JPH1062146A - Defect examining device of sheet-shaped object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the detection accuracy of an optical examining device using a CCD linear image sensor, etc., by providing a light source and sensor so as to locate the point (focal point) that the sensor picks up an image between holes or slits formed in a top plate. SOLUTION: A vacuum suction mechanism B with a top plate 6 is provided under a belt 4 of air permeable material over which a sheet-shaped object to be measured 2 is conveyed. A plurality of holes or slits are provided on the top plate 6 in a plurality of rows orthogonal to the direction of the movement of the belt 4. The sheet-shaped object to be measured 2 passing through an examination point is attracted from the lower part of the belt 4. A light source 1 and sensor 3 are arranged in a line A orthogonal to the direction of the movement of the belt 4 so as to locate the focal point (location of examination) of the sensor 3 at any space Y between the rows of the holes or slits at all times. By this, flexure and irregular surfaces hardly occur on the sheet- shaped object to be examined 2 at the location of examination, and as an image which the sensor 3 forms from the reflected and scattering light received from the light source 1 is flat, the false detection of defects is reduced to improve detection accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a sensor such as a CCD linear image sensor or a laser type inspection device to detect defects such as foreign matter, scratches and pinholes present on a sheet-like inspection object such as glass, resin and paper. The present invention relates to an optical inspection device that performs electronic detection.

[0002]

2. Description of the Related Art Conventionally, defects such as foreign matter, scratches and pinholes existing in an optical film such as a polarizing film or a TFT color filter are irradiated with light from a light source 1 as shown in FIG.
The scattered and reflected light from the sheet-like inspection object 2 is received by the CCD linear image sensor 3, and an output signal from the sensor is detected by detection means (not shown), and a defect existing on the sheet is determined and detected as light brightness. The way has been done. When these are inspected industrially, in a series of manufacturing processes, a sheet-like inspection object such as a film is placed on a belt moving in a certain direction, and a sensor is focused on a specific place, and the above-described operation is performed. Inspections are performed by these methods, but these inspection methods adjust the focal length of the sensor to the scattered light reflected on the film surface. When such a phenomenon occurs, the film is detected as a defect. Therefore, the film at the inspection position needs to be positioned at the same distance from the sensor so that the focus is not deviated.

For example, a breathable material is used for the belt, and a vacuum suction box is provided below the belt passing through the inspection position. The film passing through the inspection position is sucked from the lower portion of the belt, and the film to be used for inspection is brought into close contact with the belt. An inspection method is conceivable. In this method, the film is attracted to the belt, so that winding around the film can be prevented. However, when the film (sheet) is large, the central portion of the vacuum suction box deflects lower than the peripheral portion, and its reflection is caused. The image waveform is as shown in FIG. 5, and has a drawback that the focal length is difficult to match.

[0004]

In order to improve the above drawbacks, the present inventors mounted a 3 mm thick metal lath plate having a circular hole of 2 to 5 mm diameter in a vacuum suction box as shown in FIG. When the film to be inspected was thin, the film slightly bent downward at the center of the round hole, and the reflected image waveform was as shown in FIG. In this case, the difference from the above case is not clear, and the above-mentioned disadvantages of the method cannot be completely solved. Based on such knowledge, the present inventors have found a low-cost, excellent operability and high-accuracy sheet defect inspection apparatus which is not affected by the size and thickness and always has no problem in focal length. As a result of intensive studies, it was found that all of the above problems can be solved by a simple method of devising the shape of the top plate laid in the vacuum suction box and disposing a sensor at a specific position, and completing the present invention. Reached.

[0005]

That is, according to the present invention, a sheet-like inspection object is placed on a belt moving in a certain direction, and light is radiated from a light source on the inspection object, and reflected and scattered light is received by a sensor. In a device for detecting a defect present in a sheet-like inspection object, (1) using a breathable material for a belt;
(2) A vacuum suction mechanism having a top plate provided with a plurality of rows or a plurality of holes or slits perpendicular to the running direction of the belt is provided below the belt passing the inspection position, and the sheet-like cover passing the inspection position is provided. Sucking the inspection object from the lower part of the belt,
(3) A sheet-like defect inspection apparatus characterized in that a light source and a sensor are arranged such that an imaging section (focus) of the sensor is between holes or slits formed in a top plate. To be.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic view showing a sheet-like defect inspection apparatus of the present invention, and FIGS. 2 to 4 are schematic views showing a top plate structure of a vacuum suction mechanism 5 which comes into contact with a belt 4.
In FIG. 1, a polarizing film 2 which is a sheet-like inspection object is placed on a running belt and transported to an inspection position A. The inspection position A has a vacuum suction mechanism B including a vacuum suction box 5 and a top plate 6 at the lower part of the belt. The polarizing film conveyed by the belt is sucked from the lower part of the belt and brought into close contact with the belt. The light irradiated from 1 is received as reflected and scattered light by a sensor 3 such as a CCD linear image sensor or a laser-type inspection machine, and an output signal from the sensor is detected by a detecting means (not shown). In this method, a defect is detected and judged as the brightness of the light.

In the present invention, the top plate 6 of the vacuum suction mechanism B is used.
It is characterized by the pore structure of 2 and 3 show a top plate 6 used in the present invention. The top plate 6 shown in FIG. 2 has an example in which a plurality of rows of round holes 7 are continuously provided perpendicular to the running direction surface of the belt 4. FIG. 3 shows an example in which a plurality of rows of slits 8 are provided perpendicular to the running direction surface of the belt. The number of the holes,
The hole diameter, the shape of the holes, the width of the slits, the number of rows, and the like are not particularly limited as long as the film placed on the belt is in close contact with the belt, and the hole diameter is usually 5 mm to 20 mm, and the hole interval is 5 mm.
It may be carried out within a range of １５15 mm and an interval of each row of 5 mm１５15 mm. In the case of a slit, the width of the slit is 5m
m to 15 mm, and the interval between each row may be 5 to 15 mm.

In the present invention, the light source 1 and the sensor 3 are set on the line A perpendicular to the running direction of the belt 4 in a state where the sensor is always focused between the rows Y of the holes or the slits. Required. By adopting such a structure, the inspection position A always inspects a film portion existing on a flat plate having no holes or slits in the top plate 6, so that the film portion at the inspection position A is unlikely to be bent or uneven. , FIG.
As can be seen from the reflected image waveform, the image is flat, so that there is little false recognition and the detection accuracy is improved. Test position A may be between any slit formed in the top plate Y~Y n ^'or Anakan Y~Y ^n'.

The belt 4 used in the present invention may be any belt as long as the suction capability from the vacuum suction mechanism can reach the film 2 on the belt. A porous belt made of polyethylene having a thickness of about 0.3 mm to 0.5 mm is usually used. used. The color of the belt is not particularly limited, but gray is usually used. A polyethylene porous sheet 9 having a thickness of about 2 mm to 4 mm may be provided between the top plate 6 and the belt 4 of the vacuum suction box 5 for the purpose of reducing the resistance. The material of the top plate 6 may be any of stainless steel, synthetic resin molded body, ceramics, and the like.
There is no particular limitation. The degree of vacuum in the vacuum suction box is usually in the range of about 70 mmHg to about 90 mmHg.

[0010]

According to the present invention described in detail above, the top plate of the vacuum suction mechanism has a special structure, and the imaging section (focal point) of the sensor is disposed at a specific position, without complicating any operation. The detection accuracy of an optical inspection device using a conventionally known CCD linear image sensor or the like can be improved, and the industrial effect is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an optical inspection device using a CCD linear image sensor.

FIG. 2 is a schematic diagram showing a hole structure of a top plate of a vacuum suction mechanism and a reflected image waveform using the same.

FIG. 3 is a schematic diagram showing a hole structure of a top plate of a vacuum suction mechanism and a reflected image waveform using the same.

FIG. 4 is a schematic diagram showing a hole structure of a top plate of a vacuum suction mechanism and a reflected image waveform using the same.

FIG. 5 is a schematic diagram showing a vacuum suction mechanism without a top plate and a reflected image waveform using the same.

FIG. 6 is a schematic diagram of an optical inspection device using a CCD linear image sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Sheet-like inspection object 3 Sensor 4 Belt 5 Vacuum suction box 6 Top plate 7 Round hole 8 Slit

Claims (2)

[Claims] 1. A sheet-like inspection object is placed on a belt moving in a certain direction, light is radiated from a light source, reflected scattered light is received by a sensor, and a defect existing in the sheet-like inspection object is detected. (1) Use of a breathable material for the belt, and (2) A plurality of rows or slits are provided below the belt passing through the inspection position in a direction perpendicular to the running direction of the belt. Arrange a vacuum suction mechanism with a top plate,
(3) A light source and a sensor are arranged such that an imaging unit (focal point) of the sensor is located between holes or slits formed in a top plate, and the sheet-like inspection object passing through the inspection position is sucked from a lower portion of the belt. A sheet-like defect inspection apparatus, comprising: 2. The sheet defect inspection apparatus according to claim 1, wherein the sensor is a CCD linear image sensor or a laser inspection machine.