Browse Prior Art Database

METHOD FOR IMPROVING MAGNETIC TONER CONCENTRATION SENSORS

IP.com Disclosure Number: IPCOM000026778D
Original Publication Date: 1993-Aug-31
Included in the Prior Art Database: 2004-Apr-06
Document File: 2 page(s) / 100K

Publishing Venue

Xerox Disclosure Journal

Abstract

Because of the dynamic nature of a magnetic brush developer system, it is difficult to find a suitable location for a toner concentration sensor. Therefore, the toner concentration sensor is located adjacent to the magnetic brush in an active developer flow path so that changes in toner concentration can be sensed immediately. It is also desirable that the developer be either about 10 millimeters deep or that the developer be quite uniform in thickness. If not, variations in the depth of developer give erratic signals that can be confused with concentration signals. In magnetic brush developer housings, for example, the Xerox Corporation 5028'", the only location that meets the aforementioned requirements is in the bottom of the developer auger. However, the developer layer in the auger is only a few millimeters deep on average, and the thickness changes as the auger rotates. This causes a pulsating signal that requires processing before it can be used to monitor toner concentration. Of greater concern is that average depth in the auger can change erratically causing uncertainty in the toner concentration measurement. A method for improving the accuracy and repeatability of magnetic toner concentration sensors is achieved by removing one or more turns in the auger directly above the sensor. As shown in the Figure, a modified auger 1 having a sensor 2 and detection zone 3 and a removed or a missing vane 4 results in a toner lump region 5 directly over the detection zone 3. The modified auger causes the developer to rise in that portion of the auger having the missing vane creating a thick lump of developer. The lump is pushed through the vaneless region until caught by subsequent vanes. The absence of vanes in the sensing region giving rise to the lump of developer prevents pulsation in height and, therefore, prevents pulsation in signal strength and makes the sensor less sensitive to thickness variations.

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XEROX DISCLOSURE JOURNAL

METHOD FOR IMPROVING MAGNETIC TONER CONCENTRATION SENSORS John T. Bickmore

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Proposed Classification
U.S. C1.355/298 Int. C1. G03g 13/08

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XEROX DISCLOSURE JOURNAL - Vol. 18, No. 4 July/August 1993 419

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METHOD FOR IMPROVING MAGNETIC TONER CONCENTRATION SENSORS (Cont'd)

Because of the dynamic nature of a magnetic brush developer system, it is difficult to find a suitable location for a toner concentration sensor. Therefore, the toner concentration sensor is located adjacent to the magnetic brush in an active developer flow path so that changes in toner concentration can be sensed immediately. It is also desirable that the developer be either about 10 millimeters deep or that the developer be quite uniform in thickness. If not, variations in the depth of developer give erratic signals that can be confused with concentration signals. In magnetic brush developer housings, for example, the Xerox Corporation 5028'", the only location that meets the aforementioned requirements is in the bottom of the developer auger. However, the developer layer in the auger is only a few millimeters deep on average, and the thickness changes as the auger rotates. This causes a pulsating signal that requires processing before it can be used to monitor toner concentration. Of greater concern is that average depth in the auger can change erratically causing uncertainty in the toner co...