Pressure distribution sensor and sensing method

• US 20070113681A1
• Filed: 11/22/2005
• Published: 05/24/2007
• Est. Priority Date: 11/22/2005
• Status: Active Grant

• 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
• Granted Patent: US 7,331,245 B2
• Time in Patent Office: Days
• US Class Current: 73/862.46
• 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 sensor array comprising an array of pressure sensors, each of the pressure sensors operable to produce a respective pressure signal in response to pressure applied thereto, the pressure signal quantifying the pressure with greater than single-bit resolution; and

a processor operable in response to the pressure signals to generate an information signal representing a spatial distribution of pressure applied to the sensor array.

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

3. The apparatus of claim 1, in which the information signal represents the position in the array of the centroid of a region of the 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 array of the center of pressure of the pressure applied to the 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 sensor array.

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

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

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

12. The apparatus of claim 1, in which the pressure signal quantifies the pressure applied to the pressure sensor using one of three or more possible values.

13. The apparatus of claim 1, in which:

the apparatus additionally comprises a sensing area for sensing pressure applied thereto; and

the sensor array is located within the sensing area.

14. The apparatus of claim 1, in which:

the sensor array constitutes part of a first position sensor;

the sensing area additionally comprises a second position sensor having a different spatial resolution than the first position sensor; and

the processor is additionally operable to generate a position signal in response to respective position signals generated by the first position sensor and the second position sensor.

15. The apparatus of claim 14, in which the processor is further operable to ignore the position signal generated by the second pressure sensor when pressure applied thereto is less than a threshold pressure.

16. The apparatus of claim 14, additionally comprising a contact surface associated with the sensor array, 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.

17. The apparatus of claim 14, in which the first position sensor and the second position sensor are arranged in tandem.

18. The apparatus of claim 1, in which the pressure sensors comprise a material having an electrophysical property that depends on applied pressure.

19. The apparatus of claim 17, in which the pressure sensors comprise piezoelectric material.

20. The apparatus of claim 17, in which the pressure sensors comprise electrets.

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

22. A method, comprising:

at each pressure sensor in an array of pressure sensors, generating a pressure signal quantifying pressure applied to the pressure sensor with greater than single-bit resolution; and

generating from the pressure signals an information signal representing a spatial distribution of pressure applied to the array of pressure sensors.

23. The method of claim 22, 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 array of pressure sensors.

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

25. The method of claim 24, 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.

26. The method of claim 22, further comprising detecting a click event in response to the signal representing the temporal change.

27. The method of claim 22, in which the pressure signal quantifies the pressure applied to the pressure sensor using one of three or more possible values.