Abstract: Disclosed is an ink jet printer in which an ink is continuously spouted through a nozzle and divided into ink droplet. The ink droplets are selectively charged by supplied pulse voltages. After the supply of a prescribed charging voltage to a charging electrode is stopped, a voltage lower than the charging voltage is supplied to the electrode. Consequently, the ink droplets destined to land on a recording medium is prevented from making any deflected movement and from ginving rise to secondary dots. During the intitial period of the supply of the charging voltage to the charging electrode, a voltage higher that the normal charging voltage is supplied to preclude the occurrence of ink droplets of an intermediate potential due to a time lag between the time the voltage is supplied to the charging electrode and the time the ink droplets are electrically charged. Any attempt at heightening the operating speed of the printer entails no occurrence of secondary dots.

Abstract: An electric exposure meter for storing the brightness of a photographic object as an electric voltage of a magnitude corresponding thereto in order to control the exposure time by using the voltage thus stored.