| 摘要 |
PURPOSE:To attain stable control for a picture read output with respect to luminous quantity change over a wide range while keeping the data transfer period constant by inhibiting the storage for a prescribed reset period in storing an electric charge in response to a lighting light reflected in an original face. CONSTITUTION:An exposure time control circuit 10 resets a CCD 2 for a degree of time, for example, at the beginning to keep the state not storing an electric charge and releases the resetting from a certain point of time in a prescribed timing to store the electric charge, thereby controlling the exposure time of the CCD 2 in the method above. The data transfer period in this case is always constant independently of the exposure time of the CCD 2. Thus, the picture read output is stabilized even against the indirect luminous quantity change relating to the paper feed speed.
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