JPH0440092A - Method of driving solid image pickup device and method of processing signal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a driving method and a signal processing method for a solid-state imaging device having a solid-state imaging element capable of high-sensitivity imaging.

[Prior Art] In recent years, with the spread of household camera-integrated VTRs, there has been active development of higher sensitivity for camera-integrated VTRs. In order to achieve higher sensitivity of such a camera-integrated VTR, efforts are being made to improve the S/N of the solid-state image sensor itself that constitutes the camera-integrated VTR.

Further, by using field memory to perform exposure over a plurality of fields, the sensitivity of camera-integrated VTRs has been increased.

[Problem to be solved by the invention]

Currently, camera-integrated VTRs with a minimum subject illuminance of a few lux are on the market, but there is a limit to dramatically improving the output S/N characteristics of a solid-state image sensor using an interline transfer method, for example. be.

Furthermore, when using a field memory, the number of parts and cost increase, and there is a limit to the number of fields considering the unnaturalness of the output image.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a driving method and a signal processing method for a solid-state imaging device, which can provide a solid-state imaging device with high sensitivity and no unnaturalness in output images.

[Means to solve the problem]

The method for driving a solid-state imaging device according to claim (1) includes a photoelectric conversion unit array element in which signal charges photoelectrically converted by charge conversion elements adjacent in a column direction in a photoelectric conversion unit array element are mixed in the vertical transfer section. Furthermore, without operating the horizontal transfer section, the photoelectric conversion unit array element output for multiple lines is transferred from the vertical transfer section to the horizontal transfer section, and this horizontal transfer section transfers the photoelectric conversion unit array element output for each of the multiple lines. A drive that applies a relative time lag between array element outputs, combines the photoelectric conversion unit array element outputs of each of multiple lines, and then transfers the combined photoelectric conversion array element outputs to the signal charge detection section. A signal processing method for a solid-state imaging device according to claim (2), characterized in that when performing the above, the relative time deviation of the combined photoelectric conversion array element outputs is corrected in the opposite direction. The signal charges photoelectrically converted by the photoelectric conversion elements adjacent in the column direction in the photoelectric conversion unit array element are mixed in the vertical transfer section to output the photoelectric conversion unit array element, and then vertically transferred without operating the horizontal transfer section. The photoelectric conversion unit array element output for multiple lines is transferred from the section to the horizontal transfer section,
In this horizontal transfer section, a relative time shift is given between the outputs of the photoelectric conversion unit unit array elements of multiple lines, and the outputs of the photoelectric conversion unit array elements of each of the multiple lines are combined, and the combined photoelectric conversion unit array element outputs are combined. After transferring the array element output to the signal charge detection section, when processing the output signal of the signal charge detection section,
It is characterized by correcting the relative time deviation of the combined photoelectric conversion array element outputs in the opposite direction.

[Effect]

According to the configuration described in claim (1), a plurality of lines of photoelectric conversion unit array element outputs in which signal charges accumulated by photoelectric conversion elements adjacent in the column direction are mixed are transferred to the horizontal transfer section; After giving a relative time lag between the outputs of each photoelectric conversion unit array element of multiple lines and composing the outputs of these multiple lines of photoelectric conversion unit array elements, the combined output of the photoelectric conversion array element is horizontally transferred. When driving to transfer signal charge from the photoelectric conversion array element to the signal charge detection unit, a relative time shift is given to the photoelectric conversion array element output that has a shift among the combined photoelectric conversion array element outputs, and the shift is corrected. By this,
The positions of abnormal points in the reproduced image on the television monitor can be equalized horizontally.

According to the configuration described in claim (2), a plurality of lines of the photoelectric conversion unit array element output, which is a mixture of signal charges accumulated by photoelectric conversion elements adjacent in the column direction, is transferred to the horizontal transfer section, and the horizontal transfer section A relative time shift is given between the outputs of each photoelectric conversion unit array element of multiple lines, the outputs of each photoelectric conversion unit array element of these multiple lines are combined, and this combined photoelectric conversion array element output is transferred to the horizontal transfer section. After transferring the output signal from the signal charge detection section to the signal charge detection section, when processing the output signal of the signal charge detection section, the output signal with the deviation is given a delay in the opposite direction to the deviation, and the deviation is corrected. The positions of abnormal points in the above reproduced image can be equalized horizontally.

〔Example〕

An embodiment of the present invention will be described based on FIGS. 1 to 4.

FIG. 1 is a configuration diagram showing a solid-state imaging device.

As shown in FIG. 1, the solid-state imaging device includes a photoelectric conversion section 1 composed of a photoelectric conversion element and a color filter, and a vertical transfer section 2 that transfers signal charges of the photoelectric conversion section 1 in the vertical direction.
, a horizontal transfer section 3 that transfers the signal charges of the vertical transfer section 2 in the horizontal direction, and a signal charge detection section 4 that converts the signal charges of the horizontal transfer section 3 into signal voltages and signal currents. It is a transfer CCD.

The color filter array arranged facing each other on the photoelectric conversion unit 1 has a two-dimensional unit array of filter elements arranged in two columns and four rows! The first column of the unit array is yellow (Ye), magenta (Mg), yellow (Ye), and green (G).
The second column is constructed by repeating cyan (Cy), green (G), cyan (Cy), and magenta (Mg) in this order.

FIGS. 2(a) to 2) are diagrams showing drive timings for explaining a signal processing method of a solid-state imaging device according to an embodiment of the present invention.

In FIGS. 2(a) to (f), (a) is the composite blanking signal, (b) is the V1 clock of the four-phase clock applied to the charge transfer electrode of the vertical transfer section 2, and (C) is the composite blanking signal. is the color difference signal recognition signal (2 (Cy-Ye) when the logic level is H, L
2 (G-Mg) when , ), (c) is the Hl clock of the two-phase clock applied to the horizontal transfer section, (e) is the output signal of the signal charge detection section 4, and (f) is the TV signal. - Shows the voltage waveform of the Duyon signal.

A signal processing method for a solid-state imaging device according to an embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

During the vertical blanking period 5, the charges accumulated in the photoelectric conversion section 1 are transferred to the vertical transfer section 2 by applying a charge pulse 6 to the vertical transfer section 2.

At this time, the signal charges accumulated in two photoelectric conversion elements adjacent in the column direction among the photoelectric conversion elements of the photoelectric conversion unit 1 are mixed in the vertical transfer unit 2.

Next, during one horizontal blanking period 7 during two horizontal scanning periods,
By applying two vertical transfer pulses 8 to the vertical transfer section 2, signal charges for two lines, that is, four pixels, are transferred from the vertical transfer section 2 to the horizontal transfer section 3.

Note that one line is a collection of signal charges in the horizontal direction after mixing the signal charges accumulated by two adjacent photoelectric conversion elements.

Here, from the vertical transfer unit 2 to the horizontal transfer unit 3, the nth (n
is a real number) to the n+5th line, the n+2th line is transferred from the vertical transfer section 2 to the horizontal transfer section 3.
When transferring the signal charges of the n-th and n+3-th lines, by operating the horizontal transfer unit 3 for one additional column, the relative time for the n-th and n+3-th lines is reduced. Add a shift of one column. Thereafter, the signal charges of the (n+2)th and (n+3)th lines are combined (hereinafter referred to as a "combined line").

By processing the signals obtained in this way, the following luminance signal Y1 color difference signal C1 and color difference signal C
Get 2.

Luminance signal Y=2Ye+2G+2Mg+2Cy=2 (2
R+3G±2B) Color difference signal CI=2Ye+G+Mg (2Cy+G+M
g) =2 (Ye-Cy) Color difference signal C2=Ye+Cy+2Mg-(Ye+C31+
2G), and the brightness signal Y is normal operation (Y=2R+3G+2B
) can achieve twice the sensitivity.

That is, by mixing the signal charges accumulated by photoelectric conversion elements adjacent in the column direction and transferring the signal charges for N lines (two lines in the embodiment) to the horizontal transfer section 3 and combining them, the conventional Compared to a field storage color system based on two-pixel mixing, this method equivalently mixes 2×N pixels, so it is possible to obtain a solid-state imaging device with N times higher sensitivity characteristics.

The signal obtained by combining the n+2nd line and the n+3rd line with respect to the luminance signal Y obtained in this way has a shift of one column compared to other combined lines. Therefore, the reproduced video on the television monitor appears to be shifted by one column.

Next, a horizontal transfer pulse 9 having a frequency that can transfer the signal charge of the horizontal transfer unit 3 once in one horizontal scanning period in two horizontal scanning periods.
is applied to the horizontal transfer section 3, and a signal is output from the signal charge detection section 4.

Thereafter, a signal processing circuit (not shown) adds a delay of 0.5 bits to the output signal of the signal charge detection section 4, thereby performing correction of 0.5 columns in the opposite direction to the deviation.

3(a) to (C) are states of pixels of a solid-state imaging device to which a signal processing method for a solid-state imaging device according to an embodiment of the present invention is applied, and FIG. 4 is a solid-state imaging device according to an embodiment of the present invention. FIG. 3 is a diagram showing a reproduced image on a television monitor to which the signal processing method of FIG.

In FIGS. 3(a) to (C), (a) is the state of the pixel of the solid-state imaging device before the signal charges are combined, 忤) is the state of the pixel of the solid-state imaging device after the signal charges are combined, and ( C) shows the state of the pixels of the solid-state imaging device after the signal charges are combined and the shift by one column is corrected.

In FIGS. 3A to 3C, reference numeral 20 indicates a synthesis line of pixels to which a shift of one column has not been applied, and reference numeral 21 indicates a synthesis line of pixels to which a deviation of one column has been imparted. Further, X indicates one horizontal pixel pitch, and Y indicates one vertical pixel pitch.

Further, in FIGS. 4(a) and 4(b), 29 indicates a television monitor.

For example, when an image of a subject in the vertical direction is captured in the state of the pixels of the solid-state imaging device shown in FIG. 3(b), the reproduced image on the television monitor 29 is the reproduced image 31 shown in FIG. 4(a).
This results in abnormal points and an unsightly appearance.

Therefore, the n-th
By giving a delay of 0.5 columns in the opposite direction to this shift to the +3rd composite line 21, the result shown in Fig. 3 (C
), the deviation by one column is corrected, as shown in the (n+3)th composite line 22. As a result, television monitor 2
In the reproduced image 9, the abnormal points are equalized on the left and right, as in the reproduced image 31 shown in FIG. 4(b), making it easier to see.

Furthermore, a television signal is obtained by performing interpolation processing every other line using a storage device such as a delay line based on the output signals of the front and rear lines.

In the embodiment, a delay shift of one column is given to the output signal of the n+3rd line as a relative time shift with respect to the line, but from the nth line to the n+th line
A similar effect can be obtained if a relative time shift is given to one of the four output signals of the third line. Further, a relative time shift may be given to three output signals from the n-th line to the (n+311)-th line.

Further, in the embodiment, the signal processing circuit generates a 0.0.
By applying a delay of 5 bits, the deviation of one column was corrected, but compared to other synthesis lines, the drive of the horizontal transfer unit that applies the voltage to the synthesis line with the deviation of one column. The deviation by one column may be corrected by temporally shifting the pulse timing by 0.5 bit.

Further, in the embodiment, the number of lines to be synthesized in the horizontal transfer section 3 is two lines, but if an attempt is made to improve the sensitivity of only the luminance signal, any number of lines may be used as long as it is two or more lines. However, as the number of composite lines increases, the vertical resolution tends to decrease. Therefore, it is preferable to appropriately select the number of lines to be synthesized depending on whether emphasis is placed on sensitivity or vertical resolution.

Further, in the embodiment, the correction of the deviation by one column was performed only on the luminance signal, but it may also be performed on the color signal.

Further, the correction of the shift by one column after combining the pixels may be performed anywhere from immediately after the signal output of the imager to the television monitor.

In addition, in the embodiment, interline C is used as a solid-state image sensor.
Although a CD is used, the structure of the solid-state image sensor is not particularly limited, such as various CCDs or MOS.

In addition, in the embodiment, in the arrangement of each filter element of the color filter, the first column of the unit array of 2 columns x 4 rows is yellow (Ye).
, magenta (Mg), yellow (Ye) and green (G), and the second column is cyan (Cy), green (
G), cyan (Cy) and magenta (Mg), but the first column of the unit array of 2 columns x 4 rows is yellow (Ye).
, magenta (Mg), cyan (Cy) and magenta (Mg), and the second column may be arranged in the order of cyan (Cy), green (G), yellow (Ye) and green (G).

[Effects of the Invention] According to the solid-state imaging device driving method and signal processing method of the present invention, the photoelectric conversion unit array element output for multiple lines, which is a mixture of signal charges accumulated by photoelectric conversion elements adjacent in the column direction, is horizontally output. For example, if N947 photoelectric conversion unit array element outputs are combined by transferring them to the transfer unit and combining them, it will equivalently result in a 2XN pixel mixture, compared to the conventional field accumulation color one-type system that uses 2 pixel mixtures. , it is possible to obtain a solid-state imaging device having N times higher sensitivity characteristics.

In addition, in the horizontal transfer section, a relative time shift is given between the outputs of each photoelectric conversion unit array element of multiple lines, and after the outputs of each photoelectric conversion unit array element of these multiple lines are combined, this combined photoelectric conversion Of the array element outputs, by adding a time lag in the opposite direction to the deviated photoelectric conversion array element output to correct the deviation, the position of the abnormal point in the reproduced image on the television monitor can be determined. can be equalized left and right. As a result, it is possible to achieve higher sensitivity and reduce unnaturalness of reproduced images, thereby improving image quality.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing a solid-state image sensor, and Figures 2 (a) to (
FIG.
a) to (C) are states of pixels of a solid-state image sensor to which the signal processing method of a solid-state image sensor according to an embodiment of the present invention is applied;
Views (a) and (b) are diagrams showing reproduced images on a television monitor to which the signal processing method of the solid-state image device is applied. ■...Photoelectric conversion section, 2...Vertical transfer section, 3...Horizontal transfer section, 4...Signal charge detection section Fig. 3 (a) n line n+1 line n''2 line (b) = 2n+5 line n+5 line 1'tl JJ LJ 'O(Ll
'I-No. 4 (2I (a) (b)

Claims (2)

[Claims] (1) Four filter elements of cyan, yellow, magenta, and green are arranged in 2 columns x 2 rows. Each of the first, second, third, and fourth unit array elements is arranged in two columns x 2 rows. A color filter array consisting of an 8-row unit array; and 2 columns x 2 rows of first, second, third, and fourth photoelectric conversion unit arrays in which photoelectric conversion elements are arranged opposite to each of the filter elements. A photoelectric conversion element array of 2 columns x 8 rows in which elements are arranged in the column direction, a vertical transfer section that vertically transfers the signal charge photoelectrically converted by the photoelectric conversion element, and a vertical transfer section that transfers the signal charge of the vertical transfer section horizontally. A method for driving a solid-state imaging device comprising a horizontal transfer section that transfers signal charges to a signal charge, and a signal charge detection section that converts signal charges of the horizontal transfer section into a signal voltage and a signal current, the method comprising: in the photoelectric conversion unit array element. The signal charges photoelectrically converted by the photoelectric conversion elements adjacent to each other in the column direction are mixed in the vertical transfer section to produce a photoelectric conversion unit array element output, and then transferred to multiple lines from the vertical transfer section without operating the horizontal transfer section. transfer the photoelectric conversion unit array element outputs of minutes to the horizontal transfer section, and the horizontal transfer section applies a relative time shift between the photoelectric conversion section unit array element outputs of each of the plurality of lines, and After combining the photoelectric conversion unit array element outputs of each of the plurality of lines, when driving to transfer the combined photoelectric conversion array element outputs to the signal charge detection section, the combined photoelectric conversion array element outputs are combined. A method for driving a solid-state imaging device, comprising correcting a relative time difference in the opposite direction. (2) Four filter elements of cyan, yellow, magenta, and green are arranged in 2 columns x 2 rows. Each of the first, second, third, and fourth unit array elements is arranged in two columns x 2 rows. A color filter array consisting of an 8-row unit array; and 2 columns x 2 rows of first, second, third, and fourth photoelectric conversion unit arrays in which photoelectric conversion elements are arranged opposite to each of the filter elements. A photoelectric conversion element array of 2 columns x 8 rows in which elements are arranged in the column direction, a vertical transfer section that vertically transfers the signal charge photoelectrically converted by the photoelectric conversion element, and a vertical transfer section that transfers the signal charge of the vertical transfer section horizontally. A signal processing method for a solid-state imaging device comprising: a horizontal transfer section for transferring signal charges to a signal charge of the horizontal transfer section; and a signal charge detection section for converting signal charges of the horizontal transfer section into a signal voltage and a signal current, the method comprising: The signal charges photoelectrically converted by the photoelectric conversion elements adjacent to each other in the column direction are mixed in the vertical transfer section to produce a photoelectric conversion unit array element output. Transferring the photoelectric conversion unit array element outputs for lines to the horizontal transfer section, and applying a relative time shift between the photoelectric conversion unit array element outputs of each of the plurality of lines in the horizontal transfer section; and combining the photoelectric conversion unit array element outputs of each of the plurality of lines, transferring the combined photoelectric conversion array element output to the signal charge detection section, and then processing the output signal of the signal charge detection section. A signal processing method for a solid-state imaging device, characterized in that the relative time deviation of the combined photoelectric conversion array element outputs is corrected in the opposite direction.