JP2007316421A - Illuminator and display device with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illuminator which can convert light from a linear light source or the like to surface light, that is, can eliminate a light source image even when the number of optical sheets is reduced and can secure satisfactory front luminance. <P>SOLUTION: Since only a diffusion plate 6 having a fluorescence layer for converting UV into visible light is disposed in a light irradiation path between a light source 7 and a display panel 3, high luminance surface light emission is made possible by diffusion of light source light and illumination of the fluorescence layer and the light source image can be eliminated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illuminating device suitably used for a display device including a transmissive display panel.

  As an example of a flat display device, for example, a liquid crystal display device including a transmissive liquid crystal display panel generally has an illumination device disposed on the back side of the liquid crystal display panel. This illuminating device is a device that includes a linear light source such as a cold cathode tube as a light source, and adjusts the characteristics of light emitted from the linear light source and irradiates the back side of the display panel. The irradiated light is transmitted through the display panel, whereby an image is displayed in a visible state on the front side of the display panel.

  FIG. 3 is an exploded perspective view schematically showing a main part of the structure of a liquid crystal display device generally used conventionally. The illustrated liquid crystal display device 30 includes a bezel 31, a display panel 32, and a lighting device 33. The bezel 31 is a member that serves as a frame of the display panel 32. The display panel 32 is formed by bonding two glasses and sealing liquid crystal therebetween.

  The illustrated illumination device 33 includes an optical sheet 34, a diffusion plate 35, a linear light source 36, a reflection plate 37, and a chassis 38. The optical sheet 34 and the diffusing plate 35 are for adjusting the characteristics of light incident on the display panel 32 from the linear light source 36.

  Specifically, the diffusing plate 5 has a plate shape with a thickness of about 2 mm, and diffuses light from the linear light source 36 to make the luminance distribution uniform. Each of the three optical sheets 34 has a sheet shape with a thickness of 0.1 mm to 0.3 mm. For example, in order from the bottom, a diffusion sheet 34c, a lens sheet 34b, and a brightness enhancement sheet 34a are formed. 35 are placed on top of each other. The diffusion sheet 34c is for further diffusing the light emitted from the diffusion plate 35 to make the luminance distribution more uniform. The lens sheet 34b is for increasing the front luminance by condensing the light emitted from the diffusion sheet 34c. The brightness enhancement sheet 34a is for selectively reflecting light without being absorbed by the lower deflection plate of the display panel.

  With such a diffusion plate 35 and optical sheets 34a to 34c, linear light emitted from each linear light source 36 can be converted into planar light, that is, the image of the light source can be erased to irradiate the liquid crystal panel. .

  In addition, the following patent document 1 is mentioned as a prior art document relevant to this invention.

JP-A-6-273762

  However, in particular, a plurality of optical sheets 34 occupy most of the cost of the illumination device 33, and it is considered to reduce the cost by reducing these optical sheets 34. There is a problem that reduction is difficult because it is essential for increasing the front luminance and for converting light from a linear light source such as a cold-cathode tube into planar light.

  Therefore, the problem to be solved by the present invention is that even if the optical sheet is reduced, light from a linear light source or the like can be converted into planar light, that is, the light source image can be erased, and sufficient front luminance can be obtained. It is providing the illuminating device which can be ensured.

  In order to solve the above problems, the illumination device according to the present invention includes only a diffusion plate having a fluorescent layer for converting ultraviolet light into visible light in the light irradiation path between the light source and the display panel. The gist of this is.

  In this case, the diffusion plate includes a base material and a diffusion layer provided on the surface of the base material on the display panel side, and the fluorescent layer is visible in the base material or the diffusion layer. It is preferable that the phosphor for conversion into light is dispersed. Further, the diffusion plate is configured to include a base material, a diffusion layer provided on the display panel side surface of the base material, and a fluorescent layer provided on the light source side surface of the base material. good.

  Furthermore, it is preferable that an ultraviolet cut filter is not provided in the light irradiation path from the light source to the diffusion plate.

  And it is good to set it as the structure which is a display apparatus provided with such an illuminating device.

  According to the illuminating device having the above configuration, the light irradiation path between the light source and the display panel has a configuration in which only a diffusion plate having a fluorescent layer for converting ultraviolet light into visible light is disposed. The light emitted from the fluorescent layer and the fluorescent layer emits light, whereby high luminance surface emission is possible, and the linear light source image can be erased while ensuring sufficient luminance. As a result, it is possible to reduce the plurality of optical sheets that have been conventionally required, and as a result, the manufacturing cost is reduced.

  In this case, the diffusion plate includes a base material and a diffusion layer provided on the surface of the base material on the display panel side, and the fluorescent layer is visible in the base material or the diffusion layer. If the phosphor for converting to light is dispersed, a diffusion plate having a phosphor layer can be easily manufactured. Further, the diffusion plate is configured to include a base material, a diffusion layer provided on the display panel side surface of the base material, and a fluorescent layer provided on the light source side surface of the base material. For example, since the ultraviolet ray irradiation to the base material and the diffusion layer is blocked by the fluorescent layer, the quality is not deteriorated due to the ultraviolet ray irradiation, and the reliability is improved.

  Furthermore, according to the configuration in which an ultraviolet cut filter is not provided in the light irradiation path from the light source to the diffuser plate, an ultraviolet cut filter such as a UV cut film usually attached to the surface of the light source such as a discharge tube. Can reduce the cost.

  Then, according to the display device including the illumination device having such a configuration, the display device in which the display in use is sufficiently ensured, and there is no unevenness, and the display device has a manufacturing cost reduced as compared with the conventional display device. Can do.

  Hereinafter, embodiments of a lighting device according to the present invention and a display device including the same will be described in detail with reference to the drawings. FIG. 1 schematically shows a main part of the structure of a display device according to an embodiment of the present invention.

  A liquid crystal display device 1 shown in FIG. 1 includes a bezel 2, a display panel 3, and a lighting device 4. The bezel 2 is a member serving as a frame of the display panel 3, and the display panel 3 is formed by bonding two glasses and sealing liquid crystal therebetween.

  The illumination device 4 includes a frame 5, a diffusion plate 6, a discharge tube 7, a reflection plate 8, a chassis 9, a side holder 10, and an inverter circuit board 11. The frame 5 has a frame shape, and is used for fixing the diffusion plate 6 to the mounting surfaces of the chassis 9 and the side holder 10.

  The discharge tube 7 is fixed to the chassis 9 with electrode unit holders 12 mounted at both ends. The reflector 8 laid under the discharge tube 7 is for reflecting the light emitted from the discharge tube 7 to the display panel 3 side. The chassis 9 and the side holder 10 are members for forming a discharge tube housing portion that houses a plurality of discharge tubes 7 in parallel. In this case, the chassis 9 is formed in a substantially box shape by sheet metal processing of a metal plate material, and constitutes a bottom portion of the discharge tube housing portion and a side wall portion on the long side. The side holder 10 is a white resin member, and similarly forms a side wall portion on the short side of the discharge tube housing portion.

  An inverter circuit board 11 that generates a high-voltage AC voltage that drives the discharge tube 7 and an inverter circuit board cover 11 a that covers the inverter circuit board 11 are provided on the rear surface of the chassis 9. A control circuit board 13 that controls the display panel 3 and a control circuit board cover 13 a that covers the control circuit board 13 are also provided on the rear surface of the chassis 9.

  Next, the diffusion plate 6 according to the present invention will be described with reference to FIG. As shown in FIG. 2A, the diffusion plate 6 includes a diffusion layer 6a facing the display panel and a base material 6b facing the light source.

  In this case, the diffusion layer 6a is provided with phosphors 6c for converting ultraviolet rays into visible light dispersed in the diffusion layer 6a. Such a diffusion layer 6a is obtained by, for example, applying a solution containing a light diffusing agent made of spherical organic polymer particles and a resin mixed with a phosphor 6c to a base material 6b made of a transparent substrate and drying it. Easy to get. The phosphor 6c uses the same amount of three kinds of phosphors that emit red light, green light, and blue light by ultraviolet rays, and are mixed to emit white light. Therefore, the diffusion plate 6 diffuses light from the light source and emits light by the phosphor 6c, so that high luminance surface light emission is achieved. As a result, the light source image can be erased while ensuring sufficient luminance even if a plurality of optical sheets that have been conventionally required are reduced.

  Further, by using such a diffuser plate 6 in the illumination device 4, the optical sheet can be reduced and the number of assembling steps can be reduced, so that the manufacturing cost can be reduced. Furthermore, since there is no problem such as deterioration of display quality due to bending due to thermal factors of the optical sheet, reliability is improved.

  In this case, the ultraviolet rays included in the light irradiated from the discharge tube 7 are used as the ultraviolet rays that excite the phosphor 6 c of the diffusion plate 6. In general, the discharge tube 7 irradiates light by exciting the phosphor provided on the inner wall of the tube with the ultraviolet light generated by the discharge to emit light, but all the ultraviolet light generated by the discharge is irradiated on the inner wall of the tube. Since the phosphor is not excited and a part is emitted outside the tube, the irradiation light contains ultraviolet rays.

  Usually, in order to prevent UV deterioration such as optical sheets due to leaked UV rays and UV emission from the liquid crystal panel to the outside, UV cut to absorb UV rays such as pasting UV cut film on the discharge tube 7 A filter is provided. In the embodiment of the present invention, since this leaked ultraviolet ray is used to excite the phosphor 6c provided on the diffusion plate 6, there is no need to attach a UV cut film to the discharge tube 7, thereby reducing the cost. It is possible.

  Moreover, in order to prevent the optical sheet 34 from sticking to the upper surface of the diffusing plate 35 described in the prior art, the surface is usually embossed to make the surface uneven. Since there is no optical sheet in the illumination device 4, it is not necessary to emboss the upper surface of the diffusion plate 6, and the cost can be reduced accordingly.

  As a modification of the configuration of the diffusion plate 6 in FIG. 2A, a configuration in which the phosphor 6c is dispersed in the substrate 6b as shown in FIG. 2B may be used. The same effect is produced. Such a substrate 6b can be easily obtained by molding a transparent resin mixed with the phosphor 6c into a plate shape. Further, as shown in FIG. 2C, a solution containing the phosphor 6c is applied to the lower surface of the base plate 6b of the diffusion plate composed of the normal diffusion layer 6a and the base member 6b, that is, the surface on the light source side, and dried. The structure provided with the fluorescent layer 6d formed by this may be used. In this case, the ultraviolet light contained in the light irradiated from the light source is converted into visible light by being used for excitation of the light emission of the phosphor 6c in the fluorescent layer 6d, so that the base material 6b and the diffusion layer 6a located thereabove are converted into visible light. Since ultraviolet rays do not reach, quality deterioration such as discoloration of these members is prevented.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in a various aspect. For example, as the light source, an ultraviolet LED or a discharge tube in which a phosphor is not provided on the inner wall of the tube may be used.

It is a disassembled perspective view which shows the outline of the display apparatus provided with the illuminating device which concerns on one Embodiment of this invention. It is the figure which showed schematic structure of the diffusion plate with which the illuminating device shown in FIG. 1 is provided. It is the figure which showed schematic structure of the display apparatus provided with the illuminating device used conventionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Bezel 3 Display panel 4 Illumination device 5 Frame 6 Diffusion plate 6a Diffusion layer 6b Base material 6c Phosphor 6d Fluorescence layer 7 Discharge tube 8 Reflection plate 9 Chassis 10 Side holder 11 Inverter circuit board 11a Inverter circuit board cover 12 Electrode holder 13 Control circuit board 13a Control circuit board cover 30 Liquid crystal display device 34 Optical sheet 34a Brightness increasing sheet 34b Lens sheet 34c Diffusion sheet 35 Diffusion plate 36 Linear light source

Claims (5)

  An illumination device, wherein only a diffusion plate having a fluorescent layer for converting ultraviolet rays into visible light is disposed in a light irradiation path between a light source and a display panel.   The diffusion plate includes a base material and a diffusion layer provided on the display panel side surface of the base material, and the fluorescent layer converts ultraviolet light into visible light in the base material or the diffusion layer. The illuminating device according to claim 1, wherein the fluorescent material is dispersed.   The diffusion plate includes a base material, a diffusion layer provided on the display panel side surface of the base material, and a fluorescent layer provided on the light source side surface of the base material. The lighting device according to claim 1.   The illumination device according to any one of claims 1 to 3, wherein an ultraviolet cut filter is not provided in a light irradiation path from the light source to the diffusion plate.   A display device comprising the illumination device according to claim 1.

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