# US 11,442,544 B2 · Force transducer for electronic devices

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- Number: US 11,442,544 B2
- Document ID: US11442544B2
- Status: Granted
- Kind: B2
- Application number: 15/949,968
- Filed: 2018-04-10
- Published: 2018-11-01
- Granted: 2022-09-13
- Earliest claimed: 2017-05-01
- Assignees: Apple Inc.
- Applicants: Apple Inc.
- Inventors: Joseph C. Doll; Pavan O. Gupta; Teera Songatikamas; Adam J. Monkowski
- Web page: https://patentgrep.com/patent/US11442544B2

## CPC

- G06F 3/016: {Input arrangements with force or tactile feedback as computer generated output to the user}
- G06F 1/1626: {with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]}
- G06F 1/1637: {Details related to the display arrangement, including those related to the mounting of the display in the housing}
- 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)}
- G06F 3/041: Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F 3/0412: {Digitisers structurally integrated in a display}
- G06F 3/0416: {Control or interface arrangements specially adapted for digitisers}
- G06F 3/044: by capacitive means
- H10N 30/101: {with electrical and mechanical input and output, e.g. having combined actuator and sensor parts}
- H10N 30/802: {Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits}
- H10N 30/8536: {Alkaline earth metal based oxides, e.g. barium titanates}
- H10N 30/8542: {Alkali metal based oxides, e.g. lithium, sodium or potassium niobates}
- H10N 30/87: Electrodes or interconnections, e.g. leads or terminals
- H10N 39/00: Integrated devices, or assemblies of multiple devices, comprising at least one piezoelectric, electrostrictive or magnetostrictive element covered by groups H10N30/00 – H10N35/00
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A force transducer for an electronic device can be operated in a drive mode and a sense mode simultaneously. In particular, the force transducer can provide haptic output while simultaneously receiving force input from a user. The force transducer is primarily defined by a monolithic piezoelectric body, a ground electrode, a drive electrode, and a sense electrode. The ground electrode and the drive electrode each include multiple electrically-electrically conductive sheets that extend into the monolithic body; the electrically conductive sheets of the ground electrode and the drive electrode are interdigitally engaged. The sense electrode of the force transducer is typically disposed on an exterior surface of the monolithic body.

## Claims

### Claim 1

A force transducer comprising:
a ground electrode comprising a first plurality of sheets;
a drive electrode comprising a second plurality of sheets, interdigitally aligned with the first plurality of sheets;
a monolithic body separating the first plurality of sheets from the second plurality of sheets and comprising an upper surface; and
a sense electrode array comprising at least two discrete sense electrodes disposed on the upper surface of the monolithic body.

### Claim 2 (depends on 1)

The force transducer of claim 1, wherein:
the first plurality of sheets comprises an upper sheet; and
the upper sheet is below the upper surface of the monolithic body.

### Claim 3 (depends on 1)

The force transducer of claim 1, wherein the monolithic body is formed from a piezoelectric material.

### Claim 4 (depends on 3)

The force transducer of claim 3, wherein the piezoelectric material comprises barium titanate.

### Claim 5 (depends on 1)

The force transducer of claim 1, wherein the sense electrode array is arranged in a row on the upper surface of the monolithic body.

### Claim 6 (depends on 1)

The force transducer of claim 1, wherein:
the ground electrode is coupled to the sense electrode array via a sense circuit; and
the ground electrode is coupled to the drive electrode via a drive circuit.

### Claim 7 (depends on 1)

The force transducer of claim 1, wherein:
the first plurality of sheets comprises a first number of sheets and the second plurality of sheets comprises a second number of sheets; and
the first number is different from the second number.

### Claim 8

An electronic device comprising:
a housing;
a display within the housing;
a multimode force interface configured to provide force output and to receive force input, the multimode force interface positioned below the display and comprising:
an interdigitated force transducer comprising:
a drive electrode defined by a first set of electrically-conductive sheets extending into a monolithic body;
a ground electrode defined by a second set of electrically-conductive sheets interdigitally aligned with the first set of electrically-conductive sheets; and
an array of sense electrodes coupled to an outer surface of the monolithic body, the outer surface of the monolithic body coupled to an interior surface of the display and aligned with an active display region of the display; and
a controller coupled to the interdigitated force transducer; wherein
the controller is configured to operate the interdigitated force transducer in a drive mode to provide force output and a sense mode to receive force input.

### Claim 9 (depends on 8)

The electronic device of claim 8, wherein, in the drive mode, the controller applies a drive signal to the interdigitated force transducer and, in response, the interdigitated force transducer generates a haptic output through the display.

### Claim 10 (depends on 9)

The electronic device of claim 9, wherein:
the interdigitated force transducer is a first interdigitated force transducer; and
the multimode force interface comprises an array of interdigitated force transducers comprising the first interdigitated force transducer.

### Claim 11 (depends on 10)

The electronic device of claim 10, wherein the array of interdigitated force transducers are arranged in a grid.

### Claim 12 (depends on 8)

The electronic device of claim 8, wherein, in the sense mode, the controller receives a sense signal from the interdigitated force transducer that corresponds to a force input applied by a user to the display.

### Claim 13 (depends on 8)

The electronic device of claim 8, wherein: the monolithic body comprises a piezoelectric material.

### Claim 14 (depends on 8)

The electronic device of claim 8, wherein the array of sense electrodes are parallel to one of the electrically conductive sheets of the ground electrode.

### Claim 15

A method of operating a multimode force interface comprising:
providing a drive signal to a drive electrode of a force transducer, the drive electrode defined by a first set of electrically-conductive sheets extending into a monolithic body and interdigitally aligned with a second set of electrically-conductive sheets extending into the monolithic body and defining a ground electrode;
obtaining a sense signal from a sense electrode selected from an array of sense electrodes defined on an external surface of the force transducer; and
filtering the sense signal based on the drive signal.

### Claim 16 (depends on 15)

The method of claim 15, wherein filtering the sense signal comprises reducing an amplitude of the sense signal.

### Claim 17 (depends on 15)

The method of claim 15, wherein filtering the sense signal comprises applying a low-pass filter to the sense signal.

### Claim 18 (depends on 15)

The method of claim 15, wherein the drive signal is a higher frequency signal than the sense signal.

### Claim 19 (depends on 15)

The method of claim 15, wherein the drive signal is associated with a selected haptic output.

### Claim 20 (depends on 19)

The method of claim 19, wherein the selected haptic output is a click.