Piezoelectric dispenser and method of calibrating stroke of the same

Patent metadata

Field	Value
Publication number	US-2016136661-A1
Application number	US-201514945295-A
Country	US
Kind code	A1
Filing date	Nov 18, 2015
Priority date	Nov 18, 2014
Publication date	May 19, 2016
Grant date	—

Abstract

A piezoelectric dispenser having a uniform dispensing quality of a viscous liquid by calibrating an operation stroke of a valve rod discharging a viscous liquid (vertical operation displacement of the valve rod) by setting the operation stroke of the valve rod to an initial value during use, and a method of calibrating the operation stroke of the piezoelectric dispenser. Accordingly, a uniform dispensing accuracy of viscous liquid may be maintained, and degradation of the dispensing quality of a viscous liquid due to abrasion of components may be reduced.

First claim

What is claimed is:

1 . A liquid dispenser comprising:
a valve assembly comprising a nozzle and a valve rod with a tip facing the nozzle, the valve rod configured to move along a first axis; at least one piezoelectric actuator configured to expand and shrink along a second axis in response to a voltage signal applied to the at least one piezoelectric actuator, the second axis being identical to or different from the first axis; a lever configured to move pivotally about a pivotal axis thereof and operably connected to the at least one piezoelectric actuator such that the lever pivotally moves as the at least one piezoelectric actuator expands and shrinks along the second axis; wherein the valve rod and the lever are operably connected such that, as the lever pivotally moves, the valve rod moves along the first axis and the tip reciprocates between a first position and a second position for dispensing liquid through the nozzle, wherein the second position changes over use of the liquid dispenser such that a stroke of the tip between the first position and the second position becomes longer or shorter; a lever-position detector connected to the lever and configured to detect the lever's position that is indicative of the tip's position; and at least one processor configured:
to process information from the lever-position detector to determine if the first position needs to be adjusted, and
upon determining that the first position needs to be adjusted, to generate a control signal for changing the voltage signal applied to the at least one piezoelectric actuator to adjust a level of expansion and shrinkage thereof along the second axis, which causes to adjust pivotal movement of the lever, which to further change the first position.

2 . The liquid dispenser of claim 1 , wherein the at least one processor is configured to determine if the first position needs to be adjusted by computing a distance of the stroke and then comparing the distance to the reference value.

3 . The liquid dispenser of claim 2 , wherein the at least one processor is configured to determine that the first position needs to be adjusted when the stroke has become longer than the reference value.

4 . The liquid dispenser of claim 1 , wherein the tip contacts the nozzle at the second position, wherein the stroke of the tip becomes longer over use of the liquid dispenser as a valve seat of the nozzle wears out by repeated impacts of the tip.

5 . The liquid dispenser of claim 1 , wherein for determining if the first position needs to be adjusted, the at least one processor is configured to determine if the stroke of the tip has become longer than a reference value based on information from the lever-position detector,
wherein the at least one processor is configured to determine that the first position needs to be adjusted when the stroke has become longer than the reference value, wherein the change of the first position is to make the stroke shorter than the reference value.

6 . The liquid dispenser of claim 5 , wherein the at least one processor is configured to determine if the stroke of the tip has become longer than the reference value by computing a distance of the stroke and then comparing the distance to the reference value.

7 . The liquid dispenser of claim 1 , wherein the at least one processor is configured to determine if the first position needs to be adjusted by computing the second position of the tip based on the information from the lever-position detector and then comparing the second position of the tip to a reference position.

8 . The liquid dispenser of claim 1 , wherein the voltage signal is configured to operate the at least one piezoelectric actuator such that the tip of the valve rod would move to a third position beyond the second position if the nozzle does not stop the valve rod's movement,
wherein an over-stroke defined by a distance between the second position and the third position becomes shorter than a reference distance when the stroke of the tip becomes longer than a reference value, wherein the at least one processor is configured to generate the control signal which is to change the third position such that the over-stroke is greater than the reference distance.

9 . The liquid dispenser of claim 1 , wherein the lever-position detector is a displacement sensor configured to sense the lever's position indicative of the tip's position relative to the first position or the second position and further configured to provide the information indicative of the lever's position to the at least one processor.

10 . The liquid dispenser of claim 1 , wherein the at least one piezoelectric actuator comprises a first piezoelectric actuator and a second piezoelectric actuator,
wherein the first piezoelectric actuator is configured to expand and the second piezoelectric actuator is configured to shrink to place the tip of the valve rod to the first position, wherein when the stroke of the tip becomes longer than a reference value, the at least one processor is configured to generate the control signal to reduce the amount of the expansion of the first piezoelectric actuator and the amount of the shrinkage of the second piezoelectric actuator for changing the first position of the tip of the valve rod.

11 . A method of dispensing liquid, the method comprising:
providing the liquid dispenser of claim 1 ; applying a voltage signal to the at least one piezoelectric actuator for its expansion and shrinkage along the second axis, which causes pivotal movement of the lever, which then to cause movement of the valve rod along the first axis such that the valve assembly dispenses liquid through the nozzle as the tip reciprocates between the first position and the second position at which the tip contacts the nozzle; detecting the lever's position that is indicative of the tip's position; processing information from the lever-position detector to determine if the first position needs to be adjusted; and upon determining that the first position needs to be adjusted, generating a control signal for changing the voltage signal applied to the at least one piezoelectric actuator to adjust a level of expansion and shrinkage thereof along the second axis, which causes to adjust pivotal movement of the lever, which to further change the first position.

12 . The method of claim 11 , wherein determining if the first position needs to be adjusted comprises computing a distance of the stroke and then comparing the distance to the reference value.

13 . The method of claim 12 , wherein it is determined that the first position needs to be adjusted when the stroke has become longer than the reference value.

14 . The method of claim 11 , wherein the tip contacts the nozzle at the second position, wherein the stroke of the tip becomes longer over use of the liquid dispenser as a valve seat of the nozzle wears out by repeated impacts of the tip.

15 . The method of claim 11 , wherein determining if the first position needs to be adjusted comprises determining if the stroke of the tip has become longer than a reference value based on information from the lever-position detector,
wherein it is determined that the first position needs to be adjusted when the stroke has become longer than the reference value, wherein the change of the first position is to make the stroke shorter than the reference value.

16 . The method of claim 15 , wherein determining if the stroke of the tip has become longer than the reference value comprises computing a distance of the stroke and then comparing the distance

Assignees

• Protec Co Ltd

Inventors

• Hong Seung Min
• Lee Hansung

Classifications

• B05B17/0607

  generated by electrical means, e.g. piezoelectric transducers · CPC title

• B05B1/3013 Primary

  Lift valves (B05B1/3033 takes precedence) · CPC title

• Y10S417/00

  Pumps · CPC title

• B05C5/0225 Primary

  characterised by flow controlling means, e.g. valves, located proximate the outlet (B05C5/0258, B05C5/0275 take precedence; supply valves upstream the coating head B05C11/1036) · CPC title

• F04B49/22 Primary

  by means of valves (F04B49/03 takes precedence) · CPC title