Drive device
A drive device includes a drive circuit to output a drive signal that is to be applied to an actuator of a liquid ejection head for ejecting liquid droplets. The drive signal includes an adjustment ejection waveform portion that includes a first portion having an expansion pulse that decreases pressure in a pressure chamber of the actuator and a second portion having a contraction pulse that increases pressure in the pressure chamber. The contraction pulse includes voltage increase changes that change the voltage applied to the actuator stepwise and a return pulse that is between a pair of voltage increase changes. The return pulse changes from a first voltage level that is less than a maximum voltage level of the contraction pulse to a second voltage level that is greater than a minimum voltage level of the expansion pulse.
1 . A drive device, comprising:
a drive circuit configured to output a drive signal waveform to be applied to an actuator of a liquid ejection head, wherein
the drive signal waveform includes an adjustment ejection waveform portion that causes liquid to be ejected once by a cycle of expansion and contraction and includes:
a first portion having an expansion pulse that decreases pressure in a pressure chamber of the actuator, and
a second portion having a contraction pulse that increases pressure in the pressure chamber, the contraction pulse including a plurality of voltage increase changes that change the voltage applied to the actuator stepwise and a return pulse that is between a pair of voltage increase changes in the plurality of voltage increase changes, the return pulse changing from a first voltage level that is less than a maximum voltage level of the contraction pulse to a second voltage level that is greater than a minimum voltage level of the expansion pulse.
2 . The drive device according to claim 1 , wherein the difference between the first voltage level and the second voltage level is equal to the magnitude of a voltage increase change in the plurality of voltage increase changes.
3 . The drive device according to claim 1 , wherein the difference between the first voltage level and the second voltage level is equal to one-half the magnitude of the expansion pulse.
4 . The drive device according to claim 1 , wherein the return pulse changes in discrete steps from the first voltage level to the second voltage level.
5 . The drive device according to claim 4 , wherein the return pulse changes in discrete steps from the second voltage level to first voltage level.
6 . The drive device according to claim 5 , wherein magnitudes of each of the discrete steps are equal.
7 . The drive device according to claim 1 , wherein the expansion pulse changes voltage in discrete steps from a reference voltage level to the minimum voltage level.
8 . The drive device according to claim 7 , wherein the expansion pulse changes voltage in discrete steps from the minimum voltage level to the reference voltage level.
9 . The drive device according to claim 1 , wherein
the drive signal waveform is a multi-drop waveform having a plurality of drop waveforms in sequence, and
the adjustment ejection waveform is part of at least one of the drop waveforms of the plurality of drop waveforms.
10 . The drive device according to claim 9 , wherein the adjustment ejection waveform is part of the first drop waveform in the sequence of the plurality of drop waveforms.
11 . The drive device according to claim 10 , wherein the second drop waveform in the sequence of the plurality of drop waveforms is a reference ejection waveform including an expansion pulse that decreases pressure in the pressure chamber and a contraction pulse that increases the pressure in the pressure chamber in discrete steps.
12 . The drive device according to claim 1 , wherein the drive circuit is configured to control an ejection volume by adjusting a pulse width of the return pulse.
13 . The drive device according to claim 1 , wherein the second voltage level is a ground potential.
14 . A liquid ejection head, comprising:
an actuator that expands and contracts a pressure chamber to eject a liquid from a nozzle associated with the pressure chamber; and
a drive circuit configured to output a drive signal waveform to be applied to the actuator, wherein
the drive signal waveform includes an adjustment ejection waveform portion that causes liquid to be ejected once by a cycle of expansion and contraction and includes:
a first portion having an expansion pulse that decreases pressure in a pressure chamber of the actuator, and
a second portion having a contraction pulse that increases pressure in the pressure chamber, the contraction pulse including a plurality of voltage increase changes that change the voltage applied to the actuator stepwise and a return pulse that is between a pair of voltage increase changes in the plurality of voltage increase changes, the return pulse changing from a first voltage level that is less than a maximum voltage level of the contraction pulse to a second voltage level that is greater than a minimum voltage level of the expansion pulse.
15 . The liquid ejection head according to claim 14 , wherein the difference between the first voltage level and the second voltage level is equal to the magnitude of a voltage increase change in the plurality of voltage increase changes.
16 . The liquid ejection head according to claim 14 , wherein
the drive signal waveform is a multi-drop waveform having a plurality of drop waveforms in sequence, and
the adjustment ejection waveform is part of at least one of the drop waveforms of the plurality of drop waveforms.
17 . The liquid ejection head according to claim 14 , wherein the drive circuit is configured to control an ejection volume by adjusting a pulse width of the return pulse.
18 . A printer, comprising:
an inkjet head; and
a sheet conveying mechanism configured to position a sheet relative to the inkjet head, wherein
the inkjet head includes:
an actuator that expands and contracts a pressure chamber to eject a liquid from a nozzle associated with the pressure chamber; and
a drive circuit configured to output a drive signal waveform to be applied to the actuator, wherein
the drive signal waveform includes an adjustment ejection waveform portion that causes liquid to be ejected once by a cycle of expansion and contraction and includes:
a first portion having an expansion pulse that decreases pressure in a pressure chamber of the actuator, and
a second portion having a contraction pulse that increases pressure in the pressure chamber, the contraction pulse including a plurality of voltage increase changes that change the voltage applied to the actuator stepwise and a return pulse that is between a pair of voltage increase changes in the plurality of voltage increase changes, the return pulse changing from a first voltage level that is less than a maximum voltage level of the contraction pulse to a second voltage level that is greater than a minimum voltage level of the expansion pulse.
19 . The printer according to claim 18 , wherein the difference between the first voltage level and the second voltage level is equal to the magnitude of a voltage increase change in the plurality of voltage increase changes.
20 . The printer according to claim 18 , wherein
the drive signal waveform is a multi-drop waveform having a plurality of drop waveforms in sequence, and
the adjustment ejection waveform is part of at least one of the drop waveforms of the plurality of drop waveforms.