Method to provide optimum optical contrast for registration mark detection

摘要

A method of achieving optimum optical contrast for detecting registration marks in a multicolor electrophotographic printing machine. The reflectivity of the image carrying member which is usually an intermediate transfer belt is determined. The reflectivity of each of the toners is then determined. If one of the toners has a contrasting reflectivity, while the remaining toners do not contrast then a uniform field of the contrasting toner is imaged and developed and the registration marks for the other toner colors are then developed on top of the uniform field. A void in the field in the shape of the other toner marks is used as the registration mark for the contrasting toner. If all of the toners have a contrasting reflectivity with the belt, the registration marks are imaged and developed directly on the belt.