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Facsimile Scanner

IP.com Disclosure Number: IPCOM000077845D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 47K

Publishing Venue

IBM

Related People

Cassada, TE: AUTHOR [+2]

Abstract

A number of methods of reproducing scanned facsimile data, such as in an ink jet printing system, employ a microraster technique. Using conventional scanning techniques, a large buffer would be needed to store the scanned data so that it may be formatted into the microraster mode. The scanning technique described eliminates the need for buffering, relaxes the horizontal scan-speed requirement of the scanner, and results in no appreciable loss in achievable data compression.

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Facsimile Scanner

A number of methods of reproducing scanned facsimile data, such as in an ink jet printing system, employ a microraster technique. Using conventional scanning techniques, a large buffer would be needed to store the scanned data so that it may be formatted into the microraster mode. The scanning technique described eliminates the need for buffering, relaxes the horizontal scan-speed requirement of the scanner, and results in no appreciable loss in achievable data compression.

An entire page can be scanned in the same time duration as a conventional system while operating at a drastically reduced linear rate of travel. Compatibility with a microraster printer method, such as an ink jet system, is insured with no scan line "buffering for formatting" necessary. A large buffer, previously required, is eliminated.

Most high-speed facsimile systems employ a scanning method which horizontally sweeps the document. If a single pickup is used, there are strict timing requirements placed upon the hardware due to the speed at which the head must sweep across the page. Multiple scanners can be used to sweep in a horizontal manner requiring a large buffer for storage.

Essentially the same problem is apparent at the printing end. One of the best ways of printing is by using a microraster. A microraster pattern like the one used by a ink jet printer is shown in Fig. 1. Basically the method consists of generating a voltage ramp to deflect a stream of ink to the maximum character height. This ramp is then blanked or unblanked, depending on whether a dot is desired at that particular place of the character.

If a conventional scanner is used for scanning data to be reproduced by an ink jet printer, a large buffer would be required to store sufficient scans to generate the microraster format. For example, at 125 lines per inch resolution, a normal character would occupy a box 20 dots high by 13 dots wide. At 1000 characters per line, 20 lin...