Light guide plate, surface light source device and liquid crystal display

A surface light source device comprising:

• a primary light source and a light guide plate supplied with light from said primary light source,
• said light guide plate having an emission face provided by a major face, a back face provided by another major face opposite with said emission face and an incidence face for introducing light supplied by said primary light source into said light guide plate,
• wherein
• said back face is provided with a great number of protrusion-shaped micro-reflectors for light-proceeding-direction conversion;
• each of said micro-reflectors includes a conversion output portion;
• said conversion output portion includes a ridge portion, a first inner-reflection face and a second inner-reflection face, said first and second inner-reflection faces extending on both sides of said ridge portion and being inclined with respect to a first representative plane representing said back face, respectively;
• said ridge, said first inner-reflection face and said second inner-reflection face provide a valley inside the micro-reflector;
• said valley are configured as to get narrower and shallower according to an increasing distance from said incidence face, thereby causing an inner input light reaching the valley to be reflected one of said first and second inner reflection faces and then the other of said first and second inner reflection faces and producing an inner output light proceeding toward said emission face;
• and,
• provided that x-axis, y-axis and z-axis are defined on each of said micro-reflectors so that (1) x-axis extends along a projection of a main approaching direction of the inner input light onto a second representative plane representing said emission face, (2) z-axis extends from said back face to said emission face as to be perpendicular to said emission face and (3) y-axis extends perpendicularly to both x-axis and z-axis as to form a right-hand coordinate system in combination with x-axis and z-axis,
• and further provided that a standard posture of a micro-reflector is defined as a posture such that (i) a projection of an extending direction of the ridge of the conversion output portion onto xy-plane accords with x-axis direction, (ii) a bisectional plane, which bisects an angle made by said first and second inner-reflection faces so that the ridge extends on said bisectional plane, is perpendicular to xy-plane and (iii) an inner input light inner-inputted to the micro-reflector from a main approaching direction is converted into an inner output light proceeding in z-axis direction,
• each of said micro-reflectors has a posture which is substantially deviated from said standard posture around x-axis, y-axis and z-axis.

A liquid crystal display comprising:

• a liquid crystal display panel and a surface light source device for illuminating the liquid crystal display panel,
• said surface light source device comprising a primary light source and a light guide plate supplied with light from said primary light source,
• said light guide plate having an emission face provided by a major face, a back face provided by another major face opposite with said emission face and an incidence face for introducing light supplied by said primary light source into said light guide plate,
• wherein
• said back face is provided with a great number of protrusion-shaped micro-reflectors for light-proceeding-direction conversion;
• each of said micro-reflectors includes a conversion output portion;
• said conversion output portion includes a ridge portion, a first inner-reflection face and a second inner-reflection face, said first and second inner-reflection faces extending on both sides of said ridge portion and being inclined with respect to a first representative plane representing said back face, respectively;
• said ridge, said first inner-reflection face and said second inner-reflection face provide a valley inside the micro-reflector;
• said valley are configured as to get narrower and shallower according to an increasing distance from said incidence face, thereby causing an inner input light reaching the valley to be reflected one of said first and second inner reflection faces and then the other of said first and second inner reflection faces and producing an inner output light proceeding toward said emission face;
• and,
• provided that x-axis, y-axis and z-axis are defined on each of said micro-reflectors so that (1) x-axis extends along a projection of a main approaching direction of the inner input light onto a second representative plane representing said emission face, (2) z-axis extends from said back face to said emission face as to be perpendicular to said emission face and (3) y-axis extends perpendicularly to both x-axis and z-axis as to form a right-hand coordinate system in combination with x-axis and z-axis,
• and further provided that a standard posture of a micro-reflector is defined as a posture such that (i) a projection of an extending direction of the ridge of the conversion output portion onto xy-plane accords with x-axis direction, (ii) a bisectional plane, which bisects an angle made by said first and second inner-reflection faces so that the ridge extends on said bisectional plane, is perpendicular to xy-plane and (iii) an inner input light inner-inputted to the micro-reflector from a main approaching direction is converted into an inner output light proceeding in z-axis direction,
• each of said micro-reflectors has a posture which is substantially deviated from said standard posture around x-axis, y-axis and z-axis.