KR101239722B1 - Liquid crystal display device - Google Patents

Abstract

In the liquid crystal display device which accommodates the liquid crystal display panel (1) and the LED backlight (BL) and also serves as a heat sink substrate (5), the LED backlight (BL) is a light guide plate (3), An LED light source array mounted on the mounting substrate 21 is included. Thermally conductive members 20, 31, 32, and 34 are interposed between the mounting substrate 21 and the heat sink substrate 5. The heat storage of the mounting substrate on which the LED light source is mounted is reduced, and the temperature rise of the LED light source is reduced (FIG. 1).
[Patent Document] Japanese Unexamined Patent Publication No. 2002-75038
[Patent Document] Japanese Unexamined Patent Publication No. 2003-281924

Description

[0001] LIQUID CRYSTAL DISPLAY DEVICE [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a liquid crystal display panel and a backlight, and more particularly, to a liquid crystal display device using a light emitting diode (hereinafter simply referred to as LED) as a light source.

Conventionally, in the display system of a liquid crystal display device, a transmissive or semi-transmissive liquid crystal display device is comprised by arrange | positioning the liquid crystal display panel and the backlight which supplies the light transmitted to a liquid crystal display panel.

Generally, a backlight consists of a light source and a light guide plate, and uses a small fluorescent tube called a CCFL (cold cathode tube) as a light source. In addition, one main surface of the light guide plate is opposed to correspond to the display area of the liquid crystal display panel, and a diffusing portion for diffusing and reflecting light on the surface side is formed on the main surface (referred to as the outer surface) opposite to the one main surface. It is.

The CCFL light source is disposed at the end face of the light guide plate, and the light of the CCFL incident from the end face of the light guide plate is transmitted into the light guide plate, diffused and reflected from the outer surface side of the light guide plate, and is emitted from the surface of the light guide plate toward the liquid crystal display panel. As a result, the light source is converted into a uniform planar light source and used as a light source of the liquid crystal display device.

However, the CCFL light source encloses Hg (mercury) in the discharge tube, and ultraviolet rays emitted from the mercury excited by the discharge touch the phosphor on the CCFL tube wall and are converted into visible light.

For this reason, in consideration of the environmental aspect, use of an alternative light source is called for by suppressing the use of harmful mercury.

In order to turn on the CCFL, a high voltage high frequency lighting circuit is required, and since high frequency noise is generated, noise countermeasure is required separately, and there is a problem that it is difficult to light at low temperatures.

Meanwhile, as a new light source, a backlight using a light emitting diode module (LED light source) in which a light emitting diode chip having a characteristic of point light source is accommodated has been developed.

BACKGROUND ART A backlight using this LED light source is becoming popular as a backlight of a liquid crystal display panel in accordance with lower cost, improved luminous efficiency, and environmental regulations.

At the same time, with the increase in the luminance and size of the display area of liquid crystal display devices, the demand for mounting a plurality of LED light sources is increasing.

Therefore, in order to make an LED backlight used for a high-brightness large-size liquid crystal display panel, it is necessary to convert the LED light source which is a point light source into the surface light source which emits uniformly (the light source converted into uniform light on the exit surface of the light guide plate). . For this purpose, it is necessary to control the material and structure of the diffusion part of the outer surface of the light guide plate, and arrange | position an LED light source in the optimal position according to the directivity of an LED light source.

One problem here is that the LED light source and its surrounding temperature rise due to the heat generation of the LED light source, and the luminous efficiency and lifetime of the LED light source decrease.

Although the LED light source improves luminous efficiency by recent improvement, luminous efficiency is about 10% in the present state, and the remaining 90% is emitted as heat.

In a backlight using an LED as a light source, this heat is accumulated on the LED and the substrate on which the LED is mounted, and as the LED or its ambient temperature rises, the LED itself lowers its luminous efficiency.

Regarding the lifetime, the estimated lifetime data (luminance half-life) at the forward current IF = 20 mA of the top view LED is shown in FIG. It is found from FIG. 25 that the lifetime is about 12000 hours at 25 ° C and only about 5500 hours at 50 ° C, and the life is shortened as the ambient temperature of the LED rises.

In addition, the heat generated from the LED may be a cause of damaging the wiring of the LED or the mounting board on which the LED is mounted.

In addition, in order to increase the brightness of the backlight, if the number of LED mountings is increased, the amount of heat generated increases, and this heat generation cannot be ignored.

In the liquid crystal display device provided with an LED backlight, the present invention reduces the heat storage of the mounting substrate on which the LED light source is mounted and reduces the temperature rise of the LED light source, thereby suppressing the decrease in luminous efficiency of the LED light source and emitting light. It is an object of the present invention to provide a liquid crystal display device capable of preventing damage to a diode chip and enabling bright long-life liquid crystal display.

The liquid crystal display device of the present invention comprises a liquid crystal display panel comprising a display area composed of a plurality of pixel regions with a liquid crystal interposed between a pair of substrates having a display electrode and an alignment film, and one substrate of the liquid crystal display panel. A liquid crystal display including a light guide plate disposed at an outer side of the display area, a backlight including an LED light source array disposed at an end surface of the light guide plate, the liquid crystal display panel and the backlight, and a heat sink substrate; In the apparatus, the LED light source array includes a mounting substrate and an LED container mounted in a plurality of arrays on the LED mounting surface of the mounting substrate and in which a light emitting diode chip is accommodated, and between the mounting substrate and the heat sink substrate. The heat conductive member is interposed therebetween.

In this liquid crystal display device, a heat conductive member is interposed between the mounting substrate on which the LED light source constituting the LED light source array is mounted and the heat sink substrate, thereby efficiently conducting heat from the mounting substrate to the heat sink substrate, It can diffuse and radiate efficiently.

Therefore, by reducing the heat storage of the mounting substrate on which the LED light source is mounted and reducing the temperature rise of the LED light source, the decrease in luminous efficiency of the LED light source can be suppressed. As a result, it is possible to provide a liquid crystal display device capable of preventing damage to the LED light source and enabling bright long-life liquid crystal display.

It is preferable that the said heat conductive member consists of a heat conductive sheet with high elasticity.

When the thermally conductive member is press-contacted, the elasticity of the thermally conductive sheet corresponds to the minute unevenness of the contact surface between the mounting substrate and the heat sink substrate, and the thermal conductive sheet can be fused well to remove the air layer on the contact surface, thereby preventing from the LED light source. It is possible to efficiently conduct heat to the heat sink substrate.

It is preferable that the said heat conductive sheet is adhere | attached on the heat sink board | substrate with the adhesive agent with high fluidity | liquidity.

By interposing an adhesive having high fluidity between the mounting substrate and the heat sink substrate, heat conduction between the mounting substrate and the heat sink substrate can be efficiently performed. This is because bubbles are present in the resin as in the conventional conductive resins and do not interfere with thermal conduction. In addition, even in the supply operation of the adhesive, the adhesive can be supplied simply and reliably using the capillary phenomenon, and the LED container can be firmly fixed to the mounting substrate.

The thermally conductive member may be in close contact with the heat sink substrate through a fluid having low fluidity.

By using a fluid having low fluidity, the fluidity is low due to minute unevenness at the contact surface between the rear surface of the mounting substrate (the surface opposite to the LED mounting surface) and the thermally conductive member, and the contact surface between the thermally conductive member and the heat sink substrate. The fluid enters and the compatibility of the mounting substrate, the thermal conductive member, the thermal conductive member, and the heat sink substrate is improved. Therefore, the air layer can be eliminated, and the heat radiation efficiency from the mounting substrate to the heat sink substrate can be improved.

The mounting substrate of the LED light source array is disposed substantially in a direction perpendicular to the main surface of the light guide plate, and the LED container constituting the LED light source includes a light emitting surface for emitting light emitted from the light emitting diode chip, and a light emitting surface thereof The case body-shaped LED container which has the back surface and four side surface which opposes, and the back surface of the said LED container is made into LED mounting surface can be employ | adopted the structure mounted on the said mounting board | substrate.

The structure in which the mounting substrate is disposed substantially perpendicular to the light guide plate is specifically shown in FIGS. 1, 11, 12, 15, and 18.

In this configuration, since the LED container is mounted on the mounting substrate with the rear surface of the LED container as the LED mounting surface, the mounting substrate is arranged at an angle substantially perpendicular to the light incidence direction of the light guide plate. .

The heat sink substrate may have two or more surfaces curved in an L shape, and each surface may be disposed to face the rear surface of the mounting substrate and the outer surface of the light guide plate.

By this arrangement, the heat sink substrate is formed on the heat sink substrate arranged in an L-shaped cross-section so as to correspond to the outer surface of the light guide plate, and the heat accumulated on the mounting substrate from the rear surface side of the mounting substrate is effectively provided via the heat conductive member. Can be delivered to.

The thermally conductive member includes a first thermally conductive member covering the rear surface of the LED mounting surface of the mounting substrate, and at least the light emitting surface of the LED container to expose the LED mounting surface and the LED container of the mounting substrate. It may also include a second thermally conductive member.

As a result, the heat transferred from the LED container to the mounting substrate among the heat generated by the LED light source is transferred to the first and second heat conductive members, so that heat can be radiated to the heat sink substrate efficiently. Moreover, since the opening which exposes the LED container mounted on the mounting board | substrate is formed in the 2nd thermal conductive member, it does not disturb the light guide from an LED container to a light guide plate. This "first thermally conductive member" corresponds to the thermally conductive elastic member 31 illustrated later, and the "second thermally conductive member" corresponds to the thermally conductive elastic members 20, 32, 34 illustrated later. .

When the second thermally conductive member is disposed in close contact with the end surface of the light guide plate and the LED mounting surface of the mounting substrate, heat generated from the LED light source and accumulated on the LED mounting surface side of the mounting substrate is efficiently transmitted through the light guide plate side. To get out. The structure in which the "second heat conductive member is disposed in close contact with the end surface of the light guide plate and the LED mounting surface of the mounting substrate" will be described later with reference to FIGS. 12 and 18.

The heat conductive member and the second heat conductive member may be integrated. This integrated thermally conductive member is later illustrated as a thermally conductive elastic member 32 in FIGS. 15 to 18.

In addition, the liquid crystal display device of the present invention, the mounting substrate of the LED light source array is arranged in a direction substantially parallel to the light guide plate, the LED container is a light emitting surface for emitting light emitted from the light emitting diode chip And a case body-shaped LED container having a back surface and four side surfaces facing the light emitting surface, and one of the four side surfaces of the LED container may be mounted on the mounting substrate as an LED mounting surface.

In this liquid crystal display device, an LED container is mounted on a mounting substrate with one side-side LED container, that is, one of the side surfaces orthogonal to the LED mounting surface of the mounting substrate as the light emitting surface. The back surface of the mounting substrate is in close contact with the heat sink substrate and the case body.

In this liquid crystal display device, the heat sink substrate is substantially planar, and is disposed to face the rear surface of the mounting substrate and the outer surface of the light guide plate. This structure is shown later in FIG.

The thermally conductive member may expose at least the light emitting surface of the LED container to cover the LED mounting surface of the mounting substrate and the side surface of the LED container. In this case, the thermally conductive member interposed between the mounting substrate and the heat sink substrate is exemplified as the thermally conductive elastic member 34.

In addition, the liquid crystal display device of the present invention comprises a liquid crystal display panel comprising a display area composed of a plurality of pixel regions with a liquid crystal interposed between a pair of substrates having a display electrode and an alignment film, and one of the liquid crystal display panels. A backlight including a light guide plate disposed to correspond to the display area, an LED light source array disposed on an end surface of the light guide plate, the liquid crystal display panel and the backlight; In the liquid crystal display device provided, the LED light source array includes a mounting substrate, and an LED container mounted in a plurality of arrays on the LED mounting surface of the mounting substrate and in which a light emitting diode chip is accommodated, wherein the mounting substrate includes the LED. The mounting surface and its rear surface are covered by the thermally conductive member by exposing at least the light emitting surface of the LED container, and the thermally conductive member has an upper surface. Is in contact with or adhered to the heat sink substrate.

In this liquid crystal display device, the LED mounting surface and the rear surface of the mounting substrate are covered with an integrated thermal conductive member. Therefore, heat generated from the LED container can be radiated from both surfaces of the mounting substrate through the heat sink substrate through the heat conductive member.

The heat conductive member has a cross-sectional shape (U) and has a notch for exposing the light emitting surface of the LED container.

In this configuration, a long-shaped mounting substrate on which an LED light source array is mounted has a cross section that covers three surfaces of four surfaces (one pair of main surfaces and one pair of end surfaces in the longitudinal direction) of the mounting substrate. U) It is covered with a thermally conductive member in the shape of a shape. This LED mounting surface and the thermally conductive member having a cross-section (U) shape covering the rear surface thereof correspond to the thermally conductive elastic member 32 shown in FIGS. 15 and 18. Since the notch part which exposes the light emitting surface of an LED container is formed in one surface of the cross-section (U) -shaped heat conductive member, it does not prevent supplying light emitted from an LED container to a light guide plate reliably.

It is preferable that the said heat conductive member consists of a material which has elasticity.

The elasticity of the thermally conductive member corresponds to the minute unevenness of the contact surface between the mounting substrate and the heat sink substrate, and the thermal conductive sheet can be fused well by pressing the thermally conductive member to remove the air layer on the contact surface. In addition, by covering the mounting substrates from the three surfaces, it is excellent in shock absorption.

It is preferable that the said heat conductive member is adhere | attached to the heat sink board | substrate with the adhesive agent with high fluidity | liquidity. By interposing an adhesive having high fluidity between the mounting substrate and the heat sink substrate, heat conduction between the mounting substrate and the heat sink substrate can be efficiently performed.

The thermally conductive member may be in close contact with the heat sink substrate through a fluid having low fluidity. By using a fluid having low fluidity, the fluid having low fluidity enters the minute unevenness at the contact surface between the rear surface of the mounting substrate and the thermal conductive member and the contact surface between the thermal conductive member and the heat sink substrate, and thus the mounting substrate and the thermal conductive member, and the thermal conductivity The compatibility of the member with the heat sink substrate is improved. Therefore, the air layer can be eliminated, and the heat radiation efficiency from the mounting substrate to the heat sink substrate can be improved.

The operation of the liquid crystal display device of the present invention described above increases the display area of the liquid crystal display panel 1, enlarges the shape of the light guide plate 3, and supplies sufficient light to the enlarged light guide plate 3. To this end, the more the plurality of LED light sources 2 are mounted on the mounting substrate 21, the greater the effect.

According to the liquid crystal display device of the present invention, in the liquid crystal display device having an LED backlight, the heat storage of the mounting substrate on which the LED light source is mounted is reduced, and the temperature rise of the LED light source is reduced, thereby reducing the luminous efficiency of the LED light source. In addition, it has the effect of preventing damage to the light emitting diode chip and enabling bright long-life liquid crystal display.

1 is a cross-sectional view of a liquid crystal display device according to an embodiment of the present invention.
2 is a schematic perspective view of a liquid crystal display of the present invention.
3 is a cross-sectional view showing the structure of a liquid crystal display panel used in the liquid crystal display device of the present invention.
4 is a schematic perspective view of the mounting substrate of the LED light source viewed from the LED mounting surface side.
5 is a schematic perspective view of the mounting substrate of the LED light source viewed from the back side.
6 is a schematic cross-sectional view of the mounting substrate of the LED light source according to the present invention.
FIG. 7 is an enlarged cross-sectional view of part A of FIG. 6.
8 is a schematic perspective view of an LED light source array in which a plurality of LED light sources are mounted on a mounting substrate.
9 is a schematic view showing the structure of the LED light source.
10 is a perspective view of an L-shaped heat conductive member.
11 is a schematic cross-sectional view of a liquid crystal display device according to another embodiment of the present invention.
12 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
13 is a perspective view of a second heat conductive member.
14 is a schematic exploded perspective view of an LED light source array using a second thermally conductive member.
15 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
16 (a) to 16 (c) are perspective views of a cross-sectional U (U) -shaped heat conductive member used for the liquid crystal display of FIG. 15, respectively.
17 (a) to 17 (c) are perspective views of a metal case used for a thermally conductive member having a cross-section (U) shape, respectively.
18 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
19 is a schematic cross-sectional view of a liquid crystal display device according to still another embodiment of the present invention.
20 is a schematic perspective view of an LED light source array used in the liquid crystal display of FIG. 19.
FIG. 21 is a perspective view of a thermally conductive member used in the liquid crystal display of FIG. 19.
22 is a schematic cross-sectional view showing an embodiment of a mounting substrate.
23 is a schematic cross-sectional view showing another embodiment of the mounting substrate.
24 is a schematic perspective view of an LED light source array.
25 is a characteristic diagram showing the relationship between the ambient temperature and the life of an LED chip.

The above-mentioned or another advantage, characteristic, and effect in this invention become clear by description of embodiment described below with reference to an accompanying drawing.

<Overall Structure>

1 is a schematic cross-sectional view of a liquid crystal display device of the present invention, and FIG. 2 is a perspective view of the liquid crystal display device.

3 is a cross-sectional view of a liquid crystal display panel used in the liquid crystal display device of the present invention.

The liquid crystal display device of the present invention includes a liquid crystal display panel (1), a backlight (BL) including a light guide plate (3) and an LED light source (2), an upper case body (4) that accommodates both, and a lower case body ( It is mainly composed of 5).

The upper case 4 protects the liquid crystal display panel 1, and the lower case 5 serves as a heat sink substrate that protects the backlight BL and emits heat to the outside. Paying attention to this heat dissipation function, the lower case body 5 is called "heat sink board | substrate 5".

<LCD panel>

As shown in Fig. 3, the liquid crystal display panel 1 includes a transparent substrate 12 on one side which is one substrate, a transparent substrate 11 and a transparent substrate 11 and 12 on the lower side which are the other substrate. It has the liquid crystal layer 13 sandwiched between. The liquid crystal layer 13 is surrounded by the sealing part 14.

In addition, a display electrode 15, an alignment film, and the like are formed on the inner surface of the lower transparent substrate 11, and a display electrode 16, an alignment film, and the like are formed on the inner surface of the upper transparent substrate 12. .

The display pixels 15 arranged in a matrix are formed by the display electrodes 15 of the lower transparent substrate 11 and the display electrodes 16 of the upper transparent substrate 12.

Although not shown in the drawings, the lower transparent substrate 11 and the upper transparent substrate 12 are provided with a polarizing plate, a retardation film, and a diffusion film as necessary.

In the case where the liquid crystal display device is a transmissive liquid crystal display device, the display electrodes are all composed of transparent electrodes, and the display pixel region transmits light from the backlight BL to the display surface side.

In the case of a semi-transmissive liquid crystal display device, the display pixel region includes a light reflecting portion, part of which is made of a reflective metal film, and a light transmitting portion, of which part can transmit light of the backlight BL.

In this semi-transmissive liquid crystal display device, external light incident from the display surface side is reflected by the light reflecting portion of the pixel region, returned to the display surface side, and the light of the backlight BL is transmitted through the light transmitting portion.

Thereby, when external light is strong, it displays in a reflective mode, and when external light is weak, it can display in a transmissive mode.

Further, in order to achieve color display, a color filter may be formed in any one of the lower transparent substrate 11 or the upper transparent substrate 12 in the pixel region.

Further, in the liquid crystal display device of the present invention, a switching element may be formed in each pixel region of the lower transparent substrate 11 or the upper transparent substrate 12 to control the display for each pixel region.

In addition, a wiring pattern for connecting the display electrode 15 or the switching element to an outer periphery of the display area of either the upper transparent substrate 12 or the lower transparent substrate 11, for example, the upper transparent substrate 12. In this wiring pattern, a drive circuit 19 for supplying a predetermined signal and a predetermined voltage may be provided, or an input terminal for connecting to an external drive circuit may be provided.

In addition, the display electrode of the board | substrate on the side which does not form a wiring pattern, for example, the lower transparent substrate 11, may be connected to the said wiring pattern through the conductive filter arrange | positioned on the outer periphery between both board | substrates 11 and 12. FIG. .

The material of the lower transparent substrate 11 and the upper transparent substrate 12 may exemplify glass, a transparent plastic, or the like. The display electrodes 15 and 16 are made of ITO, tin oxide, or the like which is a transparent conductive material. In addition, the reflective metal film which comprises a light reflection part is comprised from aluminum, titanium, etc. In addition, the alignment film is made of a polyimide resin that is subjected to a rubbing treatment. When a color filter is provided, dyes, pigments, and the like must be added to the resin to form filters of red, green, and blue colors for each pixel region. In addition, black resin may be used between the filters and around the pixel region for the purpose of shielding light.

The lower transparent substrate 11 and the upper transparent substrate 12 are bonded to each other through the sealing portion 14 and pressed, and are made of a nematic liquid crystal or the like rather than an opening of a part of the sealing portion 14. The liquid crystal material is injected, and then the injection port is sealed.

In this bonding, both display electrodes 15 and 16 arranged on both transparent substrates 11 and 12 are orthogonal to each other. The intersection of the display electrodes becomes each pixel area, and the pixel areas are collectively formed into a display area.

In this way, the liquid crystal display panel 1 is configured.

<Backlight>

The backlight BL is disposed outside the lower transparent substrate 11 of the liquid crystal display panel 1 (lower side in the drawing).

As shown in FIG. 1, the backlight BL is disposed in parallel with the LED light source 2, the light guide plate 3, the lens sheet 3a, the diffusion sheet 3b, the reflective sheet 3c, and the light guide plate 3. A mounting board 21 having a long length and a heat conductive sheet 31 which is a heat conductive member are provided.

This heat conductive sheet 31 is preferably formed of a member having elasticity such as rubber. Therefore, it is called "thermally conductive elastic sheet 31" below.

The light guide plate 3 has a shape corresponding to the display area of the liquid crystal display panel 1. One main surface (surface from which light is emitted) of the light guide plate 3 is disposed to face the lower transparent substrate 11.

The light guide plate 3 is made of a transparent resin plate. You may contain a light-scattering member in the resin component. The lens sheet 3a and the diffusion sheet 3b are arranged on one main surface of the light guide plate 3, and the light propagating in the light guide plate 3 on the other main surface (called an outer surface) of the light guide plate 3. Reflecting sheet 3c for radiating the light to one main surface side is disposed.

Instead of the reflective sheet 3c, grooves for directly diffusing and reflecting light may be formed on the outer surface of the light guide plate 3, or a coating film having a diffusion / reflection function may be formed.

In addition, you may form this reflecting sheet 3c in three end surfaces except the end surface where the LED light source 2 is arrange | positioned among the four end surfaces of the light guide plate 3.

The LED light source 2 is mounted on the mounting substrate 21, as shown in FIGS.

The LED light source 2 is the LED chip 23a which has a light emitting part, an anode electrode, and a cathode which consists of semiconductor materials, and the LED container 23b which consists of heat-resistant resin materials, a ceramic material, etc. like the sectional drawing shown in FIG. Consists of

The LED container 23b of this LED light source 2 has a light emitting surface, a back surface facing the light emitting surface, and four side surfaces, and the light emitting surface of the LED container 23b is as shown in FIG. 1. It is arrange | positioned so that the end surface part of the light guide plate 3 may be opposed.

A mortar shaped cavity 23d is formed on the light emitting surface of the LED container 23b, and an LED chip 23a is disposed and housed on the bottom of the cavity 23d.

The anode electrode and the cathode electrode of this LED chip 23a are connected to the terminal part 23c formed in the outer surface other than the light emitting surface of the LED container 23b.

In addition, a reflective paint may be applied to the inner wall surface of the mortar. The translucent resin may be filled in the cavity to embed the LED chip 23a.

As illustrated in FIG. 8, a plurality of LED light sources 2 having such a structure are mounted at predetermined intervals at a predetermined interval. The plurality of LED light sources 2 and mounting substrates 21 thus mounted are referred to as "LED light source arrays".

The mounting substrate 21 is made of a glass abandoned material epoxy resin substrate or a ceramic substrate.

On the LED mounting surface of the mounting substrate 21, a mounting metal film 22 for mounting the LED light source 2, a metal driving wiring 24 for supplying a predetermined driving current to the LED chip 23a, and a metal driving wiring ( A metal film pattern 25 spaced apart from 24 is formed.

In addition, the heat dissipation metal film 26 is formed on the surface facing the LED mounting surface, that is, the back surface of the substrate, substantially over the entire surface as shown in FIG. 5.

Further, a plurality of metal via hole conductors 27 are formed in the thickness direction of the mounting substrate 21 to connect the mounting metal film 22 and the heat dissipation metal film 26.

In addition, the terminal portion 23c of the LED light source 2 is connected to the metal drive wiring 24 via a conductive bonding member such as solder.

Each of the mounting metal film 22, the metal driving wiring 24, the metal film pattern 25, the heat dissipating metal film 26, and the metal via hole conductor 27 are made of copper or a copper-based metal material (copper material or copper plating). And a part of the metal drive wiring 24, the mounting metal film 22, the heat dissipation metal film 26, and the metal via hole conductor 27 are formed in the circled region A of FIG. As shown in FIG. 7 which is an enlarged view, it is covered by the solder layer 28. As shown in FIG.

In addition, the surface of the metal film pattern 25 is covered by the resin resist film 29. If the resist film 29 is white, the light leaked from the LED light source 2 can be efficiently supplied to the light guide plate 3.

<Thermally conductive member>

Next, a structure for dissipating heat generated from the LED light source 2 will be described.

When the backlight BL of the liquid crystal display device is driven (the LED light source 2 is turned on), heat is generated along with the light emission.

Heat generated in the LED chip 23a in the LED light source 2 is transmitted to the member having a larger area through the LED container 23b and the mounting substrate 21, and heat is radiated from the member to the outside air. There is.

As a countermeasure against this heat radiation, in the present embodiment, the light guide plate 3 is bent in an L-shape so as to face the outer surface of the light guide plate 3 and the surface (called a back surface) on which the metal film 26 for heat radiation of the mounting substrate 21 is formed. The heat sink board | substrate 5 which is a metal member is provided.

In the flat plate area | region of the heat sink board | substrate 5, ie, the area | region which faces the outer surface of the light guide plate 3, you may form a thermally conductive hole in order to increase contact with external air as needed.

In addition, the L-shaped region of the heat sink substrate 5 is in close contact with the heat dissipating metal film 26 of the mounting substrate 21 through the thermally conductive elastic sheet 31 as shown in FIG. 1. It is made.

10, the perspective view of this L-shaped thermally conductive elastic sheet 31 is shown.

The thermally conductive elastic sheet 31 is formed in an L-shaped cross section so as to contact the rear surface of the mounting substrate 21 and the lower surface of the mounting substrate 21 which is perpendicular to the surface.

The outer surface of this cross-sectional L-shaped heat conductive elastic sheet 31 and the heat sink substrate 5 made of cross-sectional L-shaped metal are in surface contact.

The thermally conductive elastic sheet 31 is made of a material such as elastic rubber having a good thin plate-like thermal conductivity, and its shape is flat.

Since the thermally conductive elastic sheet 31 has elasticity, minute irregularities on the surfaces of the mounting substrate 21 and the heat sink substrate 5 are absorbed, and the mounting substrate 21 and the thermal conductive elastic sheet 31 are separated from each other. The heat sink substrate 5 is surely brought into surface contact with almost no air layer interposed therebetween. By this structure, heat generated from the LED light source 2 is transmitted from the LED container 23b to the mounting substrate 21, and stably radiates heat to the heat sink substrate 5 through the thermally conductive elastic sheet 31. do. Thereby, the heat which generate | occur | produced in the LED chip 23a can escape to the heat sink board | substrate 5, As a result, the LED light source 2 and the temperature of the surrounding can be reduced.

In particular, the thermally conductive elastic sheet 31 is formed in an L-shaped cross section, and the heat from not only the rear surface of the mounting substrate 21 but also the lower surface of the mounting substrate 21 passes through the thermal conductive elastic sheet 31. Since it can be made to go out, the heat accumulated in the mounting board 21 can be transmitted to the heat sink board 5 efficiently.

As shown in FIG. 10, the thickness w of the vertical portion of the thermally conductive elastic sheet 31 is slightly thicker than the distance between the mounting substrate 21 and the heat sink substrate 5. By doing so, the vertical portion of the thermally conductive elastic sheet 31 is press-fitted without a gap between the mounting substrate 21 and the heat sink substrate 5.

On the other hand, the thickness h of the horizontal portion of the thermal conductive elastic sheet 31 is also slightly thicker than the distance between the horizontal portions of the mounting substrate 21 and the heat sink substrate 5. By doing so, the horizontal portion of the thermally conductive elastic sheet 31 is press-fitted without a gap between the lower surface of the mounting substrate 21 and the horizontal portion of the heat sink substrate 5.

In addition, it is preferable that at least the bottom surface of the mounting substrate 21 is subjected to abrasive cutting.

Thereby, the unevenness | corrugation of the lower end surface of the mounting board 21 can be made almost, and it can adhere to the thermally conductive elastic sheet 31. FIG.

In particular, by polishing, glass debris and resin debris generated at the ridges of the lower end surface of the mounting substrate 21 can be excluded, so that the air layer between the mounting substrate 21 and the thermally conductive elastic sheet 31 can be prevented. Prevention and heat radiation can be performed efficiently.

In addition, the shading effect caused by the glass dregs and the resin dregs generated from the cut surface of the mounting substrate 21 adhered to the light emitting surface of the LED light source 2 can be prevented, so that the light of the LED light source 2 can be utilized to the maximum. .

Next, the structure of another thermally conductive member, which is effective when used together with the thermally conductive elastic sheet 31, will be described.

11 is a schematic cross-sectional view of the liquid crystal display device of the present invention. The same number is attached | subjected to the same member as FIG. Hereinafter, different parts from FIG. 1 will be described.

Even if the thermally conductive elastic sheet 31 is formed in a pressure contact state in which the thermally conductive elastic sheet 31 is sandwiched between the mounting substrate 21 and the heat sink substrate 5 using a rubbery sheet material having elasticity, There is a fear that a layer of air may be generated on the contact surface between the mounting substrate 21 and the thermally conductive elastic sheet 31 and the contact surface between the thermally conductive elastic sheet 31 and the heat sink substrate 5.

This is because the contact surface where the mounting substrate 21 and the heat sink substrate 5 are in contact with the thermally conductive elastic sheet 31 is not a completely flat surface, and minute unevenness is not avoided, and the thermally conductive elastic sheet 31 is also avoided. This is because the clamping state of the c) is changed by an external impact or the like.

In order to prevent the formation of the air layer due to this, fluidity is high on the contact surface of the thermal conductive elastic sheet 31 and the mounting substrate 21 and the contact surface of the thermal conductive elastic sheet 31 and the heat sink substrate 5. The adhesive 17 or the fluid 17 with low fluidity is interposed.

When the contact surface of the thermally conductive elastic sheet 31 and the mounting substrate 21 and the contact surface of the thermally conductive elastic sheet 31 and the heat sink substrate 5 are fixed by the high fluidity adhesive 17, the LED light source 2 Heat is easily transferred to the heat sink substrate 5.

As a highly fluid adhesive 17, for example, a high thermal conductive adhesive (for example, a thermally conductive adhesive SE4420 manufactured by Toray Dow Corning Silicone Co., Ltd.) or an adhesive tape [for example, a thermal conductive adhesive tape No.8805 manufactured by Sumitomo 3M Co., Ltd.] You can use

In addition, the fluid 17 having low fluidity is made of, for example, a fat or oil component and fine ceramic particles having a high thermal conductivity (called a thermal conductivity compound).

Due to the presence of the fluid 17, corresponding to the minute unevenness of the mounting substrate 21 and the heat sink substrate 5, the holding component of the fluid 17 is impregnated to remove the minute air layer. As a result, the contact state between the mounting substrate 21 and the thermally conductive elastic sheet 31 and the contact state between the thermally conductive elastic sheet 31 and the heat sink substrate 5 are reliably improved, and the mounting substrate 21 is removed from the mounting substrate 21. Through the thermally conductive elastic sheet 31, the heat sink substrate 5 can be thermally conducted efficiently.

Therefore, the heat generated by the LED light source 2 is effectively radiated to the outside, and since the heat generated by the LED light source 2 or the mounting substrate 21 is hardly accumulated, the temperature rise of the LED light source 2 and its surroundings is effective. Can be suppressed.

Next, another member which is preferably used together with the thermally conductive elastic sheet 31 will be described.

12 is a schematic sectional view of a liquid crystal display device of the present invention according to another embodiment. The same number is attached | subjected to the same member as FIG. Hereinafter, different parts from FIG. 1 will be described.

In this embodiment, the thermally conductive elastic member 20 is provided in a state of being in contact with the mounting surface of the LED light source 2 of the mounting substrate 21.

13 is a perspective view of the thermally conductive elastic member 20.

The thermally conductive elastic member 20 has an elongated plate shape substantially corresponding to the mounting substrate 21.

The thermally conductive elastic member 20 is provided with a window opening 20a for accommodating the LED light source 2 mounted on the mounting substrate 21.

The thermally conductive elastic member 20 having such a shape is disposed on the LED mounting surface of the mounting substrate 21. In this case, the LED light source 2 mounted on the mounting substrate 21 may be positioned in the opening portion 20a and press-fitted.

14, the perspective view of the mounting board 21 which mounted the LED light source array to which the thermally conductive elastic member 20 was applied is shown.

As shown in FIG. 12, the thermally conductive elastic member 20 is sandwiched between the light incident side end surfaces of the mounting substrate 21 and the light guide plate 3.

Since the thermally conductive elastic member 20 is substantially present around the LED light source 2, it is emitted from the LED light source 2 to the periphery of the LED light source 2 and the mounting surface side of the mounting substrate 21. All of the heat is received by the thermally conductive elastic member 20, and can escape to the light guide plate 3 or the mounting substrate 21.

In particular, since the heat of the LED light source 2 is transmitted most quickly from the terminal portion 23c formed in the LED container 23b through the metal driving wiring 24 formed on the mounting substrate 21, the thermally conductive elastic member If the 20 is directly in contact with the metal driving wiring 24, the metal pattern of the mounting substrate 21, and the terminal portion 23c, the effect of heat radiation is increased.

In addition, since the heat sink can be directly radiated to the heat sink substrate 5 through the lower end surface of the thermally conductive elastic member 20, the effect of heat radiation is large.

Therefore, the heat generated by the LED light source 2 is effectively radiated to the outside, and it is difficult to accumulate in the LED light source 2 or the mounting substrate 21, so that the temperature rise of the LED light source 2 and its surroundings is effective. Can be suppressed.

Here, the thicknesses of the thermally conductive elastic member 20 and the thermally conductive elastic sheet 31 will be described.

It is important to make the thickness of the thermally conductive elastic member 20 slightly thicker than the design interval between the mounting surfaces of the mounting substrate 21 and the light guide plate 3, that is, the mounting height of the LED light source 2.

In addition, the thickness of the thermally conductive elastic sheet 31 is also slightly thicker than the design interval between the mounting substrate 21 and the heat sink substrate 5.

By setting the thickness in this way, since both the thermally conductive elastic members 20 and 31 have elasticity, the mounting substrate 21 on which the LED light source 2 is mounted is disposed between the light guide plate 3 and the heat sink substrate 5. It is press-contacted and can hold | maintain the mounting board 21 stably.

In addition, even if a minute unevenness is present on the end surface of the light guide plate 3, the front and rear surfaces of the mounting substrate 21, and the surface of the heat sink substrate 5, minute unevenness is absorbed.

As a result, almost no air layer is interposed between the light guide plate 3, the thermally conductive elastic member 20, the mounting substrate 21, the thermally conductive elastic sheet 31, and the heat sink substrate 5. Surface contact.

At the same time, by making the thermally conductive elastic members 20 and 31 elastic, the shock can be absorbed by the thermally conductive elastic members 20 and 31 even when an external shock is applied to the liquid crystal display device. . Therefore, the impact is not transmitted directly to the mounting substrate 21, and there is no positional displacement of the mounting substrate 21, the mounting substrate 21 itself is broken, or the LED light source 2 is no longer separated. .

15 is a schematic sectional view of a liquid crystal display device of the present invention according to another embodiment. The same number is attached | subjected to the same member as FIG. Hereinafter, different parts from FIG. 1 will be described.

In this embodiment, the mounting surface on which the LED light source 2 of the mounting substrate 21 is mounted, the rear surface opposite to the surface, and the lower surface of the mounting substrate 21 perpendicular to the surface are in contact with each other. A thermally conductive elastic member 32 having a cross-section (U) shape is provided.

16 shows an example of the thermally conductive elastic member 32 in a perspective view.

As shown in FIG. 16A, the thermally conductive elastic member 32 includes a first portion 32a which is fitted to the rear surface of the mounting substrate 21 and the heat sink substrate 5, and the mounting substrate 21. And a second portion 32b to be fitted to the LED mounting surface and the light guide plate 3 of the LED, and a third portion 32c disposed between the bottom surface of the mounting substrate 21 and the heat sink substrate 5.

The thermally conductive elastic member 32 has a cross-sectional shape (U) shaped open at the upper side by looking at the left and right sides of the drawing by the first portion 32a, the second portion 32b, and the third portion 32c. It is.

A plurality of openings 32d are formed in the second portion 32b corresponding to the position of the LED light source 2 mounted on the mounting substrate 21.

Although the opening part 32d has the upper side open, in order to arrange | position the mounting board 21 in this thermally conductive elastic member 32, it is from the upper side between the 1st site | part 32a and the 2nd site | part 32b. The LED light source 2 may be positioned below the opening 32d and press-fitted.

At this time, the contact surface of the thermally conductive elastic member 32 and the mounting substrate 21, the contact surface of the thermal conductive elastic member 32 and the heat sink substrate 5, and the contact surface of the heat sink substrate 5 and the light guide plate 3 are provided. In order to improve thermal conductivity, it is preferable to interpose the adhesive 17 having high fluidity or the fluid 17 having low fluidity as described above.

16B and 16C show another example of the thermally conductive elastic member 32.

FIG. 16B is an example in which the opening portion 32d formed in the second portion 32b corresponding to the LED light source 2 has a window shape.

In this case, since the thermally conductive elastic member 32 is substantially present on four side surfaces of the LED light source 2, all of the heat released from the surroundings of the LED light source 2 is thermally conductive elastic member 32. ), And may escape to the heat sink substrate 5 or the light guide plate 3.

Further, in arranging the mounting substrate 21 on the thermally conductive elastic member 32, the gap between the first portion 32a and the second portion 32b is widened from the upper side to mount the mounting substrate 21 in this state. ) From the top.

In addition, the thermally conductive elastic member 32, as shown in Fig. 16 (c), has a cross-section (U) shape in contact with the LED mounting surface, its rear surface, and the upper and lower end surfaces perpendicular to the surface of the mounting substrate 21. It may be a shape.

In the thermally conductive elastic member 32 of FIG. 16C, a fourth portion 32e is further provided on the upper surface side.

Moreover, the opening part 32d which the LED light source 2 exposes is formed in the position which splits the 2nd site | part 32b in the height direction.

In this case, the mounting substrate 21 is inserted into the thermally conductive elastic member 32 having a cross-section (U) shape from the side.

Further, in arranging the mounting substrate 21 on the thermally conductive elastic member 32, the opening 32d formed in the second portion 32b is opened in the vertical direction, and the mounting substrate 21 is disposed in this state. . Alternatively, the mounting substrate 21 may be press-fitted from the side surface of the thermally conductive elastic member 32.

In the structure of FIG. 16C, since four surfaces of the mounting substrate 21 are substantially covered with the thermally conductive elastic member 32, heat conduction efficiency can be improved.

In addition, by the case body 4 (see FIG. 1) of the liquid crystal display device, the thermally conductive elastic member 32 can be sandwiched from the upper surface side. Since the mounting substrate 21 is covered with four surfaces by the thermally conductive elastic member 32, it is excellent in heat dissipation and impact resistance.

The thickness of the thermally conductive elastic member 32 is described. The thermally conductive elastic member 32 compares the external dimension of the thermally conductive elastic member 32 with the internal dimension of the heat sink substrate 5 in order to press-fit the mounting substrate 21 and the heat sink substrate 5. Just make it slightly larger.

Since the thermally conductive elastic member 32 is elastic, minute unevennesses on the surfaces of the mounting substrate 21 and the heat sink substrate 5 are absorbed, and the mounting substrate 21 and the thermal conductive elastic member 32 are also absorbed. The thermally conductive elastic member 32 and the heat sink substrate 5 are securely in close contact with each other with no air layer interposed therebetween and are brought into surface contact.

In the heat sink substrate 5 which is in contact with the outer surface of the thermally conductive elastic member 32, the curved surface R may occur at the inner corner of the heat sink substrate 5 during metal distortion or metal press processing. It is absorbed by the elastic characteristic of the thermally conductive elastic member 32.

In addition, when it cannot absorb by an elastic characteristic, C can chamfer the outer corner part of the thermally conductive elastic member 32 which contacts this inner bending part, and can let this curved surface R escape, and it is thermally conductive. The elastic member 32 and the heat sink substrate 5 are in close contact with each other and are in surface contact with each other.

You may provide a metal case on the outer surface of the thermally conductive elastic member 32 demonstrated above.

17A to 17C are perspective views showing the shape of the metal case 33 surrounding the thermally conductive elastic member 32.

The outer surface of the heat conductive elastic member 32 of cross-sectional shape (U) shape mentioned above is coat | covered with these metal cases 33. As shown in FIG.

The thermally conductive elastic member 32 and the metal case 33 having a cross-sectional shape (U) shape are in close contact with each other on the contact surface. Similar to the thermal conductive elastic member 32, the metal case 33 is provided with a notch portion 33a through which the light emitting surface of the LED light source 2 is exposed.

In addition, the metal case 33 also has the effect of improving the utilization efficiency of the LED light source. Specifically, after the light enters the light guide plate 3 from the LED light source 2, the metal reflection plate provided on the end surface of the light guide plate 3 without being emitted from the light guide plate 3 to the liquid crystal display panel 1 side ( There is light reflected by R) and returned to the end surface side of the LED light source 2 (see FIG. 15).

At this time, if the thermally conductive elastic member 32 is disposed on the end face of the light guide plate 3, the thermally conductive elastic member 32, which is gray to black, absorbs such light, and the light is lost. .

Therefore, by interposing the metal case 33 on the outer surface of the thermally conductive elastic member 32, the light can be returned to the light guide plate 3 by the metal case 33, and the light can be effectively used.

In FIGS. 17A to 17C, the metal case 33 is formed by metal processing so as to have a cross-section (U) shape, but for example, a thermally conductive elastic member having a cross-section (U) shape. It is good also as a structure which encloses the whole (32), and a cross section sphere shape.

In addition, it is preferable to bring the air layer between the thermally conductive elastic member 32 and the metal case 33 so that the air layer does not enter. For example, an adhesive (for example, heat conductive adhesive tape No. 8809 made by Sumitomo 3M Co., Ltd.) may be filled between the thermally conductive elastic member 32 and the metal case 33.

In addition, the metal case 33 may be fixed to the heat sink substrate 5 using a thermally conductive adhesive, so that heat of the thermally conductive elastic member 32 is easily transferred to the heat sink substrate 5. In addition, when the metal case 33 and the heat sink substrate 5 are integrally formed, heat of the metal case 33 is transferred directly to the heat sink substrate 5.

As the thermally conductive adhesive, for example, Toray Dow Corning Silicone Co., Ltd. is a thermally conductive adhesive SE4420.

18 is a schematic sectional view of a liquid crystal display device of the present invention according to another embodiment. The same number is attached | subjected to the same member as FIG. Hereinafter, different parts from FIG. 15 will be described.

In this embodiment, the second portion 32b of the thermally conductive elastic member 32 is in close contact with the end surface of the light guide plate 3.

Heat emitted around the LED light source 2 or heat on the mounting surface side of the mounting substrate 21 is directly transmitted from the second portion 32b of the thermally conductive elastic member 32 to the end surface of the light guide plate 3. Therefore, the light guide plate 3 can exit. In addition, heat can escape to the heat sink substrate 5 through the third portion 32c. In addition, it is transmitted to the first portion 32a positioned between the mounting substrate 21 and the end surface of the light guide plate 3 through the third portion 32c, and is transferred from the first portion 32a to the heat sink substrate 5. You can get out.

Here, about the first portion 32a and the second portion 32b of the thermally conductive elastic member 32, as described above, the design interval between the mounting substrate 21 and the heat sink substrate 5, the mounting substrate. The thickness is slightly thicker than the design interval between the 21 and the light guide plate 3. As a result, pressure contact is securely sandwiched between the second portion 32b, the mounting substrate 21, and the end surface of the light guide plate 3, and the air layer can be efficiently escaped without entering the air layer therebetween.

19 is a schematic cross-sectional view of a liquid crystal display device according to another embodiment of the present invention. The same number is attached | subjected to the same member as FIG. Hereinafter, different parts from FIG. 1 will be described.

In this embodiment, the heat sink substrate 5 is substantially planar, and the mounting substrate 21 is provided on the horizontal plane of the heat sink substrate 5.

In addition, an LED container 23b of the LED light source 2 is mounted on the mounting substrate 21 with one of its side surfaces as the LED mounting surface.

Therefore, the light emission direction of the LED light source 2 becomes a direction parallel to the mounting surface of the mounting board 21, as shown in FIG.

In the LED light source 2, the upper surface and the rear surface (the surface opposite to the light emitting surface) are covered with the thermally conductive elastic member 34.

As shown in FIG. 21, this thermally conductive elastic member 34 has the shape which formed the opening part 34a opened downward which accommodates the LED light source 2, and LED joined to the mounting substrate 21. As shown in FIG. It is formed so as to surround four surfaces except one side and the light emitting surface of the light source 2.

The thermally conductive elastic member 34 is pressed by the upper case body 4 toward the mounting substrate 21, that is, from the upper side in FIG.

At the same time, the upper case body 4 and the heat sink substrate 5 are pressed together toward the end surface of the light guide plate 3 from the back side of the LED light source.

Therefore, the heat of the LED light source 2 is transferred to the upper case body 4 and the heat sink substrate 5 through the convex portion 32b of the thermally conductive elastic member 34 present around the LED light source 2. Can get out of

In this way, the heat generated by the LED light source 2 is effectively radiated to the outside, and since the heat generated by the LED light source 2 or the mounting substrate 21 is hardly accumulated, the temperature rise of the LED light source 2 or its surroundings is increased. It can be effectively suppressed.

The opening 34a of the thermally conductive elastic member 34 shown in FIG. 21 has a window-shaped opening corresponding to the plurality of LED light sources 2, but the mounting substrate is mounted on the thermally conductive elastic member 34. In the case of arranging 21, the LED light source 2 mounted on the mounting substrate 21 may be placed in the opening 34a and press-fitted.

Here, the thickness of the thermally conductive elastic member 34 is made slightly thicker than the design interval between the mounting substrate 21 and the upper case body 4, and the opening portion 34a is equivalent to the mounting thickness of the LED light source 2. It is good to make thickness.

By optimizing the thickness of the thermally conductive elastic member 34 in this manner, the thermally conductive elastic member 34 can be placed in close contact with the mounting surface of the mounting substrate 21 and the upper surface of the LED light source mounted on the mounting substrate 21. have.

Here, it is important that the thermally conductive elastic member 34 has elasticity. This absorbs the warpage and the uneven shape of the mounting substrate 21 and the heat sink substrate 5, and the heat conductive elastic member 34, the mounting substrate 21, the heat sink substrate 5, and the upper case body ( 4) can be reliably in close contact and surface contact with almost no intervening air layer.

In addition, since the thermally conductive elastic member 34 forms an opening portion 34a for accommodating the LED light source 2 and the convex portion 34b is in contact with the LED mounting surface of the mounting substrate 21, the light guide plate ( Light other than the direction leading to the end surface of 3) is light-shielded and reflected, and light leakage can be prevented and light utilization efficiency can be improved.

In addition, since the heat of the LED light source 2 is most transmitted from the connection terminal portion 23c through the metal driving wiring 24 formed on the mounting substrate 21, the thermal conductive elastic member 34 is mounted on the mounting substrate 21. The contact with the metal driving wiring 24 or the contact terminal portion 23c causes a large heat dissipation effect.

Next, when installing the LED light source 2 to the mounting board 21, embodiment which improves the thermal conductivity from the LED light source 2 to the mounting board 21 is demonstrated.

In this embodiment, as shown in FIG. 6, the LED light source 2 is provided to the mounting metal film 22 of the mounting substrate 21 through the heat dissipation bonding material 30 having good heat dissipation and adhesiveness. Can be installed.

The effect of having this heat dissipation bonding material 30 interposed between the LED light source 2 and the mounting substrate 21 is as follows.

Usually, the LED light source 2 and the mounting board 21 are only connected using the electroconductive member and the solder in two places of the connection terminal part 23c.

Therefore, heat generated in the LED chip 23a of the LED light source 2 is conventionally transmitted from the LED container 23b to the mounting substrate 21 through the connection terminal portion 23c, and otherwise, It was released to the outside air.

On the other hand, in this invention, the gap | interval (air layer) between the LED container 23b of the LED light source 2 and the mounting board | substrate 21 is eliminated, and the heat radiation bonding material 30 is filled. Thereby, the heat accumulated in the LED container 23b can be efficiently conducted to the mounting metal film 22 of the mounting substrate 21, and the metal film for heat dissipation (through the plurality of metal via holes 27) can be efficiently 26).

In addition, by integrally forming the mounting metal film 22 and the metal film pattern 25, the heat-dissipating bonding material 30 is formed even if the mounting metal film 22 and the metal film pattern 25 are formed separately. By covering so as to cover both, the heat of the LED container 23b can be effectively transmitted to the mounting substrate 21 side, and can be transmitted to the heat radiation metal film 26 using the plurality of metal via holes 27.

As described above, the heat dissipation bonding material 30 is used, the metal via hole 27 is formed from the LED mounting surface side to the opposite surface in the structure of the mounting substrate 21, and the heat transfer effect of these metal via holes 27 is achieved. In order to increase, the mounting metal film 22 and the metal film pattern 25 are provided in the LED mounting surface side, and the metal film 26 for heat dissipation was used on the opposite surface, these metal films 22 and 26 and the metal film. By using a copper-based positive heat conducting material for the pattern 2 and the metal via hole 27, the mounting substrate 21 can reliably and efficiently heat the LED container 23b of the LED light source 2. ) Is transferred to the heat dissipation metal film 26 side, and the temperature rise around the LED chip 21a can be effectively suppressed.

Moreover, in addition to having heat dissipation and adhesiveness as mentioned above, this heat dissipation bonding material 30 preferably has insulation in order to prevent a short circuit between the terminal portions 23c and 23c of the LED light source 2.

In addition, as shown in FIG. 22, the heat dissipation bonding material 30 is extended from the formation region of the mounting metal film 22 except for the region of the metal driving wiring 24 to which the terminal portions 23c and 23c are joined. You may form so that the formation area of the metal via hole 27 may be reached.

In this way, the heat accumulated in the LED container 23b of the LED light source 2 is transferred not only to the mounting metal film 22 but also directly to the metal film 25 through the heat radiation bonding material 30, Via the metal via hole 27, it can be transferred to the heat dissipating metal film 26 on the rear surface side of the mounting substrate 21.

Therefore, the heat accumulated in the LED container 23b of the LED light source 2 can be efficiently escaped to the heat dissipation metal film 26 of the mounting substrate 21.

In order to obtain the same effect, as shown in FIG. 23, the mounting metal film 22 is extended and formed integrally with the metal film pattern 25 (mounting the metal film 22 and the metal film pattern 25). Combined].

Next, another embodiment replacing the heat dissipation bonding material 30 will be described.

In the case of the conventional surface mount type LED light source 2, the terminal portions 23c provided on both sides of the LED light source 2 and the predetermined metal driving wiring 24 of the mounting substrate 21 are positioned at predetermined positions. And a solder reflow method or the like.

A cavity of air with poor thermal conductivity is generated between the LED container 23b that houses the LED chip 23a of the LED light source 2 and the mounting substrate 21.

In this invention, the adhesive agent 35 with high fluidity | liquidity (low viscosity) is supplied to this cavity part by the dispenser application method.

For example, the LED light source 2 is mounted on the mounting substrate 21, and the adhesive 35 is applied and impregnated from one side of the LED storage case. It is important that this high fluidity adhesive 35 is a material with high fluidity which does not corrode metal wiring and the like.

Since the adhesive 35 has high fluidity, the adhesive 35 enters the gap between the LED container 23b and the mounting substrate 21, so that layers of air such as bubbles are not formed integrally, so that the thermal conductivity at this portion is improved. do.

Therefore, the heat generated by the LED light source 2 can be thermally conducted to the mounting substrate 21 through the adhesive 35 and the terminal portion 23c efficiently.

In addition, the mechanical bonding between the LED light source 2 and the mounting board 21 is performed not only by the bonding of the terminal portion 23c but also by the adhesive 35 disposed between the LED container 23b and the mounting board 21. As a result, the mechanical bonding strength between the LED light source 2 and the mounting substrate 21 is also improved, resulting in a liquid crystal display device excellent in impact resistance.

As mentioned above, although embodiment of this invention was described, implementation of this invention is not limited to the said form. For example, in many embodiments up to now, the light guide plate 3 has a thinner end face having a smaller thickness compared with the thickness of the end face on the side where the LED light source 2 is disposed, but the thickness of both end faces is the same. You may make it. In addition, the lower case which also served as the heat sink substrate 5 may similarly have the same dimension in the depth direction of the side surface. In addition, the metal material of the heat sink board | substrate 5 was exposed to the back surface side of a liquid crystal display device by combining the heat sink board | substrate 5 and the lower case, but in order to match the external appearance with the case body 4 of an upper surface side. The heat sink substrate 5 and the lower case body may be constituted by separate members, and the resin may be molded in only the exposed surface of the sheet sink substrate 5.

&Lt; Example 1 >

An aluminum sheet having a thickness of 2 mm was used for the heat sink substrate 5 while using a cross-sectional L-shaped elastic sheet having a heat dissipation characteristic (model number No. 5509 of Sumitomo 3M Co., Ltd.) for the thermal conductive elastic sheet 31. The mounting substrate 21, the thermal conductive elastic sheet 31, and the heat sink substrate 5 were fixed in surface contact.

Here, the thermal conductivity of each of the materials used is 0.45 W / m · K for the mounting substrate 21 made of glass epoxy, 5 W / m · K for the thermally conductive elastic sheet 31, and 236 W / for aluminum of the heat sink substrate 5. m · K.

The heat sink substrate 5 may be magnesium or iron. Incidentally, the thermal conductivity of magnesium is 157 W / m · K, and the iron thermal conductivity is 83.5 W / m · K. When the heat dissipation is poor, the plate thickness increases, but a heat dissipation fin may be provided.

Heat generated along with light emission from the LED light source 2 is thermally conducted to the heat sink substrate 5 to radiate heat through the mounting substrate 21 and the thermal conductive elastic sheet 31. The heat sink substrate 5 is also transferred from the bottom surface of the mounting substrate 21 to the heat sink substrate 5 to radiate heat.

Here, the thermal conductivity of the mounting substrate 21 and the thermally conductive elastic sheet 31 is very low compared to that of the aluminum of the heat sink substrate 5, so that the thermal conductivity of the mounting substrate 21 and the thermally conductive elastic sheet 31 is improved. The method of thinning the thickness of the head) is effective.

Using the 4.7-inch-size liquid crystal display panel 1 as the size of the display area, 16 LED light sources 2 are mounted on the mounting substrate 21, and each LED light source 2 is mounted at room temperature (25 ° C). 20 mA of electric currents were passed through, and the ambient temperature of the LED light source 2 was measured.

As a result, it turned out that the ambient temperature of the LED light source 2 can be suppressed to 40 degreeC, and the estimated lifetime of an LED light source can be extended to about 7500 hours. In addition, the light emission efficiency of the LED light source was small but a tendency of improvement was seen.

On the other hand, when the thermally conductive elastic sheet 31 was removed, it was found that the ambient temperature of the LED light source became 44 ° C, and the estimated life of the LED light source stayed at about 6600 hours.

From the above test result, the thermally conductive elastic sheet 31 is brought into close contact with the mounting substrate 21 and the heat sink substrate 5 to improve thermal conductivity, and heat generated from the LED light source 2 to the heat sink substrate 5. It was found that by efficiently dissipating heat, the heat storage of the LED light source 2 and the mounting substrate 21 can be reduced, and the temperature rise around the LED light source 2 and its surroundings can be reduced.

&Lt; Example 2 >

A fluid 17 (thermally conductive compound) was applied between the mounting substrate 21 and the thermally conductive elastic sheet 31 and between the thermally conductive elastic sheet 31 and the heat sink substrate 5, and was the same as in the first embodiment. The temperature measurement of was performed.

Toray Dow Corning Co., Ltd. SC102 was used for the thermally conductive compound, and the mounting substrate 21, the thermally conductive elastic sheet 31, and the heat sink substrate 5 were fixed in surface contact. The thermal conductivity of the thermally conductive compound is 0.8 W / mK.

The thermally conductive compound is in a clay state in which a high-viscosity fat or oil component is mixed with ceramic fine particles with high thermal conductivity, and the oil-containing component is well fused to cope with unevenness, and through the ceramic particles having high thermal conductivity, Good thermal conductivity.

Using the 4.7-inch-size liquid crystal display panel 1 as the size of the display area, 16 LED light sources 2 are mounted on the mounting substrate 21, and each LED light source 2 is mounted at room temperature (25 ° C). 20 mA of electric currents were passed through, and the ambient temperature of the LED light source 2 was measured.

As a result, it turned out that the ambient temperature of the LED light source 2 can be suppressed to 39 degreeC, and the estimated lifetime of an LED light source can be extended to about 7700 hours. In addition, the light emission efficiency of the LED light source was small but a tendency of improvement was seen.

On the other hand, when the thermally conductive elastic sheet 31 and the thermally conductive compound were excluded, the ambient temperature of the LED light source became 44 ° C., and the estimated lifetime of the LED light source stayed at about 6600 hours.

From the above experimental confirmation results, the thermally conductive compound is interposed between the thermally conductive elastic sheet 31 and the mounting substrate 21 and the thermally conductive elastic sheet 31 and the heat sink substrate 5. It was found that the heat conduction from the LED light source 17 to the heat sink substrate 5 can be further improved by being in full contact.

&Lt; Example 3 >

In addition to the structure of Example 1, the thermal conductivity elastic member 20 was added, and temperature measurement similar to Example 1 was performed.

As the thermal conductive elastic member 20, a plate-shaped elastic sheet having a heat dissipation characteristic (Model No. 5509 of Sumitomo 3M Co., Ltd.) is used, and the light incident side cross section of the mounting substrate 21 and the light guide plate 3 is formed on the surface thereof. Fixed to contact

Heat generated along with light emission from the LED light source 2 is also radiated to the light guide plate 3 via the mounting substrate 21 and the thermally conductive elastic member 20. Therefore, heat transferred from the mounting substrate 21 to the heat sink substrate 5 is radiated from three paths of the mounting surface side, the rear surface side, and the bottom surface of the mounting substrate 21.

Using the 4.7-inch-size liquid crystal display panel 1 as the size of the display area, 16 LED light sources 2 are mounted on the mounting substrate 21, and each LED light source 2 is mounted at room temperature (25 ° C). 20 mA of electric currents were passed through, and the ambient temperature of the LED light source 2 in a backlight was measured.

As a result, it turned out that the ambient temperature of the LED light source 2 can be suppressed to 36 degreeC, and the estimated lifetime of an LED light source can be extended to about 8500 hours. In addition, the light emission efficiency of the LED light source was small but a tendency of improvement was seen.

On the other hand, when the thermally conductive elastic member 20 and the thermally conductive elastic sheet 31 were excluded, the ambient temperature of the LED light source became 44 ° C., and the estimated lifetime of the LED light source stayed at about 6600 hours.

From the above test result, the thermally conductive elastic member 20 and the thermally conductive elastic sheet 31 are brought into close contact with the mounting substrate 21 and the heat sink substrate 5 to improve thermal conductivity, thereby generating heat generated by the LED light source 2. It was found that heat dissipation was efficiently conducted to the light guide plate 3 and the heat sink substrate 5.

Example 4

The thermal conductive elastic member 32 (form No.5509 of Sumitomo 3M Co., Ltd.) having a cross-section (CO) shape having a heat dissipation characteristic in which the thermal conductive elastic member 20 and the thermal conductive elastic sheet 31 are integrated is used. Then, the mounting substrate 21, the thermal conductive elastic member 32, and the heat sink substrate 5 were fixed in surface contact, and the same temperature measurement as in Example 3 was performed.

Then, using the 4.7-inch-size liquid crystal display panel 1 as the size of the display area, 16 LED light sources 2 are mounted on the mounting substrate 21, and each LED light source (at room temperature (25 ° C.)) is used. A current of 20 mA was flowed into 2), and the ambient temperature of the LED light source 2 was measured.

As a result, it turned out that the ambient temperature of the LED light source 2 can be suppressed to 34 degreeC, and the estimated lifetime of an LED light source array can be extended to about 9000 hours. Also, regarding the luminous efficiency of the LED light source array, a slight but improved trend was seen.

On the other hand, when the thermally conductive elastic member 32 was removed, the ambient temperature of the LED light source 2 became 45 degreeC, and it turned out that the estimated lifetime of an LED light source array stays at about 6400 hours.

From the above test results, the thermal conductivity is further improved by using the thermally conductive elastic member 32 having a cross-section (U) shape in close contact with the mounting substrate 21, the heat sink substrate 5, and the light guide plate 3. I knew I could.

In addition, since the thermally conductive elastic member 32 is sandwiched inside the heat sink substrate 5, the mounting substrate 21 can be held at a predetermined position very stably, and from the outside of the case 6 Even if an impact is applied, the shock can be absorbed by the thermally conductive elastic member 32, so that the liquid crystal display device with high reliability can be obtained without causing the position of the LED light source 2 to be displaced or damaged.

&Lt; Example 5 >

As shown in Fig. 19, the mounting substrate 21 is provided on the horizontal surface of the heat sink substrate 5, and one mounting side of the LED container 23b of the LED light source 2 is the LED mounting surface. The temperature measurement similar to Example 1 was performed about the liquid crystal display device mounted in (21).

A plate-shaped elastic sheet (model number No.5509 of Sumitomo 3M Corporation) having heat dissipation characteristics was used for the thermally conductive elastic member 34, and the LED light source 2, the heat sink substrate 5, and the upper case body ( 4) was fixed in surface contact.

Part of the heat generated with the light emission from the LED light source 2 is radiated from the upper medium 4 through the thermally conductive elastic member 34 from the LED container 23b, and thus the side surface of the heat sink substrate 5. It will also radiate heat from.

Using the 4.7-inch-size liquid crystal display panel 1 as the size of the display area, 16 LED light sources 2 are mounted on the mounting substrate 21, and each LED light source 2 is mounted at room temperature (25 ° C). 20 mA of electric currents were passed through, and the ambient temperature of the LED light source 2 in a backlight was measured. As a result, it turned out that the ambient temperature of the LED light source 2 can be suppressed to 36 degreeC, and the estimated lifetime of the LED light source 2 can be extended to about 8500 hours. Moreover, regarding the luminous efficiency of the LED light source 2, the tendency of the improvement was seen small.

On the other hand, when the thermally conductive elastic member 34 was removed, it was found that the ambient temperature of the LED light source became 44 ° C, and the estimated life of the LED light source 2 stayed at about 6600 hours.

From the above test results, it was found that the heat generated by the LED light source 2 can be efficiently radiated to the upper case body 4 and the heat sink substrate 5 through the heat conductive elastic member 34.

Example 6

As shown in Fig. 6, the mounting substrate 21 has a thickness of 0.1 mm, and various metal films 22, 26, metal film patterns 25, and metal driving wirings 24 are disposed on both surfaces thereof. As the metal film, a copper foil having a thickness of 35 μm was used. The metal via hole 27 formed a through hole having a diameter of 0.2 mm, and performed copper plating having a thickness of 25 μm as a plating material on the inner circumference of the through hole.

The heat dissipation metal film 26 of the mounting substrate 21 is thicker from 35 μm to 60 μm in comparison with the other mounting metal film 22 and the metal film pattern 25 on the LED mounting surface side. The heat was made into the structure which is easy to conduction-diffusion. The surface of the metal film of copper material was coat | covered with the solder layer 28 about 20 micrometers thick. As a result, not only the above-described heat dissipation effect is improved, but also soldering and mounting of the LED light source 2 and its driving parts to the mounting substrate 21 are facilitated, and oxidation of the surface of each copper and discoloration and corrosion of copper are performed. Can be prevented.

Since the thermal conductivity of the mounting substrate 21 is very small compared to the metal materials used for the metal films 22 and 26, the metal film pattern 25 and the heat sink substrate 5, the heat conductivity of the heat sink substrate 5 is reduced. In order to improve, the method of making the thickness of a board | substrate infinitely thin is effective. Thin glass epoxy substrates were used for insulation reliability and cost.

As the heat sink substrate 5, a rectangular plate having a thickness of 2 mm and a material of aluminum is used, and is bent in a cross-sectional L shape so as to be in surface contact with the heat dissipating metal film 26 of the mounting substrate 21, and mounted. The board | substrate 21 was screwed in. Here, the thermal conductivity of each material used is 0.45W / m · K for the mounting substrate (gas part of the mounting substrate) made of glass abandonment epoxy resin, 403W / m · K for copper, 236W / m · K for aluminum, and solder. 62.1 W / m * K and heat dissipation bonding material are 0.92 W / m * K.

Heat generated along with light emission from the LED chip 23a of the LED light source 2 is mounted through the heat dissipation bonding material 30 charged and disposed between the LED container 23b of the LED light source 2 and the mounting substrate 21. It is delivered to the substrate 21.

As this heat dissipation bonding material 30, a heat dissipation resin (SE4420 manufactured by Toray Dow Corning Silicon Co., Ltd.) was used.

As a liquid crystal display device, a rectangular liquid crystal display panel 1 having a size of 5.7 inches is used, and five LED light sources 2 are mounted on the mounting substrate 21 in a line, and a current of 250 mA is applied to each LED light source 2. The temperature rise in the LED mounting surface of the mounting board 21 was measured.

As a result, the temperature rise was 25 degrees C or less, and the temperature rise of the back surface side was suppressed to 18 degrees C or less. Compared with the room temperature luminous efficiency of the LED light source including the LED light source 2, the luminous efficiency remained about 2%, and bright display was attained.

On the other hand, in a liquid crystal display device having an LED backlight, the temperature rise around the mounting substrate, especially the LED light source is large, and the temperature rise at the LED mounting surface side of the mounting substrate is 50 ° C. or more, and the luminous efficiency of the LED light source is 4 In addition, the temperature of the mounting substrate becomes 120 ° C or higher, and the damage of the LED light emitting device is also expected.

From the above test results, the mounting structure of the LED light source 2 (via the heat-bonding material 30), the metal films 22 and 26 of the mounting substrate 21, the metal film pattern 25, and the metal via hole conductor ( It was found that the heat conduction can be improved by the various structures of 27), and the heat generated by the LED light source 2 can be efficiently radiated to the heat sink substrate 5.

Example 7

The temperature measurement similar to Example 6 was performed using the adhesive agent 35 instead of the thermal radiation bonding material 30. FIG. Moreover, the thermally conductive elastic member 32 similar to Example 4 was also used.

SE9176L of Toray Dow Corning Silicone Co., Ltd. was used for the adhesive agent 35.

The thermal conductivity of air is 0.024 W / mK, and the adhesive agent 35 illustrated has a large thermal conductivity effect compared to air.

If the adhesive 35 is quickly impregnated in the gap between the LED container 23b and the mounting substrate 21 and is within a range in which air can be removed, it is preferable that the adhesive 35 contains an insulating fine particle material to further improve the thermal conductivity. Do.

Using a 4.7-inch-size liquid crystal display panel 1 as the size of the display area, 16 LED light sources 2 are mounted on the mounting substrate 21, and each LED light source 2 is mounted at room temperature (25 ° C). 20 mA of electric currents were passed through, and the ambient temperature of the LED light source 2 in a backlight was measured.

As a result, it turned out that the ambient temperature of the LED light source 2 can be suppressed to 40 degreeC, and the estimated lifetime of an LED light source can be extended to about 7500 hours. In addition, the light emission efficiency of the LED light source was small but there was a tendency of improvement.

On the other hand, when the adhesive 35 and the thermally conductive elastic member 32 were excluded, the ambient temperature of the LED light source 2 was 44 ° C., and the estimated lifetime of the LED light source stayed at about 6600 hours.

From the test result, the adhesive 35 is applied to the gap between the LED container 23b of the LED light source 2 and the mounting substrate 21, and the thermally conductive elastic member 32 is mounted on the mounting substrate 21 and the heat sink. It was found that by adhering to the substrate 5, the heat conduction was improved, and the heat generated by the LED light source 2 could be efficiently radiated to the heat sink substrate 5.

Claims (10)

Light guide plate;
An LED light source disposed at a light incident surface side of the light guide plate;
A mounting substrate having a mounting surface on which the LED light source is mounted and a rear surface opposite to the mounting surface;
A heat sink substrate having a surface; And
A first heat conductive member formed between the mounting substrate and the heat sink substrate,
An adhesive or fluid is formed between the mounting substrate and the first thermally conductive member and between the first thermally conductive member and the heat sink substrate.
The adhesive or the fluid formed between the mounting substrate and the first thermally conductive member contacts the back surface of the mounting substrate and the first thermally conductive member,
The adhesive or the fluid formed between the first heat conductive member and the heat sink substrate is in contact with the surface of the first heat conductive member and the heat sink substrate,
On the mounting surface of the mounting substrate, a mounting metal film on which the LED light source is mounted is formed,
On the rear surface of the mounting substrate, a heat radiation metal film is formed,
The mounting metal film and the heat dissipation metal film are electrically connected to each other.
delete The light source device according to claim 1, wherein a heat dissipation bonding material is formed between the LED light source and the mounting metal film.
The light source device according to claim 1, wherein said mounting substrate is provided with a metal via hole conductor connecting said mounting metal film and said heat dissipation metal film in a thickness direction of said mounting substrate.
The light source device according to claim 1, wherein a metal film pattern coated with a white film is formed on said mounting surface of said mounting substrate.
The metal driving wiring for supplying a driving current to the LED light source is formed on the mounting surface of the mounting substrate.
And a second thermally conductive member in contact with the metal driving wiring.
The terminal portion of the LED light source is connected via the metal driving wiring and the conductive bonding member,
The second heat conductive member is in contact with the terminal portion of the LED light source.
The light source device according to claim 6, wherein the second thermal conductive member exposes at least the light exit surface of the LED light source to cover the mounting surface of the mounting substrate.
The light source device according to claim 6, wherein the first thermal conductive member and the second thermal conductive member are integrated.
A light source device according to any one of claims 1 and 3 to 9; And
A liquid crystal display panel disposed to face the light guide plate of the light source device; Liquid crystal display comprising a.

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