Title:
ZOOM LENS FOR PROJECTION
Document Type and Number:
Japanese Patent JP2015018203
Kind Code:
A
Abstract:
PROBLEM TO BE SOLVED: To achieve a zoom lens for projection having an extremely wide field angle: the one having a half field angle ωw of 34 degrees to 45 degrees at the wide angle end.SOLUTION: There is provided a zoom lens for projection used in an image display device that projects images on a projection target surface to be displayed in an enlarged form, and having a five-lens group configuration comprising first lens group G1 to fifth lens group G5 arranged from the enlargement side to the reduction side, where the first lens group G1 has a negative refractive power, the second lens group G2 has a negative refractive power, and the third lens group G3 has a positive refractive power. When the magnification is varied from the wide angle end to the telephoto end, the fifth lens group G5 is moved to the enlargement side, and a half field angle ωw at the wide angle end satisfies the condition (1): 34 degrees≤ωw<45 degrees.
Inventors:
KUBOTA TAKASHI
Application Number:
JP2013209631A
Publication Date:
January 29, 2015
Filing Date:
October 04, 2013
Export Citation:
Assignee:
RICOH CO LTD
International Classes:
G02B15/20; G02B13/16; G02B13/18; G03B21/00; G03B21/14
Domestic Patent References:
| JP2007286233A | 2007-11-01 | |||
| JP2010211056A | 2010-09-24 | |||
| JPH11167063A | 1999-06-22 | |||
| JP2006058584A | 2006-03-02 | |||
| JP2011002817A | 2011-01-06 | |||
| JP2011227124A | 2011-11-10 | |||
| JP2002311330A | 2002-10-23 | |||
| JP2006098962A | 2006-04-13 |
Attorney, Agent or Firm:
Shuichi Kudo
Toru Kabayama
Shogo Honda
Toru Kabayama
Shogo Honda
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