Method and apparatus for preventing degradation of electrostatically actuated devices

• US 6,467,879 B1
• Filed: 10/16/2000
• Issued: 10/22/2002
• Est. Priority Date: 10/16/2000
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Kubby, Joel A., Gulvin, Peter M., Eklund, Elliott A.
• Primary Examiner(s): Gordon, Raquel Yvette
• Application Number:
  US09/687,096
• Time in Patent Office: 736 Days
• Field of Search: 347/54, 347/68, 347/69, 347/70, 347/71, 347/72, 347/50, 347/40, 399/261, 361/700, 298/901, 310/328-330
• US Class Current: 347/54
• CPC Class Codes: B41J 2/14314 Structure of ink jet print heads with electrostatically actuated membrane
• CPC Class Codes: B81B 2201/036 Micropumps
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2201/052 Ink-jet print cartridges
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81B 2203/053 Translation according to an axis perpendicular to the substrate
• CPC Class Codes: B81B 3/0051 For defining the movement, i.e. structures that guide or limit the movement of an element mechanical arrangements for preventing or damping vibration or shock H01H3/60
• CPC Class Codes: F04B 43/043 Micropumps

Abstract

A micro-electromechanical fluid ejector having an inner structure on the bottom of the top of the membrane for isolating the conductor, and an outer structure, away from the center of the membrane, on the bottom of the top of the membrane to stop excessive flexing of the membrane leading to inter-electrode contact.

Claims

1. An electrostatic device, comprising:

a substrate having an insulating layer thereon;

a conductor formed on said insulating layer;

a membrane adjacent to said conductor; and

an actuator chamber formed between said membrane and said conductor, said membrane flexing toward said conductor when a voltage bias is applied thereto, said membrane having (i) a membrane top;

(ii) membrane sides for supporting said membrane above said conductor and said insulating layer;

(iii) an inner protrusion structure, located on said membrane top, for preventing said membrane top from touching said conductor; and

(iv) an outer protrusion structure, surrounding said inner protrusion structure, on said membrane top for reducing excessive flexing of said membrane top.

2. The electrostatic device as claimed in claim 1, wherein said inner protrusion structure and said outer protrusion structure, contact corresponding landing pads positioned on said conductor.

3. The electrostatic device as claimed in claim 2, wherein said landing pads that contact said outer protrusion structure are electrically isolated.

4. The electrostatic device as claimed in claim 1, wherein said conductor, said membrane, and said actuator chamber are each formed by surface micromachining.

5. The electrostatic device as claimed in claim 1, wherein said membrane top comprises one of a plurality of shapes.

6. The electrostatic device as claimed in claim 1, wherein said conductor comprises one of a plurality of shapes.

7. The electrostatic device as claimed in claim 1, further including a power source is connected between said conductor and said membrane for supplying sufficient force to deflect said membrane top towards said conductor.

8. The electrostatic device as claimed in claim 1, wherein said outer protrusion structure is radial.

9. The electrostatic device as claimed in claim 1, wherein said substrate is a semiconductor substrate.

10. The electrostatic device as claimed in claim 1, wherein said substrate is an insulating substrate.

11. The electrostatic device as claimed in claim 1, wherein said membrane is made of a material selected from said group consisting of silicon, polysilicon, glass and thin metallic film.