JP7157799B2 - Light irradiation device - Google Patents

Description

The present invention relates to a light irradiation device.

As a light irradiation device used in an inspection device for inspecting defects in a work, for example, Patent Document 1 discloses a light source, a plate shape having a front surface, a back surface, and a side peripheral surface, and the surface is attached to the workpiece to be inspected. a light guide plate arranged facing the light source and introducing the light from the light source from the side peripheral surface; is diffusely reflected and emitted from the surface.

The conventional light irradiation device has a cover body arranged to cover the back surface of the light guide plate, and has a structure in which the workpiece 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, part of the light introduced from the side peripheral surface of the light guide plate and directed toward the back side of the light guide plate is the light source of the diffuse reflection portion. Since the light 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 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 weak. . As a result, the workpiece could not be efficiently irradiated with light. Moreover, when viewed as a whole light guide plate, there is also a problem that the unevenness of the light is large between the edge side and the center side.

JP 2016-136124 A

Therefore, the main object of the present invention is to provide a light irradiation device that can efficiently irradiate a work with light and that has less light unevenness when viewed as a whole light guide plate. 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. and a light guide plate to be introduced, wherein the light introduced into the light guide plate from the side peripheral surface is internally reflected and emitted from the surface, wherein the light guide plate and further comprising a cover body provided with a through hole at a predetermined location, and a first region around a portion corresponding to the through hole on the back surface of the light guide plate includes the A diffuse reflection part that diffuses and reflects light introduced into the light guide plate from the side peripheral surface is provided, and a second region further outside the first region is provided with the light introduced into the light guide plate from the side peripheral surface. It is characterized by providing a total reflection portion that totally reflects the reflected light.

With such a configuration, since the total reflection portion is provided outside the diffuse reflection portion on the back surface of the light guide plate, the light from the light source introduced from the side peripheral surface of the light guide plate travels toward the back surface side of the light guide plate. Part of the light is reflected by the total reflection portion and guided toward the center of the light guide plate. As a result, more light is guided toward the center of the light guide plate, and more light is emitted from the center of the light guide plate. As a result, the workpiece can be efficiently irradiated with light. In addition, while the light emitted from the center side of the light guide plate is strong, the light emitted from the vicinity of the light source (outside) of the light guide plate is weakened. becomes smaller.

Further, the size of the hole of a cut surface obtained by cutting the through hole parallel to the rear surface of the light guide plate may decrease toward the light guide plate. With such a configuration, the installation area for the work of the camera arranged on the back side of the light guide plate is widened, and as a result, when the work and the camera are arranged with respect to the light irradiation device, there is a degree of freedom in their arrangement. Moreover, installation of each device becomes easier.

As a camera for observing a work, a line-shaped camera is sometimes used to efficiently observe the entire work. In this case, a slit-shaped through hole is preferable.

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

Further, for example, when the diffuse reflection layer is thin, 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, resulting in light loss. Therefore, a reflecting member may be further provided 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. With such a structure, 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 workpiece 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 a sectional view showing typically an inspection device concerning this embodiment. It is a schematic diagram which shows the positional relationship of the light-guide plate and light source of the light irradiation apparatus which concerns on the same embodiment. It is the typical perspective view which looked at the light irradiation apparatus which concerns on the same embodiment from the surface side of a light-guide plate. It is the typical perspective view which looked at the light irradiation apparatus which concerns on the same embodiment from the back surface side of a light-guide plate. It is a sectional view showing typically the structure near the light source of the light irradiation device concerning other embodiments. It is a schematic diagram which shows the relationship between the through-hole and 1st area|region which concern on other embodiment.

100 Light irradiation device 10 Light source 20 Light guide plate 21 Light guide plate surface 22 Light guide plate back surface 23 Light guide plate side peripheral surface 24 Diffuse reflection part 25 Total reflection part 30 Housing 40 Reflection member

A light irradiation device according to the present invention and an inspection device equipped with the light irradiation device will be described below with reference to the drawings.

An inspection apparatus A according to the present invention is used for inspecting defects (scratches, stains, inclusion of foreign matter, etc.) in a work W, and is installed, for example, in a transfer line for transferring the work W in a factory or the like. It is what is done.

<Embodiment>
As shown in FIG. 1, the inspection apparatus A according to the present embodiment is arranged on the opposite side of the work W with the light irradiation device 100 that irradiates the work W to be inspected with the light irradiation device 100 interposed therebetween. and 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.

1 to 4, the light irradiation device 100 has a plate shape having a light source 10, a front surface 21, a rear surface 22, and a side peripheral surface 23, and the front surface 21 is arranged to face the work W. , a light guide plate 20 through 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 of the light guide plate 20 and the housing. and a reflective member 40 disposed between the body 30 . The housing 30 is provided with a through hole 30a for observing the workpiece W with the camera C at a predetermined position covering the rear surface 22 of the light guide plate 20. As shown in FIG. The through-hole 30a of this 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 regular intervals along the side peripheral surface 23 of the light guide plate 20 , and the light emission direction thereof faces the side peripheral surface 23 . Moreover, the light source 10 further includes a lens extending along the side peripheral surface 23 in the light emitting direction. In this embodiment, the light source 10 is arranged to face the side peripheral surface 23 along the longitudinal direction of the light guide plate 20 with respect to the light guide plate 20 , and the side peripheral surface 23 along the width direction of the light guide plate 20 . is not placed in

The light guide plate 20 is a transparent plate having a rectangular shape in a plan view, and is made of, for example, an acrylic plate or a glass plate. The light guide plate 20 is arranged such that its longitudinal direction is parallel to the longitudinal direction of the slit-shaped through holes 30a. As shown in FIG. 2, on the rear surface 22 of the light guide plate 20, light is introduced into the light guide plate 20 from the side peripheral surfaces 23 of the first regions 22a, which are regions on both sides of the portion corresponding to the through hole 30a. A diffuse reflection portion 24 that diffuses and reflects the reflected light is provided along the longitudinal direction of the through hole 30a. In addition, on the rear surface 22 of the light guide plate 20, a second region 22b, which is a region closer to the end than the first region 22a, is provided with a total reflector that totally reflects light introduced into the light guide plate 20 from the side peripheral surface 23 thereof. A reflecting portion 25 is provided along the longitudinal direction of the through hole 30a. That is, the second region 22b is the region between the first region 22a and the side peripheral surface 23 on the rear surface 22 of the light guide plate 20, in other words, the peripheral region of the rear surface 22 of the light guide plate 20.

The diffuse reflection part 24 is obtained by stacking a diffuse reflection layer 24a on the first region 22a. The diffuse reflection portions 24 are preferably spaced apart from the light source 10 by 10 to 20 mm in the width direction of the light guide plate 20, and are formed in pairs with a spacing of 2 to 20 mm across 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 gaps. As the ink, white ink is used and is formed with a thickness of 20 to 25 μm. In addition, not only ink but also paint may be applied on the light guide plate 20 and laminated.

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

The cover body 31 is provided with the through hole 30 a , and the through hole 30 a 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. It is a shape that gradually becomes smaller with time. Further, the cover body 31 is provided with a connecting piece 31a for connecting to the side plate 32 at its side edge portion. Note that the cover body 31 has the same thickness at the portion facing the back surface 22 of the light guide plate 20 except for the connecting piece 31a.

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

The housing 30 sandwiches and supports the light guide plate 20 fitted in the frame of the side plate 32 between the cover portion 32b of the side plate 32 and the cover body 31. As shown in FIG. In this state, the cover portion 32b of the side plate 32 is arranged to cover the surface of the surface 21 of the light guide plate 20 opposite to the total reflection portion 25 . In addition, it is preferable that the housing 30 is made of, for example, a light-shielding and heat-radiating material. Specifically, it is preferably made of a metal such as an aluminum alloy.

The reflecting member 40 is a thin plate attached to the inner surface of the cover body 31 . Although it is arranged between the diffuse reflection part 24 provided on the back surface 22 of the light guide plate 20 and the cover body 31 in this embodiment, it may face part or all of the total reflection part 25 . Also, the reflecting member 40 is composed of, for example, a reflecting mirror, and is arranged with its reflecting surface directed toward the diffuse reflection section 24 side. The reflecting member 40 plays a role of reflecting, of the light introduced into the light guide plate 20 , the light transmitted through the diffuse reflection portion 24 to the light guide plate 20 side.

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

According to the inspection apparatus A according to this embodiment configured as described above, 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. Install camera C on 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 workpiece W is widened 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 enters the light guide plate 20 from the side peripheral surface 23 of the light guide plate 20 , and part of the light traveling toward the back surface 22 of the light guide plate 20 is reflected by the total reflection portion 25 . The light is totally reflected and guided to the center side of the light guide plate 20 . After being totally reflected by the inner surface of the surface 21 of the light guide plate 20 and diffusely reflected by the diffuse reflection portion 24 (diffuse reflection layer 24a), the light is emitted from the light guide plate 20 to the outside and the work W is irradiated. Some of the light directed toward the rear surface 22 of the light guide plate 20 is directly incident on the diffuse reflection portion 24 and diffusely reflected. be done. Of the light incident on the diffuse reflection portion 24 , the light transmitted through the diffuse reflection portion 24 is also reflected toward the light guide plate 20 by the reflecting member 40 and irradiated onto the work W. FIG.

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

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

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

Furthermore, with such a configuration, since the light guide plate 20 is interposed between the camera C and the work W, it is possible to prevent dirt such as dust from falling from the camera C side to the work W side.

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

In the above-described embodiment, the diffuse reflection layer 24a is laminated on the first region 22a to form the diffuse reflection portion 24. However, the diffuse reflection can be achieved by scratching the entire surface of the first region 22a by, for example, blasting. A portion 24 may be formed. Furthermore, the diffuse reflection part 24 may be formed by installing a member that diffuses and reflects light separately from the light guide plate 20 in the first region 22a.

Further, in the above-described embodiment, the through hole 30a is slit-shaped to match the line camera, but is not limited to this, and may be, for example, circular or rectangular. When the through hole 30a is circular or rectangular, the first region 22a is formed around the portion corresponding to the through hole 30a on the rear surface 22 of the light guide plate 20, and the second region 22b is formed outside thereof. do. Further, the light sources 10 are arranged all around the side peripheral surface 23 of the light guide plate 20 . Similarly, in the above-described embodiment, the light guide plate 20 is rectangular, but it is not limited to this, and may be, for example, circular.

The rear surface 22 of the light guide plate 20 in the above embodiment includes a region without the diffuse reflection portion 24 in a portion corresponding to the through hole 30a so that the workpiece W can be observed through the light guide plate 20 from the through hole 30a. It is good if there is Therefore, for example, if the through hole 30a has a circular shape, the first region 22a may extend inside the portion corresponding to the through hole 30a as shown in FIG. As shown in b), it may be formed outside 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 a portion other than the central portion of the cover body 31.

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

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

Claims (5)

a light source;
a light guide plate having a plate-like shape having a front surface, a back surface, and a side peripheral surface, the front surface facing the workpiece, and light from the light source being 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,
further comprising a cover body arranged to cover the back surface of the light guide plate and having through holes provided at predetermined locations;
On the back surface of the light guide plate, a first region around a portion corresponding to the through hole is provided with a diffuse reflection portion that diffusely reflects light introduced into the light guide plate from the side peripheral surface, and A second region further outside the first region is provided with a total reflection portion that totally reflects light introduced into the light guide plate from the side peripheral surface ,
The light irradiation device , further comprising: a reflecting member provided only between the diffuse reflection portion and the cover body, the reflecting member reflecting the light transmitted through the diffuse reflection portion toward the light guide plate . 2. The light irradiation device according to claim 1, wherein the light is emitted from a region of the surface of the light guide plate facing the diffuse reflection portion and the total reflection portion . 2. The light irradiation device according to claim 1, wherein a size of a cut surface obtained by cutting said through-hole parallel to the rear surface of said light guide plate decreases toward said light guide plate. 2. A light irradiation device according to claim 1, wherein said through hole is slit-shaped. 2. The light irradiation device according to claim 1, wherein the diffuse reflection part is formed by laminating a diffuse reflection layer on the entire surface of the first region.

Images