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Patent Searching and Data


Title:
PROJECTION OPTICAL SYSTEM AND PROJECTOR
Document Type and Number:
WIPO Patent Application WO/2018/096934
Kind Code:
A1
Abstract:
The purpose of the present invention is to provide a projection optical system made up of seven lens groups capable of securing a long back focus, and a projector incorporating the projection optical system. The seven lens groups constituting the projection system are made up of lens groups G1 through G7 the refractive powers of which are negative, positive, positive, negative, positive, positive, and positive in order from the magnification side. The long back focus can be secured with the entire negative refractive power shifted to the magnification side when the conditional expression shown below is satisfied: 5 <νdR − νdF < 30 Where νdR represents a dispersion value of the lens L71 which is furthest away on the reduction side in the seventh lens group G7 and νdF represents a dispersion value of the lens L11 which is furthest away on the magnification side in the first lens group G1.

Inventors:
SAKAI Toshihiko (3-5 Owa 3-chom, Suwa-shi Nagano 02, 〒3928502, JP)
SHIOKAWA Koji (3-5 Owa 3-chom, Suwa-shi Nagano 02, 〒3928502, JP)
Application Number:
JP2017/040394
Publication Date:
May 31, 2018
Filing Date:
November 09, 2017
Export Citation:
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Assignee:
SEIKO EPSON CORPORATION (1-6 Shinjuku 4-chome, Shinjuku-ku Tokyo, 01, 〒1608801, JP)
International Classes:
G02B13/16; G02B13/18; G02B15/20; G03B21/00; G03B21/14; H04N5/74
Domestic Patent References:
WO2013076931A12013-05-30
Foreign References:
JP2012048016A2012-03-08
JP2006234893A2006-09-07
JP2011028123A2011-02-10
JP2013200454A2013-10-03
JP2016133756A2016-07-25
Attorney, Agent or Firm:
WATANABE Kazuaki et al. (2070 Kotobuki Koaka Matsumoto-shi Nagano, 02, 〒3998702, JP)
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