INK JET PRINTER

PURPOSE:To stabilize an ink jet head for a long period by a method wherein the ink jet head is driven for each certain frequency when a main power supply of an ink jet printer is off. CONSTITUTION:When a driving main power supply for an ink jet printer is turned on, a microprocessor 1 outputs a drive command to an ink jet head driver 7 based on a printing data, and makes an ink jet head 8 perform printing. Elapsed time T1 from a printing end time point under ON state of the main power supply is compared with operation frequency T2. When a T1>T2 state is reached, a drive command is outputted to the ink jet head driver 7, and the ink jet head 8 is prevented from clogging forcibly at a constant period. When the main power supply is turned off, power is turned on with a sub power supply 3 to start operation. Counted time of a timer counter CT which counts an operation period is compared with the operation period T2. When said values match each other, a drive pulse is outputted to the head driver 7 and ink is forcibly jetted from the ink jet head 8 to prevent clogging. This operation is performed until the main power supply is turned on.