Abstract: An optical force sensor that may compensate for environmental effects, including, for example, variations in temperature of the device or the surroundings. In some examples, two force-sensitive layers are separated by a compliant layer. The relative electrical response of the two force-sensitive layers may be used to compute an estimate of the force of a touch that reduces the effect of variations in temperature. In some examples, piezoelectric films having anisotropic strain properties are used to reduce the effects of temperature.

Abstract: An optical force sensor, which may be used as input to an electronic device. The optical force sensor may be configured to compensate for variations in temperature using two or more force-sensitive components that are formed from materials having different temperature- and strain-dependent responses.

Abstract: A device configured to sense a touch on a surface of the device. The device includes a cover and a force-sensing structure disposed below the cover. The force-sensing structure may be positioned below a display and used in combination with other force-sensing elements to estimate the force of a touch on the cover of a device.

Abstract: Structures and methods are disclosed for an electronic device having an input surface that uses dual sensors to measure forces applied to the input surface. The forces can be estimated over a greater range of values than would be possible with either sensor alone. A second sensor can be used after a first sensor has reached a limit. A first sensor can be a strain sensor and a second sensor a pressure sensor. Both sensors may be resistance based, with signals from both sensors can be combined and measured by processing circuitry. Each sensor type may be part of planar arrays disposed beneath the input surface.

Abstract: Several techniques for driving a force sensor to reduce common mode offset are disclosed. The force sensor can include at least one set of individual strain sensitive structures formed on or in a surface of a substrate. Each set of individual strain sensitive structures can include one or more strain sensitive structures. At least one external resistor is operably connected in series between a first output of one or more transmitter channels and at least one set of strain sensitive structures. The external resistor(s) effectively increases the resistances of the strain sensitive structures to reduce the common mode offset. Additionally or alternatively, one or more signal generators may be connected to one or more transmitter channels. Each signal generator is configured to produce one or more signals that is/are designed to reduce common mode offset.

Abstract: A strain-responsive sensor incorporating a strain-sensitive element is disclosed. The strain-sensitive element includes a matched-pair of resistive structures disposed on opposite sides of a substrate. One resistive structure is coupled to a crossover, either a physical crossover or a soft crossover, such that current within the resistive structures of the matched pair flows in the same direction. In addition, one resistive structure of the matched pair has a different loop area than the other resistive structure.

Abstract: A force sensing device can be included in a display. Noise produced by various sources can be injected into the force signals produced by the force sensing device. Example noise sources include, but are not limited to, the display, Johnson or Thermal noise from the force sensing device, system noise, and magnetically-coupled or background noise produced by ambient light sources. A sampling scheme that includes one or more noise cancelling techniques can be employed to reduce the amount of noise in the force signals.

Abstract: A portable electronic device includes a cover glass, one or more strain gauges operable to indicate force exerted on the cover glass based on deformation of the cover glass, a housing that defines a sway space gap into which the cover glass deforms when the force is exerted on the cover glass, and an incompressible fluid positioned in the sway space gap. The incompressible fluid allows deformation of the cover glass into the sway space gap when the force is exerted on the cover glass and maintains a constant volume under hydrostatic pressure.

Abstract: A portable electronic device includes a cover glass, one or more strain gauges operable to indicate force exerted on the cover glass based on deformation of the cover glass, a housing that defines a sway space gap into which the cover glass deforms when the force is exerted on the cover glass, and an incompressible fluid positioned in the sway space gap. The incompressible fluid allows deformation of the cover glass into the sway space gap when the force is exerted on the cover glass and maintains a constant volume under hydrostatic pressure.

Abstract: A force sensor is disclosed. The force sensor includes a force-sensitive structure that compensates for temperature and other environmental changes through the use of a strain-sensitive element and one or more reference elements. An array of such force-sensitive structures forms a force-sensing layer.

Abstract: A strain-responsive sensor incorporating a strain-sensitive element is disclosed. The strain-sensitive element includes a matched-pair of resistive structures disposed on opposite sides of a substrate. One resistive structure is coupled to a crossover, either a physical crossover or a soft crossover, such that current within the resistive structures of the matched pair flows in the same direction. In addition, one resistive structure of the matched pair has a different loop area than the other resistive structure.

Abstract: Structures and methods are disclosed for an electronic device having an input surface that uses dual sensors to measure forces applied to the input surface. The forces can be estimated over a greater range of values than would be possible with either sensor alone. A second sensor can be used after a first sensor has reached a limit. A first sensor can be a strain sensor and a second sensor a pressure sensor. Both sensors may be resistance based, with signals from both sensors can be combined and measured by processing circuitry. Each sensor type may be part of planar arrays disposed beneath the input surface.

Abstract: One or more strain sensors can be included in an electronic device. Each strain sensor includes a strain sensitive element and one or more strain signal lines connected directly to the strain sensitive element. The strain sensor(s) are used to detect a force that is applied to the electronic device, to a component in the electronic device, and/or to an input region or surface of the electronic device. A strain sensitive element is formed or processed to have a first gauge factor and the strain signal line(s) is formed or processed to have a different second gauge factor. Additionally or alternatively, a strain sensitive element is formed or processed to have a first conductance and the strain signal line(s) is formed or processed to have a different second conductance.

Abstract: In an RFID system having at least one tag and at least one reader, a tag and a reader can, in one embodiment, use a pair of keys, known to both the tag and the reader, to restrict the interaction of the tag and the reader so that tags having the pair of keys interact only with readers that use the pair of keys.

Abstract: A strain-sensitive structure includes two resistive structures connected in series and formed on one surface of a substrate. One resistive structure is formed with a first trace arranged in first trace pattern. The other resistive structure is formed with a second trace arranged in a second trace pattern. The first resistive structure is configured to experience strain in response to an applied stress on the substrate. The second resistive structure is configured to experience less strain in response to the applied stress on the substrate compared to the first resistive structure. Together the strain-sensitive structure and the substrate form a force sensing layer that can be included in an electronic device.

Abstract: A device configured to sense a touch on a surface of the device. The device includes a cover and a force-sensing structure disposed below the cover. The force-sensing structure may be positioned below a display and used in combination with other force-sensing elements to estimate the force of a touch on the cover of a device.

Abstract: Disclosed herein is an electronic device having a force sensing device. The force sensing device receives a continuous force input which is translated into a discrete event. In order to more accurately determine the type of discrete event intended by a user, the electronic device is able to determine an amount of noise present in the electronic device and dynamically adjust force threshold values associated with the force sensing device.

Abstract: A device configured to sense a touch on a surface of the device. The device includes a cover and a force-sensing structure disposed below the cover. The force-sensing structure may be positioned below a display and used in combination with other force-sensing elements to estimate the force of a touch on the cover of a device.

Abstract: Systems and methods for accurately and precisely measuring the resistance of a resistive sensor of a matched resistive sensor pair disposed on opposite surfaces of a substrate. Certain embodiments include coupled each sensor of the matched resistive sensors to a thermally-isolated pair of reference resistors contained within an integrated circuit so as to form a Wheatstone bridge. A controller associated with the integrated circuit can adjust the resistance of the thermally-isolated pair of reference resistors until the ratio of resistances matches to the ratio of resistances between the sensors of the matched pair.

Abstract: A strain-responsive sensor incorporating a strain-sensitive element is disclosed. The strain-sensitive element includes a matched-pair of resistive structures disposed on opposite sides of a substrate. One resistive structure of the matched pair is coupled to a crossover, either a physical crossover or a soft crossover, such that current within the resistive structures of the matched pair flows in the same direction.