Title:
PROJECTION DEVICE AND PROJECTION SYSTEM
Document Type and Number:
Japanese Patent JP2016142883
Kind Code:
A
Abstract:
PROBLEM TO BE SOLVED: To provide a projection device in which a projection distance is very short and higher luminance can be attained, and which is compact, has high performance, and has excellent temperature characteristics.SOLUTION: In a dioptric system 11, in order from an image forming unit LV, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, and a fourth lens group G4 having positive refractive power, are arranged. In the first lens group G1, a cemented lens that is constituted of a positive lens P1 and a negative lens N1 and satisfies a prescribed conditional expression is arranged more on an enlargement side from a diaphragm S. Accordingly, a variation of a focal length and an expansion due to a heat of a mechanical holding unit are balanced. Further, since the positive lens L1 closest to the image forming unit LV is formed of an aspherical lens, a temperature change in curvature of field can be adjusted at a higher level.SELECTED DRAWING: Figure 3
Inventors:
TAKANO YOHEI
Application Number:
JP2015018000A
Publication Date:
August 08, 2016
Filing Date:
January 30, 2015
Export Citation:
Assignee:
RICOH CO LTD
International Classes:
G02B17/08; G02B13/18; G03B21/10; G03B21/14
Domestic Patent References:
| JP2014235414A | 2014-12-15 | |||
| JP2014106307A | 2014-06-09 | |||
| JP2014102529A | 2014-06-05 |
Attorney, Agent or Firm:
Shuji Sanada
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