| 摘要 |
PURPOSE:To surely detect register marks and to prevent color shifts by detecting the register mark on a transparent area provided in a moving means and correcting the position of an image on an image bearer based on a detection signal. CONSTITUTION:Sensitive drums 1Y, 1M and 1C for forming yellow, magenta and cyanegen images are driven in directions shown with arrows 5Y, 5M and 5C, united with worm wheels 2Y, 2M and 2C through worms 4Y, 4M and 4C. Optical boxes 6Y, 6M and 6C generate raster lines 7Y, 7M and 7C of laser light to expose the sensitive drums 1Y-1C. The images formed on the sensitive drums 1Y-1C in a Carlson process are sequentially superposed on an intermediate belt 8 to be transferred. Moreover, they are transferred to transfer paper 12 through rollers 10 and 13. The register marks 16a-16c and 17a-17c provided in the areas 8a and 8b consisting of a transparent film on the moving belt 8 are detected by two-dimensional pickup elements 14 and 15 through lenses 18 and 19 and the optical boxes 6Y-6C are controlled so as to be in correct postures with the detection signal.
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