TWI498641B - Backlight unit and liquid crystal display device including the same - Google Patents

Description

Backlight module and liquid crystal display device having the same

The present invention relates to a liquid crystal display device, and more particularly to a backlight module and a liquid crystal display device having the same.

Until recently, display devices often used cathode-ray tubes (CRTs). At present, many efforts and research are being carried out on the development of different types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission displays. And an electro-luminescence display (ELD) for use as a replacement for cathode imaging tubes. Among these flat panel displays, liquid crystal display devices have many advantages such as high resolution, light weight, thin profile, compact size, and low voltage power consumption.

In general, a liquid crystal display device includes two substrates which are spaced apart from each other and face each other, and a liquid crystal material is disposed between the two substrates. The two substrates comprise electrodes, the electrodes facing each other such that a voltage applied between the electrodes induces an electric field through the liquid crystal material. The induced electric field changes the direction of alignment of the liquid crystal and changes the light transmissivity of the liquid crystal display device depending on the intensity of the induced electric field. Therefore, the liquid crystal display device displays an image by the intensity of various different induced electric fields.

Liquid crystal display devices require a backlight module to supply light. Backlight modules are generally classified into two broad categories: edge type and direct type. The side backlight module includes a light source located on one side of the liquid crystal display device. The direct type backlight module includes a light source located at the bottom of the liquid crystal display device.

Please refer to FIG. 1 , which is a schematic diagram of a side-lit backlight module of the prior art. Referring to FIG. 1 , the side backlight module 20 includes a light guide plate 30 , a lamp tube 24 , a reflector 22 , a plurality of optical sheets 29 , and a lamp guiding unit 28 . The light tube 24 is a light source, the reflection plate 22 is located below the light guide plate 30, and the optical sheet 29 is located above the light guide plate 30. The optical sheet 29 includes a diffusion sheet and at least one condensing sheet. A pattern 31 on the lower surface of the light guide plate 30 is used to provide a uniform light emitting plane.

Since the light guide plate 30 and the reflection plate 22 are adjacent to each other, the opposite surfaces of the light guide plate 30 and the reflection plate 22 are generated due to static electricity, so that the light guide plate 30 may be in close contact with the reflection plate 22. The backlight module 20 generates heat during operation, and the heat causes the light guide plate 30 and the reflection plate 22 to expand. However, the light guide plate 30 and the reflection plate 22 have different thermal expansion rates, and the reflection plate 22 is thinner than the light guide plate 30. Therefore, thermal expansion may cause the reflecting plate 22 to wrinkle. The luminance of the display area in the liquid crystal display device corresponds to the wrinkle area generated in the reflection plate 22, and the wrinkle area may be different from the brightness of the other display areas. Therefore, such a change in luminance may cause a defect through the liquid crystal display device, for example, a stain on the display screen of the liquid crystal display device, and the display quality is thus degraded.

In view of the above problems, the present invention is directed to a liquid crystal display device for solving the problems of the limitations and disadvantages of the prior art.

A main object of the present invention is to provide a backlight module and a liquid crystal display device having the same for improving the display quality of the liquid crystal display device.

Another object of the present invention is to provide a backlight module and a liquid crystal display device having the same for providing a backlight module with uniform brightness of the liquid crystal display device.

The features and advantages of the present invention are described in the following description, and a part thereof will be clearly described or learned from the process of the invention. The advantages of the invention will be apparent from and elucidated by the appended claims.

According to the advantages and objects of the present invention, the backlight module of the liquid crystal display panel disclosed in the present invention comprises: a lamp tube, a plurality of optical sheets, a light guide plate and a reflection plate. The light guide plate guides the light of the light tube to the optical sheet; the reflective surface faces the rear surface of the light guide plate; the light guide plate comprises: a plurality of first geometric shapes and a plurality of second geometric shapes. The first geometry is located on the rear surface, the first geometry directly directs light incident to the light guide plate to the optical sheet; the second geometry is located at a peripheral portion of the rear surface to prevent the reflective plate from adhering to the light guide plate; the second geometric shape The density is less than the density of the first geometry.

According to another aspect of the present invention, a backlight module of a liquid crystal display panel disclosed in the present invention includes: a lamp tube, a plurality of optical sheets, a light guide plate and a reflection plate. The light guide plate guides the light of the light tube to the rear surface of the optical sheet; the reflective surface faces the rear surface of the light guide plate; the light guide plate comprises: a plurality of first geometric shapes and a plurality of second geometric shapes. The first geometric shape is located on the rear surface, the first geometric shape directly directs light incident to the light guide plate to the optical sheet; the second geometric shape is located at a peripheral portion of the rear surface; the area of the second geometric shape is equal to or about 10% smaller than the guide The area of the peripheral portion of the surface behind the light panel.

According to a second aspect of the present invention, in a backlight module of a liquid crystal display panel disclosed in the present invention, a backlight module has a lamp tube, a plurality of optical sheets, a light guide plate and a reflection plate. The light guide plate guides the light tube of the tube to the optical sheet, and the reflector surface guides the rear surface of the light board. The method includes: providing a plurality of first geometries on a rear surface of the light guide plate for directly guiding light incident to the light guide plate to a rear surface of the optical sheet; and providing a plurality of second geometric shapes on a periphery of a surface behind the light guide plate The part is configured to prevent the reflective plate from adhering to the light guide plate, and the size of the second geometric shape is larger than the size of the first geometric shape.

The above description of the present invention and the following description of the embodiments of the present invention are intended to illustrate and explain the spirit and principles of the invention, and to provide further explanation of the scope of the invention.

The features and implementations of the present invention are described in detail below with reference to the drawings.

Please refer to FIG. 2, which is a schematic diagram of a liquid crystal display device according to an embodiment of the present invention. As shown in FIG. 2, the liquid crystal display device includes a liquid crystal panel 210, a backlight module 220, a main support member 230, a lower cover 250, and an upper cover 240.

The backlight module 220 includes a reflector 222, a light guide 226, a tube 224, and a plurality of optical sheets 229. The reflector 222 is located on the lower cover 250, the light guide plate 226 is located on the reflector 222, the tube 224 is located on one side of the light guide plate 226, and the optical sheet 229 is located on the light guide plate 226. The light emitted by the tube 224 is incident on the input portion of the light guide plate 226, and is conducted and completely reflected in the light guide plate 226, and uniformly diffused on the front surface of the light guide plate 226. Therefore, the light guide plate 226 supplies a uniform light emitting plane to the liquid crystal panel 210. The pattern of the lower surface of the light guide plate 226 is used to create a more uniform light emitting plane.

The reflector 222 reflects the light back to the light guide 226 and increases the brightness. The optical sheet 229 may include a diffusion sheet and at least one condensing sheet. Therefore, the optical sheet 229 diffuses and condenses light passing through the light guide plate 226 to supply a more uniform light-emitting plane to the liquid crystal panel 210.

The main support member 230 has a rectangular frame and is combined with the upper cover 240 and the lower cover 250 to sandwich the liquid crystal panel 210 and the backlight module 220 therein. The upper cover 240 has a rectangular frame and covers a peripheral portion of the liquid crystal panel 210. The lower cover 250 covers and supports the backlight module 220 under the liquid crystal display device.

The liquid crystal panel 210 is configured to display images. The liquid crystal panel 210 includes a first substrate 212, a second substrate 214, and a liquid crystal layer. The liquid crystal layer is interposed between the first substrate 212 and the second substrate 214. In the first substrate 212, a plurality of gate lines and a plurality of data lines (not labeled) are interdigitated with each other to define a plurality of pixel regions. In each of the pixel regions, a thin film transistor is formed and connected to the corresponding gate and data lines, and the pixel electrode is coupled to the thin film transistor. In the second substrate 214, red, green, and blue color filter patterns are formed in respective pixel regions, and a black matrix is formed and corresponds to gate lines, data lines, and Thin film transistor. In addition, the first alignment layer and the second alignment layer may be on the inner surfaces of the first substrate 212 and the second substrate 214, respectively. In addition, a seal pattern may be provided and extended along the peripheral portions of the first substrate 212 and the second substrate 214 to adhere to the first substrate 212 and the second substrate 214. In addition, a first polarizing plate and a second polarizing plate are attached to the outer surfaces of the first substrate 212 and the second substrate 214, respectively.

At least one printed circuit board (PCB) 218 can be coupled to the liquid crystal panel 210 through a connection portion 216, such as a flexible circuit board or a tape carrier package (tape) Carrier package, TCP). During the assembly process, the connecting portion 216 is bent and the printed circuit board 218 is disposed on one side of the main support member 230 or the lower end of the lower cover 250.

Please refer to FIG. 3, which is a schematic diagram of a backlight module of a liquid crystal display device according to an embodiment of the present invention. As shown in FIG. 3, the backlight module 220 includes a reflector 222, a light guide plate 226, a bulb 224, and a plurality of optical sheets 229. The reflector 222 faces the lower cover 250 (as shown in FIG. 2), the light guide plate 226 is located on the reflector 222, the tube 224 faces one side of the light guide plate 226, and the optical sheet 229 is positioned on the light guide plate 226. The backlight module 220 further includes a lamp guiding unit 228. The lamp guiding unit 228 supports the lamp tube 224, and the lamp guiding unit 228 has an opening portion that faces the light guide plate 226. The lamp guiding unit 228 surrounds and protects the lamp tube 224, and reflects light to the edge of the light guide plate 226.

The light guide plate 226 provides a light emitting plane to the liquid crystal panel 210 by completely reflecting the light of the bulb 224. In addition, the light guide plate 226 may include a predetermined pattern to enhance the uniformity of the light emitting plane. The light guide plate 226 may be made of a plastic material such as polymethylmethacrylate (PMMA), acrylic resin or polycarbonate (PC) material.

The lamp tube 224 can be one of a cold cathode fluorescent lamp (CCFL) and an external electrode fluorescent lamp (EEFL). Alternatively, a light emitting diode (LED) can be used as a light source along one side of the light guide plate 226. When a light-emitting diode is used as the light source, the lamp guiding unit 228 is not required.

Please refer to FIG. 4 , which is a schematic plan view of a light guide plate of a backlight module according to an embodiment of the invention. As shown in FIG. 4, the lower surface of the light guide plate 226 includes a first area A and a second area B. The second region B is on a peripheral portion of the lower surface and surrounds the first region A. The second region B may have a width, for example, a distance between the edge of the first region A and the edge of the light guide plate 226, which ranges from about 0.5 mm to 5 mm.

A first geometric feature pattern (also referred to as a first geometric pattern) 211 is formed in the first region A below the light guide plate 226, and a second geometric feature pattern 221 (also referred to as a second geometric pattern) is formed in In the second region B below the light guide plate 226. Each of the first geometric feature pattern 211 and the second geometric feature pattern 221 may have, for example, an appearance of one of an ellipse, a polygon, and a circle. Each of the first geometric feature pattern 211 and the second geometric feature pattern 221 may be, for example, a hologram pattern. The first geometric feature pattern 211 and the second geometric feature pattern 221 may be formed by using a printing method or an injection molding method.

The first geometric feature pattern 211 and the second geometric feature pattern 221 may be formed together with the light guide plate 226. According to an embodiment of the invention, the first geometric feature pattern 211 and the second geometric feature pattern 221 may be the same material as the light guide plate 226. According to another embodiment of the present invention, the first geometric feature pattern 211 and the second geometric feature pattern 221 may be different materials from the light guide plate 226.

In accordance with an embodiment of the invention, a diffuser (not labeled) may be provided between the reflector 222 and the light guide 226.

The first geometric feature pattern 211 diffuses light to direct light incident on the light guide plate 226. Due to the first geometric feature pattern 211, light incident on the light guide plate 226 is conducted and completely reflected in the light guide plate 226. Therefore, a uniform light emitting plane is generated and supplied to the liquid crystal panel 210. The first geometric feature pattern 211 has a large size and/or a first geometric feature pattern 211 that is dense enough to deliver a substantial portion of the light incident on the light guide plate 226 to the liquid crystal panel 210. According to an embodiment of the invention, the density of the first geometric feature pattern 211 may be different according to the distance from the lamp tube 224 (as shown in FIG. 3) to the first geometric feature pattern 211, and thus used to control the guide. The reflection path of the light event on the light panel 226. For example, this density may increase as the distance from the tube 224 to the first geometric feature pattern 211 increases. Thus, the density of the first geometric feature pattern 211 that is closer to the tube 224 is less than the density of the first geometric feature pattern 211 that is further from the tube 224.

The size of each of the first geometric feature pattern and the second geometric feature pattern ranges from about 50 microns to 200 microns. The size of the first geometric feature pattern and the second geometric feature pattern may depend on the size, such as the diagonal size of the liquid crystal display panel. The distance between the first geometric feature patterns 211 increases with the distance from the first geometric feature pattern 211 to the bulb 224.

The second geometric feature pattern 221 is located in the second region B to prevent the light guide plate 226 from being adsorbed to the reflective plate 222 due to static electricity. The size of the second geometric feature pattern 221 may be greater than or equal to the size of the first geometric feature pattern 211. Moreover, the density of the second geometric feature pattern 221 may be less than the density of the first geometric feature pattern 211. In accordance with an embodiment of the invention, the density of the second geometric feature pattern 221 is less than the lowest density of the first geometric feature pattern 211 that is closest to the tube 224. The second geometric feature pattern 221 prevents a bright line due to reflection of light incident on the second region B, which is an event above the upper and lower edges of the light guide plate 226. Compared to the first geometric feature pattern 211, the second geometric feature pattern 221 does not diffuse light events on the light guide plate 226. Further, the second geometric feature pattern 221 prevents the light guide plate 226 and the reflection plate 222 from adhering to each other due to static electricity.

The distance between adjacent patterns in the second geometric feature pattern 221 may be several hundred micrometers, and the area of the second geometric feature pattern 221 may be equal to or about 10% smaller than the area of the second region B. For example, the distance between adjacent patterns in the second geometric feature pattern 221 ranges from about 250 microns to about 900 microns. When the density of the second geometric feature pattern is 10% smaller than the second region B, the effect on the light is very slight. For example, when the density of the second geometric feature pattern is about 5% smaller than the second region B, significant changes in light are not perceived.

According to an embodiment of the invention, when the first geometric feature pattern 211 is close to the tube, the size of the pattern is about 50 microns, and the distance between the patterns in the first geometric feature pattern 211 may be about 140 microns. When the first geometric feature pattern 211 is further away from the tube, the size of the pattern is about 50 microns, and the distance between the patterns in the first geometric feature pattern 211 may be about 5 microns.

Since the light guide plate 226 is not adsorbed to the reflective plate 222 due to the second geometric feature pattern 221, even when the backlight module 220 generates heat during operation, the reflective plate 222 can be prevented from being thermally expanded and guided. The light plate 226 is different to cause wrinkles. Therefore, the situation in which the brightness in the display screen is different can be avoided due to the wrinkles, and the display quality can be improved accordingly.

The second geometric feature pattern 221 can be formed simultaneously with the first geometric feature pattern 211 via the use of a printing method or an injection molding technique. Therefore, a program that additionally forms the second geometric feature pattern 221 is not required.

Please refer to FIG. 5A, which is an enlarged schematic view of a region C of "FIG. 4" according to the present invention. Please refer to FIG. 5B, which is a schematic diagram of a geometric feature pattern according to another embodiment of the present invention. Please refer to "5A" and "5B" as long as the second geometric feature pattern 221 does not greatly affect the diffusion of light as much as the first geometric feature pattern 211 of the first region A. The second geometric feature pattern 221 of the second region B can have various arrangements. In other words, the first area A can be a more efficient area for diffusing light and providing light to the liquid crystal panel 210 (shown in FIG. 2) than the second area B. Thus, the second geometric feature pattern 221 can have a density that is less than the density of the first geometric feature pattern 211 and can have a distance D of between a few hundred microns.

According to an embodiment of the invention, the geometric features of the first pattern 211 and the second pattern 221 may have other shapes. For example, one or both of the geometric features of the first pattern and the second pattern may be a prism pattern or a lenticular pattern.

While the present invention has been described above in terms of the preferred embodiments thereof, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. The patent protection scope of the invention is subject to the definition of the scope of the patent application attached to the specification.

20. . . Backlight module

twenty two. . . Reflective plate

twenty four. . . Lamp

28. . . Lamp guiding unit

29. . . Optical sheet

30. . . Light guide

31. . . pattern

210. . . LCD panel

211. . . First geometric feature pattern

212. . . First substrate

214. . . Second substrate

216. . . Connection

218. . . A printed circuit board

220. . . Backlight module

221. . . Second geometric feature pattern

222. . . Reflective plate

224. . . Lamp

226. . . Light guide

228. . . Lamp guiding unit

229. . . Optical sheet

230. . . Main support

240. . . Upper cover

250. . . lower lid

A. . . First area

B. . . Second area

C. . . region

D. . . distance

1 is a schematic view of a side-side backlight module of the prior art;

2 is a schematic view of a liquid crystal display device according to an embodiment of the present invention;

3 is a schematic diagram of a backlight module of a liquid crystal display device according to an embodiment of the present invention, which is shown in FIG. 2;

4 is a schematic plan view of a light guide plate of a backlight module according to an embodiment of the invention;

Figure 5A is an enlarged schematic view of a region C of "Fig. 4" according to the present invention;

Figure 5B is a schematic illustration of a geometric feature pattern in accordance with another embodiment of the present invention.

210. . . LCD panel

212. . . First substrate

214. . . Second substrate

216. . . Connection

218. . . A printed circuit board

220. . . Backlight module

222. . . Reflective plate

224. . . Lamp

226. . . Light guide

228. . . Lamp guiding unit

229. . . Optical sheet

230. . . Main support

240. . . Upper cover

250. . . lower lid

Claims (19)

A backlight unit of a liquid crystal display panel includes: a lamp; a plurality of optical sheets; a light guide guiding the tube Light to the optical sheets, wherein the light guide plate comprises a first region and a second region located around the peripheral portion and surrounding the first region; and a reflector facing a rear surface of the light guide plate; The light guide plate includes: a plurality of first geometric shapes including one of an ellipse and a polygon, located in the first region of the rear surface of the light guide plate, the first geometric shapes directly guiding the incident directly Light to the optical sheet on the light guide plate; and a plurality of second geometric shapes including one of an ellipse and a polygon, located in the second region of the peripheral portion of the rear surface of the light guide plate to prevent the The reflector is adhered to the light guide plate, and a density of the second geometric shapes is smaller than a density of the first geometric shapes. The backlight module of claim 1, wherein the size of the second geometric shapes is greater than or equal to the size of the first geometric shapes. The backlight module of claim 2, wherein a size of each of the first geometric shapes and a size of each of the second geometric shapes is about 50 micrometers (μm) Up to about 200 microns. The backlight module of claim 1, wherein the density of the first geometric shapes is increased according to a distance from the light tube to the first geometric shapes. The backlight module of claim 4, wherein a distance between adjacent ones of the first geometric shapes ranges from about 5 microns to about 140 microns. The backlight module of claim 1, wherein a distance between adjacent geometric shapes of the second plurality of geometries ranges from about 250 microns to about 900 microns. The backlight module of claim 1, wherein an area of the second geometric shapes is equal to or about 10% smaller than an area of the peripheral portion of the rear surface of the light guide plate. The backlight module of claim 1, wherein a width of the peripheral portion ranges from about 0.5 millimeters (mm) to about 5 millimeters. The backlight module of claim 1, further comprising a lamp guide, the lamp guiding unit supporting the lamp on one side of the light guide plate, and the lamp guiding unit reflecting the light The light from the tube is directed to the light guide. A liquid crystal display device comprising the backlight module of claim 1, further comprising a liquid crystal display panel, wherein the liquid crystal display panel displays images via light from the optical sheets. A backlight module of a liquid crystal display panel, comprising: a light tube; a plurality of optical sheets; a light guide plate guiding the light of the light tube to a rear surface of the optical sheets, The light guide plate includes a first region and a second region located at a peripheral portion and surrounding the first region; and a reflective plate facing a rear surface of the light guide plate; wherein the light guide plate comprises: a plurality of a geometric shape comprising one of an ellipse and a polygon, located in the first region of the rear surface of the light guide plate, the first geometric shapes substantially directly guiding light incident to the light guide plate to the optical sheets And a plurality of second geometric shapes including one of an ellipse and a polygon, located in the second region of the peripheral portion of the rear surface of the light guide plate, an area of the second geometric shapes being equal to or tied 10% is smaller than an area of the peripheral portion of the rear surface of the light guide plate. The backlight module of claim 11, wherein a density of the second geometric shapes is smaller than a density of the first geometric shapes to prevent the reflective plate from adhering to the light guide plate. The backlight module of claim 11, wherein the size of the second geometric shapes is greater than or equal to the size of the first geometric shapes. The backlight module of claim 11, wherein a density of the first geometric shapes is increased according to a distance from the light tube to the first geometric shapes. A liquid crystal display device comprising the backlight module of claim 11, further comprising a liquid crystal display panel, wherein the liquid crystal display panel displays light using light from the optical sheets. A method for controlling light propagation in a backlight module of a liquid crystal display panel, the backlight module having a tube, a plurality of optical sheets, a light guide plate and a reflector, the light guide plate guiding the light of the tube to the The optical sheet, wherein the light guide plate comprises a first region and a second region surrounding the first region and the reflective plate faces a rear surface of the light guide plate, the method comprising: providing a plurality of first Geometry is in the first region of the rear surface of the light guide plate for directly guiding light incident on the light guide plate to a rear surface of the optical sheets, wherein the first geometric shapes comprise an elliptical shape And a plurality of second geometric shapes in the second region of the peripheral portion of the rear surface of the light guide plate for preventing the reflective plate from adhering to the light guide plate, wherein the second geometric shapes One of an ellipse and a polygon is included, and the second geometric shapes are larger than the first geometric shapes. The method of claim 16, comprising modifying a density of the first geometric shapes based on a distance from the tube to the first geometric shapes. The method of claim 16, comprising increasing a density of the first geometric shapes based on a distance from the tube to the first geometric shapes. The method of claim 16, wherein an area of the second plurality of geometries is equal to or about 10% less than an area of the peripheral portion of the rear surface of the light guide plate.