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AssigneeNippon Sheet Glass Co., Ltd.
InventorsKozo Fujino, Vladimir Victrovich Serikov, Shinji Kawamoto, Masafumi Taguchi
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A light guide 1 is provided at the reverse side thereof with triangular uneven surfaces 1b at a predetermined pitch. The uneven surfaces 1b are integrally formed with the light guide 1 when the latter 1 is injection-molded. Incident light from a light incident plane is caused to be scattered at uneven surfaces 1b within the light guide and to spread in a main scanning direction. The light scattered is emitted from an emission plane. Intensity of light in the main scattering direction can be made uniform by lengthening the uneven surfaces 1b as the uneven surfaces extend from the light incident plane. A position where the light intensity becomes maximum in a sub-scanning direction can be changed by adjusting an angle between the ridgeline of the uneven surfaces 1b and the sub-scanning direction, and distributed characteristics of the light intensity in the sub-scanning direction can be also changed.
A light guide for transmitting, along a longitudinal direction, incident irradiation light from one end of the light guide, and for emitting this irradiation light from an emission plane, said light guide being provided at one end thereof with luminous means, characterized in that the light guide is provided with a light incident plane, an emission plane, and a reverse side spaced from the emission plane, said light guide having said light incident plane, said emission plane, and said reverse side being a unitary member, said reverse side having uneven surfaces for scattering the incident irradiation light so that a portion of the scattered light is emitted from the emission plane, wherein the uneven surfaces also comprise a plurality of ridgelines extending in a direction that is not perpendicular to the longitudinal direction, so that a portion of the light is reflected by the uneven surfaces toward the emission plane and emitted therefrom, and wherein the uneven surfaces are formed so that the uneven surfaces have a length that varies with distance from the end provided with the luminous means.
Dependencies are inferred from the claim text.