Spread illuminating apparatus with a uniform illumination
AssigneeMinebea Co., Ltd.
InventorKiyoshi Kusakabe
Life of this patent
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Abstract
The light dispersion portion is formed with the grooves having an identical depth D, and the spacing P between the light dispersions 15 is set 0.01 mm minimum and 0.2 mm maximum. In order to prevent the stripe pattern of brightness and darkness generated due to the light reflection at the light dispersion portion 15, it is preferable to make the spacing as small as possible. However, too small spacing makes it difficult to ensure workability. Accordingly, the minimum value of spacing is set 0.01 mm in view of workability. And, the maximum value of spacing is set 0.2 mm, which does not allow visual recognition of the stripe of brightness and darkness.
Claims4
A spread illuminating apparatus in which a bar-like light source is disposed close to an end surface of a transparent substrate made of a light permeable material, wherein the bar-like light source is formed with a bar-like light conductive member made of a transparent material, disposed close to and along at least one end surface of the transparent substrate and having a length per spot-like light source set within 30 mm and a spot-like light source disposed to at least one end of the light conductive member, and an optical path conversion means comprising light dispersion portions formed with grooves having an identical depth and spaced from each other at a range from 0.01 mm to 0.2 mm is provided at least on a surface of the light conductive member opposite to the surface facing the transparent substrate.
Dependencies are inferred from the claim text.