Liquid ejection apparatus, drive circuit thereof, and drive method thereof

1. A liquid ejection apparatus comprising:

a plurality of pressure chambers;

an actuator disposed between the pressure chambers and which is operated by electric charging/discharging to thereby apply pressures for introducing a liquid into the pressure chambers and ejecting a liquid from the pressure chambers, to the pressure chambers;

a drive circuit which outputs a direct current drive voltage having positive and negative potentials relative to a ground potential, causing the actuator to electrically charge/discharge;

a first electrode which applies the positive potential of the direct current drive voltage to one end of the actuator; and

a second electrode which applies the negative potential of the direct current drive voltage to the other end of the actuator.

2. The apparatus of claim 1 , wherein

the actuator is made of a pair of piezoelectric elements with polarization directions opposed to each other, and

the pair of piezoelectric elements form a wall partitioning the plurality of pressure chambers from one another.

3. The apparatus of claim 2 , wherein

the pair of piezoelectric elements is disposed along a direction that is perpendicular to an arrangement direction of the plurality of pressure chambers.

4. The apparatus of claim 1 , further comprising:

an insulating film which covers a surface of each of the electrodes, so as to prevent the electrodes from making contact with the liquid in each of the pressure chambers.

5. The apparatus of claim 1 , further comprising:

a nozzle plate which comprises a plurality of nozzles for ejecting the liquid, each nozzle disposed at a position corresponding to one of the pressure chambers.

6. The apparatus of claim 5 , further comprising:

a mask plate which is provided on the nozzle plate and is grounded.

7. The apparatus of claim 1 , wherein

the drive circuit comprises:

first and second direct-current power supplies which are connected in series to each other and have an interconnection point grounded;

a first switch circuit which comprises a serial circuit and a third switch, the serial circuit connecting first and second switches between a positive side of the first direct-current power supply and a ground, and the third switch connected between an interconnection point between the first and second switches and a negative side of the second direct-current power supply, thereby to selectively form a conduction path for electric charging/discharging to/from the one end of the actuator; and

a second switch circuit which comprises a serial circuit and a sixth switch, the serial circuit connecting fourth and fifth switches between the positive side of the first direct-current power supply and the ground, and the sixth switch connected between an interconnection point between the fourth and fifth switches and the negative side of the second direct-current power supply, thereby to selectively form a conduction path for electric charging/discharging to/from the other end of the actuator.

8. The apparatus of claim 1 , wherein

the drive circuit comprises:

first and second direct-current power supplies which are connected in series to each other and have an interconnection point grounded;

a third direct-current power supply with a negative side thereof grounded;

a first switch circuit which comprises a serial circuit and a third semiconductor device, the serial circuit connecting first and second semiconductor devices between a positive side of the first direct current power supply and a ground, the third semiconductor device connected between an interconnection point between the first and second semiconductor devices and a negative side of the second direct-current power supply, a back gate of the first semiconductor device connected to a positive side of the third direct-current power supply, and back gates of the second and third semiconductor devices connected to a negative side of the second direct-current power supply, thereby to selectively form a conduction path for electric charging/discharging to/from the one end of the actuator; and

a second switch circuit which comprises a serial circuit and a sixth semiconductor device, the serial circuit connecting fourth and fifth semiconductor devices between the positive side of the first direct-current power supply and the ground, the sixth semiconductor device connected between an interconnection point between the fourth and fifth semiconductor devices and the negative side of the second direct-current power supply, a back gate of the fourth semiconductor device connected to the positive side of the third direct-current power supply, and back gates of the fifth and sixth semiconductor devices connected to the negative side of the second direct-current power supply, thereby to selectively form a conduction path for electric charging/discharging to/from the other end of the actuator.