JPH04326877A - Solid state image pickup device - Google Patents

Abstract

PURPOSE:To eliminate the difference of integration action time due to a position in a horizontal direction in a solid state image pickup device using a line sequential reset dot sequential readout system solid state image pickup element capable of the non-destructive read-out. CONSTITUTION:This solid state image pickup device is constituted of the solid state image pickup element provided with a picture element array 1 in which picture elements capable of being non-destructively read out are arrayed in the form of a matrix, a vertical scanning circuit 2, two horizontal scanning circuits 3,4 to scan in the directions reverse to each other and two output signal lines 5,6 to take out outputs caused by the simultaneous scanning of two scanning circuits, means 8 to A/D-convert two output signals, memories 9-1,9-2 to store two A/D-converted data of a one horizontal line portion, a control circuit 10 and an adder 11 which execute time reversal for the data reversed right and left by the reverse direction scanning and execute addition processing with the data not reversed right and left.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device using a solid-state imaging device that can be read out non-destructively.

0002

2. Description of the Related Art Conventionally, solid-state image sensors such as CMD type and AMI type are known as solid-state image sensors capable of non-destructive readout, but all of these are of a line-sequential reset point-sequential readout type. That is, the accumulated photocharges are reset in common in the horizontal direction, while the signals are read out sequentially, column by column, in the horizontal direction. The operation will be explained using FIG. 4. FIG. 4 shows a solid-state image sensor composed of a light receiving section in which unit pixels 101 are arranged in a matrix (number of horizontal pixels = m), a vertical scanning circuit 102, a horizontal scanning circuit 103, and an output signal line 104. . In the case of the line sequential reset point sequential readout method, for the row line accessed by the vertical selection line 105, the horizontal selection line 106 sequentially accesses the column line, and pixels 1, 2, 3, . . . Read operations are performed in the order of >0). When the reading of one row line is completed, the vertical selection line 105 performs a reset operation on the m pixels connected to that row line.

0003

By the way, the line-sequential reset point-sequential readout type solid-state image pickup device having the above-described configuration has a drawback that the integration time of photocharges differs depending on the pixel position in the horizontal direction. This will be explained using FIG. 5. The integral time here is defined as the time from the time when resetting is completed for a certain pixel to the time when reading is performed. Let the time when the reset is completed for a certain row line be t=0, and the first
If the pixel is read out at time t=T, then the kth pixel is read out at time t=T.
The integration time of the pixel read out (1≦k≦m) is:
It can be expressed as T+(k-1)t0. However, t0
represents the readout time of one pixel. Therefore, the integration time differs depending on the reading order, in other words, the horizontal position. Then, there is a difference in integration time of (m-1)t0 between the first pixel to be read out and the last (mth) pixel to be read out in that row line.
This is a time approximately equivalent to a 1H period.

The present invention has been made to solve the above-mentioned problems in solid-state imaging devices using a conventional line-sequential reset point-sequential readout type solid-state imaging device capable of non-destructive readout. It is an object of the present invention to provide a solid-state imaging device that does not cause the problem of different integration times.

[0005]

[Means and operations for solving the problems] In order to solve the above-mentioned problems, the present invention provides a light receiving section in which non-destructively readable pixels are arranged in a matrix, and a light receiving section for selecting row lines of the light receiving section. A vertical scanning circuit, two horizontal scanning circuits that scan in opposite directions to select the column line of the light receiving section, and for independently extracting video signals output by simultaneous scanning of the two horizontal scanning circuits. A solid-state image sensor having two output signal lines is provided as an image input section, and means for A/D converting the video signals outputted to the two output signal lines, and means for storing two A/D converted data;
A solid-state imaging device includes an adder and a control circuit for performing time reversal on left-right reversed data resulting from reverse scanning and performing addition processing with left-right unreversed data. .

In the solid-state imaging device configured as described above, a normal rotation signal is output from one output signal line, and a left/right inversion signal is output from the other output signal line. Then, for each horizontal line, these two video signals are A/D converted by the A/D conversion means and stored in the storage means, and then the horizontally inverted signal is time-inverted by an adder and a control circuit to become a normal signal. By adding, the integration time for each pixel is averaged in the horizontal direction.

[0007]

[Example] Next, an example will be explained. FIG. 1 is a block diagram showing a solid-state imaging device according to an embodiment of the present invention. In the figure, 1 is a pixel array in which non-destructively readable pixels are arranged in a matrix, and a vertical scanning circuit 2
and two horizontal scanning circuits 3 and 4. The two horizontal scanning circuits 3 and 4 operate simultaneously in opposite directions, with the first horizontal scanning circuit 3 operating from left to right in the figure, and the second horizontal scanning circuit 4 operating from right to left in the figure. Scan in the direction. Video signals output by the operations of the respective horizontal scanning circuits 3 and 4 are independently taken out by two output signal lines 5 and 6. After each of the two video signals passes through a preamplifier 7, they are converted into digital signals by an A/D converter 8 and stored in memories 9-1 and 9-2, respectively. These memories 9-1 and 9-2 are capable of storing signals for one line. A memory control circuit 10 controls the memories 9-1 and 9-2, and has a function of changing the temporal order of data taken out from one output signal line within a 1H period. The two signal data stored in the memories 9-1 and 9-2 are subjected to addition processing by an adder 11 under the control of a memory control circuit 10, and then output.

Next, the principle of correcting the difference in integration time depending on the position in the horizontal direction in the solid-state imaging device configured as described above will be explained. If the scanning direction (from left to right) of the first horizontal scanning circuit 3 is the forward direction, and the scanning direction (from right to left) of the second horizontal scanning circuit 4 is the reverse direction, then the output signal line 5
A normal normal rotation signal is outputted from the output signal line 6, and an inverted signal with the right and left sides reversed is outputted from the output signal line 6. Therefore, when the first and second horizontal scanning circuits 3 and 4 are operated simultaneously, the normal rotation signal and the inversion signal are outputted at the same time since the pixels can be read out non-destructively. This output mode is shown in Figure 2.
Shown below. That is, FIG. 2 shows the state of a normal rotation signal and an inversion signal in one line, where m is the number of horizontal pixels. In the figure, Fn (1≦n≦m) indicates the output from the nth pixel from the left in the pixel array of FIG. 1, which is output to the output signal line 5 by scanning in the forward direction. Rn indicates the output from the above pixel which is output to the output signal line 6 by scanning in the reverse direction. For the forward rotation signal (A), the outputs due to scanning in the forward direction are F1, F
2, F3, ... Fm, and in the inverted signal (B), the outputs due to scanning in the opposite direction are Rm, Rm
-1, Rm-2, . . . R1 are output in the order. Further, in this case, if m is set to an even number, one pixel will not be selected at the same time by the first and second horizontal scanning circuits 3 and 4.

The integration time of the outputs Fn and Rn will now be explained. Regarding the normal rotation signal (A) and the inversion signal (B), if the integration time of the first read signal is T, and t0 is the readout time of one pixel, then the kth (1≦k≦m) The integration time of the signal read out is T+
It is expressed as (k-1)t0. Therefore, since Fn is the nth read signal in the normal rotation signal (A), the integration time is T+(n-1)t0, and Rn
is the m-n+1th readout of the inverted signal (B), so the integration time is T+(m-n)t0
becomes. Here, the sum of Fn and Rn (Fn +Rn
) is regarded as the output from the nth pixel from the left in the pixel array of FIG. 1, then the integration time corresponding to this output is [T+(n-1)t0 ]+
[T+(m-n)t0]=2T+(m-1)t0, which is independent of n. That is, by performing the above addition process, it is possible to obtain a video signal in which the integration time does not differ depending on the position in the horizontal direction in the pixel array.

The above addition process can be easily realized in the configuration shown in FIG. 1 by simply controlling the memory addresses. Note that since the difference in integration time occurs only in the horizontal direction, the above addition process can be performed every horizontal blanking period, and the memory only needs to be one line for each of the normal rotation signal and the inversion signal. Become.

As an example of memory control, the output signal line 6
When writing the inverted signal output from the memory 9-2 into the memory 9-2,
Alternatively, when reading data from the memory 9-2, an address operation may be performed to change the order of the data, that is, to reverse the data in time. Figure 3 shows this conceptually.
It is. For example, normal rotation signals F1, F2, F3,...
Fm as #1, 2, and 2, respectively, starting from the address with the smallest address #.
3,...m, while inverted signals Rm, Rm-
1, Rm-2,... R1 are stored in #m, m-1, m-2,... 1 from the address with the largest address #, respectively, and the sum of the data with the same address # is calculated as follows: good. With such a configuration, it is possible to realize a solid-state imaging device that can display an input image on a monitor or the like in real time without causing a difference in horizontal integration time. Note that the configuration shown here shows an example for realizing the present invention, and the configuration is not limited to this configuration as long as it has a similar effect.

The present invention is based on the premise that the input/output characteristics of the elements used in the light receiving section are linear within the range of output level fluctuations due to integration time differences. Therefore, in principle,
Accurate correction cannot be made with elements that have nonlinear input/output characteristics. However, in many cases, the time required to read out one line is quite short compared to the total integration time (T≫m
t0), the output level fluctuation due to the integration time difference does not become so large. Therefore, even if an element has non-linear input/output characteristics, it can be considered to be sufficiently linear within a relatively narrow output range. It can be said that it is applicable.

Furthermore, the configuration of the above embodiment can be applied to an input device for horizontally inverted images by simply changing the memory address control circuit. That is, in the above embodiment,
Although the inverted signal is time-reversed and added to the normal signal, conversely, if the normal signal is time-reversed and added to the inverted signal, a horizontally inverted image with no horizontal integration time difference is obtained. Therefore, by changing the memory address control circuit and configuring the normal rotation signal to be time-inverted, an input device for horizontally inverted images can be obtained. Furthermore, by including a memory address control circuit that can time-reverse either the normal rotation signal or the inversion signal by external control, the image input device can obtain any image, whether it is a normal rotation image or a horizontally reversed image. It is also possible to do this.

Furthermore, the configuration of this embodiment is obviously applicable to multi-line readout as well. Furthermore, according to this embodiment, since the addition process of two frames of images is always performed, the effect of reducing random noise can also be obtained.

[0015]

[Effect of the invention] As explained above based on the embodiments,
According to the present invention, it is possible to realize a solid-state imaging device that uses a line-sequential reset point-sequential readout method and is capable of non-destructive readout, in which no difference in integration time occurs depending on the position in the horizontal direction. Furthermore, depending on the configuration of the memory control circuit, it is possible to create an image input device that can obtain any image such as a normal rotated image or a horizontally reversed image that has similar effects, and can be applied to image input devices for various purposes. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a solid-state imaging device according to the present invention.

FIG. 2 is a diagram showing the timing and integration time of output signals of the solid-state imaging device shown in FIG. 1;

FIG. 3 is a conceptual diagram showing a manner of signal addition processing by memory address control.

FIG. 4 is a schematic diagram showing a configuration example of a conventional solid-state imaging device.

FIG. 5 is a diagram showing a difference in integration time of pixels in the horizontal direction in a conventional solid-state imaging device.

[Explanation of symbols]

1 Pixel array 2 Vertical scanning circuit 3 First horizontal scanning circuit 4 Second horizontal scanning circuit 5, 6 Output signal line 9-1, 9-2 1H memory 10 Memory control circuit 11 Adder

Claims (2)

[Claims] 1. A light receiving section in which non-destructively readable pixels are arranged in a matrix; a vertical scanning circuit for selecting a row line of the light receiving section; and a vertical scanning circuit for selecting a column line of the light receiving section; A solid-state image pickup device is provided as an image input section, having two horizontal scanning circuits that perform scanning in the direction, and two output signal lines for independently extracting video signals output by simultaneous scanning of the two horizontal scanning circuits. In addition, means for A/D converting the video signals output to the two output signal lines, and an A/D converter for one horizontal line.
/D-converted data, and an adder and control unit for time-reversing the left-right inverted data by reverse scanning and adding the left-right non-inverted data to the left-right inverted data. A solid-state imaging device comprising a circuit. 2. A light receiving section in which non-destructively readable pixels are arranged in a matrix; a vertical scanning circuit for selecting a row line of the light receiving section; and a vertical scanning circuit for selecting a column line of the light receiving section; A solid-state image pickup device is provided as an image input section, having two horizontal scanning circuits that perform scanning in the direction, and two output signal lines for independently extracting video signals output by simultaneous scanning of the two horizontal scanning circuits. In addition, means for A/D converting the video signals output to the two output signal lines, and an A/D converter for one horizontal line.
/D-converted two data; an adder for time-reversing any one of the two stored data and performing addition processing with the other data; A solid-state imaging device comprising: a control circuit.