JPH04309849A - Pinhole inspection device - Google Patents

Abstract

PURPOSE:To perform the inspection for pinholes in a short time without using a plurality of image pick-up devices. CONSTITUTION:A pinhole inspection device consists of a surface light source 1, screen 2, and an image pick-up device 3. The surface light source 1 irradiates a test object 4 from the back, and when pinholes exist on the test object 4, a magnified light image is formed on the screen 2 by the transmission light through the pinhole. The image pick-up device 3 is arranged at the upper position of the screen 2, and a dark screen 8 is arranged between the screen 2 and the image pick-up device 3. The light image on the screen 2 is image-picked- up by the image pick-up device 3, and an image signal is outputted into an image processing device.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is applicable to paper, rubber plates, etc.
The present invention relates to a pinhole inspection device used to inspect sheet-like objects such as plastic plates, metal plates, and ceramic plates for the presence or absence of minute pinholes.

0002

2. Description of the Related Art A conventional pinhole inspection device of this type is composed of an imaging device 20 and a surface light source 21, as shown in FIG. An inspection object 23 supported on a transparent support plate 22 is introduced. The surface light source 21 is composed of a diffusion plate 24 and a lamp light source 25, and the light from the lamp light source 25 is diffused by the diffusion plate 24, and the inspection object 23 is illuminated from behind by the diffused light.

0003

[Problems to be Solved by the Invention] Normally, in order to inspect a pinhole with a diameter of about 10 μm, it is necessary to set the observation field of the imaging device 20 to about 1 mm×1 mm. For example, if the inspection object 23 is square-shaped with a side of 30 cm, and the time required to inspect one screen is 0.1 seconds, it takes 300 x 300 x 0.1 =
The test takes a long time of 0.5 hours. In order to shorten this inspection time, it is necessary to prepare a plurality of imaging devices, which increases the equipment cost and makes it completely impractical.

The present invention has been made in view of the above problem, and an object of the present invention is to provide a pinhole inspection device that can shorten pinhole inspection time without using a plurality of imaging devices.

[0005]

[Means for Solving the Problems] A pinhole inspection device according to the present invention includes a surface light source, a screen, and an imaging device. An inspection position for introducing and inspecting an object to be inspected is set on the surface light source, a screen is placed opposite to the surface light source across the inspection position, and the imaging device is directed toward the screen. Place it and set the observation field.

[0006]

[Operation] When a pinhole exists in the object to be inspected, light from a surface light source passes through the pinhole, and an optical image is generated on the screen by the passing light. The imaging device places this optical image within the observation field and images it, but since the optical image is enlarged compared to the shape of the pinhole, the observation field of the imaging device can be set to a large size, and the inspection time can be shortened accordingly.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic configuration of a pinhole inspection apparatus according to an embodiment of the present invention, which is composed of a surface light source 1, a screen 2, and an imaging device 3. An inspection position for inspecting a sheet-shaped inspection object 4 is set on the surface light source 1, and the inspection object 4 supported on a transparent support plate 5 is guided to this inspection position.

The surface light source 1 includes a diffuser plate 6 and a lamp light source 7.
The light from the lamp light source 7 is diffused by the diffuser plate 6, and the inspection object 4 is illuminated from behind by the diffused light.

A screen 2 is arranged parallel to and opposite the surface light source 1 across the inspection position and at an appropriate distance from the inspection position, and the image pickup device 3 is arranged on the screen 2 facing downward. Set the observation field including the transmitted light image described later.

The imaging device 3 is for capturing a transmitted light image on the screen 2. The imaging device 3 captures the transmitted light image and outputs the image signal to an image processing device (not shown). This image processing device binarizes an input image, processes the binary image, and determines the presence or absence of a pinhole.

A blackout curtain 8 is arranged around the screen 2 between the image pickup device 3 and the screen 2,
This blackout curtain 8 prevents ambient light from being irradiated onto the screen 2. A semi-translucent plate material such as a diffuser plate is used as the screen 2, but when the imaging device 3 is positioned below the screen 2 to capture a reflected light image on the screen 2, a non-translucent plate material is used. It may be of. In this case, since it is not easy to provide the blackout curtain 8, it is necessary to darken the surrounding environment.

[0012] In the pinhole inspection device having the above configuration,
Now, the inspection object 4 is supported on the transparent support plate 5 and guided to the inspection position, and an imaging operation is performed by the imaging device 3 under back illumination by the surface light source 1.

If a pinhole exists in the inspection object 4, the light emitted from the surface light source 1 passes through the pinhole 13 of the inspection object 4 and illuminates the lower surface of the screen 2, as shown in FIG. A portion of the irradiated light passes through the screen 2 and generates a transmitted light image 9 on the upper surface of the screen 2. In this case, since there is an appropriate distance between the inspection object 4 and the screen 2, the transmitted light image 9 is enlarged and the pinhole 13
The outer shape is larger than that of .

When this transmitted light image 9 is captured by the imaging device 3 and its gray scale image is taken into the image processing device,
The image processing device binarizes the grayscale image to generate a binary image 10 as shown in FIG.

In FIG. 3, reference numeral 11 indicates a white pixel area which is the image part of the transmitted light image 9, and 12 indicates a black pixel area which is the image part of the surrounding area of the transmitted light image 9. The device counts the number of white pixels constituting the white pixel area, and when the counted value exceeds a predetermined threshold value, determines that the white pixel area 11 is the transmitted light image 9 of the pinhole 13.

Assuming now that the diameter of the pinhole 13 is 10μ, and the diameter of the transmitted light image 9 is expanded to 100μ, the observation field of the imaging device 3 will be 10mm x 10mm.
It can be set to a certain degree. In this case, if the inspection object 4 is a square with a side of 30 cm, and the time required to inspect one screen is 0.1 seconds, it will take 90 minutes to inspect the entire surface of the inspection object 4.
The inspection time is only 1/2 seconds compared to conventional methods.
It becomes 100.

[0017]

Effects of the Invention As described above, the present invention sets an inspection position for introducing and inspecting an object onto a surface light source, and arranges a screen opposite to the surface light source across the inspection position. Since the observation field is set by arranging the imaging device facing the screen, it is possible to enlarge and photograph the outline of the pinhole that the inspection object has on the screen. Therefore, it is possible to set a large observation field of the imaging device, and pinholes can be inspected in a short time without using a plurality of imaging devices, resulting in the effect that the pinhole inspection time can be significantly shortened.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a pinhole inspection device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a situation in which light from a surface light source passes through a pinhole.

FIG. 3 is an explanatory diagram showing a binary image of a transmitted light image.

FIG. 4 is a sectional view showing a schematic configuration of a conventional example.

[Explanation of symbols]

1　　　　　　　　　Surface light source 2 Screen 3 Imaging device

Claims (1)

[Claims] 1. A pinhole inspection device for inspecting the presence or absence of pinholes in an object to be inspected, comprising a surface light source, a screen, and an imaging device, and on the surface light source:
Set the inspection position for introducing and inspecting the inspection target,
A pinhole inspection device, wherein a screen is disposed opposite to the surface light source with the inspection position in between, and the imaging device is disposed facing the screen to set an observation field.