Surface Capacitive touch screen technology
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The surface capacitive touch screen senses the touch behavior of the screen surface by electric field induction. Its panel is a piece of evenly coated ITO layer, and each of the four corners of the panel is connected with the controller by an outgoing line. During operation, a uniform electric field is generated on the surface of the touch screen. When the grounded object touches the screen surface, the electrode can sense the change of the charge on the screen surface and determine the coordinates of the touch point.
The surface capacitive touch screen has long service life and high transmittance, but it has low resolution and does not support multi-point touch. At present, it is mainly used in large-scale outdoor touch screens, such as public information platform (POI) and public service (Sales) platform (POS) and other products.
Transparent conductive coating is on the base glass sheet, and glass protective coating is placed over it. Electrodes are placed on the four corners.
How does it sense the touched points?
The same phase voltage is imposed to the electrodes on the four corners, then a uniform electric field will be forming over the panel. When a finger touches on the panel, electrical current will flow from the four corners through the finger. Ratio of the electrical current flowing from the four corners will be measured to detect the touched point. The measured current value will be inversely proportional to the distance between the touched point and the four corners.
Advantages:
• Surface capacitive technology can be used to register touch on a sensor surface through a glass window.
• Surface capacitive touch screen can withstand contaminants such as grease, dirt, water, and harsh chemicals.
• The life expectancy of surface capacitive is over 225 million mechanical touches.
• Surface capacitive technology transmits around 90% percent of the light from the screen.
• Life span greater than 50 million touches in one location.
•Surface capacitive has high resolution and high response speed.
Disadvantages
• Limited to one resolvable touch point.
• Can only register the touch of ungloved fingers or tethered stylus on a sensors surface.
• Sensitive to electromagnetic interference, or false signals emanating from parasitic capacitive displays.
• Severe scratches can impair operations within the damaged area.
Resistive Technology : Analog 4-wire Resistive, Analog 5-Wire Resistive, Analog 7-wire Resistive, Analog 8-wire Resistive, Features of resistive technology
Capacitive Technology: Surface Capacitive touch technology, Projected Capacitive touch technology
