Light guide plate and surface light source device

A mobile device comprising:

• a liquid-crystal display device comprising:
• a light source that emits light;
• a light guide plate comprising:
• a light introducing portion that confines light that is incident from an end surface opposite the light source on which light from the light source is incident;
• and
• a light guide-plate main body configured to emit incident light to an outside from a light emitting surface and provided continuously with the light introducing portion in a thickness smaller than a maximum thickness of the light introducing portion,
• wherein the light introducing portion comprises an inclined surface inclined toward the light guide-plate main body from a surface comprising a larger thickness than a thickness of the light guide-plate main body, on at least one of a surface at a light emission side and a surface opposite to the surface at the light emission side,
• wherein the inclined surface comprises a main-inclined surface configured to be positioned in front of the light source arranged opposite to the end surface,
• wherein the inclined surface comprises:
• an average direction of normal lines oriented to a direction perpendicular to the end surface when viewed from a thickness direction, and
• side-inclined surfaces positioned at both sides of the main-inclined surface,
• wherein each of the side-inclined surfaces comprises average directions of normal lines inclined to the main inclined surface when viewed form the thickness direction,
• wherein directional transform patterns are formed on the main-inclined surface and on the side-inclined surfaces at both sides of the main-inclined surface,
• wherein the side-inclined surfaces are formed continuously with the main-inclined surface,
• wherein the directional transform patterns are a layout of pattern elements that linearly extend,
• wherein the pattern elements that form the directional transform patterns formed on the side-inclined surfaces comprise bilaterally asymmetrical cross-sectional shapes,
• wherein the directional transform patterns of the side-inclined surfaces are formed such that a ridge line and a valley line are alternately arranged and a slant surface is formed between the ridge line and the valley line, and
• wherein, of adjacent ones of the slant surfaces, a slant surface on which an outward normal line is further oriented to a center of the light guide plate than a direction perpendicular to the pattern-element layout direction comprises a smaller width parallel to a pattern-element layout direction than that of a slant surface on which an outward normal line is further oriented to an outer side of the light guide plate than a direction perpendicular to the pattern-element layout direction;
• and
• a liquid-crystal display panel arranged opposite to the light emitting surface of the light guide plate.