ON PLATEN, DUAL PURPOSE AUTO MAGNIFICATION AND EXPOSURE CONTROL
Original Publication Date: 1986-Feb-28
Included in the Prior Art Database: 2004-Apr-04
Xerox Disclosure Journal
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.