JPH0548974A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To reduce adverse influences due to the replacement of the output signal of a defective element, as to a solid state image pickup device correcting the dispersion of the respective picture elements of a solid-state image pickup element. CONSTITUTION:The addresses of defective elements 123, 125, 128, 1213 corresponding to the defective characteristic are stored in respective memories A, B, C,... of an address memory 23. A memory switching control circuit 24 selects the memory of the address memory 23 corresponding to the output signal level of the defective element, and a frame memory 21 controlled by a control circuit 22 replaces the output signal of the defective element with the output signal of an adjacent normal light receiving element in accordance with the address of the selected memory.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device for correcting variations in each pixel of a solid-state image pickup device.

In an infrared solid-state image pickup device applied as a tracking device for automatically discriminating the position and movement of a target object within an imaging visual field, if the output signal of the infrared solid-state image pickup device has a variation, the target object discrimination is performed. Therefore, signal correction processing is performed in order to correct this variation.

[0003]

2. Description of the Related Art FIG. 4 shows a block diagram of a conventional solid-state image pickup device. FIG. 4A is a block diagram of the apparatus.
(B) is a block diagram of a defective element correction processing circuit.

In FIG. 4A, a solid-state image pickup device 10 is provided.
The incident infrared light from the imaging target is condensed on the infrared detection element 12 by the condenser lens 11, and photoelectrically converted by each pixel in the solid-state imaging element 12. In this example, a two-dimensional infrared CCD (Charge Coupled Dev.
ice) is used as the solid-state image sensor 12. The output signal from the solid-state image sensor 12 is converted into digital data by the A / D converter 13 and input to the signal correction processing circuit 14.

The signal correction processing circuit 14 includes a solid-state image pickup device 1
2 (A / D converter 13) corrects the variation of the output signal, and integrates the output signal for each frame to obtain S / D.
Improve the N ratio.

The output signal corrected for variations and improved in sensitivity by the signal correction processing circuit 14 is input to the defective element correction processing circuit 15, and the output signal in which the defective element is corrected is sent to the target discrimination tracking circuit 16. As shown in FIG. 4B, the defective element correction processing circuit 15 uses the frame memory 1
7, a control circuit 18, and an address conversion memory 19.

FIG. 5 is a diagram for explaining the processing of the conventional solid-state image pickup device. FIG. 5A shows an example of the solid-state image sensor 12, and FIG.
It shows the output signal of each element corresponding to (A).

In FIG. 5, the solid-state image pickup device 12 is shown in FIG.
As shown in (A), 16 elements 12 _{1 to} 12 ₁₆ are arranged in a matrix, and the elements 12 ₃ and 12 ₅ are defective elements, and their output signals are as shown in FIG. 5 (B). To do. In this case, the element 12 ₃ shows a state where there is no sensitivity, and the element 12 ₅ shows a state where there is much noise.

Therefore, in the address conversion memory 19, the memory addresses of the elements 12 ₃ and 12 ₅ which are determined to be defective elements are replaced with the memory addresses of the adjacent normal elements 12 ₂ and 12 ₆ in advance. These memory addresses are stored as data.

Now, in the defective element correction processing circuit 15,
Address A of frame memory 17₁~ A₁₆Element 12
₁~ 12₁₆If the output signals of are stored respectively,
For example, in the address conversion memory 19, A₁, A₂, A₂，
A_Four, A₆, A₆、… A₁₆Memorize the address like
The data of the frame memory 17 is stored at the address.
read out. Thereby, the element 12₃, 12_FiveOutput signal of
Are the elements 12 ₂, 12₆Replace with the output signal of
It is something.

As described above, the defective element replacement correction process can reduce malfunctions in the target determination and tracking circuit 16.

[0012]

However, it is difficult to obtain a solid-state image sensor without a defective element at present. Therefore,
When the target object in the imaging field of view exists at the positions of the elements 12 ₃ and 12 ₅ in the above case, it cannot be found, and the found target moves to the positions of the elements 12 ₃ and 12 _5. There is a problem in that the defective element may cause an adverse effect.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a solid-state imaging device that reduces the influence of replacement of output signals of defective elements.

[0014]

SUMMARY OF THE INVENTION Among the solid-state image pickup devices in which light from an object to be imaged is received by a plurality of light receiving elements and photoelectrically converted, the output signal of an existing defective element is adjacent to the normal light receiving element. In a solid-state imaging device that replaces an output signal of an element, in accordance with the output signal of the defective element, an address storage unit having a predetermined number of memories that respectively store addresses of the defective element corresponding to defect characteristics of the defective element. Replacing the address in the memory of the address storage means selected by the memory switching means with the memory switching means for selecting the memory of the address storage means in which the defective element of the corresponding defect characteristic is stored And a control means for replacing the output signal of the defective element.

In addition, the memory switching means may appropriately respond to the incident light intensity or the output signal level of the defective element,
Selecting the memory of the address storage means, or
A signal processing unit that performs an integration process of the output signal of the light receiving element for each frame is provided, and the memory switching unit selects the memory of the address storage unit according to the frame integration in the signal processing unit.

[0016]

As described above, the address of the defective element corresponding to the defect characteristic is stored in each memory of the address storage means. Then, the memory switching means selects the memory of the address storage means according to the output signal of the defective element, and the control means outputs the output signal of the defective element to the output signal of the adjacent normal light receiving element according to the address of the selected memory. Replace with.

In other words, it is possible to replace defects according to the characteristics of defective devices of the solid-state image pickup device, and it is possible to replace the minimum required defects. As a result, it is possible to reduce the adverse effects of replacing the output signal of the defective element.

In this case, the memory switching means also makes a selection according to the incident light intensity or the output signal level of the light receiving element, and when performing frame integration, the selection is made according to the presence or absence of the frame integration or the number of integrations. It is possible to further reduce the number of defect replacements.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a block diagram of an embodiment of the present invention.
The same components as those in FIG. 4A are designated by the same reference numerals. In FIG. 1, in the solid-state imaging device 1, incident infrared light from an imaging target is photoelectrically converted by a condenser lens 11 in each light-receiving element in an infrared detection element 12 which is a solid-state imaging element. In this embodiment, 16 light receiving elements (for example, CC
D) is arranged two-dimensionally (see FIG. 2).

The output signal from the infrared detecting element 12 is A /
It is converted into digital data by the D converter 13 and input to the signal correction processing circuit 14. The signal correction processing circuit 14 is
It has a correction processing circuit for correcting variations in the output signal of each light receiving element and a signal processing means (not shown) for performing frame integration for improving the S / N ratio.

The output signal from the signal correction processing circuit 14 is input to the defective element correction processing circuit 20, and the output signal of the defective element correction processing circuit 20 is sent to the target discrimination tracking circuit 16.

The defective element correction processing circuit 20 is a control means composed of a frame memory 21 and a control circuit 22,
An address memory 23 having a plurality of memories A, B, C, ... Is an address storage means and a memory switching control circuit 24 is a memory switching means. The memory switching control circuit 24 selects the memories A, B, ... Of the address memory 23 according to the output signal level and the processing state signal from the target discrimination tracking circuit 16 or the signal correction processing circuit 14.

Now, referring to FIG.
The figure of an example of the defective element which fails to show. 2 (A) red
As described above, the outside line detection element 12 is provided for each light receiving element 12₁~
12 ₆Are arranged two-dimensionally, and the defective element 12₃，
12_Five, 12₈, 12₁₃Is a defective element.

FIG. 3 is a graph showing an example of characteristics of the infrared detecting element. Therefore, the defective elements 12 ₃ and 12
₅ , 12 ₈ and 12 ₁₃ have different defect characteristics, for example, the element 12 ₈ has no sensitivity (the output signal level does not change) when the incident light intensity I is low, and the element 12 ₁₃ is incident. There is no sensitivity when the light intensity I is high. Incidentally, the element 12 ₃ is no sensitivity throughout, element 12 ₅
Indicates that there is a lot of noise. Therefore, as shown in FIG.
The defective elements 12 ₈ and 12 ₁₃ have the same output signal as that of a normal light receiving element within the range of the incident light intensities I ₁ to I ₂ and the output signal level between V ₁ and V ₂ .

First, in the memory A of the address memory 23 in the defective element correction processing circuit 20, 4 shown in FIG.
The replacement addresses for replacing the defective elements 12 ₃ , 12 ₅ , 12 ₈ , and 12 ₁₃ at various locations are stored. The output signals of the light receiving elements 12 ₈ and 12 ₁₃ are output to the memory switching control circuit 2
4 is between the output signal levels V ₁ and V ₂ (FIG. 3), the light receiving elements 12 ₈ and 12 ₁₃ are not replaced, and
The replacement address for replacing the elements 12 ₃ and 12 ₅ shown in (B) is stored in the memory B.

In the image pickup state, for example, the element 1
When the output signal levels of 2 ₈ and 12 ₁₃ are between V ₁ and V ₂ , the memory B of the address memory 23 is selected by the memory switching control circuit 24. Then, the write address to be replaced (the adjacent element 12 ₂ ,
Address 12 ₆ ) is sent to the frame memory 21, and the read address is sent from the memory B of the address memory 23 to the frame memory 21.
The output signals of ₃ and 12 ₅ are replaced. The image signal of the infrared detecting element 12 thus subjected to the defect replacement is sent to the target discriminating and tracking circuit 16.

Thus, in the conventional case, the defective element 1
Since all the output signals of 2 ₃ , 12 ₅ , 12 ₈ , and 12 ₁₃ should be replaced, even if the elements 12 ₈ and 12 ₁₃ are defective, the number of replaced elements is reduced. Is something that can be done.

On the other hand, when the object to be imaged is distant and the moving speed is slow, the signal correction processing circuit 14 increases the number of frame integrations in order to improve the S / N ratio of the output signal. That is, when defective element 12 ₅ is noisy, the size of the noise, by increasing the frame number of integration so as to reduce the target discriminating tracking circuit 16 to occur without level malfunctions, defective elements to be replaced is element 12 Only ₃ Therefore, as shown in FIG. 2C, the replacement address is stored in the memory C so that only the element 12 ₃ is defectively replaced.

Then, the memory switching control circuit 24 uses the processing state signal of the signal tracking the distant image pickup target from the target discrimination tracking circuit 16 and the processing state signal of the signal of the number of times of frame integration from the signal correction processing circuit 14. C is selected and the same output signal replacement process as described above is performed. As a result, the number of defect replacements becomes one in this embodiment, and can be further reduced.

As described above, the defect replacement can be switched according to the image pickup operation state of the solid-state image pickup device 1 and the defect characteristic of the defective element, and the necessary minimum defect replacement can be performed.

In the above embodiment, the defect characteristics are divided into four and the memories A to C are used. However, by further subdividing and increasing the number of memories, efficient defect replacement can be performed. You can

[0032]

As described above, according to the present invention, the replacement address is stored in a plurality of memories corresponding to the defect characteristics of the defective element, and the replacement address is selected according to the output signal level and the imaging state. As a result, it is possible to perform the minimum necessary defect replacement, and reduce the adverse effects due to the defect replacement.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a defective element in an infrared detection element.

FIG. 3 is a graph showing an example of characteristics of an infrared detection element.

FIG. 4 is a block diagram of a conventional solid-state imaging device.

FIG. 5 is a diagram for explaining processing of a conventional solid-state imaging device.

[Explanation of symbols]

 1 Solid-State Imaging Device 11 Condensing Lens 12 Infrared Detector 13 A / D Converter 14 Signal Correction Processing Circuit 16 Target Discrimination Tracking Circuit 20 Defective Element Correction Processing Circuit 21 Frame Memory 22 Control Circuit 23 Address Memory 24 Memory Switching Control Circuit

Claims (3)

[Claims] 1. A plurality of light receiving elements (1) for receiving light from an imaging target.
2 _{1-12 16)} of the solid-state imaging device by receiving and photoelectrically converts (12), in the solid-state imaging device to replace the output signal of the defective elements that are present as the output signal of the normal light receiving elements adjacent the defective element The defective element (12 ₃ , 12 ₅ , 1 ₈ ) corresponding to the defect characteristic of (12 ₃ , 12 ₅ , 12 ₈ , 12 ₁₃ ).
Address storage means (23) having a predetermined number of memories (A, B, C, ...) For respectively storing addresses of 2 ₈ , 12 ₁₃ ) and defective elements (12 ₃ , 12 ₅ , 12 ₈ , 12 _13). ) Corresponding to the output signal of the defective element (1
Memory switching means (24) for selecting the memory (A, B, C, ...) Of the address storage means (23) in which 2 ₃ , 12 ₅ , 12 ₈ , 12 ₁₃ ) are stored, and the memory switching means By replacing the address in the memory (A, B, C, ...) Of the address storage means (23) selected by (24), the defective element (12 ₃ , 12 ₅ , 1) is replaced.
2 ₈ , 12 ₁₃ ) and a control means (21, 22) for replacing the output signal of the solid-state image pickup device. 2. The memory switching means (24) stores the address storage means (23) in accordance with the incident light intensity or the output signal level of the defective elements (12 ₃ , 12 ₅ , 12 ₈ , 12 ₁₃ ). The solid-state imaging device according to claim 1, wherein the memory (A, B, C, ...) Is selected. 3. A signal processing means (1) for integrating the output signals of the light receiving elements (12 _{1 to} 12 ₁₆ ) for each frame.
4) is provided, and the memory switching means (24) is provided with the signal processing means (1).
3. The solid-state imaging device according to claim 1, wherein the memory (A, B, C, ...) Of the address storage means (23) is selected according to the frame integration in 4).