Electronic device with noise-cancelling force sensor

• US 9,791,958 B2
• Filed: 01/10/2017
• Issued: 10/17/2017
• Est. Priority Date: 12/16/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Yang, Bingrui, Grunthaner, Martin P., Hotelling, Steven P.
• Primary Examiner(s): Bolotin, Dmitriy
• Application Number:
  US15/403,034
• Publication Number:
  US 20170147147A1
• Time in Patent Office: 280 Days
• CPC Class Codes: G01L 1/22 using resistance strain gauges
• CPC Class Codes: G01L 1/2262 involving simple electrical bridges
• CPC Class Codes: G06F 2203/04102 Flexible digitiser, i.e. constructional details for allowing the whole digitising part of a device to be flexed or rolled like a sheet of paper
• CPC Class Codes: G06F 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 3/0414 using force sensing means to determine a position
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: G06F 3/047 using sets of wires, e.g. crossed wires
• CPC Class Codes: H03K 17/9625 using a force resistance transducer
• CPC Class Codes: H04M 1/0266 for a display module assembly
• CPC Class Codes: H04M 1/72466 with selection means, e.g. keys, having functions defined by the mode or the status of the device
• CPC Class Codes: H04M 1/72469 for operating the device by selecting functions from two or more displayed items, e.g. menus or icons

Abstract

An electronic device may have a housing in which components such as a display are mounted. A strain gauge may be mounted on a layer of the display such as a cover layer or may be mounted on a portion of the housing or other support structure. The layer of material on which the strain gauge is mounted may be configured to flex in response to pressure applied by a finger of a user. The strain gauge may serve as a button for the electronic device or may form part of other input circuitry. A differential amplifier and analog-to-digital converter circuit may be used to gather and process strain gauge signals. The strain gauge may be formed form variable resistor structures that make up part of a bridge circuit that is coupled to the differential amplifier. The bridge circuit may be configured to reduce the impact of capacitively coupled noise.

Claims

1. An electronic device, comprising:

a display;

a display cover layer, wherein the display cover layer comprises first and second ends;

a strain gauge having first and second variable resistors formed on an interior surface of the display cover layer; and

a differential amplifier that receives signals from the first and second variable resistors, wherein the first and second variable resistors are located at the second end of the display cover layer, and wherein the first and second variable resistors are configured to serve as an input device for the electronic device.

2. The electronic device defined in claim 1, wherein the input device is a pressure-actuated input device.

3. The electronic device defined in claim 1, wherein the input device is an input device selected from the group consisting of:

a menu button, a volume button, a power button, a button with more than one function, a keyboard key, and a sliding input-output device.

4. The electronic device defined in claim 1, wherein the input device is an input device selected from the group consisting of:

a menu button, a volume button, a power button, and a button with more than one function.

5. The electronic device defined in claim 1, further comprising a speaker port located at the first end of the display cover layer.

6. The electronic device defined in claim 1, wherein the first and second variable resistors have different shapes.

7. The electronic device defined in claim 1, wherein the first and second variable resistors have different sizes.

8. The electronic device defined in claim 1, wherein the input device is sensitive to pressure from a user'"'"'s finger.

9. A cellular telephone, comprising:

a housing;

a display in the housing that forms a front face of the cellular telephone;

a speaker port formed on the front face of the cellular telephone;

a data port formed in the housing;

a display cover layer;

a strain gauge having first and second variable resistors formed on an interior surface of the display cover layer; and

a differential amplifier that receives signals from the first and second variable resistors, wherein the display cover layer has first and second opposing ends, wherein the first and second variable resistors are located at the second end of the display cover layer, and wherein the first and second variable resistors are configured to serve as an input device for the cellular telephone.

10. The cellular telephone defined in claim 9, wherein the input device is a pressure-actuated input device.

11. The cellular telephone defined in claim 9, wherein the input device is an input device selected from the group consisting of:

a menu button, a volume button, a power button, a button with more than one function, a keyboard key, and a sliding input-output device.

12. The cellular telephone defined in claim 9, wherein the input device is an input device selected from the group consisting of:

a menu button, a volume button, a power button, and a button with more than one function.

13. The cellular telephone defined in claim 9, wherein the first and second variable resistors are adjacent to each other on the display cover layer.