Browse Prior Art Database

Toner Patch Sensing

IP.com Disclosure Number: IPCOM000039963D
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Bushaw, KA: AUTHOR [+4]

Abstract

In a computer-controlled xerographic reproduction device, toner is applied to a photoconductor's latent electrostatic image by a developer. This toner image is then transferred from the photoconductor to a sheet of paper, as a copy or print is produced. As a result, the concentration, or quantity, of toner in the developer decreases, and toner must be added to the developer to replace the toner being carried out of the developer on the photoconductor. For example, a normal copy sheet will consume about 25 mg of toner, whereas an extremely black copy sheet may consume as much as 150 mg of toner. Various types of toner concentration sensing apparatus exist, one of which is a patch sensor such as is shown in U.S. Patent 4,178,095.

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Toner Patch Sensing

In a computer-controlled xerographic reproduction device, toner is applied to a photoconductor's latent electrostatic image by a developer. This toner image is then transferred from the photoconductor to a sheet of paper, as a copy or print is produced.

As a result, the concentration, or quantity, of toner in the developer decreases, and toner must be added to the developer to replace the toner being carried out of the developer on the photoconductor. For example, a normal copy sheet will consume about 25 mg of toner, whereas an extremely black copy sheet may consume as much as 150 mg of toner. Various types of toner concentration sensing apparatus exist, one of which is a patch sensor such as is shown in U.S. Patent 4,178,095. In the patch-sensing apparatus of this disclosure the interval at which toner concentration is tested is decreased, and the quantity of toner which is fed to the developer is increased, when it is detected that toner concentration is becoming increasingly low, i.e., toner concentration is trending downward, to lower and lower concentrations as a number of patch sensor tests are made. In this apparatus, three output signals are possible from the patch sensor, i.e., toner concentration "OK", toner concentration "LOW", or toner concentration "EXTRA LOW". The sensing of toner concentration OK indicates to the computer that toner need not be added to the developer, whereas the sensing of LOW or EXTRA LOW indicates that toner must be added to the developer. The control algorithm provides that if a number of consecutive LOW signals are received, the control action of an EXTRA LOW signal is implemented.

If a number of consecutive EXTRA LOW signals are received, an error condition exists, in which case the reproduction device is prevented from making copies, but it continues to run, toner is added to the developer, and patch sensing continues, in an attempt to establish a toner concentration OK condition. However, this error condition is log...