The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 03, 2010
Filed:
May. 07, 2004
Tetsuya Hoshino, Tsukuba, JP;
Yasushi Sugimoto, Tsukuba, JP;
Tetsuya Hoshino, Tsukuba, JP;
Yasushi Sugimoto, Tsukuba, JP;
Hitachi Chemical Company, Ltd., Tokyo, JP;
Abstract
A hologram optical element having a thin form and a high degree of light transmittance, moreover that provides superior handling ease, as well as a surface light source device employing this hologram optical element. The angle at which light can be bent in this hologram optical element, has low wavelength dependency, and the hologram optical element enables prevention of spectral separation in white light incident from an oblique direction which is bent to a vertical direction and emitted. A transmitting diffraction grating, when light of wavelengths λ1, λ2 and λ3 within the ranges 0.46≦λ1≦0.50 μm (blue light), 0.53≦λ2≦0.57 μm (green light), 0.60≦λ3≦0.64 μm (red light) is incident at angle θi, the maximum diffraction angle for diffractive efficiency of each wavelength is within the range from −5 degrees to +5 degrees.