Title:
LENS FOR READING
Document Type and Number:
Japanese Patent JP2592033
Kind Code:
B2
Abstract:
PURPOSE: To provide a lens for reading a reduced image capable of sufficiently compensating aberrations with two component lenses and with less temp. dependency of reading performance by providing an image forming lens whose one surface is at least an aspherical surface and an auxiliary lens whose both surfaces are aspherical surfaces and satisfying specific conditions.
CONSTITUTION: This lens is composed of an image forming positive meniscus lens 1 whose convex surface confronts the object side and an auxiliary positive meniscus lens 2 whose convex surface confronts the object side. At least one surface of the image forming lens 1 is an aspherical surface. Both surfaces of the auxiliary lens 2 are aspherical surfaces. This lens satisfies conditions: 0.7<f<f1, 1.7<f2/f1, ν1>56 and 0.8<r1/r2<1.2 where (f) is the focal length of a whole system, f1 is the focal length of the image forming lens 1 and f2 is the focal length of the auxiliary lens 2. ν1 is an Abbe number of the material of the image forming lens 1. r1 is the on-axis radius of curvature of the front surface of the image forming lens 1 and r2 is the on-axis radius of curvature of the rear surface of the image forming lens 1.
Inventors:
KIKUTANI KAZUO
Application Number:
JP3254893A
Publication Date:
March 19, 1997
Filing Date:
January 29, 1993
Export Citation:
Assignee:
MAAKU KK
International Classes:
G02B13/18; G02B13/24; (IPC1-7): G02B13/24; G02B13/18
Domestic Patent References:
| JP4119308A |
Attorney, Agent or Firm:
Toshi Inoguchi
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