Light guide plate with compensated emission light field

(a) Technical Field of the Invention

The present invention relates to a light guide plate, and in particular to a light guide plate that compensates and correct a light field generated therein to enhance uniformity of light emission thereof.

(b) Description of the Prior Art

As shown in FIG. 1 of the attached drawings, conventionally, a light guide plate 1 comprises a light incidence surface 11, a light reflection surface 12, and a light emission surface 13. The light incidence surface 11 receives the incidence of light from a mated light source A, which is often a linear light source coextensive with the light incidence surface 11 of the light guide plate 1. The light gets into the light guide plate 1 through the light incidence surface 11 and transmits deeply into the light guide plate 1. A portion of the light that transmits into the light guide plate 1 reaches the light reflection surface 12 at which the portion of the light is reflected toward the light emission surface 13. To enhance convergence of the light, both the light emission surface 13 and the light reflection surface 12 are provided with parallel and elongated light-guide structures 131, 121, which are composed of raised ribs having V-shaped cross-sections. The light-guide structures 131 of the light emission surface 13 are extended in a direction substantially normal to the linear light source A, while the light-guiding structures 121 of the light reflection surface 12 are substantially parallel to the light source A. With this arrangement, when transmitting through or reflected by or otherwise interacting with side faces of the rib-like light-guiding structures 131, 121 to leave the light guide plate 1, can realize multi-directional light convergence.

Such a conventional structure of light guide plate, although effective in realizing multidirectional light convergence, still suffers drawbacks. This is due to the fact that when the light source A gives off light, divergence angles of the light occur at opposite ends of the light source A, as shown in FIGS. 2 and 3, so that when the light enters the light guide plate 1, the distribution of light field close to the opposite ends of the light guide plate 1, which correspond to the ends of the light source A, shifts toward the ends. This prevents the V-shaped light-guiding structures 121 of the light reflection surface 12 from providing the optimum performance over the shifted light field and consequently, the coordination between the light reflection surface 12 with the light emission surface 13 to ensure excellent light emission cannot be achieved, which leads to poor overall light emission of the light guide plate 1.

In view of the above discussed drawback, it is desired to provide a light guide plate that compensates the drawback caused by the light divergence angle of the light source.

The primary purpose of the present invention is to provide a light guide plate that overcomes the problem that divergence angles are induced at lengthwise ends of a light source that provides light to the light guide plate and cause end portions of light field within the light guide plate to shift endwise, leading to poor performance of the light emitted from the light guide plate.

To realize the above objective of the present invention, a light guide plate is provided, comprising a light incidence surface, a light reflection surface, and a light emission surface. The light emission surface forms a plurality of light-guiding structures, which are extended in a direction substantially perpendicular to a lengthwise direction of a light source that is arranged to provide light to the light guide plate. The light-guiding structures have a substantially V-shaped cross-section and, among the light-guiding structures, those arranged in opposite endwise zones of the light emission surface in the lengthwise direction have an irregular V-shaped cross-section defined by a long inclined side and a short inclined side. The long and short sides respectively form first and second inclined angles with respect to the light emission surface and the first included angle is smaller than the second included angle and the first inclined angle gets smaller with the associated light-guiding structure located closer to the lengthwise end.

The foregoing object and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts.

Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.