Patent Application
20100301504
1. Field of the Invention
The present invention relates to light-guiding modules and more particularly, to a method of making a light-guiding module, which enables a reflector and a light guide plate to be made integrally.
2. Description of the Related Art
A backlight unit for a liquid crystal display (hereinafter referred to as “LCD”) generally comprises a light source, a light guide plate, a reflector, a diffuser, a brightness enhancement film and a polarization converter. The light guide plate is adapted for guiding the direction of incident light, enhancing the luminance of the liquid crystal panel and controlling the brightness distribution uniformly. The reflector is adapted for avoiding leakage of light through the bottom side of the light guide plate, enhancing the efficiency of use of incident light. The diffuser is adapted for diffusing the light passing through the light guide plate to a uniform surface light.
A conventional backlight unit has the aforesaid component parts assembled together in proper order. Because a gap is inevitably left between each two adjacent component parts, a part of the light going from one component part to another will be reflected or refracted, lowering the luminous efficiency of the backlight unit. More particularly, the diffusion structure at the bottom side of the light guide plate makes the bottom side of the light guide plate uneven, resulting in a big gap between the light guide plate and the reflector and worsening light loss problem.
Therefore, it is desirable to provide a light-guiding module for backlight unit, which can avoid significant light loss and improve the luminous efficiency of the backlight unit.
The present invention has been accomplished in view of the above-noted circumstances. It is an objective of the present invention to provide a method of making a light-guiding module, which enables a light guide plate and a reflector to be made integrally so that the light-guiding module made therefrom can have a low light loss so as to improve the luminous efficiency of the backlight unit in which the light-guiding module is used.
To achieve this objective of the present invention, a method of making a light-guiding module includes the steps of: (a) applying a layer of light guide material containing methyl methacrylate oligomers on a reflector; and (b) polymerizing the methyl methacrylate oligomers of the light guide material at a temperature ranging from 55° C. to 70° C. to form a light guide plate containing polymethylmethacrylate and integrally combining the reflector.
In step (a), the light guide material may contain a plurality of diffusing particles having an average particle size ranging from 0.1 μm to 100 μm. Preferably, the average particle size of said diffusing particles ranges from 1 μm to 10 μm.
In step (a), the reflector may be prepared from polymethylmethacrylate.
In step (a), the reflector may contain a plurality of reflecting particles selected from the group consisting of titanium dioxide particles, mica particles and a mixture thereof.
Preferably, the step (b) may be performed for at least 2 hours.
In step (b), the temperature may preferably be in a range of 60° C. to 65° C.
Preferably, the method of the present invention may further comprise a step of (c) polymerizing the polymethylmethacrylate at a temperature ranging from 115° C. to 130° C. after step (b).
Preferably, the step (c) may be performed for at least one hour.
In step (a), the light guide material may be applied on the reflector by casting, injection molding or extrusion molding.
Referring to
In step (a), as shown in
In step (b), as shown in
A step (c) of further polymerizing the polymethylmethacrylate (PMMA) in the light guide plate 20 (or even in the reflector 10) at a temperature of about 115° C. to 130° C., preferably 120° C. to 125° C., for at least one hour, preferably 1-2 hours, can be carried out after the step (b) so as to enhance the structural strength of the light-guiding plate 20 and the bonding strength between the light guide plate 20 and the reflector 10.
Since there is no any gap between the light guide plate 20 and the reflector 10, the invention effectively eliminates the light loss problem of conventional designs. Therefore, the light-guiding module 22 of the present invention effectively improves the luminous efficiency of the backlight unit. Further, because the light guide plate 20 and the reflector 10 are integrally made as a unit, the invention greatly simplifies the manufacturing procedure, shortens the manufacturing time and lowers the manufacturing cost, thereby enhancing product marketability.
It is to be understood that the above-mentioned preferred embodiment is given by way of illustration only, and thus is not limitative of the present invention. For example, in step (a), the light guide material 18 is applied on the top surface of the reflector 10 by casting; however, injection molding or extrusion molding may be used. The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
