Invention Grant
- Patent Title: Projection type image display apparatus
- Patent Title (中): 投影型图像显示装置
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Application No.: US13473025Application Date: 2012-05-16
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Publication No.: US08408717B2Publication Date: 2013-04-02
- Inventor: Koji Hirata , Takanori Hisada , Masahiko Yatsu
- Applicant: Koji Hirata , Takanori Hisada , Masahiko Yatsu
- Applicant Address: JP Tokyo
- Assignee: Hitachi, Ltd.
- Current Assignee: Hitachi, Ltd.
- Current Assignee Address: JP Tokyo
- Agency: Antonelli, Terry, Stout & Kraus, LLP.
- Priority: JP2006-166434 20060615
- Main IPC: G03B21/14
- IPC: G03B21/14 ; G03B21/28

Abstract:
A projection type image display apparatus includes a first lens group including a plural number of lenses being disposed in a direction of propagation light with respect to an image display element, a second lens group including a plural number of lenses being disposed in a direction of propagation light with respect to said first lens group and a reflection mirror, which is configured to reflect light emitted from at least one of said first and second lens groups, so as to project the light obliquely upon a screen. A ratio (Lo/Lp) of a diagonal size (Lo) of said screen and a distance (Lp) from a center of said reflection mirror to said screen is at least 2, and the second lens group includes a refractive lens having a negative power and a rotationally symmetric surface configuration.
Public/Granted literature
- US20120229777A1 Projection Type Image Display Apparatus Public/Granted day:2012-09-13
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