Pointing stick device

• US 20090309832A1
• Filed: 06/13/2008
• Published: 12/17/2009
• Est. Priority Date: 06/13/2008
• Status: Active Grant

• Current Assignee: Wei Zhang
• Original Assignee: Wei Zhang
• Inventors: Zhang, Wei
• Granted Patent: US 8,593,403 B2
• Time in Patent Office: Days
• US Class Current: 345/161
• CPC Class Codes: G06F 3/0338 with detection of limited linear or angular displacement of an operating part of the device from a neutral position, e.g. isotonic or isometric joysticks

Abstract

The present invention provides a pointing stick device circuit which is using fewer components. The circuit is using current sources instead of voltage sources. This will be more convenient to integrate the circuit and largely reduce the cost. Also, using this circuit and the relative process, the requirement of high quality and low tolerance of some critical components is reduced. The performance of the device is improved.

Claims

1. A pointing stick device, comprising:

a signal source element which comprises a plurality of strain gauges for sensing forces exerted onto a pointing stick and generating voltage signals;

a voltage approaching element providing an incremental voltage for comparing with said voltage signals generated by said signal source element, wherein said voltage approaching element comprises a voltage division circuit providing a predetermined voltage to said incremental voltage according to said strain gauges of said signal source element, a first approaching unit lifting said incremental voltage close to said voltage signals that said incremental voltage is lifted not exceeding to said voltage signals, and a second approaching unit lifting said incremental voltage linearly; and

a signal process element comparing said voltage signals of said signal source element and said incremental voltage of said voltage approaching element, and counting the time for said incremental voltage to reach to a level related to said voltage signals for calculating said forces exerted onto said pointing stick.

2. The device, as recited in claim 1, wherein said first approaching unit comprises a first current source and a first approaching capacitor, wherein said first current source charges said first approaching capacitor for a predetermined period of time to increase said voltage level of said first approaching unit to a predetermined level.

3. The device, as recited in claim 2, wherein said second approaching unit comprises a second current source and a second approaching capacitor, wherein said second current source charges said second approaching capacitor in such a manner to increase said voltage level of said second approaching unit linearly with a predetermined rate.

4. The device, as recited in claim 1, wherein a tolerance of said strain gauges is larger than 10%.

5. The device, as recited in claim 3, wherein a tolerance of said strain gauges is larger than 10%.

6. The device, as recited in claim 4, wherein said first approaching unit adjusts an error voltage of said voltage division circuit caused by said tolerance.

7. The device, as recited in claim 5, wherein said first approaching unit adjusts an error voltage of said voltage division circuit caused by said tolerance.

8. The device, as recited in claim 1, wherein said signal process element further comprises a comparator comparing said voltage signal with said incremental voltage and a counter counting the time for said incremental voltage to reach to a level related to said voltage signals.

9. The device, as recited in claim 6, wherein said signal process element further comprises a comparator comparing said voltage signal with said incremental voltage and a counter counting the time for said incremental voltage to reach to a level related to said voltage signals.

10. The device, as recited in claim 7, wherein said signal process element further comprises a comparator comparing said voltage signal with said incremental voltage and a counter counting the time for said incremental voltage to reach to a level related to said voltage signals.

11. The device, as recited in claim 1, wherein said signal process element further comprises a comparator comparing the sum of said voltage signal and said incremental voltage with a referent voltage, and a counter counting the time for said incremental voltage to reach to a level related to said voltage signals.

12. The device, as recited in claim 6, wherein said signal process element further comprises a comparator comparing the sum of said voltage signal and said incremental voltage with a referent voltage, and a counter counting the time for said incremental voltage to reach to a level related to said voltage signals.

13. The device, as recited in claim 7, wherein said signal process element further comprises a comparator comparing the sum of said voltage signal and said incremental voltage with a referent voltage, and a counter counting the time for said incremental voltage to reach to a level related to said voltage signals.

14. The device, as recited in claim 1, wherein said first approaching unit comprises a first voltage source, a first resister in serial, and a first approaching capacitor, wherein said first voltage source and said first resister charge said first approaching capacitor for a predetermined period of time to increase said voltage level of said first approaching unit to a predetermined level.

15. The device, as recited in claim 14, wherein said second approaching unit comprises a second voltage source, a second resister in serial, and a second approaching capacitor, wherein said second voltage source and said second resister charge said second approaching capacitor in such a manner to increase said voltage level of said second approaching unit linearly with a predetermined rate.

16. A method of sensing forces exerted on a pointing stick device, comprising the steps of:

(a) resetting a circuit of said pointing stick device;

(b) sampling a signal source from said circuit;

(c) increasing an incremental voltage via a first approaching unit to a predetermined voltage level;

(d) linearly increasing said incremental voltage via a second approaching unit at a predetermined linear incremental rate;

(e) comparing said voltage signal of said sampled signal source with said incremental voltage from said second approaching unit; and

(f) determining a time for said incremental voltage in responsive to said incremental rate thereof for calculating said force exerted onto said pointing stick device.

17. The method, as recited in claim 16, wherein, in step (c) further comprises steps:

(c1) connecting with a voltage division circuit; and

(c2) charging a first approaching capacitor for a predetermined period of time to increase said incremental voltage to reach said voltage level.

18. The method, as recited in claim 17, wherein, in step (d) further comprises a step:

(d1) linearly charging a second approaching capacitor to linearly increase said incremental voltage.

19. The method as recited in claim 17 wherein, in the step (c2), said first approaching capacitor is charged by a current source.

20. The method as recited in claim 18 wherein, in the step (d1), said second approaching capacitor is charged by a current source.

21. The method as recited in claim 16 wherein, in the step (b), said signal source is generated by strain gauges with a tolerance larger than 10%.

22. The method as recited in claim 18 wherein, in the step (b), said signal source is generated by strain gauges with a tolerance larger than 10%.

23. The method as recited in claim 19 wherein, in the step (b), said signal source is generated by strain gauges with a tolerance larger than 10%.

24. The method as recited in claim 16 wherein, in the step (f), said time is determined by said incremental voltage linearly increased at said incremental rate to reach said voltage signal.

25. The method as recited in claim 16 wherein, in the step (e) a comparator compares the sum voltage of said voltage signal and said incremental voltage with a referent voltage, wherein in the step (f) said time is determined by said incremental voltage linearly increased at said incremental rate to reach said voltage signal.

26. The method as recited in claim 20 wherein, in the step (f), said time is determined by said incremental voltage linearly increased at said incremental rate to reach said voltage signal.

27. The method as recited in claim 20 wherein, in the step (e) a comparator compares the sum voltage of said voltage signal and said incremental voltage with a referent voltage, wherein in the step (f) said time is determined by said incremental voltage linearly increased at said incremental rate to reach said voltage signal.

28. The method as recited in claim 17 wherein, in the step (c2), said first approaching capacitor is charged by a voltage source.

29. The method as recited in claim 18 wherein, in the step (d1), said second approaching capacitor is charged by a voltage source.