TW200900765A - Light guide panel having light mix-member for LCD back light unit and LCD back light unit thereby - Google Patents

Abstract

Disclosed herein is a light guide plate for an LCD back light unit. More specifically, provided is a light guide plate for an LCD back light unit, which employs a three-color or white LED as a light source to render white light. The light guide plate comprises a rear surface provided with geometric prisms to reflect or refract light emitted from a light source, side surfaces on which light is incident, and a front surface from which the light is emitted, the front surface connected to the side surfaces while facing the rear surface, wherein the front surface includes an optical mix-member.

Description

200900765

File: TW4186F IX. Description of the Invention: [Technical Field of the Invention] The present invention relates to a light guide plate of a backlight module of a liquid crystal display device and a backlight module of a liquid crystal display device using the same, and particularly A backlight module for a backlight module using a dichroic or white light-emitting diode as a light source to generate a white light, and a backlight module for a liquid crystal display device using the same. 0 [Prior Art] Generally, a liquid crystal display device applies an electric field to a liquid crystal layer between two glass substrates to display numbers or images. The liquid crystal layer is composed of a material having an intermediate state between the liquid and the solid. Since the liquid crystal display device is a non-self-illuminating device, it is necessary to have a backlight module as a light source to generate light. The liquid crystal system is evenly arranged in the liquid crystal panel, and in the liquid crystal panel, the light transmittance of the light generated by the backlight module is adjusted to display an image. (j', FIG. 1 and FIG. 2 are exploded views of the backlight module of the conventional liquid crystal display device. According to the position of the light source 105, the backlight module 10 of the liquid crystal display device can be divided into a direct type backlight. The module and the edge-lit backlight module. The light source 1〇5 of the direct-lit backlight module is disposed on the rear side of the liquid crystal display panel 1 , and the light source 105 of the edge-lit backlight module is disposed on the liquid crystal display panel 100 . According to the shape of the light guide plate, the edge light type backlight module can be further divided into a wedge-shaped backlight module and a flat type (flat_type) back 6 200900765

File: TW4186F optical module. FIG. 1 illustrates a flat panel backlight module in which light sources 1〇5 are disposed on both sides of the liquid crystal panel 100. FIG. 2 illustrates a wedge-shaped backlight module in which the light source 105 is disposed on one side of the liquid crystal panel 100. As shown in Figs. 1 and 2, the backlight module of the conventional liquid crystal display device includes a light source 105, a light guide plate 11 (or 112), a reflection plate 11 $, a diffusion plate 120, a cymbal 125, and a protective plate 130. Light source 105 is used to emit light. The liquid crystal display device can have different kinds of light sources. However, since the cold cathode tube (CCFL) consumes low power and emits high-intensity white light, the liquid crystal display device generally uses a cold cathode tube as the light source 105. However, due to the inclusion of cold cathode tubes, their use is limited by the ring, under the regulations. In addition, cold cathode tubes require inverters to read and control cold cathodes, increasing their cost. On the other hand, the advantages of light-emitting diodes (LEDs) include the absence of mercury. In addition, compared with the cold cathode tube, the illuminating-polar body is 卩% long. However, a drawback of the light-emitting diode is that the light emitted by the three-color light-emitting diode must be uniformly mixed to produce white light. The light guide plate 110 (or 112) is disposed under the liquid crystal panel 1 且 and located at the light source 105. The light guide plate (10) is configured to convert the point light emitted by the light source into a surface light, and project the light onto the liquid crystal panel. The light guide plate 11G shown in Fig. 1 has a uniform flat plate, and the light guide plate 112 shown in Fig. 2 has a wedge shape. The reflection plate H5 is disposed on the rear side of the light guide plate 或ι (or 112). The reflecting plate 115 is for reflecting the light emitted by the light source (8) and reflecting the light to 7 200900765

File: TW4186F The liquid crystal panel 100 above the reflection plate 115. The diffusion plate 12A is disposed on the front side of the light guide plate 110 (or II2). The diffusion plate 120 is for homogenizing the light passing through the light guide plate 110. When light passes through the diffuser 120, the light diffuses in the horizontal and vertical directions, thereby rapidly reducing its brightness. To solve this problem, a plurality of prism lenses 125 are used to refract and concentrate the light, thereby enhancing the brightness.

The protective plate 130 is disposed on the cymbal 125 to prevent the cymbal U5 from being scratched. When the two slabs 125 are arranged in the vertical and horizontal directions, respectively, the protective plate 130 prevents the Moire effect. Although not shown in Figures 1 and 2, the conventional backlight module further includes a frame (m〇ld frame/h〇using) and a back plate (back c〇ver/iamp (3) ver). The components constituting the backlight module are fixed on the frame, so that the backlight is two-stage and can be integrated into one. The backplane is used to protect and support the backlight module while maintaining the strength of the backlight module. Fig. 3 and Fig. 4 are enlarged cross-sectional views showing the light path generated by the light source 1〇5 in the flat plate guide and the counter 110.柘1 及目 and Fig. 6 are enlarged cross-sectional views showing the optical path of the light generated by the light source 105 in the wedge-shaped light guide plate 2. As shown in the figure (the liquid crystal light source 105 is generally located on one side of the backlight module 10; none of them are directly located on the rear side of the panel), so that the light edge may be wider than the other parts of the entire surface. The side of the backlight module (or the Xizhiyue 杈 group is brighter. Therefore, the light guide plate 110 gram material 2: used to prevent this phenomenon. The light guide plate - the general system is transparent, and the acryl has high strength, Lightweight and visible 8

200900765 File: TW4186F High light transmittance, not easily broken or deformed. In other words, the light guide plate 110 (or 112) causes the light emitted by the light source 105 to be uniformly projected onto the entire surface of the light guide plate 110 (or 112). However, when the backlight module 10 is disassembled and the light is emitted from the light source 105 on the side of the light guide plate 110 (or 112), the light is not uniformly projected onto the entire surface of the light guide plate 110 (or 112). It is concentrated on both ends of the light guide plate 110 (or 112). This is because the light guide plate 110 directs the light emitted from the light source 105 to be projected to the opposite side of the light guide plate 110. As shown in Figs. 4 and 6, the surface of the light guide plate 110 is specially treated so that light scattered in the light guide plate 110 is reflected so that light can be transmitted to the entire surface of the light guide plate 110. More specifically, the rear surface of the light guide plate 110 has a plurality of protrusions or recesses 113. The shape of such projections or recesses 113 is designed in consideration of the distance from the light source 105 and the like. When the surface of the light guide plate 110 has a convex portion or a concave portion 113, the planar light emitted from the entire surface of the light guide plate of the liquid crystal display device has high brightness and uniformity. When a cold cathode tube is used as a light source, since the light source itself emits white light, the brightness and uniformity of the light are major problems to be considered. However, since the cold cathode tube has the problems described above, there is still a continuing possibility to study the use of the light-emitting diode as a light source for the backlight module. When a light-emitting diode is used as the light source, the light source emits light of three colors (i.e., red light, green light, and blue light) instead of white light. The light of these three colors must be mixed to produce a white flat light. In order to produce white 9

200900765 File: TW4186F The color plane light, the light of the three colors must be mixed in the direction of the vertical light path. Accordingly, the present invention provides a light guide plate which can appropriately mix light of three colors. SUMMARY OF THE INVENTION The present invention relates to a light guide plate of a backlight module of a liquid crystal display device for mixing light of three colors emitted by a light source, thereby generating white light with high uniformity and excellent visibility. . According to the present invention, a light guide plate of a backlight module of a liquid crystal display device is provided. When a white light emitting diode is used as a point light source, the light guide plate of the present invention mixes the light emitted by the white light emitting diode, thereby generating a high uniformity. Light and excellent visibility. According to the present invention, a backlight module of a liquid crystal display device using the light guide plate of the present invention is proposed. It is to be noted that the invention is not limited by the scope of the invention, and other objects and features of the invention can be readily understood from the following description. According to the present invention, a light guide plate of a liquid crystal display device includes a rear surface, a plurality of side surfaces, and a front surface. The rear surface has geometric prisms that reflect or refract light from the source. Light is incident on the side surface and is emitted from the front surface. The front surface is attached to the side surface and opposite the rear surface. The front surface has a light mixing member. The light mixing member is preferably used to mix light in the direction of the vertical light path and includes a plurality of repeatedly arranged cylindrical mirrors. 200900765

File: TW4186F In order to make the above description of the present invention more comprehensible, a preferred embodiment will be described below in detail with reference to the accompanying drawings. The reference drawings are described in detail below. The advantages, features, and methods of achieving the invention can be seen in conjunction with the drawings and will become more apparent from the description. It is to be understood that the present invention is not limited to the embodiments of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention. The embodiments of the present invention are provided to those of ordinary skill in the art to which the invention pertains, but are not intended to limit the scope of the invention. The scope of the invention is defined by the scope of the appended claims. Similar components are represented by similar symbols. In order to clearly illustrate the invention, the dimensions of the elements of the invention are shown exaggerated in the drawings. In the following description, the phrase "a component is in another element or a component is connected to another component" means that the components may be in contact with each other, or one component is at a distance from another component. Separated. It should be noted that when such elements are separated by a distance, a description of the third element used to connect the elements may be omitted. Hereinafter, a light guide plate of a backlight module of a liquid crystal display device according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 7 is a schematic view showing a light guide plate of a backlight module of a liquid crystal display device according to a preferred embodiment of the present invention. 11 200900765

File: TW4186F M refers to FIG. 7'. This embodiment is a flat panel backlight module, and the light is incident on both sides of the backlight module. The light guide plate 300 of the backlight module of the liquid crystal display device of the present embodiment includes a plurality of side surfaces 3〇1, a front surface 3〇3, and a rear surface: 305. The light is incident on the side surface 3 (Π, and is emitted from the front surface 303. The front surface 303 is attached to the side surface 3G1. The rear surface 3〇5 is used to reflect light. The front surface 3〇3 has the light mixing member 31〇.

The light mixing member 310 includes a plurality of repeatedly arranged cylindrical mirrors (as in the lenses) 312. The configuration of the light mixing member 310 is perpendicular to the longitudinal direction of the light source. The height of the light mixing member 310 is preferably up to 10% of the overall height of the light mixing member 31. The light source 306 is disposed on the side surfaces 3 of both sides of the light guide plate 3, and the light source 306 is a three-color light emitting diode (i.e., red light, green light, and blue light) that emits light of three colors. The light mixing member 310 is for mixing light of three colors to produce white light. When a white light-emitting diode is used as the light source, the light-mixing member 31 is used to eliminate the bright spots near the light-emitting diode. A plurality of geometric prisms 320 are disposed on the rear surface 305 and are used to reflect light rays incident on the rear surface 305 and reflect the light to the front surface 303. The longitudinal direction of the crucible 122 is perpendicular to the direction in which the light source emits light. As shown in Figure 7, the prism 320 has a triangular cross section. However, the prism 320 may also be a tetrahedron, a trapezoidal concave wedge or a trapezoidal convex wedge. Light emitted by the light source 306 is incident on the side surface 301, and is reflected by the rear surface 305 and travels toward the front surface 303. When light passes through the front 12 200900765

File: TW4186F When the light absorbing member 310 of the surface 303 (i.e., the cylindrical mirror 312) is used, the light is mixed in the direction of the vertical light path. FIG. 8 is a schematic view showing a light guide plate of a backlight module of a liquid crystal display device according to another embodiment of the present invention. As described above, the embodiment of Fig. 7 is a flat type light guide plate 3(), and the light source is incident on both sides of the light guide plate 300. The embodiment of Fig. 8 is a wedge-shaped light guide plate 400' whose light source is incident on one side of the light guide plate 4''. The rear surface 405 of the wedge-shaped light guide plate 400 is inclined toward the front surface 403 (, and oblique. When the light is incident only on one side of the light-emitting plate, since the intensity of the light is reduced as the direction of the light travels, the distance light source is The longer the distance 406 is, the longer the length of the ridge on the surface 405. The 稜鏡42〇 is used to refract light. Therefore, the longer the length of the prism from the farther from the light source, the more the light intensity can be avoided. 9 is a cross-sectional view of a light-mixing member of a light guide plate of a backlight module according to an embodiment of the present invention. As shown in FIG. 9 , the light-mixing member 310 The front surface of the light guide plate 300 is formed to mix light in a horizontal direction. The light mixing member 310 includes a plurality of columnar mirrors 312. The columnar mirror 312 is used for mixing light in a horizontal direction, so that the three-color light emitting diode light source is The red, green and blue light are mixed to produce white light. When the white light emitting diode is used as the light source, the light mixing member 310 can eliminate the bright spots near the light emitting diode, thereby increasing the uniformity of the light.

200900765 File: TW4186F For the purpose of mixing light, the radius of curvature of the cylindrical mirror 312 is preferably between 1 Ομπι and 250 μηι. Too small a radius of curvature will result in insufficient light mixing. Excessive radius of curvature may expose the pattern of the cylindrical mirror. The lenticular mirrors 312 of this embodiment have the same radius of curvature and are closely adjacent to each other without a gap. However, the length of the lenticular mirror 312 may also become longer as the distance from the center of the light guide plate increases. Figure 10 is a cross-sectional view showing a light-mixing member of a light guide plate of a backlight module of a liquid crystal display device according to another embodiment of the present invention. 11 is a cross-sectional view showing a light-mixing member of a light guide plate of a backlight module of a liquid crystal display device according to still another embodiment of the present invention. As shown in FIG. 10, the light mixing member 310 includes a flat portion 315. The flat portion 315 has a predetermined width d and is located between adjacent cylindrical mirrors 314. As shown in Fig. 11, the light mixing member 310 can have two cylindrical mirrors 316 and 318 having different radii of curvature. Figure 12 is a cross-sectional view showing the optical path of a light guide plate of a backlight module of a liquid crystal display device according to another embodiment of the present invention. As shown in Fig. 12, the light emitted by the three-color light-emitting diode as a light source is refracted when passing through the light-mixing member 310 (i.e., the cylindrical mirror 312). Since the direction of refraction is perpendicular to the surface, the light toward the front surface is mixed in the direction of the vertical path. As a result, the light emitted by the three-color light-emitting diodes is mixed with each other to produce white light that travels toward the front surface. Figure 13 is a cross-sectional view showing the optical path of a light guide plate of a backlight module of a liquid crystal display device according to still another embodiment of the present invention. As shown in Fig. 13, as a white light-emitting diode of the light source 306 14 200900765

File: The light emitted by TW4186F is deflected as it passes through the light mixing member 310 (i.e., the cylindrical mirror 312). Since the direction of refraction is perpendicular to the surface, the light directed toward the front surface is mixed in the direction of the vertical optical path. As a result, the light emitted by the white light-emitting diodes is mixed with each other to produce white light that travels toward the front surface. Thereby, the bright spots generated in the vicinity of the light-emitting diodes can be eliminated, thereby producing uniform planar light rays traveling toward the front surface. When a three-color light-emitting diode is used as the light source, the light-mixing member of the light guide plate of the backlight module of the liquid crystal display device of the present invention allows the light generated by the light source to be uniformly mixed to generate white light. When a white light-emitting diode is used as the light source, the light-mixing member is used to eliminate bright spots near the white light-emitting diode, thereby generating uniform planar light. The invention provides a light guide plate of a backlight module of a liquid crystal display device, which can generate uniform white plane light when a three-color or white light-emitting diode is used as a light source. In view of the above, the present invention has been disclosed in a preferred embodiment, and is not intended to limit the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims. 15

200900765 File:TW4186F [Simple diagram of the drawing] The first and second figures illustrate an exploded view of the backlight module of the conventional liquid crystal display device; and the third to sixth figures show the light path of the light generated by the light source in the light guide plate. FIG. 7 is a schematic view showing a light guide plate of a backlight module of a liquid crystal display device according to a preferred embodiment of the present invention; FIG. 8 is a view showing a liquid crystal display device according to another embodiment of the present invention; FIG. 9 is a cross-sectional view of a light-mixing member of a light guide plate of a backlight module of a liquid crystal display device according to an embodiment of the present invention; FIG. 10 is a view showing another embodiment of the present invention; FIG. 11 is a cross-sectional view of a light-mixing member of a light guide plate of a backlight module of a liquid crystal display device according to an embodiment of the present invention, and FIG. 11 is a cross-sectional view of a light-mixing member of a light guide plate of a backlight module of a liquid crystal display device according to still another embodiment of the present invention. 12 and 13 are cross-sectional views showing optical paths in a light guide plate of a backlight module of a liquid crystal display device according to an embodiment of the present invention. [Main component symbol description] 10: Backlight module 100. Liquid crystal display panel 110, 112, 300: Light guide plate 105, 306, 406: Light source 16 200900765

File: TW4186F 113: convex portion or concave portion 115: reflection plate 120: diffusion plate 125: cymbal sheet 130: protection plate 301, 401: side surfaces 303, 403: front surface 305, 405: rear surface f 310, 410: light mixing Parts 312, 412, 314, 316, 318: cylindrical mirror 315: plane portions 320, 420: 稜鏡 17

Claims (1)

200900765 File: TW4186F X. Patent Application Range: 1. A light guide plate for a liquid crystal display device, the light guide plate comprising: a rear surface comprising a plurality of geometric ridges for reflecting or refracting light emitted by a light source; a side surface, the light is incident from the side surfaces; and a front surface, the light is emitted from the front surface, and the front surface is coupled to the side surfaces and opposite to the rear surface; wherein the front surface includes a front surface Light mixing parts. D. The light guide plate of claim 1, wherein the light-mixing member is disposed perpendicular to one of the light sources. 3. The light guide plate of claim 1 wherein the height of the light-mixing member is preferably 0.1% to 10% of the overall height of the light-mixing member. The light guide plate, wherein the light mixing member comprises a plurality of repeatedly arranged columnar mirrors. 5. The light guide plate of claim 4, wherein the I-column mirror preferably has a radius of curvature between ΙΟμπι and 250 μιη. 6. The light guide plate of claim 4, wherein the height of the lenticular mirrors increases as the distance from the center of the light guide plate increases. 7. The light guide plate of claim 4, wherein the columnar mirrors are evenly spaced from each other. 8. The light guide plate according to claim 1, wherein the light-mixing member comprises a plurality of columnar mirrors having different curvature radii 18 200900765 File: TW4186F and repeatedly arranged. 9. The light guide plate of claim 1, wherein each of the geometric ridges has a triangular, tetrahedral, trapezoidal concave wedge or trapezoidal convex wedge. The backlight module of the liquid crystal display device, comprising: a light source comprising a light emitting diode (LED); and the light guide plate according to claim 1 . A liquid crystal display device comprising the backlight module according to claim 10 of the patent application. 19