Is touch operation normal?

Today, touch-based user interfaces are commonplace, and everyone from children to the elderly can operate touch screens without any discomfort. It is no exaggeration to say that there is not a single day in which we do not touch mobile devices such as smartphones, kitchen appliances, public facilities such as banks and train stations, and commercial facilities such as hotels and department stores.

Here, we will introduce the basic algorithm of capacitive touch from among many touch interfaces.

Differences in user interface methods

First, let's talk about the types of user interfaces. The user interface can be broadly classified into panel type and button type. I think that it is often used in combination of the panel type and the button type. In addition, since it is selected from the viewpoint of product specifications and customer operability, it is not possible to judge the superiority or inferiority of any method.

Capacitive Touch Basic Algorithm

Of the user interface methods mentioned above, Microchip offers capacitive touch. A brief introduction to capacitive touch algorithms.

What is capacitive sensing?

The basic detection algorithm can be considered on the same principle as the parallel plate capacitor. First, capacitance C is expressed by the following formula.

Capacitive touch detects changes in capacitance, so various peripheral materials such as the thickness/distance of the overlay (cover material) used, the dielectric constant of the material used, the electrode area, and the dielectric constant of the PCB affected by

 

Capacitive touch detection method

There are two detection methods, self-capacitance and mutual-capacitance, and Microchip supports both methods.

 

~Self Cap~

Detects changes in capacitance that occur between electrodes and the human body

～Mutual Cap～

Detects touch by changing the state of the electric field between two electrodes

What did you think.

This time, we introduced the basic algorithm of capacitive touch from among the many touch interfaces.

 

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