JP4620228B2 - Light scattering transmission sheet defect inspection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of optically inspecting a sheet for defects. In particular, the present invention relates to a defect inspection apparatus that can detect both foreign matter defects and light scattering defects in a light-scattering transmission sheet in a single inspection.
[0002]
[Prior art]
One of the main drawbacks of the light scattering transmission sheet is that the light scattering characteristics deviate from predetermined characteristics. In particular, light scattering unevenness in which the light scattering characteristics vary depending on the sheet portion is a problem. One of the main drawbacks is foreign matter contained in the light scattering transmission sheet. Some of these foreign substances are contained in the original material, and some are attached and mixed in the manufacturing process. In the light-scattering / transmitting sheet, since optical characteristics are regarded as particularly important, any defect is regarded as a heavy defect.
[0003]
[Problems to be solved by the invention]
Conventionally, the defect inspection of the light-scattering / transmitting sheet is performed exclusively by visual inspection. This is because it is extremely difficult to detect foreign matter where light scattering exists and to detect subtle light scattering itself by mechanical detection. However, for humans, this test is always stressed and focused, has a heavy workload, requires a lot of time, and is costly. Furthermore, as long as human inspections are performed, variations in inspection standards and oversight of defects are inevitable.
[0004]
The present invention has been made to solve such problems. The object is to provide a defect inspection apparatus capable of detecting both foreign matter defects and light scattering defects in a light scattering transmission sheet with high sensitivity and high speed by a single inspection.
[0005]
[Means for Solving the Problems]
The above problems are solved by the present invention described below. That is, the defect inspection apparatus according to claim 1 of the present invention is an inspection apparatus for inspecting the presence or absence of defects in a transported light scattering transmission sheet, and includes a line sensor camera, a line light source, and a strip-shaped light control member. The line sensor camera has a line-shaped imaging region, and an angle formed between the imaging optical axis and the surface of the light scattering transmission sheet is an acute angle of ∠20 ° to ∠70 °. And scanning in the direction perpendicular to the direction of transport of the light scattering transmission sheet and imaging the light scattering transmission sheet to output an imaging signal,
The line-shaped light source is a light source having a line-shaped light emitting region for the line sensor camera to pick up an image with light rays scattered and transmitted through the scattering transmission sheet, and the direction of the light emitting region and the direction of the imaging region are parallel. Is provided at a position on the non-imaging side of the light scattering transmission sheet at a position on the side away from the extension of the imaging optical axis of the line sensor camera and looking at the acute angle from the opposite side, A band-shaped member having a black and matte surface for adjusting light incident on the imaging region of the line sensor camera from the back side of the light scattering transmission sheet, the direction of the member and the imaging region The direction is a parallel direction, and on the extension of the imaging optical axis of the line sensor camera, the surface is provided so as to be parallel to the surface of the light scattering transmission sheet. Than is.
[0006]
According to the present invention, the line sensor camera that scans the light scattering transmission sheet by scanning in the direction perpendicular to the transfer direction of the light scattering transmission sheet, and the line sensor camera images the scattering transmission sheet with the light that is scattered and transmitted. The defect inspection apparatus is composed of a line-shaped light source having a line-shaped light emitting region and a strip-shaped light adjusting member having a black and matte surface . With this configuration, both the foreign matter defect and the light scattering defect in the light scattering transmission sheet are detected with extremely high sensitivity and high speed in one inspection.
[0010]
A defect inspection apparatus according to claim 2 of the present invention is the defect inspection apparatus according to claim 1 or 2, further comprising a data processing unit, and the data processing unit detects at least a foreign object defect in the light scattering transmission sheet. And a process for detecting a light scattering defect, and a detection result is output so that the contents of the defect can be understood. According to the present invention, the detection result is output so that the content of the defect can be understood.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described. An example of the configuration of a detection system in the defect inspection apparatus of the present invention is shown in FIG. In FIG. 1, 1 is a line sensor camera, 2 is a line-shaped light source, 3 is a strip-shaped auditory member, and 100 is a light scattering transmission sheet. Moreover, the arrow (→) indicates the transfer direction of the light scattering transmission sheet 100. In FIG. 1, the light scattering transmission sheet 100 is transferred from the left side to the right side, but this transfer direction is the same even if the transfer direction is the reverse direction.
[0012]
The line sensor camera 1 is a camera having a line-shaped imaging region. For example, it is a camera using a photosensor such as a charge coupled device (CCD) type or a metal oxide semiconductor (MOS) type in which a large number of light receiving pixels (about 500 to 5000) are arranged one-dimensionally. The line sensor camera 1 scans the light receiving pixels arranged in one dimension and outputs an imaging signal. As shown in FIG. 1, the line sensor camera 1 is installed in the detection system so that the scanning direction is a direction perpendicular to the transport direction of the light scattering transmission sheet 100.
[0013]
The angle formed by the imaging optical axis of the line sensor camera 1 and the surface of the light scattering / transmitting sheet 100 is suitable for many types of light scattering / transmitting sheets 100 when the angle is in the range of ∠20 ° to ∠70 °. A specific value in this range is appropriately determined according to the light scattering transmission sheet 100 to be inspected. By installing in this way, it becomes possible to detect both the foreign substance defect and the light scattering defect in the light scattering transmission sheet 100 with high sensitivity.
[0014]
The line-shaped light source 2 is a light source having a line-shaped light emitting region. For example, a straight tube-shaped light source such as a fluorescent lamp, a neon tube, a xenon lamp, or a halogen lamp can be applied. In addition, it is possible to apply one in which a linear light emitting region is formed using an optical fiber, a light transmission member, a lens, or the like. Further, it is possible to apply one in which point light sources such as LEDs (light emitting diodes) are arranged one-dimensionally to form a pseudo linear light emitting region.
[0015]
The line light source 2 is installed such that the direction of the light emitting area and the direction of the imaging area of the line sensor camera 1 are parallel to each other. The line light source 2 is a light source for the line sensor camera 1 to take an image with light rays scattered and transmitted through the scattering transmission sheet 100. Therefore, as shown in FIG. 1, the light scattering transmission sheet 100 is installed at a position on the non-imaging side.
[0016]
As shown in FIG. 1, the linear light source 2 is installed at a position on the side where the acute angle formed by the imaging optical axis of the above-described line sensor camera 1 and the surface of the light scattering transmission sheet 100 is viewed from the opposite side. . Further, the line light source 2 is installed away from the extension of the imaging optical axis of the line sensor camera 1. By installing in this way, it becomes possible to detect both the foreign substance defect and the light scattering defect in the light scattering transmission sheet 100 with high sensitivity.
[0017]
The strip-shaped light adjusting member 3 is a strip-shaped member for adjusting the light beam incident on the imaging region of the line sensor camera 1 from the back side of the light scattering transmission sheet 100. As shown in FIG. 1, the strip-shaped light adjusting member 3 and the imaging region are installed so that the direction of the strip-shaped light control member 3 is parallel to the direction of the imaging region and the extension of the imaging optical axis of the line sensor camera 1.
[0018]
The strip-shaped light control member 3 is preferably a black and matte surface. Further, it is preferable that the strip-shaped light adjusting member 3 is installed so that the surface thereof is parallel to the surface of the light scattering transmission sheet 1. By doing in this way, adjustment of the light beam by the strip | belt-shaped light control member 3 can be performed effectively. As a result, it is possible to detect both foreign matter defects and light scattering defects in the light scattering transmission sheet 100 with high sensitivity.
[0019]
The light beam incident on the line-shaped imaging region of the line sensor camera 1 is a light beam emitted from the line-shaped light source 2. However, since the light-scattering / transmitting sheet 100 scatters and transmits the light, the light incident on the imaging region becomes a very complicated light. According to the above arrangement, the line sensor camera 1 does not directly capture the light emitted from the linear light source 2 (not directly receive light). The line sensor camera 1 images the light scattering transmission sheet 100. However, depending on the degree of light scattering, the background side of the light scattering transmission sheet 100 is also imaged at the same time. When the light scattering transmission sheet 100 can be regarded as a transparent sheet with very little light scattering, the line sensor camera 1 captures the surface of the band light control member 3 when the band light control member 3 is present.
[0020]
Light rays scattered from a wide area of the light-scattering / transmitting sheet 100 reach the surface of the strip-shaped light control member 3. That is, the brightness of the surface of the strip-shaped light adjusting member 3 changes or varies depending on the optical characteristics of a wide area of the light scattering transmission sheet 100. As a result, the imaging signal of the line sensor camera 1 includes not only the optical characteristics of the imaging area that the line sensor camera 1 intends to image, but also the influence of a wide area of the light scattering transmission sheet 100 as a disturbance. . One of the reasons for making the strip-shaped light control member 3 a black and matte surface and making the surface parallel to the surface of the light scattering transmission sheet 1 is to avoid this disturbance.
[0021]
Of course, the strip-shaped light adjusting member 3 has a role of shielding the light beam emitted from the background side of the light scattering transmission sheet 100 so that the line sensor camera 1 does not directly capture the light beam. The presence of the strip-shaped light control member 3 prevents the background side behind the strip-shaped light control member 3 from being disturbed.
[0022]
In the foregoing, it has been described that the line sensor camera 1 does not directly image the light emitted by the line light source 2. However, the actual line light source 2 is not a light source that emits light with an ideal line but has a corresponding light emitting area. In addition, since the light-scattering / transmitting sheet 100 scatters and transmits the light, the light incident on the imaging region is a very complicated light. Therefore, although the line light source 2 is installed away from the extension of the imaging optical axis of the line sensor camera 1, the light beam captured by the line sensor camera 1 is substantially not only a scattered light beam but also substantially a scattered light beam. Components that can be regarded as direct rays are included.
[0023]
The strip-shaped light control member 3 can adjust the component ratio of the scattered light and the direct light. When the extent to which the line-shaped light source 2 is hidden by the strip-shaped light adjusting member 3 is increased, the component ratio of scattered light increases. If the extent to which the line-shaped light source 2 is hidden is reduced by the strip-shaped light adjusting member 3, the component ratio of the direct light increases. By optimizing the component ratio of the scattered light and the direct light, it is possible to detect both the foreign matter defect and the light scattering defect in the light scattering transmission sheet 100 with high sensitivity.
[0024]
Next, processing of the imaging signal output from the line sensor camera 1 will be described. An example of the configuration of the processing system in the defect inspection apparatus of the present invention is shown in FIG. In FIG. 2, the same parts as those in FIG. In FIG. 2, 4 is a main body of the processing system, 5 is an input unit, and 6 is an output unit. In the main body 4 of the processing system, 41 is an A / D (analog-to-digital) conversion unit, 42 is a storage unit, and 43 is a processing unit.
[0025]
The main body 4 is a main body of a data processing apparatus such as a personal computer or an image processing system. The processing system in the defect inspection apparatus of the present invention can be constituted by hardware and software of a data processing apparatus and peripheral devices. The input unit 5 is a part where an operator performs setting input, instruction input, and the like for the defect inspection apparatus. The input unit 5 includes a keyboard, a mouse, and the like, for example. The output unit is a part that outputs setting contents, operation states, inspection results, and the like in the defect inspection apparatus. An output part consists of a display, an alarm device, etc., for example.
[0026]
An imaging signal output from the line sensor camera 1 is input by the A / D converter 41 of the main body 4. The imaging signal is an imaging signal obtained by the line sensor camera 1 scanning in the direction perpendicular to the transfer direction of the light scattering transmission sheet 100 and imaging the light scattering transmission sheet. The A / D conversion unit 41 converts the imaging signal into digital data and stores it in the storage unit 42.
[0027]
The number of scanning lines (one scanning signal) in the stored imaging signal is not limited to one, and the number of scanning lines to be processed simultaneously (associated) differs depending on the type and size of the defect to be detected. In general, in the case of a small dot-like defect, the number of scanning lines to be processed simultaneously is small. Further, in the case of a defect extending over a wide area, it is necessary to increase the number of scanning lines to be processed simultaneously.
[0028]
Therefore, the data of the imaging signal stored in the storage unit 42 is two-dimensional data obtained by imaging a specific part in the light scattering transmission sheet 100, that is, image data. The image data stored in the storage unit 42 is updated as the light scattering transmission sheet 100 is transferred. In order to update continuously, for example, the storage unit 42 is divided into two or more regions so that reading of new image data and data processing for defect detection do not occur simultaneously in the same region.
[0029]
Based on the image data stored in the storage unit 42, the processing unit 43 performs a process of detecting a defect. The processing unit 43 performs at least processing for detecting foreign matter defects in the light scattering transmission sheet 100 and processing for detecting light scattering defects. Many foreign object defects have small dimensions. As a process for detecting a small defect, for example, image data is differentiated using a Laplacian operator or the like, and binarized with a predetermined threshold value. Small light scattering defects can be detected by the same process.
[0030]
Many light scattering defects cover a wide area. As a process for detecting a defect in a wide area, a process for removing errors such as shading and other wide-area imaging unevenness included in image data is performed to determine whether or not the image is included in a predetermined allowable range. Large foreign object defects can be detected by the same process.
It should be noted that reference image data may be obtained before inspection, and error removal and detection may be performed at the same time by calculating the difference between them.
[0031]
The detection result in the processing unit 43 is output in the output unit 6 so that the content of the defect can be understood.
[0032]
【The invention's effect】
As described above, according to the defect inspection apparatus of the first aspect of the present invention, both the foreign matter defect and the light scattering defect in the light scattering transmission sheet are detected with extremely high sensitivity and high speed by one inspection. be able to. According to the defect inspection apparatus of the second aspect of the present invention, the detection result can be output so that the contents of the defect can be understood.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of a configuration of a detection system in a defect inspection apparatus for a light scattering transmission sheet according to the present invention.
FIG. 2 is a diagram showing an example of a configuration of a processing system in a defect inspection apparatus for a light scattering transmission sheet according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Line sensor camera 2 Line-shaped light source 3 Band-shaped auditory member 4 Processing system main body 5 Input part 6 Output part 41 A / D conversion part 42 Storage part 43 Processing part 100 Light scattering transmission sheet

Claims (2)

A defect inspection apparatus for inspecting the presence or absence of defects in the transported light-scattering transmission sheet, comprising a line sensor camera, a line-shaped light source, and a strip-shaped light control member,
The line sensor camera has a line-shaped imaging region, and an angle formed between the imaging optical axis and the surface of the light scattering transmission sheet is an acute angle of の 20 ° to ∠70 °, and the light Scanning in the direction perpendicular to the transport direction of the scattering transmission sheet and imaging the light scattering transmission sheet to output an imaging signal,
The line-shaped light source is a light source having a line-shaped light emitting region for the line sensor camera to pick up an image with light rays scattered and transmitted through the scattering transmission sheet, and the direction of the light emitting region and the direction of the imaging region are parallel. The light scattering transmission sheet is provided at a position on the non-imaging side of the light scattering transmission sheet and on the side where the acute angle is viewed from the opposite side away from the extension of the imaging optical axis of the line sensor camera,
The band-shaped light adjusting member is a band-shaped member having a black and matte surface for adjusting light rays incident on the imaging region of the line sensor camera from the back side of the light scattering transmission sheet, The direction and the direction of the imaging region are parallel directions, and are provided on the extension of the imaging optical axis of the line sensor camera so that the surface thereof is parallel to the surface of the light scattering transmission sheet.
A defect inspection apparatus characterized by that. The defect inspection apparatus according to claim 1, further comprising a data processing unit, wherein the data processing unit performs at least processing for detecting foreign matter defects in the light scattering transmission sheet and processing for detecting light scattering defects, and results of detection. Is output so that the content of the defect can be understood.

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