JPH04198744A - Surface state inspecting device - Google Patents

Abstract

PURPOSE:To surely detect a stripe-shaped defect in the state similar to a human eye by applying the concentration gradient processing to the digital image data to emphasize the defect, and integrating the concentration values of picture elements in the defect occurrence direction to detect the surface state. CONSTITUTION:The surface of a film 11 is photographed with a television camera 10, the photographed data are A/D-converted 21 to form a digital image, and it is inputted to an image memory 22. A CPU 23 applies the concentration gradient processing to the image inputted to the image memory 22 to emphasize a defect, the concentration values of picture elements are integrated in the defect occurrence direction to erase the effect of noises such as illumination irregularities, the one- dimensional concentration integration value signal perpendicular to the defect occurrence direction is formed, the average of the concentration integration values is obtained, the threshold value added with a fixed offset value to the average concentration integration value is obtained, each concentration integration value is compared with the threshold value to judge the presence of a stripe-shaped defect on the surface, and the judged result is displayed on an output device 30. A device can be made compact, and the surface state such as the stripe-shaped defect can be surely detected in the state similar to a human eye.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a surface condition inspection device suitable for inspecting streak-like defects etc. existing on the surface of a film or the like.

[Prior Art] As an apparatus for inspecting abnormalities existing on the surface of a film or the like, there is one that utilizes the fact that the surface is irradiated with He-Ne laser light and the light is scattered in arbitrary directions by dust or the like.

[Problems to be Solved by the Invention] However, the prior art has the following problems (1) to (3).

■The optical system is complicated and the equipment is large-scale.

■Poor detection ability for streak-like defects flowing in the line direction.

■Detection results do not necessarily match the sense perceived by the human eye.

An object of the present invention is to use a compact device configuration to reliably detect surface conditions such as streak-like defects in conditions similar to those seen by the human eye.

[Means for Solving the Problems] The present invention provides an imaging device that images the surface of an object to be inspected, a determination device that determines the surface state of the object to be inspected based on the imaging result of the imaging device, and a determination method of the determination device. The surface condition inspection device is configured to include an output device that outputs a result, and the determination device A/D converts the video input signal from the imaging device to create a two-dimensional digital image, and the determination device generates a two-dimensional digital image. The image data is subjected to density gradient processing to emphasize defects, and the density value of each pixel is integrated in the direction of defect occurrence to produce a one-dimensional density integral value signal orthogonal to the direction of defect occurrence. The average is determined, a threshold value is determined by adding a certain offset value to the average integrated density value, and each integrated density value is compared with the threshold value to determine whether the surface condition of the object to be inspected is good or bad. This is what I did.

[Effect] According to the present invention, the following effects (1) to (4) are achieved.

■The surface condition can be detected using a versatile imaging device such as a television camera, making the device configuration compact.

(2) The surface condition is determined by integrating the surface concentration in the direction of defect occurrence, which can eliminate the effects of noise such as uneven illumination, and can reliably detect surface conditions such as streak-like defects.

■Since the surface condition is detected based on the surface concentration, the surface condition can be detected in conditions similar to those seen by the human eye.

[Example] Fig. 1 is a block diagram showing an example of the inspection apparatus of the present invention, Fig. 2 is a flow chart showing the inspection procedure, Fig. 3 is a schematic diagram showing a streak-like defect existing on the surface, Fig. 4 This figure is a matrix diagram of concentration gradients, FIG. 5 is a distribution diagram showing density value signals, and FIG. 6 is a distribution diagram showing density integral value signals.

The surface condition inspection device 1 includes a television camera 10 (imaging device)
It has a determination device 20, and an output device 3o, and inspects the surface of the object to be inspected, such as the film 11, for abnormalities.

The basic operations of the surface condition inspection device 1 are as follows (1) to (4)
It is.

(1) The surface of the film 11 is imaged by the television camera 10.

The television camera 10 transfers a multivalued image sampled pixel by pixel to the determination device 20.

(2) The determination device 20 quantizes the image data of the television camera 1o with an A/D converter 21, for example, at 8 bits (256 gradations), creates a digital image of MXN pixels, and inputs this into the image memory 22. do.

(3) The determining device 20 uses the CPU 23 to determine the presence or absence of a streak-like defect on the surface based on the image input to the image memory 22.

(4) The output device 30 displays the determination result of the determination device 2o and generates an alarm if necessary.

Note that as the imaging device (10), a line sensor having M spatial resolution may be used instead of the television camera. In this case, the line sensor and the object to be inspected are moved relative to each other, Store the data of the N side group in the image memory.

The determination device 20 does not necessarily use the image memory 22;
The output data of the /D converter 21 may be input directly to the CPU 23.

However, the determination operation by the determination device 220 is as follows.
This is done as follows (see Figure 2).

(2) For example, an operator shown in FIG. 4 is applied to digital image data of MXN pixels to perform density gradient processing to emphasize defects.

That is, for digital image data of MXN pixels, for example, a weighted spatial filter as shown in FIG. Emphasize.

■In order to eliminate the influence of noise such as uneven illumination, the density value of each pixel is integrated in the defect occurrence direction (for example, N direction) (f
(M, N) is the density value of each pixel), thereby obtaining a one-dimensional density integral value signal orthogonal to the direction of defect occurrence.

S (M) = f (M, 1) + f (M,
2) +−−−−−−+ f (M, N−1) +
f (M, N) ... (1) ■ Find the average value AVE of the above density integral value S (M).

A V E = (S (1) + S (2)
+,,,,,.

+ S (M-1) + S (M-1) + S (
Ml)/M...(2) (2) Determine a threshold value by adding the offset value 2 determined in advance to the average density integral value AVE.

■Each concentration integral value (S(I)), r: 1.2,...
- Compare M-1, M) with the above threshold value (AVE+Z), determine whether the surface condition of the object to be inspected is good or bad, and output the result.

5 (I) > AVE + Z bar defect (1 ≦ engineering ≦ M) ... (3) Figure 5 shows M when the density value of each pixel is not integrated.
This is a concentration profile along a directional line. It is recognized that it is not possible to determine whether the surface condition is good or bad, probably due to the influence of noise.

FIG. 6 shows how the surface condition inspection device 1 of the present invention is used to determine whether the surface condition of the object to be inspected is good or bad. By integrating the density value of each pixel, it is possible to reliably determine whether the surface condition is good or bad. It is recognized that it can be distinguished.

According to the above embodiment, the following effects (1) to (4) are achieved.

- Surface conditions can be detected using a versatile imaging device such as the television camera 10, and the device configuration can be made compact.

(2) There is a device that determines the surface condition by integrating the surface concentration in the direction of defect occurrence, which can eliminate the effects of noise such as uneven illumination, and can reliably detect surface conditions such as streak-like defects.

■Since the surface condition is detected based on the surface concentration, the surface condition can be detected in conditions similar to those seen by the human eye.

Note that the present invention can be widely used not only for inspecting surface abnormalities but also for classifying surface conditions.

[Effects of the Invention] As described above, according to the present invention, surface conditions such as streak-like defects can be reliably detected in a state similar to that seen by the human eye, using a compact device configuration.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of the inspection device of the present invention, Fig. 2 is a flowchart showing the inspection procedure, Fig. 3 is a schematic diagram showing streak-like defects existing on the surface, and Fig. 4 is a concentration gradient. FIG. 5 is a distribution diagram showing density value signals, and FIG. 6 is a distribution diagram showing density integral value signals. 10... Imaging device, 20-... Determination device, 30... Output device. Patent applicant: Sekisui Chemical Co., Ltd. Representative Hiroshi 1) Kaoru Figure 1 Film Figure 3 Figure 4

Claims (1)

[Claims] (1) It has an imaging device that images the surface of the object to be inspected, a determination device that determines the surface state of the object to be inspected based on the imaging result of the imaging device, and an output device that outputs the determination result of the determination device. The determination device A/D converts a video input signal from an imaging device to create a two-dimensional digital image, and performs density gradient processing on the digital image data. to emphasize the defect, integrate the density value of each pixel in the direction of defect occurrence, obtain a one-dimensional density integral value signal perpendicular to the direction of defect occurrence, calculate the average of the density integral values, and calculate the average density integral value. A surface condition inspection apparatus that determines whether a surface condition of an object to be inspected is good or bad by determining a threshold value to which a certain offset value is added and comparing each density integral value with the threshold value.