TW201426112A - Back light module and display device using same - Google Patents

Abstract

The present invention discloses a back light module and a display device using the same. The back light module includes a light guide plate, a light guide bar and a light source. The light guide plate includes a top surface, a bottom surface and a side surface connecting the top surface to the bottom surface. The top surface includes a light emitting area and a light incident area adjacent to the side surface. The light guide bar includes a light incident surface, a light emitting surface adjacent to the light incident surface and a connecting surface. The light incident surface is disposed face to the light surface. The light emitting surface is disposed face to the light incident area.

Description

Backlight module and liquid crystal display device

The invention relates to a backlight module and a liquid crystal display device.

In recent years, liquid crystal display devices have gradually occupied the mainstream of display products because of their slimness, small footprint, small radiation, and the like, and have gradually replaced conventional cathode ray tube display devices. The liquid crystal display device usually includes a light source, such as a backlight module, to provide the liquid crystal panel with sufficient and uniform planar light.

Please refer to FIG. 1 , which is a perspective view of a backlight module in the prior art. The backlight module 1 includes a light guide plate 12 and a three-point light source 13. Each of the point light sources 13 has a light exiting side 131. The three point light sources 13 are juxtaposed and have a uniform light exiting direction. The light guide plate 12 includes a light-emitting surface 121, a bottom surface 124 disposed opposite to the light-emitting surface 121, and a light-incident surface 123 disposed between the light-emitting surface 121 and the bottom surface 124 and respectively connected to the light-emitting surface 123. The light guide plate 12 is disposed. The light incident surface 123 is disposed on the light exiting surface 131 of the three-point light source 13 for receiving the light emitted by the three-point light source 13 . The light enters the light guide plate 12 and propagates therein, and is emitted through the light exit surface 121 for use. Provide flat light to the LCD panel.

The point light source 13 is generally a light emitting diode light source, and the light emitting diode has an illumination angle of 110 degrees to 120 degrees due to limitation of its own package structure. Therefore, a certain distance between the point light source 13 and the light incident surface 123 of the light guide plate 12 is maintained, so that the light emitted by the two adjacent point light sources 13 can enter the light guide surface 123 or enter the light guide plate 12. The light-emitting area A of the display panel of the liquid crystal panel is mixed before, so that the light emitted from the light guide plate 12 is relatively uniform. The light guide plate 12 is observed on the side of the light-emitting surface 121, and no obvious bright and dark stripes are formed at the light-emitting area A near the light-incident surface 123. However, as the product is increasingly miniaturized, in the case where the size of the light-emitting area A of the light guide plate 12 is constant, the distance between the point light source 13 and the light guide plate 12 can be shortened or the light-incident surface of the light guide plate 12 can be shortened. 123 to the distance of the light exit area A. The above two structures cause the light emitted by the adjacent two-point light source 13 to be insufficiently mixed before entering the light exiting area A after entering the light guide plate 12, further causing the light guide plate 12 to be observed on the light exiting surface 121 side. Significant bright and dark stripes appear near the light exit area A. Then, the light emitted from the light guide plate 12 is uneven.

In view of this, it is necessary to provide a backlight module that can improve the uniformity of light emission.

In view of this, it is also necessary to provide a liquid crystal display device using the above backlight module.

A backlight module includes a point light source, a light guide plate, and a reflective structure, the light guide plate includes a top surface, a bottom surface opposite to the top surface, and a first side surface on the side of the light guide plate connecting the top surface and the bottom surface; The top surface of the light guide plate includes a light incident region and a light exit region. The light incident region is located at an end of the top surface adjacent to the first side surface. The backlight module further includes a light guide strip, and the light guide strip includes a light-incident surface, a light-emitting surface disposed adjacent to the light-incident surface, and a connection surface connected to the light-incident surface and the light-emitting surface, the light-incident surface of the light guide strip is disposed opposite to the point light source to receive the light generated by the point light source The light-emitting surface of the light-guiding strip is disposed opposite to the light-incident region of the light guide plate to transmit the light to the light guide plate. The reflective structure includes a first reflective structure and a second reflective structure, and the first reflective structure covers a portion of the light-receiving portion a light guide plate, the second reflective structure covers a portion of the light guide strip, and the light generated by the point light source enters the light guide strip via the light incident surface of the light guide strip and changes the travel path via the reflection of the second reflective structure, Surface emitting light guide bar; the surface from the emitted light into the interior of the light guide plate through the light incident region, and then by the reflective structure of the first light reflected from the region of the exit of the guide plate.

A liquid crystal display device includes a liquid crystal panel and a backlight module adjacent to the liquid crystal panel and providing a light source for the liquid crystal panel. The backlight module includes a point light source, a light guide plate, and a reflective structure, and the light guide plate includes a top surface and a bottom surface of the top surface opposite to the first light guide plate and a first side surface connecting the top surface and the bottom surface; a top surface of the light guide plate includes a light incident region and a light exit region, wherein the light incident region is located relative to the light exit region The backlight module further includes an end of the first side surface, the backlight module further includes a light guiding strip, the light guiding strip includes a light incident surface, a light emitting surface disposed adjacent to the light incident surface, and is connected to the light incident surface and the light emitting surface The light incident surface of the light guide strip is disposed opposite to the point light source to receive the light generated by the point light source, and the light emitting surface of the light guide strip is disposed opposite to the light incident area of the light guide plate to transmit the light to The light guide plate includes a first reflective structure and a second reflective structure, the first reflective structure covers a portion of the light guide plate, and the second reflective structure covers a portion of the light guide strip, and the light generated by the point light source After the light incident surface of the light guiding strip enters the light guiding strip and changes the traveling path through the reflection of the second reflective structure, the light guiding strip is emitted through the light emitting surface; the light emitted from the light emitting surface is emitted through the light entering area The light guide plate is inserted into the light guide plate and reflected by the first reflective structure to emit the light guide plate from the light exiting region.

Compared with the prior art, the light emitted by the point source of the backlight module is reflected by the second reflection structure disposed on the connection surface to the light guide plate through the light guide strip, and then reflected by the first reflection structure and then emitted from the light exit area. The light plate extends the propagation path of the light of the point source before entering the light guide plate, and the light mixing effect is good.

Please refer to FIG. 2. FIG. 2 is a perspective exploded view of the first embodiment of the liquid crystal display device of the present invention. The liquid crystal display device 2 includes a liquid crystal panel 22 and a backlight module 23. The backlight module 23 is adjacent to the liquid crystal panel 22 and provides backlighting for the liquid crystal panel 22 .

The backlight module 23 includes a plastic frame 25 , an optical film set 24 , a light guide plate 26 , a light source 27 , a reflective structure 28 , and a light guiding strip 29 . In the present embodiment, the reflective structure 28 is an independent reflective sheet that covers a portion of the light guide plate 26 and the light guide strips 29. In other embodiments, the reflective structure 28 can also be formed directly on the surface of the light guide plate 26 and the light guide strip 29.

Referring to FIG. 3 , the light guide plate 26 includes a top surface 260 , a bottom surface 263 disposed opposite the top surface 260 , and a plurality of side surfaces 265 connecting the top surface 260 and the bottom surface 263 . The top surface 260 includes a light exiting region 262 and a light incident region 261 disposed adjacent to each other. The plurality of side surfaces 265 have a first side surface 266 opposite to the light exiting area 262 at an end of the top surface 260 adjacent to the first side surface 266.

Referring to FIG. 2 , the plastic frame 25 is a hollow frame, and includes four side walls 251 that end to end and a support plate 252 extending from the inner side of the four side walls 251 toward the center of the frame 25 . The support plate 252 divides the space enclosed by the inside of the plastic frame 25 into two parts, one part for accommodating the liquid crystal panel 22 and the other part for accommodating the optical film set 24, the light guide plate 26, the light source 27, the reflective structure 28 and Light guide bar 29. The optical film group 24, the light source 27 and the light guiding strip 29 are located on the top surface 260 side of the light guiding plate 26, wherein the light source 27 is located between the optical film group 24 and the light guiding strip 29. The reflective structure 28 is configured to reflect light leakage of the light guiding strip 29 and the light guide plate 26.

Referring to FIG. 4 , the light guiding strip 29 includes a light incident surface 297 , a light emitting surface 296 disposed adjacent to the light incident surface 297 , and a connecting surface (not labeled) connected to the light incident surface 297 and the light emitting surface 296 . The light-emitting surface 296 is adjacent to and facing the light-input region 261 of the light guide plate 26, and the light-incident surface 297 is located on a side of the light-emitting surface 296 facing the light-emitting region 262 of the light guide plate 26. The joining surface can be a continuously varying curved surface or a composite surface joined by two or more curved planes. In the present embodiment, the shape of the light guiding strip 29 is a cube, and the connecting surface includes a first connecting surface 291 disposed opposite to the light incident surface 297 and a second connecting surface 292 disposed opposite to the light emitting surface 296.

The light source 27 includes a circuit board 271 and at least two light sources 272 disposed on the circuit board 271. Each of the point light sources 272 has a light emitting surface 273 through which light generated by the point light source 272 is emitted.

The reflective structure 28 includes a first reflective structure 283 and a second reflective structure 281. One end of the second reflective structure 281 is disposed at an edge of the first reflective structure 283, and the other end is a free end, and the second reflective structure 281 is The first reflective structure 283 forms a receiving space 280 for receiving the light source 27, the light guiding strip 29 and a portion of the light guiding plate 26. The second reflective structure 281 can extend from one side of the first reflective structure 283 and be bent. The first reflective structure 283 is used to cover a portion of the light guide plate 26; the second reflective structure 281 is used to cover a portion of the light guide strips 29. In the present embodiment, the first reflective structure 283 includes a first reflective portion 288 covering the bottom surface of the light guide plate 26 and a second reflective portion 282 covering the first side surface 266 of the light guide plate 26 . The second reflective structure 281 includes a third reflective portion 285 covering the first connection surface 291 of the light guide strip 29 and a fourth reflective portion 286 covering the second connection surface 292 of the light guide strip 29 . In this embodiment, the reflective structure is a one-piece element, the first reflective portion 288 is a bottom plate, and the second reflective portion 282 is a first bent piece formed by bending one end of the first reflective portion 288. The third reflecting portion 285 and the fourth reflecting portion 286 are the second bent piece and the third bent piece which are sequentially connected. One end of the second reflecting portion 282 is connected to the first reflecting portion 288, and the opposite end is connected to the third reflecting portion 285. One end of the third reflecting portion 285 is connected to the second reflecting portion 282, and the opposite end is opposite to the second reflecting portion 282. The fourth reflecting portions 286 are connected. One end of the fourth reflecting portion 286 is connected to the third reflecting portion 285, and the opposite end is a free end. In the present embodiment, the second reflection portion 282 is coplanar with the third reflection portion 285. Preferably, the second reflecting portion 282 and the third reflecting portion 285 are perpendicular to the first reflecting portion 288 , and the fourth reflecting portion 286 is parallel to the first reflecting portion 288 . The distance between the connection of the third reflection portion 285 and the fourth reflection portion 286 to the connection of the third reflection portion 285 to the second reflection portion 282, that is, the vertical direction of the third reflection portion 285 is first. The width in the direction of the reflective structure 283 is substantially the same as the first connecting surface 291. The width of the second reflecting portion 282 in the direction perpendicular to the first reflecting structure 283 is substantially the same as the height of the first side surface 266. The distance from the free end of the fourth reflecting portion 286 to the third reflecting portion 285, that is, the width of the projection of the fourth reflecting portion 286 to the first reflecting portion 288 is substantially equal to the width of the light incident region 261. In the present embodiment, the width of the light incident region 261 is a vertical distance from the partition of the light incident region 261 and the light exit region 262 to the first side surface 266. The width of the light incident region 261 is substantially equal to the distance from the outer side of the circuit board 271 of the light source 27 that is disposed outside the at least two point light source 272 to the first connection surface 291 of the light guide bar 29.

When assembling, please refer to FIG. 5 and FIG. 6 , the light source 27 and the light guiding strip 29 are directly disposed on the light incident region 261 of the light guide plate 26 , and the light emitting surface 273 of the light source 27 and the light incident surface of the light guiding strip 29 . 297 is oppositely disposed such that light generated by the light source 27 passes through the light incident surface 297 into the light guiding strip 29. The circuit board 271 is disposed at a position adjacent to the light exiting region 262 of the light incident region 261. The light emitting surface 296 of the light guiding strip 29 is disposed opposite to the light incident region 261.

The first reflecting portion 288 of the reflecting structure 28 is disposed on the bottom surface 263 side of the light guide plate 26, and the second reflecting portion 282 is opposite to and attached to the first side surface 266 side. The third reflecting portion 285 is attached to the first connecting surface 291 of the light guiding strip 29 , and the fourth reflecting portion 286 is attached to and covers the second connecting surface 292 of the light guiding strip 29 and the light source 27 .

The optical film group 24 is disposed on the light-emitting region 262 side of the light guide plate 26. The plastic frame 25 houses the light source 27, the light guide plate 26, the optical film group 24, the reflective structure 28, and the light guide strip 29. The liquid crystal panel 22 is disposed on one side of the optical film group 24 and carried by the support plate 252 of the plastic frame 25.

The majority of the light emitted by the light source 27 enters the light guiding strip 29 via the light incident surface 297, and the reflection of the second reflective structure 281 attached to the first connecting surface 291 and the second connecting surface 292 is finally After the light exiting surface 296 is emitted, the light incident surface 26 of the light guide plate 26 enters the light guide plate 26, and the light guide plate 26 is emitted from the light exiting region 262 under the reflection of the first reflective structure 283. A small portion of the light emitted by the light source 27 enters the light guide bar 29 via the light incident surface 297, and is directly emitted from the light exit surface 296, and then enters the light guide plate 26 through the light incident region 261 of the light guide plate 26, in the first reflection. The light guide plate 26 is emitted from the light exiting region 262 under the reflection of the structure 283. In the above structure, when the size of the light exiting region 262 of the light guide plate 26 is not affected, the light-mixing path of the light generated by the point light source 272 is extended by increasing the position of the light guiding strip 29 and changing the setting position of the point light source 272, so that the light is guided. After the light bar 29 propagates and then enters the light guide plate 26, the light guide plate 26 is observed on the light exiting region 262 side, and no obvious bright and dark stripes appear at the position of the light exiting region 262. The light emitted from the light guide plate 26 is relatively uniform.

Further, in the first embodiment, the second reflective structure 281 of the reflective structure 28 surrounds a portion of the light source 27 and the light guide strip 29, and the reflective structure 28 simultaneously functions as a light source reflector. In addition, when the refractive index of the light guiding strip 29 is greater than the refractive index of the light guide plate 26, according to the principle of refraction, the angle of the light entering the light guide plate 26 after being refracted through the intersection surface of the light incident surface 296 and the light incident surface 261 is relatively diffusion. The backlight module 1 is suitable for supplying light to the liquid crystal panel 22 having a large area but not requiring high brightness. When the refractive index of the light guiding strip 29 is smaller than the refractive index of the light guide plate 26, according to the principle of refraction, the angle of light entering the light guide plate 26 after being refracted through the intersection surface of the light incident surface 296 and the light incident surface 261 is concentrated. The backlight module 1 is suitable for supplying light to the liquid crystal panel 22 having a small area and requiring high light output brightness.

Please refer to FIG. 7 , which is a cross-sectional view showing the assembled backlight module 33 of the second embodiment of the liquid crystal display device of the present invention. The difference between the present embodiment and the first embodiment is that the point light source 372 of the light source 37 is a side-light source, and the circuit board 371 is located on a side of the point source 372 away from the light guide plate 36 and covers the second connection of the light guide bar 39. The fourth reflecting portion 377 of the reflecting structure 38 is separated from the other three reflecting portions of the reflecting structure 38 and disposed on the surface of the second connecting surface 392 of the circuit board 371 facing the light guiding strip 39. At the time of assembly, the light-emitting surface 373 of the point light source 372 faces the light-incident surface 397 of the light bar 39, and the circuit board 371 covers the point light source 372 and the light-guiding strip 39. The fourth reflecting portion 377 covers the second connecting surface 392.

Please refer to FIG. 8 , which is a cross-sectional view of the backlight module 43 of the third embodiment of the liquid crystal display device of the present invention after assembly. The third embodiment is different from the first embodiment in that the second reflecting portion and the second reflecting structure of the first reflecting structure of the reflective structure are disposed on the plastic frame 45. Specifically, the plastic frame 45 faces the side wall 451 of the optical film group 44, the light guide plate 46, the light source 47, the first reflecting portion 48, and the light guiding strip 49, and the supporting plate 452 faces the light source 47 and guides the light. The strip 49 and the light guide plate 46 are all provided with a reflective material, or the position itself is formed of a reflective material, such as a white plastic frame. Further, the second reflective structure of the reflective structure and the second reflective portion of the first reflective structure may be replaced. In addition, a third connecting surface 497 is further included between the first connecting surface 491 of the light guiding strip 49 and the second connecting surface 492. The third connecting surface 497 has a flat surface, as shown in FIG. 8 , and may also be an arc. surface. At the same time, the connection between the support plate 452 of the plastic frame 45 and the side wall 451 is disposed in a shape that is in contact with the third connection surface 497.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be included in the following claims.

2. . . Liquid crystal display device

twenty two. . . LCD panel

23, 33, 43. . . Backlight module

25, 45. . . Plastic frame

24, 44. . . Optical film set

26, 36, 46. . . Light guide

27, 37, 47. . . light source

28, 38. . . Reflective structure

29, 39, 49. . . Light guide strip

263. . . Bottom

265. . . side

262. . . Light exit area

261. . . Light entering area

260. . . Top surface

266. . . First side

251, 451. . . Side wall

252, 452. . . Support plate

297, 397. . . Glossy surface

296. . . Glossy surface

291, 491. . . First connection surface

292, 392, 492. . . Second connection surface

497. . . Third connection surface

271, 371. . . Circuit board

272, 372. . . point Light

273, 373. . . Luminous surface

283. . . First reflective structure

281. . . Second reflective structure

280. . . Containing space

288, 48. . . First reflection

282. . . Second reflection

285, 385. . . Third reflection

286. . . Fourth reflection

377. . . Fourth reflection

FIG. 1 is a schematic diagram of a backlight module in the prior art.

2 is a perspective exploded view of an embodiment of a liquid crystal display device of the present invention.

3 is a perspective view of a light guide plate of the liquid crystal display device of FIG. 2.

4 is a perspective view showing a light guiding strip, a light source, and a reflecting structure of the liquid crystal display device of FIG. 2.

FIG. 5 is a schematic view showing the assembly of the backlight module of FIG. 2.

Figure 6 is a schematic cross-sectional view taken along line VI-VI of Figure 5.

Fig. 7 is a cross-sectional view showing the assembly of the backlight module of the second embodiment of the liquid crystal display device of the present invention, the cutting position of which is the same as the cutting position in Fig. 5 shown in Fig. 6, and the liquid crystal panel is omitted.

8 is a cross-sectional view of the backlight module of the third embodiment of the liquid crystal display device of the present invention after assembly, and the cutting position is the same as the cutting position in FIG. 5 shown in FIG. 6, and the liquid crystal panel is omitted.

twenty three. . . Backlight module

25. . . Plastic frame

twenty four. . . Optical film set

27. . . light source

29. . . Light guide strip

263. . . Bottom

262. . . Light exit area

261. . . Light entering area

266. . . First side

252. . . Support plate

297. . . Glossy surface

296. . . Glossy surface

291. . . First connection surface

271. . . Circuit board

272. . . point Light

273. . . Luminous surface

283. . . First reflective structure

282. . . Second reflection

285. . . Third reflection

286. . . Fourth reflection

Claims (10)

A backlight module includes a point light source, a light guide plate, and a reflective structure, the light guide plate includes a top surface, a bottom surface opposite to the top surface, and a first side surface on the side of the light guide plate connecting the top surface and the bottom surface; The top surface of the light guide plate includes a light incident region and a light exit region. The light incident region is located at an end of the top surface adjacent to the first side surface. The backlight module further includes a light guide strip. The strip includes a light incident surface, a light exit surface disposed adjacent to the light incident surface, and a connection surface connected to the light incident surface and the light exit surface, and the light incident surface of the light guide strip is disposed opposite to the point light source to receive the point light source. The light emitting surface of the light guiding strip is disposed opposite to the light incident region of the light guiding plate to transmit the light to the light guiding plate. The reflective structure comprises a first reflective structure and a second reflective structure, and the first reflective structure covers a portion of the light guide plate, the second reflective structure covers a portion of the light guide strip, and the light generated by the point light source enters the light guide strip via the light incident surface of the light guide strip and changes the travel path via the reflection of the second reflective structure. The emitted light from the light emitting surface of the guide bar; the light from the exit surface of the light guide plate through the interior of the incident light into the region, and then by the reflective structure of the first light reflected from the region of the exit of the guide plate. The backlight module of claim 1, wherein the first reflective structure and the second reflective structure are one-piece components. The backlight module of claim 1, wherein the backlight module comprises a plastic frame, the plastic frame houses the light guide plate, the point light source and the light guiding strip, and the plastic frame faces the light guiding strip The connecting surface and the first side surface are provided with the first reflective structure and a portion of the second reflective structure. The backlight module of claim 3, wherein the plastic frame is a hollow frame, and includes a plurality of side walls and a support plate extending from an inner side of the side wall toward a center of the plastic frame, the support plate being located at the support The side wall of the same side of the board forms a receiving space for receiving the light guide plate, the point light source and the light guide strip. The backlight module further includes an optical film set disposed on a side of the light exiting area of the light guide plate. The backlight module of claim 1, wherein the point light source is disposed on a circuit board, the circuit board supplies power to the point light source, and the point light source is disposed between the light guide strip and the circuit board. The point source has a light emitting surface that faces away from the connection position of the point source and the circuit board. The backlight module of claim 1, wherein the light guiding strip comprises a first connecting surface disposed opposite to the light incident surface and a second connecting surface disposed opposite to the light emitting surface, the first reflective structure comprising Covering a first reflecting portion of the bottom surface of the light guide plate and a second reflecting portion covering the first side surface of the light guiding plate, the second reflecting structure includes a third reflecting portion covering the first connecting surface of the light guiding strip and a second covering portion of the light guiding strip a fourth reflecting portion of the connecting surface, one end of the second reflecting portion is connected to the first reflecting portion, and the opposite end is connected to the third reflecting portion, and one end of the third reflecting portion is connected to the second reflecting portion, and opposite One end is connected to the fourth reflecting portion, and one end of the fourth reflecting portion is connected to the third reflecting portion, and the opposite end is a free end, and the second reflecting portion is coplanar with the third reflecting portion. The backlight module of claim 6, wherein the point light source is disposed on a circuit board, and the circuit board supplies power to the point light source, the circuit board is located on a side of the point light source remote from the light guide plate and covers the The second connecting surface of the light source and the light guiding strip, the fourth reflecting portion of the reflective structure is disposed on a surface of the second connecting surface of the circuit board facing the light guiding strip, and the point light source is a side light emitting point light source. The backlight module of claim 7, wherein the light guide bar has a refractive index greater than a refractive index of the light guide plate. The backlight module of claim 6, wherein the second reflecting portion and the third reflecting portion are coplanar and perpendicular to the first reflecting portion, and the fourth reflecting portion is parallel to the first reflecting portion. A liquid crystal display device comprising a liquid crystal panel and a backlight module adjacent to the liquid crystal panel and providing a light source for the liquid crystal panel, wherein the backlight module is according to any one of claims 1 to 9. Backlight module.