TWI414835B - Light guide plate and backlight module - Google Patents

Abstract

The present invention relates to a light guide plate and a backlight module. The light guide plate includes a top light output surface, a bottom surface opposite to the light output surface and at least one side connecting the bottom surface and the top light output surface. At lease one surface of the bottom surface and the top light output surface includes a center and a plurality of scattering dots disposed around the center to form a plurality of loops. The backlight module includes at least one light source and a light guide plate. The light guide plate is the above-described light guide plate. The light source is disposed under the light guide plate and opposite to the center of the bottom surface.

Description

Light guide plate and backlight module

The invention relates to a light guide plate and a backlight module, in particular to a light guide plate and a direct type backlight module suitable for a direct type backlight module.

In recent years, flat panel displays have developed rapidly and have been widely used in personal computers, televisions, mobile communications, and consumer electronics. At the same time, electronic products are increasingly demanding flat display devices such as liquid crystal display devices. The backlight module is an important component in the display device, and the light emitted by the point source or the line source is scattered by the light guide plate to form a light source. Therefore, designing various backlight modules has become a research hotspot.

The backlight module generally includes a light source and a light guide plate, and the light source is disposed opposite to the incident surface of the light guide plate. The light guide plate guides the direction of transmission of the light beam emitted from the light source, and converts the line source or the point source into a surface source. According to the position of the light source, the backlight module can be divided into two types: direct type and side type. The direct type backlight module refers to direct illumination of the light source directly under the light guide plate. The side-mounted backlight module generally places the light source on the side of the light guide plate, and the light is coupled into the light guide plate from the side surface to form a total reflection in the light guide plate and continuously propagate forward. By destroying the total reflection condition, the light exiting surface of the light guide plate is uniformly emitted. It can be seen that the structure of the light guide plate has an important influence on the light-emitting effect of the backlight module.

The prior art provides a light guide plate applied to a direct type backlight module, and the light guide plate includes a light incident surface, a light emitting surface opposite to the light incident surface, and a plurality of light emitting surfaces distributed on the light incident surface or/and the light emitting surface Scattering dots. The plurality of scattering dots are randomly distributed in a radial manner at the entrance surface or/and the center of the illuminating surface .

However, the light emitted by the light source is usually a cylindrical beam, and the light guide plate is square or rectangular. Since the plurality of scattering dots of the light guide plate are randomly distributed in a radial manner on the light incident surface or/and the center of the light exit surface, the uniformity of the light emitted from the edge of the light guide plate is poor, and the uniform light output of the direct type backlight module cannot be achieved.

In view of the above, it is necessary to provide a light guide plate and a direct type backlight module that can improve the uniformity of light emission of a direct type backlight module.

A light guide plate comprising: a bottom surface; a light emitting surface opposite to the bottom surface; and a side surface connecting the bottom surface and the light emitting surface; and a plurality of scattering mesh points disposed on the bottom surface or/and the light emitting surface, wherein the plurality The scattering mesh points are distributed over a plurality of rings around the bottom surface or/and the center of the light exiting surface, and the annular shape of the scattering mesh points distributed away from the center of the bottom surface or/and the center of the light exiting surface corresponds to the shape of the light guide plate.

A backlight module includes: a light guide plate, the light guide plate includes a bottom surface, a light exit surface opposite to the bottom surface, and a side surface connecting the bottom surface and the light exit surface, and a plurality of scattering mesh points are disposed on the bottom surface or/and a light-emitting surface; the light source is disposed at a position directly opposite to a center of the bottom surface directly below a bottom surface of the light guide plate; wherein the plurality of scattering mesh points are distributed around a plurality of the bottom surface or/and the center of the light-emitting surface The annular shape of the scattering mesh points on the ring shape and away from the center of the bottom surface or/and the center of the light exiting surface corresponds to the shape of the light guide plate.

Compared with the prior art, the bottom surface of the light guide plate includes a center, and a plurality of scattering mesh points are distributed in a plurality of annular shapes around the center of the bottom surface. Therefore, after the light emitted by the light source is reflected by the light guide plate, a plurality of scattering mesh points distributed in a ring shape are uniformly scattered to the light exit surface. The light guide plate can improve the uniformity of the light output of the direct type backlight module.

20‧‧‧Backlight module

200‧‧‧Light source

202‧‧‧Light guide plate

204‧‧‧reflector

206‧‧‧Microprism system

208‧‧‧Polarization conversion system

210‧‧‧scatter plate

212‧‧‧ bottom

214‧‧‧Glossy surface

216‧‧‧ side

218‧‧‧ Center

220‧‧‧scattering points

222‧‧‧Reflection Department

224‧‧‧reflective surface

226‧‧·reflective film

228‧‧‧Lighting device

230‧‧‧ concentrating device

232‧‧‧beam

234‧‧‧Excessive area

236‧‧‧last circle

238‧‧‧ first round n-ring ring

240‧‧‧ first ring

FIG. 1 is a schematic structural diagram of a backlight module according to an embodiment of the present technical solution.

FIG. 2 is a schematic diagram of a distribution of scattering dots of a light guide plate according to an embodiment of the present technical solution.

The light guide plate and the backlight module of the present technical solution will be further described in detail below with reference to the accompanying drawings.

Referring to FIG. 1 , an embodiment of the present disclosure provides a backlight module 20 including a light source 200 , a light guide plate 202 , a reflective plate 204 , a microprism system 206 , a polarization conversion system 208 , and a scattering plate 210 .

The light guide plate 202 includes a bottom surface 212 , a light emitting surface 214 opposite to the bottom surface 212 , and a side surface 216 connecting the bottom surface 212 and the light emitting surface 214 , and the bottom surface 212 includes a center 218 . The light source 200 is disposed at a position directly opposite to the center 218 of the bottom surface 212 directly below the bottom surface 212 side of the light guide plate 202. The reflector 204 is disposed between the light source 200 and the bottom surface 212 of the light guide plate 202. The microprism system 206 , the polarization conversion system 208 , and the scattering plate 210 are sequentially disposed on the light emitting surface 214 side of the light guide plate 202 .

The light source 200 includes a light emitting device 228 and a light collecting device 230. The light-emitting device 228 is a light source such as a fluorescent lamp or a light-emitting diode (LED). In this embodiment, the light-emitting device 228 is a single-color light-emitting diode, and the light-concentrating device 230 is two aspherical curved surfaces. The light emitting diode is disposed between two aspherical curved surfaces. The light beam 232 emitted by the light source 200 is incident perpendicularly to the center 218 of the bottom surface 212 of the light guide plate 202. Preferably, the light source 232 emitted by the light source 200 has a diameter of 6 to 8 mm.

The light guide plate 202 is a circular, square, rectangular or other polygonal transparent substrate. The material of the transparent substrate may be engineering plastics, polymethyl methacrylate (PMMA) or glass. The thickness of the light guide plate 202 is not limited and can be selected according to actual conditions. In this embodiment, the light guide plate 202 is a square PMMA substrate having a side length of 50 mm.

Referring to FIG. 2 , a plurality of scattering dots 220 are disposed on the bottom surface 212 of the light guide plate 202 . The scattering dots 220 are distributed over a plurality of rings around the center 218 of the bottom surface 212. The ring may be circular, elliptical or any polygonal shape. The plurality of rings are uniformly concentrically centered on the center 218, that is, the spacing between adjacent two rings is the same. Further, the spacing between each two adjacent two rings gradually decreases in a direction away from the center 218 of the bottom surface 212. It can be understood that the intensity of the light beam 232 is weakened along the direction away from the center 218. Therefore, the structure is advantageous for enhancing the illuminance near the edge of the light guide plate 202, so that the entire light guide plate 202 emits light uniformly. Preferably, the spacing between adjacent two rings is 0.5 to 2 mm. In the plurality of rings, the density of the scattering dots 220 on each ring gradually increases in a direction away from the center 218. The scattering dots 220 are uniformly distributed on the same ring shape, and the spacing between adjacent two scattering dots 220 is 0.1 to 1 mm. The scattering dots 220 can be bumps, grooves or a combination of bumps and grooves. The shape of the scattering dots 220 includes one or more of a triangle, a square, a diamond, and a circle. The scattering dot 220 has a particle diameter of 0.1 to 0.5 mm. The material of the scattering dots 220 is an ink, a titanium compound or a lanthanide compound.

Preferably, the illuminating device 228 is a light emitting diode, and the radiant light is reflected or refracted by the concentrating device 230 to form a cylindrical beam 232. Therefore, the scatter grid 220 is distributed at a center near the center 218 of the bottom surface 212. 218 is a plurality of rings on the center of the circle. Depending on the shape of the light guide plate 202, away from the center 218, i.e., the region near the edge of the bottom surface 212, the scattering dots 220 are distributed over a plurality of n-ring rings, and n is greater than or equal to three. The ring number of the ring and the ring number ratio of the n-ring ring are less than 20:1. And in the excessive region 234 between the ring and the n-ring ring, the scattering dots 220 are distributed on a plurality of arcs centered on the center 218. In this embodiment, the light guide plate 202 has a square shape. Therefore, at a position close to the edge of the bottom surface 212, the scattering dots 220 are distributed on the square ring centered on the center 218 of the bottom surface 212. Specifically, in the present embodiment, 20 scatter scattering dots 220 distributed on the ring are provided on the bottom surface 212 of the square light guide plate 202 having a side length of 50 mm. Wherein, starting from the center 218 of the bottom surface 212, the first 15 circles of the scattering dots 220 are distributed on the ring, and the last 5 circles of the scattering dots 220 are distributed in the square ring. on. Moreover, near the center 218, the diameter of the first ring 230 is greater than 8 mm, so that the light beam 232 emitted by the light source 200 is not scattered by the scattering dots 220 on the ring, and can directly enter the light guide plate 202. The spacing between the adjacent two scattering scattering dots 220 is 1 mm. The shape of the scattering dots 220 is a circular groove having a radius of 0.3 mm, and the spacing between two adjacent scattering dots 220 is 0.6 mm on the same ring shape.

Further, the light-emitting surface 214 of the light guide plate 202 also includes a center (not shown), and the scattering mesh point 220 can be disposed on the light-emitting surface 214 of the light guide plate 202. It can be understood that the scattering dots 220 can also be disposed on both the bottom surface 212 and the light exit surface 214. When the scattering mesh point 220 is disposed on both the bottom surface 212 and the light emitting surface 214, the light beam may be scattered by the scattering mesh point 220 multiple times during the reflection between the bottom surface 212 and the light emitting surface 214 of the light guiding plate 202, so that the light emitting surface 212 is made. The light emitted is more uniform.

The bottom surface 212 and the four side surfaces 216 of the light guide plate 202 may further be provided with an anti-reflection film for enhancing the reflection effect of the bottom surface 212 and the side surface 216. An optical film such as a brightness enhancement film or a scattering film may be disposed on the light emitting surface 214 of the light guide plate 202.

The light guide plate 202 further includes a reflection portion 222. The reflecting portion 222 is disposed at a position corresponding to the light emitting surface 214 of the light guide plate 202 and the center 218 of the bottom surface 212. The reflecting portion 222 is a recess that is recessed into the light guide plate 202 by the light emitting surface 214. The reflecting portion 222 includes a reflecting surface 224 which is a bottom surface of the recess. The reflective surface 224 can be a spherical surface, a conical surface or a conical surface. It can be understood that, because the light-emitting surface 214 of the light guide plate 202 is provided with a reflection portion 222, the reflective surface 224 of the reflection portion 223 can cause a part of the light emitted by the light source 200 to reach the reflective surface 224, and then enter the light guide plate 202 through reflection, thereby making The light distribution of the light-emitting surface 214 of the light guide plate 202 corresponding to the light source 200 may be weakened. At the same time, the light entering the inside of the light guide plate 202 is again scattered by the scattering mesh point 220, and is uniformly emitted to the light emitting surface 214, so that the light distribution of the peripheral region of the light emitting surface 214 corresponding to the light source 210 is correspondingly increased, so that the light guide plate 202 is increased from the light guide plate 202. The light emitted is evenly distributed, thus backing The optical module 20 has a relatively uniform luminance.

It can be understood that the light guide plate 202 provided in this embodiment is not limited to the backlight module 20 provided in this embodiment. That is, the light guide plate 202 can be applied to the backlight module 20 of different structures according to actual needs, so as to improve the light uniformity of the backlight module 20.

The reflector 204 is disposed between the light source 200 and the bottom surface 212 of the light guide plate 202. The shape and area of the reflecting plate 204 correspond to the shape area of the light guiding plate 202. The thickness of the reflector 204 is not limited. To reduce the thickness of the backlight module 20, the thickness of the reflector 204 should be as small as possible. The position of the reflecting plate 204 corresponding to the light source 200 is hollow or transparent, so that the light emitted by the light source 200 can reach the light guiding plate 202. The reflective plate 204 is provided with a reflective film 226 on a surface opposite to the bottom surface of the light guide plate 202. The reflective film 226 can effectively reflect the light emitted from the bottom surface 212 of the light guide plate 202 back into the light guide plate 202, thereby improving the brightness of the backlight module 20. It can be understood that the reflector 204 is an optional structure.

The microprism system 206, the polarization conversion system 208, and the scattering plate 210 are disposed on the light-emitting surface 214 side of the light guide plate 202 in order to further disperse and homogenize the light emitted from the light guide plate 202. The microprism system 206, the polarization conversion system 208, and the diffusion plate 210 are all commonly used components in the backlight module structure of the prior art. The scatter plate 210 is disposed on a side of the light-emitting surface 214 of the light guide plate 202 and spaced apart from the light-emitting surface 214 of the light guide plate 202 for further dispersing and homogenizing the light emitted from the light-emitting surface 214. The polarization conversion system 208 is disposed on the diffusion plate 210 and disposed on a side of the diffusion plate 210 opposite to the light exit surface 214. The polarization conversion system 208 is used to control and adjust the propagation of light according to the polarization direction of the light. The microprism system 206 is disposed on the polarization conversion system 208 and disposed on a side of the polarization conversion system 208 opposite to the light exit surface 214. The microprism system 206 can be a transmissive brightness enhancement film or a reflective brightness enhancement film for effectively adjusting the light emitted from the light guide plate 202, so that the light emitted from the light guide plate 202 has a certain concentration on the whole, thereby adjusting the light guide plate. 202 emits the overall brightness of the light. It can be understood that the microprism system 206. Polarization conversion system 208 and diffuser 210 are an optional structure.

When the backlight module 20 provided in this embodiment is used, the light emitted by the light source 200 forms a cylindrical beam 232. The cylindrical beam 232 passes through the hollow portion of the reflecting plate 204 into the light guiding plate 202 and reaches the reflecting portion 222. A part of the light passes through the reflecting portion 222 and is emitted by the light emitting surface 214. The other part of the light is reflected by the reflective surface 224 to reach the inside of the light guide plate 202, and is reflected multiple times between the bottom surface 212 and the light exit surface 214 of the light guide plate 202 until it is emitted. Since the dot distribution on the light guide plate 202 of the embodiment adopts a circular and square composite distribution structure, the light beam 232 is uniformly scattered to the light exit surface 214 via the circularly distributed scattering mesh point 220 near the center 218 of the bottom surface 212, away from the bottom surface. At the position of 212 center 218, beam 232 is evenly scattered through the square scattering grid point 220 to the edge of square light exit surface 214. Since the edge of the light guide plate 202 is provided with a scattering dot 220 corresponding to the shape of the light guide plate 202, the light beam at the edge of the light guide plate 202 can be uniformly scattered to the edge of the light exit surface 214. Therefore, the light exit surface 214 of the entire light guide plate 202 is 214. The upper illumination is very uniform, and the light uniformity of the backlight module 20 can be improved. The light output uniformity of the backlight module 20 is greater than 85%. The light output uniformity of the backlight module 20 provided in this embodiment is 90%. The backlight module 20 provided in this embodiment can be widely applied to an isometric display device of a liquid crystal display.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

212‧‧‧ bottom

218‧‧‧ Center

220‧‧‧scattering points

234‧‧‧Excessive area

236‧‧‧last circle

238‧‧‧ first round n-ring ring

240‧‧‧ first ring

Claims (19)

A light guide plate comprising: a bottom surface; a light emitting surface opposite to the bottom surface; and a side surface connecting the bottom surface and the light emitting surface; and a plurality of scattering mesh points disposed on the bottom surface or/and the light emitting surface, wherein the improvement is The plurality of scattering dots are distributed on a plurality of rings surrounding the bottom surface or/and the center of the light exiting surface, and the annular shape of the scattering mesh points distributed away from the center of the bottom surface or/and the center of the light exiting surface corresponds to the shape of the light guide plate. The light guide plate of claim 1, wherein the scattering mesh points near the bottom surface or/and the center of the light exit surface are distributed on a plurality of rings centered on the bottom surface or/and the center of the light exit surface, away from the bottom surface and/or the light output. The scattering mesh points at the center of the face are distributed on the n-sided ring, and n is greater than or equal to 3. The light guide plate of claim 2, wherein the ring number of the ring and the ring number ratio of the n-ring ring are less than 20:1. The light guide plate according to claim 2, wherein the scattering mesh points of the excessive region distributed between the circular ring and the n-shaped ring are distributed on a plurality of circular arcs whose center is the center of the bottom surface or the light-emitting surface. The light guide plate of claim 1, wherein the density of the scattering dots on each of the plurality of rings gradually increases in a direction away from the bottom surface or/and the center of the light exit surface. The light guide plate of claim 1, wherein the scattering mesh points are evenly distributed on the same ring shape, and a spacing between adjacent two scattering mesh points is 0.1 to 1 mm. The light guide plate of claim 1, wherein a spacing between the adjacent two rings is the same, and a spacing between adjacent two rings is 0.5 to 2 mm. The light guide plate of claim 1, wherein a spacing between each two adjacent two annular rings gradually decreases in a direction away from a bottom surface or/and a center of the light exit surface. The light guide plate of claim 1, wherein the shape of the scattering mesh point comprises one or more of a triangle, a square, a diamond, and a circle. The light guide plate of claim 1, wherein the scattering dot has a particle diameter of 0.1 to 0.5 mm. The light guide plate of claim 1, wherein the scattering dot is a bump, a groove or a combination of a bump and a groove, and the material is an ink, a titanium compound or a lanthanide compound. The light guide plate of claim 1, wherein the light guide plate further comprises at least one reflection portion disposed at a position corresponding to a center of the light exit surface of the light guide plate and recessed into the interior of the light guide plate. A backlight module includes: a light guide plate, the light guide plate includes a bottom surface, a light exit surface opposite to the bottom surface, and a side surface connecting the bottom surface and the light exit surface, and a plurality of scattering mesh points are disposed on the bottom surface or/and a light-emitting surface; the light source is disposed at a position directly below the bottom surface of the light guide plate opposite to the center of the bottom surface; and the improvement is that the plurality of scattering mesh points are distributed around the bottom surface or/and the center of the light-emitting surface The annular shape of the plurality of loops and distributed away from the center of the bottom surface or/and the center of the light exiting surface corresponds to the shape of the light guide plate. The backlight module of claim 13, wherein the backlight module further comprises a reflector disposed between the light source and the bottom surface of the light guide plate, and the position of the reflector corresponding to the light source is hollow or transparent. . The backlight module of claim 14, wherein the reflective plate comprises a reflective film disposed on a surface of the reflective plate near a bottom surface of the light guide plate. The backlight module of claim 13, wherein the backlight module further comprises a microprism system disposed on a side of the light exit surface of the light guide plate. The backlight module of claim 16, wherein the backlight module further comprises a polarization conversion system disposed on a side of the microprism system away from the light guide plate. The backlight module of claim 17, wherein the backlight module further comprises a diffusing plate disposed on a side of the polarization conversion system away from the light guide plate. The backlight module of claim 13, wherein the light source comprises a light emitting device and a light collecting device.