PRECESSION SCANNING FOR ELECTRONIC DOCUMENT INPUT
Original Publication Date: 1992-Dec-31
Included in the Prior Art Database: 2004-Apr-06
Xerox Disclosure Journal
has a maximum document scanning speed o B 15 ips. In order to increase VR = VB - Vs Where VR is defined to be the desired scan speed. This requires that the instantaneous document speed VB be monitored by the scanhead carriage. The scanhead velocity Vs is then modulated according to this information such that VR remains constant. In this manner, the effective scan rate remains constant.
XEROX DISCLOSURE JOURNAL
PRECESSION SCANNING FOR Proposed Classification ELECTRONIC DOCUMENT INPUT U.S. C1.355/233 Steven R. Moore Int. Cl. G03g 15/28
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XEROX DISCLOSURE JOURNAL Vol. 17 No 6 ?iovember/December 1992 455
PRECESSION SCANNING FOR ELECTRONIC DOCUMENT INPUT(Cont'd)
Present technology for electronic copying usin an image input terminal (IIT)
throughput to 90 dpm, a document constant velocity transport (CVT) is required to pass originals documents past the stationary scanhead 9. A separate scanhead carriage is also required to allow book copying on the platen
8. Thus, two independent servo loops are required.
A better system includes applying precession scanning to the IIT thereby eliminating the need for a CVT. The primary advantage of precission scanning is the ability to raise the document speed above the scanning speed of 15 ips in order to improve document throughput. In practice and as shown in the Figure, the document transport belt 5 moves at an unregulated sped which has an average VB . The document 7 is assumed to have the same instantaneous speed as the document transport belt. The scanhead travels under the platen at a speed Vs . These two instantaneous speeds VB and Vs are related so that:
has a maximum document scanning speed o
B 15 ips. In order to increase
VR = VB - Vs
Where VR is defined to be the desired scan speed. This requires that the instantaneous...