Browse Prior Art Database

Redundancy for Document Scanners

IP.com Disclosure Number: IPCOM000052123D
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Craig, WJ: AUTHOR

Abstract

This article teaches that a redundant array can be added to a scanning array to improve reliability, image quality, array yield, and field maintenance.

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Redundancy for Document Scanners

This article teaches that a redundant array can be added to a scanning array to improve reliability, image quality, array yield, and field maintenance.

The invention comprises two image scanning devices 11 and 12, arranged in parallel and feeding respective offset gain compensation circuits 13 and 14. The signals from both offset gain compensation circuits 13 and 14 feed into an analog multiplexer 15 which has an output 16 leading to an analog-to-digital (A/D) converter 17. The analog multiplexer 15 is controlled by a control circuit 18. It will be assumed that the arrays 11 and 12 both contain defects in various locations but that they do not contain a defect in the same location.

The mirror imaging technique known in the prior art is utilized to place the same image on the two different devices 11 and 12. Thus, the devices 11 and 12 can be utilized to assure that a full image is received even though one or both of the devices may be partially defective. By selective switching between the two offset gain compensation circuits by means of the analog multiplexer, a perfect image is fed via line 16 to the A/D converter 17.

The control circuit 18 is utilized to control the analog multiplier 15 and would be programmed during the black-white calibration scan that is performed at the beginning of each document.

This permits the utilization of partially good scanning devices but at the same time removes dark signal and photo-response non...