Method for detecting an operating status of an inkjet nozzle

Patent metadata

Field	Value
Publication number	US-10144215-B2
Application number	US-201715643212-A
Country	US
Kind code	B2
Filing date	Jul 6, 2017
Priority date	Jan 13, 2015
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

An inkjet print head includes an ejection unit having a liquid chamber for holding an amount of liquid, a electromechanical transducer operatively coupled to the liquid chamber for generating a pressure wave in the amount of liquid and a nozzle in fluid communication with the liquid chamber for enabling a droplet of the amount of liquid to be ejected through the nozzle. A method for detecting an operating state of the ejection unit includes the consecutive steps of actuating the electromechanical transducer to generate a pressure wave in the liquid; actuating the electromechanical transducer to suppress a residual pressure wave in the liquid; sensing an amplitude of the residual pressure wave in the liquid; and based on the result of the sensing step determining that the ejection unit is (i) in an operative state if the amplitude of the residual pressure wave is below a threshold or (ii) in a malfunctioning state if the amplitude of the residual pressure wave is above the threshold.

First claim

The invention claimed is:

1. A method for detecting an operating state of an ejection unit of an inkjet print head, the ejection unit comprising a liquid chamber for holding an amount of liquid, a electromechanical transducer operatively coupled to the liquid chamber for generating a pressure wave in the amount of liquid and a nozzle in fluid communication with the liquid chamber for enabling a droplet of the amount of liquid to be ejected through the nozzle, the method consecutively comprising
a. actuating the electromechanical transducer to generate a pressure wave in the liquid;
b. actuating the electromechanical transducer with an actuation pulse adapted to the pressure wave generated in the liquid in an operative ejection unit to suppress a residual pressure wave in the liquid;
c. sensing an amplitude of the suppressed residual pressure wave in the liquid;
d. based on the result of step c. determining that the ejection unit is
i. in an operative state if the amplitude of the suppressed residual pressure wave is below a threshold;
ii. in a malfunctioning state if the amplitude of the suppressed residual pressure wave is above the threshold.

2. The method according to claim 1 , wherein the electromechanical transducer is a piezo-actuator.

3. The method according to claim 1 , wherein step a. includes ejecting a droplet through the nozzle.

4. The method according to claim 1 , wherein step c. comprises sensing the residual pressure wave for a predetermined period of time and deriving the amplitude from the sensed pressure wave.

5. The method according to claim 1 , wherein if it is determined that the ejection unit is in a malfunctioning state, the method further comprises the consecutive steps
e. actuating the electromechanical transducer to generate a non-ejecting pressure wave in the liquid, thereby not ejecting a droplet;
f. sensing the residual pressure wave; and
g. analyzing the sensed residual pressure wave in order to determine a cause for the malfunctioning state.

Assignees

• Oce Tech Bv

Inventors

• Mihailovic Marko
• Hummel Tjerk E C
• Simons Johannes M M
• Veenstra Hylke
• Venner Cornelis W M
• Khalate Amol A

Classifications

• B41J2002/14354

  Sensor in each pressure chamber · CPC title

• B41J2/04581

  controlling heads based on piezoelectric elements · CPC title

• B41J2/04596

  Non-ejecting pulses · CPC title

• B41J2/0451 Primary

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

• B41J2/04586

  controlling heads of a type not covered by groups B41J2/04575 - B41J2/04585, or of an undefined type · CPC title