Optical components and surface light source devices

Abstract

Provided are an optical element and a planar light source device capable of achieving, in a directly-below light source scheme, a uniform planar light emission while the distance in the emission direction is kept small. The optical element (30) comprises over a flat plate surface at least one prism group formed by a plurality of prism top portions (32), each extending in the shape of a spiral from a central axis (31) to the outer periphery.

Description

technical field [0001] The present invention relates to an optical element and a surface light source device provided with a prism group on the front. Background technique [0002] For example, an illuminated pushbutton switch is provided in an elevator so as to enable input of a destination floor. In recent years, it is desired that the illuminated pushbutton switch emits light evenly. [0003] As a structure for uniformly lighting the conventional illuminated push button switch, such as Figure 10 As shown in (a), (b), and (c), three control methods are generally known. Among them, in Figure 10 As shown in (a), the method of disposing the convex lens 102 directly above the light source 101 to control the directivity, or Figure 10 In the so-called direct light source method such as the light guide control method in which the light from the light source 111 is emitted through the light guide pipe 112 shown in (b), there is a problem that the distance in the emission direct...

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Problems solved by technology

[0005] However, with regard to the luminance distribution of the surface light source device of the direct light source system, if there is no optical element such as a microlens array, as in Figure 11 As shown by the dotted line in (a), the top of the light source is too bright, and the surrounding area is too dark

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