Browse Prior Art Database

Programmed Copier Background Control and Key Operator Intervention

IP.com Disclosure Number: IPCOM000046167D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 35K

Publishing Venue

IBM

Related People

Brannan, RC: AUTHOR [+5]

Abstract

Compensation for increased copy background in a xerographic copier/ printer is provided by counting copies and shifting the charge corona grid voltage as threshold count levels are reached. The assignment of a password to the machine key operator allows the changing of the compensation levels as well as the intervention for control of other features previously available only to a Customer Engineer.

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Programmed Copier Background Control and Key Operator Intervention

Compensation for increased copy background in a xerographic copier/ printer is provided by counting copies and shifting the charge corona grid voltage as threshold count levels are reached. The assignment of a password to the machine key operator allows the changing of the compensation levels as well as the intervention for control of other features previously available only to a Customer Engineer.

Xerographic copies run in a copier set in the Darker Copy mode frequently produce objectionable background levels. As toner film, photoconductor fatigue and machine contamination become worse, the background also degrades. The background is controlled by advancing the photoconductor periodically, but this advancement is normally controlled based on background levels produced in normal copy modes. Control of copier grid voltage (dark charge) at four different levels (e.g., -860 V, -790 V, -720 V and -650 V) allows maintenance of the background level at a minimum during Darker Copy mode operations. An example of a power supply capable of providing such 70-volt shifts is [*]. Under normal conditions, all copies including those in Darker Copy mode are made at predetermined charge corona grid voltage, such as -860 V. When Darker Copy is selected, the corona grid voltage is controlled at levels depending on the number of copies made on that section of the photoconductor.

Reducing dark charge on the photoconductor as it ages controls background, yet adds desired contrast to faded documents, written documents or documents marked with light pencil, etc. The flowchart of the control is shown in Fig. 1. In the example shown, the grid voltage is reduced from -860 V to -790 V after 5,000 copies and further reduced to -720 V after l0,000 copies, at which level it is maintained until the photoconductor is replaced or incremented.

By assigning the key operator a password in a microcomputer-controlled copier or the like, the key op...