CN105223734A - A kind of backlight module for liquid crystal display - Google Patents

Abstract

The invention provides a backlight module for a liquid crystal display, comprising: the back plate comprises a reflector plate and an LED light source, and the LED light source is arranged above the reflector plate; a porous optical control film positioned above the back plate; and the composite diffusion plate, wherein the first diffusion layer comprises first diffusion particles, the transparent layer is positioned above the first diffusion layer, and the second diffusion layer is positioned above the transparent layer. The composite diffusion plate refracts, reflects and/or scatters light of the LED light source through the first diffusion layer and the second diffusion layer. Compared with the prior art, the composite diffusion plate is designed, the diffusion layers with the diffusion function are respectively arranged on the upper side and the lower side of the transparent layer, and the light emitted by the LED light source can be atomized by utilizing the diffusion layers, so that the obvious bright band and dark band distribution is avoided, and the bad situations such as point moire on a picture and the like are eliminated.

Description

A kind of backlight module for liquid crystal display

technical field

The invention relates to a liquid crystal display, in particular to a backlight module used for the liquid crystal display.

Background technique

A liquid crystal display (Liquid Crystal Display, LCD) is the most common display technology today. In liquid crystal displays, liquid crystal is a substance between solid and liquid, which cannot emit light by itself, and must rely on a backlight to achieve the display function. The performance of the backlight source will directly affect the image quality of the liquid crystal display, especially the brightness of the backlight source will directly affect the brightness of the surface of the liquid crystal display.

Generally speaking, the liquid crystal backlight system is mainly composed of a light source, a light guide plate, and various optical films. A backlight system with excellent performance often needs to have the characteristics of high brightness, long life, and uniform light emission. At present, there are mainly three types of backlights: electroluminescence (ElectroLuminescence, EL), cold cathode fluorescent lamp (Cold Cathode Fluorescent Lamp, CCFL) and light emitting diode (Light Emitting Diode, LED). two kinds. With the continuous development of liquid crystal modules in the direction of brighter, lighter and thinner, LED backlights have the potential to become the mainstream of current backlight development.

On the other hand, as the manufacturing technology of liquid crystal display devices becomes more and more mature, due to the increase of consumers' preferences and personalized demands, liquid crystal display devices are also gradually developing towards ultra-thinning. In order to achieve the purpose of ultra-thinning, the thickness of each component of the liquid crystal display device needs to be reduced, such as the display panel, the optical film and the backlight module. Since the backlight module needs light mixing space, its thickness is usually relatively large, so it has also become the main object of thickness reduction. A solution in the prior art is to arrange a plurality of LED light sources on the bottom plate of the direct-lit backlight module, and then arrange a reflective film above the LED light sources. There are multiple perforations on the reflective film, and the light emitted by the LED light source is reflected back and forth between the reflective film and the base plate, and then emitted through different perforations, thereby achieving the purpose of light source diffusion. In addition, a diffuser plate is usually provided above the reflective film. The diffusion plate is supported by the supporting member arranged on the bottom plate through the perforation, and the light leaving the reflective film passes through the diffusion plate to generate uniform backlight. However, the reflective film includes multiple blocks, and the arrangement of perforations in each block is repeated. In the central part of the reflective film, the positions adjacent to each block can supplement the amount of light through the adjacent blocks, so the uniformity of light distribution can still be maintained. At the same time, in the part close to the edge of the reflective film, since there are no adjacent blocks that complement each other, there will be more obvious distribution of bright and dark bands.

In view of this, how to design a novel backlight module for the liquid crystal display, or effectively improve the existing backlight module, to overcome the above-mentioned defects or deficiencies of the prior art, is an urgent need for relevant technical personnel in the industry. A problem solved.

Contents of the invention

Aiming at the above defects in the prior art backlight module for liquid crystal display, the present invention provides a backlight module for liquid crystal display.

According to one aspect of the present invention, a backlight module for a liquid crystal display is provided, including:

A back plate, including a reflective sheet and an LED light source, the LED light source is arranged above the reflective sheet;

a porous optical control film overlying the backsheet; and

A composite diffuser plate located above the porous optical control film, wherein the composite diffuser plate includes:

a first diffusion layer comprising first diffusion particles;

a transparent layer located above the first diffusion layer; and

a second diffusion layer located above the transparent layer,

Wherein, the composite diffuser plate refracts, reflects and/or scatters the light from the LED light source through the first diffuser layer and the second diffuser layer, so as to eliminate Point moiré (dotmura).

In one embodiment, the second diffusion layer includes second diffusion particles, and the concentration of the second diffusion particles is greater than or equal to the concentration of the first diffusion particles.

In one embodiment, the haze of the second diffusing particles is greater than or equal to the haze of the first diffusing particles.

In one embodiment, the upper surface of the second diffusion layer further includes a microlens structure.

In one embodiment, the second diffusion layer is a reflective layer, a microlens structure or a semi-transmissive and semi-reflective layer.

In one embodiment, the backlight module further includes a reflective brightness enhancement film (DBEF), located above the composite diffuser plate.

In one of the embodiments, the porous optical control film has a plurality of holes distributed at intervals. On the plane where the film layer is located, the hole pitch in the horizontal direction is P1, and the hole pitch in the vertical direction is P2, then P1 <=T and P2<=T, wherein T is the thickness of the composite diffuser plate.

The backlight module for liquid crystal display of the present invention includes a back plate, a porous optical control film and a composite diffuser plate. The back plate includes a reflection sheet and an LED light source, and the LED light source is arranged above the reflection sheet. A porous optical control film is located over the backplane. A composite diffuser plate sits above the porous optical control membrane. The composite diffuser plate includes a first diffuser layer, a transparent layer and a second diffuser layer. The first diffusion layer includes first diffusion particles, the transparent layer is located above the first diffusion layer, and the second diffusion layer is located above the transparent layer. Refract, reflect and/or scatter the light to eliminate the dotmura when the liquid crystal display displays images. Compared with the prior art, the present invention designs a composite diffusion plate, and the upper and lower sides of the transparent layer are respectively provided with diffusion layers with a diffusion function, and these diffusion layers can be used to atomize the light emitted by the LED light source to avoid There are obvious distribution of bright and dark bands, eliminating bad situations such as point moiré on the screen.

Description of drawings

Readers will have a clearer understanding of various aspects of the present invention after reading the detailed description of the present invention with reference to the accompanying drawings. in,

FIG. 1A shows a schematic structural view of a backlight module for a liquid crystal display in the prior art;

FIG. 1B shows a schematic structural view of another backlight module for liquid crystal displays in the prior art;

FIG. 2 shows a schematic structural view of a backlight module with a composite diffuser plate according to an embodiment of the present invention;

Figure 3A shows a first embodiment of the composite diffuser plate of Figure 2;

Figure 3B shows a second embodiment of the composite diffuser plate of Figure 2;

Fig. 4 shows a schematic diagram of the relationship between the thickness of the composite diffuser plate and the spacing of the porous optical control film in a specific embodiment of the backlight module of Fig. 2; and

FIG. 5A to FIG. 5D are respectively schematic structural diagrams of alternative embodiments of the backlight module with a composite diffuser plate in FIG. 2 .

detailed description

In order to make the technical content disclosed in this application more detailed and complete, reference may be made to the drawings and the following various specific embodiments of the present invention, and the same symbols in the drawings represent the same or similar components. However, those skilled in the art should understand that the examples provided below are not intended to limit the scope of the present invention. In addition, the drawings are only for schematic illustration and are not drawn according to their original scale.

The specific implementation manners of various aspects of the present invention will be further described in detail below with reference to the accompanying drawings.

FIG. 1A shows a schematic structural diagram of a backlight module for a liquid crystal display in the prior art. FIG. 1B shows a schematic structural diagram of another backlight module for liquid crystal displays in the prior art.

Referring to FIG. 1A , a conventional backlight module includes a backplane 10 , a porous optical control film (Golffilm) 12 , a diffuser plate (Diffuserplate) 14 and a multilayer optical film 16 . Wherein, the backplane 10 includes a reflection sheet 102 and a plurality of LED light sources 104 . The LED light sources 104 are distributed above the reflective sheet 102 . The porous optical control film 12 is located above the backplane 10 and has a vertical height H1 from the backplane 10 . The diffusion plate 14 is located above the porous optical control film 12 and is at a vertical height H2 from the porous optical control film 12 . In addition, the thickness d1 of the diffusion plate 14 is generally between 1.5 mm and 2 mm. A multilayer optical film 16 is positioned over the diffuser plate 14 . In order to make the light beams transmitted by the multilayer optical film 16 more uniform, there are often certain specifications for the value of the height H2, for example, H2 must be greater than 3mm-10mm, which will make the cavity thicker.

In order to greatly reduce the thickness of the cavity, referring to FIG. 1B , the conventional backlight module attaches the porous optical control film 12 to the lower surface of the diffusion plate 14 . The vertical height of the porous optical control film 12 from the backplane 10 is H3. Comparing FIG. 1A with FIG. 1B , it is easy to see that the distance H2 between the diffuser plate 14 and the porous optical control film 12 in FIG. 1A is eliminated by bonding each other. Moreover, the thickness d2 of the diffuser plate 14 is generally between 2mm˜4mm. However, as previously described, the perforation arrangement of the porous optical control film 12 is repeated. In the part close to the central position, the light distribution can be maintained uniformly by supplementing the adjacent blocks together; in the part close to the edge, there will be more obvious distribution of bright and dark bands because there is no mutual supplement of light. That is, a problem of dotmura occurs.

In order to solve the above problems in the prior art, the present invention designs a backlight module for a liquid crystal display, the backlight module especially includes a composite diffuser plate. FIG. 2 shows a schematic structural diagram of a backlight module with a composite diffuser plate according to an embodiment of the present invention.

Referring to FIG. 2 , in this embodiment, the backlight module of the present invention at least includes a backplane 20 , a porous optical control film (Golffilm) 22 and a composite diffuser DP. Wherein, the backplane 20 includes a reflection sheet 202 and an LED light source 204 . The porous optical control film 22 is located on the back plate 20 . The composite diffuser plate DP is located above the porous optical control film 22 .

Moreover, the composite diffuser plate DP includes a first diffuser layer 241 , a transparent layer 24 and a second diffuser layer 243 . The first diffusion layer 241 includes first diffusion particles. The transparent layer 24 is located above the first diffusion layer 241 . The second diffusion layer 243 is located above the transparent layer 24 . Wherein, the composite diffuser plate DP refracts, reflects and/or scatters the light from the LED light source 204 through the first diffuser layer 241 and the second diffuser layer 243, so as to eliminate dotmura when the liquid crystal display displays images. . It can be seen from the above that, compared with the prior art, the present invention designs a composite diffuser plate, and the upper and lower sides of the transparent layer are respectively provided with diffusion layers with a diffusion function, and these diffusion layers are used to diffuse the light emitted by the LED light source. Fogging, so as to avoid the obvious distribution of bright and dark bands, so as to eliminate bad situations such as point moiré on the screen.

FIG. 3A shows a first embodiment of the composite diffuser plate of FIG. 2 . Referring to FIG. 3A, in this embodiment, the composite diffuser plate includes a first diffuser layer 241a, a transparent layer 24 and a second diffuser layer 243a. The first diffusion layer 241a includes first diffusion particles. The second diffusion layer 243a includes second diffusion particles, wherein the concentration of the second diffusion particles of the second diffusion layer 243a is smaller than the concentration of the first diffusion particles of the first diffusion layer 241a. Correspondingly, the haze of the second diffusing particles is smaller than that of the first diffusing particles. In addition, the backlight module further includes a reflective brightness enhancement film (dual brightness enhancement film, DBEF) 26 located above the second diffusion layer 243a of the composite diffusion plate DP.

FIG. 3B shows a second embodiment of the composite diffuser plate of FIG. 2 . Referring to FIG. 3B , in this embodiment, the composite diffuser plate includes a first diffuser layer 241b, a transparent layer 24 and a second diffuser layer 243b. The first diffusion layer 241b includes first diffusion particles. The second diffusion layer 243b includes second diffusion particles, wherein the concentration of the second diffusion particles in the second diffusion layer 243b is greater than or equal to the concentration of the first diffusion particles in the first diffusion layer 241b. Correspondingly, the haze of the second diffusing particles is greater than or equal to the haze of the first diffusing particles. Comparing Fig. 3B with Fig. 3A, the main difference is that the concentration and haze of the diffusing particles in the first diffusing layer and diffusing particles in the second diffusing layer have changed. Experimental tests have proved that when the concentration and haze of the second diffusion particles are greater than or equal to the concentration and haze of the first diffusion particles, the point moiré removal effect is better.

FIG. 4 is a schematic diagram showing the size relationship between the thickness of the composite diffuser plate and the spacing of the porous optical control film in a specific embodiment of the backlight module in FIG. 2 .

Referring to Fig. 4, the porous optical control film 22 has a plurality of holes distributed at intervals, on the plane where the film layer is located (that is, the X-Y plane), the center point of the adjacent holes is the hole spacing in the horizontal direction (that is, the X direction) is P1, and the hole pitch in the vertical direction (ie, Y direction) is P2. The height (or thickness) of the composite diffuser plate in the Z direction is T. In consideration of uniform light mixing, P1<=T and P2<=T can be made. For example, the horizontal pitch P1 is 3.2 mm, the vertical pitch P2 is 3 mm, and the thickness T of the composite diffuser plate is 4 mm.

FIG. 5A to FIG. 5D are respectively schematic structural diagrams of alternative embodiments of the backlight module with a composite diffuser plate in FIG. 2 .

Referring to FIG. 5A , the upper surface of the second diffusion layer of the composite diffuser DP1 further includes a microlens structure 30 , and the light emitted from the diffuser can be further diffused by the microlens structure 30 . In addition, the second diffusion layer of the composite diffuser plate can also be configured as a reflective layer, a micro-lens structure or a semi-transmissive semi-reflective layer (transflective layer). For example, in FIG. 5B , the second diffusion layer 32 of the composite diffuser plate DP2 is a reflective layer. As another example, in FIG. 5C , the second diffusion layer 34 of the composite diffuser plate DP3 is a microlens structure. For another example, in FIG. 5D , the second diffusion layer 36 of the composite diffuser plate DP4 is a semi-transparent semi-reflective layer.

The backlight module for liquid crystal display of the present invention includes a back plate, a porous optical control film and a composite diffuser plate. The back plate includes a reflection sheet and an LED light source, and the LED light source is arranged above the reflection sheet. A porous optical control film is located over the backplane. A composite diffuser plate sits above the porous optical control membrane. The composite diffuser plate includes a first diffuser layer, a transparent layer and a second diffuser layer. The first diffusion layer includes first diffusion particles, the transparent layer is located above the first diffusion layer, and the second diffusion layer is located above the transparent layer. Refract, reflect and/or scatter the light to eliminate the dotmura when displaying images on the liquid crystal display. Compared with the prior art, the present invention designs a composite diffusion plate, and the upper and lower sides of the transparent layer are respectively provided with diffusion layers with a diffusion function, and these diffusion layers can be used to atomize the light emitted by the LED light source to avoid There are obvious distribution of bright and dark bands, eliminating bad situations such as point moiré on the screen.

Hereinbefore, specific embodiments of the present invention have been described with reference to the accompanying drawings. However, those skilled in the art can understand that without departing from the spirit and scope of the present invention, various changes and substitutions can be made to the specific embodiments of the present invention. These changes and substitutions all fall within the scope defined by the claims of the present invention.

Claims (7)

1. A backlight module for liquid crystal display, characterized in that, said backlight module comprises: A back plate, including a reflective sheet and an LED light source, the LED light source is arranged above the reflective sheet; a porous optical control film overlying the backsheet; and A composite diffuser plate located above the porous optical control film, wherein the composite diffuser plate includes: a first diffusion layer comprising first diffusion particles; a transparent layer located above the first diffusion layer; and a second diffusion layer located above the transparent layer, Wherein, the composite diffuser plate refracts, reflects and/or scatters the light from the LED light source through the first diffuser layer and the second diffuser layer, so as to eliminate Point moiré. 2. The backlight module according to claim 1, wherein the second diffusion layer includes second diffusion particles, and the concentration of the second diffusion particles is greater than or equal to the concentration of the first diffusion particles. 3. The backlight module according to claim 2, wherein the haze of the second diffusing particles is greater than or equal to the haze of the first diffusing particles. 4. The backlight module according to claim 2, wherein the upper surface of the second diffusion layer further comprises a microlens structure. 5 . The backlight module according to claim 1 , wherein the second diffusion layer is a reflective layer, a microlens structure, or a semi-transparent semi-reflective layer. 6 . The backlight module according to claim 1 , further comprising a reflective brightness enhancement film, which is located above the composite diffuser. 7. The backlight module according to claim 1, wherein the porous optical control film has a plurality of holes distributed at intervals, on the plane where the film layer is located, the hole spacing in the horizontal direction is P1, and the vertical hole spacing is P1. The hole spacing in the direction is P2, then P1<=T and P2<=T, where T is the thickness of the composite diffuser plate.