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Implicit Control of Printhead Power

IP.com Disclosure Number: IPCOM000060839D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Wheeler, GL: AUTHOR

Abstract

This article defines a way to accurately maintain two different printhead power levels while only one level is monitored while printing. A representative electrophotographic printer engine illustrated in the figure consists of a photoreceptor 1, charge corona 2, printhead 3, electrostatic sensor 4, developer with toner replenisher 5, optical toner sensor 6, paper path 7, transfer corona 8, cleaner brush 9 and a microcomputer control system 10. To maintain a high level of print quality, the printhead 3must maintain a predetermined electrostatic image level on the photoreceptor 1. This is controlled by the printhead power level and monitored by the electrostatic sensor 4. Additionally, the toner replenisher system requires an accurately maintained predetermined electrostatic level which is reduced from that of the imaging level.

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Implicit Control of Printhead Power

This article defines a way to accurately maintain two different printhead power levels while only one level is monitored while printing. A representative electrophotographic printer engine illustrated in the figure consists of a photoreceptor 1, charge corona 2, printhead 3, electrostatic sensor 4, developer with toner replenisher 5, optical toner sensor 6, paper path 7, transfer corona 8, cleaner brush 9 and a microcomputer control system 10. To maintain a high level of print quality, the printhead 3must maintain a predetermined electrostatic image level on the photoreceptor 1. This is controlled by the printhead power level and monitored by the electrostatic sensor 4. Additionally, the toner replenisher system requires an accurately maintained predetermined electrostatic level which is reduced from that of the imaging level. The two required printhead power levels are subject to photoreceptor sensitivity and will change over photoreceptor life. The printhead imaging power level and the printhead toner replenisher power level will henceforth be referred to as the black level and the gray level, respectively. A microcode algorithm in conjunction with a microcontroller constitute the microcomputer 10. Before printing begins, switch A 13 and switch B 18 are both down. The value of the gray power level register 16 is adjusted until the electrostatic sensor output 4 equals the gray reference value 12 as determined by the comparator 14. At this time, register 16 is latched. Switches A and B are both switched up to set the black...