frequency used when continuous dots are printed to a predetermined value a stable jetting becomes possible and jetting speeds and volumes of second ink droplets and subsequent droplets may be prevented from being fluctuated a frequency of a jet pulse signal applied to an actuator in accordance with a printing command of a plurality of consecutive dots is set to be a reciprocal of the product of a sum and the time t in which a pressure wave propagates within an ink chamber in one propagation direction thus it is possible to prevent speeds and volumes of the second ink droplets and subsequent ink droplets from being fluctuated application_number US 20190898 A description a preferred embodiment of the present invention will hereinafter be described with reference to the drawings an exemplary arrangement of a mechanical portion of the apparatus for jetting droplets of ink according to this embodiment is illustrated in fig8 a and 8b and therefore need not be described exemplary sizes of a present ink droplet jetting apparatus 600 will now be described a length l of an ink chamber 613 may be for example 15 mm a size of a nozzle 618 is such that a diameter of an ink drop jetting side is for example 40 u03bcm a diameter of an ink chamber 613 side.