JP4683874B2 - Light source device and liquid crystal display device - Google Patents

Description

  The present invention relates to a liquid crystal display device including a liquid crystal display panel and a backlight, and more particularly to a liquid crystal display device using a light emitting diode (LED) as a light source of the backlight.

  2. Description of the Related Art Conventionally, among liquid crystal display device display methods, transmissive and transflective liquid crystal display devices are configured with a liquid crystal display panel and a backlight that supplies light transmitted to the liquid crystal display panel. In general, a backlight includes a light source and a light guide plate, and a small fluorescent tube called CCFL (cold cathode tube) is used as the light source. In addition, the main surface (front surface) of the light guide plate on the side of the liquid crystal display panel is opposed to correspond to the display area of the liquid crystal display panel, and light is transmitted to the main surface (back surface) opposite to the main surface. A diffusion part that diffuses and reflects is formed on the surface side. The CCFL light source is disposed on the end face of the light guide plate. CCFL light incident from the end face of the light guide plate is transmitted into the light guide plate, diffused and reflected on the back side of the light guide plate, and directed from the light guide plate to the liquid crystal display panel. And is converted from a linear light source to a uniform planar light source and used as a light source for a liquid crystal display device.

  However, in this CCFL light source, Hg (mercury) is sealed in a discharge tube, and ultraviolet rays emitted from mercury excited by discharge strike the phosphor on the CCFL tube wall and convert it into visible light. For this reason, in consideration of the environment, the use of an alternative light source is required by suppressing the use of harmful mercury. Further, in order to light the CCFL, a high-voltage high-frequency lighting circuit is required, and high-frequency noise is generated. Thus, there is a problem that not only a countermeasure against noise is separately required but also low-temperature lighting is difficult.

  Meanwhile, as a new light source, a backlight using a light emitting diode module (LED light source) containing a light emitting diode chip (LED) having a feature of a point light source as a light source has been developed. Backlights using this LED light source (LED backlights) are becoming widespread as backlights for liquid crystal display panels due to lower prices, improved luminous efficiency, and environmental regulations. At the same time, with the increase in brightness and size of liquid crystal display devices (increase in display area), there is an increasing demand for a plurality of LED light sources.

  Therefore, in order to obtain an LED backlight for use in high-brightness and large-sized liquid crystal display panels, the LED light source, which is a point light source, is converted into a planar light source that emits light uniformly (converted into uniform light on the light exit surface of the light guide plate For example, it is necessary to control the material and structure of the diffusion portion on the back surface of the light guide plate and to arrange the LED light source at an optimal position in accordance with the directivity of the LED light source.

  The biggest problem here is that the LED light source and its surrounding temperature rise due to the heat generated by the LED light source, thereby reducing the light emission efficiency and life of the LED light source. Although the LED light source has been improved in luminous efficiency due to recent improvements, the luminous efficiency is about 10% at present, and the remaining 90% is released as heat. That is, in a backlight using an LED as a light source, the generated heat is stored in the LED and the substrate on which the LED is mounted, and as the temperature of the LED and its surroundings rises, the luminous efficiency of the LED itself decreases. As for the lifetime, for example, the estimated lifetime (luminance half-life) at a forward current IF = 20 mA of a top view type LED light source (NSCW455) manufactured by Nichia is about 12000 hours at an ambient temperature of 25 ° C. It can be seen that there is only about 5500 hours at 50 ° C., and that the lifetime becomes shorter as the ambient temperature of the LED increases. Furthermore, the heat generated in the LED can cause damage to the LED and the wiring of the insulating substrate on which the LED is mounted. In addition, if the number of LEDs mounted is increased to increase the brightness of the backlight, the amount of heat generation increases, so this heat generation cannot be ignored further.

As a conventional technique related to heat generated in an LED, for example, as disclosed in Japanese Patent Application Laid-Open No. 2003-281924 (Patent Document 1), a light emitting diode generally has a disadvantage that the light emission efficiency decreases when the junction temperature rises. For example, if the temperature of the GaN junction increases by 1 ° C., the luminous efficiency may decrease by about 1%. In order to suppress the temperature rise of the light emitting diode, the light emitting diode is mounted on one side of the wiring board, which is a linear light source substrate having a power supply terminal, and covers the electrode of the insulating substrate disposed in the box-shaped metal case. 2. Description of the Related Art There is known a radiation device having a heat radiation structure in which a conductive adhesive is filled in a box-shaped metal case except for a light emitting element light emitting surface on a heat radiation insulating resin layer provided.
JP 2003-281924 A

  However, the LED backlight used in the liquid crystal display device and disposed on the back side of the liquid crystal display panel is provided with a metal wiring such as copper on one side of a flexible substrate made of polyimide or polyester or an insulating substrate made of glass epoxy, The LED light source is mounted on the wiring, and the back surface of the insulating substrate (the back surface of the surface on which the LED light source is mounted) is placed in surface contact with the housing or heat sink substrate of the liquid crystal display device, or double-sided adhesive tape is fixed. It was.

  However, in the case of a surface mount type LED light source, the metal connection terminals provided on both sides of the LED light source and the wiring connection terminals of the insulating substrate are aligned in a predetermined position and connected by a solder reflow method, etc. Therefore, since a cavity is generated between the storage case for storing the LED chip of the LED light source and the insulating substrate, and heat conduction between the storage case and the insulating substrate is poor, the heat generated mainly by the LED chip is Heat was radiated to the insulating substrate through the connection terminal. In addition, in the surface contact between the back surface of the insulating substrate and the housing of the liquid crystal display device or the heat sink substrate, the surface contact is insufficient due to the minute unevenness on the surface, and an air layer with extremely low heat conduction is interposed. It has become. Also, in the case of fixing double-sided adhesive tape, since the thermal conductivity of double-sided adhesive tape is small, heat conduction from the insulating substrate to the heat sink substrate is insufficient, and heat is stored in the LED light source or its insulating substrate. Due to the rise, there arises a problem that the light emission efficiency of the LED light source is lowered, and further the light emitting diode chip is damaged in a short time.

  In addition, a technique for suppressing the temperature rise of the LED light source by filling the mounting substrate surface on which the LED light source is mounted with a heat conductive resin has been disclosed. Since heat radiation from the substrate to the heat sink substrate is insufficient, there is still a problem that the luminous efficiency of the LED light source is lowered due to the temperature rise of the LED light source. In particular, in the case where the conductive resin is filled as described above, the number of man-hours for filling the heat conductive resin is large, and it is very difficult to fill and cure without entrapment of bubbles inside.

  The present invention has been devised in view of the above-mentioned problems, and an object of the present invention is to provide a light emitting diode comprising a housing case for housing an LED chip with a simple and inexpensive structure in a liquid crystal display device having an LED backlight. An LED light source that improves the heat conduction between the module and the insulating substrate and reduces the temperature rise of the LED light source, thereby suppressing a decrease in the luminous efficiency of the LED light source, preventing damage to the LED chip, and providing a bright and long-lived liquid crystal display A liquid crystal display device is provided.

  Furthermore, surface contact heat conduction between the insulating substrate and the LCD panel housing or heat sink substrate is improved, heat generated from the LED light source is efficiently conducted to the heat sink substrate, and heat storage of the insulating substrate mounted with the LED light source is reduced. Provided is a liquid crystal display device having an LED light source capable of performing a bright and long-life liquid crystal display by reducing the temperature rise of the LED light source.

The light source device of the present invention includes an LED light source having a light emitting surface and a bottom surface located on the opposite side of the light emitting surface, a light guide plate on which light emitted from the light emitting surface of the LED light source is incident, Between the one main surface on which the LED light source is mounted and the other main surface located on the opposite side of the one main surface, between the bottom surface of the LED light source and the one main surface of the mounting substrate And an adhesive that adheres the bottom surface of the LED light source and the one main surface of the mounting substrate, and a part of the adhesive is exposed to the outside and outside the LED light source. provided by out lamina, the adhesive protruding on the outside of the exposed outside and the LED light source is viewed from
It has an arc shape .

The liquid crystal display device of the present invention includes the light source device described above and a liquid crystal display panel disposed to face the one main surface of the light guide plate in the light source device.

  In the liquid crystal display device of the present invention, a highly fluid adhesive is interposed between the housing case for housing the LED chip and the insulating substrate. That is, heat conduction between the LED module and the insulating substrate can be efficiently performed. This is because, unlike conventional conductive resins, bubbles exist in the resin and do not hinder heat conduction. In addition, the adhesive can be supplied easily and reliably using the capillary action of the adhesive, and the light emitting diode module can be firmly fixed to the insulating substrate.

  As a result, the heat storage of the LED light source and the insulating substrate on which the LED light source is mounted is reduced, and the temperature rise of the LED light source is reduced, thereby suppressing a decrease in the luminous efficiency of the LED light source and preventing damage to the LED light source. A liquid crystal display device having an LED backlight capable of long-life liquid crystal display can be provided.

  In addition, since a heat dissipation sheet for efficiently conducting heat to the heat sink substrate is arranged on the back side of the insulating substrate, it is possible to efficiently diffuse and dissipate heat to the heat sink substrate or case provided in the entire back surface area of the liquid crystal display device. Can do. By pressing and holding a rubber elastic heat dissipation sheet with high thermal conductivity as this heat dissipation sheet, the heat dissipation sheet can be used to deal with minute irregularities on the contact surface of the insulating substrate and the heat sink substrate. Therefore, it is possible to eliminate an air layer with extremely small heat conduction, and to efficiently conduct heat from the LED light source to the heat sink substrate.

  Hereinafter, the liquid crystal display device of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic sectional view of a liquid crystal display device of the present invention. FIG. 2 is a front perspective view as seen from the liquid crystal display panel surface. FIG. 3 shows a back perspective view seen from the back side of the liquid crystal display panel. FIG. 4 shows a perspective view of an insulating substrate in which an LED light source is mounted on the insulating substrate. FIG. 5 shows a perspective view of the heat dissipation sheet.

FIG. 6 is a schematic cross-sectional view of an LED light source that is the LED module of the present invention. FIG. 7 shows a schematic cross-sectional view of another liquid crystal display device of the present invention. FIG. 8 is a schematic sectional view of a liquid crystal display panel.

  The liquid crystal display device of the present invention is mainly composed of a liquid crystal display panel 1, a frame 6, and LED backlights (2-5, 7-10, 18).

  The liquid crystal display panel 1 includes a lower transparent substrate 11 that is the other substrate, an upper transparent substrate 12 that is one substrate, and a liquid crystal that is surrounded by a seal portion 14 between the two transparent substrates 11 and 12. Layer 13 is disposed. Further, for example, a display electrode and an alignment film are formed on the inner surface of the lower transparent substrate 11, and a display electrode and an alignment film are also formed on the inner surface of the upper transparent substrate 12. In FIG. 8, the structure on the inner surface of the lower transparent substrate is simply indicated by reference numeral 15, and the structure of the upper transparent substrate is simply indicated by reference numeral 16.

  The display electrodes constituting the internal structure of the lower transparent substrate 11 and the display electrodes constituting the internal structure of the upper transparent substrate 12 form display pixel regions arranged in a matrix so as to face each other.

  One pixel constituting each display pixel area is a translucent liquid crystal display device in which, for example, in a transmissive liquid crystal display device, the display electrodes are all formed of transparent electrodes and serve as a light transmissive portion that can transmit the light of the backlight. In the display device, a light reflecting portion, part of which is made of a reflective metal film, and a light transmitting portion, which is partly capable of transmitting light from the backlight, are provided side by side. That is, in this transflective liquid crystal display device, external light incident from the display surface side is reflected by the light reflecting portion of the pixel area and returned to the display surface side, and the backlight light is transmitted. The light is given to the display surface side. As a result, when the external light is strong, the display is performed in the reflective mode, and when the external light is weak, the display is performed in the transmissive mode.

  Further, although not shown in the drawing, a polarizing plate, a retardation plate, and, if necessary, a scattering plate are arranged on the outer surface of the lower transparent substrate 11 and the outer surface of the upper transparent substrate 12.

  In order to achieve color display, a color filter corresponding to each pixel region of either the internal structure 15 of the lower transparent substrate 11 or the internal structure 16 of the upper transparent substrate 12 may be formed.

  Further, depending on the display driving method, switching means may be formed in each pixel region of the internal structure 15 of the lower transparent substrate 11 to control display for each pixel region.

  In addition, in one of the upper transparent substrate 12 and the lower transparent substrate 11, for example, a substrate having a large shape, for example, the outer peripheral region of the lower transparent substrate 11, display electrodes and switching among the inner surface structures 15 of the lower transparent substrate 11. A wiring pattern connected to the element may be provided and an input terminal connected to a driving circuit for supplying a predetermined signal and a predetermined voltage to the wiring pattern or an external driving circuit may be provided. Note that the substrate on the side where the wiring pattern is not formed, for example, the display electrode of the upper transparent substrate 12 is connected to the wiring pattern on the lower transparent substrate side via a conductive filler disposed in the space between the substrates 11 and 12. It doesn't matter.

  Examples of the lower transparent substrate 11 and the upper transparent substrate 12 include glass and translucent plastic. The display electrodes forming the internal structures 15 and 16 are made of, for example, ITO or tin oxide which is a transparent conductive material, and the reflective metal film constituting the reflective portion is made of aluminum or titanium. The alignment film is made of a rubbed polyimide resin. In addition, when forming color filters, dyes or pigments are added to the resin to form red, green, and blue color filters for each pixel area, and between the filters and around the pixel area for light shielding purposes. A black resin may be used.

  The lower transparent substrate 11 and the upper transparent substrate 12 are bonded and pressure-bonded via the seal portion 14, and a liquid crystal material made of nematic liquid crystal or the like is injected from a part of the opening of the seal portion 14. Seal the inlet. At the time of bonding, both display electrodes arranged on the transparent substrates 11 and 12 are made to be orthogonal to each other, and the intersection of the display electrodes becomes each pixel region, and this pixel region is aggregated to become a display region.

  In this way, the liquid crystal display panel 1 is configured. An LED backlight is disposed outside the lower substrate 11 which is the other transparent substrate of the liquid crystal display panel 1.

  As shown in FIG. 1, the LED backlight includes an LED light source 7, a light guide plate 4, a lens sheet 2, a diffusion sheet 3, a reflection sheet 5, an insulating substrate 8, a heat dissipation sheet 9, a heat sink substrate 10, and an adhesive 18. ing.

  Then, one main surface (surface from which light is emitted) of the light guide plate 4 is disposed so as to face the display area of the liquid crystal display panel 1.

  The light guide plate 4 constituting the LED backlight is made of a transparent resin substrate, and a light scattering member may be contained in the resin component. On the other main surface of the light guide plate 4, a reflection part is formed that diffuses and reflects light. This reflection part is for radiating light propagating in the light guide plate to one main surface side, and a groove for diffusing and reflecting directly on the other main surface is formed, and further, on the other main surface A coating film having a diffusion / reflection function may be formed.

  The insulating substrate 8 is made of a glass cloth base epoxy resin substrate or a ceramic substrate, and a metal wiring for supplying a predetermined driving current to the LED light source is formed on the mounting surface of the LED light source 7. A plurality of LED light sources 7 (electrodes thereof) are mounted on the metal wiring at a predetermined interval via a conductive member.

  As shown in the cross-sectional view of FIG. 6, the LED light source 7 includes an LED chip 7a having a light emitting portion made of a semiconductor material, an anode electrode, and a cathode electrode, and a storage case 7b made of a heat-resistant resin material or a ceramic material. ing. A mortar-shaped cavity 7d is formed on the surface of the storage case 7b from which light is emitted, and the LED chip 7a is disposed and stored at the bottom of the cavity 7d. The anode electrode and cathode electrode of the LED chip 7a are connected to a terminal portion 7c formed on the outer surface other than the light emitting surface of the storage case 7b. A reflective paint is applied to the inner wall surface of the mortar-shaped cavity, and the cavity is filled with a translucent resin or a fluorescent resin so as to embed the LED chip 7a.

  Next, a heat dissipation structure for heat generated from the LED light source 7 will be described.

First, a plurality of LED light sources 7 having the above-described structure are arranged and mounted in rows on the metal wiring of the insulating substrate 8 at a predetermined interval. The insulating substrate 8 is installed so that the light emitting surface of the mounted LED light source 7 faces the end surface of the light guide plate 4. That is, the surface of the insulating substrate 8 is located on the light guide plate 4 side. The back surface of the insulating substrate 8 faces the metal heat sink substrate 10 or a housing having a heat sink function (referred to as a heat sink substrate in this case). At this time, in the case of the surface mount type LED light source 7, for example, the terminal portions 7c, 7c provided on both sides of the LED light source 7 and predetermined wiring connection terminals of the insulating substrate 8 are aligned at predetermined positions and soldered Connection is made by a reflow method or the like. That is, an air cavity having a poor thermal conductivity is generated between the housing case 7b for housing the LED chip 7a of the LED light source 7 and the insulating substrate 8. In the present invention, the adhesive 18 having high fluidity (low viscosity) is supplied to the hollow portion by a dispenser coating method or the like. For example, it is impregnated from one side of the LED storage case. The highly liquid adhesive 18 is preferably a material that does not corrode metallic wiring or the like.

  Because of such a structure, when the backlight of the liquid crystal display device is driven (the LED light source 7 is driven to light) in order to improve the visibility of the display information on the liquid crystal display panel 1, the light emission and heat However, the heat generated by the LED light source 7 efficiently conducts the LED chip 7a of the LED light source 7 to the insulating substrate 8 through the adhesive 18 and the terminal portion 7c in the gap between the storage case 7b and the insulating substrate 8. Can do. Since this is a highly fluid adhesive 18, no air layer such as bubbles is formed in the adhesive 18 in the gap between the storage case 7 b and the insulating substrate 8. Heat conduction is greatly improved.

  Moreover, since the mechanical joining of the LED light source 7 and the insulating substrate 8 is achieved not only by the joining of the terminal portion 7c but also by the adhesive 18 disposed between the storage case 7b and the insulating substrate 8, the LED The mechanical joint strength between the light source 7 and the insulating substrate 8 is also improved, and a liquid crystal display device excellent in impact resistance is obtained.

  Further, in order to efficiently conduct the heat of the LED light source 7 to the heat sink substrate 10 or the housing, the rubber elastic heat radiation having a high thermal conductivity between the other main surface side of the insulating substrate 8 and the heat sink substrate 10 or the housing. It is desirable to arrange on the sheet 9. It is important that the thickness of the heat dissipation sheet 9 is slightly larger than the gap between the insulating substrate 8 and the heat sink substrate 10. The insulating substrate 8 is fixed to the insulating substrate 8 on which the LED light source 7 is mounted by a protrusion provided on the frame 6.

  In this way, the heat dissipation sheet 9 is pressed and sandwiched between the insulating substrate 8 and the heat sink substrate 10, so that the heat dissipation sheet 9 can be adapted to the minute unevenness of the contact surface between the insulating substrate 8 and the heat sink substrate 10. The air layer (air layer caused by unevenness) having a very low heat conduction can be eliminated, and the heat can be efficiently conducted from the LED light source 7 to the heat sink substrate 10 and provided, for example, in the entire back surface region of the liquid crystal display device. Thus, the heat sink substrate 10 or the housing can be diffused and radiated efficiently.

  Furthermore, the heat transmitted to the insulating substrate 8 is thermally conducted to the heat sink substrate 10 and radiated through the heat radiation sheet 9 without passing through the air layer having poor heat conduction in the middle as described above.

  Therefore, the heat generated in the LED light source 7 is effectively radiated to the outside, and it is difficult for the LED light source 7 and the insulating substrate 8 to store heat. it can.

  These effects are that the display area of the liquid crystal display panel 1 is enlarged, the shape of the light guide plate 4 is enlarged, and a large number of LED light sources are supplied to the insulating substrate 8 in order to supply sufficient light to the enlarged light guide plate 4. The more the 7 is installed, the greater the effect.

FIG. 7 is a sectional structural view of another liquid crystal display device of the present invention. In this embodiment, the casing that is the heat sink substrate 10 of the liquid crystal display device has a substantially rectangular parallelepiped shape, and a flat plate having a substantially uniform thickness of the light guide 4 is used. Thus, by making the shape of a housing into a perfect rectangular parallelepiped shape, it becomes very easy to use part of the housing as a heat sink substrate.

  Model No. 5509 of Sumitomo 3M Co. is used for the heat dissipation sheet 9, aluminum of 2mm thickness is used for the heat sink substrate 10, and SE9176L of Toray Dow Corning Silicone Co. is used for the adhesive 18. The insulating substrate 8, the heat radiation sheet 9, and the heat sink substrate 10 were fixed so as to be in close contact with each other.

  Here, the thermal conductivity of each material used is 0.45 W / m · K for an insulating substrate made of glass epoxy, 5 W / m · K for a heat dissipation sheet, 0.17 W / mK for an adhesive, and aluminum as a heat sink substrate. 236 W / m · K. The thermal conductivity of air is 0.024 W / mK, and the exemplified adhesive has a larger thermal conductivity than air. The adhesive preferably contains an insulating fine particle material or the like to further improve the thermal conductivity as long as the adhesive can be removed from the gap between the LED chip storage case and the insulating substrate.

  Here, since the thermal conductivity of the insulating substrate 8 and the heat radiating sheet 9 is very small as compared with aluminum which is a heat sink substrate, in order to improve the heat conduction, the insulating substrate 8 and the heat radiating sheet 9 are made as thin as possible. The method to do is effective. Further, the heat sink substrate 10 may be magnesium or iron. By the way, the thermal conductivity of magnesium is 157 W / m · K, the thermal conductivity of iron is 83.5 W / m · K, and if the heat dissipation is poor, increase the plate thickness or provide heat dissipation fins. Good.

  Then, using the liquid crystal display panel 1 having a size of 4.7 inches as the size of the display area, 16 LED light sources 7 are arrayed and mounted on the insulating substrate 8, and a current is supplied to each LED light source 7 at room temperature (25 ° C.). The ambient temperature of the LED light source 7 in the backlight was measured at a current of 20 mA. As a result, it was found that the ambient temperature of the LED light source 7 can be suppressed to 40 ° C., and the estimated lifetime of the LED light source can be extended to about 7500 hours. In addition, the luminous efficiency of the LED light source showed a tendency to improve although it was very small.

  On the other hand, when the adhesive 18 and the heat radiating sheet 9 were removed, it was found that the ambient temperature of the LED light source 7 was 44 ° C., and the estimated lifetime of the LED light source was only about 6600 hours.

  From the above experimental confirmation results, the adhesive 18 is applied to the gap between the storage case 7b of the LED chip 7a of the LED light source 7 and the insulating substrate 8, and the heat radiation sheet 9 is brought into close contact with the insulating substrate 8 and the heat sink substrate 10 to conduct heat conduction. By improving and efficiently dissipating the generated heat of the LED light source 7 to the heat sink substrate 10, the heat storage of the LED light source 7 and the insulating substrate 8 is reduced, and the temperature rise of the LED light source and its surroundings is reduced, thereby reducing the LED light source. In this way, a long life and bright liquid crystal display device can be realized.

It is a schematic sectional drawing of the liquid crystal display device of this invention. It is the surface perspective view seen from the liquid crystal panel surface of the liquid crystal display device of this invention. It is the back surface perspective view seen from the liquid crystal panel back surface of the liquid crystal display device of this invention. It is an insulated substrate perspective view which mounted the LED light source on the insulated substrate of the liquid crystal display device of this invention. It is a heat-radiation sheet perspective view of the liquid crystal display device of this invention. It is structural sectional drawing of the LED module (LED light source) used for the liquid crystal display device of this invention. It is a schematic sectional drawing of the other liquid crystal display device of this invention. It is a schematic sectional drawing of the liquid crystal display element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display panel 2 ... Lens sheet 3 ... Diffusion sheet 4 ... Light guide plate 5 ... Reflection sheet 6 ... Frame 7 ... LED light source 8 ... Insulating substrate 9 ... Heat dissipation sheet 10 ... Heat sink substrate 18 ... Adhesive

Claims (3)

An LED light source having a light exit surface and a bottom surface located on the opposite side of the light exit surface;
A light guide plate on which light emitted from the light exit surface of the LED light source is incident;
A mounting substrate having one main surface on which the LED light source is mounted, and the other main surface located on the opposite side of the one main surface;
An adhesive that is positioned between the bottom surface of the LED light source and the one main surface of the mounting substrate, and that adheres the bottom surface of the LED light source and the one main surface of the mounting substrate;
Some of the adhesive is provided out look outside the exposed outside and the LED light source,
The light source device , wherein the adhesive that is exposed to the outside and protrudes outside the LED light source has an arc shape in plan view . A heat sink substrate disposed on the other main surface side of the mounting substrate;
The light source device according to claim 1, further comprising: a heat dissipation sheet disposed between the other main surface of the mounting substrate and the heat sink substrate. The light source device according to claim 1 or 2 ,
A liquid crystal display device comprising: a liquid crystal display panel disposed to face the light guide plate in the light source device.

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