Micromachined fluid ejector systems and methods having improved response characteristics

• US 6,416,169 B1
• Filed: 11/24/2000
• Issued: 07/09/2002
• Est. Priority Date: 11/24/2000
• Status: Expired due to Term

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Crowley, Joseph M., Galambos, Paul C., Gooray, Arthur M., Givler, Richard C., Peter, Frank J., Roller, George J., Zavadil, Kevin R.
• Primary Examiner(s): Gordon, Raquel Yvette
• Application Number:
  US09/718,420
• Time in Patent Office: 592 Days
• Field of Search: 347/54, 347/68, 347/69, 347/70, 347/71, 347/72, 347/50, 347/40, 347/20, 347/44, 347/47, 347/27, 399/261, 361/700, 298/901, 310/328-330
• US Class Current: 347/54
• CPC Class Codes: B41J 2/14 Structure thereof only for on-demand ink jet heads
• CPC Class Codes: B41J 2002/043 Electrostatic transducer

Abstract

A piston structure is movably mounted within a fluid chamber. Movement of the piston structure towards a faceplate causes a portion of the fluid between the piston and the faceplate to be forced out of the nozzle hole in the faceplate, forming a drop or jet of the fluid. Viscous forces that are generated by the flow of fluid along a working surface of the piston structure toward and away from the nozzle hole generate a force that resists the movement of the piston structure. This resistance force tends to slow the piston motion, and prevents the piston from contacting the faceplate. In various embodiments, the fluid chamber is defined by a cylinder structure. The piston structure moves within the cylinder structure. The cylinder structure and the faceplate define the fluid chamber. The cylinder structure and the piston structure are designed to cooperate so that the movement of the piston structure within the cylinder structure ejects fluid according to various design criteria. In various embodiments, a free space is provided between the faceplate and the piston structure at its maximum displacement towards the faceplate.

Claims

1. A microelectromechanical system based fluid ejector, comprising:

a faceplate having at least one ejector nozzle;

a substrate on which the faceplate is mounted;

a cylinder structure between the faceplate and the substrate, the cylinder structure having a first endwall and a second endwall that at least partially define a chamber that communicates with the at least one ejector nozzle, the second end wall located a predetermined distance from the least one ejector nozzle; and

a movable piston arranged to move in the chamber away from the first endwall towards the second endwall with a predetermined maximum stroke, the predetermined maximum stroke being less than the predetermined distance such that viscous resistance against movement of the piston towards the second wall by a fluid in the chamber is primarily a result of sheer flow of the fluid between the piston and an inner circumference of the cylinder structure.

2. A microelectromechanical system based fluid ejector, comprising:

a faceplate having at least one ejector nozzle;

a substrate on which the faceplate is mounted;

a cylinder structure extending between the faceplate and the substrate, the cylinder structure having endwalls and sidewalls that at least partially define a chamber that communicates with the at least one ejector nozzle, the second end wall located a predetermined distance from the least one ejector nozzle; and

a movable piston arranged to move in the chamber with a predetermined maximum stroke, the predetermined maximum stroke being less than the predetermined distance such that viscous resistance against movement of the piston towards the second endwall by a fluid in the chamber varies substantially linearly with a stroke distance of the piston.

3. A microelectromechanical system based fluid ejector, comprising:

a faceplate having at least one ejector nozzle;

a cylinder structure extending from the faceplate a predetermined distance and having an inner circumference, the inner circumference defining a chamber that communicates with the at least one ejector nozzle; and

a movable piston arranged to move in the chamber with a predetermined maximum stroke, the predetermined maximum stroke being less than the predetermined distance such that viscous resistance against movement of the piston towards the faceplate by a fluid in the chamber is primarily a result of shear flow of the fluid between the piston and the inner circumference of the cylinder structure.

4. A microelectromechanical system based fluid ejector, comprising:

a faceplate having at least one ejector nozzle;

a cylinder structure extending from the faceplate a predetermined distance and having an inner circumference, the inner circumference defining a chamber that communicates with the at least one ejector nozzle; and

a movable piston arranged to move in the chamber with a predetermined maximum stroke, the predetermined maximum stroke being less than the predetermined distance such that viscous resistance against movement of the piston towards the faceplate by a fluid in the chamber varies substantially linearly with a stroke distance of the piston.

5. A microelectromechanical system based liquid ejector, comprising:

a faceplate having at least one ejector nozzle; and

a movable piston arranged to move within a fluid chamber towards the faceplate such that a drop of fluid is ejected from the fluid chamber through the at least one ejector nozzle;

wherein viscous resistance against movement of the piston towards the faceplate by the fluid in the fluid chamber prevents the piston from contacting the faceplate.

6. A method for ejecting a fluid using a microelectromechanical system based fluid ejector having a chamber within a cylinder structure between a faceplate and a substrate of the ejector, the cylinder structure having a first endwall and a second endwall, the second end wall located a predetermined distance from an ejector nozzle of the faceplate, the method comprising:

moving a movable piston within the cylinder structure away from the first endwall and towards the second endwall with a predetermined maximum stroke, the predetermined maximum stroke being less than the predetermined distance such that viscous resistance against movement of the piston towards the second wall by a fluid in the chamber is primarily a result of shear flow of the fluid between the piston and an inner circumference of the cylinder structure.

7. A method for ejecting a fluid using a microelectromechanical system based fluid ejector having a chamber within a cylinder structure between a faceplate and a substrate of the ejector, the cylinder structure having a first endwall and a second endwall, the second end wall located a predetermined distance from an ejector nozzle of the faceplate, the method comprising:

moving a movable piston within the cylinder structure away from the first endwall and towards the second endwall with a predetermined maximum stroke, the predetermined maximum stroke being less than the predetermined distance such that viscous resistance against movement of the piston towards the second endwall by a fluid in the chamber varies substantially linearly with a stroke distance of the piston.

8. A method for ejecting a fluid using a microelectromechanical system based fluid ejector having a chamber within a cylinder structure extending from a faceplate a predetermined distance, comprising:

moving a movable piston within the cylinder structure towards the faceplate with a predetermined maximum stroke, the predetermined maximum stroke being less than the predetermined distance such that viscous resistance against movement of the piston towards the faceplate by a fluid in the chamber is primarily a result of sheer flow of the fluid between the piston and the inner circumference of the cylinder structure.

9. A method for ejecting a fluid using a microelectromechanical system based fluid ejector having a chamber within a cylinder structure extending from a faceplate a predetermined distance, the method comprising:

moving a movable piston within the cylinder structure towards the faceplate with a predetermined maximum stroke, the predetermined maximum stroke being less than the predetermined distance such that viscous resistance against movement of the piston towards the faceplate by a fluid in the chamber varies substantially linearly with a stroke distance of the piston.

10. A method for ejecting fluid using a microelectromechanical system based fluid ejector, comprising:

moving a movable piston within a fluid chamber towards a faceplate having at least one ejector nozzle such that a drop of fluid is ejected from the fluid chamber through the at least one ejector nozzle; and

preventing the piston from contacting the faceplate based on viscous resistance against movement of the piston towards the faceplate by the fluid in the fluid chamber.