JPH073394B2 - Foreign material measuring device for transparent members - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign matter measuring device for detecting and measuring foreign matter mixed in a transparent member.

[0002]

2. Description of the Related Art Generally, a transparent member such as a transparent acrylic resin which is used after being formed into a plate shape is mounted on a tube surface in order to protect a CRT surface as a display device. In this case, the image displayed on the CRT is viewed through this transparent acrylic resin plate. Therefore, if foreign matter such as dust is mixed in with this, the light of the image on the CRT surface hits the foreign matter and is scattered. Therefore, the image cannot be viewed accurately. Further, since acrylic resin has a high insulating property, it is also used as an electric insulating material, but if foreign matter such as dust is mixed in, the insulating property will deteriorate. For this reason, the raw material is managed by measuring the foreign substances mixed in the raw material at the stage of powder raw material before manufacturing into an acrylic resin plate, but normally, such foreign substances such as dust can be easily confirmed with the naked eye. It is so small that it is difficult.

Therefore, in order to detect and count the foreign matter such as dust, the amount of foreign matter mixed in a certain volume is measured. Therefore, conventionally, a small piece of a transparent acrylic resin plate having a thickness of about 3 mm and a length and width of about 5 mm is manufactured as a sample from a powder raw material, and the small piece is observed with a microscope to count the number of foreign matters mixed in. However, even though the thickness is about 3 mm, the depth of focus becomes narrower when enlarged with a microscope, and only a very small portion in the thickness direction (Z-axis direction) can be observed. Therefore, the sample is fixed, and the sample is moved upward or downward in the Z-axis direction with a microscope while being focused and moved at a constant interval of, for example, 3 μm to observe the foreign matter, and whether the total number is within the allowable value. It was judged whether it was good or bad.

[0004]

However, in such a method, when the thickness of the sample is 3 mm and the focus of the microscope is 10 μm in the Z-axis direction, the microscope is moved in the Z-axis direction. If you don't shift it 300 times, you can't observe the whole thing, and moreover, you can move it in the X-Y direction determined by the field of view of the microscope and count it.
It takes a lot of time and money, and since the number of foreign substances was counted by humans, there were problems such as errors.
Therefore, if you try to count the foreign particles by the normal image processing using the image processing device, it is 10 μm observed by the microscope.
Since the image information of each screen is written on the hard disk and the image processing is performed on each, the capacity of one screen hard disk is used when the sample has a thickness of, for example, about 2 mm. Is about 256 KB, and a large-capacity hard disk of 256 × number of screens KB is required for all the inspection target screens, and there is a problem that the measurement time is long.

[0005]

The present invention relates to an optical microscope for magnifying and observing a sample equipped with a drive mechanism for moving in the Z-axis direction, and an image taken by being connected to an eyepiece section of the optical microscope. Image pickup device, an A / D converter for digitally converting an image signal from the image pickup device, and the A / D converter
The frame memory that stores the digital image information from the D converter and the image information stored in this frame memory and the newly input image information are compared and calculated, and the foreign matter mixed in the sample has high brightness. An image processing unit that has an arithmetic unit for accumulating by either accumulation or low-intensity accumulation, measures the foreign matter by image-processing the image information in the frame memory, and an analog image signal stored in the frame memory. A D / A converter for conversion, a function for controlling a drive mechanism in the Z-axis direction, a function for selecting high brightness accumulation and a low brightness accumulation, and a frame.
A computer having a function of instructing writing and rewriting to a frame memory, sequentially comparing and calculating image information and accumulating high brightness or low brightness to accumulate foreign matter on the frame memory, and this foreign matter. Is measured.

[0006]

[Operation] The optical microscope, under the control of the computer,
The Z-axis driving device automatically moves the Z-axis direction upwards along the Z-axis cross section at a constant pitch to bring the image into focus at a constant pitch of 2 to 3 μm. , A portion where a foreign substance (dark foreign substance) exists is converted into an electric signal as a dark signal and the other background is converted to an electric signal, respectively, and then converted into a digital signal by an A / D converter. ALU
Input to (Calculator). In this ALU, the image information currently input and the image information previously stored in the frame memory (bright signal only for the background which is initially set at the present time)
Is fed back for comparison calculation. By this comparison operation of the image information, the dark signal indicating the foreign matter is stored in the frame memory instead of the previously stored background image information. The foreign matter stored in the frame memory is measured and D /
It is converted into an analog signal by the A converter and displayed on the display device. The writing and rewriting of information in the frame memory are performed according to the commands of the computer.

[0007]

Embodiment 1 of the present invention will be described with reference to FIGS.
This will be described in detail with reference to FIG. FIG. 1 is a block diagram of the present invention,
2 to 6 show each screen 1 in the Z-axis direction displayed on the display device.
It is 6. FIG. 7 is a circuit diagram for selecting high brightness storage or low brightness storage, and FIG. 8 is a flow chart. In FIG. 1, reference numeral 1 is an optical microscope, which is equipped with a Z-axis drive mechanism 2 which can be vertically driven by a pulse motor or the like at a constant pitch (for example, 2 to 3 μm) in the Z-axis.
The drive mechanism 2 in the axial direction is drive-controlled by a computer 11, and an X-axis is provided on the side of the objective lens section 1a.
The sample 13 placed on the Y-table 3 is positioned, and the image pickup device 5 is connected to the eyepiece 1b side. Reference numeral 3 is an XY table on which the sample 13 is placed.
X-Y axis direction drive mechanism 4 for moving in the -Y direction
It is equipped with. An image pickup device 5 is connected to the eyepiece 1b of the microscope 1. An image processing unit 6 is connected to the output side of the image pickup device 5 via an A / D converter 7.

In the image processing unit 6, the ALU 9 and the D / A converter 10 for sequentially comparing and calculating the previous image information stored in the frame memory 8 and the image information currently input, and commands to each unit. , And a controlling computer 11 are built-in. The ALU 9 compares and operates the image information written in the frame memory 8 with the current image information, and based on the instruction from the computer 11, the instruction decoder 1
Either high brightness accumulation or low brightness accumulation is selected by 7, and the foreign matter 14 in each image information is sequentially accumulated. The computer 11 has a function of controlling the drive mechanism 2 in the Z-axis direction and a drive mechanism 4 in the XY-axis direction, a function of adding image information and selecting high luminance accumulation or low luminance accumulation, and the like. There is. The frame memory 8 has a memory capacity of, for example, a sampling frequency of 12 MHz and a quantization of 8 bits for recording image information of one frame. Reference numeral 12 is a display device, 13 is a sample, 14 is a foreign substance mixed in the sample 13, 15 is a bubble, and 16 is a display screen in the Z-axis direction which is imaged or displayed on the display device 12.

Next, the action and operation will be described in detail with reference to FIG. Acrylic resin is used as sample 13,
A case of measuring the foreign matter 14 such as dust mixed in the sample 13 will be described. First, as a preparatory step, a small amount of a powdery acrylic resin raw material is taken out, and a small piece of a rectangular transparent acrylic resin having a thickness of about 3 mm and a length of about 5 mm is molded as a sample 13. This sample 13 is X-
It is placed on the Y-table 3 and positioned so that the cross-section can be observed in the Z-axis direction by the objective lens section 1a of the optical microscope 1, and the focus is on the deepest part (bottom surface) of the sample 13. .

First, a case will be described in which low-intensity storage for accumulating the foreign matter 14 as a dark signal is performed by a command from the computer 11. Under the control of the computer 11, the optical microscope 1 is automatically moved upward along the cross section in the Z-axis direction at a constant pitch by the Z-axis direction driving device 2, The image is taken by the image pickup device 5 while being focused at a constant pitch of 3 μm,
Focused image, that is, constant pitch a, b, c ...
-Each image (display screen 16) is obtained. This image information is digitally converted by the A / D converter 7, and then variously processed by the image processing unit 6, and these are displayed on the display device 12.

Here, according to a command from the computer 11,
Since the instruction decoder 17 selects the low-intensity storage for displaying the foreign matter 14 as a dark signal, for example, the pitch interval of the sample 13 is 3 μm, and the display screens 16 at the pitches a, b, and c are respectively shown in FIG. 2 to 4, at the pitch a, the coordinates (1,1), (1,3), (3,2), (3,4) in the display screen 16 shown in FIG. Foreign matter 14 is mixed in the displayed portion. Similarly, at pitch b, as shown in FIG. 3, coordinates (0,
Foreign matter 14 is detected in 0), (2, 2), (3, 3),
At the pitch c, the foreign matter 14 is detected at the coordinates (1, 4) as shown in FIG. As described above, in the display screen 16 imaged by the imaging device 5, a portion where the foreign matter 14 exists is converted into an electric signal as a dark signal and the other background is converted into an electric signal, and the image signal is A / D converted. Bowl 7
It is converted into a digital signal by and input to the image processing unit 6.

In the image processing unit 6, as an initial condition, a frame memory 8 is issued in response to a command from the computer 11.
Stores image information indicating a bright signal of only the background. Therefore, first, as shown in FIG. 2, the display screen 16 displayed in bright and dark is converted into a bright and dark electric signal by the image pickup device 5, and converted into digital image information by the A / D converter 7. This digital image information is input to the ALU 9. In the ALU 9, as shown in FIG. 7, the image information currently input (input A) and the image information previously stored in the frame memory 8 (bright signal only for the background which is initially set at the present time) (input B) is fed back, and the comparator 23
It is compared whether <B or A> B, and the result is that the output from either AND24 or AND25 is sent to the frame memory 8 via OR26 or OR22.
Memorized in. That is, as a result of the comparison, since the dark signal is selected, the dark signal indicating the foreign matter 14 is stored in the frame memory 8 in place of the previously stored background image information at the location where the foreign matter 14 exists. It The writing and rewriting of the image information in the frame memory 8 are performed by the command of the computer 11.

Next, when the optical microscope 1 is moved upward by 3 μm, the optical microscope 1 comes into focus at the position shown in FIG. 3, and this image is similarly converted into an image signal displayed by a light and dark signal by the image pickup device 5, and similarly. , After being converted into a digital image signal by the A / D converter 7, the dark signal is accumulated by being compared with the image information (the image shown in FIG. 2) previously stored in the frame memory 8 by the ALU 9. As shown in FIG. 5, coordinates (0,
0), (1,1), (1,3), (2,2), (3
2), (3, 3) and (3, 4) are output as dark signals indicating the foreign matter 14 and stored in the frame memory 8.

Further, when the optical microscope 1 is moved upward by 3 μm, the image is focused at the position shown in FIG. 4, and this image is converted into an image signal in the same manner as described above, and the A / D converter 7 causes the digital image signal to be converted. Is converted to the image information stored in the frame memory 8 by the ALU 9, and the dark signal is accumulated, and the coordinates (0, 0), (1,
1), (1,3), (1,4), (2,2), (3
2), (3, 3) and (3, 4) are stored in the frame memory 8 as dark signals indicating the foreign matter 14. In this manner, the foreign matter 14 in the sample 13 is accumulated as a dark signal for each pitch one after another for about 500 × 500 pixels. Actually, it was observed by moving even in the X-Y axis direction,
Measurement of about 0 screen is performed. In this way, the image information in which dark signals are successively stored is stored in the frame memory 8, the image information in the frame memory 8 is rewritten one after another, and the image information in which the foreign matter 14 is measured is D
A / A converter 10 performs analog conversion, and display device 12
Are displayed in sequence.

In this way, the Z-axis direction of the sample 13 is observed by the optical microscope 1, and the result is imaged by the imaging device 5 at about 30 images per second. When the observation of the cross section of the sample 13, that is, the Z-axis direction is completed, the image information from the final screen is stored in the frame memory 8. Therefore, the image information of this final screen is subjected to image processing by means such as ordinary binarization processing, and the accumulated foreign matter 14 is counted. It should be noted that since the foreign matter 14 is rarely located on the same coordinate stochastically, it is not considered in this embodiment.
Further, the initial image of the frame memory 8 initialized by the computer 11 is not limited to the above-mentioned embodiment, but may be the first display screen 16 observed by the optical microscope 1.

Next, when high-intensity storage is performed, a signal having a large comparison result in the comparator 18 is stored as the bright signal of the foreign matter 14, which is opposite to the above-described low-brightness storage. The spots are accumulated, processed in the same manner as above, and the foreign matter 14 in the sample 13 is measured.

[0017]

Second Embodiment of the Invention A second embodiment of the present invention is a foreign matter 1
An example of measuring 4 and bubbles 15 will be described with reference to FIGS. 7 and 8. Black foreign object 1 as a dark signal
4 and white bubble 15 as a bright signal,
First, low-intensity accumulation is performed on the foreign matter 14, and then high-intensity accumulation is performed on the bubbles 15. According to the flow chart shown in FIG. The brightness accumulation is switched to accumulate the foreign matter 14 and the bubbles 15. Therefore, as a circuit for decoding the command of high brightness accumulation or low brightness accumulation and writing the selected signal, for example, in the case of high brightness accumulation,
As shown in, when the signal to be fed back is B, the comparator 1
In 8, the new input A and the fed back input B are compared, and when the input A is large, the comparison output A> B becomes 1 and the input A is the command for high-intensity storage writing from the computer 11. Then, it is written in the frame memory 8. Input B
Is large, the comparator output A <B of the comparator 18 becomes 1, and the output B of the frame memory 8 is written in the frame memory 8 in accordance with the high brightness storage command. In the case of low brightness accumulation, contrary to the above, a signal with a small comparison result of the comparator 23 is written in the frame memory 8.

Therefore, when measuring the bubble 15, first, the high-luminance accumulation is instructed by the computer 11 according to the flow chart shown in FIG. 8, and the bubble is generated in the same manner as in the first embodiment. 15 is stored in the frame memory 8 as a bright signal, and the result is temporarily stored in the image file. Next, the computer 11 issues an instruction for low-luminance storage, and accordingly, the foreign matter 14 is stored in the frame memory 8 as a dark signal, and the result is similarly stored in the image file. In this way, the image information about the foreign matter 14 and the air bubble 15 stored in the image file is read out to the buffer memory (not shown), image-processed to measure the air bubble 15 and the foreign matter 14, and D /
It is A-converted and displayed on the display device 12.

[0019]

According to the present invention, an optical microscope for observing a sample having an automatic focusing mechanism and a driving mechanism for moving in the Z-axis direction, and an image taken by being connected to an eyepiece portion of the optical microscope are taken. Image pickup device, an A / D converter for digitally converting an image signal from the image pickup device, and the A / D converter
The frame memory that stores the digital image information from the D converter and the image information stored in this frame memory and the newly input image information are compared and calculated, and the foreign matter mixed in the sample has high brightness. An image processing unit that has an arithmetic unit for accumulating by either accumulation or low-intensity accumulation, and that processes the image information in the frame memory to measure foreign matter, and the image information stored in the frame memory in analog form. A D / A converter for conversion, a function for controlling a drive mechanism in the Z-axis direction, a function for selecting high brightness accumulation and a low brightness accumulation, and a frame.
Equipped with a computer having a function of instructing writing and rewriting to the frame memory, the image information is sequentially compared and calculated, and the foreign matter is accumulated on the frame memory by either high luminance accumulation or low luminance accumulation. At the same time, since this foreign substance was measured, the foreign substance in the sample
Since all the images are stored in one image, it is sufficient to perform image processing on the final screen and measure the foreign matter, which saves inspection time and shortens the time, and also saves a single photo of the image for storage, which saves money. Become.

[Brief description of drawings]

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

FIG. 2 shows an embodiment of the present invention and shows a screen of pitch a.

FIG. 3 shows an embodiment of the present invention and shows a screen of pitch b.

FIG. 4 shows an embodiment of the present invention and shows a screen of pitch c.

FIG. 5 shows an embodiment of the present invention and shows an accumulation screen of pitch a and pitch b.

FIG. 6 shows an embodiment of the present invention and shows a storage screen from pitch a to pitch c.

FIG. 7 shows an embodiment of the present invention, and is a circuit diagram for selecting low luminance accumulation and high luminance accumulation.

FIG. 8 is a flow chart showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical microscope 2 Driving mechanism in Z-axis direction 5 Imaging device 6 Image processing unit 7 A / D converter 8 Frame memory 9 Computing device 10 D / A converter 11 Computer 12 Display device 13 Sample 14 Foreign matter 15 Bubbles

Claims (1)

[Claims] An optical microscope for magnifying and observing a sample equipped with a drive mechanism for moving in the Z-axis direction, an image pickup device for taking an image by being connected to an eyepiece part of the optical microscope, and an image pickup device from the image pickup device. Digital conversion of image signals A
A / D converter, a frame memory for storing digital image information from the A / D converter, and the image information stored in the frame memory and newly input image information are compared and calculated. And an image processing unit for accumulating foreign matter mixed in the sample by either high-intensity accumulation or low-intensity accumulation, and image-processing the image information in the frame memory to measure the foreign matter. , A D / A converter for analog-converting the image information stored in the frame memory, a function for controlling the drive mechanism in the Z-axis direction, a function for selecting high brightness accumulation and low brightness accumulation, and A computer having a function of instructing writing and rewriting to a frame memory, and by sequentially comparing and calculating the image information, the foreign matter is accumulated with high brightness or low brightness. Serial frame - on the frame memory while storing the Z-axis direction of the foreign matter, the foreign matter measuring apparatus of a transparent member, characterized in that to measure the foreign object.