TECHNICAL FIELD

Systems, methods and devices of the present disclosure relate, generally, to capacitive touch sensing, and more particularly, some embodiments relate to techniques for improved electromagnetic emissions control in touch sensors.

BACKGROUND

A typical touch interface system may incorporate touch sensors (e.g., capacitive sensors and/or resistive sensors, without limitation) that respond to an object in close proximity to, or physical contact with, a contact sensitive surface of a touch interface system. Such responses may be captured and interpreted to infer information about the contact, including a location of an object relative to the touch interface system.

Touchpads used with personal computers, including laptop computers and keyboards for tablets, often incorporate or operate in conjunction with a touch interface system. Displays often include touch screens that incorporate elements (typically at least a touch sensor) of a touch interface system to enable a user to interact with a graphical user interface (GUI) and/or computer applications. Examples of devices that incorporate a touch display include portable media players, televisions, smart phones, tablet computers, personal computers, and wearables such as smart watches, just to name a few. Further, control panels for automobiles, appliances (e.g., an oven, refrigerator or laundry machine) security systems, automatic teller machines (ATMs), residential environmental control systems, and industrial equipment may incorporate touch interface systems with displays and housings, including to enable buttons, sliders, wheels, and other touch elements.

While touch sensors emit electromagnetic emissions (EME), such as electromagnetic fields and electromagnetic radiation, traditionally, designers of touch sensors have been primarily concerned with minimizing a touch sensor's susceptibility to EME from nearby devices. Touch sensors were in the past used in environments where EME limits were very forgiving. However, limits apply to touch sensors based on their function and the environment in which they are installed. The inventors of this disclosure appreciate that to meet the strict EME limits of new applications for touch sensors such as automotive applications, techniques and systems are needed to test, calibrate, and operate touch sensors.

