| 摘要 |
Electrophotographic process control in copiers and printers using test patches at different locations within the image frame. Test patches or areas are placed at various locations in subsequent frames to reduce any memory discontinuities encountered when high density areas are repeatedly placed at the same location within an image frame. The overall image frame includes a plurality of image or picture areas which contain unrelated information data and at least one these areas is replaced with a process test area in some or all of the subsequently produced frames. The test area includes several test strips of varying density which may also be positioned differently within the test area in subsequent frames. The variation in location of the test areas and the position of the test strips can be by random selection or by a predetermined pattern which places the areas and strips at several possible locations. The locations are communicated to the process controller so that appropriate sensors can properly monitor and measure the test patches.
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