Abstract: A main power supply is connected to a memory through a diode which is provided in such a manner as to allow the current to flow from the main power supply to the memory. An external power supply terminal is connected to a cathode terminal of the diode. The voltage supervising circuit supervises the level of the voltage of the main power supply by detecting the level of the voltage at the anode terminal of the diode. When the level of the voltage is below a specified level, a CPU retracts a date which is being processed to an external memory in accordance with a signal from the voltage supervising circuit.

Abstract: It is so constructed that the current flowing during the input waiting period is reduced. A pull-down resistor is connected to one electrode of X-axis electrodes. A diode is connected to one electrode of Y-axis electrodes along the Y-axis electrode direction. During the input waiting period, the anode terminal of the diode is set to a high level. The detection of the voltage variation of the X-axis electrode to which the resistor is connected is performed during the input waiting period. When the voltage variation is detected, the operation of detecting a position is started.

Abstract: A scan control circuit for detecting a stable scanning movement of a hand-held type printer over a copy paper includes an encoder for producing pulses in response to the scan movement of the hand-held type printer. The pulses are applied to a stable scan detector and also to a gate circuit. The stable scan detector detects a frequency of the pulses and produces an enable signal when the frequency exceeds a reference frequency. By the enable signal, the gate circuit is enabled to start counting the pulses. When the gate circuit counts a predetermined number of pulses, a power on signal is produced for starting the copy reproducing operation.

Abstract: An image reader of manual scan type for a portable copier is disclosed. The image reader comprises a reading head for scanning a document manually, memory means for storing image data read by the reading head, write control means for writing said image data into the memory means and a printer. The image reader further comprises image data processing means for adjusting image data obtained by the image sensor so as to form a noise free image upon writing image data into the memory means. Also the image data processing means operates to delete image data of a reference line indicative of a manual scan starting position.