JPH043669A - Solid-state image pickup element and image pickup signal processing circuit - Google Patents

Abstract

PURPOSE:To produce a solid-state image pickup element free from an influence of defects by providing plural photoelectric conversion parts separated from one another with one picture element as the unit. CONSTITUTION:A solid-state image pickup element 1 where plural light reception parts are collectively handled as one picture element unit is prepared. If the good result is obtained even with one light reception part in one picture element unit of the solid-state image pickup element 1, it is used together with a pickup signal processing circuit capable of compensation in the picture element unit to change the input/output characteristics to the pickup signal of a white defect compensating circuit 30 and a black defect compensating circuit 40 based on the defect condition, and the pickup signal compensated for defects is outputted, and high-quality compensation of a defective light reception part is performed. Thus, the solid-state image pickup element 1 of many picture elements free from an influence of defects is produced with a good yield.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a solid-state imaging device that is not affected by defects, and an imaging device that is suitable for processing signals of such a solid-state imaging device and that can obtain high-quality images. Related to signal processing circuits.

(Background of the Invention) Generally, defects are distributed within a silicon wafer with a certain probability. Although it is possible to reduce these defects, it is impossible to completely eliminate them. Therefore, I
When manufacturing an IC, defects will be included at a rate corresponding to the chip area of the IC. Here, since an IC made from a silicon chip containing a defect becomes a defective product, an IC having a large chip area generally has a low yield.

However, in the case of memory applications, it is possible to eliminate the effects of defects by not using the defective part and using another part instead.

Therefore, in practice, a memory IC with a capacity larger than the specified capacity is manufactured in advance and used as a spare in case of a defect. This improves the yield and reduces manufacturing costs.

(Problem to be Solved by the Invention) On the other hand, in the case of a solid-state image sensing device, it is not possible to replace it with another part such as a memory.

That is, since a solid-state image sensor converts the amount of light at each position into an electrical signal using a photoelectric conversion unit, it is impossible to replace the pixel with a pixel at another position. Therefore, if there is even one defect in one screen (hundreds of thousands of pixels), the entire solid-state image sensor is treated as a defective product. In recent years, image quality has been increasing, and as a result, the number of pixels in solid-state image sensing devices continues to increase. For this reason, the yield tends to deteriorate and the manufacturing cost tends to increase.

On the other hand, in inexpensive products using solid-state image sensors, a method is also adopted in which the signal of a defective pixel is supplemented (replaced) with the signal of a normal adjacent pixel. However, in this case, since correction is performed by necessary replacement at a specific location, deterioration in image quality at the corrected location is easily noticeable. Therefore, it cannot be used for applications that require high image quality. In general, in VTRs, etc., correction is performed to replace the signal with an adjacent signal when a dropout occurs, or in this case, the dropout and dropout occur randomly, so the correction is not noticeable.

Further, it is described in the 1983 National Television Society Newsletter, pages 101 to 102, that defects are corrected by mixing pseudo black dots with white dot flaws.

However, none of the correction methods is perfect.

The present invention has been made to solve the above-mentioned problems, and its purpose is to realize a solid-state image sensor that is not affected by defects and an image signal processing circuit suitable for such a solid-state image sensor. shall be.

(Means for Solving the Problems) A first invention for solving the above problems is a solid-state imaging device having a photoelectric conversion section and a transfer section for transferring charges generated in the photoelectric conversion section, the solid-state image sensing device comprising a plurality of separated components. A photoelectric conversion section is provided for each pixel.

A second invention for solving the above problem is an image signal processing circuit that processes an image signal output from the solid-state image sensor, wherein the defect status of each pixel of the solid-state image sensor is stored in advance. The present invention is characterized by comprising a defect information storage means, and a compensation means for performing defect compensation by changing the input/output characteristics of the imaging signal according to the defect status stored in the defect information storage means. .

(Function) In the solid-state imaging device of the present invention, charges generated in a plurality of photoelectric conversion sections are simultaneously read out in units of one pixel and output as an imaging signal.

In the image signal processing circuit of the present invention, the input/output characteristics of the compensation means for the image signal are changed based on the defect status stored in the defect information storage means, and the defect-compensated image signal is output.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an imaging signal processing circuit suitable for processing an image signal obtained by a CCDI that can handle the charges of four light receiving sections and photoelectric conversion sections as one unit.

In this figure, reference numeral 1 denotes a CCD constituting a solid-state image pickup device, which is a feature of this embodiment, and is capable of handling charges of four light receiving sections as one unit. 20
is the CC that generates drive pulses to drive the CCDI.
D drive circuit, 21 is an address generation circuit that generates an atrus (described later) using a drive pulse generated by the CCD drive circuit 20, and 22 is a defect status (white spot) for each pixel of the CCDI.
2B is a ROM in which the defect status (black spots) of each pixel of CCD 1 is stored as defect information, 30 is a white spot compensation circuit that compensates for white spot flaws, and 31 is a ROM around the CCDI. Temperature detector that detects temperature, 3
2 is a ROM that stores the relationship between temperature and defect occurrence status or temperature defect characteristics; 3B is a multiplier that multiplies the temperature defect characteristics by the defect information of each pixel; and 34 is the output of the multiplier 33 and exposure. A multiplier 35 multiplies exposure information corresponding to time, and a CC
This is a subtracter that subtracts from the DI output image signal. 40 is a black spot compensation circuit that compensates for black spots, 41 is a multiplier that multiplies the image signal by a correction value (4/3), 42 is a multiplier that multiplies the image signal by the correction value (2), and 43 is a multiplier that multiplies the image signal by the correction value (2). A multiplier 44 that multiplies the image signal by a correction value (4) is a selection circuit that selects the amount of black defect correction based on the defect information in the ROM 23. Here, the ROM 22 and the ROM 23 constitute defect information storage means, and the white flaw compensation circuit 30 and the black flaw compensation circuit 40 constitute compensation means.

FIG. 2 is a configuration diagram showing a schematic configuration of a solid-state image sensor which is a feature of this embodiment.

In this figure, 1 is a CCD that constitutes a solid-state image sensor, which is a feature of this embodiment, and it is possible to handle the charges of four light receiving sections (photoelectric conversion sections) as one unit (as a pixel unit). It is possible. 2 is a vertical transfer CCD that transfers charges in the vertical direction, 3a to 3 are vertical transfer CCs
The light receiving section is placed on the left side of D2, the light receiving section is placed on the right side of vertical transfer CCD 2 from 4a to 4, the vertical transfer CCD 5 is placed on the right side of vertical transfer CCD 2, and 6a to 6 are the left side of vertical transfer CCD 5. 7a to 7 are light receiving parts arranged on the right side of the vertical transfer CCD 5, 8 is a vertical transfer CCD that transfers charges in the vertical direction, and 9a to 9 are arranged on the left side of the vertical transfer CCD 8. The light receiving sections 10a to 10 are located on the right side of the vertical transfer CCD 8, 11 is a horizontal transfer CCD that transfers the charge from the vertical transfer section in the horizontal direction, and 12 is the charge from the horizontal transfer CCD as a voltage. This is an amplifier that outputs externally. This CCDI is characterized by having four light receiving sections around each cell of the vertical transfer section. That is, it is characterized in that the charges of the four light receiving sections existing around the vertical transfer section are treated as one.

The operation of reading from this CCDI will be explained.

In the case of frame accumulation mode, as shown in FIG. 3, vertical transfer CCDs 2d, 2h, 5d, and 5h.

The potential of 8d and 8h is lowered, and the charges of the four pixels adjacent to these are transferred.

Then, in the next field, as shown in FIG. 4, vertical transfer CCDs 2f, 2j, 5f, and 5j.

The potentials of 8f and 8j are lowered, and the charges of the four pixels in contact with them are transferred. From now on, repeat the same operation.

Here, the operation of the imaging signal processing circuit that processes the image signal read out in this way will be described.

Defects in the light receiving section of the CCDI are measured in advance for all pixels. Then, the defect information about white scratches is stored in ROM22, and the defect information about black scratches is stored in ROM22.
It is written in 3. Therefore, when driving the CCDI, the address generation circuit 21 generates an address for the light receiving section based on the drive pulse from the CCD drive circuit 20, and based on this address, the ROMs 22 and 23 output defect information of the CCDI. It has become.

White spots are defects where electric charge flows out from the light-receiving area, so
Depends on temperature and exposure time (accumulation time). Furthermore, if the outpouring is sensitive to light, it also depends on the amount of exposure. Therefore, the C detected by the temperature detector 31
The temperature around the CDI is determined by the ROM 32 to determine the amount of temperature correction based on the temperature defect characteristics, and the multiplier 33 determines the amount of correction for the defective pixel. Furthermore, based on the exposure information (information on the amount of received light calculated from the exposure time and aperture) supplied from the control unit (not shown) of the system, the amount of correction based on the exposure time and amount of exposure is calculated, and the multiplier 34 calculates the amount of correction for the defect. Find the amount of correction for the pixel. The white spot correction amount obtained in this manner is supplied to the subtracter 35, and the white spot correction amount is subtracted from the image output of the CCDI. By doing this,
It is possible to correct defects caused by white dust caused by temperature and exposure. Although subtraction was performed here, the amplification factor (
(attenuation rate) may be made variable. However, in any case,
In a broad sense, this corresponds to changing the input/output characteristics.

On the other hand, since black flaws are defects in which no charge is generated due to light reception, it is normally impossible to correct them. However, in the solid-state image sensor of this example, the four light receiving sections are one
Since it is a unit, it is possible to correct 1 to 3 defects per unit. That is, depending on the number of defects,
It can be compensated for by amplifying the signal. for example,
In the case of one pixel defect, the signal amount is reduced to 3/4, so it is sufficient to multiply by 4i3. Similarly, in the case of a two-pixel defect, the signal amount has decreased to 2/4, so it is sufficient to double the signal amount. In addition, if there are 3 pixel defects, the signal amount is 1
Since it has decreased to 74, you can multiply it by 4. Furthermore, since the possibility that all four pieces in one unit are defective is extremely small,
I can ignore it. In this case, although the total number of defects per sheet increases due to the increase in the area of the CCD, most of the defects can be compensated for, resulting in an improvement in the yield of the CCD. In addition, the total number of pixels in the light receiving section will be quadrupled, or the transfer CCD
remains the same, so the area does not quadruple.

The image output of the CCDI is supplied to a black spot compensation circuit 40 after white spots are compensated for by a white spot compensation circuit 30 .

Here, this image signal is applied to input A of the selection circuit 45. Also, multiplier 41°42.43 multiplies (4/3
The image signals multiplied by 2x, 2x, 4x) are applied to inputs B, C, and D. Here, R
Based on the defect information from OM2B, the selection circuit 44 selects and outputs a predetermined signal. That is, when there is no black space, input A is selected. Furthermore, if there is a black spot, inputs B, C, and D are selected depending on the amount of the scratch. By doing this, it becomes possible to compensate for black spots in the case of pigeons.

In this explanation, compensation for white scratches and compensation for black scratches was performed, but compensation for only one or the other may be performed.

By the way, although the frame accumulation mode has been explained in FIGS. 3 and 4, other driving modes are also possible.

In the field accumulation mode, after all pixels are read out, the combinations are changed depending on the field, the charges are mixed, and the charges are read out. That is, as shown in FIG. 5, vertical transfer CCDs 2b and 2d.

2f, 2h, 2j, 5b, 5d, 5f, 5h, 5j, 8
The potentials of b, 8d, 8f, 8h, and 8j are lowered, and the charges (total charges) of the four light receiving parts in contact with these are transferred. Here, 2a, 2b, 2e2f, 2i, 2L 5a, 5b
, 5e, 5f, 5i, 5L 8a, 8b, 8e, 8f,
The potentials of 8i and 8J are increased and the charges are mixed. Then, the charges are read out. In the next field, as shown in FIG.
2d, 2f, 2h, 2j, 5b,
5d, 5f.

The potentials of 5h, 5j, 8b, 8d, 8f, 8h, and 8j are lowered, and the charges (total charges) of the four pixels in contact with these are transferred. And 2c, 2d, 2g.

2h, 5c, 5d, 5g, 5h, 8c, 8d, 8g, 8
Increase the potential of h and mix the charges. Then, the charges are read out.

Furthermore, the above explanation is for a case where reading is performed in accordance with the format of a television signal. However, in addition to this, non-interlaced reading is also possible. For example, by driving a vertical transfer CCD in two phases,
It reads out the signal. In this case, it becomes possible to use it for various applications such as high-definition image reading.

Furthermore, as shown in FIGS. 7 and 8, if the combinations of four pixels are shifted, the resulting shift will be 1/2 pixel, so the resolution in the vertical direction will be improved.

In the above description of the imaging signal processing circuit, a CCD is used as the combined solid-state imaging device, but the present invention is not limited to this. That is, it is also possible to obtain high-quality images with the imaging signal processing circuit shown in FIG. 1 using the MO3 type image sensor.

In this case, similar effects can be achieved by switching the photodiodes of multiple pixels of the MO3 type image sensor at the same time. Also, if you do not turn on the switch when scanning white spots, the problem will disappear.

Further, not only a two-dimensional solid-state image sensor but also a one-dimensional solid-state image sensor can provide the same effects as described above.

As explained in detail above, a solid-state image sensor is prepared in which multiple light-receiving sections are treated as one pixel unit, and even one light-receiving section within one pixel unit of such a solid-state image sensor is satisfactory. By using it together with an imaging signal processing circuit that can perform compensation within each pixel, if available, the yield of solid-state imaging devices can be dramatically improved. Furthermore, although the number of pixels in the light receiving section increases, the transfer section remains the same as before, so the overall area of the chip does not increase significantly, contributing to improved yield.

Further, since the compensation for the defective light receiving portion is performed within the same pixel unit, the compensation is of higher quality than the conventional one. Furthermore, even better images can be obtained by changing the amount of compensation depending on the temperature and exposure time. As a result, it is possible to manufacture a multi-pixel solid-state imaging device with a high yield, which has been difficult in the past, and it is also possible to obtain high-quality images.

(Effects of the Invention) As described above in detail, in the present invention, a solid-state image sensor is prepared in which a plurality of pixels of a photoelectric conversion section are collectively treated as one pixel unit, and one pixel unit of such a solid-state image sensor is If even one of them is good, the yield of solid-state image sensors can be dramatically improved by using them together with an imaging signal processing circuit that can perform compensation within each pixel. Furthermore, although the number of pixels in the light receiving section increases, the transfer section remains the same as before, so the overall area of the chip does not increase significantly, contributing to improved yield.

Further, since the compensation for the defective light receiving portion is performed within the same pixel unit, the compensation is of higher quality than the conventional one. Furthermore, even better images can be obtained by changing the amount of compensation depending on the temperature and exposure time. As a result, it is possible to manufacture a multi-pixel solid-state imaging device with a high yield, which has been difficult in the past, and it is also possible to obtain an imaging signal processing circuit that can obtain high-quality images.

[Brief explanation of drawings]

1 is a block diagram showing the configuration of an imaging signal processing circuit according to an embodiment of the present invention; FIG. 2 is a diagram showing an example of a solid-state image sensor used in the imaging signal processing circuit shown in FIG. 1; The figure is an explanatory diagram showing an example of the operation of the solid-state image sensor used in the image signal processing circuit shown in Fig. 1 in frame accumulation mode. Figure 4 is the solid-state image sensor used in the image signal processing circuit shown in Fig. 1. FIG. 5 is an explanatory diagram showing an example of the operation of the field accumulation mode of the solid-state image sensor used in the imaging signal processing circuit shown in FIG. 1, and FIG. An explanatory diagram showing an example of the operation of the solid-state image sensor used in the image signal processing circuit shown in the figure in the field accumulation mode. FIG. 8 is an explanatory diagram showing an example of operation in another mode of the solid-state image sensor used in the imaging signal processing circuit shown in FIG. 1... CCD 20... CCD drive circuit 21... Address generation circuit 2223... ROM 30... White stain compensation circuit 31... Temperature detector 32... ROM33...
Multiplier 34... Multiplier 35... Subtractor
40...Black flaw compensation circuit 41.42.43.
... Multiplier 44 ... Selection circuit

Claims (2)

[Claims] (1) A solid-state imaging device having a photoelectric conversion section and a transfer section for transferring charges generated in the photoelectric conversion section, characterized in that a plurality of mutually separated photoelectric conversion sections are provided for each pixel. Image sensor. (2) An image signal processing circuit for processing an image signal output from the solid-state image sensor according to claim 1, comprising a defect information storage in which defect status of each pixel of the solid-state image sensor according to claim 1 is stored in advance. and compensation means for performing defect compensation by changing the input/output characteristics of the imaging signal according to the defect status stored in the defect information storage means.