Free-fall detection device and free-fall protection system for a portable electronic apparatus

• US 20060152842A1
• Filed: 06/24/2005
• Published: 07/13/2006
• Est. Priority Date: 06/28/2004
• Status: Active Grant

• Current Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Tronconi, Michele, Pasolini, Fabio, Lin, Wen, Raasch, William R.
• Granted Patent: US 7,450,332 B2
• Time in Patent Office: Days
• US Class Current: 360/75
• CPC Class Codes: G01P 15/0891 with indication of predetermined acceleration values G01P15/135 takes precedence
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G11B 19/04 Arrangements for preventing, inhibiting, or warning against double recording on the same blank or against other recording or reproducing malfunctions

Abstract

In an integrated free-fall detection device for a portable apparatus an acceleration sensor generates acceleration signals correlated to the components of the acceleration of the portable apparatus along three detection axes. A dedicated purely hardware circuit connected to the acceleration sensor generates a free-fall detection signal in a continuous way and in real-time. The free-fall detection signal has a first logic value in the event that the acceleration signals are simultaneously lower than a respective acceleration threshold, and is sent to a processor unit of the portable apparatus as an interrupt signal to activate appropriate actions of protection for the portable apparatus. Preferably, the acceleration sensor and the dedicated purely hardware circuit are integrated in a single chip and the acceleration sensor is made as a MEMS.

Claims

1. A free-fall detection device for a portable apparatus comprising:

an acceleration sensor generating at least a first and a second acceleration signal correlated to a respective component of a sensed acceleration along a respective detection axis; and

a free-fall detection module coupled to said acceleration sensor, wherein said free-fall detection module is configured to carry out a comparison between each one of said first and second acceleration signals and a respective acceleration threshold, and to generate a free-fall detection signal according to the result of both comparisons.

2. The device of claim 1, wherein said acceleration sensor further generates a third acceleration signal, and said free-fall detection module is configured to carry out a further comparison between said third acceleration signal and a respective acceleration threshold, and to generate said free-fall detection signal according to the result of said both comparisons and said further comparison.

3. The device of claims 2, wherein said free-fall detection signal has a first logic value in the event that said first, second and third acceleration signals are simultaneously lower than the respective acceleration threshold.

4. The device of claim 1, wherein said respective acceleration threshold is not higher than 1/√

{square root over (3)}·

g.

5. The device of claim 4, wherein said respective acceleration threshold is equal to 350 mg.

6. The device of claim 1, wherein said free-fall detection module comprises a dedicated purely hardware circuit generating in a continuous way and in real-time said free-fall detection signal.

7. The device of claim 6, wherein said acceleration sensor and said dedicated purely hardware circuit are integrated in a single chip, said acceleration sensor being made as a MEMS.

8. The device of claim 6 for a portable apparatus provided with a processor unit, wherein said dedicated purely hardware circuit has an output supplying said free-fall detection signal and configured to be connected to said processor unit.

9. The device of claim 6, wherein said dedicated purely hardware circuit comprises a comparison stage configured to carry out said comparison, and a detection stage connected to said comparison stage and generating said free-fall detection signal.

10. The device of claim 9, wherein said comparison stage comprises a threshold comparator for each of said acceleration signals, each of said threshold comparators receiving one respective of said acceleration signals and said respective acceleration threshold, and generating at output a respective logic signal;

and wherein said detection stage comprises an AND logic gate receiving said logic signals.

11. The device of claim 10, wherein said detection stage further comprises false-detection rejecting means, connected to said AND logic gate and outputting said free-fall detection signal.

12. The device of claim 11, wherein said false-detection rejecting means comprise a counter receiving a clock signal and the logic signal outputted by said AND logic gate as count-enable signal;

and a threshold comparator receiving the count signal generated by said counter and a count threshold, said threshold comparator generating said free-fall detection signal.

13. The device of claim 12, further comprising a first storage means for storing said respective acceleration threshold.

14. The device of claim 6, wherein said dedicated hardware circuit further comprises an enabling stage, which is connected to said comparison stage and receives an enabling signal for each of said detection axes;

said enabling stage being configured to enable/disable detection of free-fall along each of said detection axes.

15. The device of claim 6, wherein said dedicated hardware circuit further comprises second storage means for storing the occurrence of said free-fall detection signal.

16. A free-fall protection system for a portable apparatus, comprising:

(a) a free-fall detection device configured to issue a warning signal upon detecting a free-fall condition of said portable apparatus, including;

(i) an acceleration sensor generating at least a first and a second acceleration signal correlated to a respective component of a sensed acceleration along a respective detection axis; and

(ii) a free-fall detection module coupled to said acceleration sensor, and configured to carry out a comparison between each one of said first and second acceleration signals and a respective acceleration threshold, and to generate a free-fall detection signal according to the result of both comparisons; and

(b) a protection device connected to said free-fall detection device and configured to activate protection actions for said portable apparatus upon receiving said warning signal.

17. The system of claim 16, wherein said protection device comprises a processor unit connected to an output of said free-fall detection device and having an interrupt input, said processor unit receiving at said interrupt input said warning signal for activating said protection actions.

18. The system of claim 17, wherein said free-fall detection device comprises first storage means for storing said respective acceleration threshold, and wherein said processor unit is further connected to said first storage means and configured to program said respective acceleration threshold.

19. The system of claim 16 further comprising a data-storage device, wherein said protection device is configured to be connected to said data-storage device and said protection actions are intended to protect said data storage device from damage due to said free-fall condition.

20. The system of claim 19, wherein said data-storage device comprises a read/write head, and said protection actions comprise issuing a command for parking said read/write head in a safe position of said data-storage device.

21. A portable apparatus, comprising:

(a) a free-fall detection device configured to issue a warning signal upon detecting a free-fall condition of said portable apparatus, comprising;

(i) an acceleration sensor generating at least a first and a second acceleration signal correlated to a respective component of a sensed acceleration along a respective detection axis; and

(ii) a free-fall detection module coupled to said acceleration sensor, and configured to carry out a comparison between each one of said first and second acceleration signals and a respective acceleration threshold, and to generate a free-fall detection signal according to the result of both comparisons; and

(b) a protection device connected to said free-fall detection device and configured to activate protection actions for said portable apparatus upon receiving said warning signal.

22. The apparatus of claim 21, further comprising a a data storage device having a read/write head and wherein said protection device further comprises a processor unit, wherein said processor until controls a displacement of said read/write head according to said warning signal.

23. The apparatus of claim 22, wherein said free-fall detection device and said protection device are arranged within said data-storage device.

24. The apparatus of claim 23, wherein said apparatus is selected from the group consisting of laptop computers, personal data assistants, digital audio players, mobile phones, and digital cameras.

25. A data storage device comprising:

(I) a data storage medium;

(II) a read/write head associated with said data storage medium; and

(III) a free-fall protection system comprising;

(a) a free-fall detection device configured to issue a warning signal upon detecting a free-fall condition of said data-storage device, comprising;

(i) an acceleration sensor generating at least a first and a second acceleration signal correlated to a respective component of a sensed acceleration along a respective detection axis; and

(ii) a free-fall detection module coupled to said acceleration sensor and configured to carry out a comparison between each one of said first and second acceleration signals and a respective acceleration threshold and to generate a free-fall detection signal; and

(b) a protection device connected to said free-fall detection device and configured to activate protection actions for said data storage device upon receiving said warning signal.

26. The data storage device of claim 25, wherein said free-fall protection system is configured to control a parking of said read/write head in a safe position upon detecting said free-fall condition.

27. A method for protecting a portable apparatus from a free-fall event comprising:

detecting a free-fall condition of said portable electronic apparatus based on an acceleration of said portable electronic apparatus;

wherein said detecting a free-fall condition comprises;

acquiring at least a first and a second acceleration signal correlated to a respective component of said acceleration along a respective detection axis;

comparing each one of said first and second acceleration signals with a respective acceleration threshold;

detecting said free-fall condition according to the result of both comparisons; and

activating protection actions for said portable apparatus upon detection of said free-fall condition.

28. The method according to claim 27, further comprising acquiring a third acceleration signal, and comparing said third acceleration signal with a respective acceleration threshold.

29. The method according to claim 28, wherein said free-fall condition is detected in the event said acceleration signals are simultaneously lower than the respective acceleration threshold.

30. The method according to claim 28, wherein said free-fall condition is detected in the event said acceleration signals are simultaneously lower than the respective acceleration threshold for a preset time interval.

31. The method according to claim 27, wherein said portable apparatus includes a processor unit and the activating step includes issuing an interrupt to said processor unit.