ORIGINAL READING LENS

Title:

ORIGINAL READING LENS

Document Type and Number:

Japanese Patent JPH04216519

Kind Code:

A

Abstract:

PURPOSE:To offer an original reading lens having such high brightness as F/No=3, such a wide angle as the half viewing angle of 30 deg., the numerical aperture of almost 100% up to a circumferential part, and high contrast. CONSTITUTION:A first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5 are arranged from an object side to an image side in that order, to obtain a retrofocus type. For correcting the aberration of divergence by the first lens, two lens surfaces are made aspheric surfaces.

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Inventors:

NISHINA KIICHIRO
HARADA NAOMI

Application Number:

JP41114990A

Publication Date:

August 06, 1992

Filing Date:

December 17, 1990

Export Citation:

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Assignee:

RICOH KK

International Classes:

G02B13/04; G02B13/18; G02B13/24; (IPC1-7): G02B13/04; G02B13/18; G02B13/24

Attorney, Agent or Firm:

Toru Kabayama (1 person outside)

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