TWI396012B - Backlight module and display apparatus having the same - Google Patents

Description

Backlight module and display having the same

The present invention relates to a surface light source device, and more particularly to a backlight module and a display having the same.

With the advancement of flat display technology and the advantages of flat panel display, such as light weight, small size and power saving, flat panel displays have become more and more popular. Common flat panel displays include liquid crystal display, plaama diaplay panel (PDP), organic light emitting diode display (OLED display), and electrophoretic display (EPD), among which liquid crystal The display has the highest penetration rate.

The liquid crystal display includes a liquid crystal display panel (LCD panel) and a backlight module, wherein the backlight module is used to provide a surface light source to the liquid crystal display panel. A conventional backlight module uses a cold cathode fluorecent lamp (CCFL) as a light source, but the use of a cold cathode fluorescent lamp limits the thinning of the liquid crystal display. Therefore, light emitting diodes (LEDs) having energy saving and environmental protection characteristics such as lightness, power saving, and mercury-free have been widely used in backlight modules.

FIG. 1 is a schematic diagram of a conventional direct type backlight module using a light emitting diode. Referring to FIG. 1 , a conventional direct-lit backlight module 100 includes a back plate 110 , a plurality of light-emitting diodes 120 , and a diffusion plate 130 . The light-emitting diodes 120 are arranged in an array on the back plate 110 , and the light-emitting diodes 120 . The light emitting surface 122 faces the diffusion plate 130. The light emitting diode 120 is used to provide light 124 to the diffuser plate 130, and the diffuser plate 130 is used to convert the light 124 into a surface light source.

Since the light 124 provided by the light-emitting diode 120 has high directivity, the area of the diffuser plate 130 directly above the light-emitting diode 120 is brighter, resulting in poor uniformity of the surface light source. 2A shows a pattern of a surface light source provided by a conventional direct type backlight module using a light emitting diode, and FIG. 2B is a brightness analog value along a line L1 and a line L2 in FIG. 2A. This analog value was obtained under the condition that the pitch between the light-emitting diodes 120 was 28 millimeters and the distance between the back plate 110 and the diffusion plate 130 was 8 mm. As can be seen in Figure 2A, the surface light source 102 has a plurality of distinct circular bright regions 103, and the locations of the circular bright regions 103 are corresponding to the locations of the light emitting diodes. As can be seen from FIG. 2B, the illuminance of the circular bright area 103 of the surface light source 102 is higher than 1250 watts/square meter (W/m ² ), and the illuminance of the dark area 104 between the circular bright areas 103 is Less than 500W/m ² .

In general, the uniformity of the surface light source is calculated by dividing the minimum illumination of the surface source by the maximum illumination. In FIG. 2B, the minimum illumination of the surface light source 102 is about 450 W/m ² and the maximum illumination is about 1440 W/m ² . In other words, the uniformity of the surface light source 102 passing through the diffusion plate 130 is about 31%, so the uniformity of the surface light source 102 is not good.

In order to improve the uniformity of the surface light source 102, the distance between the light guide plate 130 and the light emitting diode 120 is increased to increase the light mixing distance of the light 124, or the number of the light emitting diodes 120 is increased. However, increasing the distance between the light guide plate 130 and the light emitting diode 120 increases the thickness of the direct type backlight module 100. On the other hand, since the light 124 provided by the light-emitting diode 120 has high directivity, even if the number of the light-emitting diodes 120 is greatly increased, the uniformity of the surface light source 102 cannot be effectively improved. Moreover, increasing the number of the light emitting diodes 120 not only increases the production cost of the direct type backlight module 100, but also increases the power consumption of the direct type backlight module 100.

The invention provides a backlight module to achieve the advantages of thin thickness and power saving.

The present invention further provides a display to achieve the advantages of thin thickness and power saving.

To achieve the above advantages, the present invention provides a backlight module including a back plate, a plurality of light source groups, and a plurality of light guiding elements. The light source groups are spaced apart on the backplane, and each light source group includes a plurality of point light sources. The light guiding elements are disposed on the backboard and are respectively located beside the light source group. Each light guiding element extends along a predetermined direction and has a bottom surface, a first reflecting surface and a second reflecting surface. The bottom surface faces the back plate, and the first reflecting surface extends from the bottom surface to the point source of the corresponding light source group, and the first reflecting surface is a curved surface. The second reflecting surface is connected between the bottom surface and the first reflecting surface. The light emitting surface of the point source of each light source group faces the first reflecting surface of the corresponding light guiding element.

In an embodiment of the invention, each of the light source groups is a line light source, and the point light sources of each light source group are arranged in a predetermined direction.

In an embodiment of the invention, the light source group shares one substrate, and the point light source of the light source group is disposed on the substrate.

In an embodiment of the invention, the backlight module further includes a reflective sheet disposed on the substrate.

In an embodiment of the invention, the light source groups include a plurality of substrates disposed on the backplane, and each of the substrates is configured to carry a portion of the light source group. In addition, the backlight module further includes a plurality of reflective sheets respectively disposed on the substrate.

In an embodiment of the invention, each of the light guiding elements includes a substrate and at least one reflective sheet covering a portion of the substrate, and the first reflective surface and the second reflective surface are surfaces of the reflective sheet.

In an embodiment of the invention, the reflective sheet comprises a white reflective sheet or a silver reflective sheet.

In an embodiment of the invention, the silver reflective sheet is made of metal or stacked by a multilayer film.

In an embodiment of the invention, each of the light guiding elements is made of a highly reflective material, and the reflectivity of the highly reflective material is greater than or equal to 70%.

In an embodiment of the invention, the bottom surface of each of the light guiding elements is provided with a fixing pin, and the fixing pin is engaged with the backing plate.

In an embodiment of the invention, each of the light guiding elements is locked to the backboard through the locking member.

In an embodiment of the invention, the point source comprises a light emitting diode.

In an embodiment of the invention, the backlight module further includes a diffusion plate opposite to the back plate, and the light source group and the light guiding element are disposed between the diffusion plate and the back plate.

In an embodiment of the invention, the backlight module further includes at least one optical film opposite to the light emitting surface of the diffusing plate.

To achieve the above advantages, the present invention further provides a display comprising a display panel and the backlight module described above.

In an embodiment of the invention, the display panel comprises a liquid crystal display panel, a flexible display panel or a touch panel.

In the backlight module of the present invention, the first reflecting surface and the second reflecting surface of the light guiding element can reflect the light provided by the point source, so that the light can be evenly distributed, so that the thickness of the backlight module can be increased without increasing the point. In the case of the number of light sources, the uniformity of the surface light source provided by the backlight module is improved. Thus, the backlight module of the present invention and the display using the same can have the advantages of thin thickness and power saving.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

3 is a schematic view of a display according to an embodiment of the present invention, and FIG. 4 is a perspective view of a portion of the components of the backlight module of FIG. Referring to FIG. 3 and FIG. 4 , the display 300 of the present embodiment includes a display panel 310 and a backlight module 200 . The backlight module 200 is disposed on one side of the display panel 310 to provide a surface light source to the display panel 310 . The display panel 310 can be a liquid crystal display panel, a flexible display panel, or a touch panel, but is not limited thereto.

The backlight module 200 includes a back plate 210, a plurality of light source groups 220, and a plurality of light guiding elements 230. The light source groups 220 are spaced apart from each other on the back plate 210, and each of the light source groups 220 includes a plurality of point light sources 222. The light guiding elements 230 are disposed on the back plate 210 and are respectively located beside the light source group 220. In other words, each light guiding element 230 corresponds to one light source group 220. In addition, each light guiding element 230 extends along a predetermined direction D and has a bottom surface 232, a first reflecting surface 234 and a second reflecting surface 236. The bottom surface 232 faces the back plate 210, and the first reflecting surface 234 extends from the bottom surface 232 to the point source 222 of the corresponding light source group 220, and the first reflecting surface 234 is a curved surface. The second reflecting surface 236 is connected between the bottom surface 232 and the first reflecting surface 234. The light emitting surface 223 of the point light source 222 of each light source group 220 faces the first reflecting surface 234 of the corresponding light guiding element 230.

In the above backlight module 200, each light source group 220 is, for example, a line light source, and the point light sources 222 of each light source group 220 are arranged along a predetermined direction D. That is, the line source includes a plurality of point sources 222 arranged in a line. The point light source 222 can be a light emitting diode, but is not limited thereto. In addition, the light source groups 220 are shared by one substrate 224, and the point light sources 222 of the light source groups 220 are disposed on the substrate 224.

Each of the light guiding elements 230 includes, for example, a substrate 231 and at least one reflective sheet 233 covering the partial substrate 231, and the first reflective surface 234 and the second reflective surface 236 are, for example, surfaces of the reflective sheet 233. In the present embodiment, the reflection sheet 233 does not cover the bottom surface 232. In addition, the reflective sheet 233 may be a white reflective sheet or a silver reflective sheet, but is not limited thereto. The silver reflective sheet may be made of metal or stacked of a multilayer film. Specifically, the silver reflection sheet in which the multilayer film is stacked is, for example, a stack of two polymer films having different refractive indices. In addition, in another embodiment, the light guiding element 230 can also be made directly of a highly reflective material without the need to additionally use the reflective sheet 233. The reflectance of the above highly reflective material is, for example, greater than or equal to 70%.

The backlight module 200 of the embodiment may further include a reflective sheet 240 disposed on the substrate 224. Similar to the above-mentioned reflective sheet 233, the reflective sheet 240 may be a white reflective sheet or a silver reflective sheet, but is not limited thereto. In addition, the backlight module 200 may further include a diffusion plate 250 opposite to the back plate 210 , and the light source group 220 and the light guiding element 230 are disposed between the diffusion plate 250 and the back plate 210 . In addition, the backlight module 200 may further include at least one optical film 260 opposite to the light emitting surface 252 of the diffusion plate 250. The optical film 260 may be a diffusion film, a brightness enhancement film, or the like.

In this embodiment, since the first reflective surface 234 of the light guiding element 230 extends above the point source 222 of the corresponding light source group 220, the light 225 provided by the point source 222 is reflected by the first reflecting surface 234 instead of It will be passed directly to the diffuser plate 250 located directly above the point source 222. In this way, the area of the diffuser plate 250 directly above the point light source 222 can be prevented from being too bright. In addition, the reflective sheet 240 and the second reflective surface 236 of the light guiding element 230 can be used to reflect the light 225 reflected by the first reflective surface 234. The light 225 can be uniformly transmitted to the diffuser plate 250, such that the diffuser plate 250 can convert the light 225 into a uniform surface light source. In addition, by reflecting the light 225 by the light guiding element 230 and the reflection sheet 240 disposed between the substrate 210 and the diffusion plate 250, the total length of the path of the light 225 transmitted to the diffusion plate 250 can be increased, and the light 225 is transmitted to the diffusion plate 250. Can evenly mix before. Thus, the spacing between the substrate 210 and the diffusion plate 250 can be reduced, so that the backlight module 200 of the embodiment can achieve the advantage of thin thickness. Furthermore, in this embodiment, by converting the point light source 222 into a large-area surface light source, the amount of the point light source 222 can be reduced, so that the power consumption can be reduced, thereby achieving the advantage of power saving.

5A shows a pattern of surface light sources provided by the backlight module of FIG. 3, and FIG. 5B shows brightness simulation values along a line L3 and a line L4 in FIG. 5A. The analog value is obtained by using the light-emitting diode 120 of FIG. 1 as the point light source 222, and the distance between the point light sources 222 is 28 mm, and the distance between the back plate 210 and the diffusion plate 250 is 8 mm. The resulting analog value. It can be seen from FIG. 5A that the surface light source 202 provided by the backlight module 200 of the present embodiment does not have a distinct circular bright area after passing through the diffusion plate 250. In addition, comparing FIG. 2B with FIG. 5B, under the same conditions, the backlight module 200 of the present embodiment is provided with the light guiding element 230, so that the difference between the maximum illuminance and the minimum illuminance of the surface light source 202 can be significantly reduced.

More specifically, in FIG. 5B, the minimum light illumination surface 202 is approximately 520W / m ^2, and the maximum illuminance of about 725W / m ^2. In other words, the uniformity of the surface light source 202 is about 72%. Compared with the conventional art, the uniformity of the surface light source 102 passing through the diffusion plate 130 is only 31%. In the present embodiment, the uniformity of the surface light source 202 passing through the diffusion plate 250 has been greatly improved to 72%. In this way, the surface light source 202 is further homogenized by the optical film 260, so that the uniformity of the surface light source 202 can meet the requirements. Therefore, the backlight module 200 of the embodiment can provide a surface light source with better uniformity and meets the requirements.

In view of the above, since the backlight module 200 has the advantages of thinness and power saving in addition to the surface light source with good uniformity, the display 300 using the backlight module 200 can have good display quality, thin thickness and save The advantages of electricity.

FIG. 6 is a perspective view of a backlight module according to another embodiment of the present invention. Referring to FIG. 6 , the structure and advantages of the backlight module 200 a of the present embodiment are similar to those of the backlight module 200 . The difference is that the light source groups 220 a of the backlight module of the embodiment include multiple disposed on the back plate 210 . Each of the substrates 224a is used to carry a portion of the light source group 220a. In more detail, in the present embodiment, the partial light source groups 220a share one substrate 224a to form one light source unit 225, and the back plate 210 is provided with a plurality of light source units 225. In FIG. 6, the light source unit 225 is composed of two light source groups 220a, but the present invention does not limit the number of light source groups 220a of the light source unit 225. In this embodiment, a larger size backlight module can be fabricated by arranging a plurality of light source units 225. In addition, similar to the backlight module 200 described above, each of the substrates 224a of the embodiment may be coated with a reflection sheet 240.

FIG. 7 is a schematic diagram of a backlight module according to another embodiment of the present invention. Referring to FIG. 7 , the backlight module 200 b of the present embodiment is similar to the backlight module 200 . The difference is that the bottom surface 232 of each light guiding component 230 b of the backlight module 200 b of the embodiment is provided with a fixing pin 238 , and The fixing pin 238 is engaged with the back plate 210. Specifically, the back plate 210 is provided with a plurality of first through holes 212, and the substrate 224 is provided with a second through hole 227 corresponding to the first through holes 212. The fixing pin 238 is engaged with the back plate 210 through the corresponding first through hole 212 and the second through hole 227 . In this embodiment, the light guiding element 230 is fixed to the back plate 210 by the fixing pin 238, so that the light guiding element 230b can be easily disassembled.

FIG. 8 is a schematic diagram of a backlight module according to another embodiment of the present invention. Referring to FIG. 8 , the backlight module 200 c of the present embodiment is similar to the backlight module 200 b . The difference is that the backlight module 200 c of the embodiment is used to lock the light guiding component 230 c to the back plate 210 by using the locking component 270 . . Specifically, the light guiding element 230c is provided with a locking hole 239, and the first through hole 212 of the back plate 210 and the second through hole 227 of the substrate 224 are, for example, locking holes, and the locking member 270 is correspondingly disposed through the corresponding hole. The locking hole 239, the first through hole 212 and the second through hole 227 are used to lock the light guiding element 230c to the back plate 210. The lock 270 is, for example, a screw, but is not limited thereto. In addition, the second reflective surface 236 of the light guiding element 230c is, for example, a surface of the reflective sheet, that is, the present embodiment covers the locking hole 239 by the reflective sheet. In this embodiment, the light guiding element 230c is fixed to the back plate 210 by the fastener 270, so that the light guiding element 230c can be easily disassembled.

It should be noted that the backlight module 200 of the display 300 of FIG. 3 can be replaced with one of the backlight modules 200a, 200b, and 200c described above.

In summary, in the backlight module of the present invention, the first reflecting surface of the light guiding element extends above the point light source of the corresponding light source group, so that the area directly above the point light source can be prevented from being too bright. In addition, the first reflective surface and the second reflective surface can reflect the light provided by the point source, so that the light can be evenly distributed, so that the backlight module can be improved without increasing the thickness of the backlight module and increasing the number of point sources. Provides uniformity of the surface source. Therefore, the backlight module of the present invention not only provides a surface light source with good uniformity, but also has the advantages of thin thickness and power saving. Thus, the display using the backlight module can have the advantages of good display quality, thin thickness, and power saving.

Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention, and it is intended to be a part of the invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims.

100. . . Direct type backlight module

102. . . Surface light source

103. . . Round bright area

104. . . dark zone

110. . . Backplane

120. . . Light-emitting diode

122. . . Luminous surface

124. . . Light

130. . . Diffuser

200, 200a, 200b, 200c. . . Backlight module

202. . . Surface light source

210. . . Backplane

212. . . First consistent hole

220, 220a. . . Light source group

222. . . point Light

223. . . Luminous surface

224, 224a. . . Substrate

225. . . Light

227. . . Second through hole

230, 230b, 230c. . . Light guiding element

231. . . Substrate

232. . . Bottom

233, 240. . . A reflective sheet

234. . . First reflecting surface

236. . . Second reflecting surface

238. . . Fixed pin

239. . . Locking hole

250. . . Diffuser

252. . . Glossy surface

260. . . Optical film

270. . . Lock firmware

300. . . monitor

310. . . Display panel

FIG. 1 is a schematic diagram of a conventional direct type backlight module using a light emitting diode.

FIG. 2A shows a pattern of a surface light source provided by a conventional direct type backlight module using a light emitting diode.

Fig. 2B is an illuminance simulation value along the straight line L1 and the straight line L2 in Fig. 2A.

3 is a schematic diagram of a display in accordance with an embodiment of the present invention.

4 is a perspective view of a portion of the components of the backlight module of FIG. 3.

FIG. 5A shows a pattern of a surface light source provided by the backlight module of FIG. 3. FIG.

Fig. 5B is an illuminance simulation value along the straight line L3 and the straight line L4 in Fig. 5A.

FIG. 6 is a perspective view of a backlight module according to another embodiment of the present invention.

FIG. 7 is a schematic diagram of a backlight module according to another embodiment of the present invention.

FIG. 8 is a schematic diagram of a backlight module according to another embodiment of the present invention.

200. . . Backlight module

210. . . Backplane

220. . . Light source group

222. . . point Light

223. . . Luminous surface

224. . . Substrate

225. . . Light

230. . . Light guiding element

232. . . Bottom

234. . . First reflecting surface

236. . . Second reflecting surface

250. . . Diffuser

252. . . Glossy surface

260. . . Optical film

300. . . monitor

310. . . Display panel

Claims (18)

A backlight module includes: a back plate; a plurality of light source groups disposed on the back plate, each light source group includes a plurality of point light sources; and a plurality of light guiding elements disposed on the back plate, and respectively Located adjacent to the light source groups, each light guiding element extends along a predetermined direction and has a bottom surface, a first reflecting surface and a second reflecting surface, the bottom surface facing the back plate, the first reflecting surface is from the The bottom surface extends above the point light sources corresponding to the light source group, and the first reflective surface is a curved surface, and the second reflective surface is connected between the bottom surface and the first reflective surface, wherein each of the light source groups The light emitting surface of the point light source faces the corresponding first reflecting surface of the light guiding element. The backlight module of claim 1, wherein each of the light source groups is a line light source, and the point light sources of each light source group are arranged along the predetermined direction. The backlight module of claim 2, wherein the line source comprises a plurality of point sources arranged in a line. The backlight module of claim 1, wherein the light source groups share a substrate, and the point light sources of the light source groups are disposed on the substrate. The backlight module of claim 4, further comprising a reflective sheet disposed on the substrate. The backlight module of claim 1, wherein the light source groups comprise a plurality of substrates disposed on the backplane, and each of the substrates is configured to carry a portion of the light source groups. The backlight module of claim 6, further comprising a plurality of reflective sheets disposed on the substrate. The backlight module of claim 1, wherein each of the light guiding elements comprises a substrate and at least one reflective sheet covering the substrate, and the first reflective surface and the second reflective surface are The surface of the reflective sheet. The backlight module of claim 1, wherein the reflective sheet comprises a white reflective sheet or a silver reflective sheet. The backlight module of claim 9, wherein the silver reflective sheet is made of metal or stacked by a multilayer film. The backlight module of claim 1, wherein each of the light guiding elements is made of a highly reflective material having a reflectance greater than or equal to 70%. The backlight module of claim 1, wherein the bottom surface of each light guiding element is provided with a fixing pin, and the fixing pin is engaged with the backing plate. The backlight module of claim 1, wherein each of the light guiding elements is locked to the backboard through a lock. The backlight module of claim 1, wherein the point light sources comprise light emitting diodes. The backlight module of claim 1, further comprising a diffusing plate opposite to the backing plate, wherein the light source groups and the light guiding elements are disposed between the diffusing plate and the backing plate. The backlight module of claim 15, further comprising at least one optical film opposite to a light emitting surface of the diffusing plate. A display comprising: a display panel; and a backlight module as claimed in claim 1. The display device of claim 17, wherein the display panel comprises a liquid crystal display panel, a flexible display panel or a touch panel.