CN106842701B

CN106842701B - Backlight module and liquid crystal display

Info

Publication number: CN106842701B
Application number: CN201710017091.3A
Authority: CN
Inventors: 樊勇
Original assignee: Shenzhen China Star Optoelectronics Technology Co Ltd
Current assignee: TCL Huaxing Photoelectric Technology Co Ltd
Priority date: 2017-01-11
Filing date: 2017-01-11
Publication date: 2020-05-19
Anticipated expiration: 2037-01-11
Also published as: CN106842701A

Abstract

The invention relates to the technical field of liquid crystal display, in particular to a backlight module and a liquid crystal display. The backlight module provided by the invention comprises the following components in sequence from bottom to top: printed circuit board, reflector plate, LED light source, diffuser plate, orientation at the diffuser plate around the projection of LED light source on going into the plain noodles of LED light source is provided with first bump, and first bump can be with the LED light source the regional diffusion of reflection of illuminating on the diffuser plate, eliminates the projection dark space, prevents the light source gathering for the distribution of light emitting area is more even on the diffuser plate, simultaneously, can carry out the independent control to the LED light source, and better realization local accuse light, thereby promote the display quality of high dynamic contrast image. The reflective sheet can reflect the leaked light again to irradiate the light onto the diffusion plate again, so that the utilization rate of the light source is improved, the light mixing distance is increased, and the thin design of the liquid crystal display is facilitated.

Description

Backlight module and liquid crystal display

Technical Field

The invention relates to the technical field of liquid crystal display, in particular to a backlight module and a liquid crystal display.

Background

At present, the application permeability of the LED as a backlight source in the field of liquid crystal panel display already exceeds 90%. The backlight module mainly comprises an edge-in type LED backlight and a direct-down type LED backlight, wherein an LED light source is arranged on the side face of the light guide plate, light emitted by the LED enters the light guide plate through coupling, and is guided out through reflection and scattering of the reflector plate and the mesh points. The direct-type LED backlight can more accurately represent images and exhibit excellent color and contrast effects, and thus is becoming the mainstream trend of the market.

Direct type LED backlight unit generally includes LCD display screen, diffuser plate and PCB board, is equipped with the LED light source after a plurality of encapsulation on the PCB board, and after the LED light source sent light, light became even, unanimous behind the diffuser plate, then evenly shines on the LCD display screen to the realization carries out the effect of throwing light on to liquid crystal display device.

Direct-type backlight modules are widely used in large-size displays. The common direct type backlight module mostly adopts a plurality of closely arranged LEDs or LEDs with lenses as light sources, the light rays of the two light sources are not limited to be transmitted in a light mixing cavity of the backlight module, and a part of the light rays are often transmitted to other areas directly or through reflection to influence the light emitting effect; meanwhile, no matter the scheme of arranging a plurality of LEDs or the scheme of adopting a secondary lens, light projection is circular, the projection of adjacent LEDs on the diffusion plate can not be fused, and the phenomenon of uneven brightness often appears on the diffusion plate.

The four-side light-emitting LED is an LED formed by coating a fluorescent powder colloid layer and a white reflective colloid layer on a blue light flip chip, the structural schematic diagram of the four-side light-emitting LED is shown in figure 1, the fluorescent powder colloid layer 13 and the white reflective colloid 14 are sequentially coated on the blue light LED chip 12 of the flip structure, and the four-side light-emitting LED is connected with a corresponding control signal through a metal electrode 11 arranged at the bottom of the chip 12 so as to emit light. The LED has the advantages of small size and high driving power, and because the fluorescent powder colloid layer 13 and the white reflective glue 14 are both rectangular, the light emitting surface of the LED is also rectangular, and therefore, the light projection emitted by the four-side light emitting LED is also rectangular, so that the LED is more suitable for a common rectangular display.

How to apply the four-side light-emitting LED to the local dimming liquid crystal display and realize the backlight thickness thinner than the existing local dimming backlight module becomes the problem to be solved by using the four-side light-emitting LED as the backlight.

Disclosure of Invention

In order to apply the four-side light-emitting LED to the backlight module so as to realize better local dimming effect, the invention provides the backlight module and a liquid crystal display comprising the same.

The invention provides a backlight module, comprising: a printed circuit board; the reflecting sheet is arranged on the first surface of the printed circuit board, and a hollow part is arranged on the reflecting sheet; the LED light source is fixedly connected to the first surface of the printed circuit board through the hollow part of the reflector plate; the diffuser plate, the diffuser plate sets up LED light source reverse in one side of printed circuit board, be provided with first bump on going into the plain noodles of diffuser plate, first bump is arranged the LED light source is in go into around the projection on the plain noodles, it is for to go into the plain noodles the orientation of diffuser plate the one side of LED light source.

The backlight module of this kind of setting, after the light that the LED light source sent shines on the income plain noodles of diffuser plate, takes place the reflection diffusion under the effect of first bump, has eliminated the projection dark space, prevents the light source gathering for the luminous zone light distribution is more even on the diffuser plate, simultaneously, can carry out the independent control to the LED light source, and the local accuse of better realization is light, thereby promotes the display quality of high dynamic contrast image. Furthermore, the light rays which are not irradiated on the diffusion plate can be reflected again by the reflection sheet, so that the light rays are irradiated on the diffusion plate again, the utilization rate of a light source is improved, the light mixing distance is increased, and the thin design of the liquid crystal display is favorably realized.

As a further improvement of the backlight module provided by the present invention, the LED light sources are four-side light emitting LEDs, the first bumps are arranged around a first projection in a matrix form, and the first projection is a projection of the LED light sources on the light incident surface.

The light-emitting surfaces of the four-side light-emitting LEDs form a rectangle, so that the projection of the four-side light-emitting LEDs on the light-in surface of the diffusion plate is also a rectangular light-emitting area, the first convex points arranged in a matrix form enable light rays emitted by the LED light source to be displayed in the rectangular light-emitting area after passing through the diffusion plate, and the plurality of rectangular light-emitting areas can be seamlessly spliced into a whole light-emitting area corresponding to the rectangular display, so that the light rays of the display are more uniform, and the defect caused by poor light ray. Meanwhile, because the liquid crystal display generally adopts the matrix light control, the rectangular light emitting area can enable the area light control of the liquid crystal display to be more accurate.

As a further improvement of the backlight module proposed by the present invention, an area ratio of the first salient points decreases from the first projection to the outside, and the area ratio is an area ratio of the first salient points in a unit area.

Light is dense near the LED light source, so that the dense light can be reflected and diffused by more first salient points, the light is gradually reduced far away from the LED light source, the area ratio of the corresponding first salient points is correspondingly reduced, the arrangement mode of changing the area ratio of the first salient points along with the light density degree can fully reflect and diffuse the light, the unnecessary first salient points are reduced, the process difficulty is reduced, and the production efficiency is improved.

As a further improvement to the first salient point, the maximum diameter of the first salient point on the light incident surface is less than 2 mm. The first salient points with the size cannot cause shadow on the light emergent surface of the diffusion plate under the irradiation of the light source, and the dark space defect caused by the first salient points is avoided.

As a further improvement of the backlight module provided by the present invention, a light-emitting surface of the diffusion plate is provided with a second bump, and the light-emitting surface is a surface of the diffusion plate deviating from the LED light source. The setting of second bump is favorable to being sent out the light mixed light in the whole light-emitting surface that the region concatenation formed by a plurality of LED light sources, has further increased the mixed light distance for light distribution is more even, has further improved the luminance of display.

As a further improvement of the backlight module provided by the present invention, the backlight module further includes an optical film, and the optical film is disposed on a side of the diffusion plate facing away from the LED light source. The optical film can enable light emitted by the light emitting surface of the diffusion plate to be efficiently irradiated onto the LCD screen, and particularly when the optical film is a prism film, the light mixing distance is increased, and the brightness and the uniformity of the LCD screen are further improved.

The invention also provides a liquid crystal display, which comprises the backlight module, wherein the backlight module comprises: a printed circuit board; the reflecting sheet is arranged on the first surface of the printed circuit board, and a hollow part is arranged on the reflecting sheet; the LED light source is fixedly connected to the printed circuit board through the hollow part of the reflector plate; the diffuser plate, the diffuser plate sets up LED light source reverse in one side of printed circuit board, be provided with first bump on going into the plain noodles of diffuser plate, first bump is arranged the LED light source is in go into around the projection on the plain noodles, it is for to go into the plain noodles the orientation of diffuser plate the one side of LED light source.

As a further improvement of the liquid crystal display of the present invention, the LED light sources are four-side light emitting LEDs, the first bumps are arranged around a first projection in a matrix form, and the first projection is a projection of the LED light sources on the light incident surface.

In summary, the backlight module provided by the invention prevents light from being gathered at one position under the action of the first salient points, enlarges the light emitting area on the diffusion plate, makes the light distribution on the diffusion plate more uniform, and simultaneously can control the LED light sources individually, thereby better realizing local light control, and further improving the display quality of high dynamic contrast images. Meanwhile, the light rays which are not irradiated on the diffusion plate can be reflected again by the reflection sheet, so that the light rays are irradiated on the diffusion plate again, and the utilization rate of the light source is improved. The arrangement of the second salient points and the optical film is not only beneficial to light mixing in the whole light emitting surface formed by splicing the light emitting areas of the plurality of LED light sources, but also enables light emitted by the light emitting area of the diffusion plate to efficiently irradiate the LCD screen, so that the light mixing distance is increased, the light distribution is more uniform, the brightness of the display is improved, and the thinning design of the liquid crystal display is beneficial to realization.

Drawings

The invention will be described in more detail hereinafter on the basis of embodiments and with reference to the accompanying drawings. Wherein:

FIG. 1 is a schematic diagram of a four-sided LED in the prior art;

fig. 2 is a schematic structural diagram of a backlight module according to the present invention;

FIG. 3 is a schematic view of a first bump arrangement on a diffuser plate of a backlight module according to the present invention;

fig. 4 is an illuminated area of a four-sided light emitting LED on a diffuser plate.

In the drawings, like parts are provided with like reference numerals. The drawings are not to scale.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings, wherein the following descriptions "upper", "lower", "left" and "right" are relative to the illustrated direction, and should not be construed as limiting the present invention.

Fig. 1 is a schematic structural diagram of a four-side light-emitting LED in the prior art, generally, the four-side light-emitting LED is connected to a printed circuit board through a metal electrode 11, and the operating mode of the four-side light-emitting LED is controlled through the printed circuit board.

Fig. 2 is a schematic structural diagram of a backlight module 20 according to the present invention, and as can be seen from fig. 2, the backlight module sequentially includes a printed circuit board 21, a reflector 22, an LED light source 23 and a diffuser plate 24 from bottom to top, wherein the reflector 22 is disposed on a first surface 211 of the printed circuit board 21, the reflector 22 is a mirror-like reflector, so that the reflector 22 can well reflect incident light, the reflector 22 can be disposed on the first surface 211 of the printed circuit board 21 by means of pasting or other means, and preferably, the reflector 22 is fully covered on the first surface 211 of the printed circuit board 21. The corresponding position of the reflector plate 22 is provided with a hollow part, the LED light source 23 is fixedly connected to the printed circuit board 21 through the hollow part of the reflector plate 22, and the working mode of the LED light source 23 is controlled through the printed circuit board 21. The surface of the diffusion plate 24 facing the LED light source 23, i.e. the light incident surface 241, is provided with first bumps 242, the reflectivity of the first bumps 242 is greater than 80%, and the transmittance is less than 20%, so that the first bumps 242 can reflect and scatter the incident light well, and preferably, the first bumps 242 are disposed around the projection of the LED light source 23 on the light incident surface 241. The first protruding points 242 reflect and diffuse the light emitted from the LED light sources 23 onto the diffusion plate 24, so as to not only eliminate the projection dark area, but also avoid the light from being gathered, so that the brightness of the light emitting area is more uniform, and the distance d1 between the light incident surface 241 of the diffusion plate 24 and the surface of the LED light sources 23 facing the diffusion plate 24 is set according to the distance d2 between the LED light sources 23. The plurality of light emitting regions formed by the plurality of LED light sources 23 on the diffusion plate 24 constitute a diffusion plate that emits light as a whole, thereby providing a desired luminance to the liquid crystal display. When the single LED light source 23 is controlled individually, local light control can be better achieved, thereby improving the display quality of high dynamic contrast images. The reflector 22 can reflect the light leaked from the LED light source 23 to the diffuser 24 again, so as to further improve the utilization rate of the light source, and the arrangement of the first bumps 242 and the reflector 22 increases the light mixing distance, reduces the thickness of the backlight module, and is beneficial to the realization of the thin design of the liquid crystal display.

The LED light source 23 may be LED light sources with various shapes, preferably, the LED light source 23 is a four-side light emitting LED, so that the light emitting surface of the LED light source 23 is rectangular, the illuminated area of the LED light source 23 on the light incident surface 241 of the diffusion plate 24 is as shown in fig. 4, as can be seen from fig. 4, the center of the illuminated area is a first projection 243 of the LED light source 23 on the light incident surface 241, the inside of the first projection 243 is dark, the outside of the first projection 243 is a highlight area formed by the LED light source 23, and the brightness of the highlight area is not uniform, and the brightness gradually decreases at a position far away from the first projection 243, in order to eliminate the inner dark area of the first projection 243 on the diffusion plate 24 and simultaneously make the brightness more uniform, as shown in fig. 3, preferably, the first protrusions 242 are arranged in a matrix around the first projection 243, the light of the illuminated area is reflected and scattered by the first protrusions 242, which not only can eliminate the dark area inside, and the brightness of the light emitting area generated by the LED light sources 23 on the diffusion plate 24 is more uniform, at this time, the distance d1 between the light incident surface 241 of the diffusion plate 24 and one surface of the LED light sources 23 facing the diffusion plate 24 is determined according to the distance d2 between the two adjacent LED light sources 23, so that the whole light emitting area corresponding to the rectangular display can be seamlessly spliced into a plurality of rectangular light emitting areas, which is optimal, thereby the light of the display is more uniform, and the defect caused by poor light splicing is avoided. Meanwhile, because the liquid crystal display generally adopts the matrix light control, the rectangular light emitting area can enable the area light control of the liquid crystal display to be more accurate.

When the first bumps 242 are disposed, since the light is more concentrated closer to the first projection 243, the area of the first bumps 242 per unit area is gradually decreased from the first projection 243 outwards, that is, the area ratio of the first bumps 242 is gradually decreased from the first projection 243 outwards, so that the light can be better reflected and diffused by setting the area ratio of the first bumps 242 according to the density of the light, and the brightness of the light emitting area on the diffusion plate 24 is more uniform. In order to avoid the first bumps 242 from forming a black shadow on the light exit surface of the diffuser plate 24, the maximum diameter of the first bumps 242 on the light entrance surface 241 is preferably less than 2mm, that is, the maximum diameter of the projection of each first bump 242 on the light entrance surface 241 of the diffuser plate 24 is less than 2mm, so as to avoid the brightness defect caused by the first bumps 242.

Preferably, the second bumps 245 are disposed on a surface, which is away from the LED light sources 23, of the diffusion plate 24, that is, the light emitting surface 244, and preferably, the second bumps 245 are uniformly disposed on the light emitting surface 244, so that light mixing in the whole light emitting surface formed by splicing the light emitting regions of the LED light sources is facilitated, the light mixing distance is further increased, the light distribution is more uniform, and the brightness of the display is improved.

In a preferred embodiment, the backlight module of the present invention further includes an optical film 25 disposed on a side of the diffusion plate 24 away from the LED light sources 23, where the optical film 25 can make the light emitted from the light emitting surface 244 of the diffusion plate 24 irradiate the liquid crystal panel with high efficiency, and especially when the optical film 25 is a prism film, the light mixing distance is further increased, and the brightness and uniformity of the liquid crystal panel are improved.

The liquid crystal display comprises the backlight module 20 and the liquid crystal screen, wherein the liquid crystal screen is arranged on one side, away from the diffusion plate 24, of the optical film 25 of the backlight module 20, and light emitted from the light emitting surface of the diffusion plate enters the liquid crystal screen through the optical film 25 to provide a high-brightness and uniform light source for the liquid crystal display.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims

1. A backlight module, comprising:

a printed circuit board;

the reflecting sheet is arranged on the first surface of the printed circuit board, and a hollow part is arranged on the reflecting sheet;

the LED light sources are fixedly connected to the printed circuit board through the hollow parts of the reflector plate and can be controlled independently;

the diffuser plate, the diffuser plate sets up LED light source reverse in one side of printed circuit board, be provided with first bump on going into the plain noodles of diffuser plate, every LED light source is in all arranged a plurality of first bumps around going into the projection on the plain noodles, it is for to go into the plain noodles the orientation of diffuser plate the one side of LED light source.

2. The backlight module according to claim 1, wherein the LED light source is a four-sided light emitting LED.

3. The backlight module according to claim 2, wherein the plurality of first protrusions around each first projection are arranged in a matrix around each first projection, and the first projections are projections of the LED light sources on the light incident surface.

4. The backlight module as claimed in claim 3, wherein the area ratio of the first salient points around each first projection decreases from the first projection to the outside, and the area ratio is the area ratio of the first salient points per unit area.

5. The backlight module as claimed in any one of claims 1 to 4, wherein the maximum diameter of the first salient points on the light incident surface is less than 2 mm.

6. The backlight module as claimed in any one of claims 1 to 4, wherein a second bump is disposed on a light-emitting surface of the diffuser plate, the light-emitting surface being a surface of the diffuser plate facing away from the LED light source.

7. The backlight module according to claim 6, further comprising an optical film disposed on a side of the diffuser plate facing away from the LED light sources.

8. A backlight module according to claim 7, wherein the optical film is a prismatic film.

9. A liquid crystal display comprising the backlight module of any one of claims 1 to 8, the backlight module comprising:

a printed circuit board;

10. The lcd of claim 9, wherein the LED light sources are four-side emitting LEDs, and the plurality of first bumps surrounding each first projection are arranged in a matrix around each first projection, the first projection being a projection of the LED light sources on the light incident surface.