JP3677885B2 - Sheet inspection equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention optically detects defects such as foreign matter, scratches, pinholes, etc. present in a sheet-like inspection object such as glass, resin, paper, etc. using a sensor such as a CCD linear image sensor or a laser type inspection machine. The present invention relates to an inspection device.
[0002]
[Prior art]
Conventionally, defects such as foreign matter, scratches and pinholes existing in optical films such as polarizing films and TFT color filters are irradiated with light from the light source 1 as shown in FIG. There is a method in which a CCD linear image sensor 3 receives light, an output signal from the sensor is detected by a detection means (not shown), and a defect present on the sheet is determined and detected as light contrast.
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 the sensor is focused on a specific place as described above. However, these inspection methods adjust the focal length of the sensor to the scattered light reflected on the film surface, so that the film placed on the belt is bent or uneven for some reason. When such a phenomenon occurs, it is detected as a defect. Therefore, the film at the inspection position must be located at the same distance from the sensor so as not to be out of focus.
[0003]
For example, a method using a breathable material for the belt and disposing a vacuum suction box below the belt passing through the inspection position, adsorbing the film passing through the inspection position from the lower belt, and injecting the film for inspection into close contact with the belt Can be considered. This method allows the belt to adsorb the film, so it can prevent the film from rolling up around the film. However, when the film (sheet) is large, the central part of the vacuum suction box bends downward from the peripheral part and reflects it. The image waveform is as shown in FIG. 5 and has a drawback that it is difficult to adjust the focal length.
[0004]
[Problems to be solved by the invention]
For the purpose of improving the above drawbacks, the present inventors used a 3 mm thick metal lath plate having a 2-5 mm diameter round hole in a vacuum suction box as shown in FIG. When the film to be inspected is thin, the film slightly bends downward in the center of the round hole, and the reflected image waveform is as shown in FIG. 4, and the difference from the case where there is a defect becomes unclear. However, the above-mentioned drawbacks of the method could not be solved completely.
Based on such knowledge, the present inventors find a sheet-type defect inspection apparatus that is inexpensive, excellent in operability, and highly accurate, which is always unaffected by size and thickness and has no problem with the focal length. As a result of intensive studies, the present inventors have found that 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 the sensor at a specific position, thereby completing the present invention. It came to.
[0005]
[Means for Solving the Problems]
That is, according to the present invention, a sheet-like inspection object is placed on a belt that moves in a certain direction, light is irradiated from the light source, and the reflected scattered light is received by the sensor. in the device for detecting, (1) the use of a breathable material to the belt, (2) the belt lower passing the inspection position, provided a plurality of rows with a plurality of holes or slits perpendicular to the traveling direction of the belt A vacuum suction mechanism having a top plate is provided, and a sheet-like inspection object passing through the inspection position is sucked from the lower part of the belt. (3) Between the holes formed in the top plate by the imaging unit (focal point) of the sensor or Rukoto is a light source and sensor are disposed as made between the slits, (4) the sensor is a CCD linear image sensor or laser type inspection apparatus, the sheet-like object to be inspected that is present on the top plate with no holes or slits Inspecting things , Shea characterized - to provide an inspection apparatus of bets like material.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic view showing a sheet inspection apparatus according to the present invention, and FIGS. 2 to 4 are schematic views showing a top plate structure of a vacuum suction mechanism B in contact with a belt 4. In FIG. 1, a polarizing film 2 that is a sheet-like inspection object is placed on a traveling belt and conveyed to an inspection position A. The inspection position A has a vacuum suction mechanism B composed of a vacuum suction box 5 and a top plate 6 at the lower part of the belt, and 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 inspection machine, and an output signal from the sensor is detected by a detection means (not shown). In this method, the defect is detected and judged as the brightness of the light.
[0007]
The present invention is characterized by the hole structure of the top plate 6 of the vacuum suction mechanism B. 2 and 3 show the top plate 6 used in the present invention. The top plate 6 shown in FIG. 2 is an example in which a plurality of rows of round holes 8 are continuously formed perpendicular to the running direction surface of the belt 4. FIG. 3 is an example having a plurality of rows of slits 7 perpendicular to the running direction surface of the belt. The number of holes, hole diameter, hole shape, slit width, 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, but usually has a hole diameter of 5 mm to 20 mm and a hole interval of 5 mm to What is necessary is just to implement in 15 mm and the range of the space | interval 5 mm-15 mm of each row | line | column. In the case of slits, the slit width may be 5 mm to 15 mm, and the interval between rows may be 5 mm to 15 mm.
[0008]
In the present invention, it is essential to install the light source 1 and the sensor 3 on the line A perpendicular to the running direction plane of the belt 4 in a state where the focus of the sensor is always in the space Y between the holes or slits. . With such a structure, the test position A is always for inspecting the sheet-like object to be inspected present on the top plate with no holes or slits in the top plate 6, Ya deflection into a sheet inspection object inspection position A Concavities and convexities are unlikely to occur, and the images are flat as seen in the reflected image waveforms of FIGS. The inspection position A may be between any slits Y to Yn ′ or between holes Y to Yn ′ formed on the top plate.
[0009]
The belt 4 used in the present invention may be any belt as long as the suction ability from the vacuum suction mechanism can reach the film 2 on the belt, and a polyethylene porous belt having a thickness of about 0.3 mm to 0.5 mm is usually used. . The color of the belt is not particularly limited, but usually gray is used. A polyethylene porous sheet 9 having a thickness of about 2 mm to 4 mm may be disposed between the top plate 6 of the vacuum suction box 5 and the belt 4 for the purpose of reducing resistance. Moreover, the material of the top plate 6 may be any of stainless steel, synthetic resin molding, ceramics, etc., and is not particularly limited.
The degree of vacuum in the vacuum suction box is usually in the range of about 70 mmHg to about 90 mmHg.
[0010]
【The invention's effect】
According to the present invention described above in detail, the top plate of the vacuum suction mechanism has a special structure, and the image pickup unit (focal point) of the sensor is merely disposed at a specific position, and the conventional known CCD is not complicated. The detection accuracy of an optical inspection apparatus using a linear image sensor or the like can be improved, and its industrial effect is extremely great.
[Brief description of the drawings]
FIG. 1 is a schematic view of an optical inspection apparatus 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 reflection image waveform using the vacuum suction mechanism.
FIG. 6 is a schematic view of an optical inspection apparatus using a CCD linear image sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light source 2 Sheet-shaped to-be-inspected object 3 Sensor 4 Belt 5 Vacuum suction box 6 Top plate 7 Slit 8 Round hole

Claims (1)

A device that places a sheet-like object on a belt that moves in a certain direction, irradiates light from the light source, receives reflected and scattered light with a sensor, and detects defects present in the sheet-like object. In
(1) Use a breathable material for the belt,
(2) the belt lower passing the inspection position, the sheet-like object to be disposed a vacuum suction mechanism having a top plate provided with a plurality of rows running side plurality of holes or slits perpendicular to the direction of the belt, pass through the inspection position Sucking the test object from the bottom of the belt
(3) Rukoto imaging unit of the sensor (focus) of the light source and sensor as will foramen or between slits bored in the top plate is arranged,
(4) The sensor is a CCD linear image sensor or a laser type inspection machine, and inspects a sheet-like inspection object existing on a top plate having no holes or slits,
A sheet defect inspection apparatus characterized by the above.

Images