Vibration compensated pressure sensing assembly

• US 6,293,154 B1
• Filed: 12/10/1999
• Issued: 09/25/2001
• Est. Priority Date: 12/10/1999
• Status: Expired due to Term

• Current Assignee: Kulite Semiconductor Products Inc
• Original Assignee: Kulite Semiconductor Products Inc
• Inventors: Kurtz, Anthony D.
• Primary Examiner(s): OEN, WILLIAM L
• Application Number:
  US09/459,238
• Time in Patent Office: 655 Days
• Field of Search: 737/08, 737/20, 737/21, 737/26, 737/27, 338/4, 338/42
• US Class Current: 73/727
• CPC Class Codes: G01L 19/02 Arrangements for preventing, or for compensating for, effects of inclination or acceleration of the measuring device; Zero-setting means for aneroid barometers G01L7/14
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm

Abstract

A pressure sensing device for producing an output proportional to an applied pressure irrespective of vibration and acceleration of the device, the device including: a first deflecting diaphragm formed in a first wafer and including a first plurality of piezoresistors mounted thereon, the first diaphragm being responsive to the applied pressure and vibration of the device; and, a second deflecting diaphragm formed in the first wafer and including a second plurality of piezoresistors mounted thereon, the second diaphragm being responsive only to vibration of the device; wherein, the first and second pluralities of piezoresistors are electrically coupled together to provide a common output such that they cooperatively at least partially cancel a portion of the common output associated with the vibration of the device.

Claims

1. A pressure sensing device for producing an output proportional to an applied pressure irrespective of vibration and acceleration of said device, said device comprising:

a wafer including first and second recessed portions respectively defining first and second deflectable diaphragms;

a first plurality of piezoresistors mounted on said first deflectable diaphragm and being responsive to said applied pressure and vibration of said device; and

,

a second plurality of piezoresistors mounted on said second deflectable diaphragm and being responsive to said vibration of said device;

wherein, said first and second pluralities of piezoresistors are electrically coupled together to provide a common output such that they cooperatively at least partially cancel a portion of said common output associated with said vibration of said device.

2. The device of claim 1, further comprising a covering member including a aperture there through, said covering member being secured to said wafer such that said aperture is above said first diaphragm.

3. The device of claim 2, wherein said covering member isolates said second diaphragm from said applied pressure.

4. The device of claim 3, wherein said first and second diaphragms each respectively include first and second sides, wherein said plurality of piezoresistors of said first pressure transducer are mounted to said first side of said first diaphragm, and said second side of said first diaphragm is exposed to said aperture.

5. The device of claim 4, wherein said plurality of piezoresistors of said second pressure transducer are mounted to said first side of said second diaphragm and said second plurality of piezoresistors are responsive only to said vibration and acceleration of said device.

6. The device of claim 1, wherein one of said plurality of piezoresistors increases in resistance and another of said first plurality of piezoresistors decreases in resistance in response to positive deflection of said first diaphragm.

7. The device of claim 1, wherein physical properties of said first and second diaphragms are substantially identical, and electrical characteristics of each of said first and second pluralities of piezoresistors are substantially identical.

8. The device of claim 1, wherein said first and second diaphragms are formed in sufficiently close proximity to one another they are subjected to nearly identical stresses when said device is exposed to vibrations or accelerations.

9. A pressure sensing assembly comprising:

a wafer including first and second recessed portions respectively forming first and second deflectable diaphragms, and first and second circuit elements each respectively formed on an associated one of said first and second diaphragms, said first and second circuit elements each being adapted to provide an output indicative of an amount of deflection of said associated diaphragm and being electrically coupled together; and

,

a member including an aperture passing there through, said member being secured to said wafer such that said aperture is positioned above said first diaphragm;

whereby, when said device is exposed to said pressure to be measured, said first diaphragm is exposed to said pressure through said aperture and said output of said first and second circuits at least partially cancel.

10. The apparatus of claim 9, wherein said member isolates said second diaphragm from said applied pressure.

11. The apparatus of claim 10, wherein said first and second diaphragms have substantially identical physical characteristics and are formed in close proximity to one another.

12. The apparatus of claim 11, wherein said first circuit comprises a first plurality of piezoresistive devices and said second circuit comprises a second plurality of piezoresistive devices, and each of said first and second pluralities of piezoresistive devices have substantially identical electrical characteristics.

13. The device of claim 12, wherein one of said first plurality of piezoresistors increases in resistance and another of said first plurality of piezoresistors decreases in resistance in response to positive deflection of said first diaphragm.

14. The device of claim 9, wherein said first diaphragm isolates said first circuit from said aperture.

15. A method for eliminating an undesirable component in an output of a pressure sensing device resulting from vibration or acceleration of said device, said device comprising a plurality of deflectable diaphragms each having a piezoresistive network mounted thereon and being operable to provide a signal indicative of an amount of deflection of said diaphragm on which it is mounted, said method comprising:

simultaneously exposing a first of said diaphragms having a first piezoresistive network mounted thereon to said pressure to be measured while isolating a second of said diaphragms having a second piezoresistive network mounted thereon from said pressure to be measured; and

,

electrically coupling said first and second piezoresistive networks together so as to provide a common output indicative of said pressure to be measured such that they cooperatively at least partially cancel a portion of said common output associated with said vibration or acceleration.

16. The method of claim 15, wherein said first and second diaphragms are formed in a common wafer in close proximity to one another.

17. The method of claim 15, wherein each of said diaphragms has substantially identical physical characteristics and each of said piezoresistive networks has substantially identical electrical characteristics.

18. The method of claim 15, wherein said first piezoresistive network is formed on said first diaphragm so as to be isolated by said first from said aperture.

19. The method of claim 18, wherein said second piezoresistive network is formed on a same side of said wafer as said first piezoresistive network.

20. The method of claim 19, wherein said first and second piezoresistive networks and said first and second diaphragms are formed such that they are subjected to nearly identical stresses when said device is subjected to vibrations, accelerations and decelerations.