DEVELOPER FLOW CONTROL ARRANGEMENT FOR A XEROGRAPHIC MACHINE
Original Publication Date: 1978-Oct-31
Included in the Prior Art Database: 2004-Mar-31
Xerox Disclosure Journal
Various systems are known to continually monitor toner con-centration and to replenish toner supply as required. The Automatic Development Control unit (ADC) shown in the figure contains an optical toner sensor arrangement which typically includes NESA plates on which toner is deposited. The ADC unit measures the optical density of the developer flowing through the ADC unit as well as the optical density of toner deposited on the MESA plates. In order to achieve an accurate measurement of the optical density of the developer flow, the flow must be steadily maintained, i.e., flow variations can be sensed as changes in the "developability" of the developer. A steady flow is accomplished by placing two cones, 4 and 6, one above the other. The outlet 8 of upper cone 4 should be lower than the top surface of lower cone 6, and the orifice diameter of outlet 8 should be larger than the orifice diameter of outlet 10 of lower cone 6. A typical design would also require that the lower cone 6 be flush with the ADC orifice 12 and have the same size opening. The cone wall angles should be steep relative to vertical with maximum angles of approximately 40°. Assuming the interior cone surfaces are sufficiently smooth and the upper cone is at least partially full at all times, a steady developer flow will be maintained into the ADC unit.