Resistive Touch screens

...response to pressure

If you are in search of a simple, reliable, and affordable screen input technology, then the resistive technology is the right choice. Although this technique is not new to the market, among a few others it is still popular in the industry. In harsh environments where gloves are often used or in places with high exposure to EMI (electromagnetic interference), this form of input system is still preferred. For preferred data input using a stylus, a resistive control element also the better solution.

For applications where haptic feedback is required, it is possible to maintain an inexpensive input solution by integrating a resistive touch screen into a membrane keyboard.

How does it works?

Resistive touch screens respond to pressure. With this principle, two electrically conductive layers are located at a small distance from each other, one above the other. In order to prevent these from touching when not operated, they are separated by a spacer – so-called spacer dots. These spacers are so small that they are visible only upon close inspection.

On these two layers, a DC voltage (direct current voltage) is then applied alternately and crosswise. When the screen is touched, the conductive layers connect at the point of pressure, therefore forming a voltage divider. At this voltage divider, the electrical resistance can now be measured and the position of the pressure points can be localized.

Pros and cons

Pros

  • Operation is possible even when wearing heavy work gloves
  • Precise control is possible when using a stylus
  • Due to the mechanical activation of these systems, they are much less susceptible to electromagnetic interference

Cons

  • With conventional resistive systems, only single-touch operation is possible
  • Gesture control is very limited
  • Wear due to the mechanical stress during operation
  • Sensitive surface - not suitable for devices vulnerable to vandalism

Applications

Due to the simple design, the usability with a stylus and gloves, the high electrical reliability and low cost, the resistive technology is still widely used. Among others, it is used in:

  • Industrial-PCs
  • Office equipment (e.g. photocopiers)
  • Household appliances (e.g. coffee makers)
  • Hand control devices (e.g. car diagnostic)
  • Input devices in medical technology

As controls in these application areas hardly have to master complex gestures and multi-touch operations, the advantages of resistive technology commonly outweigh the disadvantages.