JP2005195623A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively radiate heat generated from a liquid crystal display unit, regarding a liquid crystal display. <P>SOLUTION: The liquid crystal display is provided with a liquid crystal panel, an illuminator for illuminating the liquid crystal panel and a plate-shaped member 26 disposed in the vicinity of the illuminator. The plate-shaped member has a metal base material and a surface part 26A, at least partially covering the metal base material and having emissivity which is higher than that of the metal base material. An outer case has air vents at positions in the vicinity of the liquid crystal display unit. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device.

  The liquid crystal display device includes a liquid crystal display unit housed in a plastic outer case. The liquid crystal display unit is attached to the base plate, and the base plate is fixed to the outer case. Circuit components are attached to the base plate.

  The liquid crystal display unit includes a liquid crystal panel, a lighting device, a rear case that houses the lighting device, and a front cover that partially covers the front surface of the liquid crystal panel. The liquid crystal panel and the lighting device form a liquid crystal display unit with the rear case and the front cover attached. Further, the liquid crystal display device includes an outer case that accommodates these members.

  Illumination devices include sidelight type backlights and direct type backlights. In the sidelight type backlight, a light guide plate is disposed behind the liquid crystal panel, and a light source such as a cold cathode tube is disposed on a side portion of the light guide plate. The light source and the light guide plate are housed in the rear case. On the other hand, in the direct type backlight, a plurality of light sources such as cold cathode fluorescent lamps are arranged behind the liquid crystal panel, and these light sources are housed in a rear case.

  The rear case for housing the lighting device and the front cover disposed on the front surface of the liquid crystal unit are formed by processing a metal plate into a sheet metal. As the metal plate for making the rear case and the front cover, an aluminum plate material having high thermal conductivity and high mechanical strength, for example, 5052 series aluminum is used. The liquid crystal display unit is fixed to the base plate and disposed in the outer case. The base plate is made of galvanized steel plate. Various circuit components are mounted on the rear side of the base plate.

  In this way, the liquid crystal display device can be used as a television or a monitor. In recent liquid crystal display devices, the size is increasing and the brightness is increasing. At the same time, there is a problem that the power consumption of the liquid crystal display device increases, the temperature inside the outer case rises, and the performance of various members and the liquid crystal panel deteriorates. In particular, the light source and the circuit member are heat sources. When the temperature of these members rises, the performance of the member itself deteriorates, and problems such as a decrease in the transmittance of the liquid crystal occur. Furthermore, the cold cathode tube used as the light source has a problem that the luminous efficiency decreases when the temperature rises excessively.

  Therefore, it is necessary to suppress an increase in the temperature inside the liquid crystal display device. For this reason, an air hole is provided at a position behind the base plate of the outer case of the liquid crystal display device so that heat generated from the circuit member attached to the base plate is discharged to the outside of the liquid crystal display device. However, the heat generated from the liquid crystal display unit is not easily discharged from the plate-like members (rear case and front cover) constituting the outer surface of the liquid crystal display unit.

  There is an example in which a hole or an opening is provided in the rear case in order to discharge heat generated in the liquid crystal display unit from the rear case (plate-like member) (see Patent Documents 1, 2, and 3). In addition, there is an example in which unevenness is formed on the rear case so as to contact the support member of the light source (see Patent Document 4).

JP-A-6-347784 Japanese Patent Laid-Open No. 7-49497 Japanese Patent Laid-Open No. 11-126028 JP 2001-216807 A

  The rear case of a liquid crystal display unit is often made of a 5052 series aluminum plate that has high thermal conductivity, can maintain a predetermined strength even if it is thin and light, and has good workability. However, although the aluminum plate has good thermal conductivity, it is difficult to exhaust heat from the aluminum plate because of its low emissivity. That is, in order to discharge heat from the aluminum plate, it is only by heat conduction of air in contact with the aluminum plate, and the temperature of the aluminum plate has not been effectively reduced. Therefore, if a hole or opening for air circulation is provided in the rear case, there is a problem that not only light from the lighting device leaks from the rear case, but also the strength of the rear case decreases. Further, the air holes of the outer case are arranged so as to cool the heat generated by the circuit members behind the base plate, and do not effectively cool the heat generated by the liquid crystal display unit.

  An object of the present invention is to provide a liquid crystal display device that can effectively dissipate heat generated by a liquid crystal display unit.

  A liquid crystal display device according to the present invention includes a liquid crystal panel, an illumination device for illuminating the liquid crystal panel, and a plate-like member disposed near the illumination device, the plate-like member comprising a metal base The metal base material is at least partially covered, and has a surface portion having a higher emissivity than the metal base material.

  According to this configuration, the plate-like member of the liquid crystal display unit has a structure with high heat dissipation, and heat generated inside the liquid crystal display unit is discharged from the plate-like member to the outside by radiation. Therefore, the liquid crystal panel and the light source inside the liquid crystal display unit are cooled, and their functions can be fully exhibited. Therefore, the plate member can be made of a metal plate having high thermal conductivity and high mechanical strength.

  Furthermore, in another aspect of the present invention, a liquid crystal display device includes a liquid crystal panel, a lighting device, a liquid crystal display unit including a plate member, a base plate on which a circuit member is mounted, the liquid crystal display unit, and the liquid crystal display unit. And an outer case containing a base plate, the outer case having air holes or heat channels at positions facing the outer peripheral portion of the liquid crystal display unit.

  According to this configuration, the heat generated inside the liquid crystal display unit moves to the outside of the liquid crystal display device through the air holes or the heat flow path provided in the outer case of the liquid crystal display unit. In this case, since the air hole or the heat flow path is provided at a position facing the outer peripheral portion of the liquid crystal display unit, the heat generated inside the liquid crystal display unit is discharged from the outer case at the shortest distance. Therefore, the liquid crystal panel and the light source inside the liquid crystal display unit are cooled, and their functions can be fully exhibited.

  Furthermore, in another aspect of the present invention, a liquid crystal display device includes a liquid crystal panel, a liquid crystal display unit including a lighting device and a plate member, a base plate on which a circuit member is mounted, the liquid crystal display unit, and the base. An outer case containing a plate, and the distance between the outer peripheral surface of the liquid crystal display unit and the inner peripheral surface of the outer case facing the outer peripheral surface is 10 mm or more, and the outer case has a distance from the inside of the outer case An air hole or a heat flow path leading to the outside is provided.

  According to this configuration, the heat generated inside the liquid crystal display unit moves to the outside of the liquid crystal display unit by the flow of air flowing through the space between the liquid crystal display unit and the outer case. Therefore, the liquid crystal panel and the light source inside the liquid crystal display unit are cooled, and their functions can be fully exhibited.

  Thus, in the present invention, the plate-like member constituting the outer surface of the liquid crystal display unit is used as a surface portion having a high emissivity, or a hole is formed at the position of the outer case facing the outer peripheral surface of the liquid crystal display unit. The heat inside the liquid crystal display unit is easily moved out of the liquid crystal display unit. For this reason, it is possible to prevent a decrease in contrast, color unevenness, brightness unevenness, brightness decrease, and shortening of the life due to a temperature increase inside the liquid crystal display unit.

  In the conventional liquid crystal display device, the surface of the metal plate member forming the rear case of the liquid crystal display unit is close to the polished surface (mirror surface), and the emissivity of infrared rays having a wavelength of 4 μm to 16 μm is much lower than 0.1. For this reason, heat is transmitted through the inside of the metal plate member by conduction, but the movement due to the radiation of the heat from the metal plate member to other members is small, and the heat moves by natural air cooling using air as a medium. Only. According to the present invention, by improving the emissivity of a plate-like member such as a rear case to 0.7 or more, when the temperature of the metal plate-like member is 40 ° C. to 70 ° C., the amount of heat exhausted by radiation is air. It was found that it was several times larger than the amount of exhaust heat due to transmission. Therefore, in the liquid crystal display device that consumes a large amount of power despite the compact structure, the temperature rise inside the liquid crystal display unit can be reduced.

  As a specific example of setting the emissivity of the rear case to 0.7 or more, a material having a relatively high emissivity is bonded or applied to the surface of the metal substrate, or the metal surface has a thickness of about 2 The oxide film surface is 5 μm or more, or the metal surface is a rough surface having an average maximum height difference (PVA) of 4 μm or more.

  Preferably, a special Teflon film (emissivity of about 0.8), a graphite sheet (emissivity of about 0.75), or an opaque plastic (emissivity of about 0.95) is bonded to the metal surface. Alternatively, Okitsumo Cool Tech (emissivity of about 0.9 or more) or (white or black) paint (emissivity of about 0.8) manufactured by Okitsumo Co., Ltd. is applied to the metal surface. Other organic substances, ceramics, asbestos, carbon, etc. may be applied. Alternatively, the surface of aluminum is modified by alumite treatment (emissivity of about 0.8 or more) and metal oxidation treatment such as steel to obtain high emissivity.

  In this way, the temperature rise inside the liquid crystal display unit can be suppressed, and a display with high contrast can be realized. In particular, the temperature rise of the liquid crystal material can be suppressed, and high image quality can be maintained for a longer time.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a front view showing a liquid crystal display device. FIG. 2 is a side view showing the liquid crystal display device. FIG. 3 is a cross-sectional view showing a liquid crystal display device. The liquid crystal display device shown in FIGS. 1 to 3 can be used as a television or a monitor, for example.

  1 to 3, a liquid crystal display device 10 includes an outer case 12, a base plate 14 disposed in the outer case 12, and a liquid crystal display unit 16 fixed inside the outer case 12 by the base plate 14. Prepare. The base plate 14 is supported on the support stand 20 by the pivot structure 18.

  FIG. 4 is an exploded perspective view of the liquid crystal display device. The outer case 12 includes a front case member 12F and a rear case member 12R. The outer case 12 is made of a resin such as ABS resin, and the base plate 14 is made of a galvanized steel plate. The liquid crystal display unit 16 is disposed on the front side of the base plate 14 (see FIG. 3). Speakers 13 are disposed at both ends of the front case member 12F.

  The liquid crystal display unit 16 includes a liquid crystal panel 22, a lighting device 24 disposed behind the liquid crystal panel 26, a rear case (lamp house) 26 that houses the lighting device 24, and a front cover that partially covers the front surface of the liquid crystal panel 22. It comprises a (bezel) 28 and a resin cover 30. The liquid crystal panel 26 is formed by inserting liquid crystal between a pair of glass substrates. A polarizer is bonded to the glass substrate.

  A liquid crystal driving circuit 31 and a lighting circuit (inverter circuit) 32 are attached to the rear surface side of the rear case 26. A circuit member 34 of the apparatus is attached to the rear surface side of the base plate 14. The circuit member 34 of the apparatus includes, for example, a signal processing circuit such as a scaler, a power supply circuit, an inverter circuit (cold cathode tube driving circuit), a speaker circuit, and the like.

  FIG. 5 is a diagram showing an example of the illumination device 24 of the liquid crystal display unit. FIG. 5 shows an example of a sidelight type backlight. FIG. 6 is a perspective view showing the light source and reflector of FIG. The illumination device 24 includes a light guide plate 36 disposed behind the liquid crystal panel 22 and a light source (cold cathode tube) 38 disposed on a side portion of the light guide plate 36. The light source 38 is provided together with the reflector 40. A reflection sheet 37 is disposed on the rear surface of the light guide plate 36. Both ends of the light source 38 are attached to the reflector 40 by holding members 42 such as silicon rubber. A terminal portion 38E of the electrode of the light source 38 protrudes from the holding member 42 and is connected to a lead wire (not shown). The light source (cold cathode tube) 38 is a long fluorescent lamp, and a predetermined position (for example, the central portion in the longitudinal direction) 38C of the light source 38 is locally cooled to maintain a constant temperature, thereby improving the luminous efficiency of the light source 38. I try to keep it high.

  FIG. 7 is a cross-sectional view showing another example of the illumination device 24 of the liquid crystal display unit. FIG. 7 shows an example of a direct type backlight. FIG. 8 is a perspective view showing a light source and a support member of the liquid crystal display unit of FIG. The illumination device 24 includes a plurality of light sources (cold cathode tubes) 38 disposed behind the liquid crystal panel 22. The diffusion sheet 44 is disposed above the light source 38, and the reflection sheet (diffuse reflection sheet) 46 is disposed below the light source 38. In the sidelight type backlight, an optical sheet such as a diffusion sheet or a prism sheet can be used.

  The ends of the plurality of light sources 38 are attached to the light source support member 48 by a holding member 42 such as silicon rubber. The light source support member 48 can be a part of the rear case 26, or can be configured as a separate member from the rear case 26 and disposed inside or outside the rear case 26. The terminal portion of the electrode of the light source 38 protrudes from the holding member 42 of the light source support member 48 and is connected to a lead wire (not shown).

  FIG. 9 is a schematic view showing a rear case and a printed circuit board disposed inside the liquid crystal display device. 9A is a side view and FIG. 9B is an exploded view. The rear case 36 is disposed so as to constitute the outer surface of the liquid crystal display unit 16. A printed circuit board 50 is attached to the outer surface side of the rear case 26. A liquid crystal drive circuit 31 and an inverter circuit 32 are mounted on the printed circuit board 50.

  It is preferable that a gap through which air flows is provided between the printed board 50 and the rear case 26. For this purpose, the PT support base 51 is fixed to the rear case 26 by an adhesive (or adhesive material) 52, and the printed circuit board 50 is fixed to the PT support base 51 by screws 53. In this case, there is no need to make a hole in the rear case 26 (at least a part corresponding to the lighting device 24) or to cut and groove a part of the plate to form a projection. Therefore, it becomes easy to plate the rear case 26 in a state where the reflection sheet 46 is bonded to the rear case 26. Further, if there is no hole in the rear case 26, light does not leak from the rear case 26, the mechanical strength of the rear case 26 is not weakened, the confidentiality of the liquid crystal display unit 16 is improved, and no dust enters. If the PT support 51 is made of a material having good thermal insulation, the amount of heat transferred from the printed circuit board 50 to the rear case 26 can be reduced. Further, if the member 52 is made of an elastic member such as an adhesive tape or the PT support base 51 is made of an elastic material, the distortion of the rear case 26 due to the thermal expansion difference between the printed circuit board 50 and the rear case 26, and therefore the liquid crystal The distortion of the panel can be reduced and display unevenness can be reduced.

  1 to 3, the outer case 12 includes a front wall 12A, a rear wall 12B, and an outer peripheral wall 12C that connects the front wall 12A and the rear wall 12B. The front wall 12 </ b> A is a frame-shaped part surrounding the display unit 24. The rear wall 12B is a substantially vertical portion. The outer peripheral wall 12C has a first portion 12C1 and a second portion 12C2. The first portion 12C1 is on the side close to the front wall 12A, faces the outer peripheral portion of the liquid crystal display unit 16, and has a small inclination. The second portion 12C2 is on the side close to the rear wall 12B4 and has a large inclination. The first portion 12C1 is generally on the front side of the base plate 14. The second portion 12 </ b> C <b> 2 is in a region including the circuit member 34 mounted on the base plate 14.

  10 to 14 are views showing the characteristics of the air holes provided in the outer case of the liquid crystal display device. FIG. 10 is a side view showing the outer case. FIG. 11 is a front view showing the outer case. FIG. 12 is a rear view showing the outer case. FIG. 13 is a plan view showing the outer case. FIG. 14 is an enlarged cross-sectional view showing a portion A in FIG.

  10 to 14, a large number of minute air holes 54 are provided in the first portion 12 </ b> C <b> 1 of the outer peripheral wall 12 </ b> C of the outer case 12. In the embodiment, the air holes 54 are provided in the entire region of the first portion 12C1, that is, the upper region, the lower region, and the two side regions. However, the air holes 54 do not have to be provided in the entire region of the first portion 12C1. For example, the air holes 54 may be provided only in the upper region of the first portion 12C1, only in the upper region and the lower region, or only in the side region and the upper region.

  The first portion 12 </ b> C <b> 1 is generally on the front side of the base plate 14, faces the outer peripheral portion of the liquid crystal display unit 16, and is close thereto. Therefore, the heat generated inside the liquid crystal display unit 16 is discharged to the outside of the outer case 12 through the air hole 54 of the first portion 12C1 at the shortest distance. Therefore, the liquid crystal panel 22 and the light source 38 inside the liquid crystal display unit 16 are sufficiently cooled, and their functions can be sufficiently exhibited.

  Furthermore, a large number of minute air holes 55 are provided in the front wall 12 </ b> A of the outer case 12. The heat generated inside the liquid crystal display unit 16 is discharged to the outside of the liquid crystal display device through the air holes 55 provided in the front wall 12A of the outer case 12.

  Furthermore, a small number of air holes 56 are provided in the second portion 12C2 of the outer peripheral wall 12C of the outer case 12. The second portion 12C2 is generally on the rear side of the base plate 14, and heat generated by the circuit member 22 mounted on the base plate 14 is discharged to the outside of the liquid crystal display device through the air holes 56 of the second portion 12C2. Is done.

  FIG. 15 is a diagram showing an example of the relationship between the outer case of the liquid crystal display device and the liquid crystal display unit. In this example, as described above, the air holes 54 and 55 or the heat flow path are provided in the outer case 12 at a position near the liquid crystal display unit 16. In FIG. 15A, the distance between the outer peripheral surface of the liquid crystal display unit 16 and the opposing inner peripheral surface of the outer case 12 is relatively small, for example, about 1 mm. For this reason, in the outer case 12, the air flow is small in the space between the outer peripheral surface of the liquid crystal display unit 16 and the inner peripheral surface of the outer case 12. Therefore, the heat transfer from the liquid crystal display unit 16 to the outer case 12 is relatively small, and the amount of heat discharged to the outer case 12 is relatively small.

  15B and 15C, the distance between the outer peripheral surface of the liquid crystal display unit 16 and the inner peripheral surface facing the outer case 12 is relatively large. Therefore, a large air flow is generated in the space between the outer peripheral surface of the liquid crystal display unit 16 and the inner peripheral surface of the outer case 12 in the outer case 12. In FIG. 15B, air flows from the bottom to the top. In FIG. 15C, air flows from top to bottom. Therefore, the heat transfer from the liquid crystal display unit 16 to the outer case 12 is relatively large, and the amount of heat discharged to the outer case 12 is relatively large.

  If the distance between the outer peripheral surface of the liquid crystal display unit 16 and the opposing inner peripheral surface of the outer case 12 is 5 mm or more, the air flow is improved and the cooling effect is obtained. This distance is preferably 10 mm or more. In particular, the air flow rate increases rapidly with distance up to 10 mm, and the increase decreases when the distance exceeds 10 mm.

  For example, in FIG. 4, a large number of minute air holes are provided on the entire surface of the resin cover 30 so that heat can be transferred from the front cover 28 through the resin cover 30. Further, a 10 mm gap was provided between the resin cover 30 and the speaker housing portion of the front case member 12F, and a 10 mm gap was further provided between the resin cover 30 and the front wall 12A of the outer case 12.

  Further, at least one of the rear case 26 and the front cover 28 is processed to increase the emissivity, as will be described later. With these structures, the temperature of the liquid crystal display unit 16 can be considerably lowered by natural air cooling by air convection and radiation cooling by infrared emission. The radiated infrared rays are absorbed by the convection air, or absorbed by the opposing outer case and radiated to the outside, or directly radiated to the outside through the holes of the outer case.

  FIG. 16 is a schematic diagram showing a rear case 26 that houses the illumination device 24 of the liquid crystal display unit 16. The feature of the rear case 26 can be used for both a sidelight type backlight and a direct type backlight. FIG. 16A shows the inner surface side of the rear case 26, and FIG. 16B shows the outer surface side of the rear case 26.

  The rear case 26 is made of a metal plate (metal substrate) having high thermal conductivity and high mechanical strength. Preferably, the rear case 26 is made of 5052 series aluminum. Similarly, the front cover 28 of the liquid crystal display unit 16 is also made of 5052 series aluminum.

  The rear case 26 at least partially covers the metal substrate and has a surface portion 26A having a higher emissivity than the metal substrate. The surface portion 26A bonds a material layer having a high emissivity to a metal substrate, or applies a material layer having a high emissivity to a metal substrate, or modifies the surface of the metal substrate.

  The material bonded to the surface portion 26A is, for example, a special Teflon film (emissivity about 0.8), a graphite sheet (emissivity about 0.75), an opaque plastic (emissivity about 0.95), or the like. The material applied to the surface portion 26A is, for example, Okitsumo Cool Tech (emissivity of about 0.9 or more), (white or black) paint (emissivity of about 0.8), other organic matter, ceramic, manufactured by Okitsumo Co., Ltd. Asbestos, carbon, etc. As an example of the modification, the surface of the metal is modified by a metal oxidation treatment such as silicon carbide, anodized (emissivity of about 0.8 or more), and steel. For example, Teflon tape (Nitto Denko product), Okitsumo Cool Tech (Okitsumo product), KD Eco-Cool (Dainippon Paint product), Shellac α (Oki Electric product), etc. with high heat dissipation can be used. In particular, Teflon has high heat resistance and can withstand a maximum temperature of 180 ° C.

  In FIG. 16, the surface portion 26A of the rear case 26 is made of heat dissipating black paint applied to the outer surface of a floor-shaped or U-shaped metal base material. The surface portion 26A is indicated by hatching. The paint may be black paint or white paint. In the examples, black paint was used. The thickness of the black paint is preferably in the range of 10 to 300 μm. If the thickness of the black paint is too thin, the heat dissipation is not so high, and if the thickness of the black paint is too thick, the thermal conductivity is lowered. When white paint is applied instead of black paint, the white paint reflects light and absorbs heat, so that it can function as the surface portion 26A and also function as a reflection sheet. In the following embodiments, the surface portion 26A is described as an example in which black paint is applied to a metal base material, but the surface portion 26A may be subjected to the other treatment described above.

  When the rear case 26 was prepared and used without applying black paint at room temperature of 25 ° C., the temperature of the rear case 26 was 50 ° C. However, when the rear case 26 applied with black paint was prepared and used. The temperature of the rear case 26 reached 46 ° C. The front and back temperatures of the liquid crystal panel 26 before application were 44 ° C. and 47 ° C., but the front and back temperatures of the liquid crystal panel 22 after application were 42 ° C. and 45 ° C.

  As a result of the rear case 26 having a high emissivity and the formation of the air holes 54 and 55 in the outer case 12 described above, the liquid crystal panel, which has conventionally been at the room temperature RT, has a temperature (TL-0. 3 (TL-RT)). In particular, in the vicinity of the four corners of the liquid crystal display unit having a sidelight type backlight and the electrodes of the cold cathode fluorescent lamps nearby, the temperature of the liquid crystal panel 22 is greatly reduced to (TL-0.55 (TL-RT)). did.

  FIG. 17 is a schematic view showing another example of the rear case 26. FIG. 17A shows the inner surface side of the rear case 26, and FIG. 17B shows a cross-sectional view of the rear case 26. The rear case 26 has a surface portion 26A covering the metal base material, and the surface portion 26A is made of black paint applied to the metal base material. In this case, although the temperature of the rear case 26 slightly increased compared to the example of FIG. 16, the front and back temperature of the liquid crystal panel further decreased by about 2 ° C.

  FIG. 18 is a schematic view showing another example of the rear case 26. 18A shows a plan view of the rear case 26 together with the light source 38 and the light guide plate 36, and FIG. 18B shows a side view of the light source 38, the light guide plate 36 and the rear case 26. In this example, the surface portion 26 </ b> A (black paint) is provided in a belt-like region including the light source 38. Since the amount of heat generated in the vicinity of the light source 38 is large and the temperature is high, the surface portion 26A (black paint) is applied in this way, and an effective result is obtained. When the surface portion 26A (black paint) was applied to the inner and outer surfaces of the rear case 26, the electrode temperature dropped from 102 ° C. to 97 ° C.

  FIG. 19 is a schematic view showing another example of the rear case 26. 19A shows a plan view of the rear case 26 together with the light source 38 and the light guide plate 36, and FIG. 19B shows a side view of the light source 38, the light guide plate 36 and the rear case 26. In this example, the surface portion 26 </ b> A (black paint) is provided in a relatively small area including the electrode of the light source 38. In the vicinity of the light source 38, particularly in the vicinity of the electrode, the amount of heat generation is large and the temperature becomes high. Therefore, the surface portion 26A (black paint) was applied to the region including the electrode of the light source 38, and an effective result was obtained.

  FIG. 20 is a view showing a temperature distribution in the rear case 26. FIG. 20 shows temperature contour lines. As can be seen from FIG. 20, the amount of heat generation is large in the vicinity of the light source (cold cathode tube) 38, particularly in the vicinity of the electrode, and the temperature becomes high. Accordingly, as shown in FIGS. 18 and 19, it is effective to locally provide the surface portion 26A (black paint) so as to include the portion where the temperature is high. The surface portion 26A (black paint) is not necessarily provided in the region where the temperature is low. In this manner, in a liquid crystal display device having a sidelight type backlight, the vicinity of the four corners where the electrodes of the light source (cold cathode tube) 38 are close has high emissivity, the temperature is made uniform, and the unevenness of contrast (black luminance) Unevenness of increase and unevenness of decrease in white luminance) can be prevented.

  FIG. 21 is a schematic view showing another example of the rear case 26. This example is a liquid crystal display device having a direct type backlight. 21A shows a plan view of the rear case 26 together with the diffusion sheet 44 and the plurality of light sources 38, FIG. 21B shows a front sectional view, and FIG. 21C shows a side sectional view. A reflective sheet 46 of FIG. 7 can also be provided. In this example, the surface portion 26 </ b> A is formed in parallel stripe regions so as to be located under the light source 38.

  FIG. 22 is a schematic view showing another example of the rear case 26. This example is a liquid crystal display device having a direct type backlight. 21A shows a plan view of the rear case 26 together with the diffusion sheet 44 and the plurality of light sources 38, FIG. 21B shows a front sectional view, and FIG. 21C shows a side sectional view. A reflective sheet 46 of FIG. 7 can also be provided. In this example, the surface portion 26 </ b> A is formed in a wide area so as to be located under all the light sources 38.

  In the examples of FIGS. 21 and 22, the temperature of the light source 38 and the temperature of the electrode of the light source 38 can be reduced by 5 to 8%.

  FIG. 23 is a diagram illustrating the relationship between lighting time and luminance. Curve P shows an example of a liquid crystal display device of the present invention having a high emissivity surface portion 26A, and curve Q shows an example of a conventional liquid crystal display device having no high emissivity surface portion 26A. According to the present invention, even when the liquid crystal display device is used for a long time, there is little decrease in luminance.

  FIG. 24 is a diagram showing the relationship between lighting time and chromaticity. This example is the result of examining blue. Curve R represents an example of the liquid crystal display device of the present invention having a high emissivity surface portion 26A, and curve S represents an example of a conventional liquid crystal display device having no high emissivity surface portion 26A. According to the present invention, even when the liquid crystal display device is used for a long time, the decrease in chromaticity is small.

  FIG. 25 is a schematic view showing another example of the rear case 26. This example shows the configuration of the surface portion 26 </ b> A when the high temperature member 58 is near the rear case 26. The high temperature member 58 is a heat generating member such as the liquid crystal drive circuit 31 and the inverter circuit 32 shown in FIG. FIG. 25A shows a plan view, and FIG. 25B shows a side view. When the high temperature member 58 is near the rear case 26, the surface portion 26 </ b> A of the rear case 26 is not provided in a region facing the high temperature member 58, but only in a region excluding a region facing the high temperature member 58.

  FIG. 26 is a schematic view showing another example of the rear case 26. This example shows the configuration of the surface portion 26 </ b> A when the low temperature member 60 is near the rear case 26. The low temperature member 60 is a portion of the printed circuit board 50 excluding heat generating members such as the liquid crystal drive circuit 31 and the inverter circuit 32 shown in FIG. FIG. 26A shows a plan view, and FIG. 26B shows a side view. When the low temperature member 60 is near the rear case 26, the surface portion 26 </ b> A of the rear case 26 is also provided in a region facing the low temperature member 60. The surface portion 26A is also provided in other regions. A high emissivity surface portion 60 </ b> A is provided on the low temperature member 60. Therefore, more heat of the rear case 26 is transmitted to the low temperature member 60.

  FIG. 27 is a schematic view showing another example of the rear case 26. This example shows the configuration of the surface portion 26 </ b> A when the high temperature member 58 and the low temperature member 60 are near the rear case 26. FIG. 27A shows a plan view, and FIG. 27B shows a side view. When the high temperature member 58 and the low temperature member 60 are provided near the rear case 26, the surface portion 26 </ b> A of the rear case 26 is not provided in a region facing the high temperature member 58 but opposed to the low temperature member 60. Provide in the area. The surface portion 26A is also provided in other regions. A high emissivity surface portion 60 </ b> A is provided on the low temperature member 60.

  Thus, when there is a high temperature member 58 such as a liquid crystal panel drive circuit in the vicinity of the rear case 26, the temperature of the opposite rear case 26 increases by about 2 ° C. compared to the portion without the high temperature member 58 when paint is applied, The temperature of high-temperature electronic components on the printed circuit board decreased. At this time, the distance between the liquid crystal panel and the rear case 26 was about 10 mm, and the distance between the back surface of the rear case 26 and the printed circuit board 50 was about 0.8 mm. Therefore, it is better that the portion of the rear case 26 facing the high temperature member should be an aluminum mirror surface, and if the low temperature member 60 is facing, it is better to treat the rear case 26 with a high emissivity. It was.

  FIG. 28 is a schematic view showing another example of the rear case 26. This example shows the configuration of the surface portion 26 </ b> A in the case where there are two high temperature members 57 and 58 near the rear case 26. In this case, the surface portion 26 </ b> A of the rear case 26 is not provided in the region facing the high temperature members 57, 58, and is provided only in the region excluding the region facing the high temperature members 57, 58.

  FIG. 29 is a schematic view showing another example of the rear case 26. FIG. 29A shows a plan view, and FIG. 29B shows a side view. This example shows the configuration of the surface portion 26 </ b> A when there are two high temperature members 57 and 58 near the rear case 26 and the heat generation amount of the high temperature member 57 is larger than the heat generation amount of the high temperature member 58. The high temperature member 57 having a large heat generation amount is disposed at a position higher than the high temperature member 58 having a small heat generation amount. In this case, the surface portion 26 </ b> A of the rear case 26 is not provided in the region facing the high temperature members 57, 58, and is provided only in the region excluding the region facing the high temperature members 57, 58.

  FIG. 30 is a schematic view showing another example of the rear case 26. FIG. 30A shows a side view of an example including a high temperature member 57 having a large calorific value. In this case, the high temperature member 57 is disposed at a high position, and the surface portion 26A of the rear case 26 is not provided in a region facing the high temperature member 57 but provided only in other regions. FIG. 30B shows a side view of an example including the high temperature member 58 with a small calorific value. In this case, the high temperature member 58 may be attached to the rear case 26. The surface portion 26A of the rear case 26 is not provided in a region wider than the region of the high temperature member 58, and is provided only in a narrow region including the light source 38, for example.

  FIG. 31 is a diagram illustrating an example of a light source and a reflector. FIG. 31A is a side view, FIG. 31B is a diagram showing a light source and a cable viewed in the longitudinal direction, and FIG. 31C is a diagram showing a modification of the light source and cable viewed in the longitudinal direction. 31A and 31B, the electrode 38E of the light source 38 is connected to the connector 64 by a cable 62. In order to connect the cable 62 to the electrode 38E, the conductive wire is exposed in the portion of the cable 62 near the electrode 38E. In this example, a surface portion 62A subjected to a treatment for increasing the emissivity is provided in the exposed portion of the conducting wire in the same manner as the surface portion 26A of the rear case 26. In FIG. 31C, the electrode 38E of the light source 38 is connected to a portion where the conductor of the cable 62 is exposed by a caulking or soldering portion 66. The caulking or soldering portion 66 and the exposed portion are treated to increase the emissivity. In this case, when a Teflon tape was applied, the electrode temperature 120 ° C. decreased to 104 ° C.

  FIG. 32 is a diagram illustrating an example of a light source and a reflector. FIG. 32A is a side view, and FIG. 32B is a perspective view of the reflector. The surface portion 40A of the reflector 40 that faces the surface portion 26A of the rear case 26 is subjected to a process for increasing the emissivity in the same manner as the surface portion 26A of the rear case 26. Accordingly, the surface portion 26A and the surface portion 40A face each other, and the heat generated by the light source 38 is well discharged from the reflector 40 to the rear case 26.

  Further, when the surface portion 40A of the reflector 40 is locally provided at a position corresponding to the predetermined position 38C of the light source 38 in FIG. 6, the predetermined position 38C of the light source 38 is locally cooled, and the light source 38 It is possible to maintain high emission characteristics. In this way, by applying heat-dissipating Teflon tape to the surfaces of the reflector 40 and the rear case 26 that come into contact with each other, the temperature of the light emitting part of the light source 38 can be reduced by 13% and the surface temperature of the liquid crystal panel can be reduced by 4%. it can.

  FIG. 33 is a schematic view showing another example of the rear case 26. FIG. 33A shows a plan view, and FIG. 33B shows a side view. In this example, the surface portion 26 </ b> A of the rear case 26 is provided in a belt shape that passes through the central portion of the light source 38 and crosses the light source 38.

  FIG. 34 is a schematic view showing another example of the rear case 26. 34A shows a plan view, and FIG. 34B shows a side view. In this example, the surface portion 26 </ b> A of the rear case 26 is provided locally in the region of the side edge portion of the light guide plate 36 through the central portion of the light source 38.

  FIG. 35 is a schematic view showing another example of the rear case 26. FIG. 35A shows a plan view, FIG. 35B shows a front view, and FIG. 35C shows a side view. In this example, the surface portion 26 </ b> A of the rear case 26 is provided in a band shape that crosses the light source 38 through the central portion of the plurality of light sources 38.

  In this way, by performing the process of increasing the emissivity on the rear case 26 and / or the reflector 40 near the center of the light source 38, the temperature of the light source 38 in the vicinity can be lowered from 68 ° C. to 61 ° C., and about 7 ° C. from the other portions. I was able to decrease.

  As a result, mercury can be collected in this portion in the light source 38, and a mercury vapor pressure that gives almost the maximum emission luminance (a mercury vapor pressure near a temperature of 60 ° C. gives the maximum emission luminance) can be realized in the entire tube. Realizes a 5% brightness increase in the entire tube. In particular, since the mercury particles adsorbed on the glass wall surface due to vibration during transportation do not fall, the structure in which the light source is horizontal in use is stable, and a long life and high luminance can be realized.

  FIG. 36 is a schematic view showing an example of a liquid crystal display device provided with a fan. FIG. 36A is a schematic diagram illustrating a liquid crystal display device, and FIG. 36B is a diagram illustrating a fan. A fan 68 is provided in the outer case 12 of the liquid crystal display device 10. The fan 68 is preferably arranged so as to face the surface portion 26 </ b> A of the rear case 26. If there is a fan 68, air flows as shown by the arrows. Therefore, heat is also exhausted by the air flow. Here, if the component of the fan 68 has been subjected to a process for increasing the emissivity in the same manner as the surface portion 26 </ b> A of the rear case 26, the heat that has reached the fan 68 is more efficiently discharged from the fan 68. The fan 68 has a gap between the blades, and a part of the heat radiated from the surface portion 26A of the rear case 26 is discharged out of the outer case 12 through the gap between the blades of the fan 68 and the blades. Is done. Therefore, an opening may be provided in the outer case 12 so as to face the surface portion 26 </ b> A of the rear case 26 instead of the fan 68.

  In the present invention, in a television housing a liquid crystal unit 16 including a liquid crystal panel 22 and a lighting device (backlight) 24, a speaker 13, and a processing circuit such as a scaler, there is an air intake at the bottom of a thin internal space, There is an air outlet at the top, and an exhaust fan 68 is provided at the air outlet. When the rear case 26 is disposed at a position that is particularly deep behind the fan 68, the position where the rear case 26 is located becomes an air retention point, so that heat is very difficult to escape. Therefore, when a high emissivity Teflon tape was applied to the surface of the rear case 26, the temperature of 53 ° C. decreased to 47 ° C. The reason why the effect was great is considered to be that the counter object is the air-cooling fan 68 that is cooled, and a large amount of infrared radiation is directly emitted to the outside.

  FIG. 37 is a view showing an example of the front cover shown in FIG. The front cover 28 has a surface portion 28 </ b> A, and has been subjected to a process for increasing the emissivity similarly to the surface portion 26 </ b> A of the rear case 26. In FIG. 37, the surface portion 28 </ b> A is provided entirely on the inner surface and the outer surface of the front cover 28.

  FIG. 38 is a view showing an example of the front cover. The front cover 28 has a surface portion 28 </ b> A, and has been subjected to a process for increasing the emissivity similarly to the surface portion 26 </ b> A of the rear case 26. In FIG. 38, the surface portion 28 </ b> A is provided at the four corner portions of the inner surface and the outer surface of the front cover 28.

  37 and 38 is cooled in the same manner as the rear case 26 having the surface portion 26A.

  The example described above includes the following features.

  (Supplementary Note 1) A liquid crystal panel, an illumination device for illuminating the liquid crystal panel, and a plate-like member disposed near the illumination device, the plate-like member comprising a metal base, A liquid crystal display device characterized by having a surface portion that at least partially covers a base material and has a higher emissivity than the base material of the metal.

  (Supplementary note 2) The liquid crystal display device according to supplementary note 1, wherein the surface portion comprises a portion having an emissivity of 0.7 or more.

  (Supplementary note 3) The liquid crystal display device according to supplementary note 1, wherein the surface portion includes one of a bonding layer, a coating layer, and a modified layer.

  (Supplementary note 4) The liquid crystal display device according to supplementary note 1, wherein the plate-like member includes a rear case configured to accommodate the illumination device.

  (Additional remark 5) This illuminating device is equipped with a light guide plate and the light source arrange | positioned at the side part of this light guide plate, The liquid crystal display device of Additional remark 4 characterized by the above-mentioned.

  (Supplementary note 6) The liquid crystal display device according to supplementary note 4, wherein the lighting device includes a plurality of light sources arranged between the rear case and the liquid crystal panel.

  (Supplementary note 7) The liquid crystal display device according to supplementary note 1, wherein the plate-like member includes a front cover that partially covers a front surface of the liquid crystal panel.

  (Supplementary Note 8) The plate-like member includes a rear case configured to accommodate the lighting device, and further includes a front cover partially covering the front surface of the liquid crystal panel, the front cover including a metal base, 2. The liquid crystal display device according to appendix 1, wherein the liquid crystal display device has a surface portion that at least partially covers a metal base material and has a higher emissivity than the metal base material.

  (Supplementary note 9) The liquid crystal display device according to supplementary note 1, wherein the surface portion is formed on at least one of an inner surface and an outer surface of the metal base material.

  (Supplementary note 10) The liquid crystal display device according to supplementary note 1, wherein the surface portion is at least partially formed on at least one of an inner surface and an outer surface of the metal substrate.

  (Supplementary note 11) Further, a circuit board is provided on the outer surface side of the plate-like member, and the surface portion is a portion of the plate-like member facing the circuit board or an electric member mounted on the circuit board. 2. The liquid crystal display device according to appendix 1, wherein the liquid crystal display device is provided in a portion of the plate-like member excluding the portion of the plate-like member that faces the liquid crystal display device.

  (Additional remark 12) The electrode part exposed from the glass of the light source of the illuminating device, the part to be connected such as soldering and caulking to connect the conductive wire to the electrode part, or the part of the metal wire from which the coating has been peeled off 2. The liquid crystal display device according to appendix 1, wherein the liquid crystal display device has a high emissivity structure.

  (Supplementary note 13) The illuminating device includes a light source and a reflector that partially surrounds the light source, and the surface portion is formed in a portion of the plate-like member facing the reflector. Liquid crystal display device.

  (Supplementary note 14) The illuminating device includes a light source and a reflector that partially surrounds the light source, and a portion of the reflector that faces the plate-like member is added with a structure having a high emissivity. A liquid crystal display device according to 1.

  (Supplementary note 15) The liquid crystal display according to supplementary note 1, wherein the light source of the illumination device is a cold cathode tube, and a predetermined position of the cold cathode tube is set at a lower temperature than other positions. apparatus.

  (Supplementary note 16) The liquid crystal display device according to supplementary note 1, further comprising an air cooling fan, wherein the surface portion is provided at a position near the air cooling fan.

  (Additional remark 17) Furthermore, it has an outer case which accommodates this liquid crystal panel, this illuminating device, and this plate-shaped member, and this outer case has a hole in the position facing at least one part of this surface part. 2. The liquid crystal display device according to appendix 1, which is characterized.

  (Supplementary Note 18) A liquid crystal display unit including a liquid crystal panel, a lighting device, and a plate member, a base plate on which a circuit member is mounted, and an outer case containing the liquid crystal display unit and the base plate, The outer case has an air hole or a heat flow path at a position facing the outer peripheral portion of the liquid crystal display unit.

  (Supplementary Note 19) The air holes or heat flow paths are formed in the outer case portion facing the upper portion of the liquid crystal display unit, the upper case portion facing the upper and side portions of the liquid crystal display unit, and the upper and lower portions of the liquid crystal display unit. Item 19. The liquid crystal display device according to appendix 18, wherein the liquid crystal display device is provided on at least one of the opposing outer case portions.

  (Supplementary note 20) The liquid crystal display device according to supplementary note 18, wherein the air hole or the heat flow path is provided in a portion of the outer case in front of the liquid crystal display unit.

  (Supplementary note 21) The liquid crystal display device according to supplementary note 18, wherein the air hole or the heat flow path is further provided on a front wall of the outer case.

  (Supplementary Note 22) A liquid crystal display unit including a liquid crystal panel, a lighting device, and a plate member; a base plate on which a circuit member is mounted; and an outer case housing the liquid crystal display unit and the base plate. The distance between the outer peripheral surface of the display unit and the inner peripheral surface of the outer case facing the outer peripheral surface is 10 mm or more, and the outer case is provided with an air hole or a heat flow path leading from the inside of the outer case to the outside. A liquid crystal display device.

  As described above, according to the present invention, a liquid crystal display device having good durability and excellent display quality can be obtained.

FIG. 1 is a front view showing a liquid crystal display device. FIG. 2 is a side view showing the liquid crystal display device. FIG. 3 is a cross-sectional view showing a liquid crystal display device. FIG. 4 is an exploded perspective view of the liquid crystal display device. FIG. 5 is a cross-sectional view showing an example of a lighting device of a liquid crystal display unit. FIG. 6 is a perspective view showing the light source and reflector of FIG. FIG. 7 is a cross-sectional view showing another example of a lighting device of a liquid crystal display unit. FIG. 8 is a perspective view showing the light source and the support member of FIG. FIG. 9 is a schematic view showing a rear case and a printed circuit board disposed inside the liquid crystal display device. FIG. 10 is a side view showing an outer case provided with air holes for cooling. FIG. 11 is a front view showing the outer case. FIG. 12 is a rear view showing the outer case. FIG. 13 is a plan view showing the outer case. FIG. 14 is an enlarged sectional view of a portion A in FIG. FIG. 15 is a diagram showing an example of the relationship between the outer case of the liquid crystal display device and the liquid crystal display unit. FIG. 16 is a schematic view showing a rear case containing a light source of a liquid crystal display unit. FIG. 17 is a schematic view showing another example of the rear case. FIG. 18 is a schematic view showing another example of the rear case. FIG. 19 is a schematic view showing another example of the rear case. FIG. 20 is a view showing a temperature distribution in the rear case. FIG. 21 is a schematic view showing another example of the rear case. FIG. 22 is a schematic view showing another example of the rear case. FIG. 23 is a diagram illustrating the relationship between lighting time and luminance. FIG. 24 is a diagram showing the relationship between lighting time and chromaticity. FIG. 25 is a schematic view showing another example of the rear case. FIG. 26 is a schematic view showing another example of the rear case. FIG. 27 is a schematic view showing another example of the rear case. FIG. 28 is a schematic view showing another example of the rear case. FIG. 29 is a schematic view showing another example of the rear case. FIG. 30 is a schematic view showing another example of the rear case. FIG. 31 is a diagram illustrating an example of a light source and a reflector. FIG. 32 is a diagram illustrating an example of a light source and a reflector. FIG. 33 is a schematic view showing another example of the rear case. FIG. 34 is a schematic view showing another example of the rear case. FIG. 35 is a schematic view showing another example of the rear case. FIG. 36 is a schematic view showing an example of a liquid crystal display device provided with a fan. FIG. 37 shows an example of a front cover. FIG. 38 is a view showing an example of the front cover.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display device 12 ... Outer case 14 ... Base plate 16 ... Liquid crystal display unit 22 ... Liquid crystal panel 24 ... Illumination device 26 ... Rear case 26A ... Surface part 28 ... Front cover 36 ... Light guide plate 38 ... Light source 40 ... Reflector 54 ... Air Hole 55 ... Air hole 56 ... Air hole

Claims (19)

  A liquid crystal panel, an illumination device for illuminating the liquid crystal panel, and a plate-like member disposed near the illumination device, the plate-like member comprising at least a metal base material and the metal base material A liquid crystal display device, characterized by having a surface portion that partially covers and has a higher emissivity than the metal substrate.   The liquid crystal display device according to claim 1, wherein the surface portion is a portion having an emissivity of 0.7 or more.   The liquid crystal display device according to claim 1, wherein the surface portion includes one of a bonding layer, a coating layer, and a modified layer.   The liquid crystal display device according to claim 1, wherein the plate-like member includes a rear case configured to accommodate the lighting device.   2. The liquid crystal display device according to claim 1, wherein the plate-like member comprises a front cover that partially covers the front surface of the liquid crystal panel.   The plate-like member includes a rear case configured to accommodate the lighting device, and further includes a front cover that partially covers the front surface of the liquid crystal panel. The front cover includes a metal base and the metal base. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a surface portion that covers at least partly and has a higher emissivity than the metal base material.   The liquid crystal display device according to claim 1, wherein the surface portion is formed on at least one of an inner surface and an outer surface of the metal base material.   The liquid crystal display device according to claim 1, wherein the surface portion is at least partially formed on at least one of an inner surface and an outer surface of the metal base material.   The circuit board further includes a circuit board disposed on the outer surface side of the plate-like member, and the surface portion of the plate-like member facing the circuit board or the board facing the electric member mounted on the circuit board. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is provided on a portion of the plate-like member excluding a portion of the member.   The electrode part exposed from the glass of the light source of the illuminating device, the part connected to the electrode part such as soldering or caulking, or the part of the metal wire stripped from the conductor has a high emissivity. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a structure.   2. The liquid crystal display according to claim 1, wherein the illumination device includes a light source and a reflector partially surrounding the light source, and the surface portion is formed on a portion of the plate member facing the reflector. apparatus.   2. The liquid crystal display device according to claim 1, wherein the light source of the illuminating device is a cold cathode tube, and a predetermined position of the cold cathode tube is set to be lower in temperature than other positions.   The liquid crystal display device according to claim 1, further comprising an air cooling fan, wherein the surface portion is provided at a position near the air cooling fan.   The liquid crystal panel, the illuminating device, and the plate member are further provided with an outer case, and the outer case has a hole at a position facing at least a part of the surface portion. Item 2. A liquid crystal display device according to item 1.   A liquid crystal display unit including a liquid crystal panel, an illuminating device, and a plate member; a base plate on which a circuit member is mounted; and an outer case containing the liquid crystal display unit and the base plate. A liquid crystal display device having an air hole or a heat flow path at a position facing the outer peripheral portion of the liquid crystal display unit.   The air hole or the heat flow path includes an outer case portion facing the upper portion of the liquid crystal display unit, an outer case portion facing the upper and side portions of the liquid crystal display unit, and an outer case facing the upper and lower portions of the liquid crystal display unit. The liquid crystal display device according to claim 15, wherein the liquid crystal display device is provided in at least one of the portions.   The liquid crystal display device according to claim 15, wherein the air hole or the heat flow path is provided in a portion of the outer case in front of the liquid crystal display unit.   The liquid crystal display device according to claim 18, wherein the air hole or the heat flow path is further provided on a front wall of the outer case.   A liquid crystal display unit including a liquid crystal panel, a lighting device, and a plate member; a base plate on which a circuit member is mounted; and an outer case housing the liquid crystal display unit and the base plate. The distance between the surface and the inner peripheral surface of the outer case facing the outer peripheral surface is 10 mm or more, and the outer case is provided with an air hole or a heat flow path leading from the inside of the outer case to the outside. A characteristic liquid crystal display device.

Images