4Wire Resistive Touch Screen Working Principle:
The 4 Wire Resistive Touch Screen is a two-layer structure,
1. ITO glass substrate with one side uniform resistive ITO coating.
2. A very thick polyester ITO film which tightly suspended over the top of ITO glass substrate. This PET film has a hard, durable coating on the outer side, on inner side with ITO coating.
3. ITO glass and the ITO film are separated by printed small, transparent insulation spacer dots.
When the screen is touched, it pushes the ITO film to have an electrical contact with ITO glass (both on the ITO coating side). It produces a voltage which is the analog representation of the position touched.
In 4 Wire Resistive, the ITO glass (glass substrate) is set as Y axis, and ITO film as X axis. The microprocessor of controller applies +5V voltage to XL (X axis left) on the ITO film, and the voltage uniformly decreases to XR(X axis right) in zero voltage. In the same process, the microprocessor applies +5V voltage to YU (Y axis up) on the ITO glass, and the voltage uniformly decreases to YD (Y axis down) in zero voltage. When the screen is not touched, the controller detects the voltage on ITO glass / ITO film as zero voltage.
When the screen is touched, the voltage on the ITO film proportional to the X axis (horizontal) position of the touch point appears on the ITO glass. Next, the voltage on the ITO glass proportional to the Y axis (vertical) position of the touch point appears on the ITO film. These two voltages appearing on the ITO film and ITO glass are digitized by the A/D converter and then transmitted to the host.
The controller will receive all data to get the touched position according to the established calculating mode to figure out the exact X and Y coordinates
- Can be activated with any device
- Low cost solution
- Low power consumption
- Less durability compared to other technologies
- Less transmittance and overall optical quality
- Requires periodic recalibration