Browse Prior Art Database

Folding Optics Design With Reduced Sensitivity to Vibration

IP.com Disclosure Number: IPCOM000044019D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Prakash, R: AUTHOR

Abstract

Pentamirrors and pentaprisms have been used in many types of optical instrumentation and electro-optical systems. They are preferred over a single mirror because they reduce mounting accuracy requirements and make a system insensitive to certain motions. The present article discloses replacing a single-element fold mirror by a two-element fold mirror, thereby greatly reducing the scan line problem. It can be used in a variety of printheads and scanners. In a typical electrophotographic printhead, scanning is achieved by a rotating polygon mirror, as illustrated in Fig 1. A modulated beam R1 strikes the rotating polygon mirror A, and is reflected as R2 . Due to manufacturing tolerances and misalignment in spindle bearings, the normal to mirror surface A does not necessarily lie in the XY plane.

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Folding Optics Design With Reduced Sensitivity to Vibration

Pentamirrors and pentaprisms have been used in many types of optical instrumentation and electro-optical systems. They are preferred over a single mirror because they reduce mounting accuracy requirements and make a system insensitive to certain motions. The present article discloses replacing a single- element fold mirror by a two-element fold mirror, thereby greatly reducing the scan line problem. It can be used in a variety of printheads and scanners. In a typical electrophotographic printhead, scanning is achieved by a rotating polygon mirror, as illustrated in Fig 1. A modulated beam R1 strikes the rotating polygon mirror A, and is reflected as R2 . Due to manufacturing tolerances and misalignment in spindle bearings, the normal to mirror surface A does not necessarily lie in the XY plane. Thus the reflected beam R2 (in vector form) has a variable Z component. This is referred to as tilt error. A well designed optic set B and D reduces this error to acceptable limits. Other sources of scan line problems are the folding optics (e.g., mirror C). Due to spindle and other sources of vibration, the mirror C experiences some motion. This causes the R4 ray to wander in undesirable fashion, i.e., over the angle shown in Fig. 1. The fold mirror experiences two types of motion due to vibration (Fig. 2). One is the rotational motion resulting in the normal vector N to jitter by WN. Second is the translational...