Force sensing circuitry

#The present disclosure relates to the field of force sensing circuits and systems.

#Traditional portable devices (e.g. mobile phones, tablet computers, remote controllers, video game controllers, etc.) typically include mechanical buttons for a user to control the portable device. Such mechanical buttons are susceptible to wear and tear and can be vulnerable to damage and malfunction due to ingress of water, dust and/or debris. As such, manufacturers are increasingly looking to alternative solutions to facilitate interaction between a user and a portable device.

#One approach to facilitating such interaction is to provide so called “virtual buttons” in the form of force sensors. A force sensor may be provided as part of a portable device in the place of a mechanical button. The force sensor may be configured to detect user interaction with the sensor (e.g. the sensor being touched or pressed) and to cause the portable device to initiate some functionality in response to the detected interaction. Such virtual buttons provide advantages over mechanical buttons, due to the absence of the moving parts of a mechanical button. This can lead to reduced wear and increased longevity of the portable device. The use of force sensors can also help to improve the water-resistance of a portable device, as mechanical buttons can provide a substantial entry point to fluids. Further, mechanical buttons are relatively large components of a portable device and therefore smaller alternatives such as force sensors can free up space for additional components. For example, in a mobile phone the additional space may be occupied by an increased number of 5G antennas.

#For a better understanding of examples of the present disclosure, and to show more clearly how the examples may be carried into effect, reference will now be made, by way of example only, to the following drawings in which:

#FIG. 1 illustrates an example of circuitry for biasing a force sensor;

#FIG. 2 illustrates another example of circuitry for biasing a force sensor;

#The description below sets forth example embodiments according to this disclosure. Further example embodiments and implementations will be apparent to those having ordinary skill in the art. Further, those having ordinary skill in the art will recognize that various equivalent techniques may be applied in lieu of, or in conjunction with, the embodiments discussed below, and all such equivalents should be deemed as being encompassed by the present disclosure.

#As noted above, force sensors present an alternative means for enabling interaction between a user and a device such as a portable device. A number of different types of force sensors have been developed in recent times. For example, resistive, inductive, capacitive, resistive-inductive-capacitive and piezo-electric force sensors have been explored as alternative means to enable user interaction. For any of these force sensors to be viable options to provide user interactivity, the force sensors should be configured so as to have an appropriate sensitivity, in use, to detect user interaction.

#FIG. 1 illustrates an example of circuitry 100 for biasing a force sensor 130. Circuitry 100 comprises power source (PS) 110 and bias generator module (BGM) 120. Power source 110 may comprise any suitable means for storing and supplying power such as a battery B110. Circuitry 100 may form part of a portable electronic device and as such components of the electronic device such as a touchscreen, speaker, microphone etc. may draw current (represented in FIG. 1 by I1) from the power source 110. The power source 110 will include some parasitic resistance, represented in FIG. 1 by resistance R110. However, it will be appreciated that R110 shown in power source 110 is for illustrative purposes and parasitic resistances that make up the “lumped resistance” R110 may exist throughout circuitry 100 and/or an electronic device incorporating circuitry 100.