Capacitive Touch Screen (PCAP)
Projected capacitive touchscreen contains X and Y electrodes with insulation layer between them. The transparent electrodes are normally made into diamond pattern with ITO and with metal bridge.
Human body is conductive because it contains water. Projected capacitive technology makes use of conductivity of human body. When a bare finger touches the sensor with the pattern of X and Y electrodes, a capacitance coupling happens between the human finger and the electrodes which makes change of the electrostatic capacitance between the X and Y electrodes. The touchscreen controller detects the electrostatic field change and the location.
Pros of Capacitive Touchscreen (CTP)
- Looks sharper and brighter
Capacitive Touch Screen uses glass substrate which has high transparency compared with plastic film used by resistive touch panels. Plus, optical bonding and glass surface treatment which make CTP good picture quality and contrast.
- Better Human Machine Experience
Because capacitive touchscreens register touch via the human body’s electrical current, they require less operating pressure than resistive touch panel glass. It supports touch gestures and multi-touch which makes it much better user experience of touch.
- Incredible durability
Because the cover glass is used in front which can be extremely high hardness (>9H), it is extremely durable for touch which can exceed 10 million touches. It also prevents from scratches and easy to clean which makes it prevailing resistive touch panels.
- Size and Appearance
Capacitive touchscreen can be made for very large size (100 inches) and the cover lens can be decorated with different colors, shapes, holes to provide users flexible designs.
Cons of Capacitive Touchscreen (CTP)
Capacitive Touchscreen manufacturing process is relatively more expensive and the cost can be high.
- Immunity to Objects/Contaminants on Screen
Capacitive Touchscreen needs special design and uses special controllers to make it used in special applications, such as using glove to touch, or with water, salt water environment. The cost can be even higher.
The cover lens can crack. In order to prevent glass debris to fly, a film or optical bonding is needed in the manufacturing process to make the price even higher.
Capacitive Touchscreen is easily to be affected by ESD or EMI, special designs have to be considered in the design which can drive the price higher. Special calibration has to be carried out with the help of the controller manufacturer.
- Power and wake up
The power used in capacitive Touchscreen can be higher than resistive touch panel. Sometimes, a hot button has to be designed to wake up the touch function.