A dot pattern of a light guide plate is optimally designed for a surface light source device of side light type. A lamp 1 is disposed at the side of the light guide plate 2 and light introduced from a light incidence surface into the light guide plate 2 is emitted from a luminous surface. The dot pattern is arranged on the rear surface of the light guide plate 2 according to the following principles: (1) there is a (gradient) portion where the rate of area occupation of the dot pattern increases from a region (usually a far region) lowly exposable to light from the lamp 1; and (2) there is no sharp variation in the rate of area occupation of the dot pattern. At a corner of the light guide plate 2, a substantially triangular dot pattern is disposed for compensating any luminance drop due to the location in the vicinity of an electrode portion 1a of the lamp 1.
An exemplary light guide plate includes a light input surface, a bottom surface, a light output surface opposite to the bottom surface, and a plurality of dots. The dots are arranged on the bottom surface in series of adjacent columns parallel to the light input surface. A distance between two dot centers of two adjacent dots and sizes of the dots in a same dot column are uniform. Each dot column defines a column axis that passes through dot centers of each of the dots. A distance between two adjacent column axes increases with increasing distance from the first light input surface. A backlight module using the light guide plate is provided.
An exemplary light guide plate includes a light input surface, a bottom surface, a light output surface opposite to the bottom surface, and a plurality of dots. The dots are arranged on the bottom surface in series of adjacent columns parallel to the light input surface. Each dot column defines a column axis that passes through centers of the dots. A distance between two adjacent column axes increases with increasing distance from the first light input surface. A distance between centers of two adjacent dots in the same column increase with increasing distance from a center of the column to each of two opposite ends of the column. A backlight module using the light guide plate is also provided.
A plane light source has a light source (50), a reflection cover (51) and a light guide plate (10). The light guide plate has a wedge-shaped base plate (20), an array of reflection lumps (30), and an array of round protrusions (40). The base plate has a light incidence surface (21), a light emitting surface (23), and a bottom surface (25) opposite to the light emitting surface. The reflection lumps are disposed on the bottom surface, and penetrate into the base plate. The round protrusions are disposed on the light emitting surface for diffusing light. Each reflection lump corresponds to a respective one of the round protrusions. Each reflection lump has a reflecting surface (301) for reflecting incident light to the corresponding round protrusion of the light emitting surface.
A light guide plate includes at least one surface including a first region having relatively small surface roughness and a second region having relatively great surface roughness, which are adjacently formed. A boundary-blurring pattern composed of a plurality of surface roughness aspects is formed in a boundary part between the first region and the second region.
A non-scattering light pipe includes a transition surface between a first side wall and an input surface and a second side wall and the input surface. The transition surface is arranged to substantially obscure the corner interfaces between the first and second side walls and the input surface such that in the corner formation any imperfections therein are not imaged into the output. Most preferably, the transition surface is optimized to provide a substantially uniform light intensity distribution. A light pipe in accordance with the preferred embodiments of the present invention is further arranged to couple to a linear light source, such as a cold cathode fluorescent light (CCFL). The light source is arranged such that dim areas, i.e., areas of the light source having non-uniform intensity, are not disposed adjacent the input surface.
