JP2001174812A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compact liquid crystal display device in which the maximum illumination area can be obtained and the area can be illuminated with uniform luminance. SOLUTION: The liquid crystal display device has an edge-type back light having a light source 4 disposed on the side face of a light guide plate 2. A light-shielding resin 3 with controlled transmitting property for the light source 4 is molded in the edge part 2b of the light guide plate by multicolor forming with two or three colors or by insert molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device used for a liquid crystal display unit for car navigation, for example, for irradiating a liquid crystal display unit with a light source.

[0002]

2. Description of the Related Art In recent years, thin and lightweight liquid crystal display devices have been widely used in display units of car navigation systems, personal computers, and all other electric appliances, and the demand for such devices has been increasing.

In this type of liquid crystal display device, it is necessary to irradiate light from a light source in order to cause a liquid crystal display section (liquid crystal cell) to emit light, and there are a reflected light method and a transmission method as a light irradiation method. The reflected light method is used in small liquid crystal displays such as calculators and wristwatches, and is reflected in the direction of the liquid crystal cell by a reflector provided on the back of the liquid crystal cell using natural light or indoor illumination light incident from the outside of the liquid crystal cell. The transmission method is used for large liquid crystal cells, and a backlight unit composed of a fluorescent lamp or the like is provided on the back of the liquid crystal cell. This is a method of irradiating light toward the back of the camera.

Most of the relatively large liquid crystal displays, such as car navigation systems and personal computers, employ a transmission system. However, the performance of the liquid crystal display largely depends on the specifications of the liquid crystal display device using a backlight unit. ing.

The backlight unit includes a light guide plate type backlight using a light guide plate 21 as shown in FIG. 5, and a direct type backlight as shown in FIG. The light guide plate type backlight uses the light guide plate 21 to irradiate the liquid crystal cell 26 with light. Among them, the uniformity of the brightness of the illuminated light is relatively good, and the light source is difficult to use. Because of the difficulty in transferring the heat to the liquid crystal cell 26, a method of arranging a light source 22 called an edge type backlight as shown in FIG.

[0006] The edge type backlight is composed of a light guide plate 21.
A reflection sheet 24 having a diffuse reflection characteristic is laid on the lower surface of the light guide plate 21. When light emitted from the light source 22 and light reflected by the lamp reflector 23 enter from the end face of the light guide plate 21, the light is reflected by the reflection sheet 24. Light diffuses in the light guide plate 21 and passes through a diffusion sheet 25 having a light diffusion layer whose surface is processed by graining or the like, and emits light whose luminance is made uniform to the liquid crystal cell 26. .

The light guide plate 21 is positioned as a main component that determines the specifications of the light guide plate type backlight along with the light source 22 which is a light emitter, and most of its products are made of PMMA resin (polymethyl methacrylate) at the time of molding. ) Is formed by injection molding.

The direct-type backlight unit reflects light emitted from the light source 26 by a light guide 27 formed in a unique shape, and provides a light-shielding pattern 28 formed so as to shield the light. The diffusion plate 29 is made uniform so as to irradiate the light with uniformity so as to block part of the directly irradiated light, and the light is further diffused by the diffusion plate 29 to emit light toward the liquid crystal cell 26.

[0009]

However, according to the above-mentioned edge type backlight unit, the light source 22 and the lamp reflector 23 for irradiating the light guide plate 21 with light are used.
Is provided on the side of the light guide plate 21, and the light guide plate 2 is provided inside the unit.
1 together with these components.

In particular, when the unit is constructed, the casing 20 is projected in a frame shape on the light emitting surface side so that the projecting portion 2 is formed.
0a is formed, and the protrusions 20a are for preventing the uniformity of the portion from being impaired by the bright line from the light source 22.

Therefore, the light guide plate 21 is provided inside the casing 20.
, A certain space other than the space for accommodating the light emitting device is required, and therefore, there is a limit in the bright line region X that emits light to the liquid crystal cell 26 with respect to the entire area of the framework of the casing 20,
Since the ratio of the light emitting area of the light guide plate 21 is limited by the protrusion 20 of the casing 20, the light emitting area is narrowed accordingly.

In the direct type backlight, since the light reflected by the light guide 27 is radiated to the diffusion plate 29, the entire unit becomes thicker or the light guide 2 becomes thicker.
However, the processing accuracy and the cost increase during the molding of the mold 7 become a problem. In particular, the light-shielding pattern 28 and the diffusion plate 29 are heated by irradiating the light directly from the light source 26 and the diffusion plate 29 is heated.
Because it affects the light emitted from the light source, it is difficult to emit light with uniform brightness, and there has been a problem that it takes time and effort to perform processing for making the brightness uniform.

The present invention has been developed to solve the above-mentioned conventional problems.
An object of the present invention is to provide a compact liquid crystal display device which can obtain a maximum light irradiation area and can irradiate with a uniform luminance.

[0014]

In order to achieve the above object, the present invention relates to an edge-type backlight liquid crystal display device having a light source disposed on a side surface of a light guide plate, wherein a light source is provided at an edge of the light guide plate. Two-color molding of light-shielding resin with transparency adjusted for three colors
The molding is performed integrally by means of multicolor molding such as four colors or insert molding.

In the liquid crystal display device described above, the extended piece at the edge of the light guide plate and the stepped surface of the light-shielding resin are integrally fixed.

The liquid crystal display device of the present invention is a liquid crystal display device of a direct type backlight, in which a light-shielding resin whose transmittance is adjusted is provided immediately above a light source emitting light from a position below a light guide plate. It is molded integrally by means such as color molding, multicolor molding such as three-color or four-color, or insert molding, and a texture pattern is provided on the back surface of the light guide plate of this liquid crystal display device so that light can be uniformly emitted from the light source. ing.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the backlight of the liquid crystal display device according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a first embodiment of the present invention and shows an edge type backlight unit. The backlight of the present invention is configured to constitute a liquid crystal display device (not shown) including the liquid crystal display unit 9 in combination with driving elements such as an electrode plate glass, a color filter, a spacer, and a change film.

In the figure, 2 is a light guide plate, 3 is PMMA,
A light-shielding resin made of a resin such as polycarbonate or acrylic, 4 is a fluorescent tube (light source), 5 is a reflector, 6 is a reflection sheet, and each component is a projection 7a of a case 7 provided on the liquid crystal display unit 9 side. Is stored and held in the case 7,
An edge-type backlight liquid crystal display device in which a light source 4 is disposed on a side surface of a light guide plate 2, wherein light-shielding resin 3 is formed on light guide plate 2 by two-color molding, three-color molding, or four-color molding. It is integrally molded by multicolor molding or insert molding. The light-shielding resin 3 is manufactured by appropriately mixing a clear resin and a white resin having a reflection characteristic so as to control an appropriate amount of light leakage and a light-shielding property.

Each fluorescent tube 4 is disposed in a U-shape or an L-shape along both left and right or upper and lower ends in a case 7 so that light can be emitted in a predetermined direction by a power source (not shown). I have. It is desirable to use a cold cathode tube lamp as the fluorescent tube 4, but it is also possible to use an appropriate lamp such as a hot cathode tube lamp.

A reflection sheet 6 is laid on the bottom surface of the case 7, and the reflection sheet 6 is deposited using a metal such as silver having a high light reflectance as a material, or formed into a sheet shape and adhered. For example, it is provided integrally with the case 7 by such means. The reflector 5 having a substantially arc-shaped cross section is arranged to be slightly longer than the fluorescent tube 4 at both end portions of the case 7 so as to extend from the reflecting sheet 6 so that light from the fluorescent tube 4 can be reflected. At the end face 2 a of the light guide plate 2 together with the light emitted from the fluorescent tube 4 to enter the light.

The light guide plate 2 is made of a light transmitting material that transmits light.
You may shape | mold with resin, such as polycarbonate.
A diffusion sheet 8 is stuck on the light emitting surface side of the light guide plate 2 to emit light,
The diffusion sheet 8 is coated with a light-transmitting ink on the back surface, and has a light diffusion layer having a concavo-convex pattern on the front surface in a grain pattern. Light incident from the end face 2a in the light guide plate 2
After scattering over the entire inside of the light guide plate 2, the diffusion sheet 8
Then, the light is radiated from behind the liquid crystal display unit 9 after being diffused and made uniform.

The light-shielding resin 3 is formed integrally with the edge 2 b of the light guide plate 2, and the light-shielding resin 3 is formed so as to be slightly larger than the diameter of the fluorescent lamp 4. It is shaped so that the fluorescent lamp 4 can be covered on the light emitting surface side when it is attached.

In FIG. 3, a protrusion 7a formed on the upper surface of the case 7 covers about half of the light-shielding resin 3 to extend the surface light-emitting area, thereby making the effective area of the surface light emission different from that of the conventional product. The light-emitting region Y is expanded to the maximum from the enlarged portion by a small amount of light leakage. Further, in FIG. 3, the extension piece 2b at the edge of the light guide plate 2 and the stepped surface 3a of the light-shielding resin 3 improve the biting properties of both resins and adjust the light-shielding property. .

Next, FIG. 2 shows a second embodiment of the backlight unit of the liquid crystal display device according to the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. This example is a liquid crystal display device of a direct type backlight in which a backlight is disposed immediately below a unit, and a light-shielding resin 3 is integrally formed by two-color molding directly above a light source 4 disposed below a light guide plate 12. Molding. Light guide plate 12
Is provided with a concave portion directly above the light source 4, a light-blocking resin 13 is integrally provided in the concave portion, and the light from the light source 4 is uniformly applied to the liquid crystal display unit (not shown). This light-shielding resin 1
Numeral 3 denotes a light-shielding resin whose transmittance is adjusted, which is adjusted in the same manner as in the above-described example, and which is provided so as to slightly increase the amount of transmitted light toward both ends. Is composed. That is, the light-shielding resin 13 is formed to be thinner in order from the thickness at the center of the cross section along both ends so that the luminance becomes uniform.

The reflection sheet 16 is provided so as to cover the periphery of the light guide plate 12, and a texture pattern 16a is provided on the back surface of the light guide plate 12 so as to uniformly irradiate light.

Next, the operation of the present invention will be described. In the liquid crystal display device of the edge type backlight of the present invention, the light-shielding resin 3 is integrally formed on the edge 2b of the light guide plate 2 by two-color molding, multicolor molding, or insert molding. The emitted light is made to enter from the end 2a of the light guide plate 2, and the brightness of the light-shielding resin 3 is also made uniform by an appropriate bright line from the light-shielding resin 3, so that the light emitting region Y is expanded accordingly. Can be.

As described above, when light is irradiated from the fluorescent tube 4 toward the light guide plate 2 and the light-shielding resin 3, the mixing of the light-shielding resin 3 and the extension 2 b of the light guide plate 2 and the light-shielding resin 3 Since the light transmittance is adjusted by the stepped surface 3a, the entire light emitting region can emit light with the same luminance.

According to the backlight of the second embodiment of the present invention, the light-shielding resin 13 is integrally provided with the light guide plate 12 by two-color molding or insert molding immediately above the light source 4 which emits light from below. Therefore, the main body can be made thin, and the brightness of the light from the light guide plate 12 can be easily made uniform by adjusting the shape of the light-shielding resin 13. Furthermore, since the production is easy, the cost can be suppressed. The light heat from the light source 4 is absorbed by the light-shielding resin 13 and the light guide plate 12, and the influence of the heat is suppressed without heating the liquid crystal cell side.

[0029]

As is clear from the above, according to the liquid crystal display device of the edge type backlight of the present invention, the maximum light emitting area can be obtained, and the display surface of the liquid crystal display device can be efficiently obtained. be able to.

Further, it is possible to provide a liquid crystal display device which can emit light with uniform brightness as a whole.

According to the direct backlight type liquid crystal display device of the present invention, the device can be made thin and compact, and the whole can be irradiated with uniform luminance. .

Further, since the above-described liquid crystal display device of the direct type backlight is provided with the grain pattern 16a, the entire light emitting surface can emit light more evenly.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a front view showing a second embodiment of the liquid crystal display device according to the present invention.

FIG. 3 is an enlarged sectional view taken along line AA.

FIG. 4 is an enlarged sectional view taken along line BB.

FIG. 5 is a reference sectional view showing a conventional edge type backlight unit.

FIG. 6 is a reference sectional view showing a conventional direct type backlight unit.

[Explanation of symbols]

 2, 12 light guide plate 2b extension piece 3, 13 light-shielding resin 3a stepped surface surface 4 light source 16a grain pattern

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/00 324 G09F 9/00 336J 336 336G F21Y 103: 00 // F21Y 103: 00 G02F 1/1335 530 F term (for reference) 2H038 AA55 BA06 2H091 FA02Y FA16Z FA23Z FA32Z FA34Z FA42Z FB02 FB08 FC02 FC12 FC18 FD15 FD22 LA18 MA03 5G435 AA02 AA03 AA18 BB12 BB15 DD09 DD13 EE26 EE27 FF26 GG13 GG08

Claims (4)

[Claims] 1. A liquid crystal display device of an edge type backlight in which a light source is disposed on a side surface of a light guide plate, wherein a light-shielding resin whose transmittance is adjusted is molded in two colors or an insert is formed on an edge of the light guide plate. A liquid crystal display device formed integrally by molding or other molding means. 2. The liquid crystal display device according to claim 1, wherein the extended piece at the edge of the light guide plate and the stepped surface of the light-shielding resin are integrally fixed. 3. A liquid crystal display device of a direct type backlight, wherein two-color molding, insert molding or light-shielding resin whose transmittance of the light source is adjusted is provided immediately above a light source that emits light from a position below the light guide plate. A liquid crystal display device which is integrally formed by other forming means. 4. The liquid crystal display device according to claim 3, wherein a grain pattern is provided on a back surface of the light guide plate so as to emit light uniformly from a light source.