Pressure distribution sensor and sensing method

• US 7,331,245 B2
• Filed: 11/22/2005
• Issued: 02/19/2008
• Est. Priority Date: 11/22/2005
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Hardcastle, Ian, Nishimura, Ken A
• Primary Examiner(s): Lefkowitz; Edward
• Assistant Examiner(s): DUNLAP, JONATHAN M
• Application Number:
  US11/286,193
• Publication Number:
  US 20070113681A1
• Time in Patent Office: 819 Days
• Field of Search: 738/620.46, 738/18, 738/620.4, 345/174
• US Class Current: 73/862.046
• CPC Class Codes: G06F 3/04144 using an array of force sensing means position sensing using the local deformation of sensor cells G06F3/0447

Abstract

A spatial pressure distribution sensor comprises a sensor array and a processor. The sensor array comprises an array of pressure sensors. Each of the pressure sensors is operable to generate a respective pressure signal in response to pressure applied to it. The pressure signal quantifies the pressure with greater than single-bit resolution. The processor is operable in response to the pressure signals to generate an information signal representing the spatial distribution of pressure applied to the sensor array.

Claims

1. An apparatus, comprising:

a fine sensor array comprising an array of fine pressure sensors and a coarse sensor array comprising an array of coarse pressure sensors wherein the fine sensor array and the coarse sensor array are positioned to overlap, the fine and coarse pressure sensors operable to produce respective pressure signals in response to pressure applied thereto, at least some of the pressure signals quantifying the pressure with greater than single-bit resolution, the coarse sensor array having a different spatial resolution than the fine sensor array; and

a processor operable in response to the pressure signals to generate an information signal representing a spatial distribution of pressure applied to at least one of the fine sensor array and the coarse sensor array.

2. The apparatus of claim 1, in which the information signal represents the position in the fine sensor array of one of the fine pressure sensors producing the greatest of the pressure signals from the fine sensor array.

3. The apparatus of claim 1, in which the information signal represents the position in the fine sensor array of the centroid of a region of the fine pressure sensors each producing a respective pressure signal representing the same pressure applied thereto.

4. The apparatus of claim 1, in which the information signal represents the position in the fine sensor array of the center of pressure of the pressure applied to the fine sensor array.

5. The apparatus of claim 1, in which the processor is operable to generate the information signal to represent a temporal change in the spatial distribution of the pressure applied to the fine sensor array.

6. The apparatus of claim 5, in which the temporal change in the spatial distribution of the pressure applied to the fine sensor array is a result of lateral movement relative to the fine sensor array of the spatial distribution of the pressure.

7. The apparatus of claim 5, in which the processor is further operable to compare the spatial distribution of pressure to a previous spatial distribution of pressure to determine a vector representing magnitude and direction of a change in the spatial distribution of pressure and to generate the information signal to represent the vector.

8. The apparatus of claim 5, in which the processor is further operable to compare the pressure signals to a threshold value and to indicate a click event when at least one of the pressure signals has a value greater than the threshold value.

9. The apparatus of claim 1, in which the fine sensor array is a rectangular array.

10. The apparatus of claim 9, in which the fine sensor array additionally comprises a circular array of pressure sensors.

11. The apparatus of claim 1, in which the fine sensor array is a circular array.

12. The apparatus of claim 1, in which at least some of the pressure signals quantify the pressure applied to the respective pressure sensors using one of three or more possible values.

13. The apparatus of claim 1 wherein the coarse pressure sensors are larger in area than the fine pressure sensors.

14. The apparatus of claim 1, in which the processor is further operable to ignore the position signal generated by one of the fine and coarse pressure sensors when pressure applied thereto is less than a threshold pressure.

15. The apparatus of claim 1, additionally comprising a contact surface associated with at least one of the fine and coarse sensor arrays, the contact surface having a static coefficient of friction and a sliding coefficient of friction, the static coefficient of friction and the sliding coefficient of friction having a ratio greater than a threshold ratio.

16. The apparatus of claim 1, further comprising a contact layer and a substrate, the fine and coarse sensor arrays being positioned between the contact layer and the substrate such that one of the fine and coarse sensor arrays is positioned between the substrate and the other sensor array.

17. The apparatus of claim 1, in which at least some of the fine and coarse pressure sensors comprise a material having an electrophysical property that depends on applied pressure.

18. The apparatus of claim 17, in which at least some of the fine and coarse pressure sensors comprise piezoelectric material.

19. The apparatus of claim 17, in which at least some of the fine and coarse pressure sensors comprise electrets.

20. The apparatus of claim 1, in which the apparatus constitutes part of one of a touchpad, a touch screen, a slidepad and a mouse.

21. A method, comprising:

generating pressure signals quantifying pressure applied to pressure sensors in a fine sensor array of pressure sensors and a coarse sensor array of pressure sensors, the fine sensor array and coarse sensor array being positioned to overlap, at least some of the pressure signals quantifying the pressure with greater than single-bit resolution, the coarse sensor array having a different spatial resolution than the fine sensor array; and

generating from the pressure signals an information signal representing a spatial distribution of pressure applied to at least one of the fine and coarse sensor arrays of pressure sensors.

22. The method of claim 21, additionally comprising generating, in response to successive values of the information signal, a signal representing a temporal change in the spatial distribution of the pressure applied to the fine sensor array of pressure sensors.

23. The method of claim 22, in which the temporal change in the spatial distribution of the pressure applied to the fine sensor array of pressure sensors is a result of lateral movement relative to the fine sensor array of the spatial distribution of the pressure.

24. The method of claim 23, additionally comprising moving an object in response to the signal representing the temporal change, the movement of the object following the lateral movement of the spatial distribution of the pressure.

25. The method of claim 21, further comprising detecting a click event in response to the signal representing the temporal change.

26. The method of claim 21, in which at least some of the pressure signals quantify the pressure applied to the pressure sensors using one of three or more possible values.