Multiple pulse width modulation

• US 8,179,202 B2
• Filed: 02/16/2007
• Issued: 05/15/2012
• Est. Priority Date: 02/16/2007
• Status: Active Grant

• Current Assignee: Immersion Corporation
• Original Assignee: Immersion Corporation
• Inventors: Cruz-Hernandez, Juan Manuel, Grant, Danny A.
• Primary Examiner(s): Chang, Joseph
• Application Number:
  US11/675,967
• Publication Number:
  US 20080197901A1
• Time in Patent Office: 1,915 Days
• Field of Search: 332/109, 327/175, 345/156
• US Class Current: 332/109
• CPC Class Codes: H03K 3/017 Adjustment of width or dutycycle of pulses pulse width modulation H03K7/08 ; to maintain energy constant H03K3/015

Abstract

A method of generating a MPWM signal for a portable device such as a cellular telephone. For a first duty cycle that includes a MPWM frequency having N magnitude levels, the method generates a first waveform comprising a first and a second On pulse during a first MPWM frequency period. The first and second On pulses are separated by an Off period.

Claims

1. A method of generating a multiple pulse width modulation (MPWM) signal for a device, said method comprising:

generating at a single controller the MPWM signal that comprises at least one On pulse and at least one Off period and that has a number (N) of possible magnitude levels;

wherein the controller has a clock rate (C) and the MPWM signal comprises a plurality of MPWM periods, and each MPWM period is a square signal of a fixed time duration that is generated at a frequency (f), wherein the frequency (f) is directly based on the clock rate (C) of the controller and the number of possible magnitude levels (N) of the MPWM signal;

wherein the frequency (f) is N/C;

for at least one of magnitude level of the N magnitude levels, generating a first waveform comprising a first and a second On pulse during a first single MPWM period of the single controller;

wherein said first and second On pulses are separated by an Off period.

2. The method of claim 1, wherein said device is haptic enabled.

3. The method of claim 2, comprising:

for a second magnitude level, generating a second waveform during the first single MPWM period; and

for a third magnitude level, generating the first waveform during the first single MPWM period and generating the second waveform during a second single MPWM period, wherein said second single MPWM period directly follows the first single MPWM period.

4. The method of claim 3, comprising:

for the third magnitude level, generating the first waveform during a third single duty cycle, wherein said third single MPWM period directly follows the second single MPWM period.

5. The method of claim 4, wherein said MPWM signal comprises N×

2 magnitude levels.

6. A haptic enabled apparatus comprising:

a single controller for generating a multiple pulse width modulation (MPWM) signal;

wherein the MPWM signal comprises at least one On pulse and at least one Off period and has a number (N) of possible magnitude levels;

wherein the single controller has a clock rate (C) and the MPWM signal comprises a plurality of MPWM periods, and each MPWM period is a square signal of a fixed time duration that is generated at a frequency (f), wherein the frequency (f) is directly based on the clock rate (C) of the single controller and the number of possible magnitude levels (N) of the MPWM signal;

wherein the frequency (f) is N/C;

wherein said single controller is adapted to, for at least one of magnitude level of the N magnitude levels, generate a first waveform comprising a first and a second On pulse during a first single MPWM period of the single controller;

wherein said first and second On pulses are separated by an Off period.

7. The apparatus of claim 6, said MPWM generating a haptic signal.

8. The apparatus of claim 7, said controller further adapt to, for a second magnitude level, generate a second waveform during the first MPWM period;

and

for a third magnitude level, generating the first waveform during the first single duty cycle and generate the second waveform during a second single duty cycle, wherein said second single MPWM period directly follows the first single MPWM period.

9. The apparatus of claim 8, said controller further adapt to, for the third magnitude level, generate the first waveform during a third single MPWM period, wherein said third single MPWM period directly follows the second single MPWM period.

10. The apparatus of claim 9, wherein said MPWM signal comprises N×

2 magnitude levels.

11. The apparatus of claim 6, further comprising an actuator coupled to said controller, said actuator adapted to generate a vibration in response to the MPWM signal.

12. A computer readable medium having instructions stored thereon that, when executed by a processor, cause the processor to generate a multiple pulse width modulation (MPWM) signal for a device, said MPWM generating comprising:

generating at a single controller the MPWM signal that comprises at least one On pulse and at least one Off period and that has a number (N) of possible magnitude levels;

wherein the single controller has a clock rate (C) and the MPWM signal comprises a plurality of MPWM periods, and each MPWM period is a square signal of a fixed time duration that is generated at a frequency (f), wherein the frequency (f) is directly based on the clock rate (C) of the controller and the number of possible magnitude levels (N) of the MPWM signal;

wherein the frequency (f) is N/C;

for at least one of magnitude level of the N magnitude levels, generating a first waveform comprising a first and a second On pulse during a first single MPWM period of the single controller;

wherein said first and second On pulses are separated by an Off period.

13. The computer readable medium of claim 12, wherein said MPWM signal is a haptic signal.

14. The computer readable medium of claim 12, said MPWM generating comprising:

for a second magnitude level, generating a second waveform during the first single MPWM period; and

for a third magnitude level, generating the first waveform during the first MPWM period and generating the second waveform during a second single MPWM period, wherein said second MPWM period directly follows the first MPWM period.

15. The computer readable medium of claim 14, said MPWM generating comprising:

for the third magnitude level, generating the first waveform during a third MPWM period, wherein said third MPWM period directly follows the second MPWM period.

16. The method of claim 15, wherein said MPWM signal comprises N×

2 magnitude levels.

17. A single controller for generating a multiple pulse width modulation (MPWM) signal for a device, said single controller comprising:

means for generating at a controller the MPWM signal that comprises at least one On pulse and at least one Off period and that has a number (N) of possible magnitude levels;

wherein the single controller has a clock rate (C) and the MPWM signal comprises a plurality of MPWM periods, and each MPWM period is a square signal of a fixed time duration that is generated at a frequency (f), wherein the frequency (f) is directly based on the clock rate (C) of the controller and the number of possible magnitude levels (N) of the MPWM signal;

wherein the frequency (f) is N/C;

for at least one of magnitude level of the N magnitude levels, generating a first waveform comprising a first and a second On pulse during a first single MPWM period of the single controller;

wherein said first and second On pulses are separated by an Off period.

18. The controller of claim 17, wherein said MPWM signal is a haptic signal.

19. The controller of claim 18, further comprising:

for a second magnitude level, means for generating a second waveform during the first MPWM period; and

for a third magnitude level, means for generating the first waveform during the first single MPWM period and generating the second waveform during a second single MPWM period, wherein said second single duty cycle directly follows the first MPWM period.

20. The controller of claim 19 further comprising:

for the third magnitude level, means for generating the first waveform during a third MPWM period, wherein said third MPWM period directly follows the second single MPWM period.