Abstract: A light guide plate is formed of a light introducing part positioned to face a point light source for confining light and a light guide plate body having a thickness smaller than the thickness of an end of the light introducing part on a point light source side and causing the confined light to be output from a light exit surface to outside. The light introducing part has an inclined surface, and a directivity conversion pattern formed on the inclined surface. The directivity conversion pattern is configured by arranging V grooves in parallel to each other, each having a vertical angle of 120°, and each extends in a direction approximately perpendicular to a light incidence end face of the light guide plate. The length of the inclined surface in a inclination direction where part of light incident to the light introducing part enters the inclined surface at least twice.

Abstract: A surface light source device includes a point source of light and a light guide plate causing light from the point source of light introduced from a light incident end face and emitted from a light emission surface to outside. The light guide plate is formed of a light introducing portion provided at an end of a light guide plate body. The point source of light is placed facing the light incident end face positioned at an end face of the light introducing portion. Along a region of the light introducing portion adjacent to the light guide plate body, a directivity converting portion is provided. The directivity converting portion is configured by arranging V-grooved directivity conversion patterns in an arc shape. A region of the light introducing portion has a thickness equal to that of the light guide plate body and has a surface positioned in the same plane.

Abstract: An area light source device that is capable of evenly emitting light by reducing leakage in the vicinity of the light source, and enhancing the light emission luminance by exiting light of narrower directional characteristics. A light guide substrate includes a light introducing section and a light guide plate main body. Diffusion patterns are provided at the light exit surface of the light guide plate main body. A low refraction index layer is formed at the lower surface of the light guide plate main body, and a reflection layer is formed at the lower surface of the low refraction index layer. The point light source is positioned facing an end face of the light introducing section. A directivity conversion unit is arranged on the upper surface of the light introducing section. The directivity conversion unit is configured by radially arraying a directivity conversion pattern having a V groove shape.

Abstract: An area light source device that is capable of more evenly emitting light and capable of enhancing the light emission luminance by exiting light of narrower directional characteristics. A light guide substrate includes a light introducing section and a light guide plate main body for exiting the light from a light exit surface. A number of diffusion patterns are formed at the light exit surface. A low refraction index layer is formed at the lower surface of the light guide plate main body, and a reflection layer is formed at the lower surface of the low refraction index layer. The point light source is arranged at a position facing the end face of the light introducing section. A tapered portion inclined to gradually increase the thickness of the light introducing section the farther away from the light source is arranged on the upper surface of the light introducing section.

Abstract: A surface light source device has a surface-shaped light source having a light emission surface, a first prism sheet at a side of the light emission surface, and a second prism sheet in an opposite side from the surface-shaped light source with the first prism sheet interposed therebetween. The first prism sheet includes prisms having a greater length in a longitudinal direction and having an apical angle between 72 and 100 degrees which are arranged on a surface facing the surface-shaped light source. The second prism sheet includes prisms having a greater length in a longitudinal direction and having an apical angle between 100 and 125 degrees which are arranged on a surface facing a direction opposite the surface-shaped light source. The first and second prism longitudinal direction form an angle of 15 degrees or less, when the first and second prism sheet are viewed in a perpendicular direction.

Abstract: A light guide plate (63) includes a light introducing section (65), which is at a position facing a point light source (62), for confining light from the point light source, and a light guide plate main body (64), which has a thickness smaller than a thickness at an end of the light introducing section on the point light source side, for outputting the confined light to an outside from a light outputting surface by light outputting means (70). The light introducing section (65) has an inclined surface (67), which is inclined from a surface of the light introducing section towards a surface of the light guide plate main body (64). The inclined surface (67) has a directivity converting pattern (68) for converting a directivity expansion in a thickness direction of the light guide plate of the light entered to the light introducing section (65) to directivity characteristics tilted towards a direction parallel to a surface direction of the light guide plate.

Abstract: On a light guide plate (32), a prism sheet (36), an uneven diffuser plate (37) and a correcting optical sheet (38) are placed one over another. Light outputted from the light guide plate (32) in a direction substantially parallel to a light outputting surface (45) is bent to a direction substantially vertical to the light outputting surface (45) by the prism sheet (36). Light which passed through the prism sheet (36) and has a long directivity characteristic in an r axis direction is converted into light having a substantially circular directivity characteristic by passing through the uneven diffuser plate (37). Furthermore, the light which passed through the uneven diffuser plate (37) and has the substantially circular directivity characteristic is converted into light having a directivity characteristic closer to a perfect circle by the correcting optical sheet (38). The correcting optical sheet (38) is formed of a pattern having many polyhedron shapes.

Abstract: A semi-permeable/reflective sheet (19) has a lower surface as a flag light incident surface (47) and a surface opposite to the light incident surface (47) where a light reflection area (43a) and a light transmittance area (43b) are provided. The light transmittance area (43b) is a flat surface parallel to the light incident surface (47). The light reflection area (43a) is formed by a convex pattern (42) having a cross section of a rectangular equilateral triangular shape. A part of light (41) coming from the light incident surface (47) to the light transmittance area (43b) transmits the semi-permeable/reflective sheet (19) and goes out of the surface opposite to the light incident surface (47). A part of the remaining light (41) incident from the light incident surface (47) is reflected twice by reflection walls (44, 45) forming the convex pattern (42).

Abstract: To make an efficiency of utilizing light with high efficiency in a plane light source apparatus used along with a liquid crystal display panel of a reflection type as a backlight, light f3 leaked from a rear face of a light guide plate 25 in a skewed direction, is incident on inside of a prism sheet 27 and reflected by a reflecting face 32. Light f3 reflected by the reflecting face 32, is reflected in a direction orthogonal to the prism sheet 27, passes the light guide plate 25 and is emitted from a light emitting face 30 of the light guide plate 25 in a direction orthogonally thereto.

Abstract: To make an efficiency of utilizing light with high efficiency in a plane light source apparatus used along with a liquid crystal display panel of a reflection type as a backlight, light f3 leaked from a rear face of a light guide plate 25 in a skewed direction, is incident on inside of a prism sheet 27 and reflected by a reflecting face 32. Light f3 reflected by the reflecting face 32, is reflected in a direction orthogonal to the prism sheet 27, passes the light guide plate 25 and is emitted from a light emitting face 30 of the light guide plate 25 in a direction orthogonally thereto.

Abstract: A method of producing shikonin, having the following chemical structure ##STR1## which method comprises dehydrating 2-(1'-acetoxy-4'-hydroxy-4'-methylpentyl)-5,8-diacetoxy-1,4-naphthoquinone , treating the resulting product with an alkali hydroxide and acidifying the treated product.