Inkjet head driving circuit that avoids unwanted high-frequency actuator vibration
According to one embodiment, an inkjet head driving circuit includes a waveform pattern generation unit configured to generate a waveform pattern based on input data and a driving waveform generation unit configured to generate a driving waveform for driving an actuator of an inkjet head based on the generated waveform pattern. The driving waveform generation unit includes a power source configured to supply a driving voltage for the actuator, a plurality of switch elements for connecting the power source to the actuator, and a driving waveform output unit that outputs the driving waveform to the actuator by switching of the plurality of switch elements based on the waveform pattern. The waveform pattern changes the number of switch elements that are turned on in a section of the driving waveform within one cycle of the driving waveform for causing the actuator to eject an ink droplet.
1 . An inkjet head driving circuit, comprising:
a waveform pattern generation circuit configured to generate a waveform pattern based on input data; and
a driving waveform generation circuit configured to generate a driving waveform for driving an actuator of an inkjet head based on the generated waveform pattern, wherein
the driving waveform generation circuit includes:
a power source configured to supply a driving voltage for the actuator, and
a driving waveform output circuit including a plurality of switch elements for connecting the power source to the actuator, the driving waveform output circuit being configured to output the driving waveform to the actuator by switching of the plurality of switch elements based on the waveform pattern,
the waveform pattern changes the number of switch elements among the plurality of switch elements that are turned on in at least one section of the driving waveform among a plurality of sections within one cycle of the driving waveform for causing the actuator to eject an ink droplet,
the power source comprises a first power source that supplies a first voltage and a second power source that supplies a second voltage,
the plurality of switches includes:
a first pair of switch elements connected in parallel with the actuator,
a second pair of switch elements connected in parallel between the actuator and the first power source, and
a third pair of switch elements connected in parallel between the actuator and the second power source,
in the first pair of switch elements, ON resistance of one switch element is different from ON resistance of the other switch element,
in the second pair of switch elements, ON resistance of one switch element is different from ON resistance of the other switch element, and
in the third pair of switch elements, ON resistance of one switch element is different from ON resistance of the other switch element.
2 . The inkjet head driving circuit according to claim 1 , wherein the ON resistance of one switch element in the first pair of switch elements, the ON resistance of one switch element in the second pair of switch elements, and the ON resistance of one switch element of the third pair of switch elements are equal to each other.
3 . The inkjet head driving circuit according to claim 2 , wherein the ON resistance of the other switch element in the first pair of switch elements, the ON resistance of the other switch element in the second pair of switch elements, and the ON resistance of the other switch element of the third pair of switch elements are equal to each other.
4 . The inkjet head driving circuit according to claim 1 , wherein the waveform pattern generation circuit includes a selection data generation circuit that generates selection data for selecting a switch element to be turned on for one cycle of the waveform pattern.
5 . The inkjet head driving circuit according to claim 1 , wherein the waveform pattern generated by the waveform pattern generation circuit includes selection data for selecting a switch element to be turned on.
6 . An inkjet head driving circuit, comprising:
a logical unit circuit configured to generate control signals for driving a plurality of actuators of an inkjet head for ejecting liquid; and
an analog unit circuit configured to receive the control signals from the logical unit circuit and to output a drive waveform for an actuator of the inkjet head corresponding to the control signals, wherein
the analog unit circuit includes a plurality of switches including:
a first switch connected between a first terminal of the actuator and a second terminal of the actuator;
a second switch connected in parallel with the first switch between the first terminal of the actuator and the second terminal of the actuator;
a third switch connected between the first terminal of the actuator and a first power supply line;
a fourth switch connected in parallel with the third switch between the first terminal of the actuator and the first power supply line;
a fifth switch connected between the first terminal of the actuator and a second power supply line; and
a sixth switch connected in parallel with the fifth switch between the first terminal of the actuator and the second power supply line, wherein
the second terminal of the actuator is connected to a third power supply line,
the control signals from the logical unit circuit change the number of switches among the plurality of switches that are turned on in at least one section of the driving waveform among a plurality of sections within one cycle of the driving waveform for causing the actuator to eject an ink droplet,
ON resistance of first switch is different from ON resistance of the second switch,
ON resistance of third switch is different from ON resistance of the fourth switch,
ON resistance of fifth switch is different from ON resistance of the sixth switch,
the first power supply line is connected to a first potential,
the third power supply line is connected to a second potential, and
the second power supply line is connected to a third potential that is between the first and second potentials.
7 . The inkjet head driving circuit according to claim 6 , wherein the ON resistance of the first, third, and fifth switches are equal to each other.
8 . The inkjet head driving circuit according to claim 7 , wherein the ON resistance of the second, fourth, and sixth switches are equal to each other.
9 . The inkjet head driving circuit according to claim 7 , wherein
the logical unit circuit includes a selection data generation unit circuit that generates selection data for selecting switches among the plurality of switches to be turned on during one cycle of the drive waveform.
10 . The inkjet head driving circuit according to claim 6 , wherein the analog unit circuit further includes:
a level shifter configured to receive the control signals from the logical unit circuit; and
a pre-buffer configured to receive the control signals from the level shifter.
11 . The inkjet head driving circuit according to claim 6 , wherein the second potential is a ground potential.
12 . An inkjet printer, comprising:
an inkjet head configured to eject liquid, the inkjet head including:
an actuator group with a plurality actuators; and
a head driving circuit configured to drive the plurality of actuators to eject liquid from pressure chambers associated with the plurality of actuators, wherein the head driving circuit includes:
a logical unit circuit configured to generate control signals for driving the plurality of actuators for ejecting liquid; and
an analog unit circuit configured to receive the control signals from the logical unit circuit and to output a drive waveform for an actuator corresponding to the control signals,
the analog unit circuit includes a plurality of switches including:
a first switch connected between a first terminal of the actuator and a second terminal of the actuator;
a second switch connected in parallel with the first switch between the first terminal of the actuator and the second terminal of the actuator;
a third switch connected between the first terminal of the actuator and a first power supply line;
a fourth switch connected in parallel with the third switch between the first terminal of the actuator and the first power supply line;
a fifth switch connected between the first terminal of the actuator and a second power supply line; and
a sixth switch connected in parallel with the fifth switch between the first terminal of the actuator and the second power supply line, wherein
the second terminal of the actuator is connected to a third power supply line, and
the control signals from the logical unit circuit change the number of switches among the plurality of switches that are turned on in at least one section of the driving waveform among a plurality of sections within one cycle of the driving waveform for causing the actuator to eject an ink droplet,
ON resistance of first switch is different from ON resistance of the second switch,
ON resistance of third switch is different from ON resistance of the fourth switch,
ON resistance of fifth switch is different from ON resistance of the sixth switch,
the first power supply line is connected to a first potential,
the third power supply line is connected to a second potential, and
the second power supply line is connected to a third potential that is between the first and second potentials.
13 . The inkjet printer according to claim 12 , wherein the ON resistance of the first, third, and fifth switches are equal to each other.
14 . The inkjet printer according to claim 13 , wherein the ON resistance of the second, fourth, and sixth switches are equal to each other.
15 . The inkjet printer according to claim 12 , wherein
the logical unit circuit includes a selection data generation unit circuit that generates selection data for selecting switches among the plurality of switches to be turned on during one cycle of the drive waveform.