WO2017078030A1

WO2017078030A1 - Backlight module

Info

Publication number: WO2017078030A1
Application number: PCT/JP2016/082496
Authority: WO
Inventors: 哲司横江; 上野　聡
Original assignee: 北陸電気工業株式会社
Priority date: 2015-11-02
Filing date: 2016-11-01
Publication date: 2017-05-11

Abstract

Provided is a backlight module that can be manufactured lighter more cheaply than previously, and for which it is possible to obtain as much heat dissipation performance as needed. Copper foil patterns (32A and 32B) that are formed on a substrate front surface (31A) and a substrate back surface (31B) of a circuit substrate (35) include a power supply copper foil pattern (37A) that supplies power to a plurality of light-emitting elements (38), said light-emitting elements (38) being formed from light-emitting diodes (LEDs), and a heat dissipation copper foil pattern (37B) that constitutes a portion of a heat-dissipating structure. An air flow recess (54) is formed between a pair of light source array storage recesses (53) in a light guide plate back surface section (52) of a light guide plate (5), said light guide plate back surface section (52) facing the substrate front surface of the circuit substrate (35), said air flow recess (54) opening toward the substrate front surface (31A), opening toward both sides in the directions in which a pair of light source arrays (39) extend, and constituting a portion of a heat-dissipating structure. A main reflection layer (55) that reflects light into the light guide plate (5) is formed on a surface of the light guide plate back surface section (52), said surface including at least the air flow recess (54).

Description

Backlight module

The present invention relates to a backlight module used for a backlight or the like of a liquid crystal device.

In Japanese Patent No. 4525492, a circuit board provided with a light source array composed of a plurality of LED elements (light emitting elements) is arranged opposite to a pair of side surfaces of a light guide plate, and a heat radiating portion is provided on the back side of the light guide plate. A backlight module in which a heat dissipating frame made of a metal material is arranged for the configuration is disclosed.

Japanese Patent No. 4525492

Conventionally, heat is dissipated from a plurality of light emitting elements using a heat dissipating frame made of a metal material. However, a heat dissipation frame made of a metal material has a problem that it is expensive and heavy.

An object of the present invention is to provide a backlight module that can be manufactured at a lower cost and lighter than the conventional one, and that can obtain necessary and sufficient heat dissipation performance.

The backlight module of the present invention includes a substrate unit in which a plurality of light emitting elements are arranged on a substrate surface of a circuit board having a wiring pattern so as to form a light source array along at least one side of the substrate surface; A heat dissipating structure that dissipates heat radiated from the unit, a light guide plate that is disposed on the circuit board and radiates light emitted from a plurality of light emitting elements from the light guide plate surface portion, and is disposed on the light guide plate surface portion side And a front panel that does not have optical transparency and covers at least a part of the outer peripheral surface that is continuous with the outer edge portion of the light guide plate surface portion and the light guide plate surface portion. In the present invention, the circuit board has a heat dissipation copper foil pattern that forms a part of the heat dissipation structure formed on the front and back surfaces of the insulating substrate, and supplies power to a plurality of light emitting elements on at least the substrate surface of the insulating substrate. A copper foil pattern for feeding is formed. In addition, on the rear surface of the light guide plate facing the substrate surface of the circuit board of the light guide plate, an opening toward the substrate surface, and a recess for storing the light source array surrounding the light source array with a space between the light source array, Air circulation recesses are formed that open toward both sides of the light source array and open toward both sides of the light source array. And the main reflection layer which reflects light in the light guide plate is formed in the surface surrounding the recessed part for air circulation at least on the back surface part of the light guide plate.

According to the present invention, the heat dissipation copper foil pattern is positively provided on the circuit board, and the air circulation recess is provided, so that the necessary and sufficient heat dissipation performance is provided without providing a metal heat dissipation frame as in the prior art. Can be obtained. And since there is no metal heat dissipation frame, the price of the backlight module can be reduced and the overall weight can be reduced.

It is preferable that a pair of light source rows each composed of a plurality of light source elements are arranged along a pair of sides facing in the surface direction of the substrate surface. In this way, the required illuminance can be obtained even when the size is increased.

A pair of light source array storage recesses for storing a pair of light source arrays, respectively, is formed on the rear surface of the light guide plate, and an air circulation recess is formed between the pair of light source array storage recesses. Is preferred. The air circulation recess can be formed as large as possible.

The air circulation recess is preferably curved so as to be convex toward the surface of the light guide plate and has a shape in which the cross-sectional shape in a direction perpendicular to the direction in which the light source array extends has an arcuate shape. Even if the concave portion for air circulation is provided in the light guide plate, the mechanical strength of the light guide plate can be suppressed from decreasing.

It is preferable that a first sub-reflection layer that reflects light is formed in the light guide plate at a portion of the back surface of the light guide plate that contacts the substrate surface. Efficiency can be increased.

It is preferable that a second sub-reflective layer that reflects light is formed in the light guide plate in contact with the light guide plate surface portion of the front panel. Efficiency can be increased.

The main reflection layer, the first sub-reflection layer, and the second sub-reflection layer are preferably formed of a metal thin film such as plating or sputtering or a light-reflective white resin. Even when cooling air flows through the air circulation recess, dust can be prevented from entering between the reflective layer and the light guide plate.

The front panel and the substrate unit are preferably connected to each other by a connecting structure with a light guide plate interposed therebetween. Easy to assemble.

The light emitting element is optional, but may be an LED with low power consumption.

Also, it is preferable to use a front panel and a light guide plate that are integrally molded by two-color molding. Dust does not enter between the front panel and the light guide plate, and the assembly of the module can be improved. In addition, the light diffusing substance is entirely dispersed in the light guide plate, and the light orientation is improved when the continuous uneven parts constituting the Fresnel lens are formed on the surface of the light guide plate of the light guide plate. it can.

It is a cross section of the backlight module of embodiment of this invention. It is a disassembled perspective view of the backlight module of this Embodiment. It is a bottom view of a substrate unit. (A) And (B) is a perspective view of the unit by which a light-guide plate and a front panel are combined.

Hereinafter, embodiments of a backlight module according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the backlight module 1 of the present embodiment, and FIG. 2 is an exploded perspective view of the backlight module 1 of the present embodiment. The backlight module 1 according to the present embodiment includes a substrate unit 3, a light guide plate 5, and a front panel 7. The board unit 3 includes, for example, a circuit board 35 constituted by a double-sided copper foil board 34 in which

copper foil patterns

32A and 32B are formed on a board front face 31A and a board back face 31B of an insulating board 31 such as a glass epoxy resin board. Yes. As the insulating substrate, other high thermal conductive glass composite materials other than glass epoxy resin, for example, a substrate material sold by Panasonic Corporation with ECOOL (registered trademark): thermal conductivity 1.5 W / m · K, etc. Of course, it may be used.

The

copper foil patterns

32A and 32B formed on the substrate front surface 31A and the substrate back surface 31B of the circuit board 35 include a power supply copper foil pattern 37A for supplying power to a plurality of light emitting elements 38 made of light emitting diodes LED, and a heat dissipation structure. The copper foil pattern 37B for thermal radiation which comprises a part is contained. In the present embodiment, four light emitting elements 38 are arranged on a plurality of electrodes (not shown) included in a feeding copper foil pattern 37 A formed along a pair of sides of the substrate surface 31 A of the rectangular circuit board 35. Are arranged to constitute. The feeding copper foil pattern 37A is connected to a pair of power supply electrodes (not shown). The four light emitting elements 38 are electrically connected in series. Then, four mounting holes 40 are formed at the four corners of the circuit board 35, and a pair of mounting holes 41 are also formed at the center of the other pair of sides where the pair of light source rows 39 is not disposed. Has been.

The light guide plate 5 and the front panel 7 are integrally formed by a double mold (two-color molding / different material molding), that is, a molding technique in which different materials (materials) are combined and molded integrally. What is necessary is just to shape | mold the part of the front panel 7 used as the secondary side integrally with the light guide plate 5 of the primary side after shape | molding the part of the light guide plate 5 used as the primary side. In the present embodiment, the light guide plate 5 and the front panel 7 are separately formed in order to form a second sub-reflection layer described later. The light guide plate 5 is formed of a light-transmitting acrylic material, and is disposed on the circuit board 35 to radiate light emitted from the eight light emitting elements 38 from the light guide plate surface portion 51. As a material of the light guide plate 5, polycarbonate (PC) resin, cycloolefin resin (COP), or the like can be used. In the present embodiment, the light diffusing substance is entirely dispersed in the light guide plate 5. As the light diffusing substance, mica, titanium dioxide-coated mica, or the like can be used. Of course, it is not necessary to add the light diffusing substance into the light guide plate 5.

The front panel 7 is disposed on the light guide plate surface portion 51 side, covers the outer edge portion of the light guide plate surface portion 51 and a part of the outer peripheral surface continuous with the light guide plate surface portion 51, and leaks light from the light guide plate 5. In order to prevent this, it is made of a resin material such as an acrylic material that does not have optical transparency.

Specifically, the light guide plate back surface portion 52 facing the substrate surface of the circuit board 35 of the light guide plate 5 is opened toward the substrate surface 31A, and a pair of light source rows 39 is spaced apart from each other. A light source column storage recess 53 is formed to surround each of the light source columns 39. The light guide plate rear surface 52 of the light guide plate 5 facing the substrate surface of the circuit board 35 is opened between the pair of light source array storage recesses 53 toward the substrate surface 31A and the pair of light source arrays 39 extends. Air circulation recesses 54 are formed that open toward both sides in the direction and constitute a part of the heat dissipation structure. The air circulation concave portion 54 is curved so as to be convex toward the light guide plate surface portion 51 side, and has a shape in which a cross-sectional shape in a direction orthogonal to the direction in which the pair of light source rows 39 extends has an arcuate shape. With such a shape, it is possible to suppress the mechanical strength of the light guide plate 5 from being lowered even if the air circulation recess 54 is provided in the light guide plate 5. A main reflection layer 55 that reflects light into the light guide plate 5 is formed on the surface surrounding the air circulation recess 54 of the light guide plate back surface portion 52. In addition, a first sub-reflection layer 56 that reflects light is formed in the light guide plate 5 at a portion of the light guide plate rear surface portion 52 that contacts the substrate surface 31 A. Further, the light guide plate surface portion 51 of the light guide plate 5 is formed with a concavo-convex portion 59 continuous in the longitudinal direction of the light guide plate 5 so as to constitute a Fresnel lens. The concavo-convex portion 59 has a shape in which the cross-sectional shape is a saw-tooth shape.

The pair of light source array storage recesses 53 is formed in an arc shape whose cross section has an arc shape that is open toward the substrate surface 31A and extends in the direction in which the light source array 39 extends in a portion corresponding to the light emitting portion of the light emitting element 38. A recess 53A is provided. A pair of edge portions of the light guide plate surface portion 51 located at both ends in the longitudinal direction of the light guide plate 5 includes a pair of arc-shaped convex portions 57 that extend in the direction in which the light source array 39 extends and have a circular cross section. A deformation corner 58 is formed.

The front panel 7 includes a frame portion 72 configured to form a rectangular opening 71 that exposes most of the light guide plate surface portion 51 of the light guide plate 5 at the center. The pair of frames 72A and 72b out of the four frames 72A to 72D constituting the frame portion 72 are respectively formed with recesses 73 having shapes similar to the pair of deformation corner portions 58 of the light guide plate 5, respectively. . A second sub-reflection layer 74 that reflects light into the light guide plate 5 is formed on the inner surface of the recess 73. The light incident from the light emitting element 38 into the light guide plate 5 is formed by the arc shape, the shape of the convex portion 57, the shape of the concave portion 73, and the main reflection layer 55, the first sub reflection layer 56 and the second sub reflection layer 74. reflect. The light reflected in the light guide plate 5 is radiated linearly through a Fresnel lens formed on the light guide plate surface portion 51 of the light guide plate 5. In the frames 72 C and 72 D of the front panel 7, fitting protrusions 75 are integrally provided so as to be fitted in the mounting holes 41 provided in the circuit board 35. The fitting projection 75 is locked to the edge of the mounting hole 41 and has a shape that can be prevented from easily coming out of the mounting hole 41. Although not shown, as shown in FIG. 4, bottomed mounting hole portions 78 into which the pin member 8 shown in FIG. 2 is fitted are respectively provided at the four corners of the frame portion 72 of the front panel 7. Is formed. The pin member 8 passes through the mounting holes 40 provided at the four corners of the circuit board 35 and is fitted into the mounting holes 78 provided at the four corners of the frame portion 72 of the front panel 7. The light guide plate 5 and the substrate unit 3 are integrated. In the present embodiment, the pin member 8, the fitting protrusion 75, the attachment holes 40 and 41, and the attachment hole portion 78 constitute a connection structure.

The main reflective layer 55, the first sub-reflective layer 56, and the second sub-reflective layer 74 are made of a diffusely-reflecting chromium or zinc plating, a metal thin film such as sputtering, or a light-reflective white resin. Can do.

Incidentally, the dimensions of each part of the present embodiment are as follows. The vertical and horizontal dimensions of the front panel 7 are 3 inches × 7 inches (76.2 mm × 101.6 mm), the thickness dimension of the backlight module 1 is 10 mm, and the maximum thickness dimension of the passage 9 is 5 mm.

According to the present embodiment, the heat dissipation structure is formed by the

copper foil patterns

32A and 32B provided on both surfaces of the circuit board 35, and is formed between the air circulation recess 54 of the light guide plate 5 and the substrate surface 31A of the substrate unit 3. The substrate unit 3 can be cooled by heat radiation caused by cooling air flowing through the passage 9 (heat radiation structure). As a result, according to the present embodiment, necessary and sufficient heat dissipation performance can be obtained without providing a metal heat dissipation frame as in the prior art.

DESCRIPTION OF SYMBOLS 1 Backlight module 3 Substrate unit 5 Light guide plate 7 Front panel 8 Pin member 9 Passage 31 Insulating substrate 31A Substrate surface 31B Substrate back

surface

32A, 32B Copper foil pattern 34 Double-sided copper foil substrate 35 Circuit board 37A Feeding copper foil pattern 37B For heat dissipation Copper foil pattern 38 Light emitting element 39 Light source array 40 Mounting hole 41 Mounting hole 51 Light guide plate surface 52 Light guide plate back surface 53 Light source array storage recess 54 Air circulation recess 53A Arc-shaped recess 55 Main reflection layer 56 Sub-reflection layer 57 Circle Arc-shaped convex portion 58 Deformation corner portion 59 Concavity and convexity portion 71 Opening portion 72 Frame portion 73 Concavity portion 74 Sub-reflection layer 75 Fitting projection 78 Mounting hole portion

Claims

A substrate unit in which a plurality of light emitting elements are arranged so as to form a light source array along at least one side of a substrate surface of a circuit board having a wiring pattern;
A heat dissipation structure that dissipates heat radiated from the substrate unit;
A light guide plate that is disposed on the circuit board and emits light emitted from the plurality of light emitting elements from a surface portion of the light guide plate;
A light-transmitting front panel that is disposed on the light guide plate surface portion side and covers at least part of the outer peripheral surface of the light guide plate surface portion and the outer peripheral surface continuous with the light guide plate surface portion;
The circuit board has heat dissipation copper foil patterns forming a part of the heat dissipation structure formed on a front surface and a back surface of an insulating substrate, and supplies power to the plurality of light emitting elements on at least the substrate surface of the insulating substrate. A copper foil pattern for feeding is formed,
A light source row housing that opens toward the substrate surface and surrounds the periphery of the light source row with a space between the light source row and a back surface portion of the light guide plate facing the substrate surface of the circuit board. A concave portion for air flow and a concave portion for air circulation that is open toward both sides in the direction in which the light source array extends and that opens toward the substrate surface and constitutes a part of the heat dissipation structure is formed.
A backlight module, wherein a main reflection layer for reflecting light is formed in the light guide plate on at least a surface of the back surface of the light guide plate surrounding the air circulation recess.
2. The backlight module according to claim 1, wherein a pair of the light source rows each composed of the plurality of light source elements is disposed along a pair of sides facing the surface direction of the substrate surface.
A pair of light source array storage recesses for storing the pair of light source arrays, respectively, are formed on the back surface of the light guide plate.
The backlight module according to claim 2, wherein the air circulation recess is formed between the pair of light source array storage recesses.
2. The air circulation recess has a shape that is curved so as to be convex toward the surface of the light guide plate and has an arcuate cross-sectional shape in a direction perpendicular to the direction in which the light source array extends. The backlight module of any one of thru | or 3.
5. The backlight according to claim 1, wherein a first sub-reflection layer that reflects light is formed in the light guide plate at a portion of the back surface of the light guide plate that contacts the substrate surface. 6. module.
The backlight module according to any one of claims 1 to 5, wherein a second sub-reflection layer that reflects light is formed in the light guide plate in contact with the light guide plate surface portion of the front panel.
The main reflection layer, the first sub-reflection layer, and the second sub-reflection layer are formed of a metal thin film such as plating or sputtering or a light-reflective white resin. The backlight module according to claim 1.
The backlight module according to claim 1, wherein the front panel and the substrate unit are connected to each other by a connecting structure with the light guide plate interposed therebetween.
The backlight module according to any one of claims 1 to 8, wherein the light emitting element is an LED.
The front panel and the light guide plate are integrally molded by two-color molding,
In the light guide plate, the light diffusing material is dispersed as a whole,
The backlight module according to claim 1, wherein a continuous uneven portion constituting a Fresnel lens is formed on a surface portion of the light guide plate of the light guide plate.