1. Field of the Invention
The present invention relates to a light guide module plate, and more particularly to a light guide module having a light diffusion arrangement over a light emitting surface, thereby providing uniform luminance distribution over the entire light emitting surface.
2. Description of Related Art
A liquid crystal display is capable of displaying a clear and sharp image over a wide area. It is thus used with various devices in which a message or picture needs to be illustrated. However, a liquid crystal itself does not emit light, therefore, it has to be back-lit by a light source to display the messages and/or pictures shown there.
In an ideal liquid crystal display, the backlight provides light evenly across the entire surface. In addition, the apparatus has to meet the requirements of being small in size, light in weight, and bright enough, while having a low power consumption.
U.S. Pat. No. 5,438,484 issued to Kanda et al. discloses a surface lighting device. A variety of prior art surface lighting devices are disclosed in
Kanda provides a solution, as shown in
Kanda provides another solution in
Aside from use of the “blueish light source”, it is noted that a “light curtain”, reference numeral 14 of
U.S. Pat. No. 5,881,201 issued to Khanarian discloses improved light pipes for backlighting liquid crystal display devices. The light pipes comprise transparent polymers with scattering centers. A preferred composition for such light pipes comprises a cycloolefin polymer containing scattering centers from suitable elastomers and inorganic fillers. The inventive light pipes offer superior scattering efficiency as well as spatial uniformity of scattering and uniformity of scattering across a wide wavelength range.
Referring to
The diffusion film 130 functions to homogenously diffuse the light beams projected from the light source 140. However, before the light beams reach the diffusion film 130, the light beams have to travel through the light guide 110, and be reflected by the reflective light enhancer 120. It should be noted that before the light beams reach the diffusion film 130, the light beams have to first be emitted from the light guide 110, and then must enter the diffusion film 130. The light guide 110 and the diffusion film 130 have different refractive indices and surely the energy of the light beam is exhausted during the transition. In addition, the diffusion film 130 is a separate element in addition to the light guide 110, has to be manufactured separately. As such, the overall cost is inevitably increased.
It is an object of the present invention to provide a light guide module in which a light diffusion arrangement is deployed over a light emitting surface of light guide module so as to reduce the overall cost.
In order to achieve the object set forth, a light guide module has a light emitting surface and a light incident surface orthogonal to the light emitting surface. A light diffusion arrangement is deployed on the light emitting surface and includes organic scattering balls homogenously mixed within a bonding agent. At least a light source is arranged adjacent the light guide to project light beams into the light guide module.
Referring to
Referring now to
Now referring to
As stated above, the use of the organic scattering balls 31 can effectively diffuse the light beams emitted from the emitting surface 21 so as to provide an evenly distributed luminance across the emitting surface 21. In addition, each of the scattering balls 31 has a limited surface contact with the emitting surface 21. As a result, the light losses resulting from the scattering balls can be controlled to with a certain limit. Accordingly, the overall optical characteristics of the light pipe 20 are enhanced.
It should be readily appreciated that the light pipe 20 can be embodied in a variety of forms. For example, a cross section of the light pipe can be a trapezoid configuration. In addition, the dot-web 41 can be arranged in different patterns based on its grain size and density. Typicahy, the grain size and density of the dot-web 41 can be increased in proportion to a distance from the incident surface 25, as shown in
Referring to
The light diffusion arrangement 30 made according to the present invention adequately addresses the prior art issue and provides a simple implementation over the light guide emitting surface 21 featuring less energy loss and brighter luminance.
Alternatively, a backlight module 50 can be embodied with two light sources 60 arranged adjacent two opposite ends (incident surfaces). When the second light source 60 is introduced, the overall luminance is further enhanced. In alternative embodiments, prism plates can be arranged adjacent to the light emitting surface 21 and/or the bottom surface 23.
The light guide module according to the present invention is made by the following steps, a) providing a light pipe 20 made from a dynthetic resin or glass; b) providing a mixture fully blended of the scattering balls 31 and bonding agent 33; c) deploying a layer of the mixture over an emitting surface 21 of the light pipe. The grain size of the scattering balls range from 10–50 micrometers, and material of the scattering balls selected from Polymethyl Methacrylate, Polycarbonate, and Methallocene Cyclic Olefin Copolymer. The method further comprises a step of forming a dot-web across the bottom surface of the light guide.
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
Number | Date | Country | Kind |
---|---|---|---|
91134012 | Nov 2002 | TW | national |
Number | Name | Date | Kind |
---|---|---|---|
5438484 | Kanda et al. | Aug 1995 | A |
5521797 | Kashima et al. | May 1996 | A |
5881201 | Khanarian | Mar 1999 | A |
6625379 | Azuma | Sep 2003 | B1 |
6825243 | Ohno et al. | Nov 2004 | B1 |
20040066645 | Graf et al. | Apr 2004 | A1 |
Number | Date | Country |
---|---|---|
08146418 | Jun 1996 | JP |
10197725 | Jul 1998 | JP |
Number | Date | Country | |
---|---|---|---|
20040228109 A1 | Nov 2004 | US |