CN101285902B - Diffusion plate group - Google Patents

Abstract

The invention provides a diffusion plate group, which comprises: an upper diffuser plate and a lower diffuser plate. The light-emitting surface of the upper diffusion plate is provided with a plurality of first microstructures, the thickness of the upper diffusion plate is more than 0.5mm, and the penetration rate is more than 90%, the lower diffusion plate is arranged below the upper diffusion plate, and the thickness of the lower diffusion plate is more than 0.5mm, and the penetration rate is 50% -70%. In addition, the invention also provides a direct type backlight module which uses the diffusion plate group.

Description

Diffusion plate group

technical field

The invention relates to an optical diffusion plate, in particular to a diffusion plate with a plurality of microstructures.

Background technique

In recent years, traditional cathode ray tube displays (commonly known as CRT displays) have been gradually replaced by liquid crystal displays. The main reason is that the amount of radiation emitted by liquid crystal displays is much smaller than that of CRT displays. Manufacturing costs are also significantly reduced. Generally speaking, a liquid crystal display includes a backlight module and a liquid crystal panel. The main function of the backlight module is to provide a light source for the liquid crystal display.

Please refer to FIG. 1 , which shows a conventional backlight module. The backlight module 100 is mainly composed of a cold cathode fluorescent lamp (CCFL) 110, a reflector 120, a diffuser plate 130, and a plurality of optical films 140. The CCFL 110 is used to generate a light source, and the reflector 120 is used to The light generated by the cold cathode fluorescent lamps 110 arranged at intervals is directed toward the direction of the diffuser plate 130 . In addition, the optical film 140 includes: a diffusion film 142 and a Brightness Enhancement Film (commonly known as: BEF) 144 . The function of the diffuser plate 130 is mainly to diffuse the light emitted by the cold cathode fluorescent lamp 110, so that the light irradiated to the liquid crystal panel (not shown) can be more uniform, and less likely to be generated on the display surface of the liquid crystal display. The phenomenon of uneven brightness. In addition, since the diffusion plate 130 has a plurality of light diffusion particles, the transmittance of the diffusion plate 130 will decrease. Generally, the transmittance of the diffusion plate 130 is 50%-70%.

However, the diffuser plate 130 is usually not enough to completely overcome the phenomenon of uneven brightness, so a diffuser film 142 is needed to diffuse the light more uniformly. In addition, since the light emitted by the diffusion film 142 has a relatively large angle of light, it is necessary to add a brightness enhancement film 144 above the diffusion film 142 . The thickness of the brightness enhancement film 144 is about 0.062mm˜0.375mm. Since the brightness enhancement film 144 is provided with a plurality of prism structures 144a, it has the effect of concentrating light, which can make the light angle of the light emitted by the brightness enhancement film 144 smaller, thereby increasing the brightness of the backlight module 100 within the viewing angle range. brightness.

However, due to the relationship between the manufacturing process and the material, the cost of the brightness enhancement film 144 is often the highest in the backlight module 100. In order to reduce the overall cost of the backlight module 100, how can the backlight module be maintained without the brightness enhancement film 144? The overall brightness of 100 is worthy of consideration by those skilled in the art.

Contents of the invention

The purpose of the present invention is to provide a diffuser plate set, so that the backlight module using the diffuser plate set does not need to use a brightness enhancement film, thereby reducing the overall cost of the backlight module.

Another object of the present invention is to provide a direct type backlight module, the direct type backlight module has a diffusion plate set. Due to the diffusion plate group, the direct-type backlight module does not need to be provided with a brightness enhancement film, thereby reducing the overall cost of the direct-type backlight module.

According to the above and other objectives, the present invention provides a diffuser plate set, which includes: an upper diffuser plate and a lower diffuser plate. Wherein, the light-emitting surface of the upper diffusion plate has a plurality of first microstructures, and these first microstructures are prism structures, which have the effect of concentrating light. The height of the first microstructures is 140 μm, and the first microstructures are The distance between a microstructure is 300 μm, the thickness of the upper diffusion plate is 0.5 mm to 2 mm and the penetration rate is over 90%, and the lower diffusion plate is arranged under the upper diffusion plate, and the thickness of the lower diffusion plate is 0.5 mm. mm to 2 mm and having a plurality of light diffusing particles, so that the transmittance of the lower diffusing plate is 50% to 70%; there is a gap between the lower diffusing plate and the upper diffusing plate;

Wherein, when light passes through the upper diffuser plate and the lower diffuser plate, because the upper diffuser plate and the lower diffuser plate are media with different refractive indices, they can be used to cause refraction, reflection and scattering of light, In order to achieve the effect of light diffusion.

In the above diffuser plate set, the penetration rate of the upper diffuser plate is preferably above 99%. Moreover, the penetration rate of the lower diffusion plate is preferably 55%.

In the above diffuser plate set, the thickness of the upper diffuser plate is preferably 0.8mm. In addition, the thickness of the lower diffusion plate is preferably 1.5mm.

In the above diffuser plate group, the upper diffuser plate and the lower diffuser plate are mainly composed of transparent materials, and the upper diffuser plate is doped with a plurality of light diffusion particles; wherein the transparent material is selected from Group consisting of polymethyl methacrylate, polycarbonate, polystyrene, copolymer of methyl methacrylate and styrene monomer, polypropylene, polyethylene and polyethylene terephthalate.

In the above diffuser plate group, the light incident surface of the upper diffuser plate has a plurality of second microstructures, and the arrangement direction of the second microstructures is perpendicular to the arrangement direction of the first microstructures.

In the above diffuser plate set, the light emitting surface of the lower diffuser plate has a plurality of third microstructures. Moreover, the light incident surface of the lower diffusion plate has a plurality of fourth microstructures, and the arrangement direction of the fourth microstructures is perpendicular to the arrangement direction of the third microstructures.

According to the above and other objectives, the present invention provides a direct-type backlight module, the direct-type backlight module includes: a plurality of light sources, a reflector and a diffuser plate set. Wherein, there is a distance between the light sources, and the light sources are placed in the reflector. Moreover, the diffuser plate set is arranged above the light sources, and the diffuser plate set includes an upper diffuser plate and a lower diffuser plate. Wherein, the light emitting surface of the upper diffusion plate has a plurality of first microstructures, and these first microstructures have the effect of concentrating light, the thickness of the upper diffusion plate is more than 0.5mm and the transmittance is more than 90%, and the lower The plate is arranged under the upper diffuser plate, wherein the thickness of the lower diffuser plate is more than 0.5mm and the penetration rate is 50%-70%.

Since the upper diffusion plate in the diffusion plate set of the present invention has high penetration rate and has a microstructure, the upper diffusion plate can replace the existing brightness enhancement film, thereby reducing the cost of the backlight module.

In order to make the above objects, features and advantages of the present invention more comprehensible, the following will be described in detail with examples and accompanying figures. In addition, it should be noted that the accompanying illustrations are only schematic and not drawn according to a certain scale.

Description of drawings

Figure 1 shows an existing backlight module;

Figure 2 shows a backlight module of the first embodiment;

Fig. 3 shows the diffusion plate group of Fig. 2;

Figure 4 shows a partial perspective view of the upper diffusion plate;

FIG. 5A and FIG. 5B illustrate a diffuser plate group of the second embodiment, FIG. 5A is a front view, and FIG. 5B is a side view;

FIG. 6A and FIG. 6B illustrate a diffuser plate set of the third embodiment, FIG. 6A is a front view, and FIG. 6B is a side view.

Explanation of reference numerals: 100: backlight module; 110: cold cathode fluorescent lamp; 120: reflector; 130: diffusion plate; 140: optical film; 142: diffusion film; 144: brightness enhancement film; 144a: prism structure; 200 : backlight module; 210: light source; 220: reflector; 230, 230', 230": diffuser plate group; 232, 232': upper diffuser plate; 232a, 232a', 234a': light-emitting surface; 232b, 232b': 232c, 232c', 234c': light incident surface; 232d': second microstructure; 234: lower diffusion plate; 234b': third microstructure; 234d': fourth microstructure .

Detailed ways

Please refer to FIG. 2 , which shows a backlight module of the first embodiment. The backlight module 200 includes a light source 210 , a reflector 220 , and a diffusion plate set 230 . The light source 210 is, for example, an array of CCFLs or Light Emitting Diodes (commonly known as LEDs) for providing illumination light. In addition, the reflection cover 220 is used to guide the light generated by the light source 210 to a direction towards the diffusion plate set 230 .

Next, please refer to FIG. 3 at the same time. FIG. 3 shows the diffuser plate set in FIG. 2 . The diffuser plate set 230 includes an upper diffuser plate 232 and a lower diffuser plate 234, the light emitting surface 232a of the upper diffuser plate 232 has a plurality of first microstructures 232b, and the lower diffuser plate 234 is disposed below the upper diffuser plate 232, The number of light-diffusing particles in the lower diffuser plate 234 is more than that of the upper diffuser plate 232 , so its transmittance is lower than that of the upper diffuser plate 232 . The penetration rate of the lower diffusion plate 234 is 50%-70%, preferably 55%; the penetration rate of the upper diffusion plate 232 is above 90%, preferably above 99%.

The upper diffuser plate 232 and the lower diffuser plate 234 are mainly composed of transparent materials, and are doped with a plurality of light-diffusing particles. When the plate 234 is in place, it will continuously pass through two media with different refractive indices, resulting in refraction, reflection and scattering of light, so as to achieve the effect of light diffusion. The transparent material is, for example, polymethyl methacrylate (PMMA for short), polycarbonate (PC for short), polystyrene (PS for short), methyl methacrylate and styrene alone. Copolymer ((MethylMethacrylate) Styrene, referred to as MS), polypropylene (Polypropene, referred to as PP), polyethylene (Polyethylene, referred to as PE), polyethylene terephthalate (polyethylene terephthalate, referred to as PET), preferably It is a copolymer of methyl methacrylate and styrene monomer. In addition, the transmittance of the upper diffuser plate 232 and the lower diffuser plate 234 can be adjusted by the concentration of doped light-diffusing particles. The higher the concentration of light-diffuser particles, the lower the transmittance of the diffuser plate. Therefore, the concentration of the light diffusion particles in the upper diffusion plate 232 is lower than that in the lower diffusion plate 234 , and no light diffusion particles may be added in the upper diffusion plate 232 . In this embodiment, for example, an optical measuring instrument (model: NDH 2000) produced by Japan's business-Measurement Technology Research Institute (KEISOKU GIKEN) is used to measure the transmittance of the upper diffuser plate 232 and the lower diffuser plate 234 . In addition, the upper diffuser plate 232 and the lower diffuser plate 234 are formed by extruding, for example.

The thickness of the upper diffuser plate 232 and the lower diffuser plate 234 are both above 0.5 mm, for example, 0.5 mm˜2 mm. The thickness of the upper diffuser plate 232 is preferably 0.8 mm, and the thickness of the lower diffuser plate 234 is preferably 1.5 mm.

Next, please refer to FIG. 3 and FIG. 4 at the same time. FIG. 4 is a partial perspective view of the upper diffusion plate. Since the first microstructure 232b is a prism structure, it has the function of concentrating light. The height of the first microstructures 232b is about 140 μm, and the distance between the first microstructures 232b is about 300 μm. Of course, those skilled in the art can also design the first microstructure 232b into other shapes that can exert light-gathering effects, such as conical or hemispherical.

Due to the brightness enhancement effect that the upper diffuser plate 232 can also achieve, the brightness enhancement film 144 can be reduced in the backlight module 200 . Currently on the market, the total cost of two diffusion films 142 plus one brightness enhancement film 144 and the diffusion plate 130 is about NT$750, and the cost of the diffusion plate set 230 is about NT$350. Since the prices of optical film and diffusion plate are constantly changing, the above is only an explanation of the current price. In any case, the price of the diffusion plate set 230 in this case is indeed about 50% lower than the existing price, so it can achieve the purpose of reducing the overall cost of the backlight module .

Moreover, in addition to the light diffusion effect of the lower diffuser plate 234, when the upper diffuser plate 232 and the lower diffuser plate 234 are bonded together, the gap (not shown) generated therebetween will refract the light passing therebetween, further increasing The light diffusion effect of the diffuser plate set 230 . Moreover, compared with the existing brightness-enhancing film 144, the upper diffuser plate 232 has a larger thickness, and the path formed by light in it is longer than the path formed by light in the brightness-enhancing film 144, which will also Further increase the diffusion effect of light. Therefore, the diffusion film 142 may not be provided in the backlight module 200 , so that the overall cost is further reduced.

In the first embodiment, only the light-emitting surface 232a of the upper diffuser plate 232 has microstructures (namely: the first microstructures 232b), but those skilled in the art can also make the light-incidence surface 232c or The microstructures are arranged on the lower diffuser plate 234, which will be described below with examples.

Please refer to FIG. 5A and FIG. 5B . FIG. 5A and FIG. 5B illustrate a diffuser plate set of the second embodiment, FIG. 5A is a front view, and FIG. 5B is a side view. The diffuser plate group 230' is composed of an upper diffuser plate 232' and a lower diffuser plate 234, wherein the upper diffuser plate 232' is not only provided with a first microstructure 232b' on the light output surface 232a', but also has a light incident surface 232c' A second microstructure 232d' is disposed thereon. It can be seen from FIG. 5A and FIG. 5B that the arrangement direction of the second microstructures 232d' is perpendicular to the arrangement direction of the first microstructures 232b'.

Next, please refer to FIG. 6A and FIG. 6B . FIG. 6A and FIG. 6B illustrate a diffuser plate set in the third embodiment, FIG. 6A is a front view, and FIG. 6B is a side view. The diffuser plate group 230" is composed of an upper diffuser plate 232 and a lower diffuser plate 234', wherein the light emitting surface 234a' of the lower diffuser plate 234' is provided with a third microstructure 234b', and the light incident surface of the lower diffuser plate 234' 234c' is provided with a fourth microstructure 234d'. And, as can be seen from Figure 6A and Figure 6B, the arrangement direction of the third microstructure 234b' is perpendicular to the arrangement direction of the fourth microstructure 234d'. Certainly, this Those skilled in the art may also not set the fourth microstructure 234d' due to cost considerations. In the diffusion plate group 230' and the diffusion plate group 230", due to the second microstructure 232d', the third microstructure 234b ' and the fourth microstructure 234d', so the times of refraction and reflection of light in the diffuser plate set 230', 230" can be increased, so that the diffuser plate set 230', 230" has a better light diffusion effect.

The present invention is described above with examples, but they are not intended to limit the scope of the claims of the present invention. The scope of the claims should be determined by the claims described in the claims and their equivalent fields. All changes or modifications made by those skilled in the art without departing from the spirit or scope of this patent belong to the equivalent changes or designs completed under the spirit disclosed by the present invention, and should be included in the claims. within the scope of the claims.

Claims (8)

1. A diffusion plate group, characterized in that, comprising: An upper diffusion plate, the light-emitting surface has a plurality of first microstructures, the first microstructures are prism structures, which have the effect of concentrating light, the height of the first microstructures is 140 μm, and the The distance between the first microstructures is 300 μm, the thickness of the upper diffusion plate is 0.5mm-2mm, and the transmittance is above 90%; and The lower diffusion plate is arranged under the upper diffusion plate, the thickness of the lower diffusion plate is 0.5mm-2mm, and there are a plurality of light-diffusing particles, so that the transmittance of the lower diffusion plate is 50%-70% %, there is a gap between the lower diffusion plate and the upper diffusion plate; Wherein, when light passes through the upper diffuser plate and the lower diffuser plate, because the upper diffuser plate and the lower diffuser plate are media with different refractive indices, they can be used to cause refraction, reflection and scattering of light, In order to achieve the effect of light diffusion. 2. The diffuser plate set according to claim 1, wherein the upper diffuser plate and the lower diffuser plate are mainly made of transparent material, and the upper diffuser plate is doped with a plurality of light-diffusing particles ; wherein the transparent material is selected from polymethyl methacrylate, polycarbonate, polystyrene, a copolymer of methyl methacrylate and styrene monomer, polypropylene, polyethylene and polyethylene terephthalate A group of diesters. 3. The diffuser plate set according to claim 1, wherein the penetration rate of the lower diffuser plate is 55%. 4. The diffuser plate set according to claim 1, wherein the penetration rate of the upper diffuser plate is above 99%. 5. The diffuser plate set according to claim 1, wherein the thickness of the upper diffuser plate is 0.8 mm, and the thickness of the lower diffuser plate is 1.5 mm. 6. The diffusion plate group according to claim 1, characterized in that: the light incident surface of the upper diffusion plate has a plurality of second microstructures, and the arrangement direction of the second microstructures is the same as that of the first microstructures. The arrangement direction of the microstructures is vertical. 7. The diffuser plate assembly according to claim 1, characterized in that: the light emitting surface of the lower diffuser plate has a plurality of third microstructures. 8. The diffusion plate group according to claim 1, characterized in that: the light incident surface of the lower diffusion plate has a plurality of fourth microstructures, and the arrangement direction of the fourth microstructures is the same as that of the third microstructures. The arrangement direction of the microstructures is vertical.

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