Light guide plate and backlight module utilizing ultraviolet light source

A light guide plate comprises a light incidence surface for receiving light rays; a transforming fluorescent powder disposed on the light incidence surface for converting the light rays into white rays; a reflection surface for reflecting the light rays and destroying total internal reflection formed inside the light guide plate to generate planar light rays; a light emitting surface for emitting the planar light rays; and a lateral reflection surface disposed away from the light incidence surface for reflecting the light rays from the light incidence surface and the reflection surface; the lateral reflection surface having a compensative fluorescent powder disposed thereon for adjusting a color of the planar light rays. The light guide plate can reduce the backlight color difference for a panel of a single-end incident type to improve visual quality level and the quality of products.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a light guide plate and a backlight module, and more particularly, to a light guide plate and a backlight module utilizing an ultraviolet light source capable of reducing backlight color difference caused by light incidence at a single end.

BACKGROUND OF THE INVENTION

In a sidelight-type backlight module, a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED) is currently adopted for serving as a light source. To satisfy the requirement of developing thinning devices, a large scale backlight module has been gradually designed to be incident by light rays at a single end. The single-end incident type becomes a design tendency as the emitting efficiency of the light source is improved. However, there are problems accompanied as well.FIG. 1is a schematic diagram showing a structure of a conventional light guide plate. The light guide plate100shown inFIG. 1comprises a light incidence surface101, a reflection surface102, a light emitting surface102, and a lateral reflection surface104. The light source110inFIG. 1is an ultraviolet light source. After the light rays emitted from the light source110enters the light guide plate100via the light incidence surface101, the light rays are converted to white rays by a transforming fluorescent powder111, wherein the transforming fluorescent powder111is a mixture of a yellow-ray fluorescent powder and a blue-ray fluorescent powder. The total internal reflection formed by the converted white rays is then destroyed by optical microstructures105on the reflection surface102and the rays are emitted from the light emitting surface103. However, when the light rays are propagated in the light guide plate, the light rays encountering the optical microstructures105will be scattered for each collision and at the same time a part of energy of the light rays will be absorbed. Therefore, the spectrum of the light rays will be changed for each time the light rays are scattered. When the light rays are propagated from an end of the light guide plate100to the other end, the color of the light rays is gradually altered. In the conventional sidelight-type backlight module, the optical microstructures105of the light guide plate100can be formed into a printed type and a non-printed type. An ink on the printed-type optical microstructures105mainly absorbs short-wavelength light rays emitted from the light source110, and therefore a color degree of the light rays will become large (that is, the color will deviate to a yellow color) when the light rays are propagated to an end away from the light incidence surface101. A panel color difference will be occurred eventually. That is, the color of respective points is non-uniform at a backlight side. The bigger is the size of the light guide plate, more apparent is the color difference. This may seriously affect visual quality level and the quality of products. The non-printed-type light guide plate is a light guide plate adopting microstructures made of methylmethacrylate styrene (MS) or other materials. The MS material or the other material itself will absorb short-wavelength light rays and will cause the panel color difference as well.

Therefore, it is necessary to provide a light guide plate and a backlight module utilizing an ultraviolet light source for solving the problems in the conventional skills.

SUMMARY OF THE INVENTION

The main objective of the present invention is to provide a light guide plate and a backlight module utilizing an ultraviolet light source for solving the problem of non-uniform color of respective points on a backlight side.

The technical schemes provided in the present invention are described below.

A light guide plate, comprising:

a light incidence surface for receiving light rays; a transforming fluorescent powder disposed at a side of the light incidence surface for converting the light rays into white rays; a reflection surface for reflecting the light rays received by the light incidence surface and destroying total internal reflection formed inside the light guide plate, by the light rays received by the light incidence surface, to generate planar light rays; a light emitting surface for emitting the planar light rays; and a lateral reflection surface disposed away from an end of the light incidence surface for reflecting the light rays coming from the light incidence surface and the reflection surface;

the lateral reflection surface has a compensative fluorescent powder disposed thereon for adjusting a color of the planar light rays emitted from the light emitting surface;

the compensative fluorescent powder is doped in a body of the lateral reflection surface; or

the lateral reflection surface has a transparent film attached at an inner side of the lateral reflection surface and the transparent film is coated with the compensative fluorescent powder; or

the lateral reflection surface has the transparent film attached at the inner side of the lateral reflection surface and the compensative fluorescent powder is doped in the transparent film;

the lateral reflection surface has at least one angle formed thereon.

The present invention also provides a light guide plate, said light guide plate comprising: a light incidence surface for receiving light rays; a transforming fluorescent powder disposed at a side of the light incidence surface for converting the light rays into white rays; a reflection surface for reflecting the light rays received by the light incidence surface and destroying total internal reflection formed inside the light guide plate, by the light rays received by the light incidence surface, to generate planar light rays; a light emitting surface for emitting the planar light rays; and a lateral reflection surface disposed away from an end of the light incidence surface for reflecting the light rays coming from the light incidence surface and the reflection surface; the lateral reflection surface has a compensative fluorescent powder disposed thereon for adjusting a color of the planar light rays emitted from the light emitting surface.

The present invention further provides a backlight module, said backlight module comprising a light guide plate and an ultraviolet light source, said light guide plate comprising: a light incidence surface for receiving light rays; a transforming fluorescent powder disposed at a side of the light incidence surface for converting the light rays into white rays; a reflection surface for reflecting the light rays received by the light incidence surface and destroying total internal reflection formed inside the light guide plate, by the light rays received by the light incidence surface, to generate planar light rays; a light emitting surface for emitting the planar light rays; and a lateral reflection surface disposed away from an end of the light incidence surface for reflecting the light rays coming from the light incidence surface and the reflection surface; the lateral reflection surface having a compensative fluorescent powder disposed thereon for adjusting a color of the planar light rays emitted from the light emitting surface; the light source being disposed at a side of the light incidence surface of the light guide plate for emitting the light rays toward the light incidence surface.

In one embodiment of the present invention, the compensative fluorescent powder is doped in a body of the lateral reflection surface and/or the transforming fluorescent powder is doped in a body of the light incidence surface.

In one embodiment of the present invention, the lateral reflection surface has a transparent film attached at an inner side of the lateral reflection surface and the transparent film is coated with the compensative fluorescent powder; and/or the light incidence surface has a transparent film attached at an inner side of the light incidence surface and the transparent film is coated with the transforming fluorescent powder.

In one embodiment of the present invention, the lateral reflection surface has a transparent film attached at an inner side of the lateral reflection surface and the compensative fluorescent powder is doped in the transparent film; and/or the light incidence surface has a transparent film attached at an inner side of the light incidence surface and the transforming fluorescent powder is doped in the transparent film.

In one embodiment of the present invention, the compensative fluorescent powder comprises a blue-ray fluorescent powder; the transforming fluorescent powder comprises a yellow-ray fluorescent powder and a blue-ray fluorescent powder.

In one embodiment of the present invention, the lateral reflection surface has at least one angle formed thereon.

In one embodiment of the present invention, the light guide plate is a light guide plate having microstructures made of methylmethacrylate styrene (MS).

In one embodiment of the present invention, the light emitting surface has a brightness enhancement film disposed at a side of the light emitting surface for increasing light emitting efficiency,

In one embodiment of the present invention, the reflection surface has a reflecting unit disposed at a side of the reflection surface for increasing light reflecting efficiency.

Compared to the conventional light guide plate and backlight module of a single-end incident type, the light guide plate and backlight module of the present invention utilizes the compensative fluorescent powder to be coated on the lateral reflection surface of the light guide plate so as to reduce the backlight color difference for a panel of the single-end incident type to achieve a better visual quality level and improve the quality of products.

DETAILED DESCRIPTION OF THE INVENTION

The following descriptions for the respective embodiments are specific embodiments capable of being implemented for illustrations of the present invention with referring to appended figures. For example, the terms of up, down, front, rear, left, right, interior, exterior, side, etcetera are merely directions of referring to appended figures. Therefore, the wordings of directions are employed for explaining and understanding the present invention but not limitations thereto.

FIG. 2is a schematic diagram showing a structure of a light guide plate in accordance with a first preferred embodiment of the present invention. Referring toFIG. 2, the backlight module of the present invention is a sidelight-type backlight module. The backlight module comprises a light guide plate200and a light source210. The light source210is an ultraviolet light source, for example, a cold cathode fluorescent lamp (CCFL), a light emitting diode (LED), an organic light emitting diode (OLED), an electro-luminescence (EL) component, and any combination of above light sources. The light guide plate200comprises a light incidence surface201, a reflection surface202, a light emitting surface203, and a lateral reflection surface204. The light incidence surface201is utilized for receiving light rays; the reflection surface202is utilized for reflecting the light rays received by the light incidence surface201and destroying total internal reflection formed inside the light guide plate200, by the light rays received by the light incidence surface201, to generate planar light rays; the light emitting surface203is utilized for emitting the planar light rays; the lateral reflection surface204is disposed away from an end of the light incidence surface201for reflecting the light rays coming from the light incidence surface201and the reflection surface202; a transforming fluorescent powder211is disposed at a side of the light incidence surface201for converting the light rays into white rays; the lateral reflection surface204has a compensative fluorescent powder206disposed thereon for adjusting a color of the planar light rays emitted from the light emitting surface203.

The light guide plate and backlight module of the present invention is to solve the problem of backlight color difference caused by light incidence at a single end in the conventional light guide plate and backlight module. In the schematic structure diagram of the light guide plate as shown inFIG. 2in accordance with the first preferred embodiment of the present invention, the lateral reflection surface204of the light guide plate200is coated with the compensative fluorescent powder206. The compensative fluorescent powder206is mainly a fluorescent powder capable of exciting light rays and generating short-wavelength light rays such that a larger amount of short-wavelength light rays will be generated when the light rays passed over encounter the compensative fluorescent powder206. The short-wavelength light rays are then reflected back to compensate a part of short-wavelength light rays absorbed by an ink of optical microstructures205. A color compensation manner is utilized such that the color of the emitted light rays away from the light source210is compensated.

For a preferred embodiment of the present invention, the compensative fluorescent powder206can be doped in a body of the lateral reflection surface204. That is, based on a predetermined proportion, the compensative fluorescent powder206is mixed into a plastic material or other material used for manufacturing the body of the lateral reflection surface204, and is distributed in the body of the lateral reflection surface204by an injection molding manner. It also can utilize a transparent film to attach at an inner side of the lateral reflection surface204. The transparent film is coated with the compensative fluorescent powder206or the compensative fluorescent powder206is doped in the transparent film. The coating manner can be implemented by mixing the compensative fluorescent powder206into a chemical solvent and then spraying the chemical solvent on the lateral reflection surface204by an ink-jetting manner or directly coating the compensative fluorescent powder206on the transparent film. The manner for doping the compensative fluorescent powder206in the transparent film can be implemented by mixing the compensative fluorescent powder206and a transparent material by a heat treatment such that a doped film is formed after cooling. As desired, a user can choose an appropriate manner to dispose the compensative fluorescent powder206on the lateral reflection surface204. The above manners also can be adopted to dispose the transforming fluorescent powder211on a side of the light incident surface.

At present, the ink on the optical microstructures205mainly absorbs short-wavelength light rays that are emitted from the light source210. Therefore, for a preferred embodiment of the present invention, the adopted compensative fluorescent powder206comprises a blue-ray fluorescent powder such that a larger amount of short-wavelength light rays will be generated when the light rays passed over encounter the blue-ray fluorescent powder. The short-wavelength light rays are then reflected back to compensate a part of short-wavelength light rays absorbed by the ink of the optical microstructures205. A color compensation manner is utilized such that the color of the emitted light rays away from the light source210is compensated. The compensative fluorescent powder206coated on the lateral reflection surface204can be adjusted to different proportions according to different sizes of the light guide plate. When the size of the light guide plate210with single-end incidence is bigger, it needs to dispose more blue-ray fluorescent powder to compensate short-wavelength light rays. Otherwise, the light rays go further when the light guide plate210is bigger, and the color difference of panel will become more serious. The transforming fluorescent powder mainly comprises a yellow-ray fluorescent powder and a blue-ray fluorescent powder, and their corresponding proportion can be set according to the wavelengths emitted by the ultraviolet light source for generating the required white rays.

Above all, it belongs to the protective scope of the present invention as long as the lateral reflection surface204has the compensative fluorescent powder206disposed thereon for reducing the backlight color difference for a panel of the single-end incident type, no matter what manner is adopted to dispose the compensative fluorescent powder206on the lateral reflection surface204.

FIG. 3is a schematic diagram showing a structure of a light guide plate in accordance with a second preferred embodiment of the present invention. The light guide plate300comprises a light incidence surface301, a reflection surface302, a light emitting surface303, and a lateral reflection surface304. The light incidence surface301is utilized for receiving light rays; the reflection surface302is utilized for reflecting the light rays received by the light incidence surface301and destroying total internal reflection formed inside the light guide plate300, by the light rays received by the light incidence surface301, to generate planar light rays; the light emitting surface303is utilized for emitting the planar light rays; the lateral reflection surface304is disposed away from an end of the light incidence surface301for reflecting the light rays coming from the light incidence surface301and the reflection surface302; a transforming fluorescent powder311is disposed at a side of the light incidence surface301for converting the light rays into white rays; the lateral reflection surface304has a compensative fluorescent powder306disposed thereon for adjusting a color of the planar light rays emitted from the light emitting surface303. Further, the lateral reflection surface304has at least one angle307formed thereon. As can be deduced from a law of reflection, the deflected angle of a light ray will be large when the angle307is small; the deflected angle of a light ray will be small when the angle307is large. By angular designs of the light incidence surface301, the reflection surface302, the light emitting surface303, and the lateral reflection surface304on the light guide plate300, particularly by the angle307designed on the lateral reflection surface304, the emitting angle of light rays can be effectively adjusted and thereby increasing the light emitting efficiency of the light guide plate300. The design of the angle, such as number, shape, and etc. can be altered according to the light emitting efficiency, and the present invention is not limited thereto. It belongs to the protective scope of the present invention as long as the lateral reflection surface304has the compensative fluorescent powder306disposed thereon for reducing the backlight color difference for a panel of the single-end incident type. The light emitting surface303has a brightness enhancement film308disposed at a side of the light emitting surface303for increasing the light emitting efficiency. The reflection surface302has a reflecting unit309disposed at a side of the reflection surface302for increasing the light reflecting efficiency. As shown inFIG. 3, the reflecting unit309is used to reflect the light rays downwardly penetrating the light guide plate300back to the light guide plate300for increasing the utilization rate of light rays. The brightness enhancement film308is disposed at a side of the light emitting surface303for increasing the light emitting efficiency of the light guide plate300.

In the second preferred embodiment of the present invention, the compensative fluorescent powder306can be doped in a body of the lateral reflection surface304. That is, based on a predetermined proportion, the compensative fluorescent powder306is mixed into a plastic material or other material used for manufacturing the body of the lateral reflection surface304, and is distributed in the body of the lateral reflection surface304by an injection molding mariner. It also can utilize a transparent film to attach at an inner side of the lateral reflection surface304. The transparent film is coated with the compensative fluorescent powder306or the compensative fluorescent powder306is doped in the transparent film. The coating manner can be implemented by mixing the compensative fluorescent powder306into a chemical solvent and then spraying the chemical solvent on the lateral reflection surface304by an ink-jetting manner or directly coating the compensative fluorescent powder306on the transparent film. The manner for doping the compensative fluorescent powder306in the transparent film can be implemented by mixing the compensative fluorescent powder306and a transparent material by a heat treatment such that a doped film is formed after cooling. As desired, a user can choose an appropriate manner to dispose the compensative fluorescent powder306on the lateral reflection surface304. The above manners also can be adopted to dispose the transforming fluorescent powder311on a side of the light incident surface.

For the preferred embodiment of the present invention, the light guide plate is a light guide plate having microstructures made of methylmethacrylate styrene (MS). The light guide plate of the present invention can be implemented by a light guide plate made of other non-printed type of materials, such as a light guide plate having MS microstructures. The main reason why the light guide plate having the MS material causes the color difference is that the MS material itself will absorb short-wavelength light rays. Therefore, for this instance, the structure of the light guide plate of the present invention also can be utilized to solve the color difference in a panel and improve the visual quality level and the quality of products.

The present invention also relates to a backlight module. The backlight module comprises a light guide plate and an ultraviolet light source. The light guide plate comprises a light incidence surface for receiving light rays; a transforming fluorescent powder disposed at a side of the light incidence surface for converting the light rays into white rays; a reflection surface for reflecting the light rays received by the light incidence surface and destroying total internal reflection formed inside the light guide plate, by the light rays received by the light incidence surface, to generate planar light rays; a light emitting surface for emitting the planar light rays; and a lateral reflection surface disposed away from an end of the light incidence surface for reflecting the light rays coming from the light incidence surface and the reflection surface; the lateral reflection surface having a compensative fluorescent powder disposed thereon for adjusting a color of the planar light rays emitted from the light emitting surface; the ultraviolet light source being disposed at a side of the light incidence surface of the light guide plate for emitting the light rays toward the light incidence surface.

While the preferred embodiments of the present invention have been illustrated and described in detail, various modifications and alterations can be made by persons skilled in this art. The embodiment of the present invention is therefore described in an illustrative but not restrictive sense. It is intended that the present invention should not be limited to the particular forms as illustrated, and that all modifications and alterations which maintain the spirit and realm of the present invention are within the scope as defined in the appended claims.