JPH01219505A - Automatic inspecting device for film smoothness - Google Patents

Abstract

PURPOSE:To detect the smoothness of the film automatically and accurately without flawing the film by providing a stripe pattern projecting means, a Fourier transforming means, a filter means, and a smoothness deciding means. CONSTITUTION:The stripe pattern projecting means M1 projects a predetermined basic stripe pattern on a coated body to be inspected. Then the Fourier transforming means M2 processes an image of the stripe pattern projected on the surface of the body to be inspected by the stripe pattern projecting means M1 by Fourier transformation. A filter means M3 removes the component of the image corresponding to the basic stripe pattern projected by the stripe pattern projecting means M1 from the component of the Fourier-transformed image. A smoothness deciding means M4 detects the quantities of light of the images before and after the filter means M3 and decides the smoothness of the film of the body to be inspected according to the detected quantities of light. Thus, the distortion and disorder of the image of the light-shape pattern on the surface of the body to be inspected to decide the film smoothness of the object body without contacting the object body directly.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Field of Industrial Application] The present invention relates to an automatic coating film smoothness inspection device for detecting the smoothness of a coating film.

[Prior Art] Various inventions and proposals have been made to automatically detect the smoothness (yuzu texture) of a coating film. Such inventions and proposals include, for example, ``a light source 50 and a vertical striped grating 51 for measuring the smoothness of a painted surface'' as disclosed in Japanese Patent Application Laid-open No. 18210/1983.
As a result, the painted surface is 52.

A vertical striped pattern is projected, the projected vertical striped pattern is imaged by a COD camera 53, and a microcomputer 54 serving as an image processing device generates an I! The i-imaged and outputted video signal is compared with a predetermined reference value, and the variation in the interval of the vertical striped pattern is calculated from the binary video signal obtained, and the Yuzu texture (painted surface smoothness) is determined. Here, the urethane 55 in the figure is a light-shielding elastic body that prevents light from entering the device from outside.

[Problems to be Solved by the Invention] However, due to the above-mentioned conventional configuration for automatically determining coating film smoothness and moisture content, it is necessary to bring the inspection device close to and in contact with the coating surface 52 as the object to be inspected. Ta. For this reason,
The following issues were considered. That is, (a> assembled, painted or processed on a conveyor,
In other words, the placement position of the product as the object to be inspected on the production line is not fixed at a fixed position, but changes in position. For example, on a car manufacturing line, the positional accuracy of the car body relative to the line (conveyor) is ±1.
An error of about 5 [mm] is generated. Therefore, with conventional inspection equipment, there is a problem that it is not possible to inspect the coating film of products on the production line because it is necessary to make accurate contact. The device is
Although there is no problem in inspecting a paint film that has been baked with a baked finish, it is recommended to inspect objects that have a paint film that has been normally painted, especially a paint film that has not completely dried, due to the risk of damaging the paint film. The problem of not being able to do so was considered.

The automatic coating film smoothness inspection device of the present invention has been developed with the aim of solving the above problems.

The automatic coating film smoothness inspection device of the present invention, as shown in FIG. 1 as an example of its basic configuration, includes a stripe pattern projection means (Ml) that projects a predetermined basic stripe pattern onto a painted object to be inspected; The striped pattern projection means (M
Fourier transform means (M2) for Fourier transforming the striped pattern image projected on the surface of the upper inspection object by l); filter means (M3) for removing image components corresponding to the basic striped pattern; detecting the light amount of the image before and after the filter means (M3), and detecting the above-mentioned object to be inspected based on each detected light amount A smoothness determining means (M4) for determining the smoothness of the coating film.

[Function] The automatic coating film smoothness inspection device of the present invention having the above configuration performs Fourier transformation on the striped pattern image projected on the surface of the object to be inspected by the striped pattern projection means (Ml) using the Fourier transformation means (M2). , the image components corresponding to the basic striped pattern produced by the internal line pattern projection means (Ml) of the Fourier-transformed image components are removed by the filter means (M3), and the light amount of each image before and after the filter means (M3) is The smoothness determination means (M4) operates to determine the coating film smoothness of the object to be inspected based on the following.

Generally, as the smoothness of a coating film deteriorates, the bright and dark striped pattern irradiated to that area becomes distorted and disordered. The automatic coating film smoothness inspection device of the present invention was developed with a focus on this phenomenon, and by detecting the distortion and disturbance of the bright and dark striped image on the surface of the object to be inspected, It works to determine the smoothness of the coating film on the object to be inspected without direct contact.

[Example] Next, a preferred example will be described with reference to the drawings in order to further clarify the structure of the automatic coating film smoothness inspection apparatus of the present invention.

As shown in FIG. 2, the automatic coating film smoothness inspection apparatus of this embodiment mainly includes a stripe pattern projection device 1 as a stripe pattern projection means for projecting a basic stripe pattern onto a painted object to be inspected OB. , a convex lens 2 as a Fourier transform means for Fourier transforming a virtual image of a striped pattern on the object to be inspected OB, and a filter means for removing an image component corresponding to the striped pattern, which is the inner part of the image component Fourier transformed by the convex lens 2. It is composed of a filter plate 3 as a filter plate 3, and an electronic control device 4 as a smoothness determination means for determining the coating film smoothness of the object to be inspected 08 from the light amount of each image before and after the filter plate 3.

The striped pattern projection device 1 is composed of a flat plate 10 having a large number of equally spaced slits and a light emitting light source 12 that emits scattered light through a diffuser plate 11. A basic striped pattern with a predetermined pitch as shown in (in this embodiment, the interval between the bright and dark areas is 1.5 mm) is projected.

A photoelectric element (photosensor) 13 is arranged between the diffuser plate 11 and the flat plate 10 and outputs an electric signal according to the amount of light emitted by the light emitting light source 12.

As shown in FIG. 4, the filter plate 3 is composed of a glass plate that blocks the transmission of light only at its center rectangular portion 3a (hereinafter referred to as a light blocking portion), and the light blocking portion 3a is a glass plate that blocks the transmission of light. The convex lens 2 is located at a distance of 11 focal lengths from the convex lens 2 on the central axis of the convex lens 2 . This filter plate 3
The amount of transmitted light is measured by a photoelectric element 15 via a condensing lens 14.

A half mirror 16 is provided between the convex lens 2 and the filter plate 3.
is arranged, and the amount of light reflected by this half mirror 16 is measured by a photoelectric element 17.

The electronic control device 4 is configured as a logical operation circuit which mainly includes a well-known CPU 4a, ROM 4b, and RAM 4c, and these are interconnected with an external input circuit 4d, an external output circuit 4e, etc. via a bus 4f, and the external input circuit 4d is The photoelectric elements 13, 15, and 17 described above are connected to each other.

Next, the operation of this embodiment having the above configuration will be explained.

A basic striped pattern is projected onto the surface of the object to be inspected by the striped pattern projection device 1, and a virtual image (hereinafter referred to as a striped virtual image) of this basic striped pattern is captured by the convex lens 2.

If the coating film smoothness of the object to be inspected OB is good, the striped virtual image ■i on the surface of the object to be inspected 08 can be perceived as a regular striped pattern that is almost the same as the basic striped pattern (Fig. 5 [A]). . On the other hand, if the coating film smoothness of the object to be inspected OB is poor, the basic striped pattern is distorted and disordered and is perceived as an irregular striped virtual image ■i (FIG. 5 [B]).

The fringe image Vi on the surface of the object to be inspected 08 is captured by the convex lens 2 and then reaches the filter plate 3, but a part of the light is reflected by the half mirror 16 and reaches the photoelectric element 17.

The fringe virtual image Vi reaching the filter plate 3 is Fourier transformed by the convex lens 2. The Fourier transform performed by this convex lens 2 depends on the pitch between the bright and dark parts of the fringe virtual image Vi (hereinafter simply referred to as fringe pitch), that is, the spatial frequency, and when the fringe virtual image Vi is not distorted or disturbed, , striped virtual image Vi
is converted into an image in which several bright points br are lined up horizontally at intervals according to the above-mentioned fringe pitch (FIG. 5 [C]). On the other hand, if the striped virtual image Vi is distorted and disordered, it is converted into an image in which, in addition to several bright points br arranged in a row horizontally, there are many bright points br above, below, to the left, and to the right (Fig. 5 [ D]).

In other words, the disturbance in the spatial frequency of the fringe virtual image (i) generates a large number of bright points br other than the several bright points br in a horizontal row. The frequency of occurrence of bright points br other than the several bright points br in a horizontal row is determined by the degree of distortion disturbance of the striped virtual image Vi, that is,
corresponds to the high frequency component of the spatial frequency.

The Fourier-transformed image reaches the filter plate 3, where several bright spots br in a horizontal row are removed by the light blocking portion 3a of the filter plate 3. In other words, the image component corresponding to the white basic striped pattern of the components of the striped virtual image Vi is removed.

Therefore, when the fringe virtual image vi is not distorted and disturbed, the number of bright points br passing through the filter plate 3 is zero (Fig. 5 [
E]), if the striped virtual image (i) is distorted and disordered, the number (or amount) of bright points br will be passed through depending on the degree of distortion and disorder. (FIG. 5 [F]) The light that passes through the filter plate 3 and is collected by the condenser lens 14 reaches the photoelectric element 15. The photoelectric element 15 sends an electric signal corresponding to the amount of light received to the external input circuit 4 of the electronic control device 4.
Output to d. Similarly, the photoelectric element 17 is a half mirror.
16 outputs an electric signal corresponding to the amount of light reflected by the external input circuit 4d.

The electronic control device 4 performs the following processing.

First, the photoelectric elements 13, 15, and 17 detect the amount of light according to the basic striped pattern produced by the striped pattern projector 1, the amount of light of the image passing through the filter plate 3, and the amount of imaged light reflected by the half mirror 16, respectively. FIG. 6 step 100).

Next, the light reflectance R @ of the object to be inspected is calculated, and the glossiness (gloss 1 PH) of the object to be inspected is determined from this reflectance R (step 110). This process is performed as follows. It is done.

That is, the reflectance R(
-Pi/P2), and calculates the glossiness PH according to the reflectance R calculated from the map for each paint color (graph (1, q2> in Figure 7) stored in the ROM 4b in advance. Here, Graph g1 shows the maps when the paint color is white, and graph g2 shows the maps when the paint color is black.

When the glossiness PH is determined, the light IP3 detected by the photoelectric element 15 and the light amount P1 detected by the photoelectric element 17 are calculated.
The transmission ratio (=P3/Pi) is calculated from the ratio of R
A process for determining the degree of smoothness OP is performed in accordance with the transmission ratio H calculated from the map (FIG. 8) stored in the OM 4b (step 120).

Here, the map shown in FIG. 8 is a map in which the relationship between the smoothness OP of the coating film and the transmittance ratio H is previously investigated and memorized as a sensory value.

When the smoothness OP is determined, the determined glossiness PH and smoothness OP are output as smoothness information in step 130.
), processing can be handled by rRETURNJ.

According to the automatic coating film smoothness inspection apparatus of this embodiment, the coating film smoothness OP of the inspected object OB can be determined by simply irradiating the inspected object OB with a basic striped pattern. As a result, the coating film smoothness of the inspected object OB on the conveyor with poor positional accuracy can be improved.
It has the excellent effect of being able to automatically detect the paint film without damaging it. Furthermore, since the degree of distortion and disturbance of the striped virtual image (i) on the object to be inspected OB is detected from the amount of light transmitted through the filter plate 3 using the convex lens 2 that Fourier transforms the light and the filter plate 3, It has the excellent effect of being able to accurately determine the coating film smoothness OP. Furthermore, since the smoothness OP is calculated from the ratio of the amount of light before and after the filter plate 3, the smoothness can be determined more accurately without being affected by differences in the paint color of the object to be inspected. be effective. Moreover, this embodiment has an excellent effect in that the glossiness PH of the object to be inspected OB is also neutralized, which can be used to judge the condition of the coating.

In this embodiment, the light intensity of the bright point br passing through the filter plate 3 is directly detected, but the filter plate 3
The image of the bright point br passing through may be further subjected to inverse Fourier transform, and the smoothness OP may be determined based on this inverse Fourier transform image. In this case, when the striped virtual image (i) is irregular, the image after inverse Fourier transformation becomes a bright part distorted and disordered by the coating film, that is, an image in which light points (bright spots) are scattered.

Next, an automatic coating film smoothness inspection apparatus according to a second embodiment of the present invention will be explained. Although not shown in the drawings, the automatic coating film smoothness inspection apparatus of the second embodiment images the striped virtual image Vi on the object to be inspected OB shown in FIG. It processes images. This image processing is performed according to the "smoothness determination processing routine" shown in FIG.

This image processing will be explained below.

When determining the smoothness of the coating film of the object to be inspected OB (steps 200 and 210>, the level of the captured video signal is set within a predetermined range and step 220), this corrected video signal is used as described in the first embodiment. Fourier transform is performed in the same way as the effect of convex lens 2 (step 230). Next, in the same way as the action of the filter plate 3, a logical AND with the mask pattern is taken (step 240).
0).

As a result, only the distorted and disordered striped pattern signal is extracted. After this, the inverse Fourier transformed signal is converted to a predetermined base t1! The area of the bright area is calculated from the signal that becomes the bright area (step 270).
The smoothness of the coating film is calculated from the calculated area and output to the outside (steps 280 and 290). On the other hand, when obtaining the glossiness of the paint film (step 210), the brightness of the striped pattern is converted into a histogram from the input video signal (step 300), and the width of the brightness distribution obtained (step 310) is shown in FIG. The glossiness is calculated from the map shown in and output to the outside (steps 320 and 330>).

The automatic coating film smoothness inspection device of the second embodiment has the same effects as the first embodiment, and since the striped virtual image on the object to be inspected OB is directly captured by a TV camera, it is not affected by external light. This has the effect of reducing the amount of

Although the embodiments of the present invention have been described in detail above, the automatic coating film smoothness inspection device of the present invention is not limited to the above embodiments, and can be modified in various ways without departing from the gist of the present invention. It is possible to implement. For example, it is conceivable to arrange the convex lens 2° filter plate 3, photoelectric element 15, etc. in the first embodiment in a dark box. Even in this case, there is no need to directly contact the object to be inspected OB unlike in the conventional case.

Effects of the Invention According to the automatic paint film smoothness inspection device of the present invention, the paint film smoothness of an object to be inspected on a conveyor with poor positional accuracy can be automatically and accurately detected without damaging the paint film. It has this excellent effect.

In addition, since the smoothness of the coating film is determined based on the amount of light of the image in front of the filter means, the smoothness can be determined more accurately without being affected by differences in the coating color of the object to be inspected. has.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an automatic coating film smoothness inspection device of the present invention, Fig. 2 is an overall schematic diagram showing an automatic coating film smoothness inspection device which is an embodiment of the present invention, and Fig. 3 is a block diagram showing the configuration of an automatic coating film smoothness inspection device of the present invention. Explanatory diagram showing the basic striped pattern projected by the striped pattern projection device, No. 4
The figure is a front view showing the filter plate 3, and FIGS.
F] is an explanatory diagram showing how the striped virtual image Vi changes, FIG. 6 is a flowchart showing the processing of the "smoothness information calculation processing routine", and FIG. 7 is a map showing the relationship between reflectance R and glossiness PH. , FIG. 8 is a map showing the relationship between transmittance ratio H and smoothness OP, FIG. 9 is a flowchart showing the process of the "smoothness determination processing routine" used in the second embodiment, and FIG.
The figure is a schematic diagram showing an example of a conventional inspection device. Ml... Striped pattern projection means M2... Fourier transform M
3... Filter means M4... Smoothness determination means 1
... Striped pattern projection device 2 ... Convex lens 3 ... Filter plate 4 ... Electronic control device 13,15.17.
...Photoelectric element 08...Inspection object representative Patent attorney Tsutomu Sadatsu (and 2 others) Figure 1 Figure 3 Figure 5 [A] [E] r [Snake] [0]
[F]Dr.
Dr Figure 6 Figure 7 Glossiness PH Figure 8 ↑ Smoothness OP 10'J

Claims (1)

[Scope of Claims] Striped pattern projection means for projecting a predetermined basic striped pattern onto a painted object to be inspected; Fourier transform means for converting; filter means for removing image components corresponding to the basic striped pattern projected by the stripe pattern projection means from among the components of the Fourier transformed image; and images before and after the filter means. Detect the amount of light of each,
An automatic coating film smoothness inspection device comprising: smoothness determining means for determining the coating smoothness of the object to be inspected based on each of the detected amounts of light.