| 摘要 |
A bar code scanner or reader 106 is used for automatic density control in electrostatographic copiers. A test patch composed of a succession of different voltage levels on a photoreceptor 104, (corresponding to lines of a bar code), are arranged in order that the number of lines developed to a visible state are used to produce proper development control. As an example, assuming five lines, the first three would be developed to visibility when toner concentration (developability) is normal, and only two lines developed to visibility if a standard addition of toner is needed. The presence of only one line might call for a larger-than-normal toner addition, and a count of zero or more than three lines trigger appropriate signals to the operator. The lines of various voltages could be generated in several ways, such as a small transparency or slitted screen 100 with a separate light source 102, a transparency intermittently introduced into the path of the exposure light, an opaque test patch adjacent the document area for exposure through a lens, or a small charging device intermittently energized to various voltages. <IMAGE> |
