Electronics with Noise Cancelling Force Sensors

Abstract

The present invention relates to electronic equipment with noise canceling force sensors. An electronic device may have a housing in which components such as a display are mounted. Strain gauges may be mounted on a layer of the display, such as an overlay, and may be mounted on a portion of the housing or other support structure. The layer of material on which the strain gauges are mounted may be configured to bend in response to pressure applied by a user's finger. Strain gauges can be used as buttons for electronic devices, or can form part of other input circuits. Differential amplifiers and analog-to-digital converters can be used to collect and process strain gauge signals. The strain gauge may be formed from a variable resistor structure forming part of a bridge circuit coupled to a differential amplifier. The bridge circuit may be configured to reduce the effects of capacitively coupled noise.

Description

technical field

[0001] This application relates to electronic devices and, in particular, to electronic devices having strain gauges. Background technique

[0002] Strain gauges can be used as part of the input device to gather user input. System noise, such as capacitively coupled noise from the user's body, can degrade the performance of the strain gauge if care is not taken. Improper handling of strain gauges can produce erroneous strain gauge measurements.

[0003] Accordingly, it would be desirable to be able to provide improved strain gauges for use in electronic devices. Contents of the invention

[0004] An electronic device may have a housing in which components such as a display are mounted. The display can be covered by a display cover. The display cover layer may be formed from glass, plastic, or other transparent materials.

[0005] The strain gauges may be mounted on the display cover, on a portion of the housing, or on other support structures within th...

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