JPS6373139A - Surface inspecting system - Google Patents

Abstract

PURPOSE:To make it possible to inspect the state of a surface positively at a high speed without complicating the system, by periodically arranging slits having different transmittances, illuminating the surface of a body to be inspected with slit light beams having different intensities, picking the image of the surface in the specified scanning direction, and processing the output signals. CONSTITUTION:Slits having different transmittances are alternately arranged on a multiple-line chart 1a of a lighting part 1. The surface of a body to be inspected 2 is illuminated with light from the lighting part 1. The image of the surface is picked up by a TV camera 3 so that the projected images 1b are in parallel with the horizontal scanning direction. The output signal are differentiated with a differentiating circuit 5. A differential output 5a undergoes binary coding in a binary circuit 6. A binary signal 6a from the circuit 6 and an inspection-range setting signal 7a from an inspection-range setting circuit 7 are inputted into an AND gate 8, in which an AND value is operated. An output signal 8a from the gate 8 is inputted into a pass-or- fail judging circuit 9, and the pass or fail of the state of the surface is judged. The detection of irregularities 2a which are yielded by the change in linear state of the multiple-line chart 1b projected on the surface, is ensured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a surface inspection device, and more specifically, the present invention relates to a surface inspection device, and more specifically, the surface inspection device illuminates the surface of an object to be inspected with inspection lighting, images the surface state with a television camera, and The present invention relates to a surface inspection device such as a defect detection device that processes a video signal to extract defects such as surface irregularities, scratches, and deposits to determine whether or not an object to be inspected is acceptable.

[Conventional technology]

One way to know the surface condition of an object to be inspected is to irradiate the object with a linear beam of light (slit-shaped beam of light) through a slit, and obtain information corresponding to the external shape from changes in the linearity of the beam. (photosection method).

Conventional surface inspection equipment using such a light cutting method is equipped with a light source device that irradiates a single slit-shaped light beam and a line sensor or area sensor for detecting the surface condition of the object to be inspected. There is.

However, in such a surface inspection device, since the slit-shaped light beam is one tree, it is necessary to perform 8 movements of the object to be inspected or oscillations of the light source device or optical system when detecting the surface condition. Since a driving device for relative movement is required, there is a problem in that the device becomes complicated.

In addition, such visual inspection equipment is configured to temporarily input sensor output as image information into a storage device and then process the stored information, but this increases the processing time. There are problems.

On the other hand, a large number of slit-like light beams are used, and the slit-like light beams and an imaging device (TV
This is a surface inspection device that can detect changes in the slit image at any time from the video signal by differentiating the video output signal synchronized with the horizontal scanning signal in parallel with the horizontal scanning line signal of the camera) in real time. There is a surface inspection device that is capable of real-time processing of video output signals from a TV camera and is also capable of inspecting a wide area.

[Problem that the invention seeks to solve]

However, when detecting defects such as scratches, deposits, and unevenness on the surface using a TV camera, especially when detecting unevenness defects, there are cases where there is no color change in the uneven part or the uneven shape is gentle. If so, it would have been difficult to detect.

The present invention provides a surface inspection device that can detect surface conditions quickly and reliably without complicating the device by making it possible to detect such defects using a TV camera. The purpose is to provide.

[Means for solving problems]

Therefore, the present invention includes an illumination device that illuminates the object to be inspected, an imaging device that images the illuminated surface of the object to be inspected, and a signal processing unit that extracts a signal according to the surface state by outputting a video. In a surface inspection device, slits with different transmittances are periodically arranged in an illumination device, and an imaging device is arranged so that the projected image of light irradiated onto the surface through the slits is parallel to the horizontal scanning direction of the imaging device. It is characterized by being arranged as follows.

[For production]

That is, in the present invention, for example, two types of slits having different transmittances are alternately arranged so that the surface of the object to be inspected is irradiated with two types of slit light beams having different intensities. Thereby, when irradiation is performed with slit light of the same intensity, it is possible to prevent surface conditions such as unevenness from being undetected due to changes in the linear condition of adjacent projected images. Further, by arranging the imaging device so that the horizontal scanning direction is parallel to the projected image, the video output can be processed in real time.

(Example〕 The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the invention. Here, 1 is an illumination unit having a multi-line chart la in which slits with different transmittances are arranged alternately, 2 is an object to be inspected, and 1b is a projected image of the multi-line chart irradiated by the illumination unit l. Note that 2a shows a projected image of a multi-line chart when there is a convex defect on the surface of the object to be inspected.

3 is a TV camera that images the surface of the object to be inspected 2 irradiated by the illumination unit 1 and the projected images 1b and 2a of the multiline chart; 4
is the video output signal of the TV camera 3, and the differential processing circuit 5
is input. 6 is 2 of the differential output 5a of the differential processing circuit 5
A binarization processing circuit performs digitization, 7 is an inspection range setting circuit that sets an inspection range related to pass/fail judgment, and 8 receives a binarization signal 6a and an inspection range setting signal 7a output from each section 6 and 7, respectively. This is an AND gate that calculates a logical product, and this outputs a binary number (No. 8 8a) within the inspection range set by the circuit 7. 9 is an AND gate that performs a pass/fail judgment on the surface condition for the AND output 8a. This is a judgment circuit.

Here, in this example, the TV camera 3 is arranged as follows.

FIG. 2 shows the imaging surface of the TV camera 3. 3b is a horizontal scanning signal, and when it is scanned horizontally as shown in this figure,
The TV camera 3 is arranged so that the multi-line chart 1b projected onto the surface of the inspected object 2 and the scanning direction of the horizontal scanning signal 3b are parallel to each other.

FIG. 3 is an image taken of the surface of the object 2 to be inspected in this arrangement and observed on a monitor (not shown), in which a change 4a in the chart due to a convex portion on the surface of the object 2 to be inspected is observed.

FIG. 4 shows an example of the waveforms of the output signals 4.5 to 8a of each part 3.5 to 8, and the operation of the apparatus according to this embodiment will be explained using this diagram.

First, the signal 4 shows the video signals 4b and 4c per horizontal scan in FIG. 3, and the period signal 4d is the signal 4b,
Period signal 4e corresponds to signal 4C. When such a signal is input to the differential processing circuit 5 as the video output signal 4, differential processing is performed and a differential signal 5a is obtained. In the figure, 4d and 4e1 indicate changes due to defective portions on the video signal, and 4d2 and 4e2 indicate defective portions after differential processing.

The signal 5a thus differentiated is sent to the binarization processing circuit 6.
When input manually, it is compared with a certain threshold voltage, and the output of the binarization circuit 6 is a digital signal that becomes H level when it is higher than the threshold voltage and becomes L level when it is lower than the threshold voltage. The signal 6a shown in FIG. 1, which is outputted, shows the binarized output when a predetermined positive voltage level is set as the threshold value 6b for the differential processing output signal 5a. Here, the threshold value is determined for the signal after differential processing, so it may be a positive voltage level (6b), or a negative voltage level 6C may be used as a threshold value. Also, with both 6b and 6C as thresholds, 2
Value conversion processing may also be performed. The output signal 6a thus binarized is supplied to one input terminal of the AND gate 8.

Here, when the video output signal 4a is differentiated and then binarized, the horizontal synchronization signal 4f1.4f2.4f contained in the video output signal is obtained.

Since differentiation and binarization processing are also performed on the vertical synchronization signal and the vertical synchronization signal, there is a possibility that that portion of the signal is output to the binarization output 6a. That is, there is a possibility that a signal unrelated to the image taken by the TV left camera will appear in the binarized output 6a, which will cause unreasonableness in performing the pass/fail determination process.

Therefore, in this example, the inspection range setting circuit 7 generates a signal for setting the range of the video signal necessary for the pass/fail judgment process, and supplies it to the other input terminal of the AND gate 8.
By calculating the logical product with the digitized output signal 6a, only the range necessary for the pass/fail judgment process in the binarized output signal 6a is provided for the pass/fail judgment as the AND output 8a.

Here, the horizontal synchronization signal 7b and vertical synchronization signal 7C of the TV left camera are input to the inspection range setting circuit 7 (see FIG. 1), and an inspection range output signal is output in synchronization with these signals. Therefore, it is also synchronized with the video output signal 4 of the TV left camera. Reference numeral 78 in the figure indicates an example of such an inspection range output signal. By doing this, the two input terminals of the AND gate 8 receive the signals 6a and 7 in FIG.
8 is manually input and a signal 8a is obtained as an AND output.

In other words, binarized output signals that are unnecessary for pass/fail judgment processing are removed, such as binarized outputs based on horizontal synchronization signals such as 4f1 to 4f3, and binarized outputs caused by video signal changes at the start and end of the horizontal video signal. The received signal is input to the pass/fail determination processing circuit 9.

Then, the pass/fail judgment processing circuit 9 counts the number of H level pulse signals of the AND gate output 8a within the range set by the inspection range setting circuit 7, compares it with the standard number of pulses, and determines the number of high-level pulse signals. If it is small, the object to be inspected can be determined to be defective, and if it is small, it can be determined to be good.

The present invention provides various parts 5.6, 7,
8 and 9 can also be modified as follows.

FIG. 5 is for explaining another embodiment of the present invention,
In this example, the video output signal 4 is binarized, the binarized output signal is temporarily stored in the image memory 50 while being synchronized with the horizontal and vertical synchronization signals of the television camera, and the stored data is processed. This method extracts defective parts and makes pass/fail judgments.

That is, for example, if a multi-line chart image is captured by a TV left camera, binarized, and stored in the memory 50 as shown in the figure, regularity of data according to the chart will be created in the memory 50. In other words, considering the horizontal direction, if all of the data contained in one row is "1" or "0", it can be determined to be correct, but if the data in one row is "0°" or "l" If this occurs, the regularity will be disrupted.Therefore, in the same manner as described above, this portion can be determined to be a defect such as unevenness.

That is, according to these embodiments, two types of slits with different transmittances are arranged alternately, that is, two types of slits with different strengths are arranged alternately.
In addition to irradiating the surface of the object to be inspected in a striped manner with different types of slit light beams, a TV camera was installed so that the scanning direction of the horizontal scanning signal was parallel to the multi-line chart projected on the surface. It is possible to prevent unevenness from being undetected, which may occur due to a change in the linear state of a close projected image when slit light is irradiated, and any unevenness can be reliably discovered. Further, since the test range is appropriately set by the setting circuit, there is no possibility of erroneously detecting signals that should not be tested.

In addition, by making the projected multi-line chart image parallel to the horizontal scanning direction of the TV camera 3, the video output signal 4 of the TV camera 3 can be processed in real time, and the time until pass/fail judgment processing is accelerated. can.

Furthermore, although the case where detection of irregularities is mainly performed is described above, by appropriately selecting the width and spacing of the slits with different transmittances, it is possible to detect dirt, particles, etc. other than irregularities in the slit parts with high transmittance. It becomes possible to detect the ground surface condition.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize a surface inspection apparatus that can quickly and reliably inspect the surface state of an object to be inspected without complicating the apparatus.

[Brief explanation of the drawing]

Fig. 1 is a line diagram showing one embodiment of the device of the present invention, Fig. 2 is an explanatory diagram for explaining the arrangement of the TV camera in the embodiment shown in the first drawing, and Fig. 3 is a diagram showing the arrangement of the TV camera in the embodiment shown in the first drawing. FIG. 4 is a waveform diagram showing the output signal waveform of each part to explain the operation of the apparatus shown in FIG. 1. FIG. FIG. 7 is an explanatory diagram for explaining another embodiment. l... Illumination unit, la... Multi-line chart, lb, 2a... Multi-line chart projected image, 2... Subject to be inspected, 3... TV camera, 4... Video output signal, 5... Differential processing circuit, 6... Binarization circuit, 7... Inspection range setting circuit, 8... Ant gate, 9... Pass/fail determination circuit, 50... Image memory.

Claims (1)

[Claims] A surface inspection device that includes an illumination device that illuminates an object to be inspected, an imaging device that images the illuminated surface of the object to be inspected, and a signal processing unit that extracts a signal according to the surface state by outputting the image. , slits with different transmittances are periodically arranged in the illumination device, and the imaging device is arranged such that a projected image of light irradiated onto the surface through the slits is parallel to a horizontal scanning direction of the imaging device. A surface inspection device characterized in that it is arranged so that.