Touch Screen Overlay –The Differences Between Projected Capacitive and IR  

touch screen overlay

The useful lives of many ordinary monitor screens are being extended by a device called a touch screen overlay. Available in a choice of many different technologies, these devices are getting deployed in offices, showrooms, trade shows, information kiosks and even interactive advertising screens. Since it has gained relatively wide acceptance among users, the question as to which of the two most popular technologies is best for the touch screen overlay has come up.

So far, the two most popular technologies used on touch screen overlays are the infrared (IR) and projected capacitance (a.k.a. ProCap, or PCap). While touch screens utilizing these technologies are equally durable and reliable, there are some difference which may make one better than the other depending upon the application. So what are the features of each and their differences?

Projected capacitance technology is more commonly seen on smart phones and tablets; only recently have they been used on touch screen overlays. You can say projected capacitance technology has just recently joined the ‘big screen’ market. Research work undertaken by such organizations as the International Electronics Manufacturing Initiative may have had something to do with that.

This type of screens has two layers of conductors arranged in a grid, the layers separated by a thin and transparent insulator. The conductors are also made of transparent material, usually Indium Tin Oxide (ITO). When you touch the surface of the glass, the projected capacitance of the conductors at the point of contact is altered, allowing its location to be measured.

The advantages of projected capacitance touch screen overlays include:

  • High resistance to interference; even solid objects placed on top of the screen does not disrupt its function.
  • Capable of sensing multiple touches, as many as 40-60 at a time, and recognizes smooth gestures.
  • Very accurate and has a quick response time
  • Easy to maintain and is both dust and water resistant.
  • Will only respond to touch from a finger or stylus; rejects arm and palm touches.
  • Can be installed without a bezel or border (full glass surface)

There is only one major disadvantage: very large screen sizes are not widely available.

Infrared touch screen overlays are widely used in large screen formats. They are relatively inexpensive when compared to other technologies.

These screens use infrared light to sense touches on the surface. Bezels on each of the four sides contain matching infrared emitters and sensors to create an invisible grid of infrared beams. When the surface of the screen is touched, the infrared beam is broken at the point of contact which allows the device to determine its location.

Pros of infrared overlays are:

  • They are inexpensive and available in large sizes
  • They feature accurate touch sensing, fast response time and smooth gesture recognition
  • It is easy to make custom size screens

Cons include:

  • Solid objects placed on the screen creates blind spots
  • There always needs to be a bezel to house the IR components – it cannot be a borderless screen
  • Some old models are easily affected by bright light.

Which one is better for you? First you need to check out your requirements and the conditions under which you need the overlay to perform. After that it is just a matter of matching them with the features of each type of touch screen overlay.