Liquid ejection head

1. A liquid ejection head, comprising:

a nozzle plate including nozzles for ejecting liquid;

a plurality of pressure chambers communicating with the nozzles;

a plurality of actuators configured to vary the volume of the pressure chambers according to drive signals applied thereto; and

a drive circuit configured to generates drive signals for driving the plurality of actuators, wherein

the drive circuit generates a drive signal including an ejection waveform for an actuator with an expansion potential difference change that changes in stages and a contraction potential difference change that changes in stages, and sets the timing of the stages to cancels the vibration of an acoustic resonance frequency in a frequency range higher than a main acoustic resonance frequency of a liquid in the pressure chamber.

2. The liquid ejection head according to claim 1 , wherein the number of stages in the expansion potential difference change is equal to the number of stages in the contraction potential difference change.

3. The liquid ejection head according to claim 1 , wherein the magnitude of the expansion potential difference change is equal to the magnitude of the contraction potential difference change.

4. The liquid ejection head according to claim 1 , wherein the stages are equal voltage increments in magnitude.

5. The liquid ejection head according to claim 1 , wherein

the number of stages in the expansion potential difference change is two, and

the number of stages in the contraction potential difference change is two.

6. The liquid ejection head according to claim 1 , wherein

the number of stages in the expansion potential difference change is three, and

the number of stages in the contraction potential difference change is three.

7. The liquid ejection head according to claim 1 , wherein

when the period of the acoustic resonance frequency is λn and the number of stages in each of the expansion and contraction potential difference changes is h, an i-th stage is any one of the h stages, and a j-th stage is another one of the h stages after the i-th stage, then the time interval Tij between the i-th potential difference change start time and the j-th potential difference change start time satisfies the relationship:

(k/2−1/6)λn≤Tij≤(k/2+1/6) λn, when k is an odd number of 1 or more.

8. The liquid ejection head according to claim 7 , wherein the time interval Tij satisfies the relationship:

( k/ 2−1/6)λ n≤Tij≤kλn/ 2.

9. The liquid ejection head according to claim 1 , wherein the acoustic resonance frequency is an odd multiple of approximately three times or more of the main acoustic resonance frequency.

10. The liquid ejection head according to claim 1 , wherein the drive circuit includes a switching circuit connecting electrodes of the actuator to a voltage source and generates the drive signal by switching of the switching circuit.

11. A liquid ejection apparatus, comprising:

an actuator configured to vary the volume of a pressure chamber according to drive signals applied thereto; and

a drive circuit configured to supply drive signals for driving the actuator, wherein

the drive circuit generates a drive signal including an ejection waveform for the actuator with an expansion potential difference change that changes in stages and a contraction potential difference change that changes in stages, and sets the timing of the stages to cancels the vibration of an acoustic resonance frequency in a frequency range higher than a main acoustic resonance frequency of a liquid in the pressure chamber.

12. The liquid ejection apparatus according to claim 11 , wherein the number of stages in the expansion potential difference change is equal to the number of stages in the contraction potential difference change.

13. The liquid ejection apparatus according to claim 11 , wherein the magnitude of the expansion potential difference change is equal to the magnitude of the contraction potential difference change.

14. The liquid ejection apparatus according to claim 11 , wherein the stages are equal voltage increments in magnitude.

15. The liquid ejection apparatus according to claim 11 , wherein

the number of stages in the expansion potential difference change is two, and

the number of stages in the contraction potential difference change is two.

16. The liquid ejection apparatus according to claim 11 , wherein

the number of stages in the expansion potential difference change is three, and

the number of stages in the contraction potential difference change is three.

17. The liquid ejection apparatus according to claim 11 , wherein

when the period of the acoustic resonance frequency is λn and the number of stages in each of the expansion and contraction potential difference changes is h, an i-th stage is any one of the h stages, and a j-th stage is another one of the h stages after the i-th stage, then the time interval Tij between the i-th potential difference change start time and the j-th potential difference change start time satisfies the relationship:

(k/2−1/6)λn≤Tij≤(k/2+1/6) λn, when k is an odd number of 1 or more.

18. The liquid ejection apparatus according to claim 17 , wherein the time interval Tij satisfies the relationship:

( k/ 2−1/6)λ n≤Tij≤kλn/ 2.

19. The liquid ejection apparatus according to claim 11 , wherein the acoustic resonance frequency is an odd multiple of approximately three times or more of the main acoustic resonance frequency.

20. The liquid ejection apparatus according to claim 11 , wherein the drive circuit includes a switching circuit connecting electrodes of the actuator to a voltage source and generates the drive signal by switching of the switching circuit.