JPH1023339A - Solid-state image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To replace a false signal with a normal picture element signal by introducing a simple modification to a charge storage section of a solid-state image pickup element and an optical system of the solid-state image pickup device to detect the false signal due to defective picture elements caused at random in operation. SOLUTION: The device moves a visual image formed by a scanner 12 and a scanner control section 18 by one picture element in the scanning direction, and a signal detection section 14 detects signals whose level is a threshold level or over set from a signal subject to photoelectric conversion in an image area 13. A delay circuit 15 delays an output of a frame generated from the signal detection section by one frame. Then a comparison replacement circuit 16 compares an output from the delay circuit 15 with an output of a succeeding frame and on the occurrence of a defective picture element, the circuit 16 replaces the defective data with data of a succeeding frame. An address conversion section 17 converts an address at an output of the succeeding frame to match the picture element position of the output with the output of the preceding frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a one-dimensional solid-state imaging device suitable as a photoelectric conversion unit of a tracking device for a point target which targets a high-speed object.

At present, in order to improve the performance of a tracking device, the number of pixels and the pixel size of a solid-state image pickup device are increased with the aim of improving spatial resolution, and the chip size tends to increase.

Along with the above, in a photoelectric conversion unit formed on a semiconductor substrate, unlike a defect that can be found by an initial inspection in a manufacturing process, such as a pattern defect,
Due to the existence of traps due to minute defects inside the crystal, pixel defects occur during operation due to temporal factors.

[0004] Such a pixel defect causes a serious problem of erroneous recognition in the tracking device. Therefore, even during operation, the occurrence of the defect can be detected and a normal signal can be output. The realization of such a solid-state imaging device having high reliability is expected, and the present invention can provide one means for meeting the demand.

[0005]

2. Description of the Related Art Generally, a CCD (charge cue) is used.
In a solid-state imaging device using a pleated device, various means are employed to correct a pixel defect.

FIG. 5 is a main block diagram showing an example of a conventional solid-state imaging device having a function of correcting a pixel defect.
It should be noted that JP-A-56-140790 may be specifically referred to.

In the figure, 1 is a lens, 2 is a solid-state image sensor, 3 is an A / D converter, 4 is a frame memory, 5 is a defect registration ROM (read only memory),
Reference numeral 6 denotes a defective pixel determination circuit.

In this solid-state imaging device, a defective pixel is specified in advance at the time of product shipment, and its position information is registered in a ROM or the like, and during operation, based on the position information of the defective pixel,
The signal of the defective pixel is replaced with the signal of another normal pixel.

However, since the color filters of each pixel in the solid-state imaging device 2 are arranged with a predetermined repetition period in the horizontal direction, the signal of the normal pixel to be replaced is the signal of the pixel adjacent to the defective pixel. Cannot be selected, and considering the repetition period, close to the defective pixel,
In addition, the pixel signals having the same color filter are replaced with the signals.

In addition to the solid-state imaging device described above, a photoelectric conversion element and a C for transferring a signal from each pixel are provided.
There are provided a CD register, a memory register arranged in parallel with the CCD register, and the same number of charge injection sections corresponding to each pixel in the photoelectric conversion element for injecting charge into the memory register. Also, a solid-state imaging device is known (see Japanese Patent Application Laid-Open No. 58-96466 if necessary).

In this solid-state imaging device, the wiring between the pixel having an image defect and the CCD register is cut by a laser or the like, and the memory charge injected into the memory register is injected into the CCD register. This corrects the defect.

[0012]

As shown in FIG. 5, in an image pickup device conventionally used in a tracking device, a fixed visual field image limited by an optical system is formed on a two-dimensional solid-state image pickup device. Then, the electric signal is read out to an external signal processing system, and image data for two to three frames is stored in the frame memory 4.
Among the data in the memory 4, data corresponding to the defective pixel position registered in the defect registration ROM 5 corresponds to a color filter provided in the solid-state imaging device 2 with a predetermined repetition cycle in the horizontal direction. The target is detected after performing defect correction by replacing the signal with the pixel signal.

FIG. 6 is a diagram showing a DC component in the output of a normal pixel and a defective pixel. The horizontal axis represents a frame, and the vertical axis represents a DC level in arbitrary units.

As is apparent from the figure, some pixel defects repeatedly occur and disappear randomly over several frames.
The above-described conventional technique cannot cope with such a problem, and in actual operation, such a random pixel defect is 1
In a tracking device targeting a high-speed moving object that needs to detect a pixel-sized point target,
This will cause misrecognition.

According to the present invention, a simple modification is made to a charge storage portion of a solid-state imaging device and a simple modification is introduced to an optical system of a solid-state imaging device to detect a false signal due to a pixel defect generated during operation. , It is possible to reliably replace the false signal with a signal of a normal pixel.

[0016]

FIG. 1 is a block diagram showing a main part of a solid-state imaging device for explaining the principle of the present invention.

In the drawing, 11 is a condenser lens, 12 is a scanner, 13 is an image area, 14 is a signal detector,
15 is a delay circuit, 16 is a comparison / replacement circuit, 17 is an address converter, 18 is a scanner controller, T1 and T2
Indicates output terminals.

The scanner 12 shown in FIG. 1 controls an optical path from the condenser lens 11 to the image area 13 by the scanner controller 1.
Under the control by the control unit 8, the pixel moves in the horizontal direction by one pixel.

Similarly, the signal detecting section 14 functions to detect a signal having a threshold value or more from a signal obtained by photoelectrically converting the image area 13.

Similarly, the delay circuit 15 includes a signal detector 14
When the signal detection is performed in step (1), the output of the frame in which the signal is generated is delayed by one frame.

Similarly, the comparison / replacement circuit 16 compares the output of the delay circuit 15 with the output of the next frame, and if there is a pixel defect, replaces the output with the data of the next frame.

Similarly, the address conversion unit 17 functions to match the address at the output of the next frame with the output of the previous frame at the pixel position.

FIG. 2 is an explanatory view of a main part showing an image output area for explaining the operation of the solid-state imaging device shown in FIG.

Now, assuming that the image is captured under a fixed background, if the signal of the pixel portion at the position (i, j) at the Kth frame which is the output at the output terminal T1 increases,
The signal detector 14 detects this signal change and delays the output to the external signal processing circuit by one frame by the operation of the delay circuit 15.

In the (K + 1) th frame, the scanner controller 1
The field of view image is changed to 1 by the action of the scanner 13 controlled by the control unit 8.
The pixel moves in the horizontal direction by the number of pixels, and at the K-th frame, (i,
The image in the pixel section of (j) is input to the pixel section of (i + 1, j), and the signal is output from the output terminal T2. The signal is input to the comparison / replacement circuit 16 together with the signal of the Kth frame delayed by one frame in the circuit 15.

Since the frame period is at least 30 [Hz] at the latest, it can be considered that the field images of the Kth frame and the (K + 1) th frame hardly change, and the signal of the Kth frame is a signal from a true object. If the signal is a signal, the signal from the pixel portion at (i, j) in the K-th frame is compared with the signal (i +
The signal from the pixel section of (1, j) should be almost the same.

However, if the signal from the pixel portion at (i, j) in the K-th frame is a false signal composed of suddenly generated random noise as shown in FIG. Since the signal of the pixel portion of (j) is different from the signal of the pixel portion of (i + 1, j) of the (K + 1) -th frame, the pixel of (i, j) of the K-th frame depends on the operation of the comparison / replacement circuit 16. The signal from the unit is replaced with the signal from the pixel unit at (i + 1, j) in the (K + 1) th frame, and then output to the external signal processing circuit.

As described above, in the solid-state imaging device according to the present invention, (1) an optical lens system (for example, a condenser lens 11: see FIG. 1) for condensing a visual field image and a light receiving element (for example, Between the image area (for example, the image area 13: see FIG. 1) composed of a pixel portion (for example, the pixel portions 21, 22,..., Etc .: see FIG. 3) including the photodiode D1: see FIG. Operation means (for example, scanner 12, scanner control unit 18, etc .: see FIG. 1) for moving the field of view image formed on the light receiving element by one pixel in the scanning direction and two adjacent pixel units Comparing means for comparing signals of substantially the same field of view image to determine whether the signal is a true signal from an object in the field of view or a false signal due to a pixel defect randomly generated during operation. For example, comparison / replacement circuit 1
6: refer to FIG. 1), or

(2) In the above (1), each pixel section has two charge accumulation sections (eg, charge accumulation sections C1 and C1) for accumulating signal charges of different frames or different fields.
2: two analog amplifiers (eg, amplifiers A1 and A2: see FIG. 4) corresponding to the two charge storage units, and one of the two charge storage units is a signal of a certain frame or a certain field. The other charge accumulating portion accumulates electric charges, and when the signal of a certain frame or a certain field related to a certain visual field in an adjacent pixel portion exceeds a set threshold value, the signal of the next frame or the next field related to substantially the same visual field Characterized by accumulating charge, or

(3) In the above (1), the comparing means compares the signals from the analog amplifiers in the two adjacent pixel units, which are shifted by one frame or one field, with respect to substantially the same field of view by analog values. It is characterized in that the signal is to determine whether the signal is a true signal from the object in the field of view or a fake signal due to a pixel defect randomly generated during operation, or

(4) In the above (1), the image area (for example, image area 13: see FIG. 1) has n columns × m rows (n and m are the number of pixel units required by the system). In the case of (natural number), pixel units of (n + 1) columns × m rows are provided, and each frame or each field depends on the optical lens operating means (for example, the scanner 12, the scanner controller 18, etc .: see FIG. 1). A comparison / replacement circuit, which is a comparison means, in order that the image signals of n columns × m rows are sequentially compared when there is no tracking target in the image signal. (E.g., a comparison / replacement circuit 16: see FIG. 1) and sent to an external signal processing circuit.

(5) In the above (1), the comparison / replacement circuit (for example, the comparison / replacement circuit 1
6: see FIG. 1) is a signal detection unit (for example, the signal detection unit 14:
When an image signal exceeding a set threshold value from an image area (for example, image area 13: see FIG. 1) is detected, a delay circuit (for example, delay circuit 15: FIG. 1) is detected.
If the image signal is a false signal due to a pixel defect that has occurred randomly during operation, the image signal is compared with the output of the next frame or field that is substantially the same field of view information as the image signal delayed in step (1). It is characterized in that it is replaced with an image signal which is output of the next frame or field which is substantially the same visual field information and is sent to an external signal processing circuit.

By employing the above means, when a false signal is generated due to a pixel defect generated during the operation of the solid-state imaging device, it is surely detected that the signal is false, and the detected signal is detected as a normal pixel. Can be replaced by
Even in a high-speed object tracking device that must capture a pixel-sized object, false recognition can be reduced, and signals from pixels that generate random noise are not output. As a result, an increase in noise can be suppressed.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 is a block diagram of a main part for explaining an embodiment of a solid-state imaging device according to the present invention.
Note that the same symbols as those used in FIG. 1 represent the same parts or have the same meaning.

In the figure, 21 to 24 and 31 to 3
Reference numeral 4 denotes a pixel portion, 41 denotes a horizontal shift register, 42 denotes a vertical shift register, and T denotes an output terminal.

The number of pixel units is determined by the image area 13 (FIG. 1).
The number of light-receiving elements consisting of photodiodes in
Alternatively, it may be considered that the number of pixel electrodes is such that the number of pixel units required for the system is n columns × m rows (n,
m is a natural number), whereas (n + 1)
Columns × m rows are arranged.

FIG. 4 is a main part circuit diagram for explaining the specific configuration of one pixel portion. The pixel portions 21 to 24 and the inside 34 of FIG. 3 all have the same configuration.

In the figure, M11, M12, M13, M
21, M22, and M23 are transistors, and D1 is a photo transistor.
Diodes, C1 and C2 are charge storage units, A1 and A2
Denotes amplifiers, respectively.

While the transistor M11 controlled by the F selection signal indicating the lens position and the integration time control pulse is on, the signal charge photoelectrically converted by the photodiode D1 is stored in the charge storage section C1. Charge-voltage conversion is performed.

In this state, the transistor M13 controlled by the selection pulse from the vertical shift register 42 and the F selection signal is turned on, thereby reading out the signal of the voltage of the amplifier A1 to the signal detector 14.

Here, when there is no change in the field of view, the signal passes through the comparison / replacement circuit 16 from the signal detection unit 14, and is sequentially selected from the output terminal T by the selection pulse by the horizontal shift register 41 from the external signal processing device. Is read to.
At this time, the feedback signal from the signal detector 14 does not change.

After repeating the above operation for one frame or one field, the reset pulse and the signal
By supplying a control pulse based on the feedback signal from the reset transistor M12 to the charge storage section C12
The signal charge stored in 1 is reset and the same reading is performed.

Now, when the signal at a certain pixel portion increases,
The signal detector 14 detects an increase in the signal, and the signal detector 14
The supply of the reset pulse in the current frame is stopped in response to the feedback signal from the CPU, and the signal charge according to the current frame is held in the charge storage unit C1.

In the next frame, the lens operation is performed,
The visual field image is moved by one pixel in the horizontal direction, and the visual field image existing in the pixel unit 21 in the previous frame enters the pixel unit 22.

In the pixel section 22, the transistor M21 is controlled by the F selection signal and the integration time control pulse.
Is turned on, the signal charge of the photodiode D1 in the pixel unit 22 is stored in the charge storage unit C2, and the charge is converted into a voltage by the amplifier A2.

The voltage of the amplifier A2 is turned on by turning on the transistor M23 controlled by the selection pulse from the vertical shift register 42 and the F selection signal.
4 and read out to the comparison / replacement circuit 16.

At the same time, in the pixel section 21, the transistor M13 is turned on, and the charge storage section C is turned on.
The signal charge of the previous frame held by 1 is read out again via the amplifier A1 and compared with the charge voltage from the amplifier A2 of the pixel section 22 in the comparison / replacement circuit 16.

Normally, the frame period is 30 [H] at the latest.
z] or more, the field images of the Kth frame and the (K + 1) th frame may be almost unchanged.

If the increase in the signal is due to random noise generated during the operation, the signals of the K-th frame and the K + 1-th frame are different from each other. By replacing the data with the data of the corresponding pixel unit 22 and outputting the data, only a normal signal is output.

[0050]

In the solid-state imaging device according to the present invention,
It is installed between the optical lens system for condensing the visual field image and the image area consisting of the pixel section including the light receiving element, and moves the visual field image formed on the light receiving element by one pixel in the scanning direction. The operation means compares signals of substantially the same visual field image in two adjacent pixel portions and determines whether the signal is a true signal from an object in the visual field or a false signal due to a pixel defect randomly generated during operation. And a comparing means for determining whether the signal is a signal of

According to the above configuration, when a false signal is generated due to a pixel defect generated during the operation of the solid-state imaging device, it is reliably detected that the signal is false, and the false signal is detected. Can be replaced by
Even in a high-speed object tracking device that needs to capture a pixel-sized object, false recognition can be reduced, and signals from pixels that generate random noise are not output. As a result, an increase in noise can be suppressed.

[Brief description of the drawings]

FIG. 1 is a principal block diagram showing a solid-state imaging device for explaining the principle of the present invention.

FIG. 2 is an explanatory view of a main part showing an image output area for explaining an operation of the solid-state imaging device shown in FIG. 1;

FIG. 3 is a main part block diagram for describing an embodiment of a solid-state imaging device according to the present invention.

FIG. 4 is a main part circuit diagram for explaining a specific configuration for one pixel.

FIG. 5 is a main block diagram illustrating an example of a conventional solid-state imaging device having a function of correcting a pixel defect.

FIG. 6 is a diagram showing DC components in outputs of a normal pixel and a defective pixel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Condenser lens 12 Scanner 13 Image area 14 Signal detection part 15 Delay circuit 16 Comparison / replacement circuit 17 Address conversion part 18 Scanner control part T1 and T2 Output terminal 21-24 Pixel part 31-34 Pixel part 41 Horizontal shift register 42 Vertical shift register T Output terminal M11, M12, M13 Transistor M21, M22, M23 Transistor D1 Photodiode C1 and C2 Charge storage unit A1 and A2 Amplifier

Claims (5)

[Claims] 1. A field-of-view image formed on a light-receiving element, which is provided between an optical lens system for converging a field-of-view image and an image area including a pixel section including a light-receiving element, is formed by one pixel in a scanning direction. The operation means for moving by the distance and signals of substantially the same visual field image in two adjacent pixel portions are compared, and the signal is a true signal from an object in the visual field and randomly generated during operation. And a comparing means for determining whether the signal is a false signal due to a pixel defect. 2. Each pixel section has two charge storage sections for storing signal charges of different frames or different fields, and two analog amplifiers corresponding to the two charge storage sections, and one of the two charge storage sections. The signal charge of a certain frame or a certain field is accumulated, and the other charge accumulating portion is connected to the next pixel of a substantially same visual field when a signal of a certain frame or a certain field in an adjacent pixel portion exceeds a set threshold value. 2. The solid-state imaging device according to claim 1, wherein signal charges of a next frame or a next field are stored. 3. The comparison means compares the signals from the analog amplifiers in two adjacent pixel units, which are shifted by one frame or one field, with respect to the substantially same field of view by analog values, and determines whether the signals are from an object within the field of view. 2. The solid-state imaging device according to claim 1, wherein the solid-state imaging device determines whether the signal is a true signal or a false signal due to a pixel defect randomly generated during operation. 4. An image area is provided with (n + 1) columns × m rows of pixel units when the number of pixel units required by the system is n columns × m rows (n and m are natural numbers). And a configuration in which two or more adjacent pixel portions can form substantially the same visual field by the optical lens operating means for each frame or each field, and when no tracking target exists in the image signal, n columns × The image signals of the m-th row are sequentially compared by comparison means
2. The solid-state imaging device according to claim 1, wherein the signal is transmitted to an external signal processing circuit via a replacement circuit. 5. A comparison / replacement circuit included in the comparison means, wherein when the signal detection section detects an image signal equal to or larger than a set threshold value from the image area, the field of view is substantially the same as the image signal delayed by the delay circuit. If the image signal is a fake signal due to a pixel defect that has occurred randomly during operation as compared with the output of the next frame or field that is information, the next frame or field that is substantially the same field of view information 2. The solid-state imaging device according to claim 1, wherein the image signal is output to an external signal processing circuit in place of an output image signal.