JP2002091330A - Flat display device having backlight - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat display device having a backlight of an edge light system in which defective heat conduction caused by heat radiation from a fluorescence light and the increase of thickness can be avoided. SOLUTION: A lamp reflector which covers a plurality of fluorescent lamps 2 is unitedly formed by the extension part 11 of a rear bezel 1 or a metal sheet for heat radiation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display device having a backlight (a surface light source device disposed on the back side of a display panel), and more particularly to a transmission type liquid crystal display device.

[0002]

2. Description of the Related Art A flat display device such as a liquid crystal display device has been used as an image display device for a television, various computers, a car navigation system, etc. by taking advantage of features such as thinness, light weight, and low power consumption. Have been.

For example, a light transmission type liquid crystal display device includes a liquid crystal panel having a liquid crystal layer held between a pair of transparent substrates,
A surface light source device disposed on the back surface of the liquid crystal panel (surface opposite to the image display surface) to guide light source light to the liquid crystal panel;

[0004] The surface light source device is roughly classified into a direct type in which a plurality of tubular light sources such as fluorescent lamps are arranged immediately below a display panel (back side), and a tubular light source arranged on an end face of a light guide plate. There is a side light type (edge light type) in which light is emitted from the upper surface (main surface) of the light guide plate.

[0005] In order to further reduce the thickness and size of the flat display device, it is necessary to reduce the thickness of the surface light source device.
Side light type (edge light type) is the mainstream.

In a reflection type liquid crystal display device,
A side light type surface light source device which is disposed on the display surface side of a display panel (front light) is used.

As disclosed in Japanese Utility Model Laid-Open Publication No. 63-24529, an edge-light type backlight is composed of a tubular light source and a thin plate made of an acrylic resin or the like having a milky white scattering pattern printed on the back side. One end face of the light guide plate is disposed close to the tubular light source including the light plate.
Then, the light source light from the tubular light source propagates through the light guide plate,
The light is scattered by the scattering pattern on the back surface of the light guide plate and is emitted from the main surface of the light guide plate on the liquid crystal panel side.

An edge-light type backlight is also used in a stationary liquid crystal monitor. In particular, in a large-sized liquid crystal monitor, a plurality of fluorescent lamps (one side of one side of a flat display device) are provided in accordance with a demand for higher luminance. Tubular light sources) are arranged one above the other.

However, when a large amount of current is applied to the fluorescent lamp in order to achieve high luminance, the temperature of the fluorescent lamp and members around the fluorescent lamp will be too high. If the temperature of the fluorescent lamp is too high, the luminous efficiency of the fluorescent lamp will decrease. Further, when the temperature of the liquid crystal panel locally rises, display unevenness may occur.

Therefore, as shown in FIG.
The heat dissipating metal plate 62 is arranged on the lower surface of the light guide plate 25 at a point along the line. More specifically, the heat-dissipating metal plate 62 is provided on the lower surface side of the reflection sheet 26 covering the back surface of the light guide plate 25.
Is arranged. Further, a metal lamp reflector 61 having a substantially U-shaped cross section, which covers the vertically arranged lamps 2 from above, outside and below, is disposed.
1 inner end portion 61d of the lamp lower horizontal plate 61a
Is brought into contact with the metal plate 62 for heat radiation from below. Thus, the heat of the fluorescent lamp 2 is released from the heat-dissipating metal plate 62 to the outside air via the lamp reflector 61 and the end of the light guide plate 25.

On the other hand, as shown in FIG. 4, in a liquid crystal monitor having a rear metal cover called a rear bezel 1 as a measure against electromagnetic wave noise, a lamp reflector 61 is provided.
The lower horizontal plate 61a of the lamp directly contacts the rear bezel 1, and heat is radiated from the lamp reflector 61 and the end of the light guide plate 25 to the rear bezel 1.

[0012]

However, in the case of the above-mentioned conventional flat display device, the lamp reflector 61 is required.
And the heat dissipating metal plate 62 or the rear bezel 1 are superimposed on each other and heat is dissipated by heat conduction therebetween. If the contact area and contact pressure are not sufficient, sufficient heat conduction may not be achieved. Was. In addition, the thickness of the flat display device is increased by the amount of the overlap.

Furthermore, when the amount of heat generated from the fluorescent lamp 2 is large, uneven brightness may occur due to local reflection of the reflection sheet 26 and undulation.

In a flat panel display having a rear bezel, when replacing the fluorescent lamp, it is necessary to remove not only the rear bezel but also the lamp reflector.

The present invention has been made in view of the above problems, and in a flat display device provided with an edge light type backlight, poor heat radiation due to poor heat conduction between members and luminance due to undulation of a reflective sheet. An object of the present invention is to provide a flat panel display device capable of preventing occurrence of unevenness.
Another object of the present invention is to provide a flat display device that can achieve a reduction in thickness.

[0016]

According to a first aspect of the present invention, there is provided a flat panel display device comprising: a tubular light source; and a light source which is disposed with a side end face close to the tubular light source and which is incident from the side end face. A light guide plate that propagates from the upper surface while propagating, a light transmission type display panel mounted on the light guide plate, a reflecting mirror arranged to cover the tubular light source from the outside, and a lower surface of the light guide plate. Reflecting means arranged, in proximity to the tubular light source,
A flat panel display device comprising: a metal plate disposed along a lower surface of the light guide plate; wherein the metal plate extends so as to cover the tubular light source and also serves as the reflecting mirror.

According to the above configuration, it is possible to prevent poor heat radiation due to poor heat conduction between members and uneven brightness due to undulation of the reflection sheet. Further, it is possible to reduce the cost of members and assembly, and to achieve a reduction in thickness.

According to a second aspect of the present invention, the metal plate is a rear bezel that covers a drive circuit board disposed below the light guide plate from a lower surface side.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS.
This will be described with reference to FIG.

FIG. 1 is a partial longitudinal sectional view schematically showing a main part of a flat panel display according to an embodiment, and FIG. 2 is an overall longitudinal sectional view of the flat panel display according to the embodiment.

As shown in FIG. 1, two fluorescent lamps 2 are vertically arranged along the incident end face 25a of the light guide plate 25. That is, the fluorescent lamps 2 are arranged on the exit surface side and the back surface side of the light guide plate 25 in the vicinity area facing the incident end surface 25a of the light guide plate 25, and these fluorescent lamps 25 substantially overlap when viewed from the vertical direction. Located so.

A reflection sheet 26 is disposed so as to cover the back surface of the light guide plate 25, and the light exit surface (upper surface) of the light guide plate 25
An optical sheet 27 including one prism sheet and one diffusion sheet is arranged. And this optical sheet 27
, The liquid crystal panel 3 is placed on the emission surface of the light guide plate 25.

The light guide plate 25 and the fluorescent lamp 3 are housed and held by a frame 4 made of a resin having a frame shape. The frame 4 is formed of a light guide plate 25 other than the incident end face 25a.
Of the light guide plate 25 except for where the TCP (tape carrier package) 53 is disposed. Further, the extending portion 41 from the frame 4 covers most of the back surface of the light guide plate 25.
That is, the extending portion 41 of the frame 4 is
The light guide plate 25 is covered on the rear surface except for the location along the line and the location where the TCP side drive circuit board 51 is disposed. Although not shown, the fluorescent lamp 2 is held by the frame 4 via rubber caps or the like at the electrode portions at both ends.

From the light guide plate 25 and the emission surface side of the frame 4, the peripheral portion 3 a of the display surface of the liquid crystal panel 3 and the frame 4
Is covered with a metal front bezel 15. The front bezel 15 has a shape in which a metal plate member having an inverted L-shaped cross section is combined in a frame shape, and holds the liquid crystal panel 3 from the emission surface side and further reinforces the frame 4. , And serves to prevent leakage of electromagnetic noise to the emission surface side and the end surface side.

On the other hand, a main drive circuit board 52 of the flat panel display device is arranged on the back side of the light guide plate 25 and below the frame extending portion 41.

The main drive circuit board 52 and the TCP
The substantially tray-shaped rear bezel 1 made of a metal plate is covered from below the side drive circuit board 51 so as to cover the entire back surface of the light guide plate 25. The rear bezel 1 is provided mainly for shielding electromagnetic noise, and a portion corresponding to the bottom plate of the tray is arranged at a predetermined distance from the main drive circuit board 52 and the TCP side drive circuit board 51.
The portion of the rear bezel 1 corresponding to the side plate of the tray is superimposed on the front bezel 15 from the inside except for a portion along the incident end face 25a of the light guide plate 25 so as to contact or substantially contact the front bezel 15. Such a vertical side plate portion 12 of the rear bezel is arranged at a place where the TCP 53 is arranged so as to be at a predetermined distance from the driving IC 54 of the TCP 53.

At a position along the incident end face 25 a of the light guide plate 25, a portion corresponding to the bottom plate of the rear bezel 1 abuts on the lower surface of the light guide plate 25 via the reflection sheet 26 to form a metal plate portion 13 for heat radiation. An extending portion 11 extending from the heat-dissipating metal plate portion 13 is inserted into the frame 4 to cover a pair of the fluorescent lamps 2 from the back side, the outside, and the display surface side. Has a lamp reflector.

As described above, since the lamp reflector is formed integrally with the radiating metal plate portion 13 by the extending portion 11 of the rear bezel 1, heat from the fluorescent lamp 2 is dissipated by the extending portion 11 for the lamp reflector. Radiating metal plate part 1
3 is easily and reliably transmitted to the metal plate portion 1 for heat radiation.
3, and other components of the rear bezel 1 are smoothly radiated into the outside air. In addition, the light guide plate 2
The heat transmitted to 5 is also smoothly radiated to the outside air through the metal plate portion 13 for heat radiation.

Here, the rear bezel 1 is preferably made of aluminum or aluminum alloy having high heat conductivity and heat dissipation. In addition, a reflector for improving the reflection performance is arranged on the inner side surface of the lamp reflector extension 11. As the reflecting material, for example, a silver vapor-deposited film can be stuck and placed with an adhesive. Alternatively, a reflecting material can be arranged on the entire inner surface of the rear bezel 1 and the extending portion 11 for the lamp reflector. In this case, the reflection sheet 26 may be disposed only at a position where the rear bezel 1 is not located on the back surface of the light guide plate 25.

When the lamp reflector is integrally formed with the rear bezel 1, it can be easily manufactured by bending a metal plate, similarly to the conventional rear bezel.
Therefore, the manufacturing cost and the assembling cost of the members can be reduced by the reduced number of members by the configuration of the above embodiment, so that the manufacturing cost of the backlight can be reduced. Further, in order to replace the fluorescent lamp 2, the fluorescent lamp 2 and its lead wires can be simultaneously removed simply by removing the rear bezel 1. Further, the portion near the fluorescent lamp 2 can be made thinner than when the rear bezel and the lamp reflector are overlapped.

Further, since the reflection sheet is sufficiently reduced from being locally heated in the vicinity of the fluorescent lamp 2, the occurrence of uneven brightness due to the undulation of the reflection sheet is sufficiently prevented.

Although not shown, as a modified example, a heat-dissipating metal plate that covers the entire back surface of the light guide plate 25 is disposed separately from the rear bezel 1, and a lamp reflector is formed by the extending portion of the heat-dissipating metal plate. Can also. In this case, if the heat radiating metal plate and the inner surface of the lamp reflector extending portion are covered with the reflecting material, the reflecting sheet can be omitted, thereby further reducing the number of members.

According to the modification, the number of components and the manufacturing cost can be reduced as compared with the case where the heat-dissipating metal plate and the lamp reflector are separately arranged and overlapped at the end of the light guide plate. And the thickness of the backlight can be reduced. In addition, it is possible to sufficiently prevent the reflection sheet from undulating due to local heating of the reflection sheet, thereby causing uneven brightness.

[0034]

By reducing the number of members, the cost of members and assembly can be reduced, and the thickness can be reduced. Further, it is possible to prevent poor heat radiation due to poor heat conduction between the members and occurrence of uneven brightness due to undulation of the reflection sheet.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view schematically showing a main part of a flat panel display device according to an embodiment.

FIG. 2 is an overall vertical sectional view of a flat panel display device according to an embodiment.

FIG. 3 is a partial longitudinal sectional view corresponding to FIG. 1, schematically showing a main part of a conventional flat panel display device.

FIG. 4 is a partial longitudinal sectional view corresponding to FIG. 1, schematically showing a main part of another conventional flat panel display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rear bezel 11 Lamp reflector consisting of an extension of rear bezel 15 Front bezel 2 Fluorescent lamp 25 Light guide plate 25a Incident end face of light guide plate 26 Reflection sheet 27 Optical sheet 3 Liquid crystal panel 4 Resin frame

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/13357 G02F 1/1335 530 F-term (Reference) 2H091 FA14Z FA23Z FA42Z FB08 GA11 LA04 LA11 LA12 LA18 5G435 AA12 AA18 BB12 BB15 DD13 EE27 FF03 FF08 GG44 LL04 LL08 LL17

Claims (7)

[Claims] 1. A tubular light source, a light guide plate disposed so that a side end face is close to the tubular light source, and a light guide plate that emits light from the top face while propagating light from the tubular light source that enters from the side end face; A light-transmitting display panel mounted on the light plate; and a metal plate arranged along the lower surface of the light guide plate in proximity to the tubular light source, and an extending portion from the metal plate is A flat display device comprising a reflecting mirror that covers a tubular light source from the outside. 2. A tubular light source, a light guide plate disposed so that a side end face is close to the tubular light source, and a light guide plate which emits light from the top face while propagating light from the tubular light source incident from the side end face; A light transmissive display panel mounted on the light plate, and a metal rear bezel disposed below the light guide plate and covering the drive circuit board from the lower surface side, wherein the rear bezel corresponds to the tubular light source. A flat display, comprising: a metal plate portion disposed along the lower surface of the light guide plate at an adjacent position, and a portion extending from the metal plate portion forms a reflecting mirror that covers the tubular light source from the outside. apparatus. 3. The flat display device according to claim 2, wherein an upper surface of said metal plate portion is covered with a reflective material. 4. A plurality of tubular light sources arranged vertically one above another, and arranged with their side end faces close to these tubular light sources,
A light guide plate that emits light from the top surface while propagating light from the tubular light source incident from the side end surface; a light transmission type display panel mounted on the light guide plate; A metal heat radiating plate disposed along the lower surface of the light guide plate and dissipating heat from the tubular light source; and an extension from the heat radiating plate forms a reflecting mirror that covers the tubular light source from outside. Characteristic flat display device. 5. The flat panel display according to claim 4, wherein a reflection sheet is disposed between said heat radiation plate and said light guide plate. 6. A flat display device according to claim 4, wherein said heat radiating plate is disposed so as to cover the entire lower surface of said light guide plate. 7. The flat display device according to claim 4, wherein an upper surface of the heat sink is covered with a reflective material.