JPH03181807A - Visual apparatus - Google Patents

Abstract

PURPOSE:To improve the checking accuracy by providing a polarizing filter of reach of a projecting system of an illuminating apparatus and a photodetecting system of a camera apparatus, and adjusting the polarizing plane of each polarizing filter so that the regular reflection light at the regular reflection surface is not incident upon the camera apparatus. CONSTITUTION:A polarizing filter is provided in each of a projecting system of an illuminating apparatus 16 and a photodetecting system of a camera device 15. The surface of each polarizing filter is adjusted so that the regular reflection light at the surface of a metallic plate 13 is not incident upon the device 15. The light from the apparatus 16 is, after being polarized by the polarizing filter, irradiated to an object 11 to be checked. This light is regularly reflected at the surface of the metallic plate 13 of the object 11, but refrained from being incident upon the device 16 by the polarizing filter. Moreover, although the light projected to the object 11 is irregularly reflected at the surface of a substrate 12, the polarizing surface is broken, and therefore a part of the light passes through the polarizing filter and enters the device 15. Accordingly, even if the object 11 deforms and the regular reflection surface of the metallic plate 13 is direction in any direction, the light and shade image of the object 11 obtained by the device 15 expresses a dark part of the metallic plate 13 and a bright part of the substrate 12, thus making it possible to easily binarize the light and shade image.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a visual device used in various inspection devices.

<Prior Art> In recent years, a board inspection device has been proposed for automatically inspecting a board on which components are mounted, such as missing components, quality of soldering, quality of component mounting position, etc.

FIG. 4 shows a visual device 1 in this type of substrate inspection apparatus, and a substrate 2 to be inspected, which is an object to be inspected, is located within the visual field of the visual device 1. As shown in FIG.

This visual device 1 is composed of an imaging device 4 having an objective lens 3 attached to its tip, and an illumination device 5 equipped with an annular light source arranged around the outer periphery of the imaging device 4. The imaging device 4 images the substrate 2 to be inspected under illumination and outputs the grayscale image to an image processing bag ff (not shown).

The image processing device binarizes the grayscale image and inspects the component mounting state of the board based on the 200 million images to determine whether it is good or bad.

<Problems to be Solved by the Invention> However, in this type of board inspection, when the surface 8 of the wiring pattern 6 on the surface of the board 2, the electrode part 7 of the mounted component, and the solder is exposed to the light from the illumination device 5, the light is is specularly reflected by these metal surfaces, resulting in high brightness areas. When this high-luminance part is imaged by the imaging device 4, the grayscale image is properly converted into 2
It becomes difficult to convert into a value, reducing inspection accuracy. Furthermore, if the direction of the specular reflection surface is not always constant, the same part may or may not shine with high brightness, which will further reduce the inspection accuracy.

A similar phenomenon occurs not only on metal surfaces but also on mirror surfaces, glass surfaces, glue surfaces, etc. For objects with such specular reflection surfaces, consideration should be given to the positional relationship between the lighting device and the imaging device. This is troublesome for the operator.

In addition, if the target object has specular reflection surfaces in multiple directions, such as a component mounting board, or if the specular reflection surface is not always constant, such as a piece of paper that easily deforms, the position between the devices may vary. Even if the relationship is devised, the effect is poor, and it is difficult to automate testing and improve testing accuracy.

This invention was made with attention to the above problem, and by equipping the projector and the illumination device with polarizing filters, it is possible to automate and inspect any object that has a specular reflection surface. The objective is to provide a new visual device that achieves improved accuracy.

<Means for Solving the Problems> The visual device of the present invention is for observing an object having a specular reflection surface, and is a lighting device for illuminating the object by shining light on the object. , an imaging device for capturing an image of an object under illumination by an illumination device, and polarization filters disposed in the light projection system of the illumination device and the light reception system of the imaging device, and each polarization filter is The polarization plane is adjusted so that the specularly reflected light from the reflective surface does not enter the imaging device.

<Operation> The light from the illumination device is polarized by the polarizing filter and then irradiated onto the object. When this irradiation light hits the specular reflection surface, the reflected light maintains its polarization plane, so the polarization filter prevents the reflected light from entering the imaging device. On the other hand, when the irradiation light hits a portion other than the specular reflection surface, that is, the diffused reflection surface, the polarization plane of the reflected light is distorted, so that the reflected light passes through the polarization filter and enters the imaging device. Therefore, the specular reflection surface always appears as a dark part on the gray scale image, regardless of its orientation, so that the binarization process of the gray scale image becomes easy and stable, and the inspection accuracy improves.

<Example> FIG. 1 shows an inspection device in which a visual device 10 according to the present invention is used.

The inspection object 11 here has a structure in which a band-like metal plate 13 is glued onto a rectangular paper substrate 12, and this inspection device checks whether the metal plate 13 is missing or not. 13 is bonded to the proper position on the substrate 12. In this inspection object 11, the surface of the metal plate 13 is a specular reflection surface, and the surface of the substrate 12 is a diffuse reflection surface.
The direction of the regular reflection surface is not always constant depending on the degree of warpage or deformation of the substrate 12.

In the figure, 14 is a conveyor belt for conveying a plurality of inspection objects 11 one after another to an inspection position, and at the inspection position, an imaging device 15 and an illumination device 16 that constitute the visual device 10 are located above the conveyor belt 14. is provided and electrically connects the vision device 10 to the control device 17.

Lighting bag! 16 illuminates the inspection object 11 with light;
Further, the imaging device 15 images the inspection object 11 under illumination by the illumination device 16 . The control device 17 includes a display section 18,
After the grayscale image obtained by the imaging device 16 is binarized, a predetermined recognition process is performed on the binary image to determine whether the inspection object 11 is good or bad. In addition to executing such image processing, the control device f17 also has a function of controlling the operation of the illumination device 16.The display section 18 displays test results in addition to displaying grayscale images and binary images.

The light projecting system of the illumination device 16 and the light receiving system of the imaging device 15 are each equipped with a polarizing filter.
Each plane of polarization is adjusted so that the light does not enter the beam.

FIG. 2 shows a polarizing filter 20 provided in the light projection system of the illumination device 16 and a polarizing filter 21 provided in the light receiving system of the imaging bag N, 15. The state in which the light passing through the polarizing filter 20 is irradiated onto the point 22 on the specular reflection surface is shown in FIG. shown respectively.

In the illustrated example, the polarizing filter 20 has its polarization plane set in the vertical direction, thereby polarizing the incident light a to obtain a passing longitudinal wave. This passing light is point 2 on the specular reflection surface.
2, the reflected light C maintains its polarization plane (Fig. 2 (1)). However, when the passing light hits point 23 on the diffuse reflection surface, the reflected light d becomes polarized. The surface is in a crooked state (Fig. 2 (2)).

The polarizing filter 21 on the imaging device 15 side has a polarization plane set in the horizontal direction, thereby allowing only incident transverse wave light to pass through. Therefore, the reflected light C at point 22 on the specular reflection surface is blocked by this polarizing filter 21, while a part of the reflected light d at point 23 on the diffused reflection surface passes through this polarizing filter 21.

3(]) to (5) show various aspects of the illumination device 16 in the visual device 10, in which 15 is an imaging device, 16 is an illumination device, and 20 is polarized light on the side of the illumination device 16. A filter 21 is a polarizing filter 1 on the imaging device 15 side.
1 is the object to be inspected.

FIG. 3(1) shows an example of oblique illumination in which the illumination device 16 is arranged so as to illuminate the inspection object 11 from diagonally above.

FIG. 3(2) shows an embodiment of coaxial epi-illumination in which a lighting device 16 and a half mirror 24 are arranged so as to illuminate the inspection object 11 from directly above.

FIG. 3(3) shows an embodiment of ring illumination arranged around the outer periphery of the imaging device 15 using an annular light source as the illumination device 16.

FIG. 3(4) shows an embodiment of indirect transmitted illumination in which an illumination bag 216 is composed of an annular light source 16A and a translucent diffuser plate 16B.

FIG. 3 (5) shows an annular light source 16A and a diffuse reflection plate 16.
This is an example of indirect reflection lighting in which a lighting device 16 is configured with C.

In the inspection apparatus configured as described above, when the inspection object 11 is conveyed to the inspection position by the conveyor belt 14, it is detected by a photoelectric switch (not shown) or the like, and the illumination device 16 and the imaging device 15 are activated. After the light from the illumination device 16 is polarized by a polarizing filter 20, the passing light is irradiated onto the workpiece 1 to be inspected. This light is the metal plate 13 of the inspection object 11.
However, since the specularly reflected light maintains its polarization plane, the polarizing filter 21 prevents the light from entering the imaging device 16 .

On the other hand, the light irradiated onto the inspection object 11 is diffusely reflected on the surface of the substrate 12, but since the plane of polarization of the reflected light is distorted, some of the light passes through the polarizing filter 21 and passes through the imaging device! It will be incident on 15.

For this reason, there is warpage or deformation in the inspection object 11, and the metal plate 1
No matter which direction the specular reflection surface of 3 faces, the imaging device 15
In the grayscale image of the inspection object 11 obtained in , the image of the metal plate 13 always appears as a dark part, and the image of the substrate 12 always appears as a bright part, so that the binarization process of the grayscale image is easy and stable. This improves inspection accuracy.

<Effects of the Invention> As described above, the present invention provides an illumination device for illuminating the object by shining light on the object when observing the object having a regular reflection surface, and an illumination device for illuminating the object by illuminating the object with light. A visual device is constituted by an imaging device for taking an image of Since the specular reflection light is adjusted so that it does not enter the imaging device, the specular reflection surface always appears as a dark part on the grayscale image obtained by the imaging device, regardless of its orientation, so it is necessary to binarize the grayscale image. The invention achieves the purpose of the invention and has remarkable effects, such as easier and more stable inspection and improved inspection accuracy.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the appearance of an inspection device to which the present invention is applied, Fig. 2 is an explanatory diagram showing the arrangement of polarizing filters and the principle of the invention, and Fig. 3 shows various embodiments of the visual device. FIG. 4 is an explanatory diagram showing the appearance of a conventional visual device. 10...Visual device 15...Imaging device 1
6...Lighting device 20, 21...Polarizing filter

Claims (1)

[Claims] A visual device for observing an object having a specular reflection surface, comprising: an illumination device for illuminating the object by illuminating the object; and an illumination device for illuminating the object by illuminating the object. It is composed of an imaging device for capturing an image, and polarizing filters disposed in the light projection system of the illumination device and the light receiving system of the imaging device, and each polarizing filter is configured so that the specularly reflected light from the specular reflection surface is transmitted to the imaging device. A visual device whose plane of polarization is adjusted so that it does not enter the light.