Inspection light irradiation device and inspection system

Abstract

To sufficiently perform heat radiation of LEDs while enlarging a light emitting surface of a light irradiation device for inspection.SOLUTION: A light irradiation device for inspection includes a plate-like light guide plate 2, and an LED mounting substrate 3 provided along an outer peripheral surface 2c of the light guide plate 2 and composed of a plurality of LEDs 32 and a wiring board 31. Light from the LEDs 32 is made incident on the inside of the light guide plate 2 from its outer peripheral surface 2c, is reflected on a first plate surface 2a of the light guide plate 2, is emitted outward from a second plate surface 2b of the light guide plate 2 and is applied to a workpiece W, and an imaging device 200 is configured to be able to image the workpiece W from the first plate surface 2a side of the light guide plate 2 through the light guide plate 2. It further includes a heat radiation member 10 thermally connected to the LED mounting substrate 3 and extending along the thickness direction of the light guide plate 2 on an outer side of the light guide plate 2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an inspection light irradiation device that irradiates light for purposes such as inspecting the surface of a product, and an inspection system that uses the inspection light irradiation device. [Background technology]

[0002] Conventionally, there has been known a light irradiation device (hereinafter also referred to as an omnidirectional light irradiation device) that can inspect an object such as a product (hereinafter also referred to as a workpiece) by irradiating it with light as uniform as possible from all directions. Such an omnidirectional light irradiation device does not cast shadows even if the inspection area of ​​the workpiece has a curved or uneven surface, and can highlight, for example, printed characters or color differences on the workpiece surface, making it suitable for inspecting spheres, R-shaped workpieces, soldered parts, etc.

[0003] Dome-shaped omnidirectional light irradiation devices are widely known, but because their height dimensions are somewhat large, recently, as shown in Patent Document 1, flat-type omnidirectional light irradiation devices have been developed that are thin and use a flat light guide plate.

[0004] This type of flat-plate type omnidirectional light irradiation device includes a flat light guide plate, an LED mounting board having a plurality of LEDs provided along the outer peripheral surface of the light guide plate, and a frame that houses the LED mounting board and supports the peripheral edge of the light guide plate. In addition, a large number of fine diffuse reflectors are provided at intervals on one surface of the light guide plate.

[0005] In this flat-plate type omnidirectional light irradiation device, light from the LED enters the light guide plate from its outer peripheral surface, is reflected by one of its plate surfaces, and is emitted to the outside from the other plate surface of the light guide plate to be irradiated onto the workpiece, and the workpiece can be imaged by an imaging device from one of its plate surfaces through the light guide plate. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-85808 Summary of the Invention [Problem to be solved by the invention]

[0007] The above-mentioned light irradiation device is flat to reduce the distance between the imaging device and the workpiece, so there is a preconceived notion that it is necessary to avoid increasing the dimensions in the thickness direction of the light guide plate. Therefore, it is thought that the heat dissipation performance of the light irradiation device can be improved by extending the heat dissipation member such as the thermal conductor that is in close contact with the back surface of the LED wiring board outward (perpendicular to the LED light-emitting surface) along the planar direction of the light guide plate.

[0008] However, when the heat dissipation member is provided as described above, the width dimension (dimension along the planar direction of the light guide plate) of the frame supporting the peripheral portion of the light guide plate increases, and the size of the non-light-emitting surface of the light irradiation device increases. In this case, if there is a restriction on the external size of the light irradiation device in a planar view, the width dimension of the frame increases, and the size of the light-emitting surface of the light guide plate decreases.

[0009] The present invention has been made to solve the above problems, and its main object is to increase the light emitting surface of the inspection light irradiation device while sufficiently dissipating heat from the LED. [Means for solving the problem]

[0010] That is, the inspection light irradiation device of the present invention comprises a flat light guide plate and an LED mounting board arranged along the outer peripheral surface of the light guide plate and consisting of a plurality of LEDs and a wiring board, wherein light from the LEDs enters the light guide plate from the outer peripheral surface thereof, is reflected by a first plate surface of the light guide plate, and is emitted to the outside from a second plate surface of the light guide plate to be irradiated onto a workpiece, and the workpiece can be imaged by an imaging device through the light guide plate from the first plate surface side of the light guide plate, and further comprises a heat dissipation member that is thermally connected to the LED mounting board and extends outward beyond the light guide plate along the thickness direction of the light guide plate.

[0011] In such an inspection light irradiation device, the heat dissipation member thermally connected to the LED-mounted substrate is configured to extend outward beyond the light guide plate along the thickness direction of the light guide plate, so that in order to improve the heat dissipation performance of the inspection light irradiation device, it is sufficient to extend the heat dissipation member along the thickness direction of the light guide plate, and it is not necessary to extend it along the planar direction of the light guide plate. As a result, even if there are restrictions on the external size of the inspection light irradiation device in a planar view, it is possible to reduce the non-light-emitting surface of the inspection light irradiation device and increase the light-emitting surface of the inspection light irradiation device, while still achieving sufficient heat dissipation from the LEDs.

[0012] The LED-mounted substrate is a wiring board having the plurality of LEDs mounted on the surface thereof, and it is desirable that the LEDs be side-view LEDs that emit light in the width direction of the wiring board when mounted on the wiring board. With this configuration, the thickness direction of the wiring board is the same as that of the light guide plate, and by thermally connecting the heat dissipation member to the rear surface of the wiring board, the heat dissipation member can be extended along the thickness direction of the light guide plate. As a result, heat from the rear surface of the wiring board can be transferred while maintaining a large cross-sectional area in the heat conduction direction, thereby enabling efficient heat dissipation.

[0013] As a specific arrangement mode of the LED-mounted substrate, it is desirable that the LED-mounted substrate is arranged so that the wiring substrate is located on the first plate surface side in the thickness direction of the light guide plate, and the LED is located on the second plate surface side in the thickness direction of the light guide plate. With this configuration, since the wiring board is located on the first plate surface side in the thickness direction of the light guide plate, the heat dissipation member thermally connected to the back surface of the wiring board also extends toward the first plate surface side in the thickness direction of the light guide plate. In other words, the heat dissipation member extends toward the imaging device, allowing the light guide plate to be closer to the workpiece. Furthermore, the inspection light irradiation device can be installed without the heat dissipation member interfering with the transport of the workpiece. As a result, the inspection system using the inspection light irradiation device of the present invention can be miniaturized. Furthermore, since the heat dissipation member is located on the opposite side of the workpiece, heat from the LED is less likely to be transmitted to the workpiece, reducing the risk of the inspection accuracy being affected by the temperature characteristics of the workpiece or the quality of the workpiece being degraded during inspection.

[0014] Regardless of the arrangement of the LED-mounted board described above, it is desirable that the heat dissipation member extend toward the first plate surface side in the thickness direction of the light guide plate relative to the LED-mounted board. With this configuration, the heat dissipation member extends toward the imaging device, allowing the light guide plate to be closer to the workpiece. Furthermore, the inspection light irradiation device can be installed without the heat dissipation member interfering with the transport of the workpiece. As a result, the inspection system using the inspection light irradiation device of the present invention can be made smaller. Furthermore, since the heat dissipation member is located on the opposite side of the workpiece, heat from the LED is less likely to be transmitted to the workpiece, reducing the risk of the inspection accuracy being affected by the temperature characteristics of the workpiece or the quality of the workpiece being degraded during inspection.

[0015] The light irradiation device for inspection of the present invention further includes a support member for supporting the LED-mounted substrate. In this configuration, in order to reduce the number of parts, it is desirable that the heat dissipation member be formed by the support member.

[0016] Furthermore, the inspection system according to the present invention is characterized by comprising the above-mentioned inspection light irradiation device and an imaging device that images the workpiece from the first plate surface side of the light guide plate through the light guide plate. This inspection system allows for sufficient heat dissipation from the LEDs while reducing the external size of the inspection light irradiation device in a plan view. Furthermore, because the heat dissipation member extends toward the imaging device, the heat dissipation member does not get in the way even when the light guide plate is brought closer to the workpiece. Therefore, the distance between the imaging device and the workpiece can be reduced. [Effects of the Invention]

[0017] According to the present invention configured as described above, the light emitting surface of the inspection light irradiation device can be increased while the heat of the LED can be sufficiently dissipated. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram showing an inspection system using an inspection light irradiation device according to an embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective cross-sectional view of the inspection light irradiation device according to the embodiment. [Figure 3] 2 is a plan view of the light guide plate of the embodiment as viewed from the first plate surface side. FIG. [Figure 4] FIG. 2 is an enlarged perspective cross-sectional view of the inspection light irradiation device according to the embodiment. [Figure 5] FIG. 10 is an enlarged perspective cross-sectional view of a modified embodiment of an inspection light irradiation device. [Figure 6] FIG. 10 is an enlarged cross-sectional view of a modified embodiment of an inspection light irradiation device. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the inspection light irradiation device according to the present invention will be described with reference to the drawings. Note that in all of the drawings shown below, parts are appropriately omitted or exaggerated for clarity. Identical components are given the same reference numerals, and their explanations will be omitted as appropriate.

[0020] <1.Device configuration> As shown in FIG. 1, the inspection light irradiation device 100 of this embodiment is thin and flat overall, and has the function of canceling out shadows caused by curved surfaces and slight unevenness on the surface of the workpiece W by irradiating the workpiece W, which is the object of inspection, with light as uniform as possible from almost all directions (almost 180° in all directions).

[0021] More specifically, as shown in Figures 1 and 2, this inspection light irradiation device 100 comprises a flat light guide plate 2, an LED-mounted substrate 3 that is arranged along the outer peripheral surface 2c of the light guide plate 2 and has a plurality of LEDs 32 mounted thereon, and a frame body 4 that houses the LED-mounted substrate 3 and supports the peripheral portion of the light guide plate 2.

[0022] As shown in FIG. 1, the inspection light irradiation device 100 of this embodiment is used in a product inspection system Z that irradiates a predetermined irradiation area of ​​a workpiece W with light, captures an image of the predetermined irradiation area with an imaging device 200, and imports the obtained image data into an image processing device 300 to perform automatic surface inspection for the presence or absence of scratches, etc.

[0023] Each part of the inspection light irradiation device 100 will be described below.

[0024] The light guide plate 2 is, for example, a transparent plate made of resin (e.g., PMMA) having a uniform thickness and a circular shape. In the light guide plate 2, one of the opposing parallel plate surfaces (hereinafter, the first plate surface) 2a is formed with a diffuse reflection section 5 that diffuses or reflects light (see FIG. 3), and the other plate surface (hereinafter, the second plate surface) 2b is smoothed to a mirror finish. Here, the first plate surface 2a is the surface that faces the imaging device 200, and the second plate surface 2b is the surface that faces the workpiece W.

[0025] The diffuse reflection portion 5 diffuses or reflects light that has entered the light guide plate 2 toward the second plate surface 2b, and is, for example, a large number of minute recesses formed on the first plate surface 2a. Note that "diffusion" as used in this specification also includes the spread of light by reflection from, for example, a spherical surface.

[0026] 3, the diffuse reflecting portions 5 are, for example, partially concave spherical portions cut into the first plate surface 2a of the light guide plate 2, and the diffuse reflecting portions 5 are regularly aligned on square lattice points. Note that the shape and arrangement of the diffuse reflecting portions 5 are not limited to this and can be changed in various ways.

[0027] 1 and 2, the LED-mounted substrate 3 has a plurality of LEDs 32 mounted on the surface of an annular wiring substrate 31 that surrounds the outer peripheral surface 2c of the light guide plate 2, along the circumferential direction of the wiring substrate 31. Here, the plurality of LEDs 32 are arranged in a row at a predetermined pitch, more specifically, at equal pitches.

[0028] The LEDs 32 are, for example, surface-mounted LEDs, and are available in a variety of colors, including white, red, and blue, but white LEDs are used here. More specifically, the LEDs 32 are side-view LEDs that emit light in the width direction of the wiring board 31 when mounted on the wiring board 31, that is, toward the inside in the radial direction of the wiring board 31. The multiple LEDs 32 are provided at the inside end in the radial direction of the wiring board 31 to prevent light loss due to light hitting the wiring board 31 and to reduce the distance between the LEDs 32 and the outer peripheral surface 2c of the light guide plate 2 as much as possible to improve light utilization efficiency.

[0029] As shown in Figures 1, 2 and 4, the frame body 4 has a circular frame shape and includes a circular support member 41 that supports the LED-mounted substrate 3, and a circular case member 42 that is attached to the support member 41 and clamps the peripheral portion of the light guide plate 2 together with the support member 41.

[0030] As shown in Figure 4, the support member 41 has an inner step portion 41a on which the light guide plate 2 is placed and which supports the peripheral portion of the light guide plate 2, and an outer step portion 41b formed radially outside the inner step portion 41a on which the LED-mounted substrate 3 is placed and which supports the LED-mounted substrate 3.

[0031] By placing the light guide plate 2 on the inner step portion 41a, the first plate surface 2a at the peripheral edge of the light guide plate 2 is covered by the support member 41. By placing the light guide plate 2 on the inner step portion 41a and the LED-mounted substrate 3 on the outer step portion 41b, the light guide plate 2 and the LED-mounted substrate 3 are positioned. The light-emitting surfaces of the LEDs 32 mounted on the LED-mounted substrate 3 face the outer peripheral surface 2c of the light guide plate 2. With this configuration, light emitted from the LEDs 32 enters the light guide plate 2 from the outer peripheral surface 2c. A viscoelastic heat conductor 6 is provided between the upper surface of the outer step portion 41b of the support member 41 and the back surface of the LED-mounted substrate 3. In addition, in order to absorb thermal expansion and contraction of the light guide plate 2, the LED mounting substrate 3 and / or the support member 41, a clearance may be provided between the inner step portion 41a and the light guide plate 2, and / or between the outer step portion 41b and the LED mounting substrate 3.

[0032] The case member 42 is fixed to the outer peripheral surface of the support member 41 with screws or the like, and by being fixed to the support member 41, it covers the LED-mounted board 3 and sandwiches the light guide plate 2 between itself and the support member 41. By fixing the case member 42 to the support member 41, the second plate surface 2b at the peripheral portion of the light guide plate 2 is covered by the case member 42. In this embodiment, a cover plate 7 that covers the second plate surface 2b of the light guide plate 2 is provided via a spacer 8, and the case member 42 sandwiches the peripheral portion of the light guide plate 2 via the cover plate 7 and the spacer 8.

[0033] In this embodiment, the outer size of the support member 41 is configured to be larger than the outer size of the mounted LED board 3 by only approximately the thickness of the case member 42 (for example, approximately 1 mm). Specifically, as shown in FIG. 4 , an attachment step 41c for attaching the case member 42 is formed on the outer peripheral surface of the support member 41, and the attachment step 41c is formed up to the vicinity of the outer peripheral surface of the mounted LED board 3 in a direction perpendicular to the imaging direction. Furthermore, the depth dimension of the attachment step 41c perpendicular to the imaging direction is substantially the same as the thickness dimension of the mounting cylindrical portion 421 of the case member 42. With this configuration, the outer side of the mounted LED board 3 is larger only by approximately the thickness of the mounting cylindrical portion 421 of the case member 42, and the area of ​​the non-light-emitting surface of the inspection light irradiation device 100 can be reduced.

[0034] In the inspection light irradiation device 100 configured as described above, the light emitted from the LEDs 32 enters the light guide plate 2 from the outer peripheral surface 2c and travels inside while repeatedly being totally reflected between the opposing plate surfaces of the light guide plate 2. Most of the light then hits the diffuse reflector 5 as it travels, where it is diffused or reflected, and is emitted to the outside from the second plate surface 2b of the light guide plate 2. More specifically, as described above, the peripheral portion of the light guide plate 2 is covered by the frame 4, and so light is emitted from inside the frame 4 at the second plate surface 2b of the light guide plate 2. This makes the second plate surface 2b the light-emitting surface.

[0035] 2. Configuration of heat dissipation member 10 As shown in Figures 1, 2 and 4, the inspection light irradiation device 100 of this embodiment is thermally connected to the LED-mounted substrate 3 and further includes a heat dissipation member 10 that extends outward from the light guide plate 2 along the thickness direction of the light guide plate 2 (the imaging direction of the imaging device 200).

[0036] The heat dissipation member 10 of this embodiment dissipates heat generated by the LEDs 32 to the outside, and is annular and made of a support member 41. The heat dissipation member 10 made of the support member 41 extends toward the first plate surface 2a in the thickness direction of the light guide plate 2 with respect to the LED-mounted substrate 3. The heat dissipation member 10 made of the support member 41 also serves as a window frame for the imaging device 200.

[0037] Here, the LED-mounted substrate 3 is provided so that the wiring board 31 is located on the first plate surface 2a side in the thickness direction of the light guide plate 2 and the LEDs 32 are located on the second plate surface 2b side in the thickness direction of the light guide plate 2, and the heat dissipation member 10 (support member 41) thermally connected to the back surface of the wiring board 31 extends toward the first plate surface 2a side in the thickness direction of the light guide plate 2. In other words, the heat dissipation member 10 (support member 41) extends toward the imaging device 200, allowing the light guide plate 2 to be closer to the workpiece W. With this configuration, the heat dissipation member 10 dissipates heat from the LEDs 32 into an open space on the imaging device 200 side.

[0038] In the above-described inspection light irradiation device 100, the second plate surface 2b of the light guide plate 2 is disposed so as to face the workpiece W, and the workpiece W is illuminated with diffused light emitted from the second plate surface 2b. The illuminated workpiece W is imaged by the imaging device 200 from the opposite side of the light guide plate 2, i.e., from the first plate surface 2a side of the light guide plate 2. Here, the heat dissipation member 10 extends toward the imaging device 200 and is disposed so as to surround the imaging device 200. In other words, the tip of the imaging device 200 can be disposed inside the heat dissipation member 10, and the heat dissipation member 10 does not get in the way when the imaging device 200 is brought close to the light guide plate 2.

[0039] <3. Effects of this embodiment> According to the inspection light irradiating device 100 of this embodiment configured as described above, the heat dissipation member 10 thermally connected to the LED-mounted substrate 3 is configured to extend outward beyond the light guide plate 2 along the thickness direction of the light guide plate 2, so that in order to improve the heat dissipation performance of the inspection light irradiating device 100, it is sufficient to extend the heat dissipation member 10 along the thickness direction of the light guide plate 2, and it is not necessary to extend it along the planar direction of the light guide plate 2. As a result, even if there is a restriction on the external size of the inspection light irradiating device 100 in a planar view, it is possible to reduce the non-light-emitting surface of the inspection light irradiating device 100 and increase the light-emitting surface of the inspection light irradiating device 100, while still allowing sufficient heat dissipation from the LEDs 32.

[0040] <4. Other embodiments> The present invention is not limited to the above-described embodiment.

[0041] For example, the LED 32 in the above embodiment is a side-view type LED, and the LED mounting substrate 3 is configured to be arranged parallel to the light guide plate 2, but as shown in Figure 5, the LED 32 may also emit light in a direction perpendicular to the wiring substrate 31.

[0042] In this case, the wiring board 31 of the LED-mounted board 3 is disposed so that its plate surface faces the outer peripheral surface 2c of the light guide plate 2. The support member 41 serving as the heat dissipation member 10 has the same configuration as in the above embodiment, extending in the thickness direction of the light guide plate 2.

[0043] 6, in a configuration in which the LEDs 32 mounted on the LED mounting substrate 3 emit light in the thickness direction of the light guide plate 2 (thickness direction of the wiring substrate 31), the light emitted from the LEDs 32 may be reflected by a reflecting mirror 11 and made to enter the outer peripheral surface 2c of the light guide plate 2. Note that, in the configuration in FIG. 6, the reflecting mirror 11 is inclined at 45 degrees with respect to the light emission direction of the LEDs 32, but the arrangement of the reflecting mirror 11 can be changed as appropriate depending on the relative positions of the LEDs 32 and the light guide plate 2.

[0044] Although the light guide plate 2 in the above embodiment has a circular shape in a plan view, it may have a rectangular shape in a plan view. In this case, the LED-mounted substrates 3 are provided corresponding to the four sides of the light guide plate 2, and are configured to emit light toward each side surface of the light guide plate 2. Furthermore, the light guide plate 2 may have a polygonal shape such as a triangular, pentagonal, or hexagonal shape in a plan view.

[0045] Furthermore, although the heat dissipation member 10 in the above embodiment is formed integrally with the support member 41, it may be formed separately from the support member 41. In this case, the heat dissipation member 10 is connected to the support member 41 directly or via a thermal conductor. With this configuration, the support member 41 can be used as a general-purpose component, and the heat dissipation member 10 can be changed as appropriate to match the amount of heat generated by the LEDs 32.

[0046] Furthermore, the heat dissipation member 10 may be solid as in the above embodiment, or may be configured to include a plurality of heat dissipation fins.

[0047] Furthermore, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0048] Z···Inspection System W ···Work 100 Inspection light irradiation device 200 Imaging device 2...Light guide plate 2a...1st plate surface 2b...Second plate surface 2c...outer circumferential surface 3 LED mounting board 31 Wiring board 32 LEDs 41 Support member 10 Heat dissipation member

Claims

1. The light guide device includes a flat light guide plate and an LED-mounted substrate having a plurality of LEDs provided on the surface of a wiring board surrounding the outer peripheral surface of the light guide plate, wherein light from the LEDs enters the light guide plate from the outer peripheral surface thereof, is diffused or reflected by a first plate surface of the light guide plate, and is emitted to the outside from a second plate surface of the light guide plate to be irradiated onto a workpiece, and the workpiece can be imaged by an imaging device from the first plate surface side of the light guide plate through the light guide plate, the LED-mounted substrate is configured to mount the plurality of LEDs on a surface of the wiring substrate that is aligned with a planar direction of the light guide plate, on a side of the wiring substrate that faces the light guide plate in a width direction of the wiring substrate; a heat dissipation member that is thermally connected to a rear surface of the wiring board and extends outward beyond the light guide plate along a thickness direction of the light guide plate, The length of the heat dissipation member in the thickness direction of the light guide plate is greater than the length of the wiring board.

2. 2. The light irradiation device for inspection according to claim 1, wherein the LED is a side-view type LED that emits light in a width direction of the wiring board when mounted on the wiring board.

3. 3. The inspection light irradiation device according to claim 1, wherein the LED mounting substrate is arranged so that the wiring substrate is located on the first plate surface side in the thickness direction of the light guide plate, and the LED is located on the second plate surface side in the thickness direction of the light guide plate.

4. The inspection light irradiation device according to claim 1 , wherein the heat dissipation member extends toward the first plate surface in a thickness direction of the light guide plate.

5. a support member for supporting the LED-mounted substrate; The light irradiation device for inspection according to claim 1 , wherein the heat dissipation member is configured by the support member.

6. The inspection light irradiation device according to any one of claims 1 to 5, an imaging device that images the workpiece from the first plate surface side of the light guide plate through the light guide plate.

Images