Browse Prior Art Database

Original Publication Date: 1995-Jun-30
Included in the Prior Art Database: 2004-Apr-07

Publishing Venue

Xerox Disclosure Journal


In a electrophotographic printing machine a developer unit is employed to develop a electrostatic latent image recorded on a photoconductive surface. Additional toner particles are furnished to the developer unit as the toner particles are depleted therefrom during the development process. It has been found that in addition to furnishing toner particles, it is highly desirable to furnish an additional supply of carrier granules to the developer housing sump. This significantly extends the life of the developer material. Degradation of the developer material occurs due to contaminates and debris intermingling therewith. The contaminants and debris are frequently lighter than the developer material and flow to the top thereof. In a developer material of the type hereinbefore described, extraneous developer unit must be removed from the sump thereof. This is achieved by having a stand pipe disposed in the housing of the developer unit. When the developer material level exceeds that of the stand pipe developer material flows over into the stand pipe and it is discharged from the developer housing. This maintains the developer material at a substantially constant level with the developer unit. Debris floating on the top of the developer material is frequently discharged through the stand pipe. This is highly desirable. However, in many instances when agitation of the developer material is minimized, the debris sinks to the bottom of the developer material and is not discharged through the stand pipe. In order to promote discharge of debris, it is necessary to facilitate the movement of the debris to the top of the developer material so as to discharge it through the stand pipe. By agitating the developer material, the lighter debris floats to the top of the developer material and is subsequently discharged through the stand pipe. One way to facilitate agitation of the developer material is to have electromagnets positioned around the stand pipe. This generates magnetic fields which induce agitation of the developer material.