Title:
投射用レンズ
Document Type and Number:
Japanese Patent JP4532630
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To actualize a lens for projection which has an F number of about 2.4, maintains high resolving power although it has a large half field angle of >=45 deg., and has long back focus enough for color composite means disposition and high telecentricity. SOLUTION: A 1st lens group I with negative refracting power, a 2nd lens group II with positive refracting power, and a 3rd lens group III with positive refracting power are arranged from the enlargement side to the reduction size; and the 1st lens group I and 2nd lens group II has a relatively long interval, the 1st lens group I is all composed of negative lenses, and the most reduction side lens in the 1st lens group I has an aspherical surface.
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Inventors:
Kuniyuki Tobinai
Application Number:
JP29839999A
Publication Date:
August 25, 2010
Filing Date:
October 20, 1999
Export Citation:
Assignee:
Ricoh Optical Co., Ltd.
International Classes:
G02B13/18; G02B13/24
Domestic Patent References:
| JP2000305012A | ||||
| JP8201688A | ||||
| JP996759A |
Attorney, Agent or Firm:
Toru Kabayama
Shogo Honda
Shogo Honda