Title:
PROJECTION LENS FOR PROJECTOR
Document Type and Number:
Japanese Patent JPH01188814
Kind Code:
A
Abstract:
PURPOSE:To obtain a high picture quality from the center of a picture to a periphery by providing at least one aspheric surface at a first group lens. CONSTITUTION:The title lens is composed of a first positive group lens having the almost refracting power of the whole system successively from a screen side, a second negative group lens to direct a concave surface to the screen side and a third negative group lens and at least one aspheric surface is provided at the first group lens. Thus, a projection lens for a projector which is loaded to the projector to use a cathode ray tube in which a fluorescent surface is a plane, in which an aperture ratio is about 1:1.1 and larger, a semi- field angle is also about 28 deg. and wide, respective aberrations are satisfactorily corrected including a color and the image with a high picture quality is obtained up to the periphery.
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Inventors:
UEDA KIICHIRO
Application Number:
JP1258188A
Publication Date:
July 28, 1989
Filing Date:
January 25, 1988
Export Citation:
Assignee:
KONISHIROKU PHOTO IND
International Classes:
G02B13/16; G02B13/18; H04N5/74; (IPC1-7): G02B13/16; G02B13/18; H04N5/74
Attorney, Agent or Firm:
Fumio Sato (2 others)