JPWO2019208752A1 - Light irradiation device - Google Patents

Abstract

Provided is a light irradiation device which has less light loss, can efficiently irradiate a work with light, and has less light unevenness when viewed as a light guide plate as a whole. A light source and a light guide plate having a plate shape having a front surface, a back surface, and a side peripheral surface, the surface of which is arranged toward a work to be inspected, and the light of the light source is introduced from the side peripheral surface. The light irradiation device is configured so that the light introduced into the light guide plate from the side peripheral surface is internally reflected and emitted from the front surface so as to cover the back surface of the light guide plate. A cover body that is arranged and provided with a through hole at a predetermined position is further provided, and on the back surface of the light guide plate, the guide is provided from the side peripheral surface to the first region around the portion corresponding to the through hole. A diffuse reflection portion that diffusely reflects the light introduced into the light plate is provided, and the light introduced into the light guide plate from the side peripheral surface is applied to the second region further outside the first region. A total reflection unit that totally reflects is provided.

Description

The present invention relates to a light irradiation device.

As a light irradiation device used for an inspection device for inspecting defects in a work, for example, Patent Document 1 describes a work having a light source and a plate shape having a front surface, a back surface, and a side peripheral surface, and the surface of which is an inspection target. Light introduced from the side peripheral surface of the light guide plate by a diffuse reflection portion provided on the back surface of the light guide plate, which is provided with a light guide plate which is arranged so as to face and the light of the light source is introduced from the side peripheral surface. Is disclosed to have a structure in which light is diffusely reflected and ejected from the surface.

The conventional light irradiation device includes a cover body arranged so as to cover the back surface of the light guide plate, and has a structure in which the work is observed through a through hole provided in the center of the cover body. ..

However, in the conventional light irradiation device in which the diffuse reflection portion is formed up to the peripheral edge of the light guide plate, a part of the light introduced from the side peripheral surface of the light guide plate and directed to the back surface side of the light guide plate is a light source of the diffuse reflection portion. Since it is diffusely reflected in the vicinity, the light emitted from the vicinity of the light source of the light guide plate, that is, the end side far from the through hole of the light guide plate is extremely strong, and the light emitted from the center side of the light guide plate is weakened. .. As a result, the work could not be efficiently irradiated with light. Further, when the light guide plate as a whole is viewed, there is also a problem that the light unevenness is large between the end side and the center side.

Japanese Unexamined Patent Publication No. 2016-136124

Therefore, the main object of the present invention is to provide a light irradiation device capable of efficiently irradiating a work with light and having a small light unevenness when viewed as a light guide plate as a whole. Is.

That is, the light irradiation device according to the present invention has a plate shape having a light source, a front surface, a back surface, and a side peripheral surface, the front surface is arranged toward the work, and the light of the light source is emitted from the side peripheral surface. A light irradiation device including a light guide plate to be introduced, in which light introduced into the light guide plate from the side peripheral surface is internally reflected and emitted from the surface, and the light guide plate is provided. A cover body provided with a through hole at a predetermined position is further provided so as to cover the back surface of the light guide plate, and the first region around the portion corresponding to the through hole on the back surface of the light guide plate is described as described above. A diffuse reflection portion that diffusely reflects the light introduced into the light guide plate from the side peripheral surface is provided, and the second region further outside the first region is introduced into the light guide plate from the side peripheral surface. It is characterized in that a total reflection portion that totally reflects the light is provided.

In such a case, since the total reflection portion is provided outside the diffuse reflection portion on the back surface of the light guide plate, the light of the light source introduced from the side peripheral surface of the light guide plate goes toward the back surface side of the light guide plate. A part of the light is reflected by the total reflection part and guided to the center side of the light guide plate. As a result, the light guided to the center side of the light guide plate is increased, and the light emitted from the center side of the light guide plate is strengthened. As a result, the work can be efficiently irradiated with light. Further, while the light emitted from the center side of the light guide plate becomes stronger, the light emitted from the vicinity (outside) of the light source of the light guide plate weakens. The unevenness of is reduced.

Further, the size of the hole on the cut surface obtained by cutting the through hole in parallel with the back surface of the light guide plate may become smaller toward the light guide plate. In such a case, the installation area for the work of the camera arranged on the back surface side of the light guide plate is widened, and thus, when the work and the camera are arranged with respect to the light irradiation device, the degree of freedom in the arrangement is increased. Furthermore, the installation of each device becomes easier.

Further, as a camera for observing the work, a line-shaped camera may be used for efficiently observing the entire work. In this case, a camera having a slit-shaped through hole is preferable.

Further, the diffuse reflection portion may be a diffuse reflection layer laminated on the entire surface of the first region. With such a case, for example, since the diffuse reflection layer can be formed by printing, the number of parts constituting the light irradiation device can be reduced, and the productivity is improved. Further, even if the shape of the diffuse reflection portion is complicated, it can be easily formed.

Further, for example, when the diffuse reflection layer is thin, a part of the light incident on the diffuse reflection portion is transmitted, and the light transmitted through the diffuse reflection portion is absorbed by the cover body to cause a loss of light. Therefore, a reflective member that reflects the light transmitted through the diffuse reflection portion toward the light guide plate may be further provided between the diffuse reflection portion of the light guide plate and the cover body. In such a case, the light transmitted through the diffuse reflection portion is reflected by the reflecting member and returned to the light guide plate, so that the loss of light can be reduced. As a result, the work can be irradiated with light more efficiently.

According to the light irradiation device having such a configuration, it is possible to efficiently irradiate the work with light and to improve the uniformity of the light emitted from the light guide plate.

It is sectional drawing which shows typically the inspection apparatus which concerns on this embodiment. It is a schematic diagram which shows the positional relationship between the light guide plate and the light source of the light irradiation apparatus which concerns on this embodiment. It is a schematic perspective view which looked at the light irradiation apparatus which concerns on this embodiment from the surface side of the light guide plate. It is a schematic perspective view which looked at the light irradiation apparatus which concerns on this embodiment from the back surface side of a light guide plate. It is sectional drawing which shows typically the structure in the vicinity of the light source of the light irradiation apparatus which concerns on other embodiment. It is a schematic diagram which shows the relationship between the through hole and the 1st region which concerns on other embodiment.

100 Light irradiation device 10 Light source 20 Light guide plate 21 Front surface of light guide plate 22 Back surface of light guide plate 23 Side peripheral surface of light guide plate 24 Diffuse reflection part 25 Total reflection part 30 Housing 40 Reflection member

Hereinafter, the light irradiation device according to the present invention and the inspection device provided with the light irradiation device will be described with reference to the drawings.

The inspection device A according to the present invention is used for inspecting defects (scratches, dirt, foreign matter, etc.) of the work W, and is installed in a transport line for transporting the work W, for example, in a factory or the like. Is to be done.

<Embodiment>
As shown in FIG. 1, the inspection device A according to the present embodiment is arranged on the opposite side of the work W and the light irradiation device 100 that irradiates the work W with the light irradiation device 100. It is equipped with a camera C to be used. As the camera C, for example, a CCD camera can be used. The camera of this embodiment is a line camera.

As shown in FIGS. 1 to 4, the light irradiation device 100 has a plate shape having a light source 10, a front surface 21, a back surface 22, and a side peripheral surface 23, and the surface 21 is arranged toward the work W. A light guide plate 20 into which the light of the light source 10 is introduced from the side peripheral surface 23, a housing 30 that supports the light guide plate 20 and the light source 10 and covers the back surface 22 of the light guide plate 20, and a back surface 22 and a casing of the light guide plate 20. It includes a reflective member 40 arranged between the body 30 and the body 30. The housing 30 is provided with a through hole 30a for observing the work W by the camera C at a predetermined position covering the back surface 22 of the light guide plate 20. The through hole 30a of the present embodiment has a slit shape extending along the longitudinal direction of the line camera (see FIG. 4).

The light source 10 includes a plurality of LEDs arranged at equal intervals along the side peripheral surface 23 of the light guide plate 20, and the light emitting direction thereof faces the side peripheral surface 23. Further, the light source 10 further includes a lens extending along the side peripheral surface 23 in the light emitting direction thereof. In the present embodiment, the light source 10 is arranged with respect to the light guide plate 20 so as to face the side peripheral surface 23 along the longitudinal direction of the light guide plate 20, and the side peripheral surface 23 along the width direction of the light guide plate 20. Not placed in.

The light guide plate 20 is a transparent plate having a rectangular shape in a plan view. For example, the light guide plate 20 is made of an acrylic plate, a glass plate, or the like, and the surface 21 is coated with an antireflection coating. The light guide plate 20 is arranged so that its longitudinal direction is parallel to the longitudinal direction of the slit-shaped through hole 30a. As shown in FIG. 2, in the back surface 22 of the light guide plate 20, the first region 22a, which is a region on both sides of the portion corresponding to the through hole 30a, is introduced into the light guide plate 20 from the side peripheral surface 23. A diffuse reflection portion 24 that diffusely reflects the light is provided along the longitudinal direction of the through hole 30a. Further, on the back surface 22 of the light guide plate 20, the second region 22b, which is a region on the end side of the first region 22a, totally reflects the light introduced into the light guide plate 20 from the side peripheral surface 23. The reflecting portion 25 is provided along the longitudinal direction of the through hole 30a. That is, the second region 22b is a region between the first region 22a and the side peripheral surface 23 on the back surface 22 of the light guide plate 20, in other words, a peripheral region on the back surface 22 of the light guide plate 20.

The diffuse reflection unit 24 is formed by laminating a diffuse reflection layer 24a on the first region 22a. The diffuse reflection portions 24 are preferably provided at a distance of 10 to 20 mm from the light source 10 in the width direction of the light guide plate 20, and are formed in pairs at intervals of 2 to 20 mm so as to sandwich the through hole 30a. The diffuse reflection layer 24a of the present embodiment is formed by printing ink on the entire surface of the first region 22a without any gaps. As the ink, white ink is used, and this is formed with a thickness of 20 to 25 μm. In addition to this, not only ink but also paint may be applied on the light guide plate 20 and laminated.

The housing 30 is formed in a rectangular shape in a plan view and supports the light guide plate 20 and the light source 10. Specifically, the housing 30 includes a cover body 31 arranged so as to cover the back surface 22 of the light guide plate 20, and a frame-shaped side plate 32 arranged so as to surround the side peripheral surface 23 of the light guide plate 20. It has.

The cover body 31 includes the through hole 30a, and the through hole 30a is formed in the central portion of the cover body 31 in the width direction along the longitudinal direction of the cover body 31. Further, the through hole 30a has a substantially V-shaped cross section, and specifically, the size of the hole on the cut surface when cut in parallel with the back surface 22 of the light guide plate 20 faces the back surface 22 of the light guide plate 20. The shape is gradually reduced. Further, the cover body 31 is provided with a connection piece 31a for connecting to the side plate 32 at its side edge portion. The cover body 31 has the same thickness as the portion facing the back surface 22 of the light guide plate 20 except for the connection piece 31a.

The side plate 32 supports the light source 10 in a recess 32a provided on the inner side surface of the light guide plate 20 facing the side peripheral surface 23. Further, the side plate 32 has a cover portion 32b extending inward from the inner side surface thereof to cover the surface 21 of the light guide plate 20. Further, the side plate 32 is provided with a mounting groove 32c used when the light irradiation device 100 is installed on the outer surface thereof.

The housing 30 supports the light guide plate 20 fitted in the frame of the side plate 32 by sandwiching it between the cover portion 32b of the side plate 32 and the cover body 31. In this state, the cover portion 32b of the side plate 32 is arranged so as to cover the surface of the surface 21 of the light guide plate 20 opposite to the total reflection portion 25. The housing 30 is preferably made of, for example, a material having a light-shielding property and a heat-dissipating property. Specifically, it is preferably formed of a metal such as an aluminum alloy.

The reflective member 40 is a thin plate attached to the inner surface of the cover body 31. In the present embodiment, it is arranged between the diffuse reflection portion 24 provided on the back surface 22 of the light guide plate 20 and the cover body 31, but it may face a part or all of the total reflection portion 25. Further, the reflecting member 40 is composed of, for example, a reflecting mirror, and is arranged in a state where the reflecting surface thereof faces the diffuse reflection portion 24 side. Then, the reflecting member 40 plays a role of reflecting the light transmitted through the diffuse reflection unit 24 to the light guide plate 20 side among the light introduced into the light guide plate 20.

In the present embodiment, the diffuse reflection portion 24 and the reflection member 40 are sandwiched between the light guide plate 20 and the cover body 31, and the total reflection portion 25 and the cover body 31 on the back surface 22 of the light guide plate 20 An air layer AL is formed between the two.

According to the inspection device A according to the present embodiment configured in this way, first, the light irradiation device 100 is installed so that the front surface 21 of the light guide plate 20 faces the work W side, and the back surface 22 side of the light guide plate 20 is installed. Camera C is installed in. Since the through hole 30a of the light irradiation device 100 has a substantially V-shaped cross section, the installation area of the camera C with respect to the work W becomes wider as shown in FIG.

Then, the work W is irradiated with light from the light irradiation device 100. At this time, the light emitted from the light source 10 is incident on the light guide plate 20 from the side peripheral surface 23 of the light guide plate 20, and a part of the light toward the back surface 22 side of the light guide plate 20 is totally reflected by the total reflection unit 25. It is totally reflected and guided to the center side of the light guide plate 20. Then, it is totally reflected on the inner surface of the surface 21 of the light guide plate 20, diffusely reflected by the diffuse reflection unit 24 (diffuse reflection layer 24a), and then ejected from the light guide plate 20 to the outside to irradiate the work W. Some of the light directed to the back surface 22 side of the light guide plate 20 is directly incident on the diffuse reflection unit 24 and diffusely reflected, and such light is also emitted to the outside from the light guide plate 20 to irradiate the work W. Will be done. Of the light incident on the diffuse reflection unit 24, the light transmitted through the diffuse reflection unit 24 is also reflected by the reflection member 40 toward the light guide plate 20 and irradiated to the work W.

Then, the work W irradiated with light in this way is imaged by the camera C through the through hole 30a, and the work W is inspected based on the image or the like obtained by the imaging.

Thus, according to the inspection device A of the present embodiment, since the total reflection portion 25 is provided on the outside of the diffuse reflection portion 24 on the back surface 22 of the light guide plate 20, it is introduced from the side peripheral surface 23 of the light guide plate 20. Of the light from the light source, a part of the light toward the back surface 22 side of the light guide plate 20 is reflected by the total reflection unit 25 and guided to the center side of the light guide plate 20. Therefore, although the light emitted from the vicinity (end) of the light source 10 of the light guide plate 20 is weakened, the light emitted from the inside of the light guide plate 20 becomes strong. As a result, the work W can be efficiently irradiated with even light from the entire surface of the light guide plate 20.

Further, since the diffuse reflection portion 24 is formed by printing ink, it can be easily formed. Further, since the light transmitted through the diffuse reflection unit 24 is reflected by the reflection member 40 toward the light guide plate 20, the loss of light can be further eliminated.

Further, in such a case, since the light guide plate 20 is interposed between the camera C and the work W, it is possible to prevent dust and the like from falling from the camera C side to the work W side.

<Other Embodiments>
As another embodiment, the cover body 31 as shown in FIG. 5 can be mentioned. Specifically, in the cover body 31 shown in FIG. 5, the side plate 32 side is thicker than the through hole 30a side. An air layer AL is formed between the thickly formed side plate 32 side of the cover body 31 and the back surface 22 (specifically, the total reflection portion 25) of the light guide plate 20. In such a case, the thickness of the cover body 31 in the vicinity of the light source 10 is increased, so that the heat generated by the light source 10 can be dissipated more efficiently.

Further, in the above embodiment, the diffuse reflection layer 24a is laminated on the first region 22a to form the diffuse reflection portion 24. However, for example, the entire surface of the first region 22a is scratched by blasting to cause diffuse reflection. The portion 24 may be formed. Further, a member that diffusely reflects light different from the light guide plate 20 may be installed in the first region 22a to form the diffuse reflection portion 24.

Further, in the above-described embodiment, the through hole 30a is formed into a slit shape in accordance with the line camera, but the present invention is not limited to this, and for example, a circular shape or a rectangular shape may be used. When the through hole 30a is circular or rectangular, the first region 22a is formed on the back surface 22 of the light guide plate 20 around the portion corresponding to the through hole 30a, and the second region 22b is formed on the outside thereof. To do. Further, the light source 10 is arranged on the entire circumference of the side peripheral surface 23 of the light guide plate 20. Similarly, in the above-described embodiment, the light guide plate 20 has a rectangular shape, but the present invention is not limited to this, and may be, for example, a circular shape or the like.

The back surface 22 of the light guide plate 20 in the above embodiment includes a region corresponding to the through hole 30a without the diffuse reflection portion 24 so that the work W can be observed from the through hole 30a through the light guide plate 20. I just need to be there. Therefore, for example, assuming that the through hole 30a has a circular shape, even if the first region 22a is formed up to the inside of the portion corresponding to the through hole 30a as shown in FIG. 6A, FIG. As shown in b), it may be formed on the outside of the portion corresponding to the through hole 30a.

Further, in the above embodiment, the through hole 30a is formed in the central portion of the cover body 31, but the through hole 30a may be formed in other than the central portion of the cover body 31.

In addition, the present invention is not limited to each of the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

According to the light irradiation device according to the present invention, it is possible to efficiently irradiate the work with light and to improve the uniformity of the light emitted from the light guide plate.

Claims (5)

Light source and
It has a plate shape having a front surface, a back surface, and a side peripheral surface, and is provided with a light guide plate in which the front surface is arranged toward the work and the light of the light source is introduced from the side peripheral surface.
A light irradiation device configured such that light introduced into the light guide plate from the side peripheral surface is internally reflected and emitted from the surface.
A cover body is further provided so as to cover the back surface of the light guide plate and provided with through holes at predetermined positions.
On the back surface of the light guide plate, a diffuse reflection portion that diffusely reflects the light introduced into the light guide plate from the side peripheral surface is provided in the first region around the portion corresponding to the through hole, and the light guide plate is provided. A light irradiation device characterized in that a total reflection portion that totally reflects light introduced into the light guide plate from the side peripheral surface is provided in a second region further outside the first region. The light irradiation device according to claim 1, wherein the size of the hole in the cut surface obtained by cutting the through hole in parallel with the back surface of the light guide plate becomes smaller toward the light guide plate. The light irradiation device according to claim 1, wherein the through hole has a slit shape. The light irradiation device according to claim 1, wherein the diffuse reflection unit is formed by laminating a diffuse reflection layer on the entire surface of the first region. The light irradiation device according to claim 1, further comprising a reflecting member between the diffuse reflection portion of the light guide plate and the cover body to reflect the light transmitted through the diffuse reflection portion toward the light guide plate side.

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