f-.theta. Lens for use in a light beam scanning device
AssigneeFuji Xerox Co., Ltd.
InventorAkira Ohta
Life of this patent
Estimating the term…
Abstract
An f.theta. lens for use in a light beam scanning device is constituted by a meniscus lens having a small power and located on the side of a deflection point, and a planoconvex lens having a large power and disposed with its convex surface on the side of a surface to be scanned. The lenses are constructed to satisfy the following conditions: -0.3.ltoreq.f/f1.ltoreq.0.2 (a) -0.6/f1+0.85/f.ltoreq.1/f2 1/f2.ltoreq.-0.6/f1+0.95/f (b) where f represents a focal length of a lens system constituted by the two lenses, and f.sub.1 and f.sub.2 respectively represent focal lengths of the meniscus lens and the plano-convex lens.
Claims1
An f.theta. lens for use in a light beam scanning device for focusing on a surface to be scanned a light beam which is deflected by deflecting means, said f.theta. lens comprising:
- a meniscus lens having a small power and located on the side of a deflection point which the light beam is deflected, and
- a plano-convex lens having a large power and disposed with its convex surface on the side of said surface to be scanned,
- said lenses being constructed to satisfy the following conditions:
- -0.3.ltoreq.f/f1.ltoreq.0.2 (a)
- -0.6/f1+0.85/f.ltoreq.1/f2
- 1/f2.ltoreq.-0.6/f1+0.95/f (b)
- where f represent a focal length of a lens system constituted by said two lenses, and f.sub.1 and f.sub.2 respectively represent focal lengths of the meniscus lens and the plano-convex lens.
Dependencies are inferred from the claim text.