JP2005283852A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device having an LED back light which can suppress decrease in the light emission efficiency of a light emitting diode chip and realizes bright long-life liquid crystal display. <P>SOLUTION: The display comprises a liquid crystal display element 1 and the LED back light 2 comprising an LED mounting substrate 22 mounting a light guide plate 21 and an LED chip 23. On the LED chip mount surface of the LED mounting substrate 22, a mounting metal film 25 where the LED chip is to be mounted, metal driving wire 26 to supply a driving current to the LED chip, and a metal film pattern 27 formed to surround the metal driving wiring 26 are formed, while a heat radiation metal film 28 is formed on the surface facing the LED mount surface, with the metal film pattern 27 and the heat radiation metal film 28 joined by a metal through hole which connects them. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  2. Description of the Related Art Conventionally, among transmissive and transflective liquid crystal display devices among liquid crystal display device display methods, a liquid crystal display element and a backlight for supplying a light source that transmits the liquid crystal display element are arranged.

  In general, a backlight includes a light source and a light guide plate, and a small fluorescent tube called a CFL (cold cathode tube) is used as the light source. Further, the light guide plate faces the liquid crystal display element side main surface (front surface) so as to face the display area of the liquid crystal display element, and the main surface (back surface) opposite to the main surface transmits light to the surface side. A diffusion part that diffuses and reflects is formed. The light source, which is a cold cathode tube, is disposed on the end face of the light guide plate, and the light of the cold cathode tube incident from the end face of the light guide plate is transmitted into the light guide plate and diffused / reflected on the back side. The light is emitted from the surface side of the light guide plate and supplied to the display area of the liquid crystal display element. That is, the cold cathode tube is disposed on the end face of the light guide plate, and the white light of the cold cathode tube incident on the end face is uniformly diffused in the light guide plate surface by the diffusion portion provided on the back surface of the light guide plate. , Converted from a linear light source to a planar light source.

  However, in this CFL light source, Hg (mercury) is enclosed in a discharge tube, and ultraviolet rays emitted from mercury excited by discharge strike the phosphor on the CFL tube wall and convert it into visible light. For this reason, in consideration of the environment, the use of an alternative light source is required by suppressing the use of harmful mercury.

  On the other hand, a backlight using a light emitting diode (LED) having a feature of a point light source as a light source has been developed as a new light source. A backlight using this LED as a light source (LED backlight) is becoming widespread as a backlight of a liquid crystal display element with a reduction in price, improvement in luminous efficiency, and environmental regulations. At the same time, with the increase in brightness and size of liquid crystal display devices (increase in display area), there is an increasing demand for a plurality of LED light sources.

  Therefore, in order to obtain an LED backlight for use with a high-luminance and large-sized liquid crystal display element, a point light source is converted into a planar light source (uniform light on the surface of the light guide plate) by converting the LED light source. For example, it is necessary to control the material and structure of the diffusion portion on the back surface of the light guide plate and to arrange the LED light source at an optimum position according to the directivity of the LED light source.

  The biggest problem is the luminous efficiency of the LED light source. Although the luminous efficiency of LEDs has been improved by recent improvements, the luminous efficiency is about 10% at present, and the remaining 90% is released as heat. That is, even in a backlight using an LED as a light source, this generated heat is stored on the substrate on which the LED is mounted, and the luminous efficiency of the LED itself is reduced as the temperature of the substrate increases. Furthermore, this heat causes damage to the LED and the wiring of the LED mounting substrate. In addition, if the number of mounted LEDs is increased to increase the brightness of the backlight, the amount of heat generated increases, so this heat generation cannot be ignored further.

The structure of a white LED is known on one side of a flexible substrate, which is a substrate for a linear light source having a power supply terminal as disclosed in Japanese Patent Laid-Open No. 2001-75038, for example, but heat generated from the LED light source No proposal has been made to radiate heat, prevent the luminous efficiency of the LED light source from decreasing, and further prevent damage to the LED light source.
JP 2001-75038 A

  However, the LED backlight used in the liquid crystal display device and disposed on the back side of the liquid crystal display element is provided with a metal wiring such as copper on one side of a flexible substrate made of polyimide or polyester or an insulating substrate made of glass epoxy, The LED light source is mounted on the wiring, and the back surface of the insulating substrate (the back surface of the surface on which the LED light source is mounted) is placed in surface contact with the casing or the heat sink of the liquid crystal display device. The heat conductivity of the insulating substrate is extremely small compared to a metal material or the like, and heat generated from the light source of the LED is stored on the insulating substrate. As the temperature of the LED increases, the luminous efficiency of the LED decreases. The problem of damage would occur.

  The present invention has been devised in view of the above-described problems, and its object is to improve the heat conduction of an LED mounting substrate on which an LED light source is mounted in a liquid crystal display device having an LED backlight. The heat generated by the LED light source is efficiently dissipated to the back side of the substrate, and further to the outside, the heat storage of the LED mounting substrate is reduced, and the temperature rise of the LED is reduced, thereby reducing the luminous efficiency of the LED. In addition, it is possible to provide a liquid crystal display device having an LED backlight capable of suppressing the damage of the LED and preventing the LED from being damaged and performing a bright and long-life liquid crystal display.

The liquid crystal display device of the present invention comprises at least a display electrode and a pair of transparent substrates having an alignment film, a liquid crystal display element having a liquid crystal layer interposed so that the display electrodes face each other,
A backlight comprising a light guide plate and a light emitting diode mounting substrate on which a light emitting diode chip to be supplied to the light guide plate is mounted, facing the other transparent substrate of the liquid crystal display element; In the liquid crystal display device, a light-emitting diode mounting surface of the light-emitting diode mounting substrate includes a mounting metal film on which the light-emitting diode chip is mounted, a metal driving wiring for supplying a driving current to the light-emitting diode chip, and the metal driving wiring. A metal film pattern formed so as to surround is formed, and a metal film for heat dissipation is formed on a surface facing the light emitting diode chip mounting surface, and the metal film pattern is formed in the thickness direction of the light emitting diode mounting substrate. And a metal through-hole connecting the heat-dissipating metal film.

  The mounting metal film is connected to the heat radiating metal film through a metal through hole formed in the direction of the thickness of the light emitting diode mounting substrate.

  The light emitting diode mounting substrate is disposed on an end face of the light guide plate, and an outer main surface of the light guide plate surface of the light emitting diode mounting substrate and a surface facing the light emitting diode chip mounting surface of the light emitting diode mounting substrate are provided. A substantially identical surface is formed, and a reflective metal plate is disposed on the same surface.

  Further, each metal film, wiring, and metal through hole of the light emitting diode mounting substrate is formed of copper or a copper-based metal material.

  Further, the liquid crystal display element and the backlight are accommodated in a casing made of Al (aluminum), Mg (magnesium), Fe (iron), or an alloy of these metals, and the casing is directly or indirectly It is characterized by being bonded to a metal film for heat dissipation.

  In the liquid crystal display device of the present invention, a mounting metal film on which the LED chip is mounted on the LED chip mounting surface (one main surface side) of the light emitting diode (LED) mounting substrate, and metal driving for supplying a driving current to the LED chip. A wiring and a metal film pattern for heat dissipation are formed, a metal film for heat dissipation is formed on the surface facing the LED chip mounting surface (the other main surface side), and one main surface in the thickness direction of the LED mounting substrate A metal through hole that connects the metal film pattern on the side and the metal film for heat dissipation on the other main surface side is formed. Therefore, the heat converted by the LED chip is transferred from the metal film pattern on the one main surface side to the heat radiating metal film on the other main surface side through the metal through hole, and the heat generated by the LED chip is dissipated. Is efficiently conducted to the metal film for heat dissipation.

  This reduces the heat storage of the LED mounting substrate and reduces the temperature rise of the LED chip, thereby suppressing the light emission efficiency of the LED chip, preventing damage to the LED, and enabling a bright long-life LCD display A liquid crystal display device having a light can be provided.

  Moreover, the LED chip as the heat source is mounted with a mounting metal film, and the mounting metal film is bonded to the heat radiation metal film on the other main surface side through a metal through hole. For this reason, the heat generated from the LED chip can be transmitted to the metal film for heat dissipation at the shortest distance. However, the shape of this LED chip is very small, the area of the mounting metal film is limited, and the number of metal through holes that can be formed immediately below is also limited. For this reason, the mounting metal film is integrally formed by joining the metal film pattern, and the heat of the mounting metal film is efficiently transferred to the metal film pattern, so that there is no restriction on the formation of the metal through hole. It may be transmitted to the metal film for heat dissipation formed on the back surface side of the LED mounting substrate.

  In addition, the LED mounting substrate is arranged in parallel with the end surface of the light guide plate, and the outer main surface of the light guide plate surface and the surface (back surface) facing the LED chip mounting surface of the LED mounting substrate are substantially the same surface. Then, a reflective metal plate that is common to the light guide plate and the LED mounting substrate is disposed on the same surface. For this reason, the reflective metal plate can be easily brought into surface contact with the heat dissipating metal film on the back surface side of the LED mounting substrate, whereby the heat dissipating substrate film is efficiently passed through the very large area reflective metal plate. It can dissipate heat to the outside.

  In addition, since each metal film, wiring, and metal through hole of the light emitting diode mounting substrate are made of copper or a copper-based metal material, the thermal conductivity is better than that of the mounting substrate, so it is very efficient. Heat can be dissipated.

  Further, the heat-dissipating metal thin film on the other main surface side of the reflective metal plate or the mounting substrate is Al (aluminum), Mg (magnesium), Fe (iron), or an alloy of these metals that accommodates the liquid crystal display element and the backlight Accordingly, heat can be stably dissipated to the outside of the liquid crystal display device.

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

  FIG. 1 is a schematic sectional view of a liquid crystal display device of the present invention. 2 to 4 are schematic views of an LED mounting substrate of an LED backlight used in the liquid crystal display device of the present invention, and FIG. 5 is an enlarged view of a main part of the backlight.

  The liquid crystal display device of the present invention is mainly composed of a liquid crystal display element 1, an LED backlight 2, and a housing 3 that accommodates both.

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

  The display electrode constituting the internal structure of the lower transparent substrate 11 and the display electrode constituting the internal structure of the upper transparent substrate 12 form a display pixel region arranged in a matrix form facing each other.

  For example, in a transmissive liquid crystal display device, one pixel constituting each display pixel region serves as a light transmissive portion in which the display electrodes are all transparent electrodes and can transmit the light of the backlight 2. In the liquid crystal display device, a light reflecting portion, part of which is made of a reflective metal film, and a light transmitting portion, which is partly capable of transmitting the light of the backlight 2, are provided side by side. In other words, in this transflective liquid crystal display device, external light incident from the display surface side is used to be reflected by the light reflecting portion in the pixel region and returned to the display surface side, and also to transmit the light from the backlight 2. The light is given to the display surface side. Thus, when the external light is strong, the display is performed in the reflective mode, and when the external light is weak, the display is performed in the transmissive mode.

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

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

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

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

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

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

  In this way, the liquid crystal display element 1 is configured. The LED backlight 2 is disposed on the outside of the lower substrate 11 which is the other transparent substrate of the liquid crystal display element 1. Specifically, the LED backlight 2 includes a light guide plate 21 and a light emitting diode mounting substrate 22 on which a light emitting diode chip 23 supplied to the light guide plate 21 is mounted. The surface (surface from which light is emitted) is disposed so as to face the display region of the liquid crystal display element 1.

  The light guide plate 21 constituting the LED backlight 2 is made of a transparent resin substrate, and a light scattering member may be contained in the resin component. On the other main surface of the light guide plate 21, a reflection portion for diffusing and reflecting light is formed. This reflective part is intended to radiate light propagating in the substrate to one main surface side. A groove for diffusing and reflecting directly on the other main surface is formed, and further diffused to the other main surface. -You may form the coating film which has a reflective function, and also affix a reflective metal substrate on the other main surface.

  In the figure, an example using a reflective metal plate 24 is shown. Note that a scattering layer may be formed on the surface of the reflective metal plate 24 for the purpose of light scattering, or fine scattering grooves may be formed. Further, a fine scattering groove may be formed on the other main surface side of the light guide plate 21.

  A light emitting diode mounting substrate 22 is disposed on the end face portion of the light guide plate 21 so as to be juxtaposed with the light guide plate 21. In FIG. 1, for example, the light emitting diode chip 23 of the light emitting diode mounting substrate 22 is disposed so as to face the end face of the light guide plate 21. The back surface of the LED mounting substrate 22 is directly bonded to the inner surface of the side surface of the metal housing 30 of the liquid crystal display device.

  Further, the mounting surface on which the light emitting diode chip 23 of the light emitting diode mounting substrate 22 is mounted is arranged so as to be orthogonal to the end surface of the light guide plate 1. This may be selected in consideration of the light directivity of the light-emitting diode chip 23, and may be arranged so that light from the light-emitting diode chip 23 can be supplied to the maximum from the end face of the light guide plate 21.

  Further, the light emitting diode mounting substrate 22 is made of a glass cloth base epoxy resin substrate or a ceramic substrate. On the LED mounting surface, a mounting metal film 25 for mounting the LED chip 23 and metal driving for supplying a predetermined driving current to the LED chip. A metal film pattern 27 is formed so as to surround the wiring 26 and the metal drive wiring 26. Further, a heat radiating metal film 28 is formed over substantially the entire surface on the surface opposite to the mounting surface and on the back surface side.

  Further, a plurality of metal through holes 29 for connecting the metal film pattern 27 and the heat radiating metal film 28 are formed in the thickness direction of the LED mounting substrate 22.

  The mounting metal film 25 is also connected to the heat radiating metal film 27 through a metal through hole 29 formed in the direction of the thickness of the LED mounting substrate 22.

  Each of the metal films 25, 27, 28, the wiring 26, and the metal through hole 29 is formed of, for example, copper or a copper-based metal material (a copper alloy or copper whose surface is covered with copper oxide).

  Note that the predetermined drive current supplied to the light emitting diode 23 constitutes an input terminal by the metal drive wiring 26 extending to the end of the mounting substrate 22.

  The LED chip 23 is bonded and fixed to, for example, a mounting metal film 25, and the electrodes of the LED chip 23 are connected to the metal drive wiring 26 via a conductive member, and are mounted on the mounting substrate 22 at a predetermined interval. It will be. Here, when the LED chip 23 is bonded to the mounting metal film 25, an insulating adhesive is used. This is to prevent unnecessary short circuit with the LED chip 23. If the portion of the LED chip 23 that is connected to the mounting metal film 25 is at a ground potential, the mounting metal film 25, the metal through hole 29, the heat dissipation metal film 28, and the metal film pattern 27 are all set to the ground potential. This is very important.

  The relationship between the LED mounting substrate 22 and the light guide plate 21 is such that the back surface of the LED mounting substrate 22 is directly bonded to the metal housing 30 and the LED chip 23 is connected to the end surface of the light guide plate 21 as shown in FIG. There is a structure to face. As another structure, as shown in FIG. 5 (a), the back surface of the LED mounting substrate 22 and the other main surface of the light guide plate 21 are flush with the other main surface of the light guide plate 21, for example. There is a structure in which the LED plate 22 is mounted on the reflective metal plate 24 by extending the metal plate 24. That is, it is important that the light emitted from the LED chip 23 is supplied to the end face of the light guide plate 21 by setting the thickness of the LED mounting substrate 22 to be thinner than the thickness of the light guide plate 21. At this time, the reflective metal plate 24 and the heat dissipating metal film 28 on the back surface side of the LED mounting substrate 22 are in surface contact. In the case of this structure, a chip with a wide light emission directivity of the LED chip 23 is desirable.

  Further, as shown in FIG. 5B, the end surface of the light guide plate 21 and the mounting surface of the LED mounting substrate 22 are arranged so as to face each other, and the reflective metal plate 24 is extended so that the tip portion thereof is L. There is a structure that is bent in a letter shape and fixed so that the back surface of the LED mounting substrate 22 is in surface contact with a part of the bent reflective metal plate 24.

  In any case, the heat dissipation metal film 28 formed on the back surface of the LED mounting substrate 22 is a metal member other than the mounting substrate 22, for example, the reflective metal plate 24 attached to the light guide plate 21 or the entire device. It is important that the metal housing 30 is fixed in direct surface contact or indirectly through an adhesive material.

  Thereby, in order to improve the visibility of the display information of the liquid crystal display element 1, when the backlight 2 of the liquid crystal display device is driven (the LED chip 23 is driven to turn on), heat is generated along with the light emission. The generated heat is generated on the mounting surface side of the LED mounting substrate 22, but the heat dissipating metal on the back surface side from the mounting metal film 25 or the metal film pattern 27 on the mounting surface side through the metal through hole 29. It is transmitted to the film 28.

  Therefore, since the heat generated in the LED chip 23 is not easily stored in the substrate 22, the temperature rise of the LED chip 23 can be effectively suppressed.

  Moreover, the heat dissipation metal film 28 is directly or indirectly applied to a member different from the LED mounting substrate 22, for example, the reflective metal plate 24 or the metal housing 30 of the liquid crystal display device. Since these are in surface contact, the reflective metal plate 24 and the metal casing 30 of the liquid crystal display device act as a heat sink, and the heat accumulated in the LED mounting substrate 22 is effectively radiated to the outside. The temperature rise of the LED chip 23 can be suppressed very effectively.

  These functions are such that the display area of the liquid crystal display element 1 is enlarged, the shape of the light guide plate 21 is enlarged, and a large number of LEDs are supplied to the LED mounting substrate 22 in order to supply sufficient light to the enlarged light guide plate 21. The more chips 23 are formed, the greater the effect.

  The metal through-hole 29 is very important as a means for transmitting heat generated by the LED chip 23 to the back side of the LED mounting substrate 22. The larger the number of metal through holes, the more effectively it works. In addition, it is very effective to provide the metal through hole 29 in the mounting metal film 25 especially for heat dissipation. However, since the mounting metal film 25 formed for mounting purposes is required to have a flat surface, it is desirable that the metal through hole 29 be formed so as not to affect the surface shape.

  Practically, the mounting metal film 25 and the metal film pattern 27 are integrally formed, and a plurality of metal through holes 29 are provided so as to avoid the area where the LED chip 23 is actually mounted and to be close to this area. It is important to provide

  The metal housing 30 acting as a heat sink of the LED mounting substrate 22 has a thickness of 2 mm, and the material is aluminum, and is fixed by screws so as to be in surface contact with the heat dissipating metal film 28 of the LED mounting substrate 22.

  Here, the thermal conductivity of each material used is 0.45 W / m · K for the LED mounting substrate 22 made of glass epoxy, 403 W / m · K for the metal film, Cu that is a wiring or metal through hole, and the metal housing. Some aluminum is 236 W / m · K.

  Heat generated along with light emission in the LED chip 23 passes through the mounting metal film 25 provided immediately below the LED chip 23 and is diffused to the entire surface of the metal wiring pattern 27 provided on the entire surface of Cu having extremely high thermal conductivity. In addition, the heat is transmitted to the heat radiating metal film 28 formed on the back surface side of the LED mounting substrate 22 through the plurality of metal through holes 29.

  The heat radiating metal film 28 is thermally conducted to the metal housing 30 made of aluminum and radiated.

  Here, the thermal conductivity of the LED mounting substrate 22 is very small compared to a metal film, a metal wiring pattern, and a metal through hole, and compared to a metal material used for the metal housing 30 that acts as a heat sink, In order to improve heat conduction, a method of reducing the thickness of the mounting substrate 22 as much as possible is effective. Further, the metal housing 30 may be aluminum, magnesium, or iron. Incidentally, the thermal conductivity of magnesium is 157 W / m · K, and the thermal conductivity of iron is 83.5 W / m · K. If the heat dissipation is poor, increase the plate thickness or What is necessary is just to provide a heat radiation fin except a surface contact part.

  Then, using the 5.7 inch size liquid crystal display element 1 as the size of the display area, five LED chips 23 are arrayed and mounted on the LED mounting substrate 22, and a current of 250 mA is applied to each LED chip. The temperature rise on the mounting surface was measured. As a result, the mounting surface side can be suppressed to 25 ° C. or lower, and the temperature increase on the back surface side of the mounting substrate 22 can be suppressed to 18 ° C. or lower, and the luminous efficiency can be reduced by about 2% compared to the room temperature luminous efficiency of the LED light source. And bright display is possible.

On the other hand, if the metal wiring pattern is formed only on the mounting surface side of the LED mounting board, the temperature rise of the LED mounting board is large, the temperature rise of the LED mounting board is 50 ° C. or more, and the luminous efficiency of the LED light source is 4 %, And the usage environment of the liquid crystal display device is 70 ° C. compared to normal temperature (25 ° C.), the temperature of the LED mounting substrate is 120 ° C. or higher, and the LED light emitting element is expected to be damaged. .

From the above experimental confirmation results, the heat conduction of the LED mounting board 22 is reduced by improving the heat conduction of the LED mounting board and efficiently transferring the heat generated by the LED chip 23 to the heat sink. By reducing the temperature rise, it is possible to suppress a decrease in light emission efficiency of the LED chip and prevent damage to the junction at the connection part of the LED chip or the LED chip, thereby realizing a bright and long-life liquid crystal display device.

It is a schematic sectional drawing of the liquid crystal display device of this invention. It is sectional drawing of the LED mounting board | substrate of the LED backlight used for the liquid crystal display device of this invention. It is a schematic perspective view by the side of the mounting surface of the LED mounting board of the LED backlight used for the liquid crystal display device of this invention. It is a schematic perspective view of the back surface side of the LED mounting board of the LED backlight used for the liquid crystal display device of this invention. (A) shows the fixing structure of a mounting board, (b) shows the fixing structure of another mounting board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display element 2 ... Backlight 21 ... Light guide plate 22 ... Light emitting diode (LED) mounting board 23 ... Light emitting diode (LED) chip 24 ... ..Reflective metal plate 25 ... Mounting metal film 26 ... Metal drive wiring 27 ... Metal film pattern 28 ... Metal film for heat dissipation 29 ... Metal through hole 30 ...・ Metal housing

Claims (5)

A pair of transparent substrates having at least a display electrode and an alignment film, a liquid crystal display element having a liquid crystal layer interposed so that the display electrodes face each other;
A backlight comprising a light guide plate and a light emitting diode mounting substrate on which a light emitting diode chip to be supplied to the light guide plate is mounted, facing the other transparent substrate of the liquid crystal display element; In the liquid crystal display device
The light emitting diode mounting surface of the light emitting diode mounting substrate is formed so as to surround the mounting metal film on which the light emitting diode chip is mounted, the metal driving wiring for supplying a driving current to the light emitting diode chip, and the metal driving wiring. A metal film pattern is formed, and a heat radiating metal film is formed on a surface facing the light emitting diode chip mounting surface, and the metal film pattern and the heat radiating metal film are formed in the thickness direction of the light emitting diode mounting substrate. A liquid crystal display device characterized in that a metal through hole is formed to connect the two.   2. The liquid crystal display device according to claim 1, wherein the mounting metal film is connected to the heat radiating metal film through a metal through hole formed in the direction of the thickness of the light emitting diode mounting substrate.   The light emitting diode mounting substrate is disposed on an end surface of the light guide plate, and an outer main surface of the light guide plate surface of the light emitting diode mounting substrate is substantially flush with a surface facing the light emitting diode mounting surface of the light emitting diode mounting substrate. The liquid crystal display device according to claim 1, wherein a reflective metal plate is disposed on the same surface.   The liquid crystal display device according to claim 1, wherein each metal film, wiring, and metal through hole of the light emitting diode mounting substrate is made of copper or a copper-based metal material.   The liquid crystal display element and the backlight are accommodated in a casing made of Al (aluminum), Mg (magnesium), Fe (iron), or an alloy of these metals, and the casing directly or indirectly radiates heat. 4. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is bonded to a metal film for use.

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