Browse Prior Art Database

Maintaining Vertical Paper Registration in Printers

IP.com Disclosure Number: IPCOM000059770D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 15K

Publishing Venue

IBM

Related People

Heath, AW: AUTHOR

Abstract

With the advent of personal general-purpose computers, many office environments are using them with word processing software as part of a total office solution. Many retail stores sell the pieces that are joined together to make this system. The designers of the word processing package cannot possibly know all the printers that the end user might attach. The possible attachment choices become virtually unlimited. The problem is in the base printer technology. An OEM printer manufacturer may implement vertical indexing in various ways, depending on the mechanics of the printer design. A somewhat standard format is implemented for 6 and 8 lines per inch. Line densities of 5.3 and 24 lines per inch are also allowed.

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Maintaining Vertical Paper Registration in Printers

With the advent of personal general-purpose computers, many office environments are using them with word processing software as part of a total office solution. Many retail stores sell the pieces that are joined together to make this system. The designers of the word processing package cannot possibly know all the printers that the end user might attach. The possible attachment choices become virtually unlimited. The problem is in the base printer technology. An OEM printer manufacturer may implement vertical indexing in various ways, depending on the mechanics of the printer design. A somewhat standard format is implemented for 6 and 8 lines per inch. Line densities of 5.3 and 24 lines per inch are also allowed. Also, various combinations of the First Writing line and line spacing options can cause failure if only the 6- and 8-lines- per-inch controls can be used. Most printers have a Variable Line spacing control that lets the Text software system define exactly how many "steps" to move the paper. The distance that is moved by "one step", however, is not a standard. For example, many data processing printers will allow 1/72 of an inch as one step. Other word processing printers commonly use 1/48 or 1/96 of an inch for their base printer indexing units or steps. Some new entries into the market use 1/60 of an inch, and some all-points-addressable (APA) models use 1/120 or 1/180 of an inch. As demonstrated, there is no standard printer base for the fine vertical index increment. Previously, the text processing applications found a least common denominator (LCD) between the common text printers and data processing printers. This was adequate until the units started to deviate radically from 72nds, 48ths, and 96ths. The prior art LCD concept cannot be extended to handle all the printer base unit possibilities. As the least common denominator units become smaller to accommodate the variety of printers, more than 20 bits of information would be needed as there may be almost nothing to reduce the least common denominator. Most personal computers cannot easily handle binary numbers greater than 15 bits plus sign; thus, additional software overhead is needed. The new method employs the math concept of a rational number. Any value can be expressed as a ratio of 2 integer numbers. For example, one third of an inch is exactly specified by 1/3, whereas it cannot be exactly expressed as a decimal number (.333333333333....) as it is infinitely
repeating. Using this concept, the vertical position can be more simply expressed as a 16-bit position plus a rational number for the fractional difference in the base units. By picking a number that is small enough to be imperceptible to printed output and also a popular least common denominator, the results will adequately maintain vertical positioning over the course of many printed pages. The rational number is always the remainder that is not accoun...