Patent US4911928A successfully refreshed from Google Patents.
EP0299474A2
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Telecentric image-forming optical system for large image size
Assignee: Dainippon Screen Manufacturing Co Ltd
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Filing: 1988-07-14
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Granted: —
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Expires: 2008-07-14
Abstract
Abstract A telecentric image-forming optical system comprises: a first lens group including a double-convex lens (r₁, r₂), a meniscus lens (r₃, r₄) whose convex side faces an object or a plano-convex lens, and a double-concave lens (r₅, r₆) arranged in this order; and a second lens group including a double-convex lens (r₁₃, r₁₄), a meniscus lens (r₁₁, r₁₂) whose convex side faces an image or a plano-convex lens, and a double-concave lens (r₉, r₁₀) arranged in this order. The secondary focal point of the first lens group and the principal focal point of the second lens group substantially coincide in the vicinity of a double-convex lens (r₇, r₈). The telecentric image-forming optical system is compact and forms a large-sized image for its optical length.
Inventors
- 👤 Zenji Dainippon Screen Mfg. Co.Ltd. Wakimoto
- 👤 Takahisa Dainippon Screen Mfg. Co. Ltd. Hayashi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 11:15
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/22
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
103 words
A telecentric image-forming optical system, comprising a first lens group including a double-convex lens, a meniscus lens whose convex side is arranged to face an object or a plano-convex lens, and a double-concave lens and a second lens group including a double-convex lens, a meniscus lens whose convex side is arranged to face an image or a plano-convex lens, and a double-concave lens, in which system the secondary focal point of the first lens group and the principal focal point of the second lens group substantially coincide in the vicinity of a central double-convex lens disposed between the first and second lens groups.
Claim 2
Dependent Claim
103 words
A telecentric image-forming optical system, comprising a first lens group including a double-convex lens, a meniscus lens whose convex side is arranged to face an object or a plano-convex lens, and a double-concave lens and a second lens group including a double-convex lens, a meniscus lens whose convex side is arranged to face an image or a plano-convex lens, and a double-concave lens, in which system the secondary focal point of the first lens group and the principal focal point of the second lens group substantially coincide in the vicinity of a central double-convex lens disposed between the first and second lens groups.
Claim 3
Dependent Claim
37 words
A telecentric image-forming optical system according to claim 1, wherein lenses of at least one of the lens groups are cemented together with a glass material having a different refractive index and dispersive power from the lenses.
Claim 4
Dependent Claim
30 words
A telecentric image-forming optical system according to claim 1, wherein the secondary focal point of the first lens group coincides with the primary focal point of the second lens group.
Claim 5
Dependent Claim
27 words
A telecentric image-forming optical system according to claim 3, wherein the construction of the first lens group is same as the construction of the second lens group.
Claim 6
Dependent Claim
49 words
A telecentric image-forming optical system according to claim 3 or 4, wherein the position at which the focal points substantially coincide is shifted so that the double-convex lens disposed between the first and second lens group has an image-forming magnification other than 1.0 and/or the magnification thereof is varied.
Claim 7
Dependent Claim
41 words
A telecentric image-forming optical system according to claim 1, wherein the focal point of the first lens group and the focal point of the second lens group are different from each other so that the image-forming magnification is other than 1.0.
Claim 8
Dependent Claim
49 words
A telecentric image-forming optical system according to claim 6, wherein the dimension of the optical system of the second lens group is changed in proportion to the dimension of the optical system of the first lens group and has the same construction as that of the first lens group.
Claim 9
Dependent Claim
28 words
A telecentric image-forming optical system according to claim 3 or 6, wherein the construction of the first lens group is different from that of the second lens group.
Claim 10
Independent Claim
153 words
An apparatus for reading an original document by scanning said original document, using a scanning head which comprises an illuminating optical system for illuminating the original document, a solid state image sensor, and an image-forming system for converging a light flux reflected from the original document on the solid image sensor, the image-forming optical system including a telecentric image-forming optical system comprising a first lens group including a double-convex lens, a meniscus lens whose convex side faces the original document or a plano-convex lens and a double-concave lens and a second lens group including a double-convex lens, a meniscus lens whose convex side faces the solid image sensor or a plano-convex lens and a double-concave lens, the secondary focal point of the first lens group and the principal focal point of the second lens group substantially coinciding in the vicinity of a central double-convex lens disposed between the first and second lens groups.
Claim 11
Independent Claim
153 words
An apparatus for reading an original document by scanning said original document, using a scanning head which comprises an illuminating optical system for illuminating the original document, a solid state image sensor, and an image-forming system for converging a light flux reflected from the original document on the solid image sensor, the image-forming optical system including a telecentric image-forming optical system comprising a first lens group including a double-convex lens, a meniscus lens whose convex side faces the original document or a plano-convex lens and a double-concave lens and a second lens group including a double-convex lens, a meniscus lens whose convex side faces the solid image sensor or a plano-convex lens and a double-concave lens, the secondary focal point of the first lens group and the principal focal point of the second lens group substantially coinciding in the vicinity of a central double-convex lens disposed between the first and second lens groups.
Claim 12
Dependent Claim
23 words
An apparatus for reading an original document according to claim 9, wherein the scanning head scans the original document along a comb-shaped path.
Claim 13
Dependent Claim
35 words
An apparatus for reading an original document according to claim 9 or 10, wherein the original document is a block copy layout sheet and the scanning width of the scanning head is more than 30mm.
References Cited (Backward Citations)
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