Projected Capacitive
A capacitive touch screen panel consists of an insulator such as glass, coated with a transparent conductor. As the human body is also a conductor, touching the surface of the screen results in a distortion of the local electrostatic field, measurable as a change in capacitance.
Limitations and considerations
- Because the glass and bezel that mounts it to the monitor can be sealed, the touch screen is both durable and resistant to water, dirt and dust. This makes it practical in harsher environments like gaming, vending retail displays, public kiosks and industrial applications.
- The capacitive touch screen is only activated by the touch of a human finger. Scratches in the coatings can cause dead spots on the screens, so a gloved finger, pen, stylus, or hard object will not work. As a result, it is inappropriate for use in many applications, including medical and food preparation.
- Because the technology was originally created for small screens, it will not scale to larger screens easily and can require periodic recalibration.
Projected capacitive touch detection
Projected Capacitive Touch (PCT) technology is a capacitive technology which permits more accurate and flexible operation, by etching the conductive layer. An XY array is formed either by etching a single layer to form a grid pattern of electrodes, or by etching two separate, perpendicular layers of conductive material with parallel lines or tracks to form the grid (comparable to the pixel grid found in many LCD displays).
Applying voltage to the array creates a grid of capacitors. Bringing a finger or conductive stylus close to the surface of the sensor changes the local electrostatic field. The capacitance change at every individual point on the grid can be measured to accurately determine the touch location.[5] The use of a grid permits a higher resolution than resistive technology and also allows multi-touch operation. The greater resolution of PCT allows operation without direct contact, such that the conducting layers can be coated with further protective insulating layers, and operate even under screen protectors, or behind weather and vandal-proof glass.
Advantages
- Touch function operates through customer-installed materials, including vandal-resistant glass up to 18 mm thick.
- Works outdoors-in rain, snow, ice, and dust.
- True flat front surface possible with no bezel.
- Works with fingers, gloved hands or conductive stylus.
- Works even if glass is scratched or broken.
Disadvantages
- More complex electronics and sensor construction when compared to other technologies
- Does not have full stylus independence support
Touch functionality
- Single touch
Product types
- Glass window (integrated in glass sheet)
- Display solution
- Overlay frame
- Foil
Applied in:
Visual Planet (VTF-32) Projected Capacitive touch foil
Custom setup with VIP foil
Partners
