Browse Prior Art Database

ROTATIONAL MIRROR FLAT PLATEN TO DRUM SCANNING SYSTEM

IP.com Disclosure Number: IPCOM000023684D
Original Publication Date: 1978-Oct-31
Included in the Prior Art Database: 2004-Mar-31
Document File: 2 page(s) / 252K

Publishing Venue

Xerox Disclosure Journal

Abstract

The rate at which copies can be produced depends on the rescan time for a given process speed. Efforts made to minimize this time in the past have been limited by the inertia of scan element. One successful low inertia device has been the use of a rotational mirror with a curved platen surface. The disadvantage of this system is the requirement for the curved platen surface. Various schemes proposed in the past have suffered from defects of focus caused by tilted image planes or incorrect conjugate.

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Page 1 of 2

XEROX DISCLOSURE JOURNAL

ROTATIONAL MIRROR FLAT PLATEN TO
DRUM SCANNING SYSTEM
David K. Shogren

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Proposed Classification
U.S. Cl. 355/7
mt. Cl. G03g 15/00

The rate at which copies can be produced depends on the rescan
time for a given process speed. Efforts made to minimize this
time in the past have been limited by the inertia of scan
element. One successful low inertia device has been the use
of a rotational mirror with a curved platen surface. The
disadvantage of this system is the requirement for the curved
platen surface. Various schemes proposed in the past have
suffered from defects of focus caused by tilted image planes
or incorrect conjugate.

To correct for defect of focus, reference is made to Figure 1.
Mirror 1 rotates about an axis through its surface and paral-
lel to the platen. The object distance thus is increased by
L/cos 0 and the image field tilted by 0. To correct the field
tilt, the lens is rotated by 0/2 producing an image plane
parallel to the ~rum tangent plane. The overall conjugate is
changed by L - L while the optical path is changed by (L + F +

x)cos 0 - CL + F + x). To maintain correct overall conjugate,

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Volume ~ Number 5 September/October 1978 347

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Page 2 of 2

ROTATIONAL MIRROR FLAT PLATEN TO DRUM SCANNING SYSTEM (Cont~d)

the focal length of the lens is varied (zoomed) by the rela~ tionship:

FL*= F+x+L

(m + 1) +(m + 1) m

Synchronously with the change in focal length, the lens position is...