JP2812457B2 - Inspection equipment for 2D imaging - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for detecting a defect in which a vertical or horizontal streak occurs in a video signal in a two-dimensional imaging device such as a CCD area sensor.

[0002]

2. Description of the Related Art A typical example of a two-dimensional imaging device is a CCD.
Area sensors. Hereinafter, a CCD area sensor will be described as an example. The CCD area sensor first transfers the output of a large number of light receiving elements arranged on the light receiving surface in a vertical and parallel manner for each line by a vertical transfer unit, and then serially and horizontally serially transfers the image signal by a horizontal transfer unit. Is what you get. For this reason, when a transfer defect occurs in the vertical transfer unit or the horizontal transfer unit, a vertical or horizontal streak occurs in the video signal, and the image quality is impaired. Therefore, in the manufacturing process of the CCD area sensor, it is necessary to efficiently and reliably detect such a defect due to a transfer defect.

A conventional CC for detecting such a transfer defect has been described.
As shown in FIG. 4, the inspection device for the D area sensor is CC
The video signal output by the D area sensor 11 is first added by the adder 12 for each line in the vertical or horizontal direction, and then the addition result of each line is subtracted by the subtracter 13 between adjacent lines. Further, the maximum value / minimum value detector 14 detects the maximum value or the minimum value of the result of the subtraction, and finally, the judgment is made by the judging device 16 to detect a defect due to a transfer defect.

That is, when a transfer defect occurs in the CCD area sensor 11, for example, as shown in FIG. 2, when the output of the CCD area sensor 11 is added line by line by the adder 12, the addition at the defective line is performed. Only the result is 90mV
, Which is a value reduced from 100 mV of the other lines. Then, when the addition result is sequentially subtracted by the adjacent ones by the subtracter 13, the subtraction result before and after the defective line becomes 10 mV and -10 mV, which are the maximum value and the minimum value of the subtraction result, respectively. Therefore, the maximum value or the minimum value is detected by the maximum value / minimum value detector 14,
The absolute value is determined by the determiner 16 to be, for example, a predetermined value of 10 mV.
By determining whether or not the above is true, it is possible to detect a defect due to a transfer defect of the CCD area sensor 11.

[0005]

However, in the CCD area sensor 11, the beating and the unevenness in which the output level gradually changes around the light receiving surface may occur. For example, in the case of the CCD area sensor 11 shown in FIG. 3, the addition result of the adder 12 tends to gradually decrease toward the right side in the figure. However, such a change in the output level gradually occurring over a plurality of lines is not caused by a transfer defect of the transfer unit and does not greatly affect the image quality. There is no need to make it bad.

However, when the CCD area sensor 11 shown in FIG. 3 is inspected by a conventional inspection apparatus, the maximum value of the output of the subtractor 13 reaches 12 mV, and the predetermined value of the decision unit 16 becomes 10 mV as described above. In this case, it is determined to be defective due to erroneous detection. Further, if the predetermined value is set to a value larger than 12 mV, the failure of the CCD area sensor 11 having the transfer defect shown in FIG. 2 cannot be detected.

As a result, the conventional inspection apparatus cannot reliably detect only a defect due to a transfer defect of the CCD area sensor, and it is necessary to visually inspect again a defect determined by this inspection. There has been a problem that the inspection efficiency is deteriorated.

In view of the above circumstances, the present invention relates to the output of each line of a two-dimensional imaging device such as a CCD area sensor.
It is an object of the present invention to provide an inspection device for a two-dimensional imaging device that can reliably detect only a defect due to a transfer defect by performing the subtraction twice.

[0009]

According to the present invention, there is provided an inspection apparatus for a two-dimensional imaging apparatus, which adds an output of the two-dimensional imaging apparatus for each line in a vertical direction or a horizontal direction, and outputs an addition result of the adder. A first subtractor for subtracting between adjacent lines,
A second subtractor for subtracting the subtraction result of the subtracter between adjacent subtraction results, and a determiner for determining whether or not the subtraction result of the second subtractor is within a predetermined range. Objective is achieved.

[0010]

In the above configuration, the addition result of the adder is CC
4 shows outputs for each line in a vertical or horizontal direction in a two-dimensional imaging device such as a D area sensor. And the first
The subtraction result of the subtractor indicates the difference between the outputs of adjacent lines, and the subtraction result of the second subtractor indicates the degree of change in the difference between the outputs.

Therefore, for example, when the output of the CCD area sensor gradually decreases for each line, the absolute value of the subtraction result of the first subtractor has a certain magnitude. Since the values are relatively close, the absolute value of the subtraction result of the second subtractor shows a small value. As a result, if a beat or unevenness in which the output level gradually changes around the light receiving surface of the CCD area sensor occurs, the second subtraction is performed even if the absolute value of the subtraction result of the first subtractor is large. Since the absolute value of the subtraction result of the unit becomes a small value, there is no possibility that the determiner erroneously determines that the defect exceeds a predetermined range.

If only the output of a specific line of the CCD area sensor is reduced, the subtraction result of the first subtractor indicates the opposite value before and after this line, and the difference between these values is calculated. The absolute value of the subtraction result of the second subtractor shown becomes an extremely large value. As a result, when a transfer defect occurs in a specific line of the CCD area sensor, even if the absolute value of the subtraction result of the first subtractor is not so large, the absolute value of the subtraction result of the second subtractor is not large. The value becomes a sufficiently large value, and the determination unit can reliably determine that the defect exceeds a predetermined range.

It is not necessary for the decision unit to make a decision on all the subtraction results of the second subtractor, and only the one with the largest absolute value in the subtraction result of the second subtractor is detected, and only this decision is made. May be performed. Also, the second
The subtractor does not need to perform subtraction on all the subtraction results of the first subtractor, detects only the one with the largest absolute value in the subtraction result of the first subtractor, and only detects the subtraction result before and after this line. Subtraction can also be performed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

FIG. 1 shows an embodiment of the present invention. The present embodiment is an inspection device for a CCD area sensor. As shown in FIG. 1, the output of the CCD area sensor 1 to be inspected is connected to the adder 2 of the inspection apparatus of the present embodiment.
The adder 2 is a circuit that adds the video signal output from the CCD area sensor 1 for each line in the vertical or horizontal direction, and outputs the addition result for each line. The output of the adder 2 is connected to the first subtractor 3. The first subtractor 3 is a circuit that subtracts the addition result of the adder 2 between adjacent lines and sequentially outputs the subtraction result. The output of the first subtractor 3 is connected to the maximum / minimum value detector 4. The maximum value / minimum value detector 4 is a circuit that detects the maximum value or the minimum value of the subtraction result of the first subtractor 3.

The output of the maximum / minimum value detector 4 is connected to a second subtractor 5. The second subtractor 5 is a circuit that performs subtraction between the maximum value or the minimum value detected by the maximum value / minimum value detector 4 and the subtraction results of the first subtractor 3 before and after the maximum value or the minimum value. The output of the second subtractor 5 is connected to the determiner 6. The determiner 6 is a circuit that determines whether the subtraction result of the second subtractor 5 is within a predetermined range, that is, whether the absolute value of the subtraction result is smaller than a predetermined value. When it is determined that the absolute value of the result of the subtraction by the second subtractor 5 is equal to or greater than a predetermined value, it is determined that the CCD area sensor 1 is defective due to a transfer defect.

The operation of the inspection apparatus having the above configuration will be described with reference to FIGS. Note that FIGS. 2 and 3
Indicates a significantly reduced number of lines for simplicity.

The addition result of the adder 2 indicates the output of the CCD area sensor 1 for each line in the vertical or horizontal direction. Accordingly, when a transfer defect occurs in the transfer section of the CCD area sensor 1, for example, as shown in FIG. 2, even though the addition result of the other lines becomes 100 mV, a uniform output is obtained. However, only the addition result of the line in which the transfer defect has occurred becomes 90 mV, and the output decreases. Although no transfer defect has occurred, the CCD
When the output of the area sensor 1 gradually decreases for each line, for example, as shown in FIG. 3, the addition result of each line also gradually decreases to 100 mV to 50 mV.

The result of the subtraction by the first subtractor 3 indicates the difference in output between adjacent lines. Therefore, in the case of FIG. 2, although the subtraction result between the other lines is 0 mV,
The result of the subtraction before and after the line where the transfer defect occurred is the opposite of 1
It becomes 0 mV and -10 mV, indicating the maximum value and the minimum value of the subtraction result. In the case of FIG. 3, the result of subtraction between the lines is the same sign and is substantially constant at 10 mV. In this case, the maximum value is 12 mV and the minimum value is 8 mV.
V is a relatively close value.

When the maximum / minimum value detector 4 detects the maximum value or the minimum value from the subtraction result of the first subtractor 3,
The second subtractor 5 performs subtraction between the maximum value or the minimum value and the subtraction results of the first subtractor 3 before and after the maximum value or the minimum value. The subtraction result of the second subtractor 5 indicates the degree of change in the difference between the outputs of the respective lines indicated by the subtraction result of the first subtractor 3. Therefore,
In the case of FIG. 2, the difference between the maximum value detected by the maximum / minimum value detector 4 and the subsequent subtraction result is 20 mV [= 10
− (− 10)], and the difference between the minimum value and the previous subtraction result is also −20 mV [= −10−10], and both have large absolute values. However, in the case of FIG. 3, the difference between the maximum value detected by the maximum / minimum value detector 4 and the previous subtraction result is 4 mV [= 12−8], and the difference between the minimum value and the subsequent subtraction result is obtained. The difference is also −4 mV [= 8−12], and both have small absolute values.

The determiner 6 determines whether or not the absolute value of the subtraction result of the second subtractor 5 is equal to or greater than a predetermined value, thereby determining a defect due to a transfer defect of the CCD area sensor 1. That is, if the predetermined value is set to less than 20 mV, the determiner 6 can reliably detect the transfer defect in the case of FIG. Unless the predetermined value of the determiner 6 is set to 4 mV or less, there is no possibility that a change in the output level due to a beat or the like shown in FIG.

As a result, according to the inspection apparatus of this embodiment,
Only by setting the predetermined value in the determiner 6 to an appropriate value between 4 mV and 20 mV, it is possible to reliably detect only the transfer defect with a margin.

[0023]

As is apparent from the above description, according to the inspection apparatus for a two-dimensional imaging device of the present invention, two subtractions are performed on the output of each line of a two-dimensional imaging device such as a CCD area sensor. Accordingly, a defect due to a transfer defect can be reliably detected by distinguishing it from a beat of the output level at the peripheral portion of the light receiving surface or the like.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which a CCD is used.
It is a block diagram of an inspection device of an area sensor.

FIG. 2 is a diagram showing each output of the inspection device when a transfer defect occurs in a CCD area sensor.

FIG. 3 shows a case where the CCD area sensor has a beat or the like.
It is a figure showing each output of an inspection device.

FIG. 4 shows a conventional example and is a block diagram of an inspection device for a CCD area sensor.

[Explanation of symbols]

 Reference Signs List 1 CCD area sensor 2 Adder 3 First subtractor 5 Second subtractor 6 Judgment device

Claims (1)

(57) [Claims] An adder for adding an output of the two-dimensional imaging device for each line in a vertical direction or a horizontal direction; a first subtractor for subtracting an addition result of the adder between adjacent lines; a first subtractor Inspection apparatus for a two-dimensional imaging apparatus, comprising: a second subtractor for subtracting the subtraction result of the second subtraction between adjacent subtraction results; and a determiner for determining whether the subtraction result of the second subtractor is within a predetermined range. .