JP2000019512A - Backlight device and liquid crystal display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backlight device and a liquid crystal display using the same in which deflection of optical sheets caused by expansion and shrinking accompanying a change in temp. in use is prevented and yet the work for housing, fixing and exchanging of a light transmission plate and optical sheets is simplified. SOLUTION: At least a light transmission plate 26, a lamp unit 29, a reflector 30, a reflective sheet 27 mounted at the rear of the light transmission plate 26, plural optical sheets 41-44 laminated on the illuminating face side of the light transmission plate 26, a casing 51 to house these components and a frame plate 58 to hold these components between the casing 51 and it are equipped. Fitting holes 52 for positioning and holding the optical sheets are formed on side walls of the casing 51. Engaging projecting parts 53 are provided at least on the optical sheet adjacent to the casing 51 among the optical sheets 41-44 and the engaging projecting parts 53 are fitted to the fitting holes 52 of the casing 51.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device and a liquid crystal display device using the same, and more particularly, to preventing bending of an optical sheet caused by expansion and contraction due to a temperature change during use. The present invention relates to a backlight device and a liquid crystal display device using the same, which can simplify the work of storing and fixing the light guide plate and the optical sheet, and simplify the work of replacing the light guide plate and the optical sheet. It is.

[0002]

2. Description of the Related Art In general, display modes of a liquid crystal display device include:
There are various types, one of which has a backlight. A liquid crystal display device of a type having a backlight is provided with a liquid crystal display panel, a backlight device disposed below the liquid crystal display panel and supplying light to the liquid crystal display device, and a liquid crystal display device disposed outside an outer peripheral portion of the liquid crystal display panel. It roughly comprises a liquid crystal drive circuit board, a lower case for housing and holding a backlight, and a shield case housing the above members and having a display window.

In the above-mentioned liquid crystal display panel, two transparent insulating substrates made of glass or the like are overlapped with a predetermined gap therebetween so that the surfaces on which a transparent electrode for display and an alignment film and the like are laminated face each other. The two substrates are bonded together by a frame-like seal material provided near the peripheral portion between the substrates, and the liquid crystal is inserted into the seal material between the two substrates from the liquid crystal sealing hole, which is a cutout provided in a part of the seal material. Is sealed, and a polarizing plate is further provided outside these two substrates.

A conventional backlight provided in a liquid crystal display device having the above-described structure guides light emitted from a light source to a direction away from the light source, and irradiates the entire liquid crystal display panel with light uniformly. A light guide plate made of a transparent acrylic plate or the like; a fluorescent tube such as a cold cathode fluorescent tube arranged in parallel with the end surface along at least one end surface (one side surface) of the light guide plate; A lamp reflecting sheet that covers substantially the entire length and has a substantially U-shaped cross-section and an inner surface of which is a reflecting surface, and is disposed on the light guide plate, and emits light of a backlight emitted at a wide angle within a certain angle range. Alignment, an optical sheet such as a prism sheet for improving the brightness of the backlight, a diffusion sheet for diffusing light from the light guide plate, and a liquid crystal display disposed below the light guide plate and displaying light from the light guide plate. Panel users Is made consists reflecting sheet or the like to reflect. In such a conventional backlight, a diffusion sheet, an optical sheet, and the like disposed on the light guide plate are a double-sided adhesive tape provided along an edge of one side of a lower case that stores and holds the backlight. Was fixed.

However, in a conventional liquid crystal display device provided with a backlight having the above-described configuration, the optical sheet expands due to the heat generated by the cold cathode fluorescent tube during use, and the temperature is reduced by turning off the cold cathode fluorescent tube. The optical sheet shrinks due to the change, and the optical sheet bends due to expansion and shrinkage caused by such a temperature change, thereby causing display unevenness.
In addition, the bending of the optical sheet due to the heat generation of the fluorescent tube as described above, even after the cold cathode fluorescent tube is turned off, the optical sheet is a case from the front side, a light guide plate or a reflection sheet from the back side. Because it is sandwiched, it lasts. Therefore, prevention of the bending of the optical sheet is one of the important issues in the quality of the liquid crystal display device.

In order to solve such a problem, a backlight device disclosed in Japanese Patent Application Laid-Open No. Hei 9-127895 has been proposed. FIG. 3 is an exploded perspective view showing the backlight device. The backlight device includes a light guide plate 6, a lamp unit 9 disposed on one long side end surface of the light guide plate 6 and having a cold cathode discharge tube serving as a light source, and covering the cold cathode discharge tube. A reflector 10 for making light incident on the light guide plate 6, a reflection sheet 7 mounted on the back side of the light guide plate 6 to reflect the incident light, and a light guide plate 6 mounted on the illumination surface side of the light guide plate 6 to diffuse or condense the incident light. The four optical sheets 31, 32, 33, and 34, the housing 20 that holds and accommodates these components, and the housing 20 is fitted or screwed to the housing 20. Body 2
The frame is roughly constituted by a frame plate 28 which holds the above-mentioned constituent members between the above-mentioned components.

[0007] The four optical sheets mounted on the illuminating surface side of the light guide plate 6 are connected to the first optical sheet 3 from the light guide plate 6 side.
1, a second optical sheet 32, a third optical sheet 33, and a fourth optical sheet 34 are laminated in this order. In these four optical sheets, the adhesive 11 is applied to only one short side end of the light guide plate 6 and the first optical sheet 31 along the short side, and the first optical sheet 31 is removed. The adhesive is applied to the light guide plate 6 and the adhesive 11 is applied to only the other short side end of the second optical sheet 32 along the short side. It is fixed by sticking to the optical sheet 31. Furthermore, only one end of the third optical sheet 33 has an adhesive 11 along this short side.
Is applied, the third optical sheet 33 is attached to the second optical sheet 32, and the adhesive 11 is applied only along the other short side end of the fourth optical sheet 34 along this short side. Is applied, and the fourth optical sheet 34 is changed to a third optical sheet 33.
It is fixed by sticking it to

However, in the conventional backlight device having such a configuration, each of the optical sheets is made of the adhesive 1.
1, the optical sheet is fixed to the adjacent optical sheet or the light guide plate 6, so that the operation of fixing the optical sheet is complicated and very troublesome. For this reason, in the conventional backlight device having the above-described configuration, storing and fixing the optical sheet are complicated. Also, when performing maintenance, when replacing the light guide plate or the optical sheet, the work of peeling the light guide plate or the optical sheet is very troublesome, and when performing these peeling work,
An optical sheet that does not need to be replaced may be damaged. For this reason, when exchanging the light guide plate or the optical sheet, the peeling operation must be carefully performed, and there is a problem that the time required for the maintenance is lengthened and the maintenance cost is increased.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been described in connection with expansion due to temperature change during use.
It can prevent bending of the optical sheet caused by shrinkage,
Further, it is possible to provide a backlight device and a liquid crystal display device using the same, which can simplify the work of storing and fixing the light guide plate and the optical sheet, and simplify the work of replacing the light guide plate and the optical sheet. is there.

[0010]

According to the present invention, there is provided a light guide plate which reflects incident light and serves as a surface light source, a lamp unit which is disposed on one end face of the light guide plate and has a light source, and which covers the light source. A reflector that causes light to enter the light guide plate; a reflection sheet that is mounted on the back side of the light guide plate and reflects the incident light; and a reflector that is stacked on the illumination surface side of the light guide plate and diffuses or condenses the incident light. Sheet or two or more optical sheets, a housing for accommodating these constituent members, and fitted to the housing, or attached to the housing by a fixing member, and At least a frame plate for holding a component member is provided, a fitting hole for positioning and holding the optical sheet is formed in a side wall of the housing, and at least one of the optical sheets adjacent to the housing is formed of an optical member. Fitting convex portion provided over preparative, a backlight apparatus characterized by fitting convex portion is fitted into the fitting hole of the housing and the means for solving the above-described problem.

In the backlight device having the above structure, a clearance for preventing bending of the optical sheet is provided between the outer edge of the portion of the optical sheet where the fitting projection is not formed and the housing. Preferably, it is provided.
In addition, according to the present invention, a liquid crystal display device provided with the backlight device having the above configuration is provided as means for solving the above problem.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. FIG. 1 is an exploded perspective view showing a first embodiment of a backlight device according to the present invention. The backlight device according to the first embodiment includes a light guide plate 26 that multiple-reflects incident light and serves as a surface light source, and a lamp that is disposed on one end surface of the light guide plate 26 and has a cold cathode discharge tube as a light source. A unit 29, a reflector 30 covering the cold-cathode discharge tubes and making light incident on the light guide plate 26, and a reflection sheet 27 mounted on the back side of the light guide plate 26 and reflecting incident light
And a plurality of (four in the drawing) optical sheets 4 stacked on the illumination surface side of the light guide plate 26 and diffusing or condensing incident light.
1, 42, 43, 44, a housing 51 for accommodating these constituent members, and fitted to the housing 51 or the housing 51
And a frame plate 58 which is attached to the housing 51 by a fixing member and holds the above-mentioned constituent members between itself and the housing 51.

The lamp unit 29 is obtained by assembling the cold cathode discharge tube with a cable and a connector. Case 51
Is a rectangular frame with a bottom, and a side hole (fitting hole) for positioning and holding the optical sheet is provided on the opposing side wall.
52 are formed. In this embodiment, a lateral hole 52 is formed substantially at the center of each side wall of the housing 51. Also,
At the edge of the fourth optical sheet 44 adjacent to the housing 51 of the optical sheets 41 to 44, a projection (fitting projection) 53 corresponding to the lateral hole 52 of the housing 51 is formed. In this embodiment, a projection 53 projecting outward is formed substantially at the center of each side of the fourth optical sheet 44.

The fourth optical sheet 44 is housed and held in the frame of the housing 51 by inserting the respective projecting portions 53 into the corresponding lateral holes 52 provided therein. The optical sheets 41, 42, 43 are provided on the surface of the fourth optical sheet 44 on the light guide plate 26 side.
From the side, a third optical sheet 43, a second optical sheet 42,
The first optical sheets 41 are stacked in this order. Further, a sufficient clearance is provided between the outer edge 54 of the portion of the fourth optical sheet 44 where the protrusion 53 is not formed and the side wall of the housing 51 to prevent the optical sheet from bending. . In the first embodiment, the first to third optical sheets 41 to 43 are not provided with the projections 53 to be inserted into the lateral holes 52, but the first to third optical sheets 41 to 43 are not provided. A sufficient clearance is provided between each outer edge 55 of 43 and the side wall of the housing 51 to prevent bending of the optical sheet.

In the backlight device of the first embodiment, a lateral hole 52 for positioning and holding the optical sheet is formed in the side wall of the housing 51, and the fourth optical sheet 44 adjacent to the housing 51 is formed. Is provided in the lateral hole 52 of the housing 51, so that the fourth optical sheet 44 is held by the housing 51 without using a double-sided tape or an adhesive. The clearance between the outer edge 54 of the portion of the fourth optical sheet 44 where the projection 53 is not formed and the side wall that is the frame of the housing 51 can be sufficiently ensured. -Clearance between the outer edge 55 of the portion of the third optical sheet 41-43 where the protrusion 53 is not formed and the side wall that is the frame of the housing 51 can be sufficiently ensured, and therefore, when the backlight device is used. As the temperature changes Housing 5 even when Manabu sheet is inflated
Since it does not interfere with the side wall of the first optical device, it is possible to prevent the optical sheet from bending when the backlight device is used. Therefore, according to the liquid crystal display device provided with such a backlight device, display unevenness due to the bending of the optical sheet due to a temperature change can be prevented, and good display can be obtained.

In the backlight device according to the first embodiment, the projection 53 of the optical sheet 44 is inserted into the lateral hole 52 of the housing 51 so that the fourth optical sheet 44 is sufficiently attached to the housing 51. Since the backlight is held, it is possible to prevent display unevenness due to falling off of the optical sheet when a physical impact is applied to the backlight device and a device such as a liquid crystal display device using the same. Further, in the backlight device of the first embodiment, the lateral hole 52 is formed in the side wall of the housing 51, and the projection 53 is provided on the fourth optical sheet 44. Since the sheet 44 can be held,
There is no need to attach an optical sheet to the light guide plate using a double-sided tape or an adhesive, or to attach an adjacent optical sheet, simplifying the work of storing and fixing the light guide plate and optical sheet. is there.

Further, since the optical sheets 41 to 44 mounted on the backlight device are not fixed by a double-sided tape or an adhesive, when replacing the light guide plate or the optical sheet at the time of maintenance or the like, There is no need to remove the light guide plate or the optical sheet, and the fourth optical sheet 44 can be easily removed from the housing 51 by pulling out the projection 53 from the lateral hole 52.
Since the optical sheets 41 to 43 are merely sandwiched between the light guide plate 26 and the fourth optical sheet 44, the housing 51
By separating the frame and the frame 58, the light guide plate and the optical sheet can be easily removed, thereby simplifying the work of replacing the light guide plate and the optical sheet. Further, in the backlight device of the first embodiment, the lateral hole 52 is formed in the side wall of the housing 51, and the projection 53 of the optical sheet is inserted into the lateral hole 52, so that the backlight device can be used. In order to obtain such an effect, it is possible to prevent the optical sheet from being bent when the optical sheet is applied and to prevent the optical sheet from falling off when a physical impact is applied to a device such as a backlight device and a liquid crystal display device using the same. In addition, the size of the backlight device does not need to be increased, and the size can be reduced.

FIG. 2 is an exploded perspective view showing a second embodiment of the backlight device of the present invention. The difference between the backlight device of the second embodiment and the backlight device of the first embodiment shown in FIG. 1 is not only the fourth optical sheet 44 but also the first to third optical sheets 41. ~ 43
A projection (fitting projection) 53 corresponding to the lateral hole (fitting hole) 52 of the housing 51 is also provided at the edge of the housing 51.
The fourth optical sheets 41 to 44 are housed and held in the frame of the housing 51 by inserting the respective projecting portions 53 into the corresponding lateral holes 52 provided therein. In the second embodiment, the protrusions 5 projecting outward at substantially the center of each side of the first to third optical sheets 41 to 43 are provided.
3 are provided. In the second embodiment, the housing 51
The size of the fitting hole 52 provided in the
(The projection 53 of the first optical sheet 41, the projection 53 of the second optical sheet 42, the projection 53 of the third optical sheet 43, and the projection 53 of the fourth optical sheet 44) are inserted. It is a size that can be.

In the backlight device of the second embodiment, a lateral hole 52 for positioning and holding the optical sheets 41 to 44 is formed on the side wall of the housing 51, and the first to fourth optical sheets 41 are formed. Each of the projections 53 provided on the first to fourth optical sheets 41 to 44 is inserted into the horizontal hole 52 of the housing 51, so that a double-sided tape or an adhesive is provided. Without using etc.
The first to fourth optical sheets 41 to 44 are held by the housing 51, and the outer edges 54 and 55 of the portions of the first to fourth optical sheets 41 to 44 where the projection 53 is not formed are formed. Clearance between the side wall, which is the frame of the housing 51, can be sufficiently ensured. Therefore, even when the optical sheet expands due to a temperature change during use of the backlight device, the optical sheet does not interfere with the side wall of the housing 51. The bending of the optical sheet when the light device is used can be prevented. Therefore, according to the liquid crystal display device provided with such a backlight device, it is possible to prevent display unevenness caused by bending of the optical sheet due to a temperature change,
Good display is obtained.

In the backlight device of the second embodiment, the first to fourth optical sheets 41 are inserted by inserting the projections 53 of the optical sheets 41 to 44 into the lateral holes 52 of the housing 51. 44 to 44 are sufficiently held in the housing 51, so that when a physical impact is applied to the backlight device and a device such as a liquid crystal display device using the same, an effect of preventing display unevenness due to falling off of the optical sheet is obtained. Excellent. Further, in the backlight device of the second embodiment, a lateral hole 52 is formed in the side wall of the housing 51, and the first to fourth optical sheets 41 are formed.
Since the first to fourth optical sheets 41 to 44 can be held only by providing the projections 53 to 44 to 44, the optical sheets are attached to the light guide plate using a double-sided tape or an adhesive. Also, it is not necessary to attach adjacent optical sheets, and the work of storing and fixing the light guide plate and the optical sheet can be simplified.

Further, since the optical sheets 41 to 44 mounted on the backlight device are not fixed with a double-sided tape or an adhesive, when replacing the light guide plate or the optical sheet at the time of maintenance, etc. There is no need to remove the light guide plate or the optical sheet, and the optical sheet 41 is not required.
44 can be easily removed from the housing 51 by pulling out the projection 53 from the lateral hole 52, and thus the operation of replacing the light guide plate and the optical sheet can be simplified. Further, in the backlight device of the second embodiment, the lateral hole 52 is formed in the side wall of the housing 51, and the projection 53 of the optical sheet is inserted into the lateral hole 52. In order to obtain such an effect, it is possible to prevent the optical sheet from being bent when the optical sheet is applied and to prevent the optical sheet from falling off when a physical impact is applied to a device such as a backlight device and a liquid crystal display device using the same. In addition, the size of the backlight device does not need to be increased, and the size can be reduced.

[0022]

As described above, according to the backlight device of the present invention, the above structure prevents the optical sheet from being bent due to expansion and contraction due to a temperature change during use. The operation of storing and fixing the light guide plate and the optical sheet can be simplified, and the work of replacing the light guide plate and the optical sheet can be simplified. Further, according to the liquid crystal display device of the present invention, since the backlight device of the present invention having the above-described configuration is provided, it is possible to prevent display unevenness caused by bending of the optical sheet due to a temperature change. And good display can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of a backlight device of the present invention.

FIG. 2 is an exploded perspective view showing a second embodiment of the backlight device of the present invention.

FIG. 3 is an exploded perspective view showing an example of a conventional backlight device.

[Explanation of symbols]

26 ... light guide plate, 27 ... reflective sheet, 29 ...
Lamp unit, 30 reflector, 41 first optical sheet, 42 second optical sheet, 43
..Third optical sheet, 44... Fourth optical sheet,
51 ... housing, 52 ... side hole (fitting hole), 53 ...
-Projection (fitting projection), 54 ... outer edge, 55 ... outer edge, 58 ... frame plate.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/00 349 G09F 9/00 349E F-term (Reference) 2H042 BA20 2H089 HA40 QA06 QA09 TA11 TA17 TA18 2H091 FA14Z FA23Z FA31Z FA41Z FD01 FD06 FD11 FD13 LA04 LA09 5G435 AA08 AA12 AA17 AA19 BB12 BB15 EE03 EE04 EE05 EE07 EE27 FF03 FF08 GG24

Claims (3)

[Claims] A light guide plate that reflects incident light and serves as a surface light source;
A lamp unit having a light source, disposed on any end face of the light guide plate, a reflector that covers the light source and makes light incident on the light guide plate, and is mounted on the back side of the light guide plate and reflects incident light A reflecting sheet, one or two or more optical sheets stacked on the illumination surface side of the light guide plate for diffusing or condensing incident light, a housing for accommodating these components, and fitting to the housing Or at least a frame plate that is attached to the housing by a fixing member and holds the component member between the housing and the housing is provided. A fitting hole for holding is formed, a fitting protrusion is provided on at least an optical sheet of the optical sheet adjacent to the housing, and the fitting protrusion fits into a fitting hole of the housing. Be done And a backlight device. 2. A clearance for preventing bending of the optical sheet is provided between an outer edge of a portion of the optical sheet where the fitting protrusion is not formed and the housing. The backlight device according to claim 1. 3. A liquid crystal display device comprising the backlight device according to claim 1.