Line light irradiation device and LED mounting board

Abstract

To easily design a wiring pattern, improve heat radiation, and suppress unevenness of radiation illuminance, in a line light irradiation device having a plurality of LEDs with different luminous colors.SOLUTION: A line light irradiation device comprises: a metal substrate in which a plurality of LEDs with different luminous colors is mounted in a line manner on a mounting surface on which a wiring pattern is formed; and a resin substrate on which a drive circuit for driving the plurality of LEDs is mounted, which is overlappingly mounted on the mounting surface of the metal substrate, and extends along a line direction in which the plurality of LEDs is arranged.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a line light irradiation device that irradiates line-shaped light, and an LED mounting substrate for the line light irradiation device.

Background Art

[0002] As the above line light irradiation device, in order to enhance heat dissipation, there is one in which an LED is mounted on a metal substrate on which a wiring pattern is formed (see Patent Document 1).

[0003] By the way, in such a line light irradiation device, there are not only types in which only a single-color LED is mounted, but also types in which a plurality of color LEDs are mounted on the substrate. In this case, since the wiring patterns for supplying power to each LED are complicated and intertwined, it is difficult to design with a single-layer metal substrate. Therefore, in those that require such a complicated wiring pattern, a two-layer metal substrate may be used. The two-layer metal substrate is formed by laminating a resin substrate on which a first-layer wiring pattern is formed on a base metal substrate, and a second-layer wiring pattern is formed thereon. The LEDs are mounted linearly on the second-layer wiring pattern.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when a plurality of LEDs are mounted on the surface of the above-described two-layer metal substrate, although there is an advantage that the wiring pattern design is easier than when using a single-layer metal substrate, there is a problem that the heat dissipation property deteriorates. That is, when using a two-layer metal substrate, since a resin substrate with poor thermal conductivity is interposed between the LED that generates heat and the metal substrate having the main heat dissipation function, it becomes difficult for heat to be transmitted to the metal substrate.

[0006] Furthermore, the two-layer metal substrate is manufactured by bonding a metal substrate and a thin resin substrate by high-temperature pressing during its production. However, in this case, there is a problem that a large warp occurs in the entire metal substrate due to the difference in thermal expansion between the metal substrate and the resin substrate. In this situation, an air layer is formed between the back surface of the metal substrate and the bottom surface of the housing or the like to which it is attached, resulting in an increase in contact thermal resistance and further deterioration of heat dissipation performance. Also, if the amount of warp is too large, the resin substrate may peel off from the metal substrate, leading to a problem of reduced manufacturing yield.

[0007] In addition, due to the occurrence of a large warp in the metal substrate, significant unevenness in contact thermal resistance occurs in the line direction, and there is also a problem that the uniformity of irradiance in the line direction deteriorates due to variations in the output caused by the temperature characteristics of the LEDs. Furthermore, due to the unevenness in contact thermal resistance in the line direction, areas where the LEDs deteriorate quickly and areas where they do not occur, and in that sense, there is also a problem that the uniformity of irradiance in the line direction decreases when used for a long time.

[0008] The present invention has been made to solve the above problems all at once, and in a line light irradiation device having a plurality of LEDs with different emission colors, its main problems are to facilitate the design of the wiring pattern, improve heat dissipation performance, and suppress unevenness in irradiance.

Means for Solving the Problems

[0009] That is, the line light irradiation device and the LED mounting substrate of the present invention include a metal substrate on which a plurality of LEDs are mounted in a line on a mounting surface on which a wiring pattern is formed, and a drive circuit for driving the plurality of LEDs is mounted, and a resin substrate that is mounted so as to overlap the mounting surface of the metal substrate and extends along the line direction in which the plurality of LEDs are arranged.

Effects of the Invention

[0010] According to the present invention configured as described above, in a line light irradiation device having a plurality of LEDs with different emission colors, the wiring pattern can be easily designed, the heat dissipation can be improved, and the unevenness of the irradiance can be suppressed.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0012] Hereinafter, a line light irradiation device 200 according to an embodiment of the present invention will be described with reference to the drawings.

[0013] The line light irradiation device 200 of the present embodiment is for irradiating a line-shaped light on the inspection target surface of a workpiece. The line light irradiation device 200 of the present embodiment has a plurality of LEDs 3 of different colors mounted adjacent to each other in a line, and the plurality of LEDs 3 have emission colors such as red, green, blue, etc., and are, for example, surface-mounted types. As shown in FIGS. 1 to 6, this line light irradiation device 200 includes a box-shaped casing C having a rectangular (rectangular) bottom surface with one side open, and a plurality of LED mounting substrates 100 arranged and housed in the casing C.

[0014] As shown in FIGS. 2 to 5, the LED mounting substrate 100 includes a metal substrate 1 on which a plurality of LEDs 3 are mounted in a line, and a resin substrate 2 on which a drive circuit for driving the current applied to the plurality of LEDs 3 is mounted. With the resin substrate 2 mounted on the metal substrate 1, the plurality of mounted LEDs 3 and the drive circuit are electrically connected.

[0015] The metal substrate 1 has an insulating layer formed on the surface of a plate-shaped aluminum base material having a substantially rectangular shape in plan view, and a wiring pattern made of a copper foil is formed on the insulating layer. It is a so-called single-sided metal substrate 1. The area of the panel portion of this metal substrate 1 is larger than that of the resin substrate 2. As shown in FIGS. 2 and 3, the mounting surface constituted by the panel portion is divided into an LED mounting region where the surface-mounted LED 3 is mounted and a substrate mounting region where the resin substrate 2 is overlapped and mounted. In the present embodiment, two substrate mounting regions extending along the line direction are set so as to sandwich the LED mounting region extending along the line direction. Note that no components such as elements are mounted on the back surface (the surface opposite to the mounting surface) of the metal substrate 1, and it has a flat shape.

[0016] In the present embodiment, the LEDs 3 are mounted in a line in one row at equal pitches along the longitudinal direction on the mounting surface of the metal substrate 1. In the present embodiment, the LEDs 3 are mounted in a row so as to pass through the center in the width direction (short side direction) of the metal substrate 1. In the present embodiment, a plurality of types of LEDs 3 having different emission colors are mounted periodically (regularly) along the line direction (longitudinal direction). Here, three different-color LEDs 3 are mounted so as to be arranged in order. Some or all of the mounted LEDs 3 are provided with a heat dissipation pad that is thermally connected to the mounting surface on its bottom surface.

[0017] The resin substrate 2 is, for example, a multilayer substrate composed of two layers, and for example, an FR-2 substrate is used. Wiring patterns made of copper foil are formed on each layer of the resin substrate 2. The resin substrate 2 has a substantially rectangular shape (rectangular shape) in plan view, and is mounted on the substrate mounting area so that its longitudinal direction aligns with the longitudinal direction of the metal substrate 1 (i.e., the line direction). That is, this resin substrate 2 is mounted on the substrate mounting area so as to extend along the line direction. The length of the resin substrate 2 in the line direction is the same as the length of the metal substrate 1, and the length in the width direction is half or less of the length of the metal substrate 1. The resin substrate 2 and the metal substrate 1 are electrically connected using solder or the like.

[0018] In this embodiment, two resin substrates 2 are mounted so as to sandwich a plurality of LEDs 3 mounted in a line. These two resin substrates 2 are mounted so as to form a pair with the plurality of LEDs 3 sandwiched therebetween.

[0019] In the LED mounting substrate 100 formed in this way, notches 4 are provided on a pair of sides extending along the line direction. These notches 4 are provided so as to notch both the metal substrate 1 and the resin substrate 2. That is, notches 4 are provided on the respective sides of the metal substrate 1 and the resin substrate 2 so as to overlap each other. These notches 4 have a shape extending along the line direction.

[0020] In the line light irradiation device 200 of this embodiment, the plurality of LED mounting substrates 100 are fixedly attached to the bottom plate of the casing C so as to be arranged along the line direction. Specifically, each LED mounting substrate 100 is formed with screw insertion holes 5 penetrating in the thickness direction, and is fixed to the bottom plate of the casing C by screwing with screws passed through the screw insertion holes 5. The screw insertion holes 5 are formed by through holes penetrating both the resin substrate 2 and the metal substrate 1. As shown in FIG. 4, the diameter of the through hole formed in the resin substrate 2 is larger than that of the through hole formed in the metal substrate 1, and the tightening force of the inserted screw is loaded only on the metal substrate 1. By doing so, the load on the solder connecting the resin substrate 2 and the metal substrate 1 can be reduced, and the back surface of the metal substrate 1 can be firmly attached to the bottom plate of the casing C or the like to reduce the contact thermal resistance.

[0021] In each LED mounting substrate 100, a plurality of screw insertion holes 5 are formed along the line direction. When the resin substrate 2 is viewed in plan, each screw insertion hole 5 is formed at a position closer to the LED 3 in the width direction. That is, the screw insertion hole 5 is formed on the LED 3 side of the center line passing through the center of the width direction of the resin substrate 2.

[0022] The back surface of the fixed LED mounting substrate 100 (that is, the back surface of the metal substrate 1) is in surface contact with the heat dissipation member provided in the casing C. More specifically, in the back surface of the metal substrate 1, at least the region on the back side of the heat dissipation pad provided in the LED 3 is in surface contact with the heat dissipation member of the casing C. This heat dissipation member may be, for example, a heat dissipation fin or the bottom plate of the casing C.

[0023] According to the line light irradiation device 200 of this embodiment configured as described above, since the resin substrate 2 on which the drive circuit is mounted is stacked on the mounting surface of the metal substrate 1 on which the wiring pattern is formed, the wiring patterns for driving the plurality of color LEDs 3 can be configured in multiple layers. Therefore, a large number of wiring patterns do not get mixed up in the same layer, and the design can be facilitated.

[0024] In addition, since the LED 3 is directly mounted on the metal substrate 1 without intervening the resin substrate 2 with low thermal conductivity, the heat generated from the LED 3 can be efficiently transferred to the metal substrate 1 and dissipated.

[0025] Furthermore, the resin substrate 2 is not overlaid on the entire surface of the metal substrate 1, but is partially overlaid and mounted except for the region where the LED 3 is mounted. Therefore, compared with a two-layer metal substrate in which the resin substrate is bonded to almost the entire surface of the metal substrate, warping of the metal substrate 1 during manufacturing can be suppressed. For this reason, the gap generated between the back surface of the metal substrate 1 and its mounting surface can be reduced, an increase in contact thermal resistance can be suppressed, and heat dissipation performance can be improved.

[0026] In addition, by suppressing warping of the metal substrate 1, generation of unevenness in contact thermal resistance can also be suppressed, and a decrease in the uniformity of the irradiance of the LED 3 due to variations in output depending on temperature characteristics and variations in the degree of deterioration progress can be suppressed.

[0027] Note that the present invention is not limited to the above-described embodiment. For example, the line light irradiation device 200 of the above-described embodiment has three types of LEDs 3 with different emission colors mounted thereon, but is not limited thereto. The line light irradiation device 200 of other embodiments is not limited to three types of LEDs 3 to be mounted, and may be two types or four or more types. In addition, the plurality of types of LEDs 3 mounted periodically in a line may have the same number of mountings in one cycle or may be different. Further, the LED 3 may be of a type in which a plurality of LED chips or LED chips of a plurality of colors are mounted in one package.

[0028] Furthermore, in the line light irradiation device 200 of the above-described embodiment, the resin substrates 2 are mounted on both sides sandwiching the plurality of LEDs 3 mounted in a line, but is not limited thereto. In other embodiments, the resin substrate 2 may be mounted on only one side with respect to the plurality of LEDs 3 mounted in a line.

[0029] In the above embodiment, the plurality of LEDs 3 were mounted in a line in a single row, but it is not limited to this. In other embodiments, the plurality of LEDs 3 may be mounted in a line in a plurality of rows (for example, two rows). Further, in the above embodiment, the plurality of LEDs 3 were mounted in a line at an equal pitch, but it is not limited to this. In other embodiments, some or all of the plurality of LEDs 3 may be mounted at different pitches.

[0030] In addition, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit thereof. For example, the light irradiation device of the present invention includes the following aspects.

[0031] (Aspect 1) A metal substrate on which a plurality of LEDs having different emission colors are mounted in a line on a mounting surface on which a wiring pattern is formed, and a resin substrate mounted so as to overlap the mounting surface of the metal substrate and extending along the line direction in which the plurality of LEDs are arranged. A line light irradiation device comprising:

[0032] In such an aspect, since the resin substrate on which the drive circuit is mounted is overlapped and mounted on the mounting surface of the metal substrate on which the wiring pattern is formed, a wiring pattern for driving a plurality of color LEDs can be configured in multiple layers. For this reason, a large number of wiring patterns do not get mixed up in the same layer, and the design can be facilitated. In addition, since the LED is directly mounted on the metal substrate without intervening a resin substrate having a low thermal conductivity, heat generated from the LED can be efficiently transmitted to the metal substrate and dissipated. Furthermore, since the resin substrate is not overlapped on the entire surface of the metal substrate, but is partially overlapped and mounted except for the region where the LED is mounted, compared to a two-layer metal substrate in which the resin substrate is bonded to almost the entire surface of the metal substrate, warping of the metal substrate during manufacturing can be suppressed. For this reason, the gap generated between the back surface of the metal substrate and its mounting surface can be reduced, an increase in contact thermal resistance can be suppressed, and heat dissipation performance can be improved. Moreover, by suppressing the warping of the metal substrate, the generation of uneven contact thermal resistance can also be suppressed, and the decrease in the uniformity of the irradiance of the LED due to the variation in output according to the temperature characteristics and the variation in the degree of deterioration progress can be suppressed.

[0033] (Aspect 2) The line light irradiation device according to Aspect 1, wherein the resin substrate is a multilayer substrate. In such an aspect, wiring patterns of three or more layers including the wiring pattern of the metal substrate can be drawn, and the degree of freedom in circuit design can be improved in a limited substrate area. Therefore, even if the types of LEDs increase and the wiring pattern becomes complicated, it is possible to draw a desired electric circuit.

[0034] (Aspect 3) The line light irradiation device according to Aspect 1 or 2, wherein the resin substrate is mounted on both sides with the plurality of line-shaped LEDs interposed therebetween. In this way, the degree of freedom in circuit design can be further improved as compared with the case where the resin substrate is mounted only on one side.

[0035] (Aspect 4) In the line light irradiation device according to any one of Aspects 1 to 3, some or all of the plurality of LEDs are provided with heat dissipation pads on their bottom surfaces that are thermally connected to the mounting surface, and the region on the back side of the heat dissipation pads on the back surface of the metal substrate is in surface contact with a heat dissipation member. In this way, heat can be efficiently dissipated from the back surface of the metal substrate generated by the LED.

[0036] (Aspect 5) In the metal substrate and the resin substrate, a plurality of screw insertion holes penetrating in the thickness direction are formed along the line direction, and when the resin substrate is viewed in plan, each screw insertion hole is formed at a position closer to the LED in the width direction orthogonal to the line direction. The line light irradiation device according to any one of Aspects 1 to 4. By doing so, the area near the LED on the back surface of the metal substrate can be brought into close contact with the mounting surface such as the bottom surface of the housing, reducing the contact thermal resistance and improving the heat dissipation performance. Also, the variation in the contact thermal resistance in the line direction can be reduced, so the unevenness of the irradiance can be reduced.

[0037] (Aspect 6) The line light irradiation device according to any one of Aspects 1 to 5, wherein notches overlapping each other are provided on one side extending in the line direction of each of the metal substrate and the resin substrate. In such an aspect, the contact area between the metal substrate and the resin substrate can be reduced, and the warping can be further reduced. Furthermore, through this notch, for example, wiring connecting the upper wiring pattern and the lower wiring pattern can be drawn.

[0038] (Aspect 7) An LED mounting substrate including a metal substrate on which a plurality of LEDs having different emission colors are mounted in a line on a mounting surface on which a wiring pattern is formed, and a resin substrate mounted so as to overlap the mounting surface of the metal substrate and extending along the line direction in which the plurality of LEDs are arranged, and a drive circuit for driving the plurality of LEDs is mounted on the resin substrate. With such an LED mounting substrate, the same operational effects as those of the above-described line light irradiation device can be achieved.

Explanation of Reference Numerals

[0039] 200 ··· Line light irradiation device 100 ··· LED mounting substrate 1 ··· Metal substrate 2 ··· Resin substrate 3 ··· LED C ··· Casing

Claims

1. A metal substrate on which a plurality of LEDs having different emission colors are mounted in a line on a mounting surface on which a wiring pattern is formed, A line light irradiation device comprising: a resin substrate that is mounted so as to overlap the mounting surface of the metal substrate and extends along the line direction in which the plurality of LEDs are arranged, and a drive circuit that drives the plurality of LEDs is mounted on the resin substrate.

2. The line light irradiation device according to claim 1, wherein the resin substrate is a multilayer substrate.

3. The line light irradiation device according to claim 1, wherein the resin substrate is mounted on both sides of the plurality of line-shaped LEDs.

4. Some or all of the plurality of LEDs are provided with a heat dissipation pad on their bottom surfaces that is thermally connected to the mounting surface, The line light irradiation device according to claim 1, wherein a region on the back side of the heat dissipation pad on the back surface of the metal substrate is in surface contact with a heat dissipation member.

5. A plurality of screw insertion holes penetrating in the thickness direction are formed in the metal substrate and the resin substrate along the line direction, When the resin substrate is viewed in plan, each of the screw insertion holes is formed at a position closer to the LED in the width direction orthogonal to the line direction. The line light irradiation device according to claim 1.

6. The line light irradiation device according to claim 1, wherein notches overlapping each other are provided on one side of each of the metal substrate and the resin substrate extending in the line direction.

7. A metal substrate on which a plurality of LEDs having different emission colors are mounted in a line on a mounting surface on which a wiring pattern is formed, An LED mounting substrate comprising: a resin substrate that is mounted so as to overlap the mounting surface of the metal substrate and extends along the line direction in which the plurality of LEDs are arranged, and a drive circuit that drives the plurality of LEDs is mounted on the resin substrate.

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