JPH04198743A - 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 secondary differential processing to the digital image data to emphasize the defect, and integrating the concentration values of picture elements in the defect generation 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 secondary differential 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 concentration integration values is obtained, a 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 [Field of Industrial 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 irradiates the surface with He-Ne laser light and utilizes the fact that it 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 complex and the equipment is large-scale.

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

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

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. A surface condition inspection device comprising an output device that outputs a result, the determination device A/D converting a video input signal from an imaging device to create a two-dimensional digital image, and Second-order differential processing is performed on the image data to emphasize defects, and the density value of each pixel is integrated in the direction of defect occurrence to obtain a one-dimensional density integral value signal orthogonal to the direction of defect occurrence. 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. That's how it is.

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

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

This method determines the surface condition by integrating the density of the 0 surface 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, and Fig. 4 is a schematic diagram showing a streak-like defect existing on the surface. The figure is a matrix diagram of the second-order differential, FIG. 5 is a distribution diagram showing the density value signal, and FIG. 6 is a distribution diagram showing the density integral value signal.

The surface condition inspection device 1 includes a television camera 10 (imaging device W).
, a determination device 20 , and an output device 30 , and inspects the surface of an object to be inspected, such as a 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 M20.

(2) The determination device 20 quantizes the image data of the television camera 10 using 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) Based on the image input to the image memory 22, the determination device 20 uses the CPU 23 to determine the presence or absence of a streak-like defect on the surface.

(4) The output device w30 displays the determination result of the determination device 20 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 2o does not necessarily use the image memory 22, and the
The output data of the /D converter 21 may be input directly to the CPU 23.

However, the determination operation by the determination device 20 is as follows.
This is done as follows (see Figure 2).

(2) For example, the operator shown in FIG. 4 is applied to digital image data of MXN pixels to perform second-order differential processing to emphasize defects.

That is, for digital image data of MXN pixels, a product-sum calculation is performed using a spatial filter with weights 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 direction in which the defect occurs (for example, in the 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) Ten...+ f (M, N-1) +
f (M, N) ... (1) ■ Find the average value AVE of the above density integral value S (M).

AVE= (S (1) +S (2)+...
10S (M-1) 10S (M))/M...(2) (2) Determine a threshold value by adding the offset value Z determined in advance to the average density integral value AVE.

■Each concentration integral value (S(I), I:1, 2...M-1
, M) with the threshold value (AVE+Z), it is determined whether the surface condition of the object to be inspected is good or bad, and the result is output.

5(I)>AVE+Z=>Poor (1≦■≦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 the influence of noise is large and it is not possible to determine whether the surface condition is good or bad.

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) 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 a state close to that of the human eye.

The present invention can be widely used not only for surface abnormality inspection but also for grading 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 secondary A differential matrix diagram, FIG. 5 is a distribution diagram showing the density value signal, and FIG. 6 is a distribution diagram showing the density integral value signal. 10... Imaging device, 20... Determination device, 30... Output device. Patent applicant Hiroshi, representative of Sekisui Chemical Co., Ltd. 1) Kaoru Figure 5 M M < a) Non-defective product concentration profile (b) Defective product concentration profile Figure 6

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 second-order differential processing on the digital image data. The density value of each pixel is integrated in the defect generation direction to obtain a one-dimensional density integral signal perpendicular to the defect generation direction, the average of the density integral values is calculated, and the average density integral value is A surface condition inspection device that determines whether the surface condition of an object to be inspected is good or bad by determining a threshold value by adding a certain offset value to the threshold value and comparing each density integral value with the threshold value.