JPH09101268A - Defect inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly inspect an object to be inspected for printing defects by forming different windows so that the windows do not cross a boundary. SOLUTION: When a start signal h1 is inputted to a plane forming/ discriminating circuit 61 for first plane, the circuit 61 receives defectless picture data and the picture elements h3 to be inspected of data picture data to be inspected based on the synchronism of an operation clock h2, inspects the gradation levels of the picture elements of both data for difference, increments the counter of each window whenever the difference is found, and, when the count value becomes larger than a reference value, discriminates that an object to be inspected has a printing defect. When the inspection is completed to prescribed picture elements in the Y- and X-axis direction, the circuit 61 outputs output signals h4 and h5 to second and third plane forming/discriminating circuits 61 and 61 so as to form second and third planes which are deviated from the first plane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection apparatus, and more particularly to a defect inspection apparatus which divides inspection image data of an object to be inspected into a plurality of windows and determines the presence or absence of a defect in window units.

[0002]

2. Description of the Related Art A conventional defect inspection apparatus, for example, as shown in FIG. 6, when inspecting an object for defects,
The non-defective image data of the printed matter, which is a good product having 1024 × 1024 pixels, and the inspection image data of the printed matter, which is the inspection object, are divided into a plurality of small windows each having 128 × 128 pixels, and the divided windows are used as a unit. The presence or absence of a printing defect is determined based on the number of defective pixels contained therein.

That is, in a conventional defect inspection apparatus, as shown in FIG. 7, non-defective image data recorded in an image memory and inspection image data of an object to be inspected are input to a comparator 71 incorporated in the apparatus. From the scan start location,
The gradation levels are compared for each pixel.

Subsequently, in the inspection apparatus, every time a difference of a predetermined gradation level or more is detected as a result of comparison by the comparator 71, the counter 72 counts for each predetermined window, and the count value and the print defect are counted. The comparator 73 incorporated in the apparatus compares the reference value that is determined to be the above. If the count value is larger than the reference value, it is determined that the inspection target object is defective in printing. .

[0005]

However, in such a conventional defect inspection apparatus, when there is a print defect extending over the window boundary, even if the print defect is larger than the reference value, the window Since the size of the print defect becomes smaller than the reference value in units, there is a problem that what should originally be a print defect may not be determined as a print defect.

For example, as shown in FIG. 8, when the conventional defect inspecting apparatus determines that there are 20 reference values which are judged to be print defects, the print defect A is 22 within the window 1 which is larger than the reference value 20. Since it has a defective pixel, it is clearly determined to be a printing defect.

The print defect B has 35 defective pixels as a whole, but since there are 17 defective pixels and 17 defective pixels in the window 1 and the window 2, respectively, the original defect is present. It is determined that what should be a defect is not a defect.

The print defect C has 70 defective pixels. However, since defective pixels having a reference value less than 20 are present in each of window 1, window 2, window 3 and window 4, it is originally intended. It is judged that what should be a defect is not a defect.

Therefore, if the number of defects in the window is checked by shifting the window pixel by pixel, the above problem can be solved, but a new problem that a huge processing time is taken occurs.

In view of the above problems, it is an object of the present invention to provide a defect device for promptly inspecting print defects.

[0011]

In order to achieve the above object, the invention according to claim 1 divides inspection image data of an object to be inspected into a plurality of windows into one plane, and a window unit constitutes a plane. In the defect inspection apparatus for determining the presence or absence of a defect, the plane has a plane setting means for setting a plurality of planes having mutually shifted windows for the same inspection image data, and the same inspection image data is based on the plurality of planes. It is characterized by making a judgment.

According to a second aspect of the present invention, in the first aspect of the invention, the presence or absence of defects in the plurality of planes set by the plane setting means is determined simultaneously in parallel.

According to a third aspect of the present invention, in the first aspect of the invention, the window is composed of a plurality of pixels arranged on a grid in the X and Y axis directions, and the plane setting means is a window to be inspected. Is set in the X and Y axis directions by a predetermined number of pixels to set a plurality of planes having windows that are offset from each other.

According to a fourth aspect of the invention, in the third aspect of the invention, the plane setting means has a raster scan collecting means for sequentially collecting the inspection image data of the inspection object along the X-axis direction. , The first plane setting means for dividing the inspection image data into a plurality of windows based on the position of the initially collected inspection image data, and setting the reference plane, and the first plane setting means. While scanning the plane, the scan position of the inspection image data is X from the position of the inspection image data that was first acquired.
When the position is shifted by a predetermined number of pixels in the axial direction, the inspection image data is divided into a plurality of windows with the position as a reference,
Second plane setting means for setting a plane such that each window is located at a position shifted by a predetermined number of pixels in the X-axis direction from the window position set by the first plane setting means, and the first plane setting means While scanning the plane set by, when the scan position of the inspection image data comes to a position shifted by a predetermined pixel in the Y-axis direction from the position of the inspection image data initially collected, the inspection image data is set with the position as a reference. Third plane setting means for dividing the window into a plurality of windows and setting the plane so that each window is located at a position shifted by a predetermined number of pixels in the Y-axis direction from the window position set by the first plane setting means; While scanning the plane set by the third plane setting means, the scan position of the inspection image data is predetermined in the X-axis direction from the first reference position. When the position is shifted to a prime position, the inspection image data is divided into a plurality of windows on the basis of the position, and the position is shifted from the window position set by the third plane setting means by a predetermined pixel in the X-axis direction. And a fourth plane setting means for setting a plane so that each window is present.

The invention according to claim 5 is the same as claims 3 and 4.
In the invention described above, the shift amount of the pixels is half the number of pixels constituting the window in both the X and Y axis directions.

According to the present invention, the plane setting means sets a plurality of planes having windows that are offset from each other for the same inspection image data, and judges the same inspection image data based on the plurality of planes. Even if they exist on the boundary,
It can be unbounded in any other window.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the defect inspection apparatus according to the present invention will be described below with reference to the drawings. First, description will be given of the contents on which the defect inspection apparatus according to the present invention is based.

In the defect inspection apparatus of this embodiment, as shown in FIG. 1, one piece of non-defective image data of 1024 × 1024 pixels and one piece of inspection image data of the inspection object are provided.
The window is divided into windows of 28 × 128 pixels, the gradation levels of the pixels in the windows are compared for each of the divided windows, and when the number of pixels having a difference in gradation level is equal to or more than a reference value, The object to be inspected is judged to be defective in printing.

Moreover, the defect inspection apparatus of this embodiment is
As shown in FIG. 1A, the scan start position is a window (64) from the first pixel (1, 1) of the inspection image data (see black circles in the figure) to the last scan pixel (1024, 1024). The print defect is determined in # 1 to # 64), and the scan start position is determined as shown in FIG.
A window (#) obtained by dividing the last scan pixel (1024, 960) into 56 pieces from the pixel (1, 65) (see the black circle in the figure) at a position shifted by 1/2 window in the X-axis direction compared to (a). 1 to # 56) to judge the printing defect,
As shown in (c), the scan start position is shifted from the pixel (65, 1) (see the black circle in the figure) at the position shifted by 1/2 window in the Y-axis direction from the last scan pixel ( 960, 1024) are divided into 56 windows (# 1 to # 56) to determine a print defect, and then, as shown in FIG.
Pixels (65, 65) at positions where the scan start position is shifted by 1/2 window in the X-axis direction and 1/2 window in the Y-axis direction as shown in FIG. 1A (see black circles in the figure). From the last scan pixel (960,960) to 4
A print defect is determined by windows (# 1 to # 49) divided into nine windows. And the defect inspection apparatus of this embodiment is
When the number of differences in gradation level is equal to or larger than the reference value in any one of these windows, it is determined that the printed matter that is the inspection object has a print defect.

Here, the inspection image data obtained by dividing the inspection image data into 64 windows (# 1 to # 64) as shown in FIG. 1A is referred to as a first plane, and is shown in FIG. 1B. 56 windows (# 1 to # 56) from the position where the inspection image data is shifted by 1/2 window on the X-axis.
The inspection image data divided in step 2 is called the second plane, as shown in FIG.
As shown in (c), the inspection image data is shifted from the Y-axis by 1/2 window to 56 windows (# 1 to # 1).
The inspection image data divided in # 56) is called a third plane, and the plane of the inspection pixel data is displaced by a 1/2 window on the X axis and a 1/2 window on the Y axis as shown in FIG. 1D. From to 49 windows (# 1 to # 4
The inspection image data divided in 9) will be called the fourth plane.

FIG. 2 is a schematic configuration diagram showing the configuration of an embodiment of the defect inspection apparatus according to the present invention.

The defect inspection apparatus of this embodiment includes a line sensor 1 for picking up an image of an object to be inspected, a signal processing / transmission unit 2, an image processing unit 3, a rotary encoder 4 for outputting a signal for detecting the rotation speed of a roller 7, and It is composed of a light guard 5 which keeps a printed matter as an object to be inspected at a predetermined brightness.

The signal processing / transmitting unit 2 has an A / D converter (not shown) in which the image pickup signal from the line sensor 1 is incorporated.
With this, for example, it is converted into image data composed of 8-bit gradation data, and this image data is output to the image processing unit 3.

The image processing section 3 is provided with an image memory (not shown) for recording the image data received from the signal processing and transmission section 2 and a defect determiner 6. This image memory records inspection image data of the inspection object and non-defective image data of the printed matter that serves as a reference for determining whether the inspection object is a non-defective product.

As shown in FIG. 3, the defect determiner 6 has a first
The plane forming / determining circuit 61 includes a plane, a second plane, a third plane, and a fourth plane,
The windows of the first plane, the second plane, the third plane, and the fourth plane are simultaneously processed in parallel, respectively.

That is, the first plane, the second plane,
The plane forming / determining circuits 61 of the third plane and the fourth plane operate based on the same operation clock h2, and the same inspection target pixel h3 is input.

When the start signal h1 is input, the plane formation / judgment circuit 61 for the first plane receives the pixel to be inspected h3 based on the synchronization of the operation clock h2, and the gradation level of this pixel to be inspected h3 is checked. And a built-in counter (not shown) is added every time there is a difference in gradation level.

Further, the plane forming / determining circuit 61 of the first plane compares the gradation levels of the pixels to be inspected, and before comparing the gradation levels of the pixels of the 1/2 window in the X-axis direction, The second pattern forming / determining circuit 61 outputs a signal h4 as a start signal h1 for inspecting the window of the second plane.

Further, the plane forming / determining circuit 61 of the first plane compares the gradation levels of the pixels to be inspected, and before comparing the gradation levels of the pixels of the 1/2 window in the Y-axis direction, A signal h5 which is a start signal h1 for inspecting the window of the third plane is output to the third pattern forming / determining circuit 61.

Before the plane forming / determining circuit 61 of the third plane inspects the window of the third plane and compares the gradation levels of the pixels of the ½ window in the X-axis direction in the third plane. In addition, the fourth pattern formation / determination circuit 61 outputs a signal h4 as a start signal h1 for inspecting the window of the fourth plane.

These plane forming / determining circuits 61 are
As shown in FIG. 4, it comprises a judgment circuit 611 and a plane formation circuit 612. The judgment circuit 611 has a counter, and when a start signal h1 is input, it is recorded in the image memory at any time by using this start h1 as a trigger. The pixel to be inspected is received from the non-defective product image data and the inspection image data, and the gradation levels of both are compared,
If there is a difference in gradation level, the count value of the counter is added, and if the added count value exceeds a predetermined reference value, the inspection result h6 indicating that the object to be inspected is defective in printing.
Is output. In addition, the plane forming circuit 6
When the position of the pixel to be inspected reaches a position shifted by 1/2 window in the X-axis direction or the Y-axis direction under the synchronization of the operation clock h2 after the start signal h1 is inputted, the scan position 12 becomes 1 / (2). The shift signal h4 or the shift signal h5 for inspecting the window of the second plane, the third plane, or the fourth plane shifted by two windows is output.

Next, the operation of the defect inspection apparatus of this embodiment will be described with reference to the drawings.

First, a printed matter which is a preselected inspection standard is placed in front of the line sensor 1 and illuminated by the light guard 5 to a predetermined brightness.

After that, the line sensor 1 picks up an image of the printed matter and outputs the picked-up image signal to the signal processing transmission section 2.

The signal processing transmission unit 2 A / D-converts the image pickup signal from the line sensor 1 and outputs non-defective image data consisting of 8-bit gradation level data to the image processing unit 3.

The image processing section 3 records the non-defective image data from the signal processing transmission section 2 in the built-in image memory.

Next, the same processing as described above is carried out to record the inspection image data of the inspection object in the image memory, and then the non-defective image data and the inspection image data are compared with each other to detect the print defect of the inspection object. Start the process of inspecting.

After the inspection image data is recorded in the image memory, the start signal h1 for starting the comparison processing of the two image data is the plane formation / deformation of the first plane of the defect determiner 6.
When input to the determination circuit 61, as shown in FIG.
8-bit scan start pixel (1, 1) of non-defective image data and inspection image data (window # in FIG. 1A)
The grayscale data at the position of the black circle 1) is output to the plane formation / determination circuit 61 of the first plane of the defect determiner 6.

Plane formation / determination circuit 6 for the first plane
The determination circuit 611 of No. 1 compares the received gradation image data of the non-defective image data and the inspection image data of the scan start pixel, and when the gradation levels are different, the built-in counter is added, and then the addition is performed. It is determined whether the count value is greater than or equal to the reference value.

If it is equal to or larger than the reference value, the judgment circuit 611 of the plane forming / judgment circuit 61 of the first plane outputs the inspection result h6 indicating that the object to be inspected is defective in printing, and the object to be inspected. While the inspection of the object is stopped, if the count value is less than the reference value, the same process is performed on the next pixel to be inspected (1, 2). In this way, when the counter addition or the print defect determination process (hereinafter simply referred to as the addition / defect determination process) for the pixels up to (128, 1) in the window # 1 is completed, the count value of the counter is stored in the memory (see FIG. Record (not shown) and clear the count value of the counter to zero.

Similarly, the plane formation / judgment circuit 61 for the first plane performs an addition / defective judgment process for the pixels to be inspected in the windows # 2 to # 8 when the Y-axis direction is 1.

Next, when the operation clock h2 is input, the plane formation / judgment circuit 61 for the first plane sets the count value of the window # 1 recorded in the memory in the counter and inspects the window # 1. Target pixel (2,1)
The addition / defective determination process of is performed in the same manner as described above. Less than,
Similarly, window # 1 when the Y-axis direction is 2
~ Perform processing of window # 8. In this way, the first
The plane formation / judgment circuit 61 of the planes performs addition / addition of windows # 1 to # 8 up to 128 in the Y-axis direction.
Defective judgment processing is performed, and window # 1 to window #
The addition / defect determination process of 8 is completed.

Similarly, the plane forming / determining circuit 61 of the first plane inspects the print defects of the windows up to the pixel (1024, 1024) of the maximum window # 64.

The defect inspecting apparatus of this embodiment, as a result of inspecting in this way, results in all the windows (# 1 to # 6).
When the number of pixels having a difference in gradation level in 4) is less than the reference value, it is determined that the object to be inspected is a good product.

The plane formation / judgment circuit 61 for the first plane forms a window shifted by 1/2 window in the X-axis direction after performing addition / defective judgment processing on the pixel (64, 1). The signal h4 is output to the window / decision circuit 61 of the second plane, and the pixel (10
24, 64), after performing the addition / defective determination process,
A signal h5 for forming a window shifted by 1/2 window in the Y-axis direction is output to the plane forming / determining circuit 61 of the third plane.

Here, in order to briefly explain the operation of the print defect apparatus, the contents of the print defect inspection process for the windows of the second plane, the third plane, and the fourth plane, which are not described, will be briefly described. .

(1) Regarding the window of the second plane After the plane formation / judgment circuit 61 of the first plane performs the addition / defective judgment processing on the pixel (1024, 64), the plane formation / judgment circuit of the second plane When the operation start signal h4 of 61 is output to the plane formation / determination circuit 61 of the second plane, the pixel (1, 65) to be inspected next
Is the first pixel to be inspected in the window # 1 of the second plane. After that, in the same manner as the above-described inspection process in the window of the first plane, the inspection of the print defect in the windows (# 1 to # 56) of the second plane is performed. By the way, the last pixel to be inspected in this second plane is (10
24, 960).

(2) Regarding the window of the third plane After the plane formation / determination circuit 61 of the first plane has performed the above-mentioned addition / defective determination processing of the pixel (64, 1),
The operation start signal h5 of the plane forming / determining circuit 61 for the third plane is set to the plane forming / determining circuit 61 for the third plane.
Then, the pixel (65,1) to be inspected next is
It becomes the first pixel to be inspected in the window # 1 of the plane. Thereafter, the print defects of the windows (# 1 to # 56) of the third plane are inspected as described above. Incidentally, the last inspection target pixel of the third plane is (960, 1024).

(3) Regarding the window of the fourth plane After the plane formation / judgment circuit 61 of the third plane performs the above-mentioned addition / defective judgment processing of the pixel (64, 64), the plane formation / judgment of the third plane / When the operation start signal h4 of the determination circuit 61 is output to the plane formation / determination circuit 61 of the fourth plane, the pixel (65, 65) to be inspected next
Is the first pixel to be inspected in the window # 1 of the fourth plane. Thereafter, the print defects of the windows (# 1 to # 49) of the fourth plane are inspected as described above. Incidentally, the final inspection target pixel of the fourth plane is (960, 960).

According to the above-described embodiment, as shown in FIG. 5, the print defect B which has not been determined to be the print defect in the window 1 and the window 2 is shifted by 1/2 window in the horizontal direction and comes to the center. Is determined to be a printing defect. Also, window 1, window 2, window 3
Further, the print defect C which has not been determined to be a print defect in the window 4 is shifted by ½ window 6 in the vertical direction and comes to the center, so that it is determined to be a print defect.

As described above, since the printing defect is determined in units of the window which is displaced by the predetermined amount in the predetermined direction, the printing defect can be quickly inspected and the printing defect is not missed.

In the defect inspection apparatus of this embodiment, the plane forming / determining circuits 61 of the first plane, the second plane, the third plane, and the fourth plane need only be arranged in parallel, and the FPGA (Field Programmable) Gatearray)
And ASIC (Application Specific Integrated Circui
t) can be easily realized.

The defect inspection apparatus of the above-described embodiment is
Although it is an apparatus for inspecting print defects in window units of four planes that are displaced by ½ window from each other in the X-axis direction and the Y-axis direction, it is possible to measure in the X-axis direction or the Y-axis direction in terms of inspection accuracy and cost efficiency. Of course, it is possible to use only one of them as a defect inspection device.

As another defect inspection apparatus, the window is ½ ^N (N = 0, 1, 2, 3, 4, ...).
It is also possible to shift them, and in this case, the plane forming / determining circuits 61 constituting the defect determiner 6 described above may be increased in parallel by the number corresponding to that.

The defect inspection apparatus according to the above-described embodiment raster-scans non-defective product image data and inspection image data,
Although it is an apparatus for inspecting print defects on a window-by-window basis, it is also possible to use a defect inspection apparatus for inspecting all pixels in the window after inspecting all pixels in the window.

As an inspection method, counters are prepared for the number of windows in the X-axis direction, the counters are switched at every window break, and the preset value is compared with the preset value at the end of one window, If the count value is larger, it is possible to use a defect inspection apparatus that determines that there is a print defect.

[0057]

According to the above-described invention, the plane setting means sets a plurality of planes having mutually shifted windows with respect to the same inspection image data, so that a print defect exists across the boundaries in the windows. Even if there is, there is an effect that it is possible to quickly inspect the printing defect and the printing defect is not missed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the contents that are a prerequisite for an embodiment of a defect inspection apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram showing a configuration of an embodiment of a defect inspection apparatus according to the present invention.

FIG. 3 is a block diagram showing a configuration of a defect determiner in FIG.

FIG. 4 is a block diagram showing a configuration of a plane forming / determining circuit in FIG.

FIG. 5 is a diagram illustrating a print defect inspection process.

FIG. 6 is a diagram illustrating a window.

FIG. 7 is a block diagram illustrating a processing operation of a conventional defect inspection apparatus.

FIG. 8 is a diagram illustrating a conventional print defect inspection process.

[Explanation of symbols]

 1 line sensor 2 signal processing transmission unit 3 image processing unit 4 rotary encoder 5 light guard 6 defect determiner 7 roller

Claims (5)

[Claims] 1. A defect inspection apparatus that divides inspection image data of an object to be inspected into a plurality of windows into one plane and determines the presence / absence of a defect for each window constituting the plane, and the same inspection image data is used. A plane setting means for setting a plurality of planes having windows shifted from each other, and the same inspection image data is judged based on the plurality of planes. 2. The defect inspection apparatus according to claim 1, wherein the plurality of planes set by the plane setting means are simultaneously and in parallel determined for defects. 3. The window is composed of a plurality of pixels arranged on a grid in the X and Y axis directions, and the plane setting means shifts the inspection object window in the X and Y axis directions by a predetermined number of pixels from each other. The defect inspection apparatus according to claim 1, wherein a plurality of planes having shifted windows are set. 4. The plane setting means has raster scan collecting means for sequentially collecting inspection image data of an object to be inspected along the X-axis direction, and based on the position of the inspection image data collected first. The inspection image data is divided into a plurality of windows and a first plane setting unit that sets a reference plane, and the plane set by the first plane setting unit is being scanned, the inspection image data is first scanned. When a position shifted by a predetermined number of pixels in the X-axis direction from the position of the inspection image data collected in (1), the inspection image data is divided into a plurality of windows with the position as a reference and set by the first plane setting means. Second plane setting means for setting a plane such that each window is located at a position displaced by a predetermined number of pixels in the X-axis direction from the window position; When the plane set by the plane setting means is being scanned, when the scan position of the inspection image data reaches a position displaced by a predetermined pixel in the Y-axis direction from the position of the inspection image data initially collected, the position is used as a reference. A third plane in which the inspection image data is divided into a plurality of windows and planes are set so that each window is located at a position displaced by a predetermined number of pixels in the Y-axis direction from the window position set by the first plane setting means. While scanning the setting unit and the plane set by the third plane setting unit, when the scan position of the inspection image data is displaced from the first reference position by a predetermined pixel in the X-axis direction,
The inspection image data is divided into a plurality of windows on the basis of the position, and planes are set so that each window is located at a position shifted by a predetermined pixel in the X-axis direction from the window position set by the third plane setting means. 4. The defect inspection apparatus according to claim 3, further comprising: a fourth plane setting unit that performs: 5. The defect inspection apparatus according to claim 3, wherein the pixel shift amount is half the number of window constituent pixels in both the X and Y axis directions.