Head unit control circuit

Patent metadata

Field	Value
Publication number	US-10688784-B2
Application number	US-201616065908-A
Country	US
Kind code	B2
Filing date	Dec 22, 2016
Priority date	Dec 25, 2015
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

A head unit control circuit controls a head unit. The head unit includes: an ejector, a determination circuit, and an ejection limit circuit. The injector includes a displaceable piezoelectric element. The piezoelectric element is displaced by changing a drive signal potential. The determination circuit determines whether the piezoelectric element has a predetermined electrical storage capability. The ejection limit circuit stops the drive signal to limit the ejection of the liquid based on the determination. The head unit control circuit supplies an instruction signal, a first designation signal, and a second designation signal to the head unit. The instruction signal instructs the head unit to execute the determination. The determination circuit executes the determination during a period in which the first designation signal is set to a high level, the second designation signal is set to a low level, and the instruction signal is supplied.

First claim

The invention claimed is:

1. A head unit control circuit that controls a head unit, and is provided outside the head unit, the head unit including:
an ejecting section that includes a piezoelectric element, and can eject a liquid corresponding to displacement of the piezoelectric element, the piezoelectric element being displaced corresponding to a change in potential of a drive signal when the drive signal has been supplied to the piezoelectric element;
a determination circuit that performs a determination process that determines whether or not the piezoelectric element has a predetermined electrical storage capability based on a signal detected from the ejecting section, and outputs a signal that represents a result of the determination process; and
an ejection limit circuit that stops the supply of the drive signal to the piezoelectric element and limits the ejection of the liquid from the ejection section when the result of the determination process is negative,
the head unit control circuit supplying an instruction signal, a first designation signal, and a second designation signal to the head unit, the instruction signal instructing the head unit to execute the determination process,
the determination circuit executing the determination process during a determination period in which the first designation signal is set to a high level, the second designation signal is set to a low level, and the instruction signal is supplied.

2. The head unit control circuit as defined in claim 1 ,
the first designation signal designating whether or not to cause the ejecting section to eject the liquid when the result of the determination process is affirmative and the liquid can be ejected from the ejecting section, and
the second designation signal being set to the low level so that a first switch is turned ON when the result of the determination process is affirmative and the liquid can be ejected from the ejecting section, the first switch being provided between a first line and the piezoelectric element, the drive signal being supplied to the first line.

3. The head unit control circuit as defined in claim 2 ,
the head unit including a plurality of the ejecting sections, and
the first designation signal designating one of the plurality of the ejecting sections as a target for the determination process during a start-up period in which the second designation signal is set to a high level, the start-up period being included in a period until the determination period starts after power supply to the head unit has started.

4. The head unit control circuit as defined in claim 2 , further comprising:
a first terminal that outputs the instruction signal;
a second terminal that outputs the drive signal; and
a third terminal that is provided between the first terminal and the second terminal,
the third terminal being smaller in potential change width than the second terminal when the ejecting section ejects the liquid.

5. The head unit control circuit as defined in claim 1 ,
the head unit including a plurality of the ejecting sections, and
the first designation signal designating one of the plurality of the ejecting sections as a target for the determination process during a start-up period in which the second designation signal is set to a high level, the start-up period being included in a period until the determination period starts after power supply to the head unit has started.

6. The head unit control circuit as defined in claim 5 , further comprising:
a first terminal that outputs the instruction signal;
a second terminal that outputs the drive signal; and
a third terminal that is provided between the first terminal and the second terminal,
the third terminal being smaller in potential change width than the second terminal when the ejecting section ejects the liquid.

7. The head unit control circuit as defined in claim 1 ,
the ejection limit circuit including a first switch that is electrically connected between a first line and the piezoelectric element, the drive signal being supplied to the first line, and
when the result of the determination process is negative, the ejection limit circuit causing the first switch to be turned OFF when the first designation signal is set to a low level from the high level, and the second designation signal is set to a high level from the low level after the determination period has ended.

8. The head unit control circuit as defined in claim 7 , further comprising:
a second line; and
a second switch that is electrically connected between the piezoelectric element and the second line,
the second switch maintaining an ON state at least during the determination period, and
the determination circuit determining that the piezoelectric element has the predetermined electrical storage capability when a potential difference between a potential of the first line and a potential of the second line is equal to or smaller than a predetermined potential difference at a predetermined timing during the determination period.

9. The head unit control circuit as defined in claim 8 , further comprising:
a first terminal that outputs the instruction signal;
a second terminal that outputs the drive signal; and
a third terminal that is provided between the first terminal and the second terminal,
the third terminal being smaller in potential change width than the second terminal when the ejecting section ejects the liquid.

10. The head unit control circuit as defined in claim 7 , further comprising:
a first terminal that outputs the instruction signal;
a second terminal that outputs the drive signal; and
a third terminal that is provided between the first terminal and the second terminal,
the third terminal being smaller in potential change width than the second terminal when the ejecting section ejects the liquid.

11. The head unit control circuit as defined in claim 1 , further comprising:
a first terminal that outputs the instruction signal;
a second terminal that outputs the drive signal; and
a third terminal that is provided between the first terminal and the second terminal,
the third terminal being smaller in potential change width than the second terminal when the ejecting section ejects the liquid.

12. A head unit control circuit that controls a head unit, and is provided outside the head unit, the head unit including:
an ejecting section that includes a piezoelectric element, and can eject a liquid corresponding to displacement of the piezoelectric element, the piezoelectric element being displaced corresponding to a change in potential of a drive signal when the drive signal has been supplied to the piezoelectric element; and
a diagnosis circuit that performs a diagnosis process that diagnoses an electrical storage capability of the piezoelectric element based on a signal detected from the ejecting section, and outputs a signal that represents a result of the diagnosis process, and stops the supply of the drive signal to the piezoelectric element when the result of the diagnosis process is a predetermined result to limit the ejection of the liquid from the ejecting section,
the head unit control circuit supplying a diagnosis control signal, a first designation signal, and a second designation signal to the head unit,
the diagnosis circuit executing the diagnosis processs in response to the diagnosis control signal during a diagnosis period in which the first designation signal is set to a high level, and the second designation signal is set to a low level.

13. The head unit control circuit as defined in claim 12 ,
the diagnosis circuit including a first switch that is electrical

Assignees

• Seiko Epson Corp

Inventors

• Furukawa Ryota

Classifications

• B41J2/04571

  detecting viscosity · CPC title

• B41J2/04593

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

• B41J2/04551

  using several operating modes · CPC title

• B41J2/04596

  Non-ejecting pulses · CPC title

• B41J2/0451

  for detecting failure, e.g. clogging, malfunctioning actuator · CPC title