Integrated force sensitive lens and software

• US 20090066673A1
• Filed: 01/23/2008
• Published: 03/12/2009
• Est. Priority Date: 09/07/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: F-Origin, Inc.
• Inventors: Molne, Anders L., Klimov, Konstantin, Leinonen, Toni, Carsanaro, Joseph
• Granted Patent: US 8,026,906 B2
• Time in Patent Office: Days
• US Class Current: 345/178
• CPC Class Codes: G06F 3/0414 using force sensing means to determine a position
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment

Abstract

A software compensation method that allows a touch sensitive display to be built using low-cost FSR force sensors The compensation method comprises an array of functional compensation modules including filtering, voltage conversion, temperature compensation, humidity compensation, sensor calibration, sensor reading linearization, auto calibration, positioning determination and finally end-user and mechanical calibration. The array of compensation modules can bring system accuracy from a non-compensated average positioning error in the 25% to 50% range, down to aN end-user acceptable range of 0% to 5%. The increased positioning accuracy makes it possible to use FSRs as opposed to traditional piezoresistive based touch screen sensors.

Claims

1. A software method for improving touch precision of a differential force-sensor touchscreen, comprising a software module for linearization and homogenization of sensor data.

2. The software method of claim 1, wherein said differential force-sensor touchscreen comprises a plurality of FSR sensors.

3. The software method of claim 1, wherein said differential force-sensor touchscreen comprises a plurality of piezo resistive sensors.

4. The software method of claim 1, wherein said differential force-sensor touchscreen comprises a plurality of nano technology-based force sensor.

5. The software method of claim 1, wherein said software method further comprises a software module for temperature compensation of sensor data.

6. The software method of claim 5, wherein said software method further comprises a software module for auto calibration and preloading compensation of sensor data.

7. The software method of claim 6, wherein said software method further comprises a software module for humidity compensation of sensor data.

8. The software method of claim 7, wherein said software method further comprises a software module for voltage compensation of sensor data.

9. The software method of claim 8, wherein said software method further comprises a software module for filtering of sensor data noise.

10. The software method of claim 9, wherein said software method further comprises a software module for material calibration of said touchscreen.

11. The software method of claim 1, wherein said software method further comprises one or more software modules for data filtering, voltage conversion, sensor calibration, sensor reading linearization, auto calibration, positioning determination and finally end-user and mechanical calibration.

12. A software method for improving touch precision of a differential force-sensor touchscreen, comprising a software module for compensation of sensor data.

13. The software method of claim 12, wherein said differential force-sensor touchscreen comprises a plurality of FSR sensors.

14. The software method of claim 12, wherein said differential force-sensor touchscreen comprises a plurality of piezo resistive sensors.

15. The software method of claim 12, wherein said differential force-sensor touchscreen comprises a plurality of nano technology-based force sensor.

16. The software method of claim 12, wherein said software module for compensation of sensor data further comprises a software module for linearization and homogenization of sensor data.

17. The software method of claim 16, wherein said software module for linearization and homogenization of sensor calculates an absolute force applied on a sensor by the following function:

Y=A_n*Xⁿ+A_n-1*X^n-1+ . . . +A₂*X²+A₁*X¹+A₀

where

X is an output value of the sensor;

Y is a calculated value of force in mg;

n is a degree of polynomial function; and

An . . . A0 are predetermined coefficients.

18. The software method of claim 12, wherein said software module for compensation of sensor data further comprises a software module for temperature compensation of sensor data.

19. The software method of claim 18, wherein said temperature compensation module compensates said sensor data based on prior sensor readings.

20. The software method of claim 19, wherein said temperature compensation module compensates said sensor data based on a moving average of prior sensor readings.

21. The software method of claim 12, wherein said software module for compensation of sensor data further comprises a software module for auto calibration and preloading compensation of sensor data.

22. The software method of claim 12, wherein said software module for compensation of sensor data further comprises a software module for humidity compensation of sensor data.

23. The software method of claim 12, wherein said software module for compensation of sensor data further comprises a software module for voltage compensation of sensor data.

24. The software method of claim 12, wherein said software module for compensation of sensor data further comprises a software module for filtering of sensor data noise.

25. The software method of claim 12, wherein said software module for compensation of sensor data further comprises a software module for material calibration of said touchscreen.

26. A differential-force touchscreen display for a portable electronic device, comprising:

a display module from among a group including an LCD display module, OLED display module, touch lens module or touch pad module;

a plurality of FSR force sensors in operative contact with said display panel;

a processor in communication with said FSR force sensors, said processor having associated memory;

a software program resident in said processor memory or external memory accessible to the processor, for improving touch precision of said touchscreen, said software comprising a function for linearization and homogenization of sensor data.

27. The differential-force touchscreen display of claim 26, wherein said software method further comprises a function for temperature compensation of sensor data.

28. The differential-force touchscreen display of claim 26, wherein said software method further comprises a function for auto calibration and preloading compensation of sensor data.

29. The differential-force touchscreen display of claim 26, wherein said software method further comprises a function for humidity compensation of sensor data.

30. The differential-force touchscreen display of claim 26, wherein said software method further comprises a function for voltage compensation of sensor data.

31. The differential-force touchscreen display of claim 26, wherein said software method further comprises a function for filtering of sensor data noise.

32. The differential-force touchscreen display of claim 26, wherein said software method further comprises a function for material calibration of said touchscreen.

33. The differential-force touchscreen display of claim 26, wherein said software method further comprises a plurality of functions for data filtering, voltage conversion, sensor calibration, sensor reading linearization, auto calibration, positioning determination and finally end-user and mechanical calibration.

34. A differential-force touchscreen display for a portable electronic device, comprising:

a display module;

an FSR force sensor;

a plastic housing enveloping said FSR force sensor and maintaining operative contact with said display module, said plastic housing imparting a compressive preload on said force sensor.