JPH06242024A - Defect inspection system for sheet material - Google Patents

Abstract

PURPOSE:To detect defect on a sheet material running under such state as the range of vertical movement is larger than the depth of focus of an image input unit by moving the image input unit up and down over a range wider than that for the running sheet material. CONSTITUTION:Displacement sensors 1, 2 measure displacement of a sheet material 3 where the sensor 1 is turned ON when the surface of the sheet material 3 is present within the focus point + or - depth of focus of an image input unit 4 whereas the sensor 2 is turned ON when the rear of the sheet material 3 is present within the focal point + or - depth of focus of the unit 4. Up/down motion range of the unit 4 must be wider than the up/down motion range + thickness of the sheet material 3. Upon receiving signals from the sensors 1, 2, an image processor 5 delivers an actuation signal to a strobe illuminator 7. When light is projected from the illuminator 7, substantially still image of the sheet material 3 is inputted from the unit 4. The image processor 5 determines the number of defects, size, etc., from the image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection device for inspecting a defect state of a sheet-like object which is traveling with a vertical movement range larger than a depth of focus of an image input device.

[0002]

2. Description of the Related Art As an apparatus for inspecting defects of a sheet-like object, for example, an image input device (CCD camera) for inputting an image of a traveling sheet-like object, an illuminating device such as stroboscopic light emission or a light guide, and image processing. There has been proposed a defect inspection device for a sheet-like object composed of the device.

[0003]

In the prior art, inspecting the state of defects of a sheet-like object traveling in a state where the vertical movement range is larger than the depth of focus of the image input device is the focus of the image input device. Due to the greater up and down range than depth, inspection was virtually impossible.

The present invention has been made on the basis of the above background, and an object of the present invention is to eliminate defects of a sheet-like object which is traveling in a state where the vertical movement range is larger than the depth of focus of the image input device. An object of the present invention is to provide a defect inspection device for a sheet-like object that can be inspected.

[0005]

According to the present invention, the conventional problems have been solved by moving the image input device up and down and inspecting the image at the in-focus position. That is, the defect inspection device for a sheet-like object according to the present invention,
When the distance between the image input device that moves up and down in a range larger than the vertical movement range and the sheet and the image input device is the in-focus position ± focal depth, an inspection start signal is output to the image processing device. A displacement sensor, a strobe lighting device that emits strobe light when the inspection start signal is output, a ring-shaped optical fiber light guide that is installed between the image input device and the sheet-like object to perform reflection illumination, and an image processing device. It will be.

In a preferred embodiment of the present invention, the use of two series of displacement sensors makes it possible to inspect defects on the front and back surfaces of a transparent sheet-like object with a single image input device.

The image input conditions are as follows. The vertical movement range of the image input device satisfies the following condition. D> (L + t) D: Vertical movement range of image input device H: Focusing position (distance from image input device to sheet-like object) L: Vertical movement range of sheet-like object t: Thickness of sheet-like object f: When the front and back of the image input device are inspected separately, the condition of the following formula is satisfied. If not satisfied, there is a possibility that defects on both sides will be detected at the same time. t> 2f Displacement sensor condition For surface inspection: ON when H ± f For back surface inspection: ON when H + t ± f

[0008]

The device according to the present invention having the above construction operates as follows. The sheet is transparent and has a thickness of t
Therefore, the vehicle is traveling in the vertical movement range L. The displacement sensor is
The displacement sensor measures the displacement with the sheet-like object, and the displacement sensor turns on when the front surface of the sheet-like object reaches the focus position ± depth of focus of the image input device, and the second displacement sensor detects the rear surface of the sheet-like object. , ON when the in-focus position of the image input device ± focus depth is reached.

The vertical movement range of the image input device is larger than the vertical movement range of the sheet-like material + the sheet thickness of the sheet-like material. When the signal from the displacement sensor is input to the image processing device, the image processing device outputs a signal to the strobe lighting to the strobe lighting, and light is emitted through the optical fiber light guide and the strobe lighting emits light. An image of the sheet-like material is input from the image input device. From this image, the number and size of defects are measured by the image processing device.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing an example of the apparatus configuration of the present invention. The apparatus according to this embodiment includes a traveling sheet-like material 3
When the distance between the image input device 4 that moves up and down in a range larger than the vertical movement range and the sheet-like object and the image input device is the in-focus position ± focal depth, an inspection start signal is sent to the image processing device. Displacement sensors 1 and 2 that output, and a strobe lighting device 7 that emits strobe light when an inspection start signal is output,
It is composed of a ring-shaped optical fiber light guide 8 which is installed between the image input device and the sheet-like object to perform reflection illumination, and the image processing device 5. In this aspect, the distance between the sheet-like object and the image input device is equal to each other. When the focus position is ± focal depth and the in-focus position + plate thickness ± focal depth, two series of displacement sensors 1 and 2 that output an inspection start signal to the image processing apparatus are used.

The inspection by this device is performed in the following procedure. The sheet 3 is transparent and has a thickness of several mm,
It runs at a vertical range of several mm and a running speed of several m / min. The displacement sensors 1 and 2 measure the displacement with respect to the sheet-like material 3. The displacement sensor 1 is turned on when the front surface of the sheet-shaped object 3 is at the focus position ± the depth of focus of the image input device 4, and the displacement sensor 2 is the rear surface of the sheet-shaped object 3 when the image input device 4 is focused. It is turned ON when the position ± depth of focus is reached.

The image input device 4 uses a CCD camera, and the lens is a long focus macro lens (f = 110 mm,
F = 16) is used. The image input conditions are a resolution of 10 μm / pixel and a depth of focus of ± 0.2 mm.
Further, since the vertical movement range of the image input device 4 needs to be larger than (the vertical movement range of the sheet-shaped material + the plate thickness of the sheet-shaped material), the vertical movement is repeated within the range of 20 mm. Therefore, even if the type of the sheet-like material 3 is changed and the sheet 3 is moved up and down, the state in which the in-focus position is within the vertical movement range of the image input device 4 is included. When the signals from the displacement sensors 1 and 2 are input to the image processing apparatus 5, the image processing apparatus 5 outputs a signal for causing the strobe to emit light.
Output to the optical fiber light guide 8
Light is emitted for a period of 2 μs. When the strobe illumination 7 emits light, the image of the sheet-like material 3 is input from the image input device 4 as a still image. For example, when the traveling speed is 3 m / min, 0.2 is required to move by 10 μm which is the resolution. Therefore, the emission time is 12
Then, it moves only by 0.6 μm. From this image, the number and size of defects are measured by the image processing device 5. The input image at this time, the measured value, and the like are displayed on the display 6.

[0013]

INDUSTRIAL APPLICABILITY The present invention is capable of inspecting a defect of a sheet-like object traveling in a state where the vertical movement range is larger than the depth of focus of the image input apparatus, and is an effect as a sheet-like defect inspection apparatus. Is large.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the apparatus configuration of the present invention.

[Explanation of symbols]

 1, 2 Displacement sensor 3 Sheet material 4 Image input device 5 Image processing device 6 Display 7 Strobe illumination 8 Ring light guide

Claims (2)

[Claims] 1. An image input device for moving a moving sheet-like object up and down within a range larger than a vertical movement range, and a distance between the sheet-like object and the image input device is a focus position ± focus depth. A displacement sensor that outputs an inspection start signal to an image processing device, a strobe lighting device that emits strobe light when the inspection start signal is output, and a reflection illumination that is installed between the image input device and the sheet-like object A defect inspection device for a sheet-like object, comprising a ring-shaped optical fiber light guide and an image processing device. 2. The distance between the sheet and the image input device is
The two series of displacement sensors that output an inspection start signal to the image processing device at the in-focus position ± focal depth and the in-focus position + plate thickness ± focal depth are used. Defect inspection system for sheet materials.