TWI421589B - Backlight module and liquid crystal display device using same - Google Patents

Description

Backlight module and liquid crystal display device using the same

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

In recent years, liquid crystal display devices have a small size and a small footprint. The advantages of small radiation and gradually occupy the mainstream of display products. In the liquid crystal display device, the liquid crystal panel itself does not emit light, but the backlight module provides planar light with uniform illumination.

The backlight module generally includes an optical film set, a light guide plate, a light source, and a light source reflection cover. The light guide plate includes a light exit surface and a light incident surface adjacent to the light exit surface. The light source reflector covers the light source and is placed on the light incident surface side of the light guide plate, and the edge of the light source reflector covers the edge of the light exit surface of the light guide plate. The optical film group is attached to the light-emitting surface side of the light guide plate.

After the light emitted by the light-emitting diode passes through the light guide plate, most of the light is emitted through the light-emitting surface of the light guide plate. The backlight module emits uniform planar light by emitting the backlight module after multiple diffusion and convergence of the optical film. However, each component material of the backlight module has a certain tolerance during fabrication, so that a certain gap is left between the edge of the optical film group and the edge of the light source reflector, and the light emitted by the light exit surface of the light guide plate is The gap is emitted without diffusing and concentrating the light through the optical film group, which causes the gap of the backlight module to be brighter, thereby affecting the uniformity and quality of the light output of the backlight module.

In view of this, the present invention provides a backlight module with relatively uniform light output.

In addition, a liquid crystal display device using the above backlight module is provided.

A backlight module includes an optical film, a light guide plate, a light source, and a light source shielding cover. The light guide plate includes a light emitting surface, a light incident surface and a bottom surface, and the bottom surface is opposite to the light emitting surface, and the light incident surface is adjacent to the bottom surface The optical film is disposed on a side of the light-emitting surface, and the light source is disposed on a side of the light-incident surface. The light-guiding plate further includes an inwardly recessed receiving portion on a side of the light-emitting surface adjacent to the light-incident surface, the receiving portion receiving Part of the light source shield, the edge of the optical film covers the edge of the light source shield.

A liquid crystal display device includes a liquid crystal display panel and a backlight module. The liquid crystal display panel and the backlight module are stacked. The backlight module includes an optical film, a light guide plate, a light source and a light source shielding cover. The light plate comprises a light-emitting surface, a light-incident surface and a bottom surface, wherein the bottom surface is opposite to the light-emitting surface, the light-incident surface is disposed adjacent to the bottom surface, the optical film is disposed on the light-emitting surface side, and the light source is disposed on the light-incident surface The side of the light guide plate adjacent to the light incident surface further includes an inwardly recessed receiving portion, the receiving portion receiving a portion of the light source shielding cover, and the edge of the optical film covering the edge of the light source shielding cover.

Compared with the prior art, an accommodating portion is disposed between the light incident surface and the light emitting surface of the light guide plate in the backlight module, and the accommodating portion receives the light source shielding cover, so that the light source shielding cover and the optical film are not in the same plane, and The optical film covers the edge of the light source cover, so that all the light emitted through the backlight module is concentrated and diffused through the optical film group, and the backlight module and the liquid crystal display device using the backlight module emit light uniformly.

1 is a perspective exploded view of a first embodiment of a liquid crystal display device of the present invention, FIG. 2 is a partial assembly diagram of the liquid crystal display device shown in FIG. 1, and FIG. 3 is a cross-sectional view of FIG. Schematic diagram of the section at -III.

The liquid crystal display device 100 includes a liquid crystal display panel 1 , a light shielding tape 3 , and a backlight module 4 . The liquid crystal display panel 1 and the backlight module 4 are stacked. The light-shielding tape 3 is attached to the liquid crystal panel 1 and the backlight module 4, and the liquid crystal display panel 1 and the backlight module 4 are fixed in position.

The backlight module 4 includes an optical film group 41, a light source group 42, a hollow plastic frame 43, a light guide plate 44, and a reflection sheet 45. The plastic frame 43 includes end to end Four side walls (not shown). The light source 42 includes a two-point light source 421 and a strip-shaped flexible printed circuit board 422 for driving the light source 421 to emit light. The two-point light source 421 is disposed on the strip-shaped flexible printed circuit board 422, which is preferably a light-emitting diode light source. Other light sources may be used as needed, and the number of light sources may be one or more as needed. The point light source 421 includes a light emitting surface (not labeled) parallel to the flexible printed circuit board 422. The distance from the light emitting surface to the printed circuit board 422 is the height of the point light source 421. The light emitting surface is substantially rectangular and includes two opposite lengths. The opposite side of the two sides.

The light guide plate 44 includes a bottom surface 441, a light incident surface 442 adjacent to the bottom surface 441, and a light exit surface 443 opposite to the bottom surface 441. The area of the light-emitting surface 443 matches the area of the display area of the liquid crystal display panel 1. The light guide plate 44 is recessed inwardly on a side of the light exit surface 443 adjacent to the light incident surface to form a receiving portion (not labeled). Preferably, the receiving portion includes a bearing surface 444 and a connecting surface 445 perpendicular to the bearing surface 444. The bearing surface 444 is perpendicular to and adjacent to the light incident surface 442 . The connecting surface 445 is perpendicular to the bearing surface 444 and parallel to the light incident surface 442 . The light incident surface 442, the bearing surface 444, the connecting surface 445 and the light exiting surface 443 are sequentially connected to form a two-stage stepped structure. The height of the connecting surface 445 is the same as or slightly higher than the thickness of the reflecting sheet 45. The height of the light incident surface 442 is the same as or slightly higher than the width of the light emitting surface of the light source 421. The sum of the height of the light incident surface 442 and the height of the connecting surface 445 is equal to the thickness of the light guide plate 44, that is, the distance from the bottom surface 441 of the light guide plate 44 to the light exit surface 443. The light guide plate 44 is usually made of a resin material having a high transmittance. The bearing surface 444 has a light diffusing function, which can be formed by disposing a polymer compound material diffusion particle on the bearing surface 444. Now, the flatness of the bearing surface 444 is changed either by providing a microstructure on the bearing surface 444 or the like.

The optical film group 41 includes optical elements such as a diffusion sheet and a prism sheet. The diffusion sheet and the prism sheet are sequentially laminated on the light-emitting surface 443 of the light guide plate 44. Therefore, the light emitted through the light-emitting surface 443 is sequentially collected and diffused by the diffusion sheet and the prism sheet, and then emitted to the backlight module 4, so that the light emitted by the backlight module 4 is more uniform. The length of the optical film group 41 is greater than the length of the light-emitting surface 443 of the light guide plate 44, and the elongated portion covers at least a portion of the bearing surface 444 of the light guide plate.

The reflective sheet 45 includes a body (not labeled) and an extension 452. The reflection sheet 45 is longer than the length of the bottom surface 441 of the light guide plate 44 to form the extension portion 452 at the growing portion. A flexible printed circuit board 422 of the light source 42 is disposed on the extension 452 to secure the light source 42 to the reflective sheet 45. The extending portion 452 of the reflective sheet 45 includes three first connecting portions 4521, a light source setting portion 4522, and a light source shielding cover 4523. The first connecting portion 4521 is connected to the main body of the reflection sheet 45. The width of the first connecting portion 4521 (the distance between the common side of the first connecting portion 4521 and the light source setting portion4522 to the common side of the first connecting portion 4521 and the main body) is greater than the height of the point light source 421 and the flexible printed circuit board The sum of the thicknesses of 422. The light source setting portion 4522 has an area equal to or larger than the area of the flexible printed circuit board 422. The width of the light source shielding cover 4523 (the distance from the common side of the light source shielding cover 4523 and the light source setting portion 4522 to the other side opposite to the common side) is larger than the width of the first connecting portion 4521.

The bottom surface 441 of the light guide plate 44 is disposed on the main body of the light guide plate 45. The extending portion 452 of the reflective sheet 45 is bent toward the light guide plate 44 and partially covers the receiving portion of the light guide plate 44. Wherein the light source setting part The light source 421 is disposed between the light source setting portion 4522 and the light incident surface 442 of the light guide plate 44. The light source 421 is disposed opposite to the light incident surface 442 of the light guide plate 44. The light source shielding cover 4523 is bent relative to the light source setting portion 4522, and the light source shielding cover 4523 is partially overlapped with the receiving portion of the light guiding plate 44, that is, the bearing surface 444. The light source installation portion 4522 is directly incident on the light incident surface 442 of the light guide plate 44. The light source 42 is housed in the accommodating space formed by the first connection portion 4521, the light source installation portion 4522, the light source shielding cover 4523, and the light incident surface 442 of the light guide plate 44. . The point light source 421 is directly incident on the light incident surface 442 of the light guide plate 44, and the light emitted from the point light source 421 directly enters the inside of the light guide plate 44. The optical film group 41 is disposed on one side of the light-emitting surface 443 of the light guide plate 44. The elongated portion of the optical film set 41 covers the edge of the light source shield 4523 of the reflective sheet 45, so that voids due to design tolerances are covered by the optical film set 41. The plastic frame 43 houses the optical film group 41, the light source group 42, the light guide plate 44, and the reflection sheet 45, thereby completing the assembly of the backlight module 4.

The light emitted from the point light source 421 passes through the light incident surface 442 of the light guide plate 44 and propagates inside the light guide plate 44. Most of the light is emitted through the light exit surface 443 of the light guide plate 44; the other portion of the light passes through the reflection sheet. The reflection of 45 is propagated in the light guide plate 44, and finally is emitted through the light exit surface 443 of the light guide plate 44. The light emitted from the bearing surface 444 is divided into two parts, and a part of the light passes through the diffusion particle or the diffusion surface. The light source shielding cover 4523 of the 45 is reflected back to the light guiding plate 44 and continues to propagate in the light guiding plate 44; the other portion is directed to the optical film group 41 through the diffusion particles or the diffusion surface, and the optical film group 41 passes through the optical film group 41. After the conversion, the backlight module 4 is emitted.

Therefore, between the light incident surface 442 of the light guide plate 44 and the light exit surface 443 The light source shielding cover 4523 for accommodating the reflection sheet is disposed so that the light source shielding cover 4523 of the reflection sheet is not on the same surface as the optical film 41, and the optical film 41 is extended to cover the light source covering the reflection sheet 45. The edge of the cover 4523. The light leaks from the edge of the light source shielding cover 4523 of the reflection sheet 45 to the gap of the connection surface 445 of the light guide plate 44, and is emitted after being diffused and concentrated by the optical film 41, and does not form a bright line locally. The uniformity of the light output of the backlight module 4 is improved, and since the light source shielding cover 4523 of the reflective sheet is not on the same surface as the optical film 41, the light output of the backlight module 4 is increased without increasing the thickness of the module. Evenness.

4 is a perspective exploded view of a liquid crystal display device according to a second embodiment of the present invention, and FIG. 5 is a partially assembled schematic view of the liquid crystal display device shown in FIG. Schematic diagram of the section. The difference between this embodiment and the first embodiment is that a side wall 731 is provided on one side wall of the plastic frame 73. The flexible printed circuit board 722 of the light source group 72 is free to pass through the strip-shaped through hole 731, which simultaneously serves as a light source shield. The point light source 721 is an edge-lit light. The extending portion 752 of the reflection sheet 75 can be bent to serve as a lamp reflector, and the point light source 721 is housed together with the light incident surface 742 of the light guide plate 74 and the flexible printed circuit board 722.

When assembled, the flexible printed circuit board 722 extends from the inner side of the plastic frame 73 through the strip-shaped through hole 731, and the plastic frame 73 is electrically connected to the external circuit; the bearing surface 744 of the light guide plate 74 is disposed adjacent to the flexible printed circuit board 722. And a double-sided tape 80 is disposed at the intersection of the flexible printed circuit board 722 and the bearing surface 744, thereby fixing the light source group 72. The light incident surface 742 is disposed adjacent to the point light source 721; the reflective sheet 75 is adjacent to the bottom surface of the light guide plate 74. The 741 is disposed such that the bottom surface 741 of the light guide plate 74 is attached to the region of the reflection sheet 75 having no extension portion 752. The flexible printed circuit board 722, the light incident surface 742, the reflective sheet 75 and the extending portion 752 form a receiving space for receiving the extending portion 752 of the reflecting sheet 75 in the direction of the light incident surface 742 of the light guide plate 74. The point light source 721 allows the light emitted from the point source 721 to directly enter the light guide plate 74.

The invention has other embodiments, such as the light source is a strip light source, the flexible printed circuit board is a lamp tube reflector, and the light source is a strip lamp tube, and the metal tube reflector cover with a U-shaped cross section is wrapped and fixed. The strip-shaped lamp, a side wall of the lamp reflector is used as a light source shield or the like instead of the light-shielding cover of the reflection sheet in the first embodiment.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100‧‧‧Liquid crystal display device

1‧‧‧LCD panel

3‧‧‧Lighting tape

4‧‧‧Backlight module

41‧‧‧Optical diaphragm group

42, 72‧‧‧Light source group

43, 73‧‧‧ plastic frame

44, 74‧‧‧Light guide plate

45, 75‧‧‧ reflection film

421, 721‧‧ ‧ point light source

422, 722‧‧‧Soft printed circuit boards

441, 741‧‧‧ bottom

442, 742‧‧‧ into the glossy

443‧‧‧Glossy

444, 744‧‧ ‧ bearing surface

445‧‧‧ Connection surface

452, 752‧‧‧ extensions

4521‧‧‧First connection

4522‧‧‧Light source setting department

4523‧‧‧Light source cover

731‧‧‧through hole

80‧‧‧Double-sided tape

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an exploded perspective view showing a first embodiment of a liquid crystal display device of the present invention.

2 is a partial assembly diagram of the liquid crystal display device shown in FIG. 1.

Figure 3 is a schematic cross-sectional view taken along line III-III of Figure 2.

Fig. 4 is an exploded perspective view showing a second embodiment of the liquid crystal display device of the present invention.

FIG. 5 is a partially assembled schematic view of the liquid crystal display device shown in FIG. 4. FIG.

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

100‧‧‧Liquid crystal display device

41‧‧‧Optical diaphragm group

44‧‧‧Light guide plate

45‧‧‧reflecting film

421‧‧‧ point light source

441‧‧‧ bottom

442‧‧‧Into the glossy surface

444‧‧‧ bearing surface

4522‧‧‧Light source setting department

4523‧‧‧Light source cover

Claims (16)

A backlight module includes an optical film, a light guide plate, a light source, and a light source shielding cover. The light guide plate includes a light emitting surface, a light incident surface and a bottom surface, and the bottom surface is opposite to the light emitting surface, and the light incident surface is opposite to the bottom surface Adjacently disposed, the optical film is disposed on a side of the light-emitting surface, and the light source is disposed on a side of the light-incident surface, wherein the light-guiding plate further includes an inwardly recessed receiving portion on a side of the light-emitting surface adjacent to the light-incident surface. The accommodating portion receives a part of the light source shielding cover, and the edge of the optical film covers the edge of the light source shielding cover. The accommodating portion includes a bearing surface and a connecting surface, and the light incident surface, the bearing surface, the connecting surface and the light emitting surface sequentially form a second step. Structure. The backlight module of claim 1, wherein the bearing surface is perpendicular to the connecting surface, the light incident surface is perpendicular to the bearing surface, and the light incident surface is parallel to the connecting surface. The backlight module of claim 1, wherein the bearing surface has a light diffusing function. The backlight module of claim 1, wherein the height of the connecting surface is not less than the thickness of the light source shielding cover. The backlight module of claim 1, wherein the light source shielding cover is a light source reflecting cover, and the light source reflecting cover and the light incident surface define a receiving space for receiving the light source. The backlight module of claim 1, wherein the light source shielding cover is a circuit board, and the light source is disposed on the circuit board. The backlight module of claim 6, wherein the backlight module further comprises a plastic frame for accommodating the optical film, the light guide plate, the light source, the circuit board and the light source shielding cover of the backlight module, the glue The frame includes four sidewalls connected in sequence, one of the sidewalls corresponding to the light incident surface of the light guide plate, and the sidewall includes a through hole for connecting the circuit board to the external circuit through the through hole. The backlight module of claim 1, wherein the backlight module further comprises a reflective sheet, the reflective sheet comprising a body and an extension. The bottom surface is disposed adjacent to the reflector body, and the edge of the extension portion is coupled to the bearing surface to serve as a light source shielding cover. The extending portion and the light incident surface define a receiving space for receiving the light source. A liquid crystal display device includes a liquid crystal display panel and a backlight module. The liquid crystal display panel and the backlight module are stacked. The backlight module includes an optical film, a light guide plate, a light source, and a light source shielding cover. The light guide plate The light emitting surface, the light incident surface and a bottom surface are disposed opposite to the light emitting surface, the light incident surface is disposed adjacent to the bottom surface, the optical film is disposed on the light emitting surface side, and the light source is disposed on the light incident surface a side, wherein the light guide plate further includes an inwardly recessed receiving portion on a side of the light emitting surface adjacent to the light incident surface, the receiving portion receiving a portion of the light source shielding cover, the edge of the optical film covering the edge of the light source shielding cover, the receiving portion The bearing surface and the connecting surface are included, and the light incident surface, the bearing surface, the connecting surface and the light emitting surface sequentially form a two-step structure. The liquid crystal display device according to claim 9, wherein the bearing surface is perpendicular to the connecting surface, the light incident surface is perpendicular to the bearing surface, and the light incident surface is parallel to the connecting surface. The liquid crystal display device of claim 9, wherein the bearing surface has a light diffusing function. The liquid crystal display device of claim 9, wherein the height of the connecting surface is not less than the thickness of the light source shielding cover. The liquid crystal display device of claim 9, wherein the light source shielding cover is a light source reflecting cover, and the light source reflecting cover and the light incident surface define a receiving space for receiving the light source. The liquid crystal display device of claim 9, wherein the light source shielding cover is a circuit board, and the light source is disposed on the circuit board. The liquid crystal display device of claim 14, wherein The backlight module further includes a plastic frame for accommodating the optical film, the light guide plate, the light source, the circuit board and the light source shielding cover of the backlight module, and the plastic frame includes four side walls sequentially connected, wherein one side wall corresponds to the light guide plate The light incident surface includes a shape of a through hole through which the circuit board is connected to an external circuit. The liquid crystal display device of claim 9, wherein the backlight module further comprises a reflective sheet, the reflective sheet comprises a main body and an extending portion, the bottom surface is disposed adjacent to the reflective sheet main body, and the extending portion is edged The receiving surface is connected to serve as a light source shielding cover, and the extending portion and the light incident surface define a receiving space for receiving the light source.