Abstract Described herein is a projection lens system, comprising from the screen side a positive first lens unit of weak power consisting of a plastic meniscus, a positive or negative second lens unit of weak power consisting of a plastic lens element, third and fourth lens units in the form of a cemented glass lens having a positive combined focal length, a positive fifth lens unit of strong power, a positive sixth lens unit of weak power consisting of a plastic lens element, and a negative seventh lens unit having a concave surface on the screen side, each of the first, second, sixth and seventh lens units having at least an aspheric surface, and arranged to satisfy the following conditions 0.08<f/f.sub.1 <0.18 and (1) 0.01<|f/f.sub.2 |<0.1 (2) where f 1 and f 2 are focal lengths of the first and second lens units and f is the overall focal length of the projection lens system as a whole.
Inventors
👤 Takeshi Matsumura
👤 Noboru Koizumi
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-11-01 15:09
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/18; G02B13/16
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
151 words
A projection lens system, comprising from a screen side a positive first lens unit of weak power consisting of a plastic meniscus, a second lens unit of weak power consisting of a plastic lens element, third and fourth lens units in the form of a cemented glass lens having a positive combined focal length, a positive fifth lens unit of strong power, a positive sixth lens unit of weak power consisting of a plastic lens element, and a negative seventh lens unit having a concave surface on the screen side, each of said first, second, sixth and seventh lens units having at least an aspheric surface, and arranged to satisfy the following conditions 0.08<f/f.sub.1 <0.18 and (1) 0.01<|f/f.sub.2 |<0.1 (2) where f 1 and f 2 are focal lengths of said first and second lens units and f is the overall focal length of said projection lens system as a whole.
Claim 2
Dependent Claim
151 words
A projection lens system, comprising from a screen side a positive first lens unit of weak power consisting of a plastic meniscus, a second lens unit of weak power consisting of a plastic lens element, third and fourth lens units in the form of a cemented glass lens having a positive combined focal length, a positive fifth lens unit of strong power, a positive sixth lens unit of weak power consisting of a plastic lens element, and a negative seventh lens unit having a concave surface on the screen side, each of said first, second, sixth and seventh lens units having at least an aspheric surface, and arranged to satisfy the following conditions 0.08<f/f.sub.1 <0.18 and (1) 0.01<|f/f.sub.2 |<0.1 (2) where f 1 and f 2 are focal lengths of said first and second lens units and f is the overall focal length of said projection lens system as a whole.
Claim 3
Dependent Claim
65 words
A projection lens system as defined in claim 1, further satisfying the condition of 0.3<d.sub.1+2+3+4 /d<0.4 (3) d 1+2+3+4 is the sum of on-axis spacings between the screen side surfaces of said first and third lens units and d is the sum of on-axis spacings between the screen side surface of said first lens unit and a CRT side surface of said seventh lens unit.
Claim 4
Dependent Claim
26 words
A projection lens system as defined in claim 1 or 2, wherein said lens units are supported by a lens barrel of a synthetic resin material.