JP2008299181A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display whose degree of illumination is not lowered by providing an optimal expandable structure of a light guide plate and the like. <P>SOLUTION: The liquid crystal display 1 includes a liquid crystal panel 120, the light guide plate 121 provided on the rear surface thereof, a pair of light source mounting substrates 123 disposed opposite to the right and left side surfaces of the light guide plate and a heat sinks 101 connected to the sides opposite to the light guide plate 121 of the light source mounting substrates 123. First and second reflection sheets 135 and 136 are disposed on the front surface side and the rear surface side of the light guide plate 121, respectively. Rising parts 135b on the right and left sides of the first reflection sheets 135 are made to adhere to the light source mounting substrates 123. The heat sinks 101 have grooves 101d which can receive side end parts 136a of the second reflection sheet 136 on the light guide plate 121 sides. A buffer body 133 is interposed between an optical sheet 134 disposed on the front surface side of the light guide plate 121 and a second frame 138 disposed on the front side of the optical sheet and supporting the liquid crystal panel 120. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a thin liquid crystal display device using a sidelight type backlight.

  Display devices can be broadly classified into light-emitting display devices such as CRT (Cathode Ray Tube) and plasma display panels, and non-light-emitting display devices such as liquid crystal display devices.

  Non-light-emitting display devices that use a reflective light modulation element that adjusts the amount of reflected light according to an image signal and a transmissive light modulation element that adjusts the amount of light transmitted according to an image signal Some use In particular, a liquid crystal display device using a liquid crystal display panel as a transmissive light modulation element and having an illumination device (also called a backlight) on the back is thin and lightweight, so that it can be used as a computer monitor or television receiver (TV). It is adopted as various display devices.

As the display principle of the liquid crystal panel, in addition to the mainstream TN (twisted nematic), IPS (in-plane switching) characterized by a wide viewing angle, MVA (multi-domain vertical alignment), etc. are used. Light is emitted from a backlight installed on the back of the unit, and the liquid crystal panel forms an image by controlling the transmittance of the light emitted from the backlight.
In recent years, there has been a growing demand for higher brightness and wider color reproduction range for these liquid crystal display devices. In addition, with the widespread use of thin TVs, there is an increasing need for TVs that can be wall-mounted.
In order to reduce the thickness of the liquid crystal display device, a sidelight system has been proposed in which the backlight light source is not located on the back side of the liquid crystal panel but arranged on the side.

  In Patent Document 1, a light source is disposed on the side end face side of the light guide plate, a reflection sheet is disposed on the back side of the light guide plate, and the light source is surrounded by a U-shaped reflector except for the side end face (light incident surface) side. The light from the light source is guided to the light incident surface of the light guide plate, and a heat radiating plate is placed around the outside of the side end surface of the reflector and the back side of the reflective sheet, and heat from the light source is transferred from the reflector to the heat radiating plate to dissipate heat. A technique of a sidelight type liquid crystal display device is described (see Patent Document 1 and FIG. 1). Here, the side end surface is a surface facing left and right outside toward the display screen of the liquid crystal display device, and the back surface is a surface opposite to the display screen side of the liquid crystal display device.

In Patent Document 2, an LED (Light Emitting Diode) is used as a light source in a side-light type liquid crystal display device, and an L-shaped L-type heat conduction is performed on a light source mounting substrate through a heat conduction sheet in order to remove heat generated by the LED. The structure which connects to a member, and also transfers heat to a heat sink from an L-type heat conducting member to dissipate heat is described (see Patent Document 2, FIGS. 39 to 41). Patent Document 2 describes a configuration in which a heat conductive reflector is arranged around an LED and fixed to a light source mounting substrate (Patent Document 2, FIG. 48).
Patent Document 2 below describes a configuration in which an LED is used as a light source and a sidelight.

JP 2003-114431 A JP 2006-156324 A

However, in the prior art described in Patent Document 1, the reflector is interposed between the light source and the heat radiating plate, and the heat resistance in heat transfer from the light source to the heat radiating plate is high, and the heat from the light source is efficiently obtained. There was a problem that heat could not be dissipated.
In the prior art described in Patent Document 2, a heat conductive reflector is disposed so as to surround each LED, and the entire LED array on the light source mounting substrate is covered with a transparent resin and molded into a lens. In such a configuration, such a configuration cannot be adopted, and if the configuration of the reflector as in Patent Document 1 is adopted, the same heat dissipation efficiency problem as described above occurs.

  Further, when the light guide plate expands due to heat from the light source and warps, the optical axis shifts and the illumination intensity of the backlight decreases, and the first reflection sheet and the first reflection sheet disposed on the front side and the back side of the light guide plate There is a problem that the reflection sheet 2 is expanded and contracted by the expansion and contraction of the light guide plate and light leakage occurs.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a liquid crystal display device that does not reduce the degree of illumination by providing an optimal stretchable structure such as a light guide plate. It is in.

In order to solve the above-described problems, a first invention includes a liquid crystal panel, a light guide plate disposed on the back surface of the liquid crystal panel, a pair of light source mounting substrates disposed opposite to both side surfaces of the light guide plate, and a light source mounting substrate. A plurality of light sources mounted on the surface of the light guide plate and a back cover disposed on the back side of the light guide plate, and the pair of light source mounting substrates is disposed in the left-right direction with respect to the display screen of the liquid crystal panel In the device
A heat sink provided on the surface of the light source mounting substrate opposite to the light guide plate, and a front surface side of the light guide plate side covering at least the left and right edges of the light guide plate, and the display area portion of the liquid crystal display device being opened 1 and a plate-like second reflection sheet disposed on the back side adjacent to the light guide plate, and a portion covering the left and right end side edges of the first reflection sheet is a light source mounting substrate. And is bent in an L shape and is bonded to the surface of the light source mounting substrate on the light guide plate side.

  According to the first aspect, since the heat sink is disposed on the light source mounting substrate, the heat from the light source is efficiently transferred from the light source mounting substrate to the heat sink. Further, since the first reflection sheet is bonded to the light source mounting substrate, it is prevented that the left and right ends of the first reflection sheet are separated from the surface of the light source mounting substrate on the light guide plate side due to thermal expansion of the light guide plate. it can.

  The second invention is characterized in that, in addition to the configuration of the first invention, an expansion / contraction absorbing portion is provided on the outer side of the left and right end sides of the region overlapping the left and right end side edge portions of the light guide plate.

  According to the second invention, since the expansion / contraction absorption part is provided, even if the first reflection sheet expands / contracts in the left / right direction due to the expansion / contraction of the light guide plate, the light absorption board is absorbed by the expansion / contraction absorption part. It can be prevented that the bonded portion is separated.

  In the third aspect of the invention, in addition to the configuration of the second aspect of the invention, the left and right end side edges of the first reflective sheet further extend to the front side in parallel with the light guide plate side surface of the light source mounting substrate. The heat sink is fixed on the front side of the liquid crystal panel.

  According to the third aspect of the invention, there is a heat insulating effect that does not transmit the heat transferred to the heat sink to the front side of the liquid crystal panel.

4th invention mounts in the surface at the side of the light guide plate of a liquid crystal panel, the light-guide plate arrange | positioned at the back surface of a liquid-crystal panel, a pair of light source mounting board arrange | positioned facing both sides of a light-guide plate In the liquid crystal display device having a plurality of light sources and a back cover disposed on the back side of the light guide plate, and the pair of light source mounting substrates are disposed in the left-right direction with respect to the display screen of the liquid crystal panel,
A heat sink provided on the surface of the light source mounting substrate opposite to the light guide plate, and a front surface side of the light guide plate side covering at least the left and right edges of the light guide plate, and the display area portion of the liquid crystal display device being opened 1 and a plate-like second reflection sheet disposed on the back side adjacent to the light guide plate, and a side end portion of the second reflection sheet is provided on the light guide plate side surface of the heat sink. It is characterized by providing an acceptable groove.

  According to the fourth invention, since the groove of the heat sink absorbs the expansion and contraction of the second reflection sheet, even if the second reflection sheet expands and contracts in the left and right direction due to the heat expansion and contraction of the light guide plate, It is absorbed by the depth, and it can be prevented that the side end portion of the second reflection sheet interferes with the light source mounting substrate or the light leaks away from the light guide plate side surface of the light source mounting substrate.

5th invention arrange | positions a liquid crystal panel from the front side, at least 1 optical sheet, and a light-guide plate in this order, and a pair of light source mounting board | substrate arrange | positioned facing both the side surfaces of a light-guide plate, It has a plurality of light sources mounted on the light guide plate side surface of the light source mounting substrate and a back cover disposed on the back side of the light guide plate, and the pair of light source mounting substrates is disposed in the left-right direction with respect to the display screen of the liquid crystal panel In the liquid crystal display device
A frame-shaped first frame and second frame sandwiching the liquid crystal panel from the front side and the back side, a heat sink provided on the surface opposite to the light guide plate of the light source mounting substrate, and a front side on the light guide plate side, A first reflective sheet that covers at least the left and right edges of the light guide plate and has an opening in the display area of the liquid crystal display device; and a plate-like second reflective sheet disposed on the back side adjacent to the light guide plate; And a buffer having elasticity and slipperiness is interposed between the second frame and the optical sheet.

  According to the fifth invention, since the buffer body having elasticity and slipperiness is interposed between the second frame and the optical sheet, the buffer body and the optical sheet can be used even when the light guide plate expands and contracts due to heat. It is possible to prevent the optical sheet from being bent or damaged.

According to the present invention, even when the light source cannot be surrounded by a U-shaped reflector, the light from the light source can be efficiently guided to the light guide plate. By arranging a heat sink on the surface, heat from the light source can be efficiently conducted.
Further, when the light guide plate is sandwiched and pressed from the front side and the back side in order to suppress warpage due to thermal expansion, the first reflection disposed adjacent to the light guide plate as the light guide plate expands and contracts. The sheet, the second reflection sheet, and the optical sheet are allowed to expand and contract in the left-right direction.

  As a result, it is possible to provide a liquid crystal display device that does not reduce the degree of illumination by providing an optimal stretchable structure for thermal expansion of the light guide plate.

"overall structure"
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view illustrating a configuration of a liquid crystal display device according to an embodiment of the present invention, and FIG.
It is arrow sectional drawing.

In the present embodiment, as shown in FIG. 1, for the purpose of explanation, the top, bottom, left, right, and front and back surfaces are defined based on the display screen of the liquid crystal panel 120. That is, when the user who watches the liquid crystal display device 1 faces the display screen of the liquid crystal panel 120, the front display screen side is “front” and the back side is “back”, and the right side toward the user is displayed. Is defined as “right” and the left side as “left”.
The liquid crystal display device 1 of the present embodiment includes a liquid crystal panel 120, a light guide plate 121, a light source 124, a light source mounting substrate 123, and a heat sink 101 as main components. As other components, the first frame 137, the first rubber cushion 131, the second rubber cushion 132, the second frame 138, the buffer 133, the optical sheet 134, the first reflective sheet 135, the first 2 reflection sheet 136, third frame 139, and back cover 122.

Next, the arrangement and function of each component will be described from the front side with reference to FIG.
(First frame, liquid crystal panel, and second frame)
The first frame 137 is disposed on the front surface of the liquid crystal panel 120 and has a function as a front cover of the liquid crystal display device 1. The first frame 137 has a shape in which the display area of the liquid crystal display device 1 is opened. The second frame 138 and the first reflective sheet are fixed to screw holes (not shown) provided on the front surface of the housing portion 101a of the heat sink 101 on the front surface of the left and right ends of the opening of the first frame 137. A hole (not shown) for fastening together at 201 is provided.

The liquid crystal panel 120 is disposed on the back side of the first frame 137. The liquid crystal panel 120 has a structure in which liquid crystal is sandwiched between two substrates, and has a function as an optical shutter that controls transmission / blocking of light emitted from the light guide plate 121 by turning on / off the liquid crystal.
The liquid crystal panel 120 has a configuration in which a first rubber cushion 131 and a second rubber cushion 132 having a square frame shape are interposed between a first frame 137 and a second frame 138 having a square frame shape. is there.

Specifically, a first rubber cushion 131 is interposed between the back surface of the opening edge portion of the first frame 137 and the front edge portion of the liquid crystal panel 120. Similarly, the liquid crystal panel 120 A second rubber cushion 132 is interposed between the rear edge and the front edge of the second frame 138 to elastically press the liquid crystal panel 120 from both the front side and the rear side. And supported by the first frame 137 and the second frame 138.
The first and second frames 137 and 138 are made of, for example, a metal plate such as stainless steel or aluminum (Al). The first and second rubber cushions 131 and 132 also have a function as a cushioning material.

(Optical sheet, shock absorber)
The optical sheet 134 is disposed on the back side of the second frame 138 with a square frame-shaped buffer 133 interposed therebetween, and further uniformizes the light emitted from the light guide plate 121 or increases the luminance in the front side direction. Has a directivity-imparting function to improve. In FIG. 1, one optical sheet 134 is representatively displayed, but in FIG. 2, the three optical sheets 134A, 134B, and 134C are arranged in this order from the front side. Here, the optical sheet 134A is a reflection deflecting plate that reflects light having a specific vibration surface of light and transmits others, the optical sheet 134B is a prism sheet that improves luminance in the front side direction, and the optical sheet 134C. Is a diffusion sheet for further uniforming the light in the surface.

  In the present embodiment, the above-described three optical sheets 134A, 134B, and 134C are used in combination as the optical sheet 134. However, the present invention is not limited to this, and one optical sheet has a multilayer structure and has a reflective deflection. An optical sheet having at least two functions of a plate function, a prism function, and a diffusion function may be used to reduce the number of optical sheets 134, or conversely, a plurality of diffusion sheets may be combined.

  It is preferable that the buffer 133 has elasticity, has sliding properties (low friction properties, easy slipping properties) with the optical sheet 134, and does not damage the surface of the optical sheet 134 due to sliding. For example, the inner core is made of urethane sponge and the outer side is covered with a nylon (Ag) coated nylon fiber cloth, and further nickel (Ni) plated, or the surface of silicone (Si) rubber sponge is coated with fluororesin, or The thing covered with the fluororesin tape can be considered.

(First reflective sheet)
The first reflection sheet 135 is a resin sheet and is disposed on the back side of the optical sheet 134 (134A, 134B, 134C).
The first reflection sheet 135 is a square frame-like sheet having a square opening corresponding to the display area of the liquid crystal display device 1, and the opening edge 135 a around the opening rises from the left and right ends to the front side. The surface of the rising portion 135b on the light source mounting substrate 123 side is bonded to the light source mounting substrate 123 with an adhesive or an adhesive member 173 such as a double-sided tape. The rising portion 135b has a fixing portion 135c that extends to the front surface side of the heat sink 101, and further bends and extends to the left and right sides. The fixing screw 201 is located at a position corresponding to a screw hole (not shown) of the housing portion 101a of the heat sink 101 described above. A hole (not shown) through which can be inserted is provided.
The first reflection sheet 135 reflects the light that is not incident on the incident surface 121 a of the light guide plate 121 out of the light emitted from the light source 124 and makes it incident on the incident surface 121 a, and the emission surface of the light guide plate 121 near the light source 124. It has a function for returning the light emitted from 121b to the light guide plate 121 again.
In addition, the exit surface 121b of the light guide plate 121 in the vicinity of the light source 124, that is, the region of the light guide plate 121 that overlaps the left and right side portions of the opening edge portion 135a of the first reflection sheet 135 is described in “1. This corresponds to the “right and left edge portions of the light guide plate”.

In the vicinity of the light source 124, the emitted light from the RGB light source 124 is not sufficiently mixed and uneven, and this portion cannot be used as a display area portion. Therefore, by returning the light in the vicinity of the light source 124 to the light guide plate 121 by the first reflection sheet 135, color uniformity can be achieved and light loss can be reduced.
The first reflection sheet 135 is interposed between the heat sink 101 and the second frame 138, so that the heat is transmitted from the heat sink 101 to the liquid crystal panel 120 through the second frame 138 and the first frame 137. It has the function of a heat insulating material to prevent it.

<< Light guide plate, light source, second reflection sheet, heat sink, etc. >>
The light guide plate 121 is disposed on the back surface of the liquid crystal panel 120. A pair of light source mounting substrates 123 are arranged opposite to the left and right side surfaces of the light guide plate 121. On the light source mounting substrate 123, a plurality of RGB light sources 124, for example, LEDs are mounted in a line in the longitudinal direction (vertical direction). The heat sink 101 is bonded to the light source non-mounting surface of the light source mounting substrate 123, that is, the opposite side of the light guide plate 121 by using a heat conductive adhesive member 171 (see FIG. 2), for example, silver paste. The plate-like second reflection sheet 136 is disposed on the back side of the light guide plate 121.
The detailed configuration and function of each will be described below.

(Light guide plate)
The light guide plate 121 is made of a transparent resin such as acrylic, and has a function of converting light emitted from the light source 124 into a surface light source. The light incident on the incident surface 121 a of the light guide plate 121 propagates by being totally reflected in the light guide plate 121, is scattered by reflection dots (not shown) printed on the back surface of the light guide plate 121, and is emitted from the output surface 121 b of the light guide plate 121. It is taken out to the front side. A lateral space is provided between the incident surface 121a of the light guide plate 121 and a lens 142 of the light source 124, which will be described later, and this is an extension when the light guide plate 121 is irradiated with the light source 124 and thermally expanded. Yes.

(Second reflection sheet)
The second reflection sheet 136 reflects light that is not directly incident on the incident surface 121a of the light guide plate 121 out of the light emitted from the light source 124 and makes it incident on the incident surface 121a, thereby improving the light utilization efficiency. The light that has been scattered by the reflective dots and deviated from the total reflection condition and exited to the back side of the light guide plate 121 is returned to the light guide plate 121 again. For this purpose, the light guide plate 121 is disposed adjacent to the back side, the front side of the side end portion 136 a slides facing the back side end surface of the light source mounting substrate 123, and the side end portion 136 a further includes the heat sink 101. It is inserted into a groove 101d to be described later and set so as not to hit the groove bottom surface 101e.

(light source)
The light source 124 has a function of emitting light for display.
The light source mounting substrate 123 is made of, for example, a ceramic substrate, and mounts the light source 124 and supplies current / voltage to the light source via a wiring pattern formed on the light source mounting substrate 123. The light source mounting substrate 123 also has a function as a reflection plate for efficiently guiding the light emitted from the light source to the light guide plate 121. Further, by using a low thermal resistance ceramic, the heat generated by the light source 124 can be easily conducted to the outside.
The light source mounting substrate 123 is not limited to ceramic, and may be any resin plate as long as it has good light reflection efficiency and high thermal conductivity and electrical insulation.
The light sources 124 arranged in a line in the vertical direction are molded into a substantially semi-cylindrical shape with a transparent resin, and the formed substantially semi-cylindrical transparent resin constitutes the lens 142.

(heatsink)
The heat sink 101 is made of a material such as copper or aluminum having excellent thermal conductivity, and is brought into close contact with the light source mounting substrate 123 by a thermal conductive adhesive member 171 such as a thermal conductive tape or silver paste. It has a function to receive heat well. The heat sink 101 is arranged in parallel to the left and right side edges of the liquid crystal display device 1 and also serves as a structural member of the liquid crystal display device 1. The heat sink 101 extends substantially in the shape of a rectangular parallelepiped housing 101a and L-shaped on the back side, While holding the 3rd flame | frame 139, it is comprised from the holding base part 101b used also as the base part of the fin 101c for heat radiation.
A screw hole (not shown) corresponding to the fixing screw 201 is provided on the front surface side of the housing portion 101a, and the fixing portion 135c of the first reflecting sheet 135, the second frame 138, the first frame is provided on the front surface side. The frames 137 are stacked in order and can be fastened together with the fixing screw 201.
In addition, a screw hole (not shown) corresponding to the fixing screw 201 is provided on the back side of the housing portion 101a so that the back cover 122 can be fixed by the fixing screw 201.

  A groove 101d for receiving the side end portion 136a of the second reflective sheet 136 is provided in the vertical direction on the left and right inner surfaces of the housing portion 101a of the heat sink 101, and between the groove bottom surface 101e and the end surface of the side end portion 136a. There is a space for stretching.

(Third frame)
A third frame 139 is disposed on the back side of the second reflection sheet 136. The third frame 139 is made of, for example, a metal plate such as stainless steel or aluminum (Al). The third frame 139 is held on the front side of the holding base 101b, is pressed to the front side, presses the second reflection sheet 136 to the front side, and further includes the light guide plate 121 and the like disposed on the front side. Pressing to the front side prevents the light guide plate 121 from warping.
The third frame 139 is a rib extending from the upper and lower ends to the front side so as to give rigidity so that the deflection to the back side can be reduced and the reflection sheet 136, the light guide plate 121, etc. can be pressed uniformly. have.

(Back cover)
The back cover 122 is disposed on the back surface of the heat sink 101. As shown in FIG. 2, a space continuous in the vertical direction is provided between the third frame 139 and the back cover 122, and a large number of fins 101 c serving as heat dissipation portions of the heat sink 101 are provided in the space from the holding base portion 101 b. It is growing.
The back cover 122 is made of a resin plate and serves as a protective cover on the back of the liquid crystal display device 1 and a structural member of the liquid crystal display device 1 and also has a function of a heat insulating material that prevents heat conduction from the heat sink 101. is doing.
Ventilation holes 107 are provided on the lower side surfaces of the first frame 137 and the back cover 122 for intake, and on the upper sides of the first frame 137 and the back cover 122, respectively.
In addition, a circuit board 140 is arranged at the center of the left and right of the space between the third frame 139 and the back cover 122 in the vertical direction, and is fixed to the back cover 122.

《Assembly order》
Next, the assembly order of the liquid crystal display device 1 will be described.
(1) The circuit board 140 is fixed to the front side of the back cover 122, and the left and right heat sinks 101 to which the light source mounting board 123 is bonded are fixed to the back cover 122 with fixing screws 201, and the front side faces up. Put it in a state. Next, the third frame 139 is placed on the front surface side of the holding base 101b, and the second reflection sheet 136 is inserted into the groove 101d with the reflection surface facing upward, and the groove 101d. The bottom surface 101e is placed so as to ensure the same allowance for both right and left.
(2) Thereafter, the light guide plate 121 is disposed so as to be in the center of the left and right. Then, the first reflection sheet 135 is overlaid on the light guide plate 121. At this time, an adhesive is applied in advance to a region of the rising portion 135b facing the light source mounting substrate 123, and is pressed and adhered to the light source mounting substrate 123 side. Further, the fixing portion 135c of the first reflection sheet 135 is widened to the front side of the housing portion 101a of the heat sink 101, and is set so as to correspond to a screw hole (not shown) of the heat sink 101.

(3) Next, the three optical sheets 134C, 134B, and 134A are stacked on the first reflective sheet 135 in this order. Further, the buffer 133, the second frame 138, the second rubber cushion 132, the liquid crystal panel 120, and the first rubber cushion 131 are stacked in this order.
(4) Finally, the first frame 137 is placed so as to cover the front edge, the left and right side surfaces, and the top and bottom surfaces of the liquid crystal display device 1 and fixed from the front to a screw hole (not shown) provided on the front surface of the housing 101a. Insert the screw 201 and tighten.
As a result, between the front side of the holding base 101b and the back side of the first frame 137, the first rubber cushion 131, the liquid crystal panel 120, the second rubber cushion 132, the second frame, the buffer 133, The optical sheets 134A, 134B, 134C, the first reflection sheet 135, the light guide plate 121, the second reflection sheet 136, and the third frame 139 are pressed and held.
The first frame 137, the first rubber cushion 131, the liquid crystal panel 120, the second rubber cushion 132, and the second frame 138 are bonded with an adhesive and assembled in advance to form a subassembly. There are many cases.
Further, instead of fixing the circuit board 140 to the front side of the back cover 122, it may be fixed to the back side of the third frame 139.

《Action, effect》
The heat generated by the light source 124 is transferred to the housing 101a of the heat sink 101 on the back surface of the light source mounting substrate 123, and further transferred from the holding base 101b to the fin 101c, and then between the light guide plate 121 and the back cover 122. Heat is dissipated by the air flowing between them. Air flowing between the light guide plate 121 and the back cover 122 flows from the bottom to the top by natural convection, and intake air from the first frame 137 and the vent 107 formed on the lower side surface of the back cover 122 becomes the first frame. 137 and the rear cover 122 are discharged from the vent 107 formed on the upper surface.

The light guide plate 121 is thermally expanded by receiving light from the light source 124 and tends to warp, but is pressed and held between the front side of the holding base 101b and the back side of the first frame 137. Further, it is possible to prevent the light guide plate 121 from warping, and to prevent the light axis from shifting due to the optical axis of the light guide plate 121 being shifted.
Further, when the warpage of the light guide plate 121 is suppressed by the pressing and holding, the first reflection sheet 135 and the second reflection sheet 136 that are stacked adjacent to each other on the front side and the back side of the light guide plate 121 are It is dragged by expansion and contraction due to heat, and expands and contracts at least in the horizontal direction. Further, when the first reflection sheet 135 expands and contracts, the three optical sheets 134 (134A, 134B, and 134C) stacked on the front side of the first reflection sheet 135 are also expanded and contracted at least in the lateral direction. Will receive the power of.

According to this embodiment, the first reflection sheet 135 expands and contracts in the left-right direction and the up-down direction, and the three optical sheets 134 (134A, 134B, and 134C in FIG. 2) arranged on the front side thereof are added thereto. Even if the optical sheet 134 is extended or contracted by dragging, the optical sheet 134 is pressed through the slippery buffer 133, so that the optical axis is prevented from being shifted due to wrinkling or bending of the optical sheet 134. If the optical axis shifts due to wrinkling or bending of the optical sheet 134, the uniformity of the light emitted to the front side is reduced, and uneven display of the liquid crystal display device 1 occurs. Therefore, such display unevenness can be prevented.
Further, since the buffer 133 is an elastic member made of a surface material that is slippery with respect to the optical sheet 134, the surface of the optical sheet 134 is not damaged even if the optical sheet 134 expands and contracts.

Further, since the rising portion 135 b of the first reflection sheet 135 is bonded to the light source mounting substrate 123, the first reflection sheet 135 is not dragged by the expansion and contraction of the light guide plate 121 and is not separated from the light source mounting substrate 123. Therefore, a gap is not generated between the light source mounting substrate 123 and the side end portion of the first reflection sheet 135, and the light from the light source 124 does not leak.
For example, like the liquid crystal display device 1A of the comparative example shown in FIG. 3, the first reflection sheet 135 is arranged on the front surface of the light guide plate 121, and the left and right end surfaces B are set only to contact the light source mounting substrate 123. In this case, the light source mounting substrate 123 is separated by expansion and contraction, and the light from the light source 124 leaks to the front side as shown by the left and right end surfaces B ′. If it does so, the light quantity guide | induced to the entrance plane 121a of the light-guide plate 121 will reduce, and an illumination intensity will fall.

  Further, as shown in FIG. 2, the first reflection sheet 135 has a fixed portion 135 c extending to the front side of the housing portion 101 a of the heat sink 101 and is interposed between the heat sink 101 and the second frame 138. There is a heat insulating effect that blocks heat conduction from 101 to the first frame 137 and the second frame 138, and even if the user touches the metal first frame 137, it does not feel hot.

According to the present embodiment, the second reflecting sheet 136 has a side end portion 136a that slides on the rear side end surface of the light source mounting substrate 123 as shown in FIG. Therefore, even if the second reflection sheet 136 is dragged by the light guide plate 121 and expands or contracts in the left-right direction, the light does not leak away from the light source mounting substrate 123 and no wrinkles occur. .
For example, like the liquid crystal display device 1A of the comparative example shown in FIG. 3, the second reflective sheet 136 is disposed on the back side of the light guide plate 121, and the left and right side end surfaces A are set only to reach the light source mounting substrate 123. The left and right end surfaces A ′ are separated from the light source mounting substrate 123 due to expansion and contraction, and the light from the light source 124 leaks to the back side. If it does so, the light quantity guide | induced to the entrance plane 121a of the light-guide plate 121 will reduce, and an illumination intensity will fall.

<< Modification of Embodiment >>
Next, a modification of the present embodiment will be described with reference to FIGS. The same components as those in the embodiment are denoted by the same reference numerals, and redundant description is omitted.
4 and 5 are cross-sectional views of a liquid crystal display device showing a first modification of the present embodiment.
This modification is different from the embodiment in that the first reflection sheets 135B and 135C have at least an expansion / contraction absorbing portion 135d on the left and right outer sides of the region overlapping the light guide plate 121 of the opening edge portion 135a.
In the example of FIG. 4, the expansion / contraction absorption part 135d is obtained by attaching a wavy flexible ridge to the first reflection sheet 135B in advance to form the expansion / contraction absorption part 135d. In the example of FIG. 5, the expansion / contraction absorption part 135d is obtained by attaching a U-shaped bead to the first reflection sheet 135C in advance to form the expansion / contraction absorption part 135d.
Even if the light guide plate 121 expands and contracts in the left-right direction and the first reflection sheet is dragged in the left-right direction, the expansion / contraction absorbing portion 135d can absorb the expansion and contraction. As a result, the adhesive member 173 does not peel off when contracted, and a good reflection state in the vicinity of the light source 124 is maintained.

It is to be noted that the expansion / contraction absorbing portion 135d is provided not only in the horizontal direction side but also in the vertical direction side of the opening edge portion 135a so as to be continuous and surround the front side of the light guide plate 121. It is easy to cope with.
In the above-described embodiment and its modifications, the description of the processing method of the first reflecting sheets 135, 135B, and 135C and the second reflecting sheet 136 on the upper and lower ends of the light guide plate 121 is omitted. In order to suppress leakage of light from the upper and lower end surfaces of 121, the upper and lower end portions of the first reflecting sheet 135 and the upper and lower end portions of the second reflecting sheet 136 as shown in the longitudinal sectional view of the light guide plate and the reflecting sheet in FIG. And may be adhered by the adhesive member 174.

  In the embodiment and its modification, copper or aluminum is used as the heat sink 101. However, the heat conductivity is not limited to copper and aluminum, and the thermal conductivity is 200 (W / m · K) or more, such as gold, silver, copper, aluminum, or the like. Even in the case of using an alloy whose main component is carbon graphite or carbon graphite, the heat radiation from the heat sink 101 can be discharged to the outside without using the back surface of the liquid crystal display device 1 as a heat radiation means.

  In the embodiment and the modifications thereof, copper or aluminum is used as the fin 101c. However, the thermal conductivity is not limited to copper and aluminum, and the thermal conductivity is 200 (W / m · K) or more, such as gold, silver, copper, aluminum, or the like. Even in the case of using an alloy whose main component is carbon graphite or carbon graphite, the heat radiation from the heat sink 101 can be discharged to the outside without using the back surface of the liquid crystal display device 1 as a heat radiation means.

In addition, in this Embodiment and the modification, although it was set as the structure which the fin 101c for thermal radiation extended from the holding | maintenance base 101b, it is not limited to this.
On the back side of the holding base 101b, another member material for heat transfer and heat dissipation, such as a heat pipe, may be attached to the housing 101a.

1 is a configuration perspective view of a liquid crystal display device according to an embodiment of the present invention. It is XX transverse cross section of FIG. It is a figure explaining the expansion-contraction action of the 1st and 2nd reflective sheet by expansion-contraction of the light-guide plate in the liquid crystal display device of a comparative example. It is a cross-sectional view corresponding to the XX cross-sectional view of FIG. 1 showing a modification of the embodiment. It is a cross-sectional view corresponding to the XX cross-sectional view of FIG. 1 showing a modification of the embodiment. The longitudinal cross-sectional view of a light-guide plate and a reflective sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A Liquid crystal display device 101 Heat sink 101a Housing | casing part 101b Holding base part 101c Fin 101d Groove 101e Groove bottom face 107 Vent 120 Liquid crystal panel 121 Light guide plate 121a Incidence surface 121b Emission surface 122 Back cover 123 Light source mounting substrate 124 Light source 131 First rubber Cushion 132 Second rubber cushion 134, 134A, 134B, 134C Optical sheet 135, 135B, 135C First reflective sheet 135a Open edge 135b Standing part 135c Fixed part 135d Stretching and absorbing part 136 Second reflective sheet 136a Side end part 137 First frame 138 Second frame 139 Third frame 140 Circuit board 142 Lens 171 Thermal conductive adhesive member 173 Adhesive member 174 Adhesive member 201 Fixing screw

Claims (8)

A liquid crystal panel; a light guide plate disposed on a back surface of the liquid crystal panel; a pair of light source mounting substrates disposed opposite to both side surfaces of the light guide plate; and a plurality of light sources mounted on the light guide plate side surface of the light source mounting substrate A light source and a back cover disposed on the back side of the light guide plate, and the pair of light source mounting substrates is disposed in a horizontal direction with respect to the display screen of the liquid crystal panel,
A heat sink provided on a surface of the light source mounting substrate opposite to the light guide plate;
A first reflection sheet that covers at least the left and right edges of the light guide plate on the front side of the light guide plate side, and in which a display area portion of the liquid crystal display device is opened;
A plate-like second reflecting sheet disposed on the back side adjacent to the light guide plate,
The portion of the first reflecting sheet that covers the left and right end side edges extends to the light source mounting substrate, bends in an L shape, and is bonded to the light guide plate side surface of the light source mounting substrate. A characteristic liquid crystal display device.   2. The liquid crystal display device according to claim 1, wherein the first reflecting sheet has expansion / contraction absorbing portions on the outer sides of the left and right end sides of the region overlapping the left and right end side edge portions of the light guide plate.   The left and right end side edges of the first reflection sheet are further extended to the front side in parallel with the surface of the light source mounting substrate on the light guide plate side, and fixed on the front side of the liquid crystal panel of the heat sink. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a liquid crystal display device. A liquid crystal panel; a light guide plate disposed on a back surface of the liquid crystal panel; a pair of light source mounting substrates disposed opposite to both side surfaces of the light guide plate; and a plurality of light sources mounted on the light guide plate side surface of the light source mounting substrate A pair of light source mounting substrates arranged in the left-right direction with respect to the display screen of the liquid crystal panel,
A heat sink provided on a surface of the light source mounting substrate opposite to the light guide plate;
A first reflecting sheet that covers at least the left and right edge portions of the light guide plate on the front side of the light guide plate side, and in which a display area portion of the liquid crystal display device is opened;
A plate-like second reflecting sheet disposed on the back side adjacent to the light guide plate,
A liquid crystal display device, wherein a groove capable of receiving a side end portion of the second reflection sheet is provided on a surface of the heat sink on the light guide plate side.   4. The liquid crystal according to claim 1, wherein a groove capable of receiving a side end portion of the second reflection sheet is provided on a surface of the heat sink on the light guide plate side. 5. Display device. A liquid crystal panel, at least one optical sheet, and a light guide plate are arranged in this order from the front side, and a pair of light source mounting substrates arranged facing both side surfaces of the light guide plate, A plurality of light sources mounted on the surface of the light guide plate, and a back cover disposed on the back side of the light guide plate, wherein the pair of light source mounting substrates are disposed in the left-right direction with respect to the display screen of the liquid crystal panel In the liquid crystal display device
A frame-shaped first frame and a second frame sandwiching the liquid crystal panel from the front side and the back side;
A heat sink provided on a surface of the light source mounting substrate opposite to the light guide plate;
A first reflecting sheet that covers at least the left and right edge portions of the light guide plate on the front side of the light guide plate side, and in which a display area portion of the liquid crystal display device is opened;
A plate-like second reflecting sheet disposed on the back side adjacent to the light guide plate,
A liquid crystal display device, wherein a buffer having elasticity and slipperiness is interposed between the second frame and the optical sheet. A frame-shaped first frame and a second frame sandwiching the liquid crystal panel from the front side and the back side;
At least one optical sheet on the back side of the second frame and on the front side of the light guide plate, and a buffer having elasticity and slipperiness between the second frame and the optical sheet The liquid crystal display device according to any one of claims 1 to 5, wherein a body is interposed. A third frame disposed on the back side of the first reflective sheet;
The heat sink is extended until it reaches between the back panel and the back cover, and a heat radiating portion is connected to the tip of the extended heat sink,
By sandwiching the liquid crystal panel between the first frame and the second frame and screwing the heat sink to the front side of the liquid crystal panel, the third frame is removed from the front side surface of the heat radiating unit. The liquid crystal display device according to claim 6, wherein the liquid crystal display device is pressed and supported.

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