JPH0269641A - Device for incorporating reflected light of object to be measured - Google Patents

Abstract

PURPOSE:To obtain stable contrast without depending on the state of a metallic surface by respectively providing polarizing plates on an optical system which makes an object to be measured irradiated with illuminating light and an optical system which conducts reflected light from the object to be measured to a monitoring part. CONSTITUTION:Light from a light source 11 is condensed by a lens 14 through a 1st polarizing plate 12 and an infrared-ray cut filter 13 and reflected by a half mirror 15 so as to irradiate the object to be measured. The reflected light from the object to be measured 30 is condensed by a lens 16 through the mirror 15 and conducted to a CCD camera part 18 through a 2nd polarizing plate 17. By rotating the polarizing plate 12 or 17 in such a constitution, the polarized surface of the reflected light from the metallic part 3A changes and all the reflected light from the metallic part 3A is cut at a certain angle by the polarizing plate 17. On the other hand, the reflected light from the non-metallic part is scattered and polarization can not be maintained. Then, the light is reflected to the camera part 18 with sufficient light quantity. Therefore, a contrasty video with light and darkness between the metallic part and the non-metallic part can be obtained as an image pickup part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a device for capturing reflected light from a δFl object, which is used, for example, in an inspection apparatus for inspecting chip components on a substrate.

(Prior Art) A device has been developed that automatically inspects whether chip components mounted on a printed wiring board are accurately mounted in a normal position. This device illuminates the printed wiring board, guides the reflected light to an imaging section, and performs inspection using image processing technology.

What is important here is that the position of the chip component be recognized with high precision, and for this purpose clear contrast is required when it is imaged.

For this reason, conventional inspection equipment uses halogen lamps, strobes, etc., and guides the light to the object to be measured through a fiber or the like to obtain a sufficient amount of light to provide contrast.

(Problems to be Solved by the Invention) As mentioned above, in the conventional apparatus, since it was attempted to obtain an image with good contrast using general light, especially when imaging a mirror surface such as a metal surface, the condition of the metal surface may be affected. There is a phenomenon in which the contrast of an image changes drastically. Automatic inspection equipment uses a method of capturing reflected light with a CCD imaging camera and binarizing the output signal for pattern recognition, but as mentioned above, if the contrast changes drastically depending on the condition of the metal surface, Accurate binarized images cannot be obtained.

For example, if the object to be measured is a perfect mirror surface, when viewed from the camera, it will be bright if the illumination light is reflected on this mirror surface, and dark if it is not. However, if the metal surface has a curvature or has many scratches, etc. Diffuse reflection creates a mix of brightness and darkness, which affects the brightness of the metal surface.

Especially when there is solder on the surface of printed circuit boards, etc.
This tendency was severe, and there were many malfunctions of inspection equipment.

SUMMARY OF THE INVENTION An object of the present invention is to provide a device for capturing reflected light of an object to be measured, which is capable of obtaining stable contrast regardless of the state of the metal surface and is useful for obtaining accurate images.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a first optical system that irradiates illumination light from a light source onto an object to be measured via an infrared cut filter and a first polarizing plate; a second optical system that guides the reflected light from the object 71111 to the monitoring unit via a second polarizing plate, and identifies areas of parts of the object 71111 having different light reflection characteristics. It is configured so that it can be done.

(Function) By the above means, the light reflected from the metal part of the object to be measured maintains its polarization property, and the light reflected from the non-metal part does not maintain its polarization property, so that the first and second polarizing plates are Therefore, it is possible to cut the reflected light from metal parts. Therefore, a clear contrast can be obtained as a monitoring section.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. Light from a light source (for example, a lamp) 11 passes through a first polarizing plate 12 and an infrared cut filter 13, is focused by a lens 14, and is reflected by a half mirror 15. This reflected light is irradiated onto the fixed object 30 to be 1j.

The reflected light from the object to be measured 30 passes through the half mirror 15, is focused by the lens 16, and is guided to, for example, a CCDC mechanism 198 as a monitoring section via the second polarizing plate 17.

The object to be measured 30 is, for example, a chip component mounted on a printed circuit board, and the terminal parts 3A and 3B at both ends are metal parts, and the surface between the terminals is made non-metallic by applying an insulating agent or the like. Terminal parts 3A and 3B, which are metal parts, are fixed to the pattern wiring by soldering.

One embodiment of the present invention is configured as described above.

When performing an inspection, the position is set so that the object to be measured 30 is sufficiently irradiated with light from the light source 11. At this point, even if the subject is in focus, it is unclear whether sufficient contrast will be obtained. Next, the polarizing plate 12
Or, as the plate 17 is rotated, the polarization plane of the reflected light from the metal part 3A changes, and at a certain angle, the polarizing plate 17 on the camera side changes.
As a result, all reflected light from the metal portion 3A is cut off. This is because the light reflected by the metal maintains polarization.

In contrast, light reflected by non-metals is scattered and does not maintain polarization. For this reason, the light is not significantly affected by the polarizing plate and is reflected to the camera section with a sufficient amount of light. Therefore, the imaging unit can obtain an image with clear contrast between metal parts and non-metal parts. For example, as you adjust the polarizing plate, as shown in Figure 2, you can change from a blurry image (Figure 2(a)) to an image where metal parts (black) and non-metallic parts can be clearly distinguished (Figure 2(a)). Figure (b)) can be obtained. Thereby, it is possible to obtain a signal exhibiting sufficient contrast to obtain a binarized signal using image processing technology.

Note that the infrared cut filter 13 is for cutting infrared rays that are not polarized even by the polarizing plate.

Furthermore, if the optical characteristics of the image pickup device on the camera side are up to visible light, there is no particular need to attach it.

In the above embodiment, a half mirror is used to show a device in which the paths of the irradiated light and the reflected light on the object to be measured partially follow the same path. Of course, it can be applied to devices. Furthermore, various modifications can be made to the lens configuration, filter configuration, and illumination device configuration.

[Effects of the Invention] As explained above, according to the present invention, stable contrast can be obtained regardless of the condition of the metal surface, and the reflected light of the object to be measured can be captured to obtain accurate images. equipment can be provided.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an example of an image according to the present invention. 11... Light source, 12.17... Polarizing plate, 13...
Infrared cut filter, 14.16... Lens, 15
...Half mirror-18...CCD camera section, 30.
...Object to be measured. Applicant's agent Patent attorney Takehiko Suzue No. 1 (a) (b) Figure 2

Claims (1)

[Scope of Claims] A first optical system that irradiates an object to be measured with illumination light from a light source through an infrared cut filter and a first polarizing plate; and a second polarized light that reflects light from the object to be measured. and a second optical system that leads to the monitoring section through a plate, and is configured to identify regions of parts of the object to be measured having different light reflection characteristics. Capturing device.