Envelope modulator for haptic feedback devices

• US 8,102,364 B2
• Filed: 11/13/2006
• Issued: 01/24/2012
• Est. Priority Date: 08/02/2001
• Status: Active Grant

• Current Assignee: Immersion Corporation
• Original Assignee: Immersion Corporation
• Inventors: Tierling, Kollin M.
• Primary Examiner(s): Beck, Alexander S
• Assistant Examiner(s): Hicks, Charles V
• Application Number:
  US11/598,949
• Publication Number:
  US 20070057916A1
• Time in Patent Office: 1,898 Days
• Field of Search: 345156-163
• US Class Current: 345/156
• CPC Class Codes: G06F 3/016 Input arrangements with force or tactile feedback as computer generated output to the user
• CPC Class Codes: H03C 1/36 by means of semiconductor device having at least three electrodes H03C1/34, H03C1/50, H03C1/52, H03C1/62 take precedence

Abstract

An amplitude modulator circuit includes a reference oscillator and an envelope modulator coupled to the reference oscillator for receiving a reference signal. A microcontroller is coupled to the envelope modulator for providing an envelope signal to the envelope modulator and a low pass filter is coupled to the envelope modulator for receiving a modulated command from the envelope modulator. An inverter is coupled to the low pass filter for receiving a low passed envelope modulated signal from the low pass filter and a transducer or amplifier is coupled to the inverter and the low pass filter for receiving an inverted low passed signal and the low passed envelope modulated signal.

Claims

1. A circuit adapted to be coupled to an actuator having a resonant frequency, the circuit comprising:

a reference signal generator that generates a reference signal having a frequency substantially the same as the resonant frequency;

a processor that generates an envelope signal that includes haptic effects information;

a modulator coupled to the reference signal generator and the processor, wherein the modulator amplitude modulates the reference signal with the envelope signal to generate a modulated signal; and

a filter coupled to the modulator that removes high frequency content from the modulated signal to generate an output signal;

wherein the output signal, when applied as a drive signal to the actuator, causes the actuator to generate haptic effects based on the haptic effects information.

2. The circuit of claim 1, wherein the envelope signal is a pulse width modulated signal.

3. The circuit of claim 1, wherein the reference signal generator comprises an oscillator.

4. The circuit of claim 1, wherein the processor has a pulse width modulated frequency and the reference signal is a reference sinusoid with an instantaneous voltage;

wherein the modulated signal comprises a series of pulses at the pulse width modulated frequency with an amplitude that is proportional to the instantaneous voltage.

5. The circuit of claim 4, wherein the modulator is a ramp generator.

6. The circuit of claim 2, wherein the filter has a corner frequency between the resonant frequency and a pulse width modulation frequency of the envelope signal.

7. The circuit of claim 1, wherein the output signal is a differential drive signal.

8. The circuit of claim 1, further comprising an inverter coupled to the filter.

9. The circuit of claim 1, further comprising an amplifying driver coupled to the filter.

10. A method of generating a haptic effect, the method comprising:

generating a reference signal having a frequency substantially the same as a resonant frequency of an actuator;

generating an envelope signal that includes haptic effects information;

modulating the reference signal with the envelope signal to generate a modulated signal;

removing high frequency content from the modulated signal to generate an output signal;

applying the output signal as a drive signal to the actuator, causing the actuator to generate the haptic effects based on the haptic effects information.

11. The method of claim 10, wherein the envelope signal is a pulse width modulated signal.

12. The method of claim 10, wherein the reference signal generator is generated by an oscillator.

13. The method of claim 10, wherein the envelope signal is generated by a processor that has a pulse width modulated frequency and the reference signal is a reference sinusoid with an instantaneous voltage;

wherein the modulated signal comprises a series of pulses at the pulse width modulated frequency with an amplitude that is proportional to the instantaneous voltage.

14. The method of claim 10, wherein the output signal is a differential drive signal.

15. The method of claim 10, further comprising amplifying the output signal.

16. A modulator for a haptic feedback device that generates haptic effects with an actuator having a resonant frequency, the modulator comprising:

a first input for receiving from a reference signal generator a reference signal having a frequency substantially the same as the resonant frequency;

a second input for receiving from a processor an envelope signal that includes haptic effects information;

circuitry coupled to the first and second input for modulating the reference signal with the envelope signal to generate a modulated signal; and

an output coupled to a filter that removes high frequency content from the modulated signal to generate an output signal;

wherein the output signal, when applied as a drive signal to the actuator, causes the actuator to generate the haptic effects based on the haptic effects information.

17. The modulator of claim 16, wherein the envelope signal is a pulse width modulated signal.

18. The modulator of claim 16, wherein the reference signal generator comprises an oscillator.

19. The modulator of claim 16, wherein the processor has a pulse width modulated frequency and the reference signal is a reference sinusoid with an instantaneous voltage;

wherein the modulated signal comprises a series of pulses at the pulse width modulated frequency with an amplitude that is proportional to the instantaneous voltage.

20. The modulator of claim 16, wherein the modulator is a ramp generator.

21. The modulator of claim 16, wherein the output signal is a differential drive signal.