Spread illuminating apparatus
AssigneeMinebea Co., Ltd.
InventorShingo Suzuki
Life of this patent
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Abstract
In a light reflection pattern formed on a bottom surface of a light conductive plate, an inclined surface of grooves positioned at a predetermined distance or farther from a lamp includes a non-flat portion whose inclination angle varies gradually. Light rays traveling in the light conductive plate are reflected at the non-flat portion with an appropriate angle suitable for increasing a viewing field angle and exit out from a top surface of the light conductive plate. Consequently, the viewing field angle at the portion positioned at a predetermined distance or farther from the lamp can be increased.
Claims9
A spread illuminating apparatus of side light type, comprising:
- a light conductive plate made of a light-transmissible material;
- a bar-like lamp disposed close to and along at least one end surface of the light conductive plate;
- and
- a light reflection pattern including a large number of grooves each having an inclined surface in section and formed on one major surface of the light conductive plate,
- wherein the grooves are formed in such a manner that a depth of each of the grooves increases gradually with an increase in a distance from the lamp,
- the grooves having the depth equal to a predetermined depth or larger than the predetermined depth have an inclined surface including a non-flat portion having an inclination angle that varies gradually, and
- an area of the non-flat portion increases gradually with the increase in the distance from the lamp.
Dependencies are inferred from the claim text.