Abstract: A set of light guide blocks B L 1˜B L 3 provide a tandem arrangement. The light guide block B L 1 is supplied with light from a primary light source L 1. The other primary light sources L 2, L 3 are arranged in recesses formed around distal portions of the light guide blocks B L 1, B L 2, supplying the light guide blocks B L 2, B L 3 with primary light, respectively. Overlap of mutually neighboring light guide blocks gives tang-shaped overlapping portions 17a, 17b, 27a, 27b as well as overlapping bands 17c, 27c, thereby avoiding electrodes at both ends of the primary light sources L 2, L 3 from causing short of brightness. The light guide blocks B L 1˜B L 3 may be in the form of unified single guide plate. Primary light sources L 1˜L 3 may have a shape such that electrode sections of both ends are curved. A compact surface light source device with a large emission area is provided.

Abstract: An asymmetric prism sheet, surface light source and LCD to which the asymmetric prism sheet is applied is provided. A cold cathode tube backed by a reflector supplies light to an incidence surface of a directional emission guide plate. A polarization separation sheet and a liquid crystal panel are disposed outside of the asymmetric prism sheet, with the reflector disposed along a back face. First and second slopes of each asymmetric prism element rows have inclination angles &phgr;a, &phgr;b which are selected as to allow a secondary ray to exist inside a main ray emitted from a frontal face in a manner such that the main ray is deflected toward a generally frontal direction by way of internal reflection of the second slope while the secondary ray is deflected toward a generally frontal direction by way of double internal reflection of the first and second slopes. An outer face provides an uneven face such as non-glare-processed face, orthogonal prismatic face or lens face.

Abstract: A light source device outputs illumination light with highly uniform tint. The light source device is comprises a scattering guide provided with scattering power inside, a light supplier to supply light to an end face portion of the scattering guide. Light is introduced into the scattering guide plate to be followed by emission from an emission face of the scattering guide. Scattering efficiency is intentionally balanced in a long wavelength region and in a short wavelength region so that regions near the end face and far from the end face are approximately equal in color temperature of output light. Relation between Q(R), efficiency in a long wavelength region, and Q(B), scattering efficiency in a short wavelength region, are designed so that k=Q(B)/Q(R) falls within a range 0.75≦k≦1.25.

Abstract: A light scattering and guiding light source device which is capable of providing a uniform illumination light, simple structure and low cost. A wedge-shaped light scattering guide has an incident surface for introducing light rays from a fluorescent lamp. The directions of the rays are changed by scattering. The rays propagate through the body while reflected repeatedly. Parts of the rays go outwards at plural reflective points. The angle of reflection increases successively, thus increasing the possibility that the light exits from the exit surface. This effect cancels another effect that portions close to the light source shines strongly. Both effects are balanced to make uniform the brightness over the exit surface. Reflective sheets are disposed along the inclined surface and around the fluorescent lamp to keep the brightness high. A prismatic exit direction modifier giving on the light exit surface is employed to modify the light exit direction characteristic.

Abstract: Provided are a surface light source device whose bright surface is excellent in whiteness and softness and a liquid crystal display that ensures a high visual quality. A relatively thick side end surface of a light scattering guide 1, which has a wedge-shaped profile, forms an incidence surface 2. A fluorescent lamp L is located in the vicinity of the incidence surface 2, and a silver foil R is arranged around it. A prism sheet 4 is located outside an exit surface 5. The orientation of the prism sheet 4 is selected so that the running direction of prismatic rows is in line with the transverse direction of the light scattering guide 1. The prismatic surface may be directed inward or outward. A prism sheet 8 is interposed between a back surface 6 of the light scattering guide 1 and a reflector (silver foil) 3. The prism sheet 8 is arranged so that its prismatic surface is directed inward.

Abstract: A fluorescent lamp L is arranged in the vicinity of an incidence surface 2 of a light scattering guide plate 1. A prism sheet 4' having rows of prism elements and rows of lens elements on each side is arranged outside an exiting surface 5. The angles of inclination of slopes 4a and 4b satisfy a condition that .phi.a>.phi.b. The slopes 4a and 4b extend in the transverse direction of the light scattering guide plate 1, and slopes 4c and 4d extend in the longitudinal direction. A reflector 3 is arranged along a rear surface 6. Light emitted from the exiting surface 5 is efficiently propagated by an inner prism surface toward a forward direction, shifted in the transverse direction by an outer prism surface or the lens element surfaces 4c and 4d, and is then returned inwardly. The path histories of light emitted from the prism sheet 4' is diversified to improve visual characteristics.

Abstract: There is provided a surface light source device which is excellent in whiteness and softness of a luminant surface and able to retain reflective appearance from occurring. The surface light source device is effectively applied to back lighting in a liquid crystal display. A fluorescent lamp (L) is disposed in the vicinity of an incidence surface (2) of a light guide plate (1). A prism sheet (4') having prism surfaces formed on both surfaces is disposed along an exiting surface (5). The prism sheet (4') is oriented such that prism rows (4a, 4b) on the inside surface run in the transverse direction of the light guide plate (1) while prism rows (4c, 4d) on the outside surface run in the longitudinal direction of the light guide plate (1). A reflector (3) is disposed along a back surface (6) of the light guide plate (1).