Touch Screen Technologies
Touch Screen Technologies
Resistive Touch Screen Technology

Resistive touch screens have a flexible top layer and a rigid bottom layer separated by insulating dots, with the inside surface of each layer coated with a transparent conductive coating.

Voltage applied to the layers produces a gradient across each layer. Pressing the flexible top sheet creates electrical contact between the resistive layers, essentially closing a switch in the circuit.


  • Value solution
  • Activated by any stylus
  • High touch point resolution
  • Low power requirements


  • Reduced optical clarity
  • Polyester surface can be damaged

Projected Capacitive (Multi-touch) Technology

Projected capacitive technologies detect touch by measuring the capacitance at each addressable electrode. When a finger or a conductive stylus approaches an electrode, it disturbs the electromagnetic field and alters the capacitance. This change in capacitance can be measured by the electronics and then converted into X,Y locations that the system can use to detect touch.

3M Project Capacitive Technology (3M PCT) is based on mutual capacitance to create multi-touch interactive. Mutual capacitance is the intentional or unintentional capacitance between two "charge holding objectsā€¯ (see illustration). Projected capacitance touchscreens intentionally create mutual capacitance between elements of columns and rows in the vicinity where each intersect the other. This allows the system electronics to measure each node (intersection) individually to detect multiple touches on the screen during one screen scan.

When a finger touches near an intersection, some of the mutual capacitance between the row and column is coupled to the finger which reduce the capacitance at the intersection as measured by the system electronics. This reduced capacitance crosses the "touch threshold" set by the electronics indicating a touch has occurred.


  • Extremely durable
  • Very accurate
  • Good optical clarity
  • Good resolution


  • Requires bare finger or capacitive stylus
  • Severe scratch can affect operation within the damaged area

Dispersive (DST) Touch Screen Technology

The DST Touch System determines the touch position by pinpointing the source of "bending waves" created by finger or stylus contact within the glass substrate. This process of interpreting bending waves within the glass substrate helps eliminate traditional performance issues related to on-screen contaminants and surface damage, and provides fast, accurate touch attributes.


  • Fast, accurate repeatable touch
  • Touch operates with static objects or other touches on the screen
  • Touch unaffected by surface contaminants, such as dirt, dust and grime
  • Excellent light transmission provides vibrant optical characteristics with anti-glare properties
  • Operation unaffected by surface damage
  • Input flexibility from finger or stylus, such as pencil, credit card, fingernail, or almost any pointing stylus
  • Available for display sizes 32" to 46"


  • More expensive to integrate than Optical
  • Only available for displays 32" and larger

Acoustic Wave Touch Screen Technology (SAW)

Acoustic wave touch screens use transducers mounted at the edge of a glass overlay to emit ultrasonic sound waves along two sides. These waves are reflected across the surface of the glass and received by sensors. A finger or other soft tipped stylus absorbs some of the acoustic energy and the controller measures the amplitude change of the wave to determine touch location.


  • Good optical clarity
  • Z-axis capability
  • Durable glass front


  • Requires finger or sound absorbing stylus
  • Difficult to industrialize
  • Signal affected by surface liquids or other contaminants

Infrared Touch Screen Technology

Infrared touch screens are based on light-beam interruption technology. Instead of an overlay on the surface, a frame surrounds the display. The frame has light sources, or light emitting diodes (LEDs) on one side and light detectors on the opposite side, creating an optical grid across the screen.

When an object touches the screen, the invisible light beam is interrupted, causing a drop in the signal received by the photo sensors.


  • 100% light transmission (not an overlay)
  • Accurate


  • Costly
  • Low reliability (MTBF for diodes)
  • Parallax problems
  • Accidental activation
  • Low touch resolution
  • No protection for display surface

Optical Touch Screen Technology

Optical touch screen technology uses two line scanning cameras located at the corners of the screen. The cameras track the movement of any object close to the surface by detecting the interruption of an infra-red light source. The light is emitted in a plane across the surface of the screen and can be either active (infra-red LED) or passive (special reflective surfaces).


  • 100% light transmission (not an overlay)
  • Accurate
  • Can be retro-fitted to any existing large format LCD or Plasma display
  • Can be used with finger, gloved hand or stylus
  • Requires only one calibration
  • Plug and play - no software drivers


  • Can be affected by direct sunlight
  • Frame increases overall depth of monitor
  • Cannot be fitted to plasma and LCD displays with integrated speakers

However, there are now several different types of multi-touch, depending on the touch technology employed. Below is an explanation of the different types of touch available which also acts as a guide for the terms we use for describing the touch screens we supply.
Single Touch

Single Touch occurs when a finger or stylus creates a touch event on the surface of a touch sensor or within a touch field so it is detected by the touch controller and the application can determine the X,Y coordinates of the touch event.

These technologies have been integrated into millions of devices and typically do not have the ability to detect or resolve more than a single touch point at a time as part of their standard configuration.

Single Touch with Pen Input

Inactive pens enable the same input characteristics as a finger, but with greater pointing accuracy, while sophisticated, active pens can provide more control and uses for the touch system with drawing and palm rejection capabilities, and mouse event capabilities.

Single Touch with Gesture

Since single touch systems can´t resolve the exact location of the second touch event, they rely on algorithms to interpret or anticipate the intended gesture event input. Common industry terms for this functionality are two-finger gestures, dual touch, dual control, and gesture touch.

Two Touch (2-point)

The best demonstration of Two Touch capability is to draw two parallel lines on the screen at the same time. Two Touch systems can also support gesturing.


Multi-touch is considered by many to become a widely-used interface mainly because of the speed, efficiency and intuitiveness of the technology.

To take full advantage of the multi-touch capabilities of this device, you can download multi-touch development applications from the following software companies:
Touchtech Lima
Touchtech Lima is a premium multi-touch software solution. It is designed for multi-touch table and wall displays to create interactive presentations using your existing files (pictures, videos, and documents etc).
NUITEQ´s multi-touch software product Snowflake Suite is a premium multi-touch software solution. It is designed for multi-touch table and wall displays to create interactive presentations using your existing files (pictures, videos, and documents etc).
MultiTouch pack from Aduma is all about engaging touch presentations. It is used across a variety of markets whenever there is a need to captivate and engage an audience.
Omnitapps Multi Touch Suite
Omnitapps Multi Touch Suite is the fully customizable (multi) touch application suite. It offers a collection of applications that offers you a unique way to present your products or services.