Lens system for projecting images of microfilm
AssigneeMinolta Camera Kabushiki Kaisha
InventorsSatoshi Iwasaki, Toshihiko Ueda, Kunihiko Konoma
Life of this patent
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Abstract
There is disclosed a lens system for projecting images of microfilm onto a screen or the like. The lens system is characterized by five lens components, that is, a first positive meniscus lens component convex to the magnification side, a second negative meniscus lens component concave to the magnification side, a third biconvex lens component, a fourth biconcave lens component having a powerful concave surface faced to the magnification side, and a fifth biconvex lens component.
Claims17
A lens system for projecting images of microfilm comprising from the magnification side to the reduction side,
- a first lens component of a positive meniscus lens component convex to the magnification side,
- a second lens component of a negative meniscus lens component concave to the magnification side,
- a third lens component of a biconvex lens component,
- a fourth lens component of a biconcave lens component having a powerful concave surface faced to the magnification side, and
- a fifth lens component of a biconvex lens component, wherein said lens components are respectively spaced from each other on an optical axis.
A lens system for projecting images of microfilm comprising from the magnification side to the reduction side,
- a first lens component of a positive meniscus lens component convex to the magnification side,
- a second lens component of a negative meniscus lens component concave to the magnification side,
- a third lens component of a biconvex lens component,
- a fourth lens component of a biconcave lens element having a powerful concave surface faced to the magnification side, and
- a fifth lens component of a biconvex lens component, wherein the lens system fulfills following conditions:
- 0. 9.ltoreq.TL/f.ltoreq.1.1
- 0.6.ltoreq..epsilon.d/f.ltoreq.0.7
- wherein f represents a total focal length, .epsilon.d represents a length of an optical axis from the frontmost lens surface to the rearmost lens surface of the lens system, and TL represents the sum of .epsilon.d described above with a lens back focal length at an infinite focussing condition.
A lens system for projecting images of microfilm comprising from the magnification side to the reduction side:
- a first lens component of a positive meniscus lens component convex to the magnification side;
- a second lens component of a negative meniscus lens component concave to the magnification side;
- a third lens component of a biconvex lens component;
- a fourth lens component of a biconcave lens element having a powerful concave surface faced to the magnification side, and
- a fifth lens component of a biconvex lens component;
- wherein the lens system fulfills the following conditions:
- ##EQU5## wherein, f represents a total focal length, f.sub.1 and f.sub.4 represent focal lengths of first and fourth lens components, respectively, and .nu..sub.1, .nu..sub.2, .nu..sub.3 and .nu..sub.4 represent the Abbe numbers of the first through fourth lens components, respectively.
A lens system for projecting images of microfilm consisting of from the magnification side to the reduction side:
- a first lens component of a positive meniscus lens component convex to the magnification side;
- a second lens component of a negative meniscus lens component concave to the magnification side;
- a third lens component of a biconvex lens component;
- a fourth lens component of a biconcave lens component having a powerful concave surface faced to the magnification side, and
- a fifth lens component of a biconvex lens component.
Dependencies are inferred from the claim text.