Cleaning method and apparatus for an electrographic system
AssigneeInternational Business Machines Corporation
InventorWallace B. Larson
Life of this patent
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Abstract
A method and apparatus for cleaning residual toner from the surface of an imaging member in an electrographic imaging system which uses carrier means to transport toner by triboelectric forces to develop an electrostatic image on the imaging member. The pre-clean corona current is adjusted periodically during the lifetime of the carrier as necessary substantially to neutralize the charge on residual toner so that it may readily be removed by a rotating cleaning brush having substantially no charge thereon. Adjustment is in response to a periodically sensed aging characteristic, the charge density of the toner, such as at successive preselected operating time intervals representing increments of carrier useful lifetime. In this manner, cleaning efficiency is maintained.
Claims8
Apparatus for removing residual toner from the surface of an imaging member in an electrographic imaging system in which periodically replenished toner is transported by a carrier by triboelectric forces to develop an electrostatic image on a moving imaging surface, said apparatus comprising:
- brush means mounted for movement in a closed path and contacting said imaging surface to clean residual toner from said surface;
- pre-clean corona means mounted adjacent said imaging surface upstream of said brush means for producing a charge on said residual toner;
- means for sensing the charge density of the toner as a characteristic indicative of the aging of the carrier;
- and
- means operatively responsive to said charge density, as sensed, to vary the current to the pre-clean corona means as necessary to produce a charge substantially neutralizing the charge on the residual toner prior to contact by said brush means to maintain cleaning efficiency substantially constant as the carrier ages.
Cleaning apparatus for the surface of an imaging element is an electrophotographic imaging system which employs toner periodically replenished and transported by a carrier by triboelectric forces to develop an electrostatic image on an imaging surface of a re-usable photoconductive imaging element movable in a closed path, said cleaning apparatus including a pre-clean corona unit positioned adjacent said path to neutralize electrostatic charges on residual toner on the imaging element as it passes the corona unit, a power supply for the corona unit and a rotary cleaning brush positioned to contact the imaging element to remove the neutralized toner therefrom, characterized by
- means for sensing the charge density of the toner as a characteristic indicative of the aging of the carrier,
- means coupled to the power supply to vary the magnitude and sign of the current to the pre-clean corona unit in accordance with changes in charge density of the toner as sensed by said sensing means during aging of the carrier as necessary to substantially neutralize the electrostatic charge on the toner prior to contact by the brush to maintain substantially constant cleaning efficiency as the carrier ages.
A method of cleaning residual toner from from the surface of an imaging member in an electrographic imaging system of the type which uses carrier means to transport toner by triboelectric forces to develop an electrostatic image on the imaging member, said method comprising the steps of:
- sensing the charge density of the toner repeatedly during the lifetime of the carrier means, said charge density being a characteristic indicative of the aging of the carrier means;
- and
- adjusting the current to a pre-clean corona unit adjacent said imaging surface in response to the sensed charge density as necessary to cause said unit substantially to neutralize any electrostatic charge on the residual toner prior to contact by a cleaning brush on which there is substantially no charge, thereby to maintain cleaning efficiency substantially constant as the carrier ages.
Dependencies are inferred from the claim text.