JP2005285714A - Backlight device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformly maintain the luminance of a backlight device by eliminating the generation of wrinkles by preventing a diffusion plate from depressing an optical sheet even if the diffusion plate is warped by humidity or the like. <P>SOLUTION: In the backlight device, a light source is arranged at the internal bottom face of a reflecting plate base plate 2 and a diffusion plate 4 and a plurality of optical sheets 5 are arranged in front of the light source, and the diffusion plate 4 and the optical sheets 5 are hung and supported by being engaged with an installation hole formed at the upper end of the diffusion plate 4 and the optical sheets 5 with a pin-shape projection provided at the upper end front of the reflecting plate base plate 2. A small diameter hole 18 is formed at the back side of the installation hole of the diffusion plate 4 and a large diameter hole 19 is formed at the front side, and by a hanging pin 11 having a small diameter 13 and a large diameter 14 corresponding to those different diameters, the diffusion plate 4 and the optical sheet 5 are hung. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device used as a light source for a liquid crystal television and the like. It is related with the backlight apparatus which can obtain uniform brightness | luminance and can obtain in this way.

Conventionally, a backlight device used for a liquid crystal display device such as a liquid crystal television has a diffusion plate made of an acrylic plate or the like disposed in front of a fluorescent lamp as a light source, and an ITO sheet, a diffusion film, a prism sheet, a reflective polarizing film in front of the diffusion plate Etc. are laminated. Since these diffusing plates and optical sheets are made of different materials, their respective expansion rates are different. Therefore, each time the backlight device is turned on, the temperature rises and expands with different elongation amounts. At this time, if the optical sheets are in close contact with each other, a phenomenon of warping to one side occurs like bimetal, and wrinkles occur. When wrinkles occur, the shadow of the wrinkles is reflected on the liquid crystal panel in front of the wrinkles, resulting in uneven brightness. Conventionally, as a countermeasure, when the irradiation surface of the backlight device is supported vertically, a plurality of pins are provided on the abutting surface of the reflector base plate with which the upper end of the diffusing plate abuts, and a hole is formed at the upper end. The formed diffusion plate and each optical sheet were locked to the pins, and the diffusion plate and each optical sheet were held in a state suspended by their own weight. FIG. 3 is a vertical cross-sectional view of the upper part of the backlight device for a liquid crystal display device, and shows a cross section between the pins for suspending the diffusion plate and the optical sheet. Reference numeral 1 denotes a chassis formed by die casting. A reflector base plate 2 in which a metal plate is formed in a shallow box shape is supported inside a front surface, and a reflector sheet 3 made of a white resin is supported inside the chassis. Yes. A diffusion plate 4 and a plurality of optical sheets 5 are overlapped and supported on the vertical surface portion of the edge of the reflector base plate 2. The forefront surface of the optical sheet 5 is held by a pressing metal fitting 6 having a cross-sectional crank shape with a slight gap in the thickness direction. The pressing metal 6 is fixed to the front surface of the chassis 1 with screws 7. A liquid crystal panel 8 is disposed in front of the optical sheet 5. In this state, the optical sheets 5 are held so as to freely expand and contract with each other without applying an external force in the thickness direction to the optical sheets 5. Moreover, there is a liquid crystal display device described in Patent Document 1 as a technique for holding the end portions of these optical sheets without generating wrinkles.
JP-A-11-281966

  By the way, in the backlight device of a liquid crystal display device, the generation of wrinkles of the optical sheet is influenced by the moisture of the diffusion plate supported on the back surface of the optical sheet. In other words, the atmosphere in which the backlight device is placed is not completely dry air, but contains an amount of moisture or moisture that increases or decreases depending on the weather of the day, which is absorbed by the diffusion plate having water absorption. The amount of moisture absorbed by the diffusion plate varies depending on the humidity of the atmosphere of the day and the temperature of the diffusion plate itself. In particular, when the backlight device is turned on, a temperature gradient is generated between the front surface side and the back surface side of the diffusion plate, and the amount of moisture absorbed is greatly different between the front surface side and the back surface side. As a result, there occurs a phenomenon in which the difference in expansion amount due to water absorption increases between the front surface side and the rear surface side of the diffusion plate and warps to one side. This phenomenon is also affected by the thermal expansion due to the temperature gradient on the front and back sides of the diffuser, which can lead to complex behavior, but in the normal operating environment, the central part of the diffuser swells forward and reacts. As a result, the peripheral portion of the diffusion plate tends to warp backward. Thus, when the diffusion plate is warped, the optical sheet supported by natural suspension on the front surface of the diffusion plate is sandwiched between the liquid crystal panel disposed on the front surface and freely extends. I can't. Also, because the periphery of the diffusion plate is warped, part of it is deformed forward and part of it is rearwardly deformed, and the optical sheet supported by the holding metal fitting together with the diffusion plate is pressed against the diffusion plate and can move freely. Disappear. As a result, the thermally expanded portion of the optical sheet became wrinkled, and a shadow was reflected on the liquid crystal panel on the front surface of the optical sheet, resulting in a problem of uneven brightness. Therefore, the present invention focuses on the part where the diffuser plate and the optical sheet are suspended by the pins, and prevents the diffuser plate from pressing the optical sheet even if the diffuser plate warps due to moisture or the like, thereby eliminating wrinkles. Therefore, an object of the present invention is to propose a backlight device capable of obtaining uniform luminance.

  In order to solve the above problems, the present invention provides a light source and a backlight device in which a diffusion plate and a plurality of optical sheets are overlapped and supported in front of the light source, and the diffusion plate and the optical sheet are provided in a plurality of stages. It is characterized by being suspended by a suspension pin having a diameter. Further, the present invention provides a backlight device in which a diffusion plate and a plurality of optical sheets are overlapped and supported in front of the light source, and the diffusion plate and the optical sheet are provided by a suspension pin having a plurality of diameters. It is hung, and at least the diffusion plate and the optical sheet are hung at portions having different diameters. Further, the present invention provides a backlight device in which a light source and a diffusion plate and a plurality of optical sheets are overlapped and supported in front of the light source, and the suspension pin has a two-stage diameter. Mounting holes having different diameters are provided, and the diffusion plate and the optical sheet are suspended from the suspension pin. Further, the present invention provides a light source on the inner bottom surface of the case, and arranges a diffuser plate and a plurality of optical sheets in front of the light source, and a pin-like protrusion protruding on the front surface of the upper end of the case. In a backlight device in which the attachment holes formed at the upper ends of the diffusion plate and the optical sheet are engaged and the diffusion plate and the optical sheet are suspended and supported, the back side of the attachment hole of the diffusion plate is made small in diameter and the surface side is made large. The diffusion plate and the optical sheet are suspended by suspension pins that are formed in diameters and have two-stage diameters corresponding to the different diameters. Specifically, a light source is disposed on the inner bottom surface of the shallow case, and a diffuser plate and a plurality of optical sheets are disposed in front of the light source, and a pin-like protrusion protruding from the front surface of the upper end of the case, In the backlight device that supports the suspension plate and the optical sheet by hanging the mounting holes formed at the upper ends of the diffusion plate and the optical sheet, the screw hole formed on the front surface of the upper end portion of the case, and the tip Forming a male screw portion to be screwed into the screw hole, forming a small diameter portion one step larger in diameter than the male screw portion behind the male screw portion, and one step larger diameter than the small diameter portion behind the small diameter portion. A suspension pin in which a large-diameter portion is formed, and a flange portion having a larger diameter than that of the large-diameter portion is formed behind the large-diameter portion, and a small-diameter portion of the suspension pin is disposed on the upper end of the diffusion plate with the back side. A slightly larger diameter than the front side A two-stage mounting hole formed with a larger diameter than the large-diameter portion, and an attachment hole formed with a diameter larger than the large-diameter portion of the suspension pin at the upper end of each optical sheet, The large-diameter portion of the suspending pin is inserted into the mounting hole of the optical sheet, the large-diameter portion and the small-diameter portion of the suspending pin are inserted into the two-stage mounting hole of the diffusion plate, and then the male screw portion of the suspending pin is Screw into the screw hole.

Here, in a state where the diffusion plate is suspended from the suspension pin, the length of the back side hole of the two-stage mounting hole of the diffusion plate is made shorter than the length of the small diameter portion of the suspension pin. Thus, it is preferable that the diffusion plate is not pressed against the step surface at the boundary between the small diameter portion and the large diameter portion of the suspension pin. Similarly, in a state where the diffusion plate and the optical sheet are suspended from the suspension pin, the dimension of the thickness of all the optical sheets and the length of the hole on the surface side of the two-stage mounting hole of the diffusion plate, It is preferable that the length of the large diameter portion of the suspension pin is increased so that the diffusion plate and the optical sheet are not pressed against the flange portion of the suspension pin.

  As described above, according to the present invention, the diffusion plate is formed by the suspension pin having a two-stage diameter corresponding to these different diameters, with the back surface side of the mounting hole of the diffusion plate having a small diameter and the surface side having a large diameter. And the optical sheet is suspended, the diffusion plate warps due to moisture absorption, etc., and the end portion is blocked by the stepped portion of the suspension pin even if it moves in the thickness direction. Clamping is eliminated. As a result, the free stretchability of the end portion of the optical sheet is ensured, the occurrence of wrinkling of the optical sheet is reduced, and a backlight device with stable brightness can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing an upper suspension part of a backlight device according to the present invention, and FIG. 2 is an exploded cross-sectional view showing a main part of FIG. In FIG. 1, reference numeral 1 denotes a chassis formed by die-casting. A reflection plate base plate 2 in which a metal plate is formed in a shallow box shape is supported on the inside of the front surface, and a reflection sheet 3 made of a white resin is arranged on the inside. Is supported. A diffusion plate 4 and a plurality of optical sheets 5 are overlapped and supported on the vertical surface portion of the edge of the reflector base plate 2. A liquid crystal panel 8 is disposed in front of the optical sheet 5. Here, the diffusion plate 4 and the plurality of optical sheets 5 are suspended and supported by the suspension pins 11.

As shown in FIG. 2, the hanging pin 11 has a male screw portion 12 formed at the tip, a small-diameter portion 13 larger in diameter than the male screw portion 12 at the rear, and a small-diameter at the rear of the small-diameter portion 13. A large diameter portion 14 having a larger diameter than the portion 13 is formed, and a flange portion 15 having a diameter larger than that of the large diameter portion 14 is formed behind the large diameter portion 14. The male screw portion 12 at the front end is screwed into a screw hole 16 formed near the upper end of the reflector base plate 2 and the chassis 1. The small-diameter portion 13 and the large-diameter portion 14 are inserted through a two-stage mounting hole formed in the upper end portion of the diffusion plate 4. The two-stage mounting hole of the diffusing plate 4 includes a small-diameter hole 18 on the back surface side and a large-diameter hole 19 on the surface side. The small-diameter hole 18 is slightly larger than the small-diameter portion 13, and the large-diameter hole 19 is larger than the large-diameter portion 14. The small diameter portion 13 has a margin that allows the diffusion plate 4 to move in a direction parallel to the surface when the diffusion plate 4 is engaged with the suspension pin 11. doing.

A plurality of optical sheets 5 having attachment holes 20 slightly larger than the diameter are inserted into the large-diameter portion 14 of the hanging pin 11. At this time, the length of the large-diameter portion 14 is slightly longer than the dimension of the total thickness of the plurality of optical sheets 5 and the thickness of the large-diameter hole 19 portion of the two-stage mounting hole of the diffusion plate 4. 5 is supported so as not to be pinched between the diffusion plate 4 and the flange portion 15 of the hanging pin 11. Since the suspending pin 11 is configured in this way, even if the diffusion plate 4 warps due to moisture absorption or the like and the end portion tries to move forward in the thickness direction, the small-diameter portion 13 and the large-diameter portion of the suspending pin 11 Therefore, the optical sheet 5 is eliminated from being pressed by the diffusion plate 4.

As a result, the free stretchability of the end portion of the optical sheet 5 is ensured, the generation of wrinkles in the optical sheet 5 is reduced, and a backlight device having a stable brightness can be obtained. In the illustrated example, the suspending pin 11 is used for a portion that supports the upper end portions of the diffusion plate 4 and the optical sheet 5. It is also possible to attach. At this time, the mounting holes for the diffusion plate 4 and the optical sheet 5 are enlarged in view of the allowance for expansion of the diffusion plate 4 and the optical sheet 5.

  The present invention can be used not only for suspending the upper ends of the diffusion plate and the optical sheet in the backlight device, but also for supporting the left and right ends and the lower end of the diffusion plate and the optical sheet.

It is sectional drawing which shows the upper suspension part of the backlight apparatus which concerns on this invention. It is sectional drawing which decomposed | disassembled and showed the principal part of FIG. It is sectional drawing which shows a prior art example.

Explanation of symbols

1 Chassis

2 Reflector base plate

3 Reflective sheet

4 Diffuser

5 Optical sheet

8 LCD panel

11 Hanging pin

12 Male thread

13 Small diameter part

14 Large diameter part

15 Flange

16 Screw holes

18 Small hole

19 Large diameter hole

20 Mounting hole

Claims (6)

In a backlight device that supports a light source and a diffusing plate and a plurality of optical sheets that are suspended and supported in front of the light source,

The backlight device characterized in that the diffusion plate and the optical sheet are suspended by suspension pins having a plurality of stages of diameters. In a backlight device that supports a light source and a diffusing plate and a plurality of optical sheets that are suspended and supported in front of the light source,

The backlight device, wherein the diffusion plate and the optical sheet are suspended by suspension pins having a plurality of stages of diameters, and at least the diffusion plate and the optical sheet are suspended at portions having different diameters. In a backlight device in which a light source and a diffusion plate and a plurality of optical sheets are overlapped and supported in front of the light source, the suspension pin has a two-stage diameter, and the diffusion plate has two different diameters. A backlight device having an attachment hole, wherein the diffusion plate and the optical sheet are suspended from the suspension pin. A light source is disposed on an inner bottom surface of the case, and a diffusion plate and a plurality of optical sheets are disposed in front of the light source, and the diffusion plate and the optical sheet are disposed on a pin-shaped protrusion protruding from the front surface of the upper end of the case. In the backlight device that is supported by hanging the diffusion plate and the optical sheet by engaging a mounting hole formed at the upper end of

A screw hole formed in the front surface of the upper end of the case;

A male threaded portion that is screwed into the screw hole is formed at the tip, a small diameter portion that is one step larger in diameter than the male threaded portion is formed behind the male threaded portion, and one step larger than the small diameter portion is disposed behind the small diameter portion. A hanging pin that forms a large-diameter portion of a diameter, and has a flange portion that is one step larger in diameter than the large-diameter portion behind the large-diameter portion;

A two-stage mounting hole formed at the upper end of the diffusion plate with the back side slightly larger in diameter than the small-diameter portion of the suspension pin and the surface side larger in diameter than the large-diameter portion;

An attachment hole formed at the upper end of each optical sheet with a diameter larger than the large diameter portion of the suspension pin;

The suspension pin is inserted into the mounting hole of the optical sheet, the large diameter portion and the small diameter portion of the suspension pin are inserted into the two-stage mounting hole of the diffusion plate, and then the suspension pin The backlight device is characterized in that the male screw portion of the screw is screwed into the screw hole. The backlight device according to claim 4, wherein

In a state where the diffusion plate is suspended from the suspension pin, the length of the back side hole of the two-stage mounting hole of the diffusion plate is made shorter than the length of the small diameter portion of the suspension pin, A backlight device characterized in that the diffusing plate is not pressed against the step surface at the boundary between the small diameter portion and the large diameter portion of the suspension pin. The backlight device according to claim 4 or 5,

In a state in which the diffusion plate and the optical sheet are suspended from the suspension pin, the suspension is more than the dimension obtained by combining the thickness of all the optical sheets and the length of the hole on the surface side of the two-stage mounting hole of the diffusion plate. The backlight device characterized in that the length of the large-diameter portion of the lowering pin is increased so that the diffusion plate and the optical sheet are not pressed against the flange portion of the hanging pin.

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