Surface light source device, liquid crystal display device, and mobile device

摘要

An area light source device has a light guide plate having an end face and a light exit surface, a light source that is disposed in a position facing the end face of the light guide plate, a plurality of optical sheets that are disposed on the light guide plate, a light shielding plate that is disposed so as to cover an upper portion of the light source, and a light blocking member that is provided between the end face of the light guide plate and the light exit surface. The end face of the light guide plate is configured to have light introduced therethrough. The light exit surface of the light guide plate is configured to output the light from the light guide plate. The light blocking member is different from the light shielding plate.

主权项

1. An area light source device comprising:
a light guide plate comprising an end face and a light exit surface; a light source that is disposed in a position facing the end face of the light guide plate; a plurality of optical sheets that are disposed on the light guide plate; a light shielding plate that is disposed so as to cover an upper portion of the light source; and a light blocking member that is provided between the end face of the light guide plate and the light exit surface, wherein the end face of the light guide plate is configured to have light introduced therethrough, wherein the light exit surface of the light guide plate is configured to output the light from the light guide plate, wherein the light blocking member is different from the light shielding plate, wherein, in the light guide plate, a light introduction part that introduces the light from the light source through an end face and a light guide plate body, which is thinner than a maximum thickness of the light introduction part and includes the light exit surface, are continuously formed,
wherein a proportion of a thickness of the light guide plate body to the maximum thickness of the light introduction part is less than or equal to 0.75, andwherein the plurality of optical sheets are stacked between the light shielding plate and the light blocking member, andwherein the following condition is satisfied:D⁢⁢e≧∑i=1n⁢t⁢⁢i×tan⁡[arcsin⁡(1/N⁢⁢i)], wherein n is the number of optical sheets, De is a distance between an end on a side farther away from the light source of the light blocking member and a light-exit-surface-side end edge of a portion covering the light source in the light shielding plate in a direction parallel to the light exit surface, ti is a thickness of the optical sheet located at an ith position from a bottom, and Ni is a refractive index of the optical sheet.