S-TouchTM Capacitive Touch Controller PCB Layout Guide 5

The advantage of the touch-state slider is its simple design and high stability in noisy environments. However, if a large number of positions are required, this method becomes unfeasible due to the excessive need for sensor channels.

Another method involves using a proportional measurement slider. This approach does not rely on detecting the touch state on each sensing channel but instead determines the finger's position based on the exact capacitance changes measured by each sensor channel. After measuring the precise capacitance changes for each sensing channel, the finger's exact position is determined through proportional calculations.  diode,

Figure 7 Implementation of Proportional Measurement Slider

Finger touch in the aforementioned positions will cause an increase in capacitance for the three sensing channel electrodes. Due to variations in finger coverage area, the increment in capacitance for each sensor also differs. Subsequently, by processing the raw capacitance data of the sensors, the absolute position of the finger on the slider can be determined.  diode,

Touch Rotator

Similar to the slider, the touch rotator is also implemented based on touch state and proportional measurement methods.

The touch state-based rotator determines finger position by checking the status of each sensing channel. The proportional measurement-based rotator identifies finger position by measuring the exact capacitance increase in each sensing channel caused by finger contact. When a finger rolls over the rotator, it induces capacitance increases in multiple sensing channels. By calculating the capacitance increments of these channels, the precise finger contact location can be determined.

Figure 8 Implementation of Touch State and Proportional Measurement Touch Rotator  diode,

The stability of finger touch detection in a touch rotator depends on the required resolution and the number of sensing channels. For high-resolution touch rotators, more sensing channels may be necessary, rather than just the three used as shown in Figure 8.