Dispersive Signal Touch Screen TechnologyDispersive Signal Touch Technology, specifically developed for interactive digital signage applications, sets new large-format touch standards for fast, accurate repeatable touch response. In addition, Dispersive Signal Technology’s operation is unaffected by contaminants, static objects or other touches on the touch screen. Other key characteristics of this patented technology are exceptional optics, ease of integration, and input flexibility. Dispersive Signal Technology (DST) consists of a chemically-strengthened glass substrate with piezos mounted on each corner, mated to a sophisticated, dedicated controller.

How Dispersive Signal Technology Works

Dispersive Signal Technology determines a “touch point” by measuring the mechanical energy (bending waves) within a substrate created by a finger or stylus touching the surface of the glass. Bending waves differ from surface waves in that they traverse through the thickness of the panel rather than the surface of the material, which provides several important advantages including enhanced palm rejection and superior scratch resistance. When the touch implement impacts the screen, bending waves are induced that radiate away from the touch location. As the wave travels outwards, the signal spreads out over time due to the phenomena of dispersion (explained below). Piezoelectric sensors positioned in the corners on the backside of the glass convert this smeared mechanical impulse into an electrical signal. The distance from each sensor determines the extent to which the signal is dispersed. Namely, the further away the “touch point” is from the sensor, the more the signal is smeared.

Dispersion Explained

Dispersion is the phenomenon that the velocity of a bending wave propagating through solid material is dependent upon that wave’s frequency. An impulse caused by a touch contact generates a number of bending waves within the substrate, all at different frequencies. Because of “dispersion”, these bending waves propagate out to the edges of the glass at different speeds rather than in a unified wave front. The piezo sensors at the corners sense the high frequency waves first and the lower frequency waves second, so what the sensors ultimately receive is a wave formation that doesn’t resemble original pulse. This “smearing effect” is compounded by the reflections off the internal surfaces of the glass substrate. The net result is a seemingly chaotic mass of waves all interfering with one another throughout the substrate.

Key Technology Characteristics

  • Fast, accurate and repeatable touch response
  • Operation unaffected by surface damage, including Scratches
  • Input flexibility, accepting touch from finger, pencil, credit card, fingernail, or almost any type of stylus
  • Operates with static objects or other touches on the screen
  • Exceptional optical characteristics
  • Scalable for sizes above 32” diameter

Key Features of Dispersive Signal Touch Screen Technology

Advantages:

  • 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"

Disadvantages:

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