CN101153925A - Optical sheet, method for manufacturing same, backlight module and liquid crystal display device - Google Patents

Abstract

An optical sheet is suitable for being matched with a plurality of light sources to provide a surface light source. The optical plate comprises a light-transmitting substrate and a plurality of light scattering particles. The light-transmitting substrate is arranged beside the light sources, the light scattering particles are arranged in the light-transmitting substrate, and the distribution density of the light scattering particles is changed along with the distance from the light sources. In addition, the invention also provides a manufacturing method of the optical sheet, a backlight module with the optical sheet and a liquid crystal display device with the backlight module.

Description

Optical plate, manufacturing method thereof, backlight module, and liquid crystal display device

technical field

The present invention relates to an optical plate and a manufacturing method thereof, in particular to an optical plate used in a backlight module, a manufacturing method thereof and a backlight module using the optical plate.

Background technique

With the advancement of technology, the volume of video or image devices is becoming thinner and lighter. Therefore, flat-panel displays developed in conjunction with optoelectronic technology and semiconductor manufacturing technology, such as liquid crystal displays (LCDs), organic light-emitting displays (OLEDs) or plasma displays (PDPs), have gradually become the mainstream of display products, and among them, liquid crystal displays It is the mainstream of display products at present.

It is worth noting that since the liquid crystal display panel itself does not emit light, the surface light source required by the liquid crystal display panel must be provided by means of the backlight module, so that the liquid crystal display can achieve the display effect and obtain sufficient brightness and contrast at the same time. Therefore, the design of the backlight module is good enough to affect the display quality of the liquid crystal display.

FIG. 1A shows a schematic structural diagram of a known backlight module and a diagram of the relationship between the brightness and the position of the surface light source provided. Please refer to FIG. 1A , a known backlight module 100a is a direct type backlight module, which includes a light box 110a, a diffusion plate 130a and a plurality of light sources 120a. These light sources 120a are cold cathode fluorescent tubes, which are arranged at the bottom of the light box 110a at a proper distance, and the diffusion plate 130a is arranged at the light emitting section 112a of the light box 110a. The light emitted by these light sources 120a, after passing through the diffusion plate 130a, will form a surface light source as the light source required by the liquid crystal display panel.

The known diffusion plate 130a has a plurality of light scattering particles 132a to achieve the effect of uniformly diffusing light. Specifically, the known diffuser plate 130a is manufactured by injection molding, and its material is usually plastic, such as polycarbonate (polycarbonate, PC), and the light scattering particles 132a are doped in the plastic material. Therefore, after the diffusion plate 130a is molded, the light scattering particles 132a will be contained inside, and the light scattering particles 132a are evenly distributed in the diffusion plate 130a. When the light emitted by the light source 120a is incident on the diffusion plate 130a, most of the light will be scattered by the light scattering particles 132a to achieve a diffusion effect.

However, because the portion of the surface light source provided by the known backlight module 100a located above the light source 120a is brighter than the rest, and the luminance is quite different, the uniformity of the surface light source is poor.

FIG. 1B and FIG. 1C are structural schematic diagrams of another two known backlight modules and the relationship between the brightness and the position of the surface light source provided. Please refer to FIG. 1B first. In order to improve the above phenomenon of poor uniformity of the surface light source, in the known backlight module 100b, a diffusion plate 130b with a higher distribution density of light scattering particles 132b is used. Wherein, because the distribution density of the light scattering particles 132b is high, the light transmittance provided by the light source 120b is relatively low, so although the brightness difference between the part above the light source 120b and the rest of the surface light source can be improved to improve the uniformity of the surface light source , but it also reduces the overall brightness of the surface light source.

Please refer to FIG. 1C, in order to improve the poor uniformity of the surface light source provided by the backlight module 100a, in the known backlight module 100c, because the distance between the light source 120c at the bottom of the light box 110c and the diffusion plate 130c is relatively long, There is enough distance between the light source 120c and the diffuser plate 130c to diffuse the light, so the uniformity of the surface light source is better. However, the long distance between the light source 120c and the diffusion plate 130c means that the thickness of the backlight module 100c will increase, which is contrary to the current trend of liquid crystal displays requiring thinner and lighter.

Contents of the invention

The purpose of the present invention is to provide an optical plate suitable for matching with a light source group to provide a surface light source capable of both brightness and uniformity.

Another object of the present invention is to provide a backlight module, which can take into account the brightness and uniformity of the surface light source without increasing the overall thickness.

Another object of the present invention is to provide a liquid crystal display device, which can display images with better brightness and uniformity without increasing the overall thickness.

Yet another object of the present invention is to provide a method for manufacturing an optical plate to form a plurality of blocks with different distribution densities of light-scattering particles in a light-transmitting substrate.

Based on the above and other objectives, the present invention provides an optical plate suitable for matching with a plurality of light sources to provide a surface light source. The optical plate includes a light-transmitting substrate arranged beside the light source, and a plurality of light-scattering particles arranged in the light-transmitting substrate. The distribution density of the light scattering particles varies with the distance from the plurality of light sources.

The present invention also provides a backlight module, which includes a plurality of light sources and an optical plate disposed beside the light sources. The optical plate includes a light-transmitting substrate and a plurality of light-scattering particles arranged in the light-transmitting substrate. Wherein, the distribution density of the light-scattering particles varies with the distance from the multiple light sources.

The present invention also proposes a liquid crystal display device, which includes a liquid crystal display panel and the backlight module. Wherein, the backlight module is arranged beside the liquid crystal display panel to provide display light source required by the liquid crystal display panel.

According to an embodiment of the present invention, the transparent substrate is, for example, divided into a plurality of first blocks located above each light source, and a plurality of second blocks located between two adjacent first blocks, and each of the first blocks The distribution density of the light-scattering particles in one block is greater than the distribution density of the light-scattering particles in each second block.

According to an embodiment of the present invention, the light source includes a cold cathode fluorescent tube or an array of light emitting diodes.

According to an embodiment of the present invention, the refractive index of the light scattering particles is different from that of the transparent substrate.

According to an embodiment of the present invention, the optical plate is, for example, a diffuser plate or a light guide plate.

According to a preferred embodiment of the present invention, the light-scattering particles are, for example, particles formed by irradiating a light-transmitting substrate with a laser beam.

According to an embodiment of the present invention, the backlight module further includes an optical film disposed on the optical plate. In addition, the optical film is, for example, a diffusion film, a brightness enhancement film or a combination of both.

The present invention also proposes a method for manufacturing an optical plate, which includes the following steps: firstly, a light-transmitting substrate is provided. Then, the light-transmitting substrate is irradiated with laser beams to form a plurality of light-scattering particles in the light-transmitting substrate.

In the manufacturing method of the optical plate, the method of forming the light scattering particles is, for example, irradiating different positions of the light-transmitting substrate with laser beams to form a plurality of blocks with different distribution densities of the light-scattering particles in the light-transmitting substrate.

In the manufacturing method of the optical plate, the laser beam is, for example, Nd-YAG laser.

According to an embodiment of the present invention, the material of the transparent substrate is, for example, plastic materials such as polycarbonate, polystyrene (PS) or polymethylmethacrylate (PMMA).

Based on the above, in the optical sheet of the present invention, since the distribution density of light scattering particles varies with the distance from the light source, the backlight module using this optical sheet can take into account the surface area without increasing the overall thickness. The brightness and uniformity of the light source. Therefore, the liquid crystal display device with the backlight module can display images with better brightness and uniformity without increasing the overall thickness. In addition, the manufacturing method of the optical plate of the present invention uses laser beams to irradiate the light-transmitting substrate to form light-scattering particles, so the distribution density of light-scattering particles in different regions in the light-transmitting substrate can be controlled.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments are specifically cited below, together with the accompanying drawings, and are described in detail as follows.

Description of drawings

FIG. 1A shows a schematic structural diagram of a known backlight module and a diagram of the relationship between the brightness and the position of the surface light source provided;

FIG. 1B and FIG. 1C show the structural schematic diagrams of two other known backlight modules and the relationship between the brightness and the position of the surface light source provided;

2 is a schematic diagram of a backlight module according to a preferred embodiment of the present invention;

3 is a schematic structural view of a liquid crystal display device according to an embodiment of the present invention;

FIG. 4A to FIG. 4C show a flow chart of the steps of the manufacturing method of the optical plate according to the embodiment of the present invention.

Detailed ways

The invention provides an optical plate, which is suitable for matching with multiple light sources to provide a surface light source. The optical plate includes a light-transmitting substrate arranged beside the light source, and a plurality of light-scattering particles arranged in the light-transmitting substrate. The distribution density of these light scattering particles varies with the distance from the light source. In order to clearly explain the present invention, the following backlight module is specifically used as an embodiment for illustration, but it is not intended to limit aspects of the present invention.

Fig. 2 shows a schematic diagram of a backlight module according to a preferred embodiment of the present invention. Please refer to FIG. 2 , the backlight module 200 is, for example, a direct type backlight module, which includes a light box 210 having a light emitting section 212 , a plurality of light sources 220 and an optical plate 230 . Wherein, the light sources 220 are disposed at the bottom of the light box 210 at an appropriate distance, and the light emitting section 212 is located above the light box 210 . The optical plate 230 includes a light-transmitting substrate 232 disposed at the light emitting section 212 of the light box 210 , and a plurality of light-scattering particles 234 disposed in the light-transmitting substrate 232 . The transparent substrate 232 is divided into a plurality of first blocks 236 located above the light source 220, and a plurality of second blocks 238 located between two adjacent first blocks 236, and the light in each first block 236 The distribution density of the scattering particles 234 is greater than the distribution density of the light scattering particles 234 in each second block 238 .

When the light provided by the light source 220 enters the optical plate 230 from the light exit section 212 of the light box 210, since the distribution density of the light scattering particles 234 in the first block 236 is relatively high, the light entering the first block 236 The light is easily scattered to the second block 238 adjacent to the first block 236, so the transmittance of the light in the first block 236 above the light source 220 is low, which can reduce the surface area provided by the backlight module 200. The brightness of the portion of the light source located above the light source 220 . On the other hand, when light enters into the second block 238 , since the distribution density of the light scattering particles 234 in the second block 238 is low, the transmittance of the light is relatively high. In this way, the brightness difference between the surface light source provided by the backlight module 200 above the light source 220 and the rest can be reduced, so the uniformity of the surface light source provided by the backlight module 200 is better.

In addition, compared with the known backlight module 100b (as shown in FIG. 1B ), in the backlight module 200 of this embodiment, the distribution density of the light scattering particles 234 in the second block 238 is lower, so that the second block 238 has a high light transmittance, so it can improve the brightness of the surface light source. In addition, since the distance between the light source 220 and the optical plate 230 does not need to be increased in the backlight module 200, a surface light source with better uniformity can be provided without increasing the overall thickness, so that the liquid crystal display device conforms to the requirements of current electronic products. Pursue the trend of thin and short.

In a preferred embodiment of the present invention, in order to further improve the uniformity of the surface light source, an optical film 240 can be disposed on the optical plate 230 . The optical film 240 is, for example, a diffusion film, an enhancement film or a combination of both. In addition, the light source 220 used in the backlight module 200 in this embodiment may be a CCFL or an LED array. The material of the transparent substrate 232 is, for example, a plastic material such as polycarbonate, polystyrene or polymethyl methacrylate.

FIG. 3 is a schematic structural view of a liquid crystal display device according to an embodiment of the present invention. Referring to FIG. 3 , the liquid crystal display device 300 of this embodiment includes a liquid crystal display panel 310 and a backlight module 320 disposed beside the liquid crystal display panel 310 . Wherein, the backlight module 320 is used to provide the display light source required by the liquid crystal display panel 310 . In addition, the liquid crystal display panel 310 includes, for example, an upper substrate 312 , a lower substrate 314 , and a liquid crystal layer 316 disposed between the upper substrate 312 and the lower substrate 314 . The backlight module 320 is, for example, the backlight module 200 shown in FIG. 2 or a side-illuminated backlight module in which the distribution density of light scattering particles in the diffuser varies with the distance from the light source group.

Since the backlight module 320 can provide a surface light source with better uniformity without increasing the overall thickness, the liquid crystal display device 300 can display images with better brightness and uniformity without increasing the overall thickness.

The present invention also proposes a manufacturing method of the optical plate to realize the above-mentioned diffuser plate in which the distribution density of the light scattering particles can vary with the distance from the light source group. The manufacturing method of the optical plate will be introduced in detail below.

FIG. 4A to FIG. 4C show a flow chart of the steps of the manufacturing method of the optical plate according to the embodiment of the present invention. Please refer to FIG. 4A to FIG. 4C, the manufacturing method of the optical plate of this embodiment includes the following steps:

First, as shown in FIG. 4A , a light-transmitting substrate 410 is provided, which is made of plastic materials such as polycarbonate or polymethyl methacrylate.

Next, as shown in FIG. 4B , the light-transmitting substrate 410 is irradiated with a laser beam 50 to form light-scattering particles in the light-transmitting substrate 410 . More specifically, in this implementation, for example, the laser beam 50 is focused on a specific position in the transparent substrate 410, and the high energy of the laser beam 50 causes the material structure of the specific position in the transparent substrate 410 to change, such as forming The refractive index is different from the local small-scale structure of the raw material of the light-transmitting substrate 410 , thereby forming light scattering particles 420 that can partially refract and partially reflect light. Afterwards, the above-mentioned actions are repeated to irradiate multiple different positions of the transparent substrate 410 with the laser beam 50 , thereby forming multiple light scattering particles 420 , and completing the fabrication of the optical plate 400 (as shown in FIG. 4C ).

The distribution position of the light-scattering particles 420 can be controlled by using the laser beam 50 with an appropriate wavelength and focusing on a specific position in the transparent substrate 410 . The laser selected in this embodiment is an ultrashort pulse laser, such as Nd-YAG laser. In addition, in this embodiment, multiple laser beams 50 can be used to irradiate or focus on different positions of the transparent substrate 410 at the same time, so as to form multiple light scattering particles 420 at the same time, thereby improving the production efficiency of the optical plate 400, or using The program-controlled laser processing machine can be used for accurate and rapid control, which can also improve the production efficiency of the optical plate 400 .

The advantage of the manufacturing method of the optical plate in this embodiment is that during the manufacturing process, by changing the focus of the laser beam in the light-transmitting substrate, the generation position of the light-scattering particles in the light-transmitting substrate can be controlled, so it can be accurately The distribution density of the light-scattering particles in different regions of the transparent substrate is controlled to form the optical plate 230 as shown in FIG. 2 .

It is worth mentioning that the manufacturing method of the optical plate of this embodiment can also be applied to control the distribution density of the light scattering particles forming the desired specific area in the light guide plate or in other optical plates.

To sum up, the optical plate, its manufacturing method and backlight module of the present invention have at least the following advantages:

1. In the optical plate of the present invention, since the distribution density of light scattering particles varies with the distance from the light source, the backlight module using this optical plate can take into account the surface light source without increasing the overall thickness. Brightness and uniformity to improve the display quality of liquid crystal display devices.

2. Since the thickness of the backlight module of the present invention will not increase, the overall thickness of the liquid crystal display device will not increase, which can make the liquid crystal display device conform to the current trend of pursuing light, thin and short electronic products.

3. The manufacturing method of the optical plate of the present invention uses laser beams to irradiate the light-transmitting substrate to form light-scattering particles, so the distribution density of light-scattering particles in different sections of the light-transmitting substrate can be precisely controlled.

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any skilled person may make some modifications and changes without departing from the spirit and scope of the present invention. Therefore, the protection of the present invention The scope is to be determined as defined by the appended claims.

Claims (20)

1. an optical plate is suitable for and a plurality of light source collocation, and so that area source to be provided, described optical plate comprises:

Transparent substrates is disposed at by described a plurality of light source; And

A plurality of light diffusing particles are disposed in the described transparent substrates, and the distribution density of wherein said a plurality of light diffusing particles is with the distance of described a plurality of light sources different variations being arranged.

2. optical plate as claimed in claim 1, wherein said transparent substrates is divided into a plurality of first blocks that are positioned at described a plurality of light sources top, and a plurality of second blocks between adjacent two first blocks, and the distribution density of the described a plurality of light diffusing particles in each described first block is greater than the distribution density of the described a plurality of light diffusing particles in each described second block.

3. optical plate as claimed in claim 1, the refractive index of wherein said a plurality of light diffusing particles is different with the refractive index of described transparent substrates.

4. optical plate as claimed in claim 1, wherein said a plurality of light diffusing particles comprise with the formed particle of the described transparent substrates of laser beam irradiation.

5. optical plate as claimed in claim 1 is diffuser plate.

6. backlight module comprises:

A plurality of light sources;

Optical plate is disposed at by described a plurality of light source, and described optical plate comprises:

Transparent substrates; And

A plurality of light diffusing particles are disposed in the described transparent substrates, and the distribution density of wherein said a plurality of light diffusing particles is with the distance of described a plurality of light sources different variations being arranged.

7. backlight module as claimed in claim 6, wherein said transparent substrates is divided into a plurality of first blocks that are positioned at described a plurality of light sources top, and a plurality of second blocks between adjacent two first blocks, and the distribution density of the described a plurality of light diffusing particles in each described first block is greater than the distribution density of the described a plurality of light diffusing particles in each described second block.

8. backlight module as claimed in claim 6, the refractive index of wherein said a plurality of light diffusing particles is different with the refractive index of described transparent substrates.

9. backlight module as claimed in claim 6, wherein said a plurality of light diffusing particles comprise with the formed particle of the described transparent substrates of laser beam irradiation.

10. backlight module as claimed in claim 6, wherein said optical plate are diffuser plate.

11. backlight module as claimed in claim 6 also comprises blooming piece, is disposed on the described optical plate.

12. backlight module as claimed in claim 11, wherein said blooming piece comprise diffusion sheet, brightening piece or both combinations.

13. a liquid crystal indicator comprises:

Display panels;

Backlight module is disposed at by the described display panels, and to provide described display panels required display light source, described backlight module comprises:

A plurality of light sources;

Optical plate is disposed at by described a plurality of light source, and described optical plate comprises:

Transparent substrates; And

A plurality of light diffusing particles are disposed in the described transparent substrates, and the distribution density of wherein said a plurality of light diffusing particles is with the distance of described a plurality of light sources different variations being arranged.

14. liquid crystal indicator as claimed in claim 13, wherein said transparent substrates is divided into a plurality of first blocks that are positioned at described a plurality of light sources top, and a plurality of second blocks between adjacent two first blocks, and the distribution density of the described a plurality of light diffusing particles in each described first block is greater than the distribution density of the described a plurality of light diffusing particles in each described second block.

15. liquid crystal indicator as claimed in claim 13, the refractive index of wherein said a plurality of light diffusing particles is different with the refractive index of described transparent substrates.

16. liquid crystal indicator as claimed in claim 13, wherein said a plurality of light diffusing particles comprise with the formed particle of the described transparent substrates of laser beam irradiation.

17. liquid crystal indicator as claimed in claim 13, wherein said optical plate are diffuser plate.

18. liquid crystal indicator as claimed in claim 13, wherein said backlight module also comprises blooming piece, is disposed on the described optical plate.

19. the manufacture method of an optical plate comprises:

Transparent substrates is provided; And

With the described transparent substrates of laser beam irradiation, in described transparent substrates, to form a plurality of light diffusing particles.

20. the manufacture method of optical plate as claimed in claim 19, the method that wherein forms described a plurality of light diffusing particles comprises the diverse location with the described transparent substrates of laser beam irradiation, to form the different a plurality of blocks of described a plurality of light diffusing particles distribution densities in described transparent substrates.

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