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ON PLATEN, DUAL PURPOSE AUTO MAGNIFICATION AND EXPOSURE CONTROL

IP.com Disclosure Number: IPCOM000025553D
Original Publication Date: 1986-Feb-28
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 88K

Publishing Venue

Xerox Disclosure Journal

Abstract

Figure 1 shows a portion of a document platen 10 of a xerographic copier. A document 12 is placed on the top surface of the platen. A platen cover 14 has located thereon a sensor 16. Sensor 16 contains a light emitter component which directs light rays onto the surface of document 12. A second lrght detecting component recelves rays reflected from the document and generates signals used to indicate the presence of a document and document density. These signals can be used to accomplish exposure control. A third function IS to determme if a document has been inadvertently left on the platen after a copying operation. The detailed circuitry of sensor 16 is shown in Figure 2.

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XEROX DISCLOSURE JOURNAL

ON PLATEN, DUAL PURPOSE AUTO
MACNXFICATION AND EXPOSURE CONTROL
James D. Rees
John A. Durbin

Proposed Classification
U.S. CI. 355/8 Int. Cl. G03g 15/28

- "'' 30 T/

Figure 1 shows a portion of a document platen 10 of a xerographic copier. A document 12 is placed on the top surface of the platen. A platen cover 14 has located thereon a sensor 16. Sensor 16 contains a light emitter component which directs light rays onto the surface of document 12. A second lrght detecting component recelves rays reflected from the document and generates signals used to indicate the presence of a document and document density. These signals can be used to accomplish exposure control. A third function IS to determme if a document has been inadvertently left on the platen after a copying operation. The detailed circuitry of sensor 16 is shown in Figure 2.

Volume 11 Number I January/February 1986 33

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ON PLATEN, DUAL PURPOSE AUTO MAGNIFICATION AND EXPOSURE CONTROL (Cant'd)

Turning now to Figure 2, sensor 16 comprises a light emitting diode 20 for transmitting light rays onto the surface of document 12. Phototransistor 22 detects the light rays reflected from the surface of document 12. Phototransistor 22 is coupled to a circuit indicated generally by the reference numeral 24. Circuit 24 inctudes a 2,000 ohm resistor 26 in series with a 5,000 ohrn variable resistor 28 which is used for sensitiv...