Pressure measurement using a MEMS device

• US 7,860,668 B2
• Filed: 06/18/2008
• Issued: 12/28/2010
• Est. Priority Date: 06/18/2008
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Khazeni, Kasra
• Primary Examiner(s): Lau; Tung S
• Assistant Examiner(s): Sun; Xiuquin
• Application Number:
  US12/141,326
• Publication Number:
  US 20090319220A1
• Time in Patent Office: 923 Days
• Field of Search: 702/47, 417/413.2, 307/52
• US Class Current: 702/47
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm
• CPC Class Codes: G01L 9/0086 using variations in capacitance

Abstract

A device to measure pressure is disclosed. In one embodiment, the device includes at least one element with two layers separated by a space which changes over a variable time period in response to a voltage applied across the two layers. The time period may be measured and indicative of the ambient pressure about the device.

Claims

1. A device for measuring pressure comprising:

at least one element comprising two layers separated by a space, wherein a dimension of the space changes over a variable time period in response to a voltage applied across the two layers; and

a measuring module configured to measure the time period, wherein the time period is the time between when a voltage is applied and when a motion of at least one of the layers reaches a maximum velocity and is indicative of the ambient pressure about the device.

2. The device of claim 1, wherein the time period is a linear function of the ambient pressure about the device.

3. The device of claim 1, wherein the time period is measured by measuring the current induced by a motion of at least one of the layers.

4. The device of claim 1, wherein the device comprises a plurality of elements arranged to provide redundancy in the measurement of the time period.

5. The device of claim 1, wherein the device outputs the ambient pressure to a user of the device.

6. The device of claim 1, wherein the ambient pressure is indicative of an altitude, and wherein the device outputs the altitude to a user of the device.

7. The device of claim 1, wherein the measuring module is configured to repeatedly measure the time period to continuously monitor the ambient pressure about the device.

8. The device of claim 1, further comprising a control module to apply a voltage across the two layers.

9. The device of claim 8, wherein the applied voltage is a square wave.

10. The device of claim 1, further comprising:

a display;

a processor that is configured to communicate with said display, said processor being configured to process image data; and

a memory device that is configured to communicate with said processor.

11. The device of claim 10, further comprising a driver circuit configured to send at least one signal to the display.

12. The device of claim 11, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

13. The device of claim 10, further comprising an image source module configured to send said image data to said processor.

14. The device of claim 13, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

15. The device of claim 10, further comprising an input device configured to receive input data and to communicate said input data to said processor.

16. A method of measuring pressure comprising:

applying a voltage across two layers of a microelectromechanical device;

measuring a response time of the device, wherein the response time is the time between when the voltage is applied and when a motion of at least one of the layers reaches a maximum velocity; and

determining a pressure about the device based on the measured response time.

17. The method of claim 16, wherein the response time is measured by measuring an electrical current induced by a motion of at least one of the layers.

18. A device for measuring pressure comprising:

means for applying a voltage across layers of a microelectromechanical device;

means for measuring a response time of the device, wherein the response time is the time between when the voltage is applied and when a motion of at least one of the layers reaches a maximum velocity; and

means for determining a pressure about the device based on the measured response time.

19. The device of claim 18, wherein the means for applying comprises at least one of a processor, a controller, and a driver.

20. The device of claim 18, wherein the means for measuring comprises at least one of a measuring module and an ammeter.

21. The device of claim 18, wherein the means for determining comprises a processor.

22. A device for measuring pressure comprising:

at least one element comprising two conductive layers separated by a space, wherein a dimension of the space changes over a variable time period in response to a change in voltage applied across the two layers;

a measuring module configured to measure current flowing between the two conductive layers as a function of time when there is a change in voltage applied between the two conductive plates; and

a processor configured to determine the time difference between when the voltage pulse is applied and when the local maximum of the motion current occurs, wherein the processor is further configured to associate the time difference with an ambient pressure.