What is the principle of a resistive touch screen?
- Aug 22, 2018 -
Nowadays, more and more electronic products have brought a lot of help to people's life. The resistive touch screen is a part used in electronic products. How does it work?Here's a look at it:
The contact screen contains two open layers superimposed on top and bottom. The four-line and eight-line contact screens consist of two layers of open resistance data with the same surface resistance. The five-line and seven-line contact screens consist of a resistive layer and a conductive layer.When pressure on the surface of a resistive touch screen, such as on the tip of a pen or finger, is large enough, contact between the top and the bottom of the screen can occur.All resistive touch screens use the voltage divider principle to act on the voltage representing X and Y coordinates. The voltage divider is made by connecting two resistors in series.The upper resistor (R1) is connected to the positive reference voltage (VREF) and the lower resistor (R2) is grounded.The voltage measurement at the junction of the two resistances is directly proportional to the resistance of the resistance below.To measure a coordinate in a specific direction on a resistive touch screen, bias a resistive layer: connect one side to the VREF and the other to the ground.At the same time, connect the unbiased layer to a high impedance input terminal of the ADC.When the pressure on the resistance touch screen is high enough to make contact between the two layers, the resistive surface is separated into two resistances.Their resistance is proportional to the distance from the contact point to the edge of the offset.The resistance between the contact point and the ground edge is the same as that under the divider.Thus, the measured voltage on the unbiased layer is proportional to the distance between the contact point and the ground edge.