JPH0374991A - Drive method for solid-state image pickup device - Google Patents

Abstract

PURPOSE:To double sensitivity substantially by changing the vertical adjacent four picture elements mixing system into the vertical adjacent four picture elements mixing system equivalently when the illuminance of an object is insufficient in the case of the high brightness operation. CONSTITUTION:The vertical adjacent four picture elements mixing system is changed into the vertical adjacent four picture elements mixing system equivalently when the illuminance of an object is insufficient in the case of the high brightness operation. That is, 1st columns C11, C21, C31, C41 of a unit matrix of two-columns and four-rows are arranged for yellow(Ye), magenta(Mg), yellow(Ye) and green(G) in this order and 2nd columns C12, C22, C32, C42 are arranged for cyan (Cy), G, Cy, magenta Mg in this order. As a result, same luminance signal and color difference signal are obtained, a color composite video signal is synthesized and the luminance signal is doubled for the luminance signal in the normal operation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for driving a solid-state imaging device capable of capturing images with high sensitivity.

2. Description of the Related Art As home movies have become more popular in recent years, the competition for high-sensitivity movies has intensified. In order to increase the sensitivity of this type of movie, efforts are being made to improve the S/N of the solid-state image sensor itself.

Problems to be Solved by the Invention In current movies, a minimum object illuminance of several EX is commercially available, but the output S/
There is a limit to dramatically improving the N characteristics.

Means for Solving the Problems In order to solve the above problems, when the subject illuminance is insufficient in the solid-state imaging device driving method of the present invention, the vertically adjacent 2-pixel mixing method is equivalently changed to the vertically adjacent 4-pixel mixing method. Instead, the method for driving a color solid-state imaging device has timing for performing color separation.

Effects In the present invention, with the above configuration, it is possible to achieve twice as high sensitivity characteristics as it equivalently mixes four pixels, compared to the field accumulation coloring method that uses two pixels.

EXAMPLE The present invention will be explained below by way of an example with reference to the drawings. FIG. 1 shows a schematic diagram of a color filter of a solid-state imaging device used in the present invention.

In the present invention, the first column CI I r of a unit array of 2 columns and 4 rows
C21, C31, C41 are yellow (Ye), magenta (
Mg).

The colors are arranged in the order of yellow (Ye) and green (G), with the second column being cyan (Cy), green (G), and cyan (Cy).

They are arranged in the order of magenta (Mg), and each color filter CI1. CI2 corresponds to 1=1 for a solid-state image sensor (for example, a light receiving element of an interline transfer type CCD).

Next, methods of color separation using this solid-state imaging device will be described for (1) normal operation and (2) high-sensitivity operation.

(1) In normal operation, in the n line of the first field scan, two adjacent pixels in the vertical direction are mixed, and the image sensor signal output is C+
+ (Ye) + C21 (Mg) and C22 (G) + C32
(Cy) is repeated.

In the first field, line n+1, the signal output is C31 (Ye) + C41 (G) and C32 (Cy) +
C42 (Mg) is repeated.

In the second field, line n, the signal output is C2
+ (Mg) + C31 (Ye) and C22 (G) + C32
(Cy) is repeated.

In the second field, line n+1, the signal outputs are C41 (G) + C51 (Ye) and C42 (Mg) +
C52 (Cy) is repeated.

FIG. 2 shows the state of signal output in the case of the above-mentioned vertically adjacent two-pixel mixing method. Here, the primary color components red, green, and blue are R, G
, B, it is expressed as Cy=B+G, Ye3R+G, MgmiR+B.

The element signal output shown in FIG. 2 is passed through an electric bandpass filter to obtain the difference between the first column and the second column, and the color difference signals CI and C2 shown below are obtained.

1st field, n line C1 3(2R+G+B)-(2G+B)=2R-G 1st
Field, on the n+1 line, C23 (R+2G) - (R1G+2B) = G-2B Similarly, in the second field, on the n line, C13 (2R1G+B) - (2G+B) = 2R - G2
In the field and line n+1, C23(R+2G)-(R1G+2B)=G-2B.

On the other hand, the first column and the second column are added by electrically low-pass filtering the luminance signal YiJ, the signal in FIG. 2.

In the 1st field, n line, Ymi (2R1G1B) + (2G1B) = 2R + 3G + 2
Similarly to B, in the first field, line n+1, Y3R+2G+R+G+2B=2R+3G+2B Similarly, in the second field, line n, line n+1, Y=2R+3G+2B, and the luminance signal Y and two different color difference signals CI*C2
A color composite video signal can be synthesized from

Q) In the case of high-sensitivity operation The state of image sensor signal output and signal processing in the color filter configuration shown in FIG. 1 is explained in Section 3. It is shown in Figure 4.

In Figure 3, n of the first field, n+10n+2
．． Of the n+3 line signal outputs, the n line and the n+1 line are added, and the result is set as the N line signal.

Regarding the n+2 line and the n+3 line of the first field, the output of the n+3 line is electrically delayed by 1 bit period and then added to the n+2 line output. The result is N+2
Use line signal.

From the N line signal to the N+2 line signal, a color difference signal c, , c2 is obtained by an electric band pass filter, and a luminance signal Y is obtained by an electric low pass filter.

That is, the color difference signal CI in the N line is CI = 2Y
e10-G+Mg-(2Cy+G+Mg)=2 (Ye-
Cy) Luminance signal material Y=2Ye+G+Mg+2Cy+G0Mg=
2Ye+2G+2Mg+2Cy=4R+6G+4B.

The color difference signal C2 on the N+2 line is C2=Ye+Cy+2Mg-(Ye+Cy+2G)=2
(Mg-G) and luminance signal Y=Ye+Cy+2Mg+Ye+Cy+2G=
2Ye+2G+2Mg+2Cy=4R+6G+4B.

Similarly, for the second field, as shown in FIG. 4, the luminance and color difference C1 of the N line signal are Y=2Ye+G+
Mg+2Cy+G10Mg=2Ye+2G+2Mg+2C
y=4R+6G+4B CI=2Ye+G+Mg-(2Cy+G+Mg)=
2 (Ye-Cy) The N+2 line signal is obtained by electrically delaying the n+3 line signal by 1 bit period and adding it to the n+2 line output signal. The luminance Y and color difference C2 of the N+2 line signal are Y=Ye+2Mg+Cy+Ye+2G+Cy=2Ye+
2G+2Mg+2Cy=4R+6G+4B Ct=Ye+2Mg+cy-(Ye+2G+Cy)=2
(Mg-G).

Therefore, the first. In the second field, the same luminance signal Y22 and color difference signal CI, C2 are obtained, and a color composite video signal can be synthesized.The luminance signal is twice as large as Y=4R+6G compared to the luminance signal Y=2R+3G+2B in normal operation.
+4B, making it possible to achieve twice the sensitivity.

Note that in the above embodiment, in the first field,
Although the n+3 line output is delayed by 1 bit period and in the second field, the n+3 line output is delayed by 1 bit period, similar results can be obtained even if the n+2 line output is delayed by 1 bit period in both fields.

Furthermore, in this embodiment, a 1-bit period delay is applied when combining the four charge-mixed signal outputs, but according to the present invention, when combining the four charge-mixed signal outputs, , a relative time shift may be provided between the four signal outputs, and the shift may be a time shift of an odd number of bits in the column direction.

Effects of the Invention According to the present invention, when the subject illuminance is insufficient, the vertically adjacent 2-pixel mixing method is equivalently changed to the vertically adjacent 4-pixel mixing method, so the sensitivity can be substantially doubled, and in effect, A solid-state imaging device with high sensitivity characteristics can be realized.

[Brief explanation of drawings]

FIG. 1 shows the color scheme according to the embodiment of the present invention.
...Output voltage, t...Time, R...
Red component, B...Blue component, G...Green component, cy...Cyan light transmission filter, Mg...
...Magenta light transmission filter, Ye...Yellow light transmission filter.

Claims (5)

[Claims] (1) Cyan (Cy), Yellow (Ye), Magenta (
Mg) and green (G) filter elements
A color filter array in which first, second, third, and fourth unit array elements arranged in two columns and rows are arranged in the column direction to form a unit array with two columns and eight rows; and each of the filter elements. and a photoelectric conversion element array of 2 columns and 8 rows consisting of first, second, third, and fourth photoelectric conversion unit array elements arranged in two columns and two rows in which individual photoelectric conversion elements are arranged facing each other. Driving the solid-state imaging device, mixing the charges photoelectrically converted by the photoelectric conversion elements adjacent in the column direction in each of the photoelectric conversion unit array elements to form a photoelectric conversion unit array element output; When combining the outputs of the second photoelectric conversion unit array element and the outputs of the third and fourth photoelectric conversion unit array elements, between the outputs of the tenth second, third, and fourth photoelectric conversion unit elements, A method for driving a solid-state imaging device, characterized in that composition is performed by adding a relative time lag. (2) The first column of the first unit array of the color filter array facing the photoelectric conversion unit array element is yellow (Ye) and magenta (Mg), and the second column is cyan (Cy) and green (
G), and in the second unit, the first column is yellow (Ye), green (G), and the second column is cyan (Cy).
, magenta (Mg), the first column of the third unit array is yellow (Ye), magenta (Mg), and the second column is cyan (Cy)
, green (G), the first column of the fourth unit array is yellow (Ye), green (G), the second column is cyan (Cy),
The method for driving a solid-state imaging device according to claim 1, wherein magenta (Mg) is used. (3) The first example of the first unit array of the color filter array facing the photoelectric conversion unit array element is yellow (Ye) and magenta (Mg), and the second row is cyan (Cy) and green (
G), the first column of the second unit array is cyan (Cy), magenta (Mg), the second column is yellow (Ye), green (
G), the first column of the third unit array is yellow (Ye), magenta (Mg), the second column is cyan (Cy), green (
G), the first column of the fourth unit array is cyan (Cy), green (G), the second column is yellow (Ye), magenta (M
The method for driving a solid-state imaging device according to claim 1, wherein the solid-state imaging device is arranged in the order of g). (4) When combining the first and second photoelectric conversion unit array element outputs and combining the third and fourth photoelectric conversion unit array element outputs, any one of the photoelectric conversion unit element array outputs has an odd number in the column direction. Claim 1: Synthesizing by adding a time difference for columns
A method for driving the solid-state imaging device described above. (5) When combining the outputs of the first and second photoelectric conversion unit array elements and the outputs of the third and fourth photoelectric conversion unit array elements, one row in the column direction is added to the output of any one photoelectric conversion unit array element. 2. The method of driving a solid-state imaging device according to claim 1, wherein the synthesis is performed by adding a time difference of minutes.