JPS628045A - Apparatus for detecting flaw - Google Patents

Abstract

PURPOSE:To accurately detect the shape or singularity of the flaw possessed by an article to be detected, by mounting a moving means, a first unidimensional image detection means and a second unidimensional image detection means. CONSTITUTION:An article 1 to be detected is moved by a belt conveyor 2 and scanned by a first unidimensional image detection means 3. The flaw 10 of the article 1 to be detected is converted to an image signal 31 which is, in turn, inputted to a flaw detection circuit 5. The circuit 5 sends the flaw detection signal on the article 1 to be detected to a counter circuit 72 which, in turn, starts the counting of the output signal of a moving amount detection means 6. Thereafter, the circuit 72 outputs the counter output signal to a memory circuit 82 when the count value reached the value corresponding to the amount moving between the detection means 3 and a second unidimensional image detection means 4. The circuit 82 stores the image signal 41 of the detection means 4 as two-dimensional image information through an A/D converter circuit 81 and said two-dimensional image information is displayed on a display device 83. By this method,the shape or singularity of the flaw possessed by the article to be detected can be accurately detected.

Description

[Detailed description of the invention] 11117) iwa1 momme! The present invention relates to a defect detection device, and particularly to a defect detection device that detects defects such as scratches, deformation, coloring, etc., and shape specificities (hereinafter referred to as defects, etc.) of an object to be detected while moving the object. The present invention relates to a detection device.

Conventional Technology and Problems Industrial television equipment (hereinafter referred to as ITV) and X-ray television have traditionally been used as defect detection devices that inspect defects and specificities on the surface and inside of an object while moving it at a constant speed. equipment is used. According to such conventional technology, an object to be detected is decomposed into pixels by an image pickup tube, CCD, etc. (hereinafter referred to as an image pickup tube), sequentially converted into electrical signals by electron beam or charge scanning, and then reproduced as an image by a CRT or the like to display the above-mentioned images. Defects etc. are detected.

As a similar conventional technique, there is a method in which the object to be detected is moved at a constant speed and imaged with one-dimensional COD, and the image is reproduced using a computer or recording device. The defect is detected by replacing the object by moving the object and reproducing the stored image signal on a CRT.

According to such conventional technology, a defect, etc. of an object to be detected is resolved into fixed pixels (i.e., sampled) regardless of its shape or form, and is scanned or moved at a fixed scanning speed or moving speed. The defect is detected and the image is reproduced to identify whether it is a defect or not.

Therefore, for example, if the defect L is in the form of a narrow line or needle, the pixel size will be too large and the defect will be clogged.

Depending on the balance between the scanning speed and the moving speed as well as the resolution), the defect cannot be detected accurately and the reliability of the defect detection device cannot be satisfied.

These problems in the conventional technology can be solved to some extent by using a high-resolution ITV with a significantly increased number of pixels, by making the moving speed of the object to be detected extremely slow, and by using a large-capacity storage device, etc. However, the scanning time and travel time become long, which not only goes against the original purpose of efficiently detecting defects in the object to be detected, but also makes the equipment larger, more complicated, and more expensive.
It lacked practicality. In addition, in the imaging method using two-dimensional scanning, even if a large number of pixels are arranged in a high-density and high-resolution manner, most of the pixels are not used effectively on average; The rate was also poor.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional unresolved problems, and is capable of detecting defects, etc. of an object to be detected with high precision and efficiency, regardless of its shape or form, using a simple configuration. The object of the present invention is to provide a defect detection device that is capable of detecting defects.

i''LdanJLJ In order to achieve the above object, the defect detection device according to the present invention comprises: a moving means for variably adjusting the moving speed of an object to be detected; A first one-dimensional image detection means for scanning to detect the presence or absence of a defect in the object to be detected, and a second one-dimensional image detection means for detecting in detail the shape and specificity of the defect in the object to be detected. In response to a detection signal obtained by the first one-dimensional image detection means detecting a defect in the object, the moving means gradually adjusts the moving speed of the object to be detected, The second one-dimensional image detection means accurately detects the shape and specificity of the defect of the object to be detected.

N- Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same members that have the same functions are designated by the same reference numerals, and their explanations will be omitted.

FIG. 1 is a schematic diagram showing an embodiment of the present invention. l
2 is a moving means such as a belt conveyor on which the detected object 1i is placed and moved; 3 is a first one-dimensional image detecting means; 4 is a first one-dimensional image detecting means; 2
This is a one-dimensional image detection means.

The first one-dimensional image detection means 3 detects the presence or absence of a defect in the object 1 to be detected, and inputs its output signal to the defect detection circuit 5. The defect detection circuit 5 is constituted by a normal image signal processing circuit that extracts an image signal from the output signal of the image detection means 3, performs waveform shaping such as differentiation and integration as appropriate, and compares it with a reference signal level. I can do that.

Reference numeral 6 denotes movement amount detection means for detecting the movement amount of the object to be detected, and when the movement means 2 is a belt conveyor, it may be a pulse generator or the like that is linked to the belt conveyor. Reference numeral 61 indicates an output signal of the movement amount detection means 6. Reference numeral 7 denotes a control section which includes a control circuit 71 for controlling the drive device 21 of the movement means 2 and a counter circuit 72.

The second one-dimensional image detection means 4 detects the shape and details of the defect on the object 1 to be detected, and inputs an output signal to the display section 8.

The display section 8 includes an A/D conversion circuit 81 that digitally converts the analog signal output from the image detection means 4, a storage circuit 82 that stores the converted digital signal, and a display device 83 such as a CRT. ing. In this embodiment, the storage circuit 82 is connected to input the output signal of the counter circuit 72 of the control section 7 and to store the digital signal output from the A/D conversion circuit 81 as a trigger signal for storage operation. There is. The read signal from the memory circuit 82 is input to the defect evaluation section 9. The defect evaluation section 9 includes a measurement circuit 91 that measures the size of the defect based on the read signal, a determination circuit 92 that compares the measurement result with a reference value and determines whether the defect is good or bad, and generates an alarm based on the determination result. The judgment result signal is further connected to the control circuit 71 of the control section 7.

According to this embodiment, the object l to be detected is moved by a belt conveyor 2 whose moving speed is changed and is scanned by the first one-dimensional image detection means 3, and the defect lO of the object to be detected 1 is converted into an image signal 31. and is input to the defect detection circuit 5 as an electrical signal.

When the defect detection circuit 5 recognizes a defect on the object l as a defect, it sends a defect detection signal, which is an output signal, to the counter circuit 72. The counter circuit 72 starts counting the output signal (for example, the output pulse of the pulse generator) of the movement amount detection means 6 from the moment it receives the defect detection signal 1. Thereafter, the counter circuit 72 calculates the counted value of the detected object l at the first one-dimensional image detecting stage 3 and the second one-dimensional image detecting means 4.
A counter output signal is output to the memory circuit 82 at the moment (or just before) the value corresponding to the amount of movement between the two is reached. The storage circuit 82 receives the counter output signal, which is a trigger signal for storage operation, and transfers the image signal 41 from the second one-dimensional image detection means 4 to the storage circuit 82 via the A/D conversion circuit 81 as two-dimensional image information. be memorized as . In the above, the counter output signal output from the two-force counter circuit 72 is also input to the control circuit 71 to control the drive device 21 so that the first stage of movement 2 can be operated at a low speed, for example. The two-dimensional image information stored in the memory circuit 82 is CR
The condition of the defect can be shown to the operator by displaying it on a display device 83 such as T, and furthermore, the size of the defect can be measured via the defect evaluation section 9, and if the defect cannot be overlooked, an alarm, notification, and transportation means can be displayed. or the object to be detected can be removed by shaking it off). Further, the output signal of the determination circuit 92 allows the control circuit 71 to return to the desired state upon completion of the determination work, and allows the moving means 2 such as a belt conveyor to operate at high speed again.

In the above description, the control unit 7 automatically detects defects from the image signal 31 detected by the one-dimensional image sensor 3 (for example, by comparing the image signal level with a preset threshold value) and detects the detected object l. It has been explained that when the defect reaches the detection range of the second one-dimensional image detecting means 4, the moving speed is automatically adjusted or the second one-dimensional image detecting means 4 minutely detects the defect. It is also possible for the operator to manually adjust the control section 7 from the outside to freely adjust the moving speed of the moving means 2 as appropriate, or for the second one-dimensional image detection f-stage 4 to take an image. Hereinafter, the present invention will be explained in detail with reference to FIGS. 2 to 4.

FIG. 2 is a flowchart explaining the operation of one embodiment of the present invention. In response to a start command (Zoo in the figure), the moving means moves the object to be detected at a normal speed (J:, which corresponds to high speed movement and has a resolution that allows the first one-dimensional image detecting means to detect the presence or absence of defects. The output signal of the first one-dimensional image detection stage f is checked for the presence or absence of defects by a defect detection circuit (reference numeral 5 in FIG. 1) (reference numeral 102).゜103),
If a defect is recognized, the counter circuit is commanded to start counting (104). In the illustrated embodiment, the object to be detected moves at a low speed after the counter starts, which is different from the description of the previous embodiment. (105)
, Low-speed movement refers to the speed at which the second one-dimensional image detection detection means can obtain a resolution that allows detailed detection of the shape and specificity of the defect.Then, the count value of the counter circuit is set to a preset value. (106), and when the counted value reaches the set value (i.e., the detected object has reached the second one)
(when reaching the imaging range of the dimensional image detection means), the second
The image output signal of the one-dimensional image detection means is sent to the storage circuit (
The data is stored as two-dimensional information (107) in FIG. 1, reference numeral 82). Note that in the above embodiment, the object to be detected moves at low speed (
105) with the L notation count value and the set value (105)
It is also possible to perform this after step 6). The information stored in the memory circuit is displayed on a display device (108), or a defect is measured (109) by a defect evaluation section (109 in FIG. 1), and the measured value is compared with a limit value (110). , Jll constant value has not reached the limit, the moving speed of the object to be detected returns to normal high-speed movement. Also,
If the measured value exceeds the limit, an alarm signal is generated to inform the operator of a defect in the detected object. Alternatively, the object to be detected can be removed via a manipulator, and furthermore, the object to be detected can be subjected to various types of removal processing such as coloring the object to be detected.

In the drawings of FIGS. 3 and 4, reference numeral 200 indicates the scanning direction of the one-dimensional image sensor 3.4.

201 indicates the moving direction of the belt conveyor 2. Further, reference numeral 202 is a position display line indicating the same virtual position for explaining the present invention in detail.

FIG. 3(A) shows a schematic diagram of the surface of the detected object 1 viewed from the one-dimensional image detection/L stage 3 side (that is, from the top of the detected object). A defect 203 is a defect with a large aspect ratio (for example, a groove-like crack) extending in the scanning direction 200 and the moving direction 201. According to the conventional defect detection method, the object to be detected is moved at a constant speed by a moving means, and seven imaging stages such as a television camera perform horizontal scanning in the scanning direction 200 while sequentially scanning in the vertical direction (corresponding to the moving direction 201). The electron beam is scanned to image defects on the object to be detected. Therefore, if the defect is linear with a large aspect ratio as described above, the object to be detected 1 may be moved by the moving means during vertical scanning of the electron beam, or may be buried within the scanning sampling interval. In some cases, accurate defect detection could not be performed. However, according to the present invention, the defect 2 on the detected object l
03, the presence or absence of a defect is detected by the first one-dimensional image detection means, and the moving speed of the belt conveyor 2 is changed to a low speed in accordance with the detection signal. Since the relative moving speed of the defect 203 with respect to the second one-dimensional image detecting means 4 becomes slow, the defect 203 is precisely scanned by the second one-dimensional image detecting means 4 with sufficient resolution during movement, and as a result, A reproduced image expanded in the moving direction 201 as shown in FIG. 3(B) can be stored or displayed. That is, the linear defect 20
3 is an image detected as a defect detection image enlarged with sufficient resolution in the moving direction.

FIG. 4(A) is a schematic diagram of the end of the detected object 1 viewed from the one-dimensional image detecting means 3 side. This is a diagram illustrating the operation of the present invention when detecting with high resolution a shallow chip, crack, etc. 204 occurring at the end of the detected object l. In this example, the first one-dimensional image detection means 3 detects the detected object. By detecting the detection signal and slowing down the moving speed of the detected object l in the moving direction 201 based on the detection signal, the image that is normally detected and reproduced as shown in FIG. figure(
As shown in B), it is enlarged, stored and reproduced, and even the slightest chip or crack 204 can be reliably detected.

In the above embodiment, the defect length measuring circuit 91 directly inputs the image signal 41 from, for example, the second one-dimensional image detecting means 4, and compares the signal level with a preset threshold to detect defects, etc. It can also be configured with a comparison circuit, an A/D conversion circuit, etc., which converts it into a digital pulse signal according to the data.

Also the control unit 7 and display! A portion of the 1I18, or the defect evaluation section 9, can also be constituted by a microcomputer or the like that inputs digital signals and performs predetermined logical operations and time operations.

To explain the above-mentioned embodiment more specifically with an example, 1
The dimensional image detection means 4 scans 500-bit one-dimensional pixels at a speed of 20,000 times per second, and scans the detected object 1.
is 10 c/s at low speed by belt conveyor 2.
■It moves at a speed. The field of view of the one-dimensional image sensor 4 in the scanning direction is adjusted to 100 square meters by a lens. On the other hand, the storage capacity of the image memory is 5
00 bits (pixels) and 500 bits (pixels) corresponding to the scanning direction. Therefore, the image signal 41 output from the second one-dimensional image detection f stage 4 is sequentially transmitted via the A/D converter 81. 1 bit (pixel) in the 0 image storage circuit 82 recorded in the image storage circuit 82 is 5μ layer at the distance of the object to be detected from the moving speed, scanning speed and storage capacity of the moving means 2. corresponds to Note that in the scanning direction, this corresponds to 200 final layers per bit (pixel) due to the width of the field of view and the storage capacity. That is, an area of 2.5 mm in the moving direction and Loom in the scanning direction on the object 1 to be detected is 500 mm on the image storage circuit.
The image signal temporarily recorded in the zero image storage circuit 82, which corresponds to the detected bit and has been enlarged, is read out and input to the defect length measuring circuit 91, and the size of the defect, etc. of the object to be detected is measured. is measured corresponding to the moving direction and/or scanning direction based on the enlarged and recorded image signal,
The measurement signal is input to the determination circuit 92 to warn of a defect, and also adjusts +If and the moving speed of the belt conveyor 2 via the control unit 7 etc., thereby achieving the effect of detecting defects at high speed and with high efficiency. be.

In the description of L, the one-dimensional image detection means is, for example, C
Of course, it is possible to use a solid-state imaging device such as an OD, an optical image sensor, an x&1 image intensifier by irradiating X-rays, or an ultrasonic line scanner.

Effects of the Invention According to the present invention, the presence or absence of a defect in the detected object is detected by the first one-dimensional image detection means while the detected object is moved by the moving means.

Based on the detection signal, the moving means moves the object to be detected at low speed. The second one-dimensional image detection means detects defects and the like of the object to be detected with precision and high resolution, and stores, reproduces, or determines an enlarged defect image based on the detected image information.

That is, since the moving speed of the moving means is optimally set and controlled, it is possible to reliably detect defects that would have been overlooked in the prior art. Furthermore, the moving speed of the moving means is adjusted to high speed in areas where there are no defects, etc., and to low speed in areas with subtle defects, etc., so inspection for defects, etc. of the object to be detected can be performed efficiently in a short time, resulting in high workability. It also has

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention, and FIGS. 2 to 4 are explanatory diagrams explaining the present invention in detail. l...Object to be detected 2...Movement means 3...First one-dimensional image detection means 4...Second one-dimensional image detection f-stage 5...Defect detection circuit 6...Movement Quantity detection means 7...control section 8...display section 9...defect evaluation section Fig. 3 (A) (B) Fig. 4 (A) (B)

Claims (1)

[Claims] (1) A moving means that variably adjusts the moving speed of the object to be detected, and a first means that scans in a direction transverse to the moving direction of the object to detect the presence or absence of a defect in the object. a dimensional image detecting means, and a second one-dimensional image detecting means for detecting in detail the shape and specificity of the defect of the object to be detected; Based on the detection signal, the moving means adjusts the moving speed of the object to be detected slowly and rapidly, and the second one-dimensional image detecting means detects the shape and specificity of the defect of the object to be detected. Characteristic defect detection device.