Browse Prior Art Database

Original Publication Date: 1977-Aug-31
Included in the Prior Art Database: 2004-Mar-30

Publishing Venue

Xerox Disclosure Journal


In an electrophotographic printing machine, it is desirable to maintain the concentration of toner particles within the developer mix substantially constant to optimize copy quality. A control system for achieving the foregoing is depicted in •the drawing. As shown therein, an"opaque timing wheel has a plurality of slits therein, The timing wheel synchronizes the machine Operation and has two channels of information. One channeL has a slot to indicate the initiation of each machine cycle. The Other channel has a plurality of slots indicating the location of the phôtoconductive drum during each cycle. The timing wheel is mounted' on the shaft of the photoconduc-tive drum and. has a light source positioned on One side there-of with the photosensor being positioned on the other' side thereof. The• tight source is arranged to transmit light rays through the slots • These light rays excite the photosensor which develops a signal' in responSe thereto. Digital filter and multiplex 62 detects the incoming signals and distinguish them free incorrect signals and transients. All inputs are polled and tested. During the 'polling of the signal, the • signal is.tested a plurality of times. A change in the signal in any one of these tests indicates that the signal is unre-liable and the 'signal 'is ignored. If the input signal is the • same for, all of the tests, the information is accepted and multiplexed 'onto an information bus and then decoded 'by