Capacitive touchscreens are seemingly ubiquitous, appearing in more and more products, from cars and kitchen appliances to kids' toys. Companies must meet or exceed the industry standard to stay competitive. In the touchscreen industry, this amounts to a capacitive touchscreen that is equally or more accurate and precise as touchscreens in competing devices. In practice, a full characterization of electrical and thermal effects is necessary to ensure proper functioning of a touchscreen device. Let's quickly review the physics behind a capacitive touchscreen.
The underlying principle of capacitive touchscreens is capacitance, or the amount of energy that can be stored in the electric field between two conductive objects. A capacitor consists of two parallel metal plates with a dielectric material between them. Bringing a dielectric material between two conductive objects or changing the distance between the plates alters the capacitance between them. A capacitive touchscreen has a large number of electrode pairs, each with a capacitance-to-finger location curve that precisely maps the finger location.
Design engineers consider factors ranging from number of electrodes necessary for accuracy, to finger moisture and how hard the screen is pressed. As there is more than one physical effect to consider and fast development is key, multiphysics simulation software is an indispensable tool in the design of these devices.
With COMSOL Multiphysics® software and computational apps the full characterization of physical effects and complete optimization of performance is streamlined. First the engineer sets up the simulation within the Model Builder of COMSOL Multiphysics®. Then, with the Application Builder, it is straightforward to convert the mathematical model into an easy-to-use app. The app designer has full control over which parts of the simulation will be shared and modifiable by the app user.
The computational app is much simpler to interact with than the underlying multiphysics model. As such, the crucial insight derived from the full simulation can be easily shared with a larger team by way of the app, speeding overall product development. Continue reading to learn how to build a custom app for a touchscreen device within COMSOL.
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