Portable device with freefall detection or audio processing subsystem and freefall detection or audio processing method

• US 20070223123A1
• Filed: 03/22/2006
• Published: 09/27/2007
• Est. Priority Date: 03/22/2006
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: PortalPlayer Inc (NVIDIA Corporation)
• Inventors: Karakas, Ahmet
• Granted Patent: US 7,751,142 B2
• Time in Patent Office: Days
• US Class Current: 360/31
• 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 a class of embodiments, a method and apparatus for detecting freefall of a disk device (thereby predicting that the disk device will likely suffer imminent physical impact) and typically also preventing damage that a disk drive of the device would otherwise suffer if and when a predicted impact occurs. In some embodiments, a disk device includes a freefall detection processor and a CPU. The freefall detection processor is configured to monitor acceleration data to determine whether the disk device is in freefall and to perform at least one other operation (e.g., decoding of MP3-encoded audio data to generate decoded audio data) while the CPU performs at least one other task. Other embodiments pertain to a portable device including a digital audio processing subsystem and an accelerometer. The digital audio processing subsystem is configured to monitor acceleration data to identify any rhythm associated with motion of the portable device and to modify the playback of audio data in response to any such identified rhythm.

Claims

1. A method for determining that a disk device is in freefall, including the steps of:

(a) determining from acceleration data indicative of instantaneous acceleration of the disk device whether said instantaneous acceleration is less than gravitational acceleration during a first time interval of predetermined duration;

(b) determining from the acceleration data whether said instantaneous acceleration has a time derivative whose absolute magnitude exceeds a predetermined minimum value during a second time interval having a second predetermined duration; and

(c) determining that the disk device is in freefall by determining that said instantaneous acceleration is not less than gravitational acceleration during the first time interval and the absolute magnitude of the time derivative of said instantaneous acceleration does not exceed the predetermined minimum value during the second time interval.

2. The method of claim 1, wherein the predetermined minimum value of the time derivative of the instantaneous acceleration is at least substantially equal to zero.

3. The method of claim 1, wherein the acceleration data comprise samples generated during sample periods, the first time interval is a predetermined number of the most recent consecutive sample periods, and the second time interval is a second predetermined number of the most recent consecutive sample periods.

4. The method of claim 3, wherein the second time interval coincides with the first time interval.

5. The method of claim 1, wherein the second time interval coincides with the first time interval.

6. The method of claim 1, wherein one of the second time interval and the first time interval is a subinterval of but does not coincide with the other of said second time interval and said first time interval.

7. The method of claim 1, wherein step (b) includes the steps of:

generating derivative data indicative of the absolute magnitude of the time derivative of the instantaneous acceleration; and

determining from the derivative data whether the absolute magnitude of the time derivative of said instantaneous acceleration exceeds the predetermined minimum value during the second time interval.

8. The method of claim 1, also including the step of:

(d) in response to determining that the disk device is in freefall, triggering a disk drive protection operation.

9. The method of claim 8, wherein said triggering of the disk drive protection operation occurs with sufficient lead time to allow completion of the operation during freefall of the disk device over a distance as small as 10 cm.

10. The method of claim 1, wherein the disk device includes an accelerometer, and said method also includes the steps of:

operating the accelerometer to generate analog acceleration data; and

sampling the analog acceleration data to generate the acceleration data.

11. A disk device having a freefall detection subsystem configured to detect freefall of the disk device, said freefall detection subsystem including:

an accelerometer; and

a freefall detection processor coupled and configured to perform freefall detection by monitoring acceleration data indicative of acceleration of the disk device sensed by the accelerometer and determining in response to the acceleration data whether the disk device is in freefall, wherein the freefall detection processor is also configured to at least one other operation.

12. The disk device of claim 11, wherein said at least one other operation is decoding of encoded audio data.

13. The disk device of claim 11, also including a CPU coupled to the freefall detection processor.

14. A disk device having a freefall detection subsystem configured to detect freefall of the disk device, said freefall detection subsystem including:

an accelerometer; and

a freefall detection processor coupled and configured to perform freefall detection by monitoring data indicative of instantaneous acceleration of the disk device as sensed by the accelerometer and determining in response to the data whether the disk device is in freefall, including by

(a) determining from the data whether said instantaneous acceleration is less than gravitational acceleration during a first time interval of predetermined duration,

(b) determining from the data whether said instantaneous acceleration has a time derivative whose absolute magnitude exceeds a predetermined minimum value during a second time interval having a second predetermined duration; and

(c) determining that the disk device is in freefall by determining that said instantaneous acceleration is not less than gravitational acceleration during the first time interval and the absolute magnitude of the time derivative of said instantaneous acceleration does not exceed the predetermined minimum value during the second time interval.

15. The disk device of claim 14, wherein the predetermined minimum value of the time derivative of the instantaneous acceleration is at least substantially equal to zero.

16. The disk device of claim 14, wherein the data comprise samples generated during sample periods, the first time interval is a predetermined number of the most recent consecutive sample periods, and the second time interval is a second predetermined number of the most recent consecutive sample periods.

17. The disk device of claim 16, wherein the second time interval coincides with the first time interval.

18. The disk device of claim 14, wherein the second time interval coincides with the first time interval.

19. The disk device of claim 14, wherein one of the second time interval and the first time interval is a subinterval of but does not coincide with the other of said second time interval and said first time interval.

20. The disk device of claim 14, wherein the freefall detection processor is also configured to trigger performance by the disk device of a disk drive protection operation, in response to determining that the disk device is in freefall.

21. The disk device of claim 20, wherein the freefall detection processor is configured to trigger performance the disk drive protection operation with sufficient lead time to allow completion of said disk drive protection operation during freefall of the disk device over a distance as small as 10 cm.

22. The disk device of claim 14, wherein the freefall detection processor is also configured to at least one other operation.

23. The disk device of claim 22, wherein said at least one other operation is decoding of encoded audio data.

24. The disk device of claim 22, also including a CPU coupled to the freefall detection processor.

25. A portable device, including:

an accelerometer; and

a digital audio processing subsystem, coupled and configured to process digital audio data for playback, and to monitor data indicative of instantaneous acceleration of the portable device as sensed by the accelerometer to identify a rhythm associated with motion of the portable device.

26. The portable device of claim 25, wherein the digital audio processing subsystem is also configured to modify the playback in response to the rhythm identified by said digital audio processing subsystem.

27. The portable device of claim 25, wherein the digital audio processing subsystem is configured to perform at least one of speed up and slow down of said playback in response to the rhythm identified by said digital audio processing subsystem.

28. The portable device of claim 25, wherein the rhythm is a period and a phase of a periodic motion of the portable device.

29. A method for operating a portable device that includes at least one accelerometer, said method including the steps of:

(a) processing digital audio data for playback; and

(b) identifying a rhythm associated with motion of the device by processing acceleration data indicative of instantaneous acceleration of the device as sensed by the accelerometer.

30. The method of claim 29, also including the step of:

modifying the playback in response to the rhythm identified in step (b).

31. The method of claim 29, wherein step (b) includes the step of identifying a period and a phase of a periodic motion of the portable device.