The touch display is the primary interface for self-service kiosks. At one time it was considered fully optional, now it is pretty much a given (though some keyboard apps still exist).
There are many touch technologies in the market. However many have proven to be niche products, too expensive, not reliable, or difficult to produce. The top touch technologies are projected capacitance, analog resistive, surface capacitive, infrared (IR), and surface acoustic wave (SAW). However, projected capacitive and analog resistive make up 90% of the total market. Other touch technologies include optical touch, multi-touch analog resistive (AMR or MARS), dispersive signal (DST or bending wave), in-cell/on-cell, and acoustic pulse recognition (APR). By analyzing the pros and cons of each, which we do here, you’ll be able to narrow your options by matching up your requirements with the technologies’ capabilities and limitations.
Kiosk Industry Members with touchscreen focus
- Panel Brite LCDs — all types of high bright + digital signage
- TDS TOUCH – touchscreens of all technologies and design
5-Wire Resistive Touch is the most widely used touch technology today. A resistive touch screen monitor is composed of a glass panel and a film screen, each covered with a thin metallic layer, separated by a narrow gap. When a user touches the screen, the two metallic layers make contact, resulting in electrical flow. The point of contact is detected by this change in voltage.
SAW (Surface Acoustic Wave) touch screen monitors utilize a series of piezoelectric transducers and receivers along the sides of the monitor’s glass plate to create an invisible grid of ultrasonic waves on the surface. When the panel is touched, a portion of the wave is absorbed. This allows the receiving transducer to locate the touch point and send this data to the computer. SAW monitors can be activated by a finger, gloved hand, or soft-tip stylus. SAW monitors offer easy use and high visibility. !
Projected Capacitive is similar to Surface Capacitive, but it offers two primary advantages: in addition to a bare finger, it can also be activated with surgical gloves or thin cotton gloves; and it enables multi-touch activation (simultaneous input from two fingers). A projected capacitive is composed of a sheet of glass with embedded transparent electrode films and an IC chip, which creates a three dimensional electrostatic field. When a finger comes into contact with the screen, the ratios of the electrical currents change and the computer is able to detect the touch points.
Surface capacitive touch technology – Surface capacitive (s-cap or surface cap) is a declining technology and is now mostly used in legacy gaming and amusement machines. One positive aspect of surface capacitive is that its optics are as good as projected capacitive and the sensor dimensions can be larger.
Infrared touch screen monitors do not overlay the display with an additional screen or screen sandwich. Instead, infrared monitors use IR emitters and receivers to create an invisible grid of light beams across the screen. This ensures the best possible image quality. When an object interrupts the invisible infrared light beam, the sensors are able to locate the touch point.
Comparison of Elotouch technologies — comparison2007
More info Touchscreen Displays
- Gary Barnett writeup on touch screens
- Touch Screen Tech Comparison Elo
- Planar comparison
- Planar touch technology PDF – How they work
- Touch Systems comparison – link
- Elo comparison 2007
- TRu comparison of touchscreens
- Handbook of visual display technology Robert Phares [link]
- Bill Buxton principal researcher at Microsoft Multi-touch technology history [link] [PDF Buxton]
- Wikipedia Multitouch [link]