PURPOSE: To increase the recording speed without changing whole density, by using only the specific nozzle part of a plurality of nozzle parts in the case of a high-speed motor and driving an ink droplet generating means so as to obtain a dot with a diameter suitable for dot density.
CONSTITUTION: A nozzle part 7 is filled with ink 8 and heaters 9, 10 are provided to the bottom part of the nozzle part 7. For example, when the heater 9 is turned ON, air bubbles 11 generate and an ink droplet 12 is emitted by the energy thereof. When both of heaters 9, 10 are turned ON, large air bubbles 13 generate and an ink droplet 14 larger than the ink droplet 12 is emitted. Hereupon, when the orifices of emitting nozzles are provided N orifices apart (N is positive integer) and the scanning speed is set to (N+1) times, dot density comes to 1/(n+1) and the recording speed can be set to (N+1) times. Further, it is desirable that the number of nozzles arranged to a head is integer-times of (N+1).
TAKADA YOSHIHIRO
OKUBO MASAHARU
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