Title:
PROJECTION LENS
Document Type and Number:
Japanese Patent JP2637317
Kind Code:
B2
Abstract:
PURPOSE: To obtain the compact projection lens which is used for a projection type TV and has a plastic lens shaped to have a small asphericity quantity and no inflection point and also has superior machinability and image forming performance.
CONSTITUTION: This projection lens consists of a 1st negative meniscus lens group L1, a 2nd positive lens group L2 which has a convex surface on a screen side, a 3rd positive lens group L3, a 4th positive biconvex lens group L4, a 5th positive weak lens group L5, and a 6th negative lens group L6 which has a concave surface on the screen side in order from the screen side, and the 2nd and 5th lens groups L2 and L5 have aspherical surfaces as both surfaces. At this time, the 2nd lens group L2 through which luminous flux with a large luminous flux diameter passes have no inflection point and is so shaped as to have a small asphericity quantity. Consequently, spherical aberration deterioration due to a shape error is prevented although specifications of a 1.05 aperture ratio and a 40 half-fieldangle are obtained, and the projection lens which has high-performance image formation characteristics and superior productivity is realized.
Inventors:
TODE HIDEKAZU
Application Number:
JP23474391A
Publication Date:
August 06, 1997
Filing Date:
September 13, 1991
Export Citation:
Assignee:
MITSUBISHI DENKI KK
International Classes:
G02B9/64; G02B13/16; G02B13/18; (IPC1-7): G02B9/64; G02B13/18
Domestic Patent References:
| JP339916A | ||||
| JP3235907A |
Attorney, Agent or Firm:
Maeda Minoru
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