touchscreenmagazine.nl alles wat u wilt weten over touchscreens

Surface 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.

Surface capacitive touch detection

In this basic technology, only one side of the insulator is coated with a conductive layer. A small voltage is applied to the layer, resulting in a uniform electrostatic field. When a conductor, such as a human finger, touches the uncoated surface, a capacitor is dynamically formed. The sensor's controller can determine the location of the touch indirectly from the change in the capacitance as measured from the four corners of the panel.

Advantages

• Can be used to register touch on a sensor surface through a glass window.
• Capacitive touch screen withstand contaminants such as grease, dirt, water, running liquid, harsh chemicals and can be NEMA-sealed.
• The life expectancy is over 225 million mechanical touches.
• Capacitive technology transmits around 90% percent of the light from the screen.
• Life span of more than more than 50 million touches in one location.
• Technology with fastest touch response time

Disadvantages

• Limited to 1 resolvable touch point
• Can only register the touch of ungloved fingers or tethered stylus on a sensors surface.
• Sensitive for electromagnetic interference.
• Severe scratch can affect operation within the damaged area

Touch functionality

• Single touch

Product types

• Glass window (integrated in glass sheet)
• Overlay frame
• Foil