Resistive touch screens consist of a glass overlay formed to fit the size and curvature of a monitor's display face. A transparent thin metallic conductive coating is bonded on the external surface of the glass overlay (touch screen). The glass overlay is then covered with a clear, hard coated sheet of plastic, which is also conductivity coated, on the underside. This cover sheet is suspended over the glass by tiny separator dots, each less than one-thousandth of an inch thick. Very low level currents (different for the upper and glass overlay conductive coatings) are passed through the conductive coatings. When the user touches the screen, the conductive inner surface of the plastic sheet makes contact with the conductive coating on the top surface of the glass. The controller senses the contact and instantly computes the X and Y coordinate information.

Capacitive touch screens use a glass overlay formed to fit the size and curvature of a monitor's display face. A transparent thin metallic conductive coating is bonded on the external surface of the glass overlay (touch screen) and a very low-level current is passed through the conductive coating. As the screen is touched, the finger acts as a capacitor, drawing current from the four corners of the screen. The controller measures the current drop and calculates the touch coordinates on the X and Y-axes.

A surface acoustic wave touch screen consists of a clear glass overlay. Each axis on the overlay has a transmitting and receiving piezoelectric transducer, and a set of reflective strips which function as wave guides to send and receive the sound waves sent across the glass overlay. The touch screen controller sends a 5MHz burst to the transmitting transducers which convert the signal into surface acoustic waves. These waves propagate across the surface of the glass. When a finger touches the touch screen surface, a portion of the wave is absorbed. The resultant change in the received signal is analyzed by the controller and digitized into X and Y coordinates. Z-axis functionality is also available.

Scanning infrared (IR) touch panels rely on the interruption of an IR light grid in front of the display screen. The touch frame contains a row of IR light-emitting diodes (LED's) and phototransistors, each mounted on opposite sides of the bezel to create a grid of invisible infrared light. When a stylus, such as a finger, enters the grid, it obstructs the beams. The phototransistors detect the absence of light and transmit a signal that identifies the X and Y coordinates.

3M Dispersive Signal Technology (DST) is poised to become the touch technology standard for large-screen interactive displays. Where traditional touch technologies detect "touch" by interrupting acoustic waves, optical fields or infrared beams above the surface of the touch screen, DST precisely calculates touch locations by analyzing the bending waves — created by the user’s touch — within the glass substrate. This unique approach provides fast, accurate, reliable touch performance and operation unaffected by contaminants, scratches, or static objects on the screen. Also, Micro Touch DST supports hand, glove and stylus input and multi-user capability.

TSI Touch LLC. provides quality touch interactive hardware to support the Digital Signage market in multiple environments including malls, churches, hotels, convention centers, restaurants, schools, universities, hospitals, financial institutions, corporate offices, medical facilities, airports and mass transit stations. TSI Touch's touch screen monitors are designed to provide innovative, affordable solutions that can withstand the harshest of environments.
 

Learn more about DST by watching the Demo Video

Learn more about DST by watching the Impact Video