Liquid surface sensor and liquid surface detection method

Patent metadata

Field	Value
Publication number	US-10656003-B2
Application number	US-201816203908-A
Country	US
Kind code	B2
Filing date	Nov 29, 2018
Priority date	Nov 30, 2017
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

A liquid surface sensor includes a hollow member having a first opening end and a second opening end, and a sensor unit provided so as to close the first opening end of the hollow member. The sensor unit includes a vibration plate, and a piezoelectric element which is provided on the vibration plate and is formed by laminating a first electrode film, a piezoelectric film, and a second electrode film in a thickness direction of the vibration plate.

First claim

What is claimed is:

1. A printer comprising:
an ink tank configured to store an ink therein, the ink being supplied from outside of the ink tank into the tank;
a carriage having a printing member, the ink tank being provided on the carriage, the printing member being configured to eject the ink onto a medium;
a carriage drive mechanism configured to move the carriage;
an ink surface detector, the ink surface detector being provided inside the ink tank, the ink surface detector being configured with:
a hollow member that has a first opening end and a second opening end opposite to each other, at least the second opening end being immersed in the ink; and
a piezoelectric sensor that is provided so as to close the first opening end of the hollow member, wherein the piezoelectric sensor includes a vibration plate, and a piezoelectric element that is provided on the vibration plate, and the piezoelectric element is formed by laminating a first electrode film, a piezoelectric film, and a second electrode film in order in a thickness direction of the vibration plate; and

a controller, the controller being configured to:
cause the piezoelectric sensor to vibrate the vibration plate and detect a resonant frequency;
cause the piezoelectric sensor to propagate an acoustic wave toward the ink and receive a reflected acoustic wave that is generated by reflecting the acoustic wave of the ink;
calculate a first position of an ink surface of the ink in the ink tank in response to the resonate frequency;
calculate a second positon of the ink surface in response to the acoustic wave and the reflected acoustic wave; and
determine a corrected position of the ink surface based on the first and second positons,

wherein the controller is configured to adjust a positon of the ink surface to a predetermined positon in response to the corrected positon by adjusting an ink supply amount of the ink that is supplied into the ink tank.

2. The printer according to claim 1 ,
wherein a total film thickness of the vibration plate and the piezoelectric element is equal to or lower than 5 μm.

3. A liquid surface detection method for a printer, the printer being configured with;
an ink tank configured to store an ink therein, the ink being supplied from Outside of the ink into the ink tank;
a carriage having a printing member, the ink tank being provided on the carriage, the printing member being configured to eject the ink onto a medium;
a carriage drive mechanism configured to move the carriage; and
an ink surface detector, the ink surface detector being provided inside the ink tank, the ink surface detector being configured with:
a hollow member that has a first opening end and a second opening end opposite to each other, at least the second opening end being immersed in the ink; and
a piezoelectric sensor that is provided so as to close the first opening end of the hollow member, wherein the piezoelectric sensor includes a vibration plate, and a piezoelectric element that is provided on the vibration plate, and the piezoelectric element is formed by laminating a first electrode film, a piezoelectric film, and a second electrode film in order in a thickness direction of the vibration plate, the method for causing a controller to execute a process, the method comprising executing on the controlling the steps of:

cause the piezoelectric sensor to vibrate the vibration plate and detect a resonant frequency;
cause the piezoelectric sensor to propagate an acoustic wave toward the ink and receive a reflected acoustic wave that is generated by reflecting the acoustic wave of the ink;
calculate a first position of an ink surface of the ink in the ink tank in response to the resonate frequency;
calculate a second positon of the ink surface in response to the acoustic wave and the reflected acoustic wave;
determine a corrected position of the ink surface based on the first and second positons; and
adjusting a position of the ink surface to a predetermined position in response to the corrected positon by adjusting an ink supply amount of the ink that is supplied into the ink tank.

Assignees

• Seiko Epson Corp

Inventors

• Kojima Chikara

Classifications

• G01F23/2966 Primary

  making use of acoustical resonance or standing waves · CPC title

• B41J2/17566

  Ink level or ink residue control · CPC title

• G01F23/2962

  Measuring transit time of reflected waves · CPC title

• B41J2002/17583

  using vibration or ultra-sons for ink level indication · CPC title

• G01F23/2968

  Transducers specially adapted for acoustic level indicators · CPC title