JP7429658B2 - light irradiation device - Google Patents

Description

The present invention relates to a light irradiation device and the like that uses LEDs arranged in a row as a light source, and particularly to one that is suitably used for inspecting the surface of a workpiece (product), reading marks, and the like.

As shown in FIG. 1 of Patent Document 1 below, a conventional light irradiation device of this type includes a housing having a long and narrow light emitting surface, and a long printed wiring board (hereinafter referred to as (also simply referred to as a wiring board), and a plurality of LEDs mounted in a row along the longitudinal direction of the surface of the wiring board. In addition, in order to dissipate heat from the LED, a linear band-shaped heat transfer body having viscoelasticity is placed between the back surface of the printed wiring board and the bottom plate of the casing. is configured to be able to be emitted from the bottom plate of the housing via the heat transfer body.

By the way, a resistance element may be arranged on the back surface of a wiring board. In this case, the heat transfer body must be recessed by the volume of the resistance element, but depending on the size of the resistance element, this volume cannot be absorbed by the recess of the heat transfer body, resulting in excessive force on the wiring board. Problems such as bending may occur.

Therefore, in FIG. 6 and paragraph 0037 of Patent Document 1, the inner surface of the bottom plate of the casing has a shape in which recesses and protrusions extending in the longitudinal direction are repeated, that is, when viewed from a cross section, the surface of the bottom plate is wavy. At the same time, the volume of the resistance element can be effectively reduced by setting the recess so that it is directly below the resistance element, so that the heat transfer body immediately below the resistance element is recessed in advance following the recess on the surface of the bottom plate. It is also stated that it can be absorbed.

However, in such a configuration, the surface of the heat transfer body is uneven to follow the inner surface of the bottom plate of the casing, so a gap is likely to occur between the heat transfer body and the back surface of the board, resulting in poor conduction. There are cases where the thermal function deteriorates and it is not possible to obtain the desired heat dissipation performance.
Japanese Patent Application Publication No. 2005-283563

Therefore, in order to solve the above problems, the present invention efficiently dissipates heat from the LED or the peripheral elements from the casing via the heat transfer body, even if the wiring board has peripheral elements such as resistive elements mounted on the back side. The aim is to make it possible to do so in a practical manner.

That is, the light irradiation device according to the present invention includes a wiring board having a width direction and a length direction, a plurality of LEDs arranged on the surface of the wiring board in one row or plural rows along the length direction, and A plurality of peripheral elements arranged in one or more rows along the length direction on the back surface of the wiring board, and a housing for accommodating the wiring board on which the LEDs and peripheral elements are mounted, and from the LEDs. The emitted light is emitted from a light emitting surface provided on the housing.

A housing groove extending in the length direction is formed on the inner surface of the bottom plate of the housing, and a deep bottom portion is formed in the widthwise center of the housing groove, and A shallow bottom part with a constant depth is formed on both sides of the bottom part, and the peripheral element mounted on the back side of the wiring board fits into the accommodation groove, and when viewed from the length direction. and is fixed on the inner surface of the housing bottom plate so as to span over the housing groove, and the housing groove includes a viscoelastic heat transfer body having a thickness that is the same as or slightly larger than the depth of the shallow bottom part. It is characterized by being inset.

With such a device, both sides of the wiring board in the width direction can be securely fixed to the lateral parts of the housing groove on the inner surface of the bottom plate, and both sides of the housing groove have a constant depth. A shallow bottom portion is provided, and since the front and back surfaces of the heat transfer body are not uneven in this portion, the heat transfer body is in close contact with the back surface of the wiring board and the bottom surface of the shallow bottom portion, and the heat of the LED is dissipated from this portion. can be efficiently transmitted to the bottom plate and released.

On the other hand, since a deep bottom part is formed in the center of the accommodation groove, the heat transfer body immediately below the peripheral element is recessed to some extent in advance, and the volume of the peripheral element protruding from the back surface of the wiring board is sufficiently absorbed. can. Therefore, it is possible to prevent the reaction force from causing distortion or bending of the wiring board, thereby preventing the irradiation direction of each LED from varying.

In order to more efficiently transmit the heat of the LED from the shallow bottom to the heat transfer body, the wiring board connects the wiring pattern layers provided on the front and back surfaces, and the wiring pattern layers on the front and back surfaces. A via penetrating in the thickness direction is preferably provided, and the via is preferably disposed on the shallow bottom portion when viewed from the length direction.

In order to increase the contact surface of the heat transfer body with the bottom surface of the accommodation groove and improve heat transfer efficiency, the side surface of the deep bottom part is inclined so that the width of the deep bottom part becomes smaller toward the bottom. Preferably.

If the depth dimension of the deep bottom part from the shallow bottom part is the same as or smaller than the thickness of the peripheral element, the heat transfer body is in close contact with both the resistance element and the bottom surface of the deep bottom part. Therefore, the heat generated in the resistive element can be reliably transferred to the bottom plate and efficiently radiated from there.

According to the present invention, even in the case of a wiring board in which peripheral elements such as resistive elements are mounted on the back surface, heat can be efficiently radiated from the LED or the peripheral elements from the casing via the heat transfer body. .

FIG. 1 is an overall perspective view showing a light irradiation device in an embodiment of the present invention. It is a figure which looked at the light irradiation device in the same embodiment from the width direction and the longitudinal direction. 3 is a cross-sectional view taken along line AA in FIG. 2 and a partially enlarged view thereof. FIG. It is a surface view of the wiring board in the same embodiment. It is a back view of the wiring board in the same embodiment. It is an enlarged partial surface view of the wiring board in the same embodiment. It is an enlarged partial back view of the wiring board in the same embodiment. It is a perspective view showing the light irradiation device in other embodiments of the present invention.

An embodiment of the present invention will be described below with reference to the drawings.

The light irradiation device 100 according to the present embodiment is a line illumination device or a line illumination device that irradiates a predetermined irradiation area of a workpiece with linear or strip-shaped light, for example, for the purpose of inspecting flaws on the surface of the workpiece. It is called a bar lighting device, and as shown in FIGS. 1 to 3, it includes a housing 1 in the shape of a long and narrow rectangular parallelepiped, and a wiring board 2 in the shape of a rectangular strip housed within the housing 1. It includes a plurality of LEDs 3 and a peripheral element 4 (resistance element 4 in this case) mounted on the wiring board 2.
Each part will be explained in detail below.

The housing 1 includes a bottom plate 11 and a pair of side plates 12 extending in the longitudinal direction and provided by metal extrusion molding or the like, and a pair of end plates 13 attached to both ends of the bottom plate 11 and the side plates 12 in the longitudinal direction. It is something that Further, in this housing 1, a light-transmitting plate 14 (or a diffusion plate) for emitting line-shaped light is provided on the surface facing the bottom plate 11.

Slot grooves into which slot nuts can be inserted are provided on the outer surfaces of the bottom plate 11 and side plates 12 so as to extend in the longitudinal direction, and the unevenness formed by the slot grooves also functions as a heat dissipation structure. has been done.

In the following, the direction perpendicular to the longitudinal direction of the housing 1 and connecting the side plates 12 will be referred to as the width direction, and the direction perpendicular to the longitudinal direction and connecting the bottom plate 11 and the transparent plate 14 will be referred to as the height direction or depth. It is called the direction.

As shown in FIG. 3, etc., the wiring board 2 includes an insulating layer 21, wiring pattern layers 22a and 22b, which are metal thin films formed on the front and back surfaces of the insulating layer 21, respectively, and the insulating layer 21 in the thickness direction. It has an elongated rectangular shape with a via 23 that penetrates through and connects the wiring pattern layers 22a and 22b on the front and back surfaces, and its length direction is the longitudinal direction of the casing 1, and the thickness direction is the above-mentioned one. They are accommodated in the casing 1 so as to match the height direction of the casing 1, respectively.

As shown in FIGS. 3, 4, and 6, the front wiring pattern layer 22a is provided over almost the entire surface of the insulating layer 21, and includes the LED connection pattern layer 22a1 to which the LED 3 is soldered, and the wiring. It is divided into a positive pattern layer 22a2 connected to a positive terminal (not shown) of the board 2 and a negative pattern layer 22a3 connected to a negative terminal (not shown) of the wiring board 2.

The LED connection pattern layer 22a1 is set at the center in the width direction of the wiring board 2, and extends substantially across both ends in the longitudinal direction. This LED connection pattern layer 22a1 is divided into an anode pattern P1, a cathode pattern P2, and a heat radiation pattern P3 to which the anode pad, cathode pad, and heat radiation pad of the LED 3 are connected by soldering, respectively.

The positive pattern layer 22a2 and the negative pattern layer 22a3 are respectively provided adjacent to both sides of the LED connection pattern layer 22a1 in the width direction, and, like the LED connection pattern layer 22a1, substantially span both longitudinal ends of the wiring board 2. It is stretched.

As shown in FIGS. 3, 5, and 7, the back side wiring pattern layer 22b extends directly behind the LED connection pattern layer 22a1, that is, at the center of the back surface of the insulating layer 21 in the width direction, and extends to both ends in the longitudinal direction. It is set to extend. The width thereof is slightly larger than that of the LED connection pattern layer 22a1, and is set to extend to the back side of the plus pattern layer 22a2 and the minus pattern layer 22a3. This back side wiring pattern layer 22b includes a back LED connection pattern layer 22b1 connected to the LED connection pattern layer 22a1 via vias 23, and vias (not shown) in each of the plus pattern layer 22a2 and the minus pattern layer 22a3. It is divided into a back positive pattern layer 22b2 and a back negative pattern layer 22b3 which are connected via. The back LED connection pattern layer 22b1 is divided into a back anode pattern Q1, a back cathode pattern Q2, and a back heat radiation pattern Q3, which are connected to the anode pattern P1, cathode pattern P2, and heat radiation pattern P3 via vias 23, respectively. There is.

Further, adjacent on both sides of the backside wiring pattern layer 22b in the width direction, the wiring pattern layer 22b is not provided, and the insulating layer 21 is an insulating region 22c exposed on the surface.
The via 23 is formed by metal plating the inner surface of a through hole that penetrates the wiring board 2 in the thickness direction, and here, as shown in FIG. 3, FIG. 6, and FIG. are placed on both sides of the Note that in FIG. 3, the vias 23 are drawn as solid for ease of understanding.

The LEDs 3 are of a surface mount type, and in this embodiment, as shown in FIGS. 4 and 6, a plurality of LEDs 3 are arranged in a straight line at equal intervals in the center of the surface width direction of the wiring board 2. It is equipped as follows. More specifically, as described above, the anode pad, cathode pad, and heat radiation pad (not shown) of each LED 3 are soldered to the anode pattern P1, cathode pattern P2, and heat radiation pattern P3 of the wiring board 2, respectively. There is.

The resistance elements 4 are of a chip type, and in this embodiment, as shown in FIGS. 5 and 7, a plurality of resistance elements 4 are arranged in a straight line in the center of the width direction of the wiring board 2. It is mounted by soldering.

When the wiring board 2 on which the LEDs 3 and the resistive elements 4 are mounted is viewed from the longitudinal direction, the LEDs 3 and the resistive elements 4 are arranged at the center in the width direction of the wiring board 2, as shown in FIG. It can be said that an element arrangement area A1 is set, and on both sides of this element arrangement area A1, via arrangement areas A2 in which vias 23 are arranged are set.

In this embodiment, the wiring board 2 is fixed onto the inner surface of the casing bottom plate 11 with screws or the like, with the LED 3 mounted on its surface facing the transparent plate 14. . In addition, in the figure, the reference numeral 25 attached to the wiring board 2 is a screw insertion hole for passing the screw.

Next, the fixing structure for fixing the wiring board 2 to the bottom plate 11 will be described in detail with reference to FIG. 3 and the like.

The inner surface of the bottom plate 11 has a rectangular shape in plan view, and its width and length are set to be slightly larger than the width and length of the wiring board 2, respectively. A housing groove 5 extending in the longitudinal direction is formed at the center in the width direction of the inner surface of the bottom plate, and a heat transfer body having a viscoelastic property with equal thickness and having a rectangular shape with equal thickness is formed in the housing groove 5. 6 is accommodated.

When viewed from the longitudinal direction, the wiring board 2 is fixed on the inner surface of the bottom plate 11 so as to span over the housing groove 5. The heat transfer body 6 is pressed between the bottom surface of the groove 5 and is configured to be in close contact with both.
This will be explained more specifically.

The width of this accommodation groove 5 is almost the same as the width of the heat transfer body 6, but when compared with the back side wiring pattern layer 22b, it seems to be the same or slightly larger than the width of the back side wiring pattern layer 22b. is set to . The back side wiring pattern layer 22b is entirely disposed on the opening of the accommodation groove 5, and on the flat surface of the inner surface of the bottom plate on both sides of the accommodation groove 5 (hereinafter referred to as the bottom plate flat part 11a). Only the insulating regions 22c formed on the back surface of both sides of the wiring board 2 come into contact with each other and are screwed.
The length of this accommodation groove 5 is approximately the same as the length of the heat transfer body 6, and extends to both longitudinal ends of the inner surface of the bottom plate.
The depth of the housing groove 5 is set such that it is shallow on both sides in the width direction and deep at the center.

The depth of the shallow bottom portion 51, which is a shallow portion of the housing groove 5, is set to a constant depth that is equal to or slightly smaller than the thickness of the heat transfer body 6. The via arrangement area 23 is set on this shallow bottom portion 51.

On the other hand, the deep bottom part 52 of the accommodation groove 5 has a groove shape that extends to both ends in the longitudinal direction, and its bottom surface is flat, and both sides thereof have a width dimension that decreases toward the bottom. is symmetrically inclined. That is, when viewed in cross section, the deep bottom portion 52 has a symmetrical downward trapezoidal shape. The bottom width of this deep bottom portion 52 is set to be larger than the width of the resistive element 4, and its depth (depth from the shallow bottom portion 51) is set to be the same as or slightly smaller than the height of the resistive element 4. The resistive element 4 is located directly above the bottom surface of the deep bottom portion 52 .

Therefore, when the wiring board 2 is screwed onto the bottom plate 11, both sides of the heat transfer body 6 in the width direction are located at the shallow bottom part 51, and the bottom surface of the shallow bottom part 51 and the back surface of the wiring board 2 are located at the shallow bottom part 51. It is tightly compressed by these. On the other hand, the center portion of the heat transfer body 6 in the width direction is pressed by the resistance element 4 mounted on the back surface of the wiring board 2, is depressed, and comes into close contact with the bottom surface of the deep bottom portion 52 of the housing groove 5.

Therefore, the heat generated by the LED 3 is mainly transmitted to the front side wiring pattern layer 22a, from there to the back side wiring pattern layer 22b directly below it through the vias 23, and further to the heat transfer body 6 located at the shallow bottom part 51 directly below it. It will be transmitted to the bottom plate 11 through the air and released.

At this time, since the shallow bottom portion 51 has a constant depth and the heat transfer body 6 of the same thickness is accommodated therein, the heat transfer body 6 is in close contact with the back surface of the wiring board 2 without any unevenness on its surface. At the same time, its back surface also comes into close contact with the bottom surface of the shallow bottom portion 51. Therefore, the heat of the LED 3 can be efficiently transmitted to the bottom plate 11 and released from there.

On the other hand, the heat generated by the resistance element 4 is mainly transmitted to the heat transfer body 6 located in the deep bottom part 52 directly below it, and from there to the bottom plate 11 and released. Also, in this part, the heat transfer body 6 is in close contact with both the resistance element 4 and the bottom surface of the deep bottom part 52, so that the heat generated in the resistance element 4 is efficiently transmitted to the bottom plate 11 and released from there. be able to.

Furthermore, the heat transfer body 6 directly below the resistance element 4 is recessed to some extent in advance by the deep bottom portion 52, and the volume of the protrusion of the resistance element 4 can be sufficiently absorbed. Excessive pressure will not cause distortion or bending of the wiring board 2 due to the reaction force, and the wiring board 2 will press the heat transfer body 6 with appropriate pressure, which is necessary for heat dissipation. This will allow you to maintain a good adhesion.
Note that the present invention is not limited to the above embodiments.

For example, in the embodiment, the light irradiation device 100 in which the LEDs 3 are arranged in a linear row (or in multiple rows) is taken as an example, but as shown in FIG. The present invention is also applicable to a ring-shaped light irradiation device 200 (shown in FIG. 8) arranged in a plurality of rows (or a plurality of rows) and a partial ring-type light irradiation device. In this case, the wiring board is annular or partially annular, and the circumferential direction thereof corresponds to the longitudinal direction or longitudinal direction in the above embodiment. Further, the radial direction corresponds to the width direction in the above embodiment.

Further, the present invention is not limited to a light irradiation device for inspection, but can also be applied to a light irradiation device for exposure.
In the embodiment described above, the side surfaces of the accommodation groove 5 are inclined so that the heat transfer body 6 comes in contact with a larger area in this portion to increase the heat transfer efficiency, but the side surface may be made vertical. . Further, although the bottom surface of the deep bottom portion 52 of the accommodation groove 5 is a flat surface in the above embodiment, it may be a concave surface or an uneven surface when viewed from the longitudinal direction.

Furthermore, insulating regions 22c were provided on both sides of the back surface of the wiring board 2 to prevent electrical connection even if they came into contact with the inner surface of the bottom plate 11. A sheet may be interposed or the inner surface of the bottom plate may be coated with insulation.

In addition, the present invention is not limited to the embodiments and modified examples described above, and various modifications can be made without departing from the spirit thereof, such as by appropriately combining each of these configurations.

100... Light irradiation device 1... Housing 14... Transparent plate (light exit surface)
2... Wiring board 21... Insulating layers 22a, 22b... Wiring pattern layer 23... Via 3... LED
4...Resistance element (peripheral element)
5... Accommodation groove 52... Deep bottom part 51... Shallow bottom part 6... Heat transfer body

Claims (4)

A wiring board having a width direction and a length direction, a plurality of LEDs arranged in one or more rows along the length direction on the front surface of the wiring board, and a plurality of LEDs arranged in the length direction on the back surface of the wiring board. , a plurality of peripheral elements arranged in one row or a plurality of rows along the line, and a housing that houses a wiring board on which the LED and peripheral elements are mounted, and the light emitted from the LED is provided in the housing. The light is emitted from a light exit surface that is
A housing groove extending in the length direction is formed on the inner surface of the bottom plate of the housing,
A deep bottom portion is formed in the widthwise central portion of the storage groove, and shallow bottom portions with a constant depth are formed on both sides of the deep bottom portion,
The wiring board is fixed on the inner surface of the casing bottom plate so that the peripheral element mounted on the back side of the wiring board fits into the accommodation groove and is spanned over the accommodation groove when viewed from the length direction. has been
A light irradiation device characterized in that a viscoelastic heat transfer body having a thickness equal to or greater than the depth of the shallow bottom portion is fitted into the accommodation groove. The wiring board includes wiring pattern layers provided on each of the front and back surfaces, and a via penetrating in the thickness direction that connects the wiring pattern layers on the front and back surfaces,
The light irradiation device according to claim 1, wherein the via is arranged on the shallow bottom portion when viewed from the length direction. 3. The light irradiation device according to claim 1, wherein a side surface of the deep bottom part is inclined so that the width of the deep bottom part becomes smaller toward the bottom. 4. The light irradiation device according to claim 1, wherein the depth of the deep portion from the shallow portion is equal to or smaller than the thickness of the peripheral element.