JP2003107006A - Lighting method and lighting device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an illumination method used for performing an appearance inspection of an object to be measured such as an electronic component, which eliminates a difference in illuminance between an outer edge portion and a central portion of the object to be measured. An illumination method capable of providing substantially uniform illumination over the entire inspection surface of a device under test. SOLUTION: The illumination method is such that a ring-shaped light beam (12) emitted from a ring-shaped light source is incident on a hollow body (3) having an outer peripheral incident surface (3a) and an inner peripheral exit surface (3b). And irradiates the object to be illuminated from above the object at a stationary position (C) provided substantially on the axis of the hollow body and below the hollow body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating method and an illuminating device, for example, an illuminating method and an illuminating device suitable for irradiating an electronic component when inspecting an electronic component for defects.

[0002]

2. Description of the Related Art As a conventional lighting device used for inspecting electronic parts, there is one shown in a side view in FIGS. In the illumination device of FIG. 4, the light rays emitted from the two light guides 20 are applied to the electronic component 21 on the substrate 23, and the CCD camera 22 captures the image data of the electronic component 21. On the other hand, in the lighting device of FIG.
A light beam emitted from the device is transmitted through the light diffusion plate 25 and applied to the electronic component 21 on the substrate 23, and the CCD camera 22 captures image data of the electronic component 21.

[0003]

In the lighting device shown in FIG. 4, two light guides 20 are arranged on both sides of the electronic component 21, and the electronic component 21 is irradiated obliquely from above. In this illuminating device, since the illuminance is higher as it is closer to the light guide 20, there is a problem in that there is a difference in illuminance between the outer edge portion and the central portion of the electronic component 21, and the shadow of the uneven portion of the electronic component 21 extends in one direction. there were.

In the illuminating device shown in FIG. 5, light is diffused by the light diffusing plate 25, but since a ring-shaped bright and dark portion appears, a difference in illuminance occurs between the outer edge portion and the central portion of the electronic component 21. There was a problem. When such a difference in illuminance occurs, even a normal electronic component may be determined as a defective product.

The present invention has been made in view of the above,
The purpose is to provide a lighting method and a lighting device used for visual inspection of an object to be measured such as an electronic component, which eliminates the difference in illuminance between the outer edge portion and the central portion of the object to be measured. An object of the present invention is to provide an illuminating method and an illuminating device capable of performing substantially uniform illumination over the entire inspection surface of an object to be measured.

[0006]

The present invention has the following structure in order to solve the above problems. The gist of the invention according to claim 1 is to guide a ring-shaped light beam emitted from a ring-shaped light source to the incident surface of a hollow body having an incident surface on the outer periphery and an emission surface on the inner periphery to pass through the hollow body, An illumination method is characterized by irradiating an object to be irradiated, which is located on a substantially central axis of the hollow body and outside the hollow body, in a stationary position. The gist of the invention according to claim 2 is a ring-shaped light source and a light diffusing means for transmitting and diffusing a ring-shaped light beam emitted from the ring-shaped light source, and irradiating the irradiation target object so as to surround a fixed place. A lighting device, comprising: a light diffusing means; and a reflecting means which is arranged so as to surround the light diffusing means and which reflects the ring-shaped light beam and guides it to the light diffusing means. The gist of the invention according to claim 3 is characterized in that the light diffusing means comprises a hollow body having an outer peripheral incident surface and an inner peripheral emitting surface having a shape different from the shape of the incident surface. The lighting device according to claim 2. The gist of the invention according to claim 4 is that the light diffusing means comprises a hollow body having an outer peripheral entrance surface and an inner exit surface, and the shapes of the entrance surface and the exit surface are:
The illumination device according to claim 2 or 3, wherein light rays emitted from the emission surface are determined based on refraction of light so as to reach the irradiation target substantially uniformly. . The gist of the invention according to claim 5 is that the incident surface of the light diffusing means has a conical shape or a truncated cone shape, and the exit surface of the light diffusing means has a spherical surface and a cylindrical surface continuous with the spherical surface. It exists in the illuminating device of Claim 3 or 4 characterized by the above-mentioned. The gist of the invention according to claim 6 is:
The incident surface of the light diffusing means has a shape having a spherical surface and a cylindrical surface continuous with this spherical surface, and the emitting surface of the light diffusing means is continuous with a spherical surface having a curvature different from that of the incident surface. The illumination device according to claim 3 or 4, wherein the illumination device has a shape having a cylindrical surface. The gist of the invention according to claim 7 resides in the illuminating device according to any one of claims 2 to 6, characterized in that the light diffusing means is made of translucent milky white resin. The gist of the invention according to claim 8 is that the light diffusing means is made of glass subjected to a light diffusing process.
The lighting device according to any one of 1 to 6 above. The gist of the invention according to claim 9 is that the reflecting means has a cylinder surrounding the light diffusing means, and the inner surface of the cylinder is formed into a mirror surface. The illuminating device according to claim 1. The gist of the invention according to claim 10 resides in the illumination device according to any one of claims 2 to 9, characterized in that the ring-shaped light source is an optical fiber arranged in a ring shape.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The illumination method according to the present invention uniformly irradiates illumination light from the periphery of an object to be illuminated, and the object to be illuminated is irradiated from directly above, below, directly beside, or in any other direction. Is an illumination method used when observing, measuring, and performing other inspections. This illumination method is shown in FIGS.
2 and FIG. 2 showing refraction of light, the ring-shaped light beam 12 emitted from the ring-shaped light source 5a and passing through the air 12
Having an outer incident surface 3a and an inner exit surface 3b,
The hollow body 3 is guided by the entrance surface 3a of the hollow body 3 having a circular cross section to allow the hollow body 3 to pass therethrough. After that, the diffused light rays that emerge from the emission surface 3b and pass through the air are uniformly irradiated from the surroundings so as to surround the irradiation target object, for example, the irradiation target object at the stationary position C used for measurement. To do. Stationary location C
Are provided on the substantial axis of the hollow body 3 and outside the hollow body 3. The irradiation target at the stationary portion C is observed, measured, and inspected through the hole 3d of the hollow body 3.

The ring-shaped light beam 12 passing through the air is refracted when it enters the hollow body 3, and is further refracted when it leaves the hollow body 3 in the air, that is, when it exits. Therefore,
If the shape, thickness, material, etc. of the hollow body 3 are selected so that the refracted light beam reaches the stationary part C, the ring-shaped light beam 12 reaches the stationary part C substantially uniformly in a diffused state.

The light diffusing plate 25 shown in FIG. 5 is a flat plate,
It is located above the electronic component 21. On the other hand, the light source is the ring light 24, and is arranged so as to irradiate the irradiation target from above the outer periphery of the irradiation target. However, since the irradiation light to the light diffusion plate 25 is the light of the ring light 24 itself and is not made uniform, the ring-shaped bright and dark cannot be completely removed. On the other hand, in the lighting method according to the present invention,
Since the ring-shaped light beam 12 is uniformly emitted from the periphery of the hollow body 3 having the diffusion function to the lower side of the hollow body 3 in the figure, the diffused light beam is located at the stationary portion C provided below the hollow body 3. The object to be irradiated can be uniformly irradiated.

The illumination device 1 according to the present invention allows the ring-shaped light source 5a and the ring-shaped light beam 12 emitted from the ring-shaped light source 5a to be transmitted and diffused so as to surround the stationary portion C of the irradiation target object. The light diffusing means 3 for uniformly irradiating the illuminated object, and the reflecting means 4 arranged around the light diffusing means 3 for reflecting the ring-shaped light beam 12 and guiding it to the light diffusing means 3.
With. In FIG. 3, the ring-shaped light beam 12 is shown as radiation from a single point because it exhibits catadioptric refraction, but in reality, the ring-shaped light source 5 having a thickness h surrounding the light diffusing means 3 is shown.
It is radiated from the entire surface of the end surface 5b of a.

In the illustrated embodiment, the ring-shaped light source 5a
Is manufactured by arranging the optical fiber bundles 5 into individual fibers or separating a plurality of fibers into a ring and uniformly arranging them. The optical fiber bundle 5 is protected by a flexible tube 6, and one end of the optical fiber bundle 5 is guided into the frame 2 and separated into fibers in the frame 2. When the other end of the optical fiber bundle 5 is illuminated with a light source such as a light bulb, a ring-shaped light beam 12 is emitted.

The light diffusing means 3 has an outer incidence surface 3a and an inner emission surface 3 having a shape different from the shape of the incidence surface 3a.
It consists of a hollow body with b. The hollow body 3 is a so-called rotating body obtained by rotating a template having a constant shape around an axis line spaced from a piece of the template. In the embodiment shown in FIG. 1, the cylindrical body 3c is connected to the light diffusing means 3 and extends upward. Cylindrical body 3
The hole 3d of c is used for observation, measurement and other inspections with a CCD camera (not shown).

The shapes of the entrance surface 3a and the exit surface 3b of the hollow body 3 are determined based on the refraction of light so that the diffused light rays emitted from the exit surface 3b reach the object to be illuminated substantially uniformly. To be done.

As shown in FIG. 2, the ring-shaped light beam 12 that has passed through the air (in the description with reference to FIG.
Say. ) Is irradiated to the incident surface 13 of the transparent or semitransparent plate material 11, the light ray 12 is refracted at the incident surface 13 and
It becomes a and advances inside the plate member 11. If the angle between the normal 15 of the incident surface 13 and the light beam 12, that is, the incident angle is θ1, and the angle between the normal line 15 and the refracted light beam 12a, that is, the refraction angle is θ2, then n = (sin θ1 / sin θ
2) is defined as the refractive index. Further, the angle formed by the light ray 12a traveling inside the plate member 11 and the normal line 16 of the emission surface 14 is θ4, and the light ray 12 emitted from the emission surface 14 into the air.
The angle between b and the normal 16 is θ3, and n ′ = (sin θ
3 / sin θ4), the relationship of n = n ′ is established. Therefore, if the entrance surface 13 and the exit surface 14 of the plate material 11 are parallel, the light beam 12b that passes through the plate material 11 and goes out into the air again is a parallel light beam whose optical axis is deviated from the incident light beam 12, If the entrance surface 13 and the exit surface 14 are non-parallel, the light ray 12b is a non-parallel light ray whose optical axis is deviated from the light ray 12. Based on this, the light rays 12b at various points on the hollow body 3 are placed on the substantial center axis of the hollow body 3 and outside the hollow body 3 at a fixed location C (a fixed location provided below in the figure). The shapes of the entrance surface 3a and the exit surface 3b of the hollow body 3 are determined so that C) is uniformly irradiated from the surroundings.

In the embodiment shown in FIGS. 1 and 3, the entrance surface 3a of the hollow body 3 which is the light diffusing means has a conical or truncated cone shape, and the exit surface 3b of the hollow body 3 is a spherical surface having a center O. And a cylindrical surface continuous with this spherical surface. As described above, by making the shapes of the entrance surface 3a and the exit surface 3b different from each other, the normals thereof are non-parallel except for a part, and by providing the exit surface 3b with a spherical surface,
Since the normal lines 10 on the spherical surface are also non-parallel to each other, the ring-shaped light beam 12 passes through the hollow body 3 and is diffused substantially uniformly.

The hollow body 3, which is the light diffusing means, can be made of a translucent milky white resin or light-diffused glass. If the hollow body 3 is made of such a material, the hollow body 3
Diffuse reflection of the ring-shaped light beam 12 that passes through is likely to occur, and diffusion is easily uniformized.

The reflecting means 4 has a cylindrical shape and has a cylindrical inner surface 4a surrounding the hollow body 3 which is the light diffusing means, and the inner surface 4a is formed into a mirror surface.

Of the ring-shaped light beam 12 emitted from the ring-shaped light source 5a, a light beam which does not directly enter the light diffusing means 3,
If the light rays reflected by the light diffusing means 3 escape as they are, the illumination efficiency will decrease. Therefore, by reflecting such a light ray by the reflecting means 4 and guiding it to the light diffusing means 3, the illumination efficiency can be improved.

Instead of the above embodiment, the following implementations are possible. That is, the entrance surface 3a of the hollow body 3 which is the light diffusing means has a shape having a spherical surface and a cylindrical surface continuous with this spherical surface, and the exit surface 3b is connected with a spherical surface having a different curvature from that of the incident surface 3a and this spherical surface. It is possible to have a shape having a cylindrical surface, the incident surface 3a to have a spherical surface and a cylindrical surface connected to this spherical surface, and the output surface 3b to have a conical shape or a truncated cone shape. In short, for the entrance surface 3a and the exit surface 3b of the hollow body which is the light diffusing means, the shape of the exit surface 3b is selected according to the shape of the entrance surface 3a so that the ring-shaped light beam 12 is eventually diffused uniformly. Can be made.

As the material of the hollow body 3, a translucent milky-white resin material which easily causes diffuse reflection, or a material such as frosted glass or white glass having a diffusion effect, which can diffuse and transmit light, is selected. be able to.

[0021]

According to the present invention, since the ring-shaped light beam is refracted and diffused by the light diffusing means, substantially uniform irradiation can be obtained. In addition, by selecting the material of the light diffusing means, the irradiation can be made more uniform. Further, according to the illuminating device of the present invention, the light rays that cannot be directly incident on the light diffusing means are reflected by the reflecting means and guided to the light diffusing means, so that the illumination efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a side view, partly in section, showing an illumination device according to the present invention.

FIG. 2 is a schematic diagram showing refraction of light.

FIG. 3 is a schematic sectional view showing a state in which a ring-shaped light beam is diffused while being refracted by a light diffusing means, and the ring-shaped light beam is shown on only one side.

FIG. 4 is a front view schematically showing a conventional lighting device.

FIG. 5 is a front view showing an outline of another conventional lighting device.

[Explanation of symbols]

1 Lighting device 2 frames 3 Light diffusion means (hollow body) 3a entrance surface 3b exit surface 3c cylindrical body 3d hole 4 reflection means 4a inner surface 5 Optical fiber bundle 5a Ring light source 5b end face 6 Flexible tube 10, 15, 16 normals 11 plate materials 12 Ring light 12a, 12b rays 13 Incident surface 14 Exit surface 20 Light guide 21 electronic components 22 CCD camera 23 board 24 ring light 25 light diffuser C Stationary location O center

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masayoshi Yamada             Forest Watchmaker 1-28-3 Kitaotsuka, Toshima-ku, Tokyo             Business F-term (reference) 2G051 AA61 AA65 AB02 AB14 BA01                       BA02 BB02 BB17 CA03 CA04                       CA11                 2H038 AA54 BA01

Claims (10)

[Claims] 1. A ring-shaped light beam emitted from a ring-shaped light source is guided to the incident surface of a hollow body having an incident surface on the outer periphery and an emission surface on the inner periphery to be transmitted through the hollow body, and the hollow body is substantially formed. Illuminating method, which comprises irradiating an object to be irradiated, which is located at a stationary position provided on the central axis of the hollow body and outside the hollow body. 2. A ring-shaped light source, and a light diffusing means for transmitting and diffusing a ring-shaped light beam emitted from the ring-shaped light source, the light diffusing means for irradiating the irradiation target object so as to surround a fixed portion. An illuminating device, comprising: a reflection means that is arranged so as to surround the light diffusing means and that reflects the ring-shaped light beam and guides it to the light diffusing means. 3. The light diffusion means comprises a hollow body having an incident surface on the outer periphery and an emission surface on the inner periphery having a shape different from the shape of the incident surface. Illumination device described. 4. The light diffusing means comprises a hollow body having an outer peripheral entrance surface and an inner peripheral exit surface, and the entrance surface and the exit surface are shaped such that a light beam exiting from the exit surface is The illumination device according to claim 2 or 3, wherein the illumination device is determined based on refraction of light so as to reach the object to be illuminated substantially uniformly. 5. The light incident surface of the light diffusing means has a conical shape or a truncated cone shape, and the light emitting surface of the light diffusing means has a spherical surface and a cylindrical surface continuous with the spherical surface. The lighting device according to claim 3 or 4. 6. The incident surface of the light diffusing means has a shape having a spherical surface and a cylindrical surface continuous with the spherical surface, and the emitting surface of the light diffusing means has a spherical surface having a curvature different from that of the incident surface. The illumination device according to claim 3 or 4, wherein the illumination device has a shape having a cylindrical surface continuous with the spherical surface. 7. The lighting device according to claim 2, wherein the light diffusing unit is made of translucent milky white resin. 8. The lighting device according to claim 2, wherein the light diffusing means is made of light-diffused glass. 9. The illumination according to claim 2, wherein the reflecting means has a cylinder surrounding the light diffusing means, and an inner surface of the cylinder is formed into a mirror surface. apparatus. 10. The illumination device according to claim 2, wherein the ring-shaped light source is an array of optical fibers arranged in a ring shape.