| 摘要 |
PURPOSE:To take a copy of excellent picture quality by providing plural density measuring sensors for original density detection and selecting a part with the largest reflection factor, and varying copy density to a proper value automatically on the basis of it. CONSTITUTION:Density measuring sensors 4-6 detect the density of an original once operation starts, and the part with the largest reflection coefficient is selected to control an exposure lamp 3 so that the part is at the potential of the base of a copy. Outputs of signal photodetecting elements 4a-6a, and 4c-6c are supplied to amplifier correctors 11-13. Their outputs are supplied to multipliers 18-20. Signals from the density sensors 4 and 5 are supplied to a comparator 14 as signals to be employed. The comparator 14 inputs the signal of the part with the largest reflection factor to a computing element 15, and a control signal based upon it is sent out to an exposure lamp light source 17 through a driver 16 to set the proper quantity of exposure automatically. Consequently, even an original having extremely high density at one side is copied with good picture quality without any trouble. |
