JP2010072262A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display including an edge light type light source equipped with a light source in an end of a display face, and having a satisfactory optical characteristic, by enhancing a light taking-out efficiency and by restraining an optical member from being deteriorated. <P>SOLUTION: This liquid crystal display is provided with a recess spread ranging over from at least an LED light source block up to at least one part of a light guide panel/reflecting sheet, in the end arranged with the LED light source block of a panel frame, and is provided further with a reflection heat insulation member spread ranging over from the end of the LED light source block up to at least one part of the light guide panel/reflecting sheet, and fixed onto the panel frame, in the recess. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention particularly relates to an edge light type liquid crystal display device having a light source at an end portion of a display surface, and has excellent optical characteristics by improving light extraction efficiency and suppressing deterioration of an optical member. The present invention relates to a liquid crystal display device.

  The liquid crystal display device displays an image by controlling light transmittance of a large number of pixels formed on a liquid crystal panel surface. The liquid crystal panel itself does not emit light, and a liquid crystal display device generally called a transmissive type includes a light source called a backlight, and makes light emitted from the backlight incident in a planar shape from the back side of the liquid crystal panel.

  As a form of the backlight, a method in which a large number of light sources are dispersed and arranged on the back side of the liquid crystal panel display surface (hereinafter referred to as a direct method), and a method in which a light source is provided at at least one end of the liquid crystal panel (hereinafter referred to as a “light source”) The edge light method is used.

  The edge light system is advantageous in reducing the thickness of the liquid crystal display device compared to the direct system because the light source is arranged at the end of the liquid crystal panel. However, in the edge light system, a light source that generates a lot of heat is concentrated on the end portion, so that the end portion in the vicinity of the light source of an optical component such as a light source or a light guide plate tends to be hot. These high temperatures cause deterioration of optical characteristics due to thermal factors such as light source life reduction, liquid crystal panel display uniformity deterioration, and light guide plate thermal deterioration, so a cooling structure is needed to suppress them. It becomes. In addition, it is desirable that this cooling structure is easy to assemble at the same time, and light from the light source is efficiently incident on the light guide plate toward the liquid crystal panel, or optical characteristics are deteriorated due to factors other than heat. It is necessary not to cause such side effects.

  As a cooling structure in the edge light system, Patent Document 1 discloses a structure using a cold cathode tube as a light source. According to this structure, the heat generated from the cold-cathode tube light source is diffused by the heat conductive layer provided on the back surface, and the effect of relaxing the high temperature at the end is shown. At this time, a reflective layer is simultaneously formed around the cold cathode tube. According to this structure, light emitted from the cold cathode tube is efficiently incident on the light guide plate while cooling. It has become.

  In Patent Document 2, a structure using a light source in which LEDs (light emitting diodes) are arranged on an array is shown. According to this structure, an LED module in which a large number of LEDs are arranged on an elongated substrate is arranged on a metal P plate bent three-dimensionally. Here, the metal P plate is obtained by printing an insulating layer and a copper foil of wiring on a metal sheet metal, and cools the light source by diffusing heat of the light source on the metal P plate. In addition, since the three-dimensionally bent portion of the metal P plate is provided with a reflecting plate, the light emitted from the LED is efficiently incident on the light guide plate.

Japanese Patent Laid-Open No. 6-51307 JP 2006-310221 A

  As shown in the above two patent documents, a cold cathode tube or an LED (light emitting diode) is generally used as an edge light type light source. Cold cathode tubes are relatively inexpensive and can emit a large amount of light, and are therefore mainly used in large liquid crystal display devices such as televisions and computers. On the other hand, LEDs are mainly used in small liquid crystal display devices such as information terminals and mobile phones that require small mounting and do not require much light.

  However, in recent years, the luminous efficiency of LEDs has been improved, and the application of edge light type LED light sources is also being applied to large liquid crystal display devices. By applying the LED to a large liquid crystal display device, there are the following advantages. First, since the light emitting element of the LED is smaller than the cold cathode tube, the liquid crystal display device can be further reduced in thickness. Secondly, the LED light source is a light source in which a large number of light emitting elements are arranged in a substantially linear shape, and the amount of light can be controlled in units of light emitting elements or in units of a plurality of light emitting elements. Thus, by locally controlling the amount of light according to the conditions of the display image, it is possible to reduce power consumption and improve the overall contrast ratio. Third, high color reproducibility can be obtained by combining red, green, and blue light emitting elements as LED light sources.

  As described above, by using an edge light type LED light source, a large-sized liquid crystal display device capable of outputting a thinner and better image can be realized.

  However, in order to realize a large-sized liquid crystal display device having an edge light type LED light source using the structures shown in Patent Document 1 and Patent Document 2, there are the following problems.

  In the structure shown in Patent Document 1, since a cold cathode tube is used, a reflective layer and a heat conductive layer surrounding the light source can be formed, but this is difficult when an LED light source is used. In other words, since the inside of the cold cathode tube that emits light is very hot, the generated heat can be widely transferred and diffused to the heat conduction layer around the light source mainly by radiant heat transfer, Since the light source emits solid-state light and its temperature is lower than that of the light emitting part of the cold cathode tube, and almost no radiant heat transfer can be expected, heat must be conducted mainly by solid heat conduction.

  Therefore, it is difficult to cool the LED light source simply by replacing the cold cathode tube with the LED light source with the structure described in Patent Document 1. Also, with this structure, it may be possible to fix the LED light source to the reflective layer in some form and diffuse the heat to the heat conductive layer, but in this case, the reflective layer of the portion where the LED light source is fixed becomes a thermal resistance, Since the heat diffusion from the LED light source to the heat conducting layer is hindered, the LED light source cannot be effectively cooled. When the LED light source becomes high temperature, not only the reliability and the element lifetime are shortened, but also the light emission efficiency is lowered. Therefore, even if the reduction in reliability is allowed, the power consumption is increased.

  Furthermore, as the display screen size increases, the light intensity is mounted almost in proportion to the area in order to obtain the same display brightness. The arrangement area of the LED light source which is in the shape increases only in proportion to the length. For this reason, when it becomes a large-sized liquid crystal display device, it is necessary to mount LED elements more densely or to increase the light quantity per LED element, and in any case, the heat generation density in the LED light source portion increases. Therefore, in a large-sized liquid crystal display device, the LED light source portion is likely to be hotter.

  For this reason, in the structure shown in Patent Document 1, even if the reliability of the LED light source is decreased and the increase in power consumption is allowed, the high temperature transmitted to the heat conduction layer is transmitted to the light guide plate during the diffusion process, The edge of the light plate becomes hot. The light guide plate is generally made of acrylic resin with good optical properties and surface-treated, but the resin deteriorates due to deterioration and softening due to high temperatures at the edges, resulting in the optical properties of the light guide plate. Will deteriorate.

  The structure described in Patent Document 2 assumes an LED light source, and cools the LED light source by diffusing heat on a metal P plate. In this case, heat is efficiently transmitted from the LED light source to the metal P plate. However, when the liquid crystal display device is enlarged, the heat generation density of the light source increases as described in Patent Document 1 above, and The cooling performance of the light source becomes insufficient only by thermal diffusion. As a result, the LED light source and the metal P plate become hot. As a result, similar to the structure described in Patent Document 1, the reliability of the light source is reduced and the power consumption is increased. Furthermore, the end portion of the light guide plate becomes high temperature due to the high temperature metal P plate, causing deterioration of optical characteristics.

  As described above, in the structures described in Patent Literature 1 and Patent Literature 2, light emitted from the light source is efficiently incident on the light guide plate, but is applied to a large liquid crystal display device. In this case, the cooling performance of the LED light source is insufficient, which not only decreases the reliability of the light source and increases the power consumption. There was a problem that caused deterioration.

  The object of the present invention is to solve the above-described conventional problems, and to efficiently enter the light emitted from the light source into the light guide plate, and at the same time, effectively cool the LED light source even in a large liquid crystal display device, An object of the present invention is to provide a liquid crystal display device having good optical characteristics that suppresses deterioration of optical characteristics due to heat.

  The object is to provide a liquid crystal panel, an LED light source provided on at least one end of the display surface, an LED light source block equipped with the LED light source, and light from the LED light source provided on the back side of the liquid crystal panel. A liquid crystal display comprising: a light guide plate that guides the liquid crystal panel; a reflection sheet provided on a back side of the light guide plate; and a panel frame that fixes the LED light source block and holds the light guide plate and the reflection sheet from the back side In the apparatus, at the end of the panel frame where the LED light source block is disposed, a concave portion extending from at least the LED light source block to at least a part of the light guide plate / reflective sheet is provided, and the LED light source is further provided in the concave portion. The panel extends from the end of the block to at least a part of the light guide plate / reflective sheet, and the panel It is achieved by providing a fixed end reflector heat insulating member to frame.

  The above-described object is achieved by the end reflective heat insulating member having a reflective surface formed on a surface facing the liquid crystal panel and a heat insulating layer provided on the side fixed to the panel frame.

  Moreover, the said objective is achieved by the said edge part reflection heat insulation member being comprised by the laminated body of the said reflection sheet and a heat insulation member.

  Further, the above object is that the end reflective heat insulating member has a reflective surface formed on a surface facing the liquid crystal panel and a hollow portion formed on at least a part of the side fixed to the panel frame. Achieved.

  Moreover, the said objective is achieved because the said edge reflection heat insulation member is contacting with the said light guide plate and the said reflection sheet in the form which can be slid.

  According to the present invention, the panel frame is provided with a recess that extends to at least a part of the light guide plate and the reflection sheet, and further, the recess extends from the end of the LED light source block to at least a part of the light guide plate / reflection sheet. In addition, by providing an end reflective heat insulating member fixed to the panel frame, even in a large liquid crystal display device, light emitted from the light source can be efficiently incident on the light guide plate, and at the same time, the LED light source can be effectively used. It is possible to provide a liquid crystal display device having good optical characteristics that is cooled to a low temperature and prevents deterioration of optical characteristics due to heat.

  Hereinafter, a liquid crystal display device according to an embodiment will be described with reference to FIGS.

FIG. 1 is a schematic configuration diagram of the liquid crystal display device according to the present embodiment as viewed from the display surface side.
2 is a cross-sectional view taken along the line AA ′ of FIG.
In the scope of the present invention, the vertical direction in FIG. 1 is defined as the vertical direction, and the horizontal direction is defined as the horizontal direction. Further, the liquid crystal panel 3 side in FIG. 2 is defined as the front side, and the back exterior panel 4 side is defined as the back side.

  As shown in FIG. 1, when the liquid crystal display device 1 is viewed from the display surface side, the liquid crystal panel 3 can be seen inside the front exterior panel 2. As shown in FIG. 2, members represented by the light guide plate 11 are laminated on the back side of the liquid crystal panel 3 in order to uniformly guide the light to the back side of the liquid crystal panel. A panel frame 8 is arranged to hold the frame from the back side. The LED substrate 10 on which the light source is mounted is attached to the LED light source block 9, and the LED light source block 9 is fixed to the panel frame 8. On the further back surface of the panel frame 8, electrical circuit boards 5, 6, and 7 are arranged as necessary. Further, a rear exterior panel 4 is disposed on the back surface, and together with the front exterior panel 2, the casing of the liquid crystal display device 1 is formed.

  The electric circuit boards 5, 6 and 7 are, for example, a driver for supplying a current to the LED light source, a signal processing circuit for processing a display signal input to the liquid crystal display device, and a necessary power source from a commercial power source. In the case of a power supply circuit board or a display device such as a television, it is a tuner circuit board, but is not particularly limited.

  The LED substrate 10 on which the LED elements that are light sources are mounted is disposed at both ends in the lateral direction, and light emitted from the light sources is incident from both ends of the light guide plate 11, and the liquid crystal panel from the front surface of the light guide plate 11. 3 is transmitted to form an image.

FIG. 3 shows an enlarged view of the end in FIG. For easy understanding of the drawing, the front exterior panel 2, the rear exterior panel 4, and the electric circuit board are not shown.
A panel gap 14 is provided as a space on the back surface of the liquid crystal panel 3, and a diffusion sheet 12, a light guide plate 11, and a reflection sheet 13 are disposed on the back surface, and are held by the panel frame 8 from the back side. The panel gap 14 has an effect of improving the uniformity of light incident on the liquid crystal panel 3 from the light guide plate 11 and preventing the surface of the diffusion sheet 12 from being damaged when the liquid crystal panel 3 is curved. The diffusion sheet 12 is for increasing the uniformity of light traveling from the light guide plate 11 to the liquid crystal panel 3, and a prism sheet or the like for improving viewing angle characteristics is laminated on this portion as necessary. The reflection sheet 13 reflects the light incident on the light guide plate from the end portion so that the light does not leak to the back side and is directed toward the liquid crystal panel efficiently. The reflection sheet 13 may be, for example, a sheet of PET (polyethylene terephthalate) or PC (polycarbonate) that has a mirror-deposited aluminum coating or a white pigment applied to increase the reflectance.

  The liquid crystal panel 3 is held by the front frame 25 and the light guide plate pressing member 26 via a panel pressing rubber 39. By using the panel pressing rubber 39, the force applied to the liquid crystal panel is relaxed, and the liquid crystal panel is prevented from being damaged. The light guide plate holding member 26 has a role of holding the diffusion sheet 12 and the light guide plate 11 from the front side, and is sandwiched between the panel frame 8 on the back side or the end reflection heat insulating member 20, so that the diffusion sheet 12 is held. , Holding the light guide plate 11.

  A large number of LED elements 30 serving as light sources are arranged on the LED substrate 10 so as to be aligned roughly in the vertical direction (in FIG. 1). The outside of the LED element 30 is covered with an LED lens 31. The LED lens 31 is provided to efficiently extract the light emitted from the LED element 30 in the direction of the light guide plate. For example, the LED lens 31 is made of a transparent silicone resin having a high refractive index and high heat resistance. The

  The LED substrate 10 on which the LED element 30 is mounted is fixed to the LED light source block 9. In order to efficiently transmit the heat generated by the LED element to the LED light source block 9, it is desirable that a heat conductive grease or sheet is inserted and closely adhered between the LED substrate 10 and the LED light source block 9. Or it is still more suitable if it is soldered.

  The panel frame 8 is provided with a panel frame recess 8a that extends laterally at least from the LED light source block 9 to a position overlapping at least a part of the light guide plate / reflective sheet at the end, and further, in the panel frame recess 8a, An LED light source block 9 is fixed to the panel frame. In order to efficiently transfer heat from the LED light source block 9 to the panel frame 8, a heat conductive layer 23 is provided between the LED light source block and the panel frame. The heat conductive layer 23 is, for example, a heat conductive grease or sheet, and has a role of reducing the contact thermal resistance by absorbing the flatness variation of the fixed portion. Alternatively, the LED light source block and the panel frame may be soldered as the heat conductive layer 23.

  The LED light source block 9 needs to efficiently transmit the heat of the LED substrate 10 to the panel frame, and is preferably made of a material having high thermal conductivity, such as aluminum or copper. Further, it is desirable that the lateral thickness of the LED light source block 9 is at least thicker than the panel frame 8. Thereby, not only the thermal conductivity in the LED light source block can be further increased, but also the area of the thermal conductive layer 23 that is a contact portion with the panel frame can be increased, and the thermal resistance at the contact portion can be reduced.

  In addition, by bringing the end surface 9a of the LED light source block into contact with the panel frame 8, heat can be more efficiently transferred to the panel frame, but there is no particular limitation.

  The panel frame 8 is preferably made of a material having a high thermal conductivity in order to effectively diffuse the heat transmitted from the LED light source block 9 into the panel frame surface. Further, the panel frame 8 needs to have strength to hold a member such as a light guide plate. As a material that satisfies these requirements, the panel frame is made of aluminum, magnesium, or the like. Further, the panel frame 8 is bent toward the front side at the end portion, thereby increasing the strength and further diffusing the heat transmitted from the LED light source block to the panel frame at the end portion.

  The heat diffused by the panel frame 8 is transmitted to the rear exterior panel 4 or, if necessary, cooling air is introduced between the rear exterior panel 4 and the panel frame 8 so that the outside of the liquid crystal display device. Heat is dissipated.

  Furthermore, the edge reflection heat insulation member 20 is installed in the panel frame recessed part 8a in the area | region extended from the edge part of an LED light source block to at least one part of a light-guide plate and a reflective sheet. The end reflective heat insulating member 20 is configured so that the thickness thereof substantially matches the recess height of the panel frame recessed portion 8a, so that the end reflective heat insulating member has the light guide plate and the reflection sheet at the end. It can be held from the back side. In particular, since the reflection sheet is thin, the flat surface cannot be maintained unless it is held at the end portion, and reflection of light by the reflection sheet may be hindered at the end portion. Moreover, the edge part reflection heat insulation member 20 is provided with the function to reflect light in the front side, and is provided with the function to suppress heat conduction in the thickness direction.

  As the end reflective heat insulating member 20, a reflective surface is formed on the front surface side, and the back surface of the reflective surface is a heat insulating layer made of a material / member having a lower thermal conductivity than that of the panel frame 8. desirable. Thereby, light can be reflected on the front side where the light from the light source of the end reflection heat insulating member is directly incident, and heat transmitted from the panel frame side can be effectively insulated on the back side. The reflection surface is formed by vapor-depositing aluminum in a mirror shape or applying a white pigment as in the above-described reflection sheet. Further, if the heat insulating layer is formed of a resin such as PET or PC as in the case of the above-described reflective sheet, a heat insulating function can be obtained.

  When the heat insulating layer is formed of a foamed resin containing bubbles inside, the effective thermal conductivity is further lowered, and the heat insulating effect is increased, which is preferable. In addition, the heat insulating layer needs to have a function of suppressing heat conduction in the thickness direction, but it is not always necessary to suppress heat conduction in the surface direction, for example, heat conduction in the thickness direction from the surface direction. You may be comprised with the material provided with the heat conductivity anisotropy with a low rate. As such a material, for example, a resin composite material including a filler oriented in a plane direction can be given.

  Moreover, it is good also considering the edge part reflection heat insulation member as a laminated body of a reflection sheet and a heat insulation member. In this case, the end reflection heat insulating member can have the same reflection characteristics as the reflection sheet, and the end reflection heat insulation member can be manufactured at low cost by using the reflection sheet and the member in common. Moreover, since the member of a heat insulation layer can be selected independently of a reflection layer, the heat insulation layer with a more desirable heat insulation function can be formed.

  Further, the end reflection heat insulating member 20 is disposed at a position substantially in contact with the LED light source block 9, and the bottom surface side is fixed to the panel frame 8. As a fixing method, for example, a double-sided tape may be used.

  Further, the end reflection heat insulating member is fixed to the panel frame and is slidable with the reflection sheet and the light guide plate. That is, the end reflection heat insulating member is configured not to prevent movement within the surface by merely holding the reflection sheet / light guide plate from the back side.

  Further, it is desirable that the panel frame recess 8a of the panel frame 8 is formed with a slight gap 15 after accommodating the end reflective heat insulating member 20. Since the panel frame recess 8a is wide enough to form the gap 15, even after the LED substrate 10 on which the LED element 30 is mounted is fixed to the panel frame 8, it is easy to avoid the end reflection heat insulating member while avoiding them. 20 can be fixed to the panel frame and assembled.

  Further, since the LED light source block 9 is disposed in the panel frame recess 8a of the panel frame 8, the end reflective heat insulating member 20 can be disposed closer to the LED light source block than the LED lens and disposed at a position that is in general contact. It is possible. Considering the light incident efficiency to the end portion of the light guide plate 11, the LED element 30 and the LED lens 31 need to be substantially at the same position as the light guide plate in the direction perpendicular to the display surface. Therefore, if the LED light source block 9 is not disposed in the panel frame recess 8a, it is difficult to secure a gap between the LED lens 31, the LED substrate 10, and the panel frame 8, and the end reflective heat insulating member 20 Cannot be placed close to the LED light source block 9 and substantially in contact therewith.

  A predetermined gap 32 is provided between the end portions of the light guide plate 11 and the reflection sheet 13 and the LED lens 31. The gap 32 is for preventing the light guide plate and the reflection sheet from coming into contact with the LED lens due to an impact applied due to variations in manufacturing accuracy or external factors. In general, when the size of the member increases, it becomes difficult to ensure the absolute dimensional accuracy, and the amount of deformation caused by impact increases. Therefore, when the size of the liquid crystal display device increases, the size of the gap 32 also needs to be increased. .

  The second reason for providing the gap 32 is thermal expansion. That is, as described above, the panel frame is made of a metal such as aluminum in order to efficiently diffuse the heat from the light source into the panel frame. On the other hand, the light guide plate and the reflection sheet are made of resin such as acrylic, PET, or PC. The rate of expansion (linear expansion coefficient) depending on the temperatures of aluminum, acrylic, PET, and PC is approximately as shown in FIG. Although the linear expansion coefficient of resin varies depending on molding conditions, the linear expansion coefficient of acrylic, PET, PC, etc. is generally much larger than that of metal.

  Therefore, when the temperature of the member rises due to the operation of the liquid crystal display device, the member expands as a whole, but in particular, the resin member expands relatively greatly. When the liquid crystal display device is enlarged, this expansion cannot be ignored. For example, it is assumed that the width of the liquid crystal display device is 1.5 m and the temperature of the member is 40 ° C. higher than that at the time of assembly. The expansion of aluminum is about 1.4 mm, whereas the expansion of resin (assuming acrylic in FIG. 4) is 4.2 mm, and there is a difference of about 2.8 mm between the two. Even if the light guide plate / reflective sheet is accurately positioned at the center of the liquid crystal display device, there is a difference in expansion amount of about 1.4 mm between the left and right ends.

  On the other hand, the LED light source block 9 to which the LED light source is fixed is fixed to the panel frame in order to efficiently transmit heat to the panel frame, and the LED element 30 and the LED lens 31 follow the expansion of the panel frame. Displace. Therefore, when the liquid crystal display device operates and the temperature rises inside, the thermal expansion causes the gap 32 between the LED lens and the light guide plate / reflective sheet to be smaller than when assembled. Furthermore, if the liquid crystal display device repeatedly operates and stops, the light guide plate / reflective sheet and the panel frame repeatedly slide due to the difference in thermal expansion, which may gradually shift their positional relationship. is there.

  Accordingly, the gap 32 is necessary for the above first and second reasons, and needs to be increased as the liquid crystal display device becomes larger.

  As described above, according to the present embodiment, the panel frame recess 8a extending from the LED light source block to at least a part of the light guide plate / reflective sheet is provided at the end of the panel frame, and the LED light source block 9 is recessed in the panel frame. The edge reflection heat insulating member 20 is fixed to the portion 8a, and further extends to the panel frame recess portion 8a from the end portion of the LED light source block to at least a part of the light guide plate / reflective sheet, and is fixed to the panel frame. The heat generated by the LED element is effectively transmitted to the panel frame via the LED substrate and the LED light source block, and is diffused within the panel frame, thereby effectively cooling the LED element. Can do. At this time, particularly in the vicinity of the LED light source block fixed to the panel frame recess 8a of the panel frame becomes high temperature due to the heat transmitted from the LED light source block. Since it is thermally insulated by the partial reflection heat insulating member 20, it can suppress that the edge part temperature of a light-guide plate becomes high temperature, and can thereby suppress the thermal degradation of a light-guide plate edge part.

  In addition, as described above, especially when the liquid crystal display device is enlarged, the gap 32 between the light guide plate / reflective sheet and the LED lens becomes large, and it becomes difficult to bring the reflective sheet close to the LED lens. The reflective heat insulating member 20 enables light to be reflected without leaking to the back side even in the vicinity of the LED lens, so that light from the light source can be efficiently incident on the light guide plate. In particular, even when the temperature inside the liquid crystal display device rises and the relative positional relationship between the light guide plate / reflective sheet and the panel frame shifts at the end due to thermal expansion, the end reflective heat insulating member and the reflective sheet slide. By moving, a reflecting surface is always formed on the entire back side, and light can be reflected without leaking to the back side, so that light from the light source can be efficiently incident on the light guide plate. In addition, since the end reflection heat insulating member and the reflection sheet partially overlap each other, the positional relationship of the liquid crystal display device gradually changes as a result of sliding due to the difference in thermal expansion in the process of repeated operation and stoppage. Even if they are deviated, a reflection surface is always formed on the entire back side, and light can be reflected without leaking to the back side, so that light from the light source can be efficiently incident on the light guide plate.

  In particular, the end reflective heat insulating member is a member in which a reflective surface is formed on the surface facing the liquid crystal panel and a heat insulating layer is provided on the side fixed to the panel frame. Light can be reflected on the front side where light from the light source is directly incident, and heat transmitted from the panel frame side can be effectively insulated on the back side.

  Furthermore, if the heat insulating layer is formed of a foamed resin containing bubbles inside, the effective thermal conductivity is further lowered to increase the heat insulating effect, which is preferable.

  In particular, the edge reflection heat insulation member is a laminate of the reflection sheet and the heat insulation member, so that the edge reflection heat insulation member can not only have the same reflection characteristics as the reflection sheet, but also suppress uneven light due to the difference in reflection characteristics. can do. Further, by using the reflection sheet and the member in common, the end reflection heat insulating member can be manufactured at low cost. In addition, since the members of the heat insulating layer can be selected regardless of whether the reflective layer is formed, a heat insulating layer having more desirable heat insulating properties can be formed.

  As described above, in the present embodiment, the light emitted from the light source is efficiently incident on the light guide plate, and at the same time, the LED light source is effectively cooled in the large liquid crystal display device, and the optical characteristics due to heat are reduced. A liquid crystal display device having favorable optical characteristics that suppresses deterioration can be provided.

  In the present embodiment, the LED light source is arranged at the end in the horizontal direction, but it can also be arranged at the end in the vertical direction using the structure of the present invention. Since the liquid crystal display device is generally long in the horizontal direction, even if the same number of LED elements are arranged in order to obtain the same amount of light, the LED element mounting density is lowered when arranged at the end in the vertical direction. The temperature can be lowered. Alternatively, the LED light source can be cooled in a larger liquid crystal display device.

  It is also possible to apply the structure of the present invention by arranging LED light sources at both the vertical end and the horizontal end. In this case, since the mounting density of the LED elements is further reduced, the temperature of the LED light source can be further reduced. Alternatively, the LED light source can be cooled in a larger liquid crystal display device.

Next, a liquid crystal display device according to another embodiment will be described.
FIG. 5 is a schematic cross-sectional view of an end portion of a liquid crystal display device in another embodiment, and corresponds to FIG. 3 in the embodiment shown in FIGS. As in FIG. 3, the front exterior panel, the rear exterior panel, and the electric circuit board are not shown for easy understanding of the drawing.

  The present embodiment is the same as the embodiment shown in FIGS. 1 to 3 except for the LED light source block 9 and the end reflection heat insulating member 20. The end reflective heat insulating member 20 includes a reflection sheet 20b on the front surface side, and the back surface side is formed of a laminate of members 20a partially hollow. The member 20a is preferably made of a resin in order to improve the heat insulation. Such a member 20a can be easily manufactured by resin molding, for example. In addition, the LED light source block 9 has a substantially divergent shape in which a portion fixed to the panel frame 8 is extended in the direction of the light guide plate as compared with a portion to which the LED substrate is attached. The reflection sheet 20b is formed of the same member as the reflection sheet 13 disposed on the back surface of the light guide plate, so that the end reflection heat insulating member can have the same reflection characteristics as the reflection sheet. However, it is not particularly limited, and for example, a surface having a reflection function may be formed on the front side of the member 20a.

  By taking this embodiment, the following effects are obtained in addition to the embodiment shown in FIGS. First, by forming a hollow portion in at least a part of the end reflective heat insulating member fixed to the panel frame, high heat insulation can be obtained due to the low thermal conductivity of air in the hollow portion. It can further suppress that the edge part temperature of a light-guide plate becomes high temperature compared with embodiment shown in FIGS. 1-3, and, thereby, further suppresses thermal degradation of a light-guide plate edge part. Can do.

  Further, as shown in the first embodiment, even if the heat insulating layer is formed of a foamed resin, the effective thermal conductivity can be reduced depending on the shape of the member as in this embodiment. When the part is formed, not only higher heat insulation can be obtained, but unlike foamed resin, a member with high shape dimensional accuracy can be created by resin molding, and the rigidity of the member is compared with foamed resin. Can be expensive. As a result, the light guide plate and the reflection sheet can be more reliably held at the end.

  Furthermore, as shown in FIG. 5, at the position where the LED light source block and the end reflection heat insulating member 20 are in general contact, the member 20 a is fixed to the panel frame 8 of the LED light source block 9 by making the back side hollow. The portion can be extended toward the light guide plate 11. Thereby, the area of the fixing part of the panel frame and the LED light source block 9 can be increased, the thermal resistance between the LED light source block 9 and the panel frame 8 is reduced, and the heat from the LED light source is effectively reduced to the panel frame. Can diffuse.

  Next, a liquid crystal display device according to still another embodiment will be described. FIG. 6 is a schematic cross-sectional view in the present embodiment, and corresponds to the portion of FIG. 2 in the embodiment shown in FIGS.

  This embodiment is substantially the same as the embodiment shown in FIGS. 1 to 3 except that the shape of the back exterior panel 4 is different. The electric circuit boards 5, 6, and 7 are arranged at a substantially central portion on the inner side (display area central side) of the panel frame recess 8 a, and the rear exterior panel 4 has the electric circuit boards 5, 6, and 7 at the substantially central portion. While being accommodated, the end portion where the LED light source block 9 is disposed is opposed to the panel frame 8 and is pushed out to the front side to a substantially close position. Further, the rear exterior panel 4 has a rear exterior panel recess 4a. The rear exterior panel recess 4a is provided on the side facing the panel frame 8 in the vicinity where the LED light source block is fixed. The rear exterior panel recess 4a does not need to be one at each end, and may be configured with a plurality of recesses in consideration of the strength, formability, and the like of the rear exterior panel 4.

  As described in the embodiment of FIGS. 1 to 3, the heat of the light source transmitted to the panel frame 8 is diffused in the panel surface, then transmitted to the back exterior panel, and radiated to the outside air. Alternatively, heat is radiated to the outside of the liquid crystal display device by allowing cooling air to enter between the rear exterior panel 4 and the panel frame 8 as necessary. In the present embodiment, the back exterior panel 4 faces the panel frame 8 at the end and is pushed to the front side to a position that is substantially close to the end, so that the end is between the back exterior panel 4 and the panel frame 8. Although the cooling air cannot be introduced, if necessary, the cooling air may be introduced into a substantially central portion in which the electric circuit boards 5, 6, and 7 are accommodated.

By taking this embodiment, the following effects can be obtained in addition to the embodiment shown in FIGS.
First, the electric circuit boards 5, 6, 7 are arranged inside the panel frame recess 8 a in the substantially central part (display area central side), and the rear exterior panel 4 is arranged in the approximate center of the electric circuit boards 5, 6, 7. While being accommodated in the portion, the liquid crystal display device can be made thinner at the end portion by pushing it to the front side to a position that faces the panel frame 8 at the end portion and is approximately close to the panel frame 8. Further, by disposing the electric circuit boards 5, 6 and 7 inside the panel frame recess 8a (display area center side), the electric circuit board and the panel frame recess 8a do not overlap each other. Also, the thickness of the liquid crystal display device can be suppressed. Furthermore, since the rear exterior panel 4 is pushed to the front side to a position where the rear exterior panel 4 is substantially close to the panel frame 8, the gap between the panel frame recess 8 a and the rear exterior panel is reduced, and heat is transferred. As a result, the heat transmitted from the LED element to the LED light source block and the panel frame can be efficiently radiated from the back surface.

  Furthermore, the LED light source block is fixed by providing the rear exterior panel recess 4a on the side facing the panel frame 8 in the vicinity where the LED light source block of the rear exterior panel 4 is fixed. In the vicinity, the rear exterior panel can be prevented from locally becoming high temperature. In the panel frame 8, the vicinity where the LED light source block is fixed is the highest temperature because the high temperature of the LED light source block is directly transmitted. For this reason, if there is no rear exterior panel recess 4a, the rear exterior panel and the panel frame 8 are close to each other at the end, so that the high temperature is transmitted to the rear exterior panel, and the rear exterior panel is locally It becomes high temperature. A high temperature is desirable from the viewpoint of heat dissipation from the rear exterior panel to the outside air, but if the temperature is too high, it will cause problems such as burns when touched by people, so the temperature of the rear exterior panel should be kept below a certain level. is necessary.

  By forming the back exterior panel recess 4a, it is possible to prevent heat from being transmitted from the panel frame 8 to the back exterior panel in the vicinity where the LED light source block is fixed. It can suppress becoming high temperature. Further, the temperature of the panel frame 8 is the highest in the vicinity where the LED light source block is fixed, but the temperature gradually decreases as the distance from the vicinity increases because the heat spreads in the panel frame surface. Therefore, by providing the rear exterior panel recess 4a, the rear exterior panel is prevented from becoming high in the rear exterior panel recess 4a, and at the other temperatures, the rear exterior panel and the panel frame 8 are reduced. The temperature distribution of the rear exterior panel can be made uniform by actively transferring heat to the rear exterior panel. As a result, it is possible to increase the overall temperature while suppressing the local high temperature of the back exterior panel, and heat can be effectively released from the back exterior panel to the outside air.

  Further, since the rear exterior panel recess 4a is formed inside the liquid crystal display device, it can effectively radiate heat without affecting the appearance of the back surface of the liquid crystal display device, and a liquid crystal display having a desirable appearance. An apparatus can be provided.

  As described above, in the present embodiment, it is possible to efficiently dissipate heat to the outside air from the rear exterior panel while realizing thinning of the liquid crystal display device. As a result, the temperature of the LED element and the end of the light guide plate can be reduced. It is possible to provide a liquid crystal display device that can be lowered, is thin, and has good optical characteristics.

  As described above, according to the present invention, the panel frame is provided with a recessed portion extending to at least a part of the light guide plate / reflective sheet, and the light guide plate / reflector is further provided in the recessed portion from the end of the LED light source block. By providing an end reflective heat insulating member that extends to at least a part of the sheet and is fixed to the panel frame, even in a large liquid crystal display device, when light emitted from a light source is efficiently incident on a light guide plate At the same time, it is possible to provide a liquid crystal display device having good optical characteristics that effectively cools the LED light source and suppresses deterioration of the optical characteristics of the light guide plate due to heat.

1 is a schematic configuration diagram of a liquid crystal display device according to an embodiment of the present invention. The AA 'cross-sectional schematic diagram in FIG. The cross-sectional schematic diagram which expanded the edge part of FIG. The table | surface which shows the linear expansion coefficient in various materials. The cross-sectional schematic diagram which concerns on one embodiment by this invention. The cross-sectional schematic diagram which concerns on one embodiment by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Front exterior panel 3 Liquid crystal panel 4 Rear exterior panels 5, 6, 7 Electric circuit board 8 Panel frame 8a Panel frame recessed part 9 LED light source block 9a End surface 10 of LED light source block LED board 11 Light guide plate 12 Diffusion sheet 13 Reflection sheet 14 Panel gaps 15 and 32 Gap 20 End reflection heat insulating member 23 Thermal conduction layer 25 Front frame 26 Light guide plate pressing member 30 LED element 31 LED lens 39 Panel pressing rubber

Claims (5)

A liquid crystal panel, an LED light source provided at at least one end of the display surface, an LED light source block equipped with the LED light source, and light from the LED light source provided on the back side of the liquid crystal panel In a liquid crystal display device comprising: a light guide plate that leads to the light guide plate; a reflection sheet provided on the back side of the light guide plate; a panel frame that fixes the LED light source block and holds the light guide plate and the reflection sheet from the back side;
At the end of the panel frame where the LED light source block is disposed, a recess is provided that extends at least from the LED light source block to at least a part of the light guide plate / reflective sheet, and the end of the LED light source block is further provided in the recess. A liquid crystal display device comprising an end reflection heat insulating member that extends from a portion to at least a part of the light guide plate / reflective sheet and is fixed to the panel frame. The liquid crystal display device according to claim 1.
The liquid crystal display device, wherein the end reflective heat insulating member has a reflective surface formed on a surface facing the liquid crystal panel and a heat insulating layer provided on a side fixed to the panel frame. The liquid crystal display device according to claim 1.
The liquid crystal display device, wherein the end reflective heat insulating member is formed of a laminate of the reflective sheet and the heat insulating member. The liquid crystal display device according to claim 1.
The end reflective heat insulating member has a reflective surface formed on a surface facing the liquid crystal panel, and a hollow portion is formed on at least a part of the side fixed to the panel frame. apparatus. The liquid crystal display device according to claim 1.
The liquid crystal display device, wherein the end reflection heat insulating member is in contact with the light guide plate and the reflection sheet in a slidable form.

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