Resonance driver for determining a resonant frequency of a haptic device

Patent metadata

Field	Value
Publication number	US-9355536-B2
Application number	US-201313930096-A
Country	US
Kind code	B2
Filing date	Jun 28, 2013
Priority date	Sep 27, 2012
Publication date	May 31, 2016
Grant date	May 31, 2016

Abstract

This document discusses, among other things, apparatus and methods for controlling a haptic transducer. In an example, a haptic controller can include an active termination driver having a configurable output impedance. The active termination driver can be configured to drive a haptic transducer and to process back electro-magnetic force (EMF) of the haptic transducer to provide motion feedback of the haptic transducer. In an example, the haptic controller can include a processor to provide a command signal to the active termination driver and to determine a resonant frequency of the haptic device using the motion feedback of the haptic transducer.

First claim

What is claimed is:

1. A haptic controller comprising:
an active termination driver having a configurable output impedance, the active termination driver configured to drive a haptic transducer and to process back electro-magnetic force (EMF) of the haptic transducer to provide motion feedback of the haptic transducer;
a processor to provide a command signal to the active termination driver and to determine a resonant frequency of the haptic device using the motion feedback of the haptic transducer;
a peak detector configured to detect at least one of a minimum peak or a maximum peak of the back EMF: and
a zero-crossing detector configured to provide timing information to the processor relative to the back EMF crossing a voltage value approximately halfway between the minimum peak and the maximum peak of the back EMF.

2. The haptic controller of claim 1 , wherein the active termination driver includes an active element configured to provide the configurable output impedance.

3. The haptic controller of claim 2 , wherein the active element includes a negative impedance converter.

4. The haptic controller of claim 3 , wherein the negative pedance converter is configured to provide an amplified voltage indicative of the back EMF.

5. The haptic controller of claim 4 , wherein the negative impedance converter is configured to receive a digital output from the processor and to provide a negative impedance based on the digital output.

6. The haptic controller of claim 1 , wherein the processor is configured to adjust a braking rate of the haptic transducer using a negative impedance converter.

7. A method comprising:
receiving a command signal at an active termination driver from a processor; driving a haptic transducer using the active termination driver and the command signal;
processing back EMF of the haptic transducer using the active termination driver to provide motion feedback of the haptic transducer; and
determining a resonant frequency of the haptic transducer using the motion feedback of the haptic transducer;
wherein the determining a resonant frequency of the haptic transducer includes detecting a period of the resonant frequency using the motion feedback of the haptic transducer; and
wherein the detecting a period includes;
detecting a maximum peak of the back EMF using a peak detector;
detecting a minimum peak of the back EMF using the peak detector; and
detecting two sequential crossings of the back EMF of a value halfway between the minimum peak and the maximum peak using a zero-crossing detector.

8. The method of claim 7 , wherein processing the back EMF includes amplifying the back EMF of the haptic transducer to provide the motion feedback using a negative impedance converter.

9. The method of claim 8 , including braking resonant otion of the haptic transducer using the negative impedance converter.

10. The method of claim 9 , wherein braking the resonant motion includes receiving a impedance information from the processor at the negative impedance converter; and
adjusting a negative impedance of the negative impedance converter using the impedance information.

11. The method of claim 10 , wherein the impedance information includes digital impedance information.

12. The method of claim 7 , wherein detecting a period includes driving an output of the active termination driver to predetermined value; and
detecting two sequential zero crossings of the back EMF using a zero-crossing detector.

13. A system comprising:
a resonant haptic transducer; and
haptic controller configured to couple to the resonant haptic transducer, the haptic controller including:
an active termination driver configured to drive a haptic transducer and to process back electro-magnetic force (EMF) to provide motion feedback of the haptic transducer;
a processor to provide a command signal to the active termination driver and to determine a resonant frequency of the haptic device using the motion feedback of the haptic transducer
a peak detector configured to detect at least one of a minimum peak or a maximum peak of the back EMF; and
a zero-crossing detector configured to provide timing information to the processor relative to the back EMF crossing a voltage value approximately halfway between the minimum peak and the maximum peak of the back EMF.

14. The haptic controller of claim 13 , wherein the active termination driver includes a negative impedance converter.

15. The haptic controller of claim 14 , wherein the negative impedance converter is configured to provide an amplified voltage indicative of the back EMF.

16. The haptic controller of claim 14 , wherein the negative impedance converter is configured to receive a digital output from the processor and to provide a negative impedance based on a value of the digital output.

17. Wreviously Presented) The haptic controller of claim 13 , wherein the processor is configured to adjust a braking rate of the haptic transducer using a negative impedance converter.

Assignees

• Fairchild Semiconductor

Inventors

• Crawley Philip J
• Shushtarian Majid

Classifications

• B06B1/0246

  with a feedback signal · CPC title

• G08B6/00 Primary

  Tactile signalling systems, e.g. tactile personal calling systems · CPC title