Patent ID: 7562954

Claim:
An inkjet printer comprising: an inkjet head that moves relative to a recording medium to perform printing, the inkjet head including, a flow path unit including a plurality of pressure chambers respectively communicating with a plurality of ink ejection ports that ejects ink droplets toward the recording medium, and a piezoelectric actuator configured to take a first state where a volume of the pressure chamber is to be V 1 , and a second state where the volume of the pressure chamber is to be V 2 larger than V 1 ; and a controller that supplies a drive pulse signal to the piezoelectric actuator in order to repeat an operation in which the piezoelectric actuator transits from the first state to the second state and returns to the first state, during a printing period required for the recording medium and the inkjet head to relatively move by a unit distance corresponding to a resolution of the printing, for enabling the corresponding ink ejection port to eject a plurality of ink droplets at an ejecting speed, wherein the controller supplies the drive pulse signal so that the following relationships are satisfied, 4.5 AL≦A+B+C ≦5.4 AL, 2.60AL≦B≦3.35AL, and 0.81AL≦C≦1.14AL, where AL represents a time period from a time when a transition from the first state to the second state is started, to a time when a return from the second state to the first state is started, causing the ejecting speed to be maximum, A represents a time period from a time when a first transition from the first state to the second state is started, to a time when a first return from the second state to the first state is started, during the printing period, B represents a time period from the time when the first return from the second state to the first state is started, to a time when a second transition from the first state to the second state is started, during the printing period, C represents a time period from the time when the second transition from the first state to the second state is started, to a time when a second return from the second state to the first state is started, during the printing period.