

〔The invention's effect〕

As described above, according to the present invention, the modulation component included in each scanning line is a signal component having the opposite phase for each scanning line, and by separating this from the two scanning lines, two chromaticities are obtained. The horizontal resolution of a signal representing information can be increased, and the occurrence of a false color signal at the outline of an image is reduced. As a result, a color solid-state imaging device with improved image quality can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an arrangement of color filters for a color solid-state imaging device according to the present invention, FIG. 2 is a configuration diagram showing a first embodiment of the present invention, and FIG. FIG. 4 is a diagram showing the arrangement of a conventional color filter, and FIG. 5 is a diagram showing the configuration of a conventional color image pickup apparatus. 1 ... color filter array, 2 ... magenta filter, 3
... green filter, 4 ... yellow filter, 5 ... cyan filter, 7, 7a, 7b ... image sensor, 8, 8a, 8b ... band-pass filter, 9a, 9b ... 1H delay circuit, 10a, 10b ... ... Addition circuit, 11,1
1a, 11b: Demodulation circuit, 12a, 12b: 1V delay circuit, 13a, 13b
…… 1V switching circuit, 14a, 14b, 15a, 15b …… Modulation circuit, 16,16
a, 16b: Low-pass filter, 17, 17a, 17b: Process circuit, 18, 18a, 18b: Color encoder, 19: Low-pass filter, 20: Addition circuit, 21, 22, 23: Process Circuit, 2
4, 25 ... subtraction circuit, 26 ... 1 V switching circuit, 27 ... color filter array, 28 ... magenta filter, 29 ... green filter, 30 ... yellow filter, 31 ... cyan filter, 32 ...
1H delay circuit, 33 ... 1H switching circuit.

Claims (1)

(57) [Claims] 1. A magenta first color filter and a green second color filter are alternately arranged on the light receiving elements in the n-th (n = 1 + 4i, i = 0, 1, 2,...) Row. The third color filters of yellow and the fourth color filters of cyan are alternately arranged on the light receiving elements of the (n + 1) th row, and the first and second light filters are arranged on the light receiving elements of the (n + 2) th row. Are arranged in phase opposition to the n-th row, and the third and fourth color filters are arranged in phase opposition to the (n + 1) -th row in the light receiving elements in the (n + 3) -th row. In a color solid-state imaging device including at least a two-dimensional solid-state imaging device in which a configured color filter array is combined, the solid-state imaging device is an n-th (n) vertically adjacent pixel in a first field.
= 1 + 4i, i = 0, 1, 2,...) And the signal charge of the (n + 1) th light receiving element, and the Nth (N = 1 + i) th scanning line signal is added to the (n + 2) th and (n + 3) th scanning line signals. Means for obtaining the (N + 1) th scanning line signal by adding the signal charges of the light receiving elements, and similarly, for the second field, adding the signal charges of the (n + 1) th and (n + 2) th light receiving elements to the Mth ( The scanning line signal of M = 1 + i) is converted to the (n + 3) th
Means for obtaining the (M + 1) th scanning line signal by adding the signal charges of the (n) th and (n + 4) th light receiving elements, and the Nth and (N + 1) th fields in the first field from the output signal of the solid-state imaging device. A red and green color difference signal is obtained as a first chromaticity signal from the first scanning line signal. Similarly, in the second field, blue is obtained as a second chromaticity signal from the Mth and (M + 1) th scanning line signals. Means for obtaining a color difference signal between the first and second chromaticity signals;
Means for alternately delaying and synchronizing field periods to simultaneously obtain the two chromaticity signals in each field.