1. Field of the Invention
The present invention relates to a light guiding device and a backlight module employing the light guiding device, the backlight module typically being part of an LCD (liquid crystal display).
2. Description of Prior Art
Because an LCD device has the merits of being thin, light in weight, and drivable by a low voltage, it is extensively employed in various electronic devices.
In an LCD device, usually a backlight module having a light source and a light guiding device is used to provide the needed illumination. The light source emits light beams to the light guiding device, which then transmits the light beams to illuminate liquid crystal molecules in a liquid crystal panel. It is important that the light guiding device transmits light beams to the liquid crystal panel uniformly.
Referring to
The light source cover 86 functions mainly as a reflection element, to ensure that most if not all of the light beams emitted from the light source 85 enter the light guide plate 81 through the light incident surface 811. The light beams are transmitted in the light guide plate 81 and reflected by the reflection member 82, and emit from the light emitting surface 813. The diffusing plate 83 diffuses the light beams so that they are more uniformly distributed. The converging plate 84 then converges the light beams to illuminate a liquid crystal panel (not shown).
Referring to
It is desired to provide a new light guiding device and a corresponding backlight module which overcome the above-described problems.
It is an object of the present invention to provide a light guiding device which yields uniform illumination at two opposite sides thereof, and a backlight module incorporating such a light guiding device.
A light guiding device of the present invention comprises a light guide plate comprising a light incidence surface and two opposite light emitting surface; and a reflection member comprising two opposite reflection surfaces. The light guide plate defines a space receiving the reflection member therein, and an opening for accessing the space, and the reflection surfaces of the reflection member face the light emitting surfaces of the light guide plate respectively.
A backlight module of the present invention comprises the above-described light guiding device, and a light source disposed adjacent to the light incidence surface of the light guide plate.
Other objects, advantages, and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
Referring to
In assembly, the reflection member 26 is received in the inner space such that the top reflection surface 28 and the bottom reflection surface 29 face the light emitting surfaces 23, 22, respectively.
Referring to
In summary, in most mobile phones that have two display screens, the external display is smaller than the internal display. The backlight module 2 used in such a mobile phone does not waste light, because the bottom diffusing area corresponding to the external display is the same size as the size of the display.
The light guiding device 2 employs the light guide plate 20 having the light emitting surfaces 22, 23, and the reflection member 26 having the reflection surfaces 28, 29. The light guiding device 2 can therefore provide uniform illumination at two opposite sides. The reflection member 26 is accommodated in the inner space of the light guide plate 20, which makes the whole light guiding device 2 comparatively thin and light.
The reflection member 26 can be made by any of the following methods: 1) integrally forming a transparent body, and then attaching two reflection films on two opposite sides of the body respectively; 2) combining two thin reflection plates together; or 3) polishing two opposite sides of a silver or aluminum plate.
The inner space 25 containing the reflection member 26 can be configured to position the reflection member 26 relative to the light emitting surfaces 22, 23. For example, the inner space 25 can be configured to be nearer to one of the light emitting surfaces 23, 22 of the light guide plate 20, so that a suitable distribution of light beams reaches the respective light emitting surfaces 22, 23. The top and bottom diffusing areas of the reflection member 26 can have both their locations and sizes configured according to the particular needs of various double screen electronic devices in which the light guiding device 2 is employed.
In other embodiments, where brighter illumination is required, the light source 200 can be one or more CCFLs (Cold Cathode Fluorescent Lamps) instead of an LED. The light guide plate 20 can be wedge-shaped instead of having a rectangular profile. The reflection member 26 can be wedge-shaped instead of having a rectangular profile.
It is to be further understood 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 |
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09129553 | Oct 2003 | TW | national |