Liquid discharge apparatus and print head

Patent metadata

Field	Value
Publication number	US-10507649-B2
Application number	US-201816140994-A
Country	US
Kind code	B2
Filing date	Sep 25, 2018
Priority date	Sep 27, 2017
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

A liquid discharge apparatus includes a piezoelectric element that has a first electrode, a piezoelectric body, and a second electrode, a first switch that is capable of switching whether to supply a drive signal for driving the piezoelectric element to the first electrode, and a second switch that is arranged electrically in parallel with the piezoelectric element and is capable of switching whether to electrically connect the first electrode and the second electrode to each other.

First claim

What is claimed is:

1. A liquid discharge apparatus comprising:
a piezoelectric element that has a first electrode, a piezoelectric body, and a second electrode;
a first switch that is capable of switching whether to supply a drive signal for driving the piezoelectric element to the first electrode; and
a second switch that is arranged electrically in parallel with the piezoelectric element and is capable of switching whether to electrically connect the first electrode and the second electrode to each other.

2. The liquid discharge apparatus according to claim 1 ,
wherein the piezoelectric element is formed as a polycrystal body and is subject to poling.

3. The liquid discharge apparatus according to claim 1 ,
wherein the second switch switches whether to electrically connect the first electrode and the second electrode to each other so as not to change a magnitude relation between a potential of the first electrode and a potential of the second electrode.

4. The liquid discharge apparatus according to claim 1 ,
wherein a potential of the second electrode is set to be a first potential that is higher than a ground potential.

5. The liquid discharge apparatus according to claim 1 ,
wherein the second switch electrically connects the first electrode and the second electrode to each other when a potential of the first electrode is lower than a potential of the second electrode.

6. The liquid discharge apparatus according to claim 5 ,
wherein the second switch electrically connects the first electrode and the second electrode to each other when a state in which the potential of the first electrode is lower than the potential of the second electrode lasts for a first time length.

7. The liquid discharge apparatus according to claim 6 , further including a delay unit that delays a first signal indicating whether the potential of the first electrode is lower than the potential of the second electrode at first timing to second timing the first time length after the first timing,
wherein the second switch electrically connects the first electrode and the second electrode to each other when both of the first signal delayed to the second timing and a second signal indicating whether the potential of the first electrode is lower than the potential of the second electrode at the second timing indicate that the potential of the first electrode is lower than the potential of the second electrode.

8. The liquid discharge apparatus according to claim 5 ,
wherein the second switch electrically connects the first electrode and the second electrode to each other when the potential of the first electrode is set to be lower than a second potential that is set to be lower than the potential of the second electrode.

9. The liquid discharge apparatus according to claim 1 , further including a comparison unit that compares a potential of the first electrode and a potential of the second electrode,
wherein the second switch switches whether to electrically connect the first electrode and the second electrode to each other in accordance with a comparison result by the comparison unit.

10. The liquid discharge apparatus according to claim 1 ,
wherein in a first period,
a waveform for driving the piezoelectric element is set to the drive signal,
the first switch is set to be in a state of supplying the drive signal to the first electrode, and
the second switch is set to be in a state of electrically disconnecting the first electrode and the second electrode from each other, and

in a second period other than the first period,
the first switch is set to be in a state of supplying no drive signal to the first electrode, and
the second switch is set to be in a state of electrically connecting the first electrode and the second electrode to each other.

11. The liquid discharge apparatus according to claim 1 ,
wherein discharge portions that include piezoelectric elements using thin-film piezoelectric bodies and are capable of discharging liquid are aligned with a density of equal to or higher than 300 dpi.

12. A print head comprising:
a piezoelectric element that has a first electrode, a piezoelectric body, and a second electrode;
a first switch that is capable of switching whether to supply a drive signal for driving the piezoelectric element to the first electrode; and
a second switch that is arranged electrically in parallel with the piezoelectric element and is capable of switching whether to electrically connect the first electrode and the second electrode to each other.

13. The print head according to claim 12 ,
wherein the piezoelectric element is formed as a polycrystal body and is subject to poling.

14. The print head according to claim 12 ,
wherein the second switch switches whether to electrically connect the first electrode and the second electrode to each other so as not to change a magnitude relation between a potential of the first electrode and a potential of the second electrode.

15. The print head according to claim 12 ,
wherein a potential of the second electrode is set to be a first potential that is higher than a ground potential.

16. The print head according to claim 12 ,
wherein the second switch electrically connects the first electrode and the second electrode to each other when a potential of the first electrode is lower than a potential of the second electrode.

17. The print head according to claim 12 , further including a comparison unit that compares a potential of the first electrode and a potential of the second electrode,
wherein the second switch switches whether to electrically connect the first electrode and the second electrode to each other in accordance with a comparison result by the comparison unit.

Assignees

• Seiko Epson Corp

Inventors

• Tada Keiichi

Classifications

• B41J2/04541 Primary

  Specific driving circuit · CPC title

• B41J2/04573

  Timing; Delays · CPC title

• B41J2/0455

  Details of switching sections of circuit, e.g. transistors · CPC title

• B41J2/04593

  Dot-size modulation by changing the size of the drop · CPC title

• B41J2/04581

  controlling heads based on piezoelectric elements · CPC title