Circuit board fixing structure and light irradiation device including the same

Abstract

To provide a circuit board fixing structure capable of ensuring electrical insulation between a fixing screw and a base.SOLUTION: A circuit board fixing structure for fixing a circuit board to a surface of a base includes a wiring pattern formed on the surface of the circuit board, a first through hole penetrating from the surface to the back surface of the circuit board, a second through hole penetrating from the surface to the back surface of the base so as to communicate with the first through hole, a metal fixing screw inserted from the first through hole to the second through hole, and a nut member screwed with the fixing screw. The nut member includes a metal nut body screwed with the fixing screw and an insulating member that houses the nut body, and when the fixing screw and the nut body are fastened, the nut member is housed and fixed in the second through hole, and the fixing screw and the nut body are electrically insulated from the base.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a circuit board fixing structure that uses a fixing member to fix a circuit board onto a base (e.g., a heat sink, a base plate), and in particular to a circuit board fixing structure that fixes the circuit board while ensuring electrical insulation between the fixing member and the base, and a light irradiation device equipped with the same. [Background technology]

[0002] Conventionally, ultraviolet-curable inks that are cured by irradiation with ultraviolet light have been used as printing inks. Also, ultraviolet-curable resins are used as sealants for FPDs (Flat Panel Displays) such as liquid crystal panels and organic EL (Electro Luminescence) panels. To cure such ultraviolet-curable inks and ultraviolet-curable resins, a light irradiation device that irradiates ultraviolet light is generally used (for example, Patent Document 1).

[0003] The light irradiation device described in Patent Document 1 includes a light-emitting unit having many ultraviolet LED elements arranged on a substrate, a heat sink arranged in close contact with the substrate of the light-emitting unit to conduct heat from the light-emitting unit, and a water-cooling block to discharge heat from the heat sink to the outside. The light-emitting unit includes a fixing screw for fixing the substrate to the heat sink, a power supply terminal for supplying power to the light-emitting unit, an insulating bush covering the outer periphery of part of the shaft of the fixing screw, a washer, etc., and the power supply terminal is fastened together with the fixing screw to supply power to the light-emitting unit and to fix the light-emitting unit to the heat sink. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-091975 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the light irradiation device described in Patent Document 1, since the fixing screw serves both to supply power and to fix the light-emitting unit (i.e., the fixing screw also fastens the power supply terminal), an insulating bush is provided on the outer periphery of the shaft of the fixing screw to ensure electrical insulation between the heat sink and the power supply terminal (and the light-emitting unit) to prevent a short circuit between the heat sink and the power supply terminal (and the light-emitting unit). However, since insulating bushings are usually made of resin, if the insulating bushing is exposed in the space above the substrate of the light-emitting section (i.e., the side where the LED element is placed) as in the configuration of Patent Document 1, it will be exposed to ultraviolet light from the LED element, causing photodegradation or damage due to high temperatures. Furthermore, in the configuration of Patent Document 1, the power supply terminal, insulating bushing, and washer are sandwiched between the head of the fixing screw and the substrate, which causes the head of the fixing screw to protrude significantly from the substrate surface and be hit by the ultraviolet light emitted from the LED element, which can cause problems such as a reduction in the efficiency of extracting ultraviolet light from the light irradiation device.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a circuit board fixing structure capable of ensuring electrical insulation between a fixing screw and a base (e.g., a heat sink, etc.) without using an insulating bush exposed in the space above the board, and also to provide a light irradiation device equipped with such a circuit board fixing structure. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the circuit board fixing structure of the present invention is a circuit board fixing structure for fixing a circuit board to the surface of a base, and comprises a wiring pattern formed on the surface of the circuit board, a first through hole penetrating from the surface to the back surface of the circuit board, a second through hole penetrating from the surface to the back surface of the base so as to communicate with the first through hole, a metal fixing screw inserted from the first through hole to the second through hole, and a nut member screwed into the fixing screw, wherein the nut member comprises a metal nut body screwed into the fixing screw and an insulating member that houses the nut body, and when the fixing screw and the nut body are fastened, the nut member is housed and fixed in the second through hole, and the fixing screw and the nut body are electrically insulated from the base.

[0008] With this configuration, when the fixing screw and the nut body are tightened, the nut member having the insulating member is accommodated in the second through hole and fixed, and the fixing screw and the nut body are electrically insulated from the base, thereby ensuring electrical insulation between the fixing screw and the base.

[0009] It is also preferable that when the fixing screw and the nut body are fastened, the fixing screw and the wiring pattern are electrically connected to each other.

[0010] Furthermore, it is desirable that the nut body has a cylindrical or polygonal columnar shape, and that the insulating member has a first portion covering the outer peripheral surface of the nut body and a second portion covering the surface of the nut body facing the first through hole.

[0011] The second through hole is preferably a stepped hole in which the first inner diameter on the front side of the base is smaller than the second inner diameter on the back side. In this case, it is preferable that the shaft diameter of the fixing screw is smaller than the first inner diameter, and the outer diameter of the nut member is larger than the first inner diameter and slightly smaller than the second inner diameter.

[0012] It is also desirable that there are multiple fixing screws and nut members, and that at least one of the fixing screws is connected to a positive terminal that supplies power to the circuit board, and that at least one of the fixing screws is connected to a negative terminal through which a return current of the circuit board flows.

[0013] In addition, it is preferable that the base is a heat sink that cools the circuit board.

[0014] From another viewpoint, the light irradiation device of the present invention is characterized by comprising any one of the circuit board fixing structures described above and a plurality of light emitting elements arranged on the circuit board. In this case, it is preferable that the light emitted from the light emitting elements is light having a wavelength in the ultraviolet range. Effect of the Invention

[0015] As described above, according to the present invention, a circuit board fixing structure capable of ensuring electrical insulation between a fixing screw and a base (such as a heat sink) without using an insulating bush exposed in the space above the board as in the conventional art is realized. Also, a light irradiation device equipped with such a circuit board fixing structure is realized. [Brief description of the drawings]

[0016] [Figure 1] 1 is a front view illustrating a schematic configuration of a light irradiation device including a circuit board fixing structure according to an embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view illustrating a configuration of a circuit board fixing structure according to an embodiment of the present invention. [Diagram 3] 1 is an enlarged cross-sectional view illustrating a configuration of a circuit board fixing structure according to an embodiment of the present invention. [Figure 4] 1 is an exploded perspective view illustrating a schematic configuration of a light irradiation device including a circuit board fixing structure according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0018] Fig. 1 is a front view illustrating a schematic configuration of a light irradiation device 1 including a circuit board fixing structure 10 according to an embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line XX in Fig. 1. Fig. 3 is an enlarged view of part A in Fig. 2. Fig. 4 is an exploded perspective view of the light irradiation device 1 according to this embodiment.

[0019] The light irradiation device 1 of this embodiment is a light source device that is mounted on a printing device or the like and cures ultraviolet curable ink or ultraviolet curable resin. For example, the light irradiation device 1 is disposed above the irradiation object so that the front surface (the surface on which the light source module 110 is disposed) faces the irradiation object, and emits ultraviolet light downward toward the irradiation object. In this specification, as shown in FIG. 1, the direction in which the LED element 114 described later emits ultraviolet light is defined as the Z-axis direction, the longitudinal direction of the light irradiation device 1 (i.e., the left-right direction in FIG. 1) is defined as the X-axis direction, and the direction perpendicular to the Z-axis direction and the X-axis direction (i.e., the up-down direction in FIG. 1) is defined as the Y-axis direction. In addition, while ultraviolet light is generally defined as light having a wavelength of 400 nm or less, in this specification, ultraviolet light is defined as light having a wavelength (e.g., a wavelength of 250 to 420 nm) that can cure ultraviolet curable ink.

[0020] As shown in FIG. 1, the light irradiation device 1 of this embodiment includes a light source module 110, a heat sink 120 (base), an anode terminal 117 that supplies power to the light source module 110, a cathode terminal 118, etc., and a metal box-shaped case (not shown) that houses these.

[0021] The light source module 110 includes a rectangular LED substrate 112 on which a plurality of wiring patterns 112a to 112e are formed, and a plurality of LED elements 114 (light-emitting elements) arranged on the LED substrate 112. As shown in Fig. 1, the LED substrate 112 of this embodiment includes six through holes 113 (first through holes) penetrating from the front surface to the back surface of the LED substrate 112 (Figs. 2 to 4), and is fixed to a heat sink 120 by six metal fixing screws 116 inserted into the six through holes 113. Note that, as the LED substrate 112, it is preferable to use a ceramic substrate or the like formed of aluminum nitride having high thermal conductivity. In this embodiment, thermal grease (not shown) is applied to the surface of the heat sink 120 (the mounting surface of the light source module 110) and then the LED substrate 112 is placed on the heat sink 120, so that the thermal grease is sandwiched between the back surface of the LED substrate 112 and the heat sink 120, thereby improving the adhesion between the LED substrate 112 and the heat sink 120.

[0022] The LED elements 114 are, for example, LED chips that emit ultraviolet light, and in this embodiment, three LED elements 114 are arranged on each of the wiring patterns 112a to 112d, that is, four LED elements (X-axis direction) by three LED elements (Y-axis direction) in total, at predetermined intervals in the X-axis direction and the Y-axis direction. The anode terminal of each LED element 114 is die-bonded to the wiring pattern 112a to 112d directly below, and the cathode terminal is electrically connected to each of the adjacent wiring patterns 112b to 112e by the bonding wire 115. That is, in this embodiment, three LED elements 114 arranged in the Y-axis direction on each of the wiring patterns 112a to 112d are electrically connected in parallel, and the wiring patterns 112a to 112e are electrically connected in series by the bonding wire 115. An anode terminal 117 (positive terminal) is fastened to the wiring pattern 112a by a fixing screw , and a cathode terminal 118 (negative terminal) is fastened to the wiring pattern 112e by a fixing screw .

[0023] The anode terminal 117 and the cathode terminal 118 are electrically connected to a control circuit board (not shown), so that a drive current generated by the control circuit board is supplied to the LED elements 114 of the light source module 110. Specifically, when a drive current (i.e., an anode current) is supplied from the control circuit board to the anode terminal 117 connected to the wiring pattern 112a, the drive current flows through all the LED elements 114 arranged on the wiring patterns 112a to 112d, and each LED element 114 emits ultraviolet light of an amount of light according to the drive current. Note that each LED element 114 in this embodiment has substantially the same electrical characteristics, and is configured to emit ultraviolet light of substantially the same irradiation intensity distribution. The drive current flowing through each LED element 114 passes through the wiring pattern 112e, and a return current (i.e., a cathode current) is returned from the cathode terminal 118 connected to the wiring pattern 112e to the control circuit board.

[0024] In this way, when a drive current flows through all the LED elements 114 mounted on the light source module 110 and ultraviolet light is emitted from each LED element 114, the temperature rises due to self-heating of the LED elements 114, causing a problem of a significant drop in light emission efficiency. For this reason, in this embodiment, a heat sink 120 is provided in close contact with the light source module 110, and the heat generated by the LED elements 114 is forcibly dissipated.

[0025] The heat sink 120 is a member for fixing the light source module 110 and dissipating heat generated by the light source module 110, and is made of a metal having high thermal conductivity, such as copper or aluminum. As shown in Figs. 1 and 2, the heat sink 120 is a rectangular flat plate-shaped member, and the front surface (the surface on the positive side in the Z-axis direction) of the heat sink 120 is a mounting surface for the light source module 110. As shown in Figs. 2 to 4, the heat sink 120 has six through holes 126 (second through holes) that penetrate from the front surface to the back surface so as to communicate with the six through holes 113 formed in the LED substrate 112, and each through hole 126 is adapted to accommodate a nut member 130 that screws into each fixing screw 116.

[0026] 1 and 4, a supply port 122 and an outlet 124 for a coolant are provided on an end face of the heat sink 120 in the Y-axis direction. As shown in Fig. 2 and 3, a cylindrical flow path 121 through which the coolant flows is formed inside the heat sink 120 from the supply port 122 to the outlet 124. The coolant used is water, ethylene glycol, propylene glycol, or a mixture of these with water.

[0027] (Details of circuit board fixing structure 10) As described above, the LED substrate 112 of this embodiment is fixed to the surface (mounting surface) of the heat sink 120 by fixing screws 116 inserted through six through holes 113 (first through holes) formed in the LED substrate 112 and six through holes 126 (second through holes) formed in the heat sink 120, and nut members 130 screwed into each fixing screw 116 (FIG. 3). In other words, the circuit board fixing structure 10 of this embodiment is composed of a through hole 113 (first through hole) in the LED board 112, a through hole 126 (second through hole) in the heat sink 120, a fixing screw 116, and a nut member 130. The characteristic features of the circuit board fixing structure 10 of the present invention will be described in further detail below.

[0028] 3, the through hole 126 of the heat sink 120 is a stepped hole in which the inner diameter (first inner diameter) on the front side of the heat sink 120 is smaller than the inner diameter (second inner diameter) on the back side, and a step portion 126a is formed inside the through hole 126 to divide the through hole 126 into a first space 126b having a smaller inner diameter and a second space 126c having a larger inner diameter. The inner diameters of the first space 126b and the second space 126c are sufficiently larger than the shaft diameter of the fixing screw 116.

[0029] As shown in FIGS. 3 and 4, the nut member 130 includes a metal nut body 131 that screws into the fixing screw 116, and a resin insulating member 132 that houses the nut body 131.

[0030] The nut body 131 has a cylindrical or polygonal prism shape, and a screw hole 131 a is adapted to be screwed onto the shaft portion of the fixing screw 116 .

[0031] The insulating member 132 has a cylindrical shape and includes a first portion 132a covering the outer periphery of the nut body 131 and a second portion 132b covering the end face in the Z-axis direction (the end face on the through hole 113 side) of the nut body 131, and a through hole 132c through which the fixing screw 116 passes (i.e., slightly larger than the shaft diameter of the fixing screw 116) is formed in the second portion 132b. Note that the resin material of the insulating member 132 is preferably a material having excellent heat resistance, light resistance, and mechanical strength, such as fluororesin or PEEK resin.

[0032] The outer diameter of the nut member 130 (that is, the outer diameter of the insulating member 132) is larger than the inner diameter of the first space 126b of the through hole 126 and slightly smaller than the inner diameter of the second space 126c of the through hole 126.

[0033] In order to fix the LED substrate 112 of this embodiment to the heat sink 120, first, as shown in FIG. 4, the light source module 110 is placed on the surface of the heat sink 120, and fixing screws 116 are inserted into the six through holes 113 formed in the LED substrate 112 from the positive side in the Z-axis direction. Next, the insulating member 132 and the nut body 131 are inserted in this order into each through hole 126 of the heat sink 120 from the negative side in the Z axis direction, and each fixing screw 116 and each nut body 131 are fastened. Then, when each fixing screw 116 and each nut body 131 are tightened, the nut body 131 is accommodated in the insulating member 132, the nut member 130 (i.e., the nut body 131 and the insulating member 132) is accommodated in the second space 126c of the through hole 126, and the second portion 132b of the insulating member 132 abuts against the step portion 126a of the through hole 126 and is fixed (Figure 3). In other words, when each fixing screw 116 and each nut body 131 are tightened, the LED board 112 and the insulating member 132 are sandwiched between the head of each fixing screw 116 and each nut body 131, and the LED board 112 is fixed onto the heat sink 120 by the fastening force (compression force) of each fixing screw 116 and each nut body 131.

[0034] In this embodiment, as shown in FIG. 1, when each fixing screw 116 and each nut body 131 are fastened, the head of each fixing screw 116 is electrically connected to the adjacent (i.e., directly below) wiring pattern 112a, 112c, or 112d. In this embodiment, the anode terminal 117 (positive terminal) is fastened together onto the wiring pattern 112a, and the cathode terminal 118 (negative terminal) is fastened together onto the wiring pattern 112e by the fixing screw 116, so that power is supplied to the light source module 110 by the fixing screw 116. That is, in this embodiment, the fixing screw 116 serves both to fix the LED substrate 112 and to supply power. In this manner, when the fixing screws 116 of this embodiment are electrically connected to the adjacent wiring patterns 112a, 112c, or 112d, each fixing screw 116 has a predetermined electric potential. However, as described above, since the insulating member 132 is disposed between each fixing screw 116 and the heat sink 120 (FIG. 3), there is no direct contact with the heat sink 120 (i.e., electrical insulation is ensured between each fixing screw 116 and the heat sink 120).

[0035] In this manner, the circuit board fixing structure 10 of this embodiment is composed of the through hole 113 (first through hole) in the LED board 112, the through hole 126 (second through hole) in the heat sink 120, the fixing screw 116, and the nut member 130, and the LED board 112 is fixed onto the heat sink 120 by fastening the fixing screw 116 and the nut body 131. Furthermore, when each fixing screw 116 and each nut body 131 are tightened, each nut body 131 is contained in the through hole 126 and fixed, so the resin insulating member 132 is not exposed on the LED substrate 112, and there is no light degradation or damage due to high temperatures, as with conventional insulating bushings.

[0036] Furthermore, compared to a configuration using a conventional insulating bush, the amount of protrusion of the head of the fixing screw 116 from the surface of the LED substrate 112 can be kept low, so that even for components of ultraviolet light emitted from the LED element 114 with a large spread angle, as shown by the dashed arrow in Figure 3, no vignetting occurs, and it is possible to extract the desired amount of ultraviolet light.

[0037] Although the present embodiment has been described above, the present invention is not limited to the above configuration, and various modifications are possible within the scope of the technical concept of the present invention.

[0038] For example, in this embodiment, the light irradiation device 1 has been described as being equipped with the circuit board fixing structure 10, but the use of the circuit board fixing structure 10 is not limited to this, and it can be applied to an apparatus having a configuration for supporting a circuit board on a base (e.g., a heat sink, a base plate).

[0039] Further, the heat sink 120 in this embodiment has been described as a water-cooled heat sink, but is not necessarily limited to this configuration, and an air-cooled type or natural heat dissipation type heat sink can also be applied.

[0040] In addition, in this embodiment, the fixing screw 116 is inserted from the LED substrate 112 side (positive side in the Z-axis direction), and the nut body 131 is inserted from the negative side in the Z-axis direction into each through-hole 126 of the heat sink 120. However, the fixing screw 116 and the nut body 131 may be arranged in reverse. In that case, the head of the fixing screw 116 is housed in the insulating member 132.

[0041] In addition, in this embodiment, the nut body 131 has been described as having a cylindrical shape, and the insulating member 132 has a cylindrical shape. However, with such a configuration, there is a problem that the nut body 131 and / or the insulating member 132 may rotate when attaching the fixing screw 116, so the nut body 131 and / or the insulating member 132 may be provided with a rotation prevention function.

[0042] In addition, in this embodiment, the LED substrate 112 is fixed to the heat sink 120 using six fixing screws 116 and six nut members 130, but the number and arrangement of the fixing screws 116 and nut members 130 can be changed as appropriate depending on the size of the LED substrate 112, etc.

[0043] In addition, in this embodiment, the anode terminal 117 (positive terminal) is fastened together onto the wiring pattern 112a, and the cathode terminal 118 (negative terminal) is fastened together onto the wiring pattern 112e by the fixing screws 116. However, the wiring pattern in which the anode terminal 117 and the cathode terminal 118 are fastened together can be changed appropriately depending on the layout and circuit configuration of the wiring pattern. It is sufficient that the anode terminal 117 that supplies power to the LED board 112 is connected to at least one of the fixing screws 116, and the cathode terminal 118 through which the return current of the LED board 112 flows is connected to at least one of the fixing screws 116.

[0044] In addition, in this embodiment, when each fixing screw 116 and each nut body 131 are fastened, the head of each fixing screw 116 is electrically connected to the adjacent (i.e., directly below) wiring pattern 112a, 112c, or 112d, but this is not necessarily limited to such a configuration, and the head of each fixing screw 116 may be electrically insulated from the adjacent (i.e., directly below) wiring patterns 112a to 112e.

[0045] Furthermore, the light irradiation device 1 of this embodiment has been described as emitting ultraviolet light, but is not limited to such a configuration, and the present invention can also be applied to a light source device that emits visible light or infrared light.

[0046] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0047] 1:Light irradiation device 10: Circuit board fixing structure 110: Light source module 112: LED board 112a: Wiring pattern 112b: Wiring pattern 112c: Wiring pattern 112d: Wiring pattern 112e: Wiring pattern 113: Through hole 114: LED element 115: Bonding wire 116: Fixing screw 117: Anode terminal 118: Cathode terminal 120: Heat sink 121: Flow path 122: Supply port 124: Outlet 126: Through hole 126a: Step 126b: 1st space 126c: 2nd space 130: Nut material 131: Nut body 131a: Screw hole 132: Insulating material 132a :1st part 132b :Second part 132c: Through hole

Claims

1. A circuit board fixing structure for fixing a circuit board to a surface of a base, A wiring pattern formed on a surface of the circuit board; a first through hole penetrating from a front surface to a back surface of the circuit board; a second through hole penetrating from the front surface to the back surface of the base so as to communicate with the first through hole; a metal fixing screw inserted from the first through hole to the second through hole; A nut member that is screwed onto the fixing screw; Equipped with The nut member includes a metal nut body that is screwed onto the fixing screw, and an insulating member that houses the nut body. When the fixing screw and the nut body are fastened together, the nut member is accommodated in the second through hole and fixed, and the fixing screw and the nut body are electrically insulated from the base. A circuit board fixing structure comprising:

2. 2. The circuit board fixing structure according to claim 1, wherein the fixing screw and the wiring pattern are electrically connected when the fixing screw and the nut body are fastened together.

3. The nut body has a cylindrical or polygonal prism shape, The circuit board fixing structure according to claim 1, characterized in that the insulating member has a first portion covering an outer peripheral surface of the nut body and a second portion covering a surface of the nut body facing the first through hole.

4. 2. The circuit board fixing structure according to claim 1, wherein the second through hole is a stepped hole having a first inner diameter on the front side of the base which is smaller than a second inner diameter on the back side of the base.

5. The shaft diameter of the fixing screw is smaller than the first inner diameter, 5. The circuit board fixing structure according to claim 4, wherein an outer diameter of the nut member is larger than the first inner diameter and slightly smaller than the second inner diameter.

6. The fixing screw and the nut member are provided in a plurality of positions, A positive terminal for supplying power to the circuit board is connected to at least one of the fixing screws, and a negative terminal through which a return current of the circuit board flows is connected to at least one of the fixing screws.

2. The circuit board fixing structure according to claim 1.

7. 2. The circuit board fixing structure according to claim 1, wherein the base is a heat sink for cooling the circuit board.

8. The circuit board fixing structure according to any one of claims 1 to 7, A plurality of light emitting elements disposed on the circuit board; A light irradiation device comprising:

9. 9. The light irradiation device according to claim 8, wherein the light emitted from the light emitting element is light having a wavelength in the ultraviolet region.

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