Techniques for Providing a Haptic Output and Sensing a Haptic Input Using a Piezoelectric Body

• US 20190027674A1
• Filed: 07/18/2017
• Published: 01/24/2019
• Est. Priority Date: 07/18/2017
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zhang, Zhipeng, Koch, Richard H., Songatikamas, Teera
• Granted Patent: US 10,622,538 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 1/1643 the display being associated to a digitizer, e.g. laptops that can be used as penpads details related to the relative motion of the display enclosure with respect to the body enclosure, e.g. to move between laptop and tablet PC configuration G06F1/1615
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 3/016 Input arrangements with force or tactile feedback as computer generated output to the user
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/04886 by partitioning the display area of the touch-screen or the surface of the digitising tablet into independently controllable areas, e.g. virtual keyboards or menus
• CPC Class Codes: H10N 30/1071 with electrical and mechanical input and output, e.g. having combined actuator and sensor parts
• CPC Class Codes: H10N 30/20 with electrical input and mechanical output, e.g. functioning as actuators or vibrators
• CPC Class Codes: H10N 30/50 having a stacked or multilayer structure
• CPC Class Codes: H10N 30/802 Drive or control circuitry or methods for piezoelectric or electrostrictive devices not otherwise provided for
• CPC Class Codes: H10N 30/872 Connection electrodes of multilayer piezoelectric or electrostrictive devices, e.g. external electrodes

Abstract

Haptic interfaces are described. One haptic interface includes a piezoelectric body and first and second electrodes coupled to the piezoelectric body. The haptic interface also includes a control circuit. The control circuit includes a haptic actuator, a haptic sensor circuit, and an overcurrent protection circuit. The haptic actuator circuit is coupled to the first electrode and configured to charge the piezoelectric body. The charging causes the piezoelectric body to provide a haptic output. The haptic sensor circuit is coupled to the second electrode and configured to sense an electrical change at the second electrode. The electrical change is related to a haptic input received by the piezoelectric body. The overcurrent protection circuit is coupled to the second electrode and configured to limit a current flow into the haptic sensor circuit while the haptic actuator circuit is charging the piezoelectric body.

Claims

1. A haptic interface, comprising:

a piezoelectric body;

a first electrode coupled to the piezoelectric body;

a second electrode coupled to the piezoelectric body; and

a control circuit, comprising;

a haptic actuator circuit coupled to the first electrode and configured to charge the piezoelectric body, the charging causing the piezoelectric body to provide a haptic output;

a haptic sensor circuit coupled to the second electrode and configured to sense an electrical change at the second electrode, the electrical change related to a haptic input received by the piezoelectric body; and

an overcurrent protection circuit coupled to the second electrode and configured to limit a current flow into the haptic sensor circuit while the haptic actuator circuit is charging the piezoelectric body.

2. The haptic interface of claim 1, wherein the overcurrent protection circuit comprises:

a transistor coupled between the second electrode and a discharge node, the transistor having a control input configured to receive a signal that causes the transistor to open or close a current path between the second electrode and the discharge node.

3. The haptic interface of claim 1, wherein the overcurrent protection circuit comprises:

a clamper circuit coupled between the second electrode and a discharge node.

4. The haptic interface of claim 3, wherein the clamper circuit comprises a forward-biased diode coupled in parallel with a reverse-biased diode.

5. The haptic interface of claim 1, wherein the haptic sensor circuit comprises a sense amp, the sense amp comprising a negative input coupled to the second electrode and a positive input coupled to a discharge node.

6. The haptic interface of claim 5, wherein the overcurrent protection circuit is coupled between the negative input and the positive input of the sense amp, and the positive input of the sense amp is coupled to the discharge node.

7. The haptic interface of claim 5, wherein the overcurrent protection circuit comprises:

a transistor coupled between the negative input and the positive input of the sense amp, the transistor having a control input configured to receive a control signal that causes the transistor to open or close a current path between the negative input and the positive input of the sense amp,

wherein the positive input of the sense amp is further coupled to the discharge node.

8. The haptic interface of claim 7, wherein the haptic actuator circuit comprises:

a second transistor coupled between the first electrode and a power source, the second transistor having a second control input configured to receive a second control signal that causes the second transistor to open or close a second current path between the first electrode and the power source; and

a third transistor coupled between the first electrode and the discharge node, the transistor having a third control input configured to receive a third control signal that causes the third transistor to open or close a third current path between the first electrode and the discharge node.

9. The haptic interface of claim 5, wherein the overcurrent protection circuit comprises:

a charge integration capacitor coupled between the negative input of the sense amp and an output of the sense amp.

10. The haptic interface of claim 9, further comprising:

an integrated charge discharge circuit coupled to the charge integration capacitor, the integrated charge discharge circuit having a control input configured to receive a control signal that causes the integrated charge discharge circuit to discharge a charge integrated by the charge integration capacitor.

11. The haptic interface of claim 5, further comprising:

a digital sampling circuit coupled to an output of the sense amp.

12. A haptic interface, comprising:

a piezoelectric body;

a first electrode coupled to the piezoelectric body;

a second electrode coupled to the piezoelectric body; and

a control circuit, comprising;

a haptic actuator circuit coupled to the first electrode and configured to maintain a charge on the piezoelectric body, the charge causing the piezoelectric body to provide a haptic output; and

a haptic sensor circuit coupled to the second electrode and configured to sense an electrical change at the second electrode while the piezoelectric body is charged, the electrical change related to a haptic input received by the piezoelectric body.

13. A method of operating a haptic interface, comprising:

charging a piezoelectric body of the haptic interface to deliver a haptic output;

limiting a current flow into a haptic sensor circuit while charging the piezoelectric body; and

monitoring for a haptic input to the piezoelectric body using the haptic sensor circuit while the piezoelectric body is charged.

14. The method of claim 13, further comprising:

monitoring for the haptic input while charging the piezoelectric body.

15. The method of claim 13, wherein limiting the current flow into the haptic sensor circuit comprises:

diverting at least a portion of the current flow from into the haptic sensor circuit to a discharge node.

16. The method of claim 15, wherein diverting at least the portion of the current flow from into the haptic sensor circuit to the discharge node comprises:

applying a control signal to a transistor.

17. The method of claim 16, wherein the transistor is coupled between a first input and a second input of the haptic sensor circuit.

18. The method of claim 17, wherein the first input is coupled to an electrode attached to the piezoelectric body, and the second input is coupled to the discharge node.

19. The method of claim 15, wherein diverting at least the portion of the current flow from into the haptic sensor circuit to the discharge node comprises:

automatically diverting at least the portion of the current flow based on a parameter of a diode.

20. The method of claim 13, wherein limiting the current flow into the haptic sensor circuit comprises:

integrating a charge using a charge integrator coupled between an input of the haptic sensor circuit and an output of the haptic sensor circuit; and

clearing the integrated charge before monitoring for the haptic input.