Haptic actuator having a double-wound driving coil for temperature- and driving current-independent velocity sensing

Patent metadata

Field	Value
Publication number	US-11527946-B2
Application number	US-202016900718-A
Country	US
Kind code	B2
Filing date	Jun 12, 2020
Priority date	Jun 14, 2019
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

Abstract

A haptic engine includes a haptic actuator having a double-wound driving coil in which the two windings are connected with each other either in series or in parallel. By using the double-wound driving coil in which the two windings are connected with each other in series, an instant back EMF voltage induced in either of the two windings can be determined without having to measure in real time a resistance of the corresponding winding, and without having to sense a driving current through the double-wound driving coil. By using the double-wound driving coil in which the two windings are connected with each other in parallel, an instant back EMF voltage induced in either of the two windings can be determined without having to measure in real time a resistance of the corresponding winding.

First claim

What is claimed is:

1. A haptic engine comprising:
a frame;
a double-wound driving coil that is mechanically coupled with the frame and comprises a first coil and a second coil wound together around a common core and thermally coupled with each other, the first coil and the second coil being connected in series and having a common terminal, wherein a first ratio

N
=

R
1

R
2

 of resistances of the first coil and the second coil is different from a second ratio

M
=

N
1

N
2

 of a number of turns of the first coil and the second coil;
a driving source electrically coupled with the first coil at a first terminal different from the common terminal, and the second coil at a second terminal different from the common terminal to drive a driving current through the first coil and the second coil;
a first voltage sensor to sense a first driving voltage across the first coil when electrically coupled with the first coil at the first terminal and the common terminal;
a second voltage sensor to sense a second driving voltage across the second coil when electrically coupled with the second coil at the second terminal and the common terminal;
a mass supporting one or more permanent magnets, the mass arranged to be driven relative to the frame along a driving direction when the driving current is driven through the first coil and the second coil; and
computing circuitry configured to determine a velocity of the mass along the driving direction, the velocity determined
independently of resistances of either the first coil or the second coil, and the driving current through the first coil and the second coil, and
dependently of the first driving voltage over the first coil and the second driving voltage over the second coil, and the first and second ratios.

2. The haptic engine of claim 1 , wherein the first coil and the second coil have the same numbers of turns and different resistances.

3. The haptic engine of claim 2 , wherein
the first coil and the second coil have a same coil geometry, and are made from wire of a same material, and
the first coil has a first gauge, and the second coil has a second gauge different from the first gauge.

4. The haptic engine of claim 2 , wherein
the first coil and the second coil are made from wire of the same material, and have the same gauge, and
the first coil has a first coil geometry, and the second coil has a second coil geometry different from the first coil geometry.

5. The haptic engine of claim 2 , wherein
the first coil and the second coil have the same coil geometry and the same gauge, and
the first coil is made from a first material, and the second coil is made from a second material different from the first material.

6. The haptic engine of claim 1 , wherein to determine the velocity, the computing circuitry is configured to
compute a first back electromotive force (bEMF) induced in the first coil or a second bEMF induced in the second coil, wherein each of the first bEMF and the second bEMF is computed independently of resistances of either the first coil or the second coil, and the driving current through the first coil and the second coil, and dependently of the first driving voltage over the first coil, and the second driving voltage over the second coil, and the first and second ratios, and
take a third ratio of the first bEMF to a first motor constant associated with the first coil, or a fourth ratio of the second bEMf to a second motor constant associated with the second coil.

7. The haptic engine of claim 1 , wherein the driving source is configured to drive the driving current through the first coil and the second coil with frequencies in a frequency range of 10 Hz to 1 kHz, preferably 40 Hz to 300 Hz.

8. The haptic engine of claim 1 , comprising
an integrated circuit, wherein the integrated circuit comprises
driver circuitry comprising the driving source configured as a driving-current source to supply the driving current through the first coil and the second coil,
first sensing circuitry comprising the first voltage sensor, and
second sensing circuitry comprising the second voltage sensor.

9. The haptic engine of claim 8 , wherein the integrated circuit is disposed either inside or outside the frame.

10. The haptic engine of claim 8 , wherein the computing circuitry is coupled with
the first sensing circuitry to receive values of the first driving voltage across the first coil sensed by the first voltage sensor, and
the second sensing circuitry to receive values of the second driving voltage across the second coil sensed by the second voltage sensor.

11. The haptic engine of claim 1 , comprising
an integrated circuit comprising
driver circuitry comprising the driving source configured as a driving-voltage source to supply a driving voltage across the first coil and the second coil to induce the driving current through the first coil and the second coil.

12. The haptic engine of claim 11 , wherein
the driver circuitry comprises the first voltage sensor to sense the driving voltage across the first coil and the second coil when electrically coupled with the first coil and the second coil at the first terminal and the second terminal, and
the integrated circuit comprises sensing circuitry comprising the second voltage sensor to sense the second driving voltage across the second coil when electrically coupled with the second coil at the second terminal and the common terminal.

13. The haptic engine of claim 11 , wherein
the driver circuitry comprises the second voltage sensor to sense the driving voltage across the first coil and the second coil when electrically coupled with the first coil and the second coil at the first terminal and the second terminal, and
the integrated circuit comprises sensing circuitry comprising the first voltage sensor to sense the first driving voltage across the first coil when electrically coupled with the first coil at the first terminal and the common terminal.

14. The haptic engine of claim 1 , wherein the computing circuitry is disposed either inside or outside the frame.

15. A method for determining back electromagnetic force (bEMF) using a coil with two windings wound together around a common core, the two windings connected in series, wherein a first ratio

N
=

R
1

R
2

of resistances of a first of the two windings and second of the two windings is different from a second ratio

M
=

N
1

N
2

Assignees

• Apple Inc

Inventors

• Tarelli Riccardo
• Liu Yumeng
• Yoneoka Shingo

Classifications

• G01D5/2046

  by a movable ferromagnetic element, e.g. a core · CPC title

• H02K33/14

  wherein the alternate energisation and de-energisation of the two coil systems are effected or controlled by movement of the armatures · CPC title

• H02P6/182

  using back-emf in windings · CPC title

• H02P6/34

  Modelling or simulation for control purposes · CPC title

• H02K33/16 Primary

  with polarised armatures moving in alternate directions by reversal or energisation of a single coil system · CPC title