Head drive unit and inkjet printer

Patent metadata

Field	Value
Publication number	US-9289981-B2
Application number	US-201314403447-A
Country	US
Kind code	B2
Filing date	May 24, 2013
Priority date	May 24, 2012
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

An object is to provide a head drive unit that prevents an increase in viscosity of inks in nozzles even when a head is present outside an image forming region and also provide an inkjet printer, and the head drive unit includes: a drive signal output device 31 that outputs either a discharge signal or a meniscus oscillation signal to each head; a cycle generator 326 that generates a cyclic oscillation timing signal for the meniscus oscillation signal; an input interruption detector 324 that detects that input of a print timing signal is interrupted; and a drive signal selector 32 that selects the meniscus oscillation signal as a drive signal output from the drive signal output device and continuously applies the meniscus oscillation signal to all nozzles of each head in synchronization with an oscillation timing signal when interruption of the input of the print timing signal is detected.

First claim

The invention claimed is:

1. A head drive unit comprising:
an inkjet head driven based on a drive signal; and
a head drive apparatus that outputs a discharge signal to the inkjet head based on image data and a print timing signal that are input from an external apparatus, and discharges a droplet from a nozzle to form an image on a recording medium,
wherein the head drive apparatus comprises:
a drive signal output unit for outputting either the discharge signal used for discharging a droplet from the nozzle to form an image or a flushing signal used for forcedly discharging a droplet from the nozzle without forming an image as a drive signal to the inkjet head, the drive signal output unit continuously applying the flushing signal to all nozzles of the inkjet head in synchronization with a cyclic flushing timing signal when the input interruption detection unit detects that input of the print timing signal has been interrupted;
a cycle generation unit for generating the cyclic flushing timing signal for the flushing signal;
an input interruption detection unit for detecting that no input is made and input of the print timing signal is interrupted even though a preset time has elapsed by monitoring input of the print timing signal; and
a drive signal selection unit for selecting the flushing signal as the drive signal output from the drive signal output unit.

2. The head drive unit according to claim 1 , wherein the drive signal selection unit has a time measurement unit for measuring a duration time of output of the flushing signal, and wherein the drive signal output unit stops the flushing signal and switches the drive signal to the discharge signal when the flushing signal is selected as the drive signal and then the time measurement unit measures elapse of a preset time.

3. The head drive unit according to claim 1 , wherein the drive signal selection unit has a number-of-time measurement unit for measuring the number of times of outputting the flushing signal, and wherein the drive signal output unit stops the flushing signal and switches the drive signal to the discharge signal when the flushing signal is selected as the drive signal and then the number-of-time measurement unit measures a present number of times of outputting the selected signal.

4. An inkjet printer comprising:
a head drive unit according to claim 1 ;
a recording medium carrying apparatus for carrying the recording medium in a sub-scanning direction;
a head moving apparatus for moving the inkjet head in a main scanning direction crossing a carrying direction of the recording medium;
a positional information detecting apparatus for detecting positional information of the inkjet head relative to the recording medium; and
a print control apparatus that continuously outputs the image data and the print timing signal to the head drive apparatus based on the positional information detected by the positional information detecting apparatus only when the inkjet head is present in an image forming region for the recording medium.

5. A head drive unit comprising:
an inkjet head driven based on a drive signal; and
a head drive apparatus that outputs a discharge signal to the inkjet head based on image data and a print timing signal that are input from an external apparatus, and discharges a droplet from a nozzle to form an image on a recording medium,
wherein the head drive apparatus comprises:
a drive signal output unit for outputting either the discharge signal used for discharging a droplet from the nozzle to form an image or a meniscus oscillation signal for an oscillating liquid surface at a tip of the nozzle without discharging a droplet from the nozzle or a flushing signal used for forcedly discharging a droplet from the nozzle without forming an image to the inkjet head;
a cycle generation unit for generating at least either a cyclic oscillation timing signal for the meniscus oscillation signal or a cyclic flushing timing signal for the flushing signal;
an input interruption detection unit for detecting that no input is made and input of the print timing signal is interrupted even though a preset time has elapsed by monitoring input of the print timing signal; and
a drive signal selection unit for selecting the meniscus oscillation signal or the flushing signal as the drive signal output from the drive signal output unit when the input interruption detection unit detects that input of the print timing signal has been interrupted; and

wherein the drive signal output unit continuously applies the meniscus oscillation signal to all nozzles of the inkjet head in synchronization with the cyclic oscillation timing signal when the drive signal selection unit selects the meniscus oscillation signal, and continuously applies the flushing signal to all nozzles of the inkjet head in synchronization with the cyclic flushing timing signal when the drive signal selection unit selects the flushing signal.

6. An inkjet printer comprising:
a head drive unit according to claim 5 ;
a recording medium carrying apparatus for carrying the recording medium in a sub-scanning direction;
a head moving apparatus for moving the inkjet head in a main scanning direction crossing a carrying direction of the recording medium;
a positional information detecting apparatus for detecting positional information of the inkjet head relative to the recording medium; and
a print control apparatus that continuously outputs the image data and the print timing signal to the head drive apparatus based on the positional information detected by the positional information detecting apparatus only when the inkjet head is present in an image forming region for the recording medium.

7. The head drive unit according to claim 6 , wherein the drive signal selection unit has a timing measurement unit for measuring a duration time of output of the meniscus oscillation signal, and wherein the drive signal output unit stops the meniscus oscillation signal and switches the drive signal to the discharge signal when the meniscus oscillation signal is selected as the drive signal and then the time measurement unit measures elapse of a preset time.

8. The head drive unit according to claim 5 , wherein the drive signal selection unit has a number-of-time measurement unit for measuring the number of times of outputting the meniscus oscillation signal, and wherein the drive signal output unit stops the meniscus oscillation signal and switches the drive signal to the discharge signal when the meniscus oscillation signal is selected as the drive signal and then the number-of-time measurement unit measures a preset number of times of outputting the selected signal.

9. The head drive unit according to claim 5 , wherein the drive signal selection unit has a time measurement unit for measuring a duration time of output of the flushing signal, and wherein the drive signal output unit stops the flushing signal and switches the drive signal to the discharge signal when the flushing signal is selected as the drive signal and then the time measurement unit measures elapse of a preset time.

10. The head drive unit according to claim 5 , wherein the drive signal selection unit has a number-of-time measurement unit for measuring the number of times of outputting the flushing signal, and wherein the drive signal output unit stops the flushing signal and switches the drive signal to the discharge signal when the flushing signal is selected as the drive signal and then the number-of-time measurement unit measures a present number of times of outputting the selected signal.

Assignees

• Konica Minolta Inc

Inventors

• Komada Naoya
• Tsubotani Shingo

Classifications

• B41J2/0458

  controlling heads based on heating elements forming bubbles · CPC title

• B41J2/04581

  controlling heads based on piezoelectric elements · CPC title

• B41J2/04573 Primary

  Timing; Delays · CPC title

• B41J2/01

  Ink jet · CPC title

• B41J2/04596

  Non-ejecting pulses · CPC title