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Toner Patch Sensing - 'Toner Runaway' Compensation

IP.com Disclosure Number: IPCOM000099377D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Bonvallet, JC: AUTHOR [+4]

Abstract

Disclosed is a method of preventing toner control system instability when toner patch ratio is used to control developer toner concentration in an electrophotographic machine. The method compensates for measurement errors induced by high toner dust situations.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Toner Patch Sensing - 'Toner Runaway' Compensation

       Disclosed is a method of preventing toner control system
instability when toner patch ratio is used to control developer toner
concentration in an electrophotographic machine.  The method
compensates for measurement errors induced by high toner dust
situations.

      Toner patch sensing is often used to control the toner
concentration in a dual component developer mix.  A toner patch is
developed onto the photoconductor surface and the ratio of
untoned-to-toned photoconductor reflectance is compared to a desired
control ratio in order to select a toner replenishment rate for the
developer mix.  Under unusual situations, the untoned photoconductor
may become contaminated with toner dust which reduces the toner patch
ratio and improperly increases the toner replenishment rate.
Increased toner replenishment causes the contamination condition to
worsen, thus creating an unstable control situation.  The technique
described below detects the contamination and corrects the toner
patch ratio calculation such that the instability will not occur.
DETECTION OF THE RUNAWAY CONDITION Toner patch sensing is commonly
performed using a technique that increases or decreases the replenish
rate in an attempt to keep the toner patch RATIO constant.  The toner
patch ratio is calculated from toner patch sensor reflectance
measurements using the following relationship:

      RATIO = Vref / Vtoned where:    Vtoned = Signal from toned
photoconductor

      Vref   = Reference signal from untoned photoconductor

      Toner runaway occurs when the toner dust level on the
photoconductor increases to the point that it begins reducing the
reference signal from untoned photoconductor. This reduces the toner
patch ratio and causes the toner control system to replenish toner.
This additional t...