COLOR REGISTRATION TECHNIQUE USING FLUORESCENT MARK ON PHOTORECEPTOR
Original Publication Date: 1994-Dec-31
Included in the Prior Art Database: 2004-Apr-07
Xerox Disclosure Journal
Electronic printers are known in the art wherein a plurality of successive color images are formed in superimposed registration on the surface of a photoreceptor and transferred as a color image to a copy media. Various techniques are known for registering the successive images including detecting toner registration marks on the photoreceptor surface or detecting the passage of apertures formed in non-image areas of the photoreceptor belt. Figure 1 shows another registration technique which uses the detection of strategically placed fluorescent marks on or in a photoreceptor. Images I1 through I are formed by a Raster Output Scanner (ROS), only one identified as ROS Q%eing shown. The ROS is modulated in conformance to input video signals to form an exposed image frame I4 which is subsequently developed, recharged and re-exposed with a second color image. The scan lines formed by the ROS must be in exact alignment in the scan (Y) and cross-scan (X) (process) direction in order that successive color images are exactly superimposed (registered). To accomplish this registration, in one embodiment, fluorescent patterns 10, 12 shown enlarged in Figure 2A,are imprinted on the top edge of belt 8. The patterns are excited by the ROS scan beam as the belt moves towards the ROS station in the process direction. An optical detector (not shown) senses the fluorescent wave length and sends a signal to control circuitry which compares the signal to a reference value and send the feedback signal to control ROS 4. Alternately, as shown in Figure 2B, strips of fluorescent material can be laid down along the edge of the belt wide enough so that the requisite marks can be created by the ROS. The fluorescent pattern is again sensed. In another embodiment, the fluorescent material can be self-radiating such as the organic radioluminescent lights.