CN101546062A - Diffusion plate for backlight source of liquid crystal display - Google Patents

Abstract

The invention relates to a diffuser plate for a backlight source of a liquid crystal display, which at least consists of a substrate layer and a side layer to form a layered composite structure. The side layer is two layers, and the substrate layer is sandwiched therein. The substrate layer is made of polystyrene A blending layer composed of a substrate and a light diffusing agent, and a blending layer composed of a polyester-containing transparent substrate, a light diffusing agent and a benzotriazole ultraviolet absorber is used for the side layer. Due to the use of PS as the base material, the diffuser plate has a high light transmittance; and the water absorption rate of PS is small, and the influence of deformation caused by changes in environmental humidity is small, so that the diffuser plate has good dimensional stability; in addition, The side layer adopts a blended layer, which can reduce the yellowing caused by ultraviolet radiation and prolong the service life of the diffusion plate.

Description

Diffusion plate for LCD backlight

technical field

The invention relates to a light diffusion plate, in particular to a light diffusion plate applied to a liquid crystal display backlight source, and belongs to the technical field of polymer materials.

Background technique

The Liquid Crystal Display (LCD) device itself is a non-luminous display device. If it is not a reflective application, it needs to be equipped with a backlight to realize the display function.

The backlight module can be divided into two types: edge-lit and direct-lit. The side-light type installs a light source on one or more sides of the LCD screen, guides and scatters the light through the light guide plate to become a surface light source that can illuminate the LCD screen, and makes the illumination more uniform through the diffusion plate. The side-light design is more suitable for small and medium-sized liquid crystal displays, but for large-size liquid crystal displays (and LCD TVs), the light utilization rate of the side-light design is low and the number of light sources that can be accommodated is limited, which cannot meet the needs of large-size liquid crystal displays. brightness requirements.

The direct-down design does not use a light guide plate, but directly sets multiple light sources on the back of the LCD screen. Light sources mainly include cold cathode tubes (CCFL), light emitting diodes (LED) and electroluminescent devices (ELD). No matter what kind of light source, what the current mature technology can provide is point light source or line light source, which needs multiple common use to illuminate the LCD screen. In order to eliminate the traces of the light source that alternates between light and dark, it is necessary to make the light emitted by the light source pass through the diffuser plate to form a uniform surface light source. When making a diffuser plate, not only the uniformity is required, but the permeability (transmittance) of the diffuser plate is also crucial to the brightness of the liquid crystal display. In addition, the ultraviolet rays in the light source cause the yellowing of the diffuser plate and the decrease in life, and the heat of the light source causes the thermal deformation of the diffuser plate, etc., all need to be considered.

Existing technology, such as the diffusion plate disclosed by Chinese Patent Publication No. CN1402083A title "diffusion plate and its manufacturing method", is composed of transparent substrate (such as acrylic plate, polycarbonate PC plate or glass, etc.) and liquid diffusion The membrane is coated and combined by polymerization to form a diffuser plate with a double-layer composite structure. Obviously, this existing diffusion plate, because the substrate does not have or seldom has the light diffusion effect, but only relies on the primary light diffusion of the diffusion film, and because it adopts the coating production method, the surface of the diffusion film The flatness and parallelism between the diffusion film and the substrate are poor, so the optical effects such as haze and brilliance of this existing diffusion plate are relatively poor, and the quality of light diffusion is not ideal, and the diffusion caused by ultraviolet rays There is also no effective countermeasure against the yellowing phenomenon of the board and the decrease in life.

Contents of the invention

The object of the present invention is to provide a diffuser plate for a backlight source of a liquid crystal display in order to solve the above-mentioned problems in the prior art.

The object of the present invention is achieved through the following technical solutions: a diffuser plate for backlight of liquid crystal display, which at least consists of a substrate layer and a side layer to form a layered composite structure, the side layer is two layers, and the substrate layer is sandwiched therein. The substrate layer is a blended layer composed of polystyrene as the base material and a light diffusing agent, and the side layer is a blended layer composed of a transparent substrate containing polyester, a light diffusing agent and a benzotriazole ultraviolet absorber.

Further, in the aforementioned diffusion plate for backlight of liquid crystal display, wherein: the thickness range of the light diffusion plate is 0.5 mm to 3 mm, and the single layer thickness of the side layer is 0.04 mm to 0.06 mm.

Still further, the above-mentioned diffuser plate for backlight of liquid crystal display, wherein: the side layer is a blend layer composed of polymethyl methacrylate as a base material, a light diffusing agent and a benzotriazole ultraviolet absorber.

Furthermore, the above-mentioned diffusion plate for liquid crystal display backlight, wherein: in the substrate layer, the weight content of the light diffusing agent is 0.5% to 5%, and the rest is the substrate; in the side layer, the light diffusing agent The weight content is 0.5%-5%, the weight content of the ultraviolet absorber is 0.1%-0.3%, and the rest is the base material.

Further, the above-mentioned diffusion plate for LCD backlight is a layered composite structure composed of at least a substrate layer and a side layer, the side layer is two layers, and the substrate layer is sandwiched therein. The substrate layer is made of Polystyrene (PS) is the base material and a blended layer composed of light diffusing agent, and the side layer is made of polymethyl methacrylate and styrene copolymer (MS) as the base material, light diffusing agent and benzotriazole A blend layer composed of UV absorbers.

Furthermore, in the above-mentioned diffusion plate for liquid crystal display backlight, the side layer is a blend layer composed of polycarbonate as the base material, a light diffusing agent and a benzotriazole ultraviolet absorber.

Furthermore, in the above-mentioned diffusion plate for liquid crystal display backlight, wherein, among the substrate layer, the weight content of the light diffusing agent is 0.5% to 4%, and the rest is the substrate; among the side layers, the weight content of the light diffusing agent is The weight content is 0.5%-4%, the weight content of the ultraviolet absorber is 0.1%-0.2%, and the rest is the base material.

Further, the above-mentioned diffusion plate for backlight of liquid crystal display, wherein, the side layer is composed of polymethyl methacrylate and styrene copolymer as a base material, a light diffusing agent and a benzotriazole ultraviolet absorber blended layer.

Still further, in the above-mentioned diffusion plate for liquid crystal display backlight, wherein, in the substrate layer, the weight content of the light diffusing agent is 0.5% to 4%, and the rest is the base material; among the side layers, the light diffusing agent The weight content is 0.5%-4%, the weight content of the ultraviolet absorber is 0.1%-0.2%, and the rest is the base material.

Thus, the present invention provides a diffusion plate for a backlight source of a liquid crystal display. On the premise of effectively ensuring good light permeability (transmittance) and uniformity, the diffusion plate has a strong ability to resist ultraviolet rays, Good dimensional stability and long service life. It adopts a multi-layer composite structure, that is, it is composed of two outer layers and a substrate layer sandwiched between the two outer layers. The substrate layer, the base material of the outer layer and the light diffusing agent are all transparent materials. Different rates of light refract, scatter, and reflect light passing through it, making the distribution of light uniform. Because both the substrate layer and the outer layer are blended layers containing a light diffusing agent, the structure of the present invention can obtain better light distribution uniformity than the structure of coating a diffusing film on a transparent substrate. By using polystyrene (PS) as the base material, the diffusion plate can have a higher light transmittance. At the same time, polystyrene has a small water absorption rate and is less affected by deformation caused by changes in environmental humidity, which can make the diffusion plate have better dimensional stability. The two outer layers contain ultraviolet absorbers, which make the diffusion plate have better anti-ultraviolet ability, reduce the yellowing of the plate caused by ultraviolet radiation, and greatly reduce the production cost of the long service life. The invention has good implementation effect and expands the space for technical progress in the field.

Description of drawings

Objects, advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments. These embodiments are only typical examples of applying the technical solutions of the present invention, and all technical solutions formed by adopting equivalent replacements or equivalent transformations fall within the protection scope of the present invention.

Fig. 1 is a schematic structural view of a light diffusion plate of the present invention.

The meanings of the symbols in the figure are: 1—substrate layer, 2a/2b—side layer.

Detailed ways

[Example 1]

As shown in FIG. 1 , a diffusion plate for a liquid crystal display backlight is composed of at least a substrate layer 1 and two upper and lower side layers 2a, 2b to form a layered composite structure, and the substrate layer 1 is sandwiched between the side layers 2a and 2b. The substrate layer 1 described above is a blend layer that uses polystyrene (PS) as the base material and a light diffusing agent. agent and benzotriazole UV absorber. Moreover, the thickness range of the light diffusion plate is 0.5mm-3mm, and the thicknesses of the side layers 2a and 2b are both 0.04mm-0.06mm.

In the above-mentioned first embodiment, by using polystyrene (PS) with good light permeability as the base material of the substrate layer 1, the diffusion plate can have a higher light transmittance. At the same time, polystyrene has a small water absorption rate and is less affected by deformation caused by changes in environmental humidity, which can make the diffusion plate have better dimensional stability. Furthermore, the base materials of the two side layers 2a, 2b are all polymethyl methacrylate (PMMA), and the heat resistance of polymethyl methacrylate (PMMA) is better than polystyrene (PS), and is affected by the environment. The influence of temperature is small, which is conducive to maintaining the stability of the size of the diffuser plate. Moreover, polymethyl methacrylate (PMMA) has better anti-ultraviolet ability, and added benzotriazole ultraviolet absorber in the two side layers 2a, 2b in addition, reduced the yellowing caused by the ultraviolet radiation of the plate. can prolong the life of the diffuser plate. By adding a light diffusing agent in both the substrate layer 1 and the side layers 2a, 2b, the light emitted through the diffusing plate has better distribution uniformity.

〖Embodiment 2〗

As shown in Figure 1, a diffuser plate for a backlight source of a liquid crystal display is at least a layered composite structure composed of a substrate layer 1 and side layers 2a and 2b, the side layers 2a and 2b are two layers, and the substrate layer 1 is sandwiched therein , the substrate layer 1 is a blend layer made of polystyrene (PS) as the base material and light diffusing agent, and the side layers 2a and 2b are all made of polycarbonate (PC) as the base material and light diffusing agent And a blend layer composed of benzotriazole ultraviolet absorbers. In order to achieve the optimal use effect, the thickness range of the light diffusion plate is 0.5mm-3mm, and the thickness of the side layers 2a and 2b are both 0.04mm-0.06mm.

In the above-mentioned second specific embodiment, polystyrene (PS) is used as the base material of the substrate layer 1 , and its low water absorption rate reduces the possibility of deformation of the plate due to the influence of ambient humidity. The base material of the two side layers 2a and 2b is polycarbonate (PC), which has a high heat distortion temperature and is less affected by the ambient temperature, which is beneficial to keep the size of the diffuser plate stable. At the same time, the benzotriazole ultraviolet absorber added to the two side layers 2a and 2b reduces the effect of yellowing of the plate caused by ultraviolet radiation, and can prolong the life of the diffuser plate. Furthermore, by adding a light diffusing agent to both the substrate layer 1 and the side layers 2a and 2b, the light emitted through the diffusing plate has a better distribution uniformity.

〖Embodiment 3〗

As shown in Figure 1, a diffuser plate for a backlight source of a liquid crystal display is at least a layered composite structure composed of a substrate layer 1 and side layers 2a and 2b, the side layers 2a and 2b are two layers, and the substrate layer 1 is sandwiched therein , the substrate layer 1 is a blend layer using polystyrene (PS) as the base material and composed of a light diffusing agent, and the side layers 2a and 2b are all made of polymethyl methacrylate and styrene copolymer (MS) It is a blended layer composed of base material, light diffusing agent and benzotriazole ultraviolet absorber. In order to achieve the best combination of layered composite structures, the thickness range of the light diffusion plate is 0.5mm-3mm, and the thickness of the side layers 2a and 2b are both 0.04mm-0.06mm.

In the above-mentioned third specific embodiment, the base material of the substrate layer 1 is polystyrene (PS), which has a relatively low water absorption rate so that the diffusion plate has a good ability to prevent water absorption and deformation. The substrates of the two side layers 2a and 2b are polymethyl methacrylate (PMMA) and styrene copolymer (MS), which has high thermal stability and low water absorption, which is conducive to the stability of the size of the diffusion plate sex. At the same time, the specific gravity of polystyrene (PS) is smaller than that of polymethyl methacrylate (PMMA) and polycarbonate (PC), so that the cost of raw materials can be greatly reduced.

During specific implementation, a plastic extruder can be used to follow the steps below—

1. Prepare materials. According to the materials used in substrate layer 1, side layer 2a, 2b, weigh, stir and dehumidify respectively according to their weight percentage composition, the weight percentage composition of each component in the blend material used in substrate layer 1 is, light diffusing agent is 0.5% to 5%, and the balance is the base material; the weight percentage composition of each component in the blend material used in the side layers 2a and 2b is: light diffusing agent is 0.5% to 5%, and ultraviolet absorber is 0.1% to 0.3% %, and the balance is the base material.

2. Heating and plasticizing. The blended material used for the substrate layer 1 is extruded into a molding machine and heated and plasticized into a viscous fluid state, and then the blended material used in the side layers 2a and 2b is extruded into a molding machine and heated and plasticized into a viscous fluid state.

3. Co-extrusion. The blended material used for the substrate layer 1 and the blended materials used for the side layers 2a and 2b, which have been heated and plasticized into a viscous fluid state, are introduced simultaneously, and are combined with the composite layer distributor configured by the main plastic extrusion molding machine to be extruded from the main plastic The molding machine co-extrudes the substrate layer 1 and the two side layers 2a and 2b sandwiched therein into an integrated product.

4. Finishing. The co-extruded composite product is rolled and shaped, covered with a protective film, and then cut into finished products.

In order to improve the qualified rate of products, the co-extrusion, shaping, and protective film coating process can be carried out in a closed 100,000-level purification area, and the light diffusing agent is in the shape of spherical or hemispherical particles. Preferably, for Example 2, the weight percentage of the light diffusing agent in the blend material used in the substrate layer 1 is 0.5% to 4%, and the rest is the base material; the weight content of the light diffusing agent contained in the side layers 2a and 2b is 0.5% % to 4%, the ultraviolet absorber is 0.1% to 0.2%, and the rest is the base material. For Example 3, the weight percentage of the light diffusing agent in the blend material used in the substrate layer 1 is 0.5% to 4%, and the rest is the base material; the weight content of the light diffusing agent contained in the side layers 2a and 2b is 0.5% to 4%. %, the ultraviolet absorber is 0.1% to 0.2%, and the rest is the base material.

From the three technical solutions of the present invention given above, it can be seen that under the premise of effectively ensuring good light permeability (transmittance) and uniformity, the diffusion plate has a strong ability to resist ultraviolet rays, and a good Dimensional stability and long service life. It adopts a multi-layer composite structure, that is, it is composed of two outer layers and a substrate layer sandwiched between the two outer layers. The substrate layer, the base material of the outer layer and the light diffusing agent are all transparent materials. Different rates of light refract, scatter, and reflect light passing through it, making the distribution of light uniform. Because both the substrate layer and the outer layer are blended layers containing a light diffusing agent, the structure of the present invention can obtain better light distribution uniformity than the structure of coating a diffusing film on a transparent substrate. By using polystyrene (PS) as the base material, the diffusion plate can have a higher light transmittance. At the same time, polystyrene has a small water absorption rate and is less affected by deformation caused by changes in environmental humidity, which can make the diffusion plate have better dimensional stability. The two outer layers contain ultraviolet absorbers, so that the diffusion plate has better anti-ultraviolet ability, reduces the yellowing of the plate caused by ultraviolet radiation, prolongs the service life of the diffusion plate, and can greatly reduce production costs. The invention has good implementation effect and expands the space for technical progress in the field.

Claims (8)

1, diffusion plate for backlight source of liquid crystal display, it is characterized in that: form layered composite structure by substrate layer and side layer at least, the side layer is two-layer, substrate layer is sandwiched in it, described substrate layer is that to adopt polystyrene be base material and the blended layer formed with light diffusing agent, and the side layer uses the blended layer of the transparent base that contains polyester and light diffusing agent and benzotriazole ultraviolet light absorber composition.

2, diffusion plate for backlight source of liquid crystal display according to claim 1 is characterized in that: the thickness range of described light diffusing sheet is 0.5mm～3mm, and the thickness in monolayer of described side layer is 0.04mm～0.06mm.

3, diffusion plate for backlight source of liquid crystal display according to claim 1 and 2 is characterized in that: described side layer is by the polymethylmethacrylate blended layer that to be base material form with light diffusing agent and benzotriazole ultraviolet light absorber.

4, diffusion plate for backlight source of liquid crystal display according to claim 3 is characterized in that: in the middle of the described substrate layer, the weight content of light diffusing agent is 0.5%～5%, and all the other are base material; In the middle of the described side layer, the weight content of light diffusing agent is 0.5%～5%, and the weight content of ultraviolet light absorber is 0.1%～0.3%, and all the other are base material.

5, diffusion plate for backlight source of liquid crystal display according to claim 1 and 2 is characterized in that: described side layer is by the polycarbonate blended layer that to be base material form with light diffusing agent and benzotriazole ultraviolet light absorber.

6, diffusion plate for backlight source of liquid crystal display according to claim 5 is characterized in that: in the middle of the described substrate layer, the weight content of light diffusing agent is 0.5%～4%, and all the other are base material; In the middle of the described side layer, the weight content of light diffusing agent is 0.5%～4%, and the weight content of ultraviolet light absorber is 0.1%～0.2%, and all the other are base material.

7, diffusion plate for backlight source of liquid crystal display according to claim 1 and 2 is characterized in that: described side layer is by polymethylmethacrylate and the styrol copolymer blended layer that to be base material form with light diffusing agent and benzotriazole ultraviolet light absorber.

8, diffusion plate for backlight source of liquid crystal display according to claim 7 is characterized in that: in the middle of the described substrate layer, the weight content of light diffusing agent is 0.5%～4%, and all the other are base material; In the middle of the described side layer, the weight content of light diffusing agent is 0.5%～4%, and the weight content of ultraviolet light absorber is 0.1%～0.2%, and all the other are base material.

Images