About Projected Capacitive Panel

- Nov 28, 2019-

Touch technology of projected capacitive panel Projected capacitive touch screen is to etch different ITO conductive circuit modules on two layers of ITO conductive glass coating. The etched patterns on the two modules are perpendicular to each other, and they can be regarded as sliders that continuously change in the X and Y directions. Since the X and Y structures are on different surfaces, a capacitor node is formed at the intersections. One slider can be used as a drive line, and the other slider can be used as a detection line. When a current passes through one of the driving wires, if there is a signal of a change in capacitance, it will cause a change in the capacitance node on the other layer of wire. The change in the detection capacitance value can be measured by the electronic circuit connected to it, and then converted to a digital signal by the A / D controller to allow the computer to perform arithmetic processing to obtain the (X, Y) axis position, thereby achieving the positioning purpose.

3M displays 60-point capacitive touch screen

3M displays 60-point capacitive touch screen [4]

During operation, the controller successively supplies current to the driving wires, so that a specific electric field is formed between each node and the wires. Then scan the sensing line column by column to measure the capacitance change between the electrodes to achieve multi-point positioning. When a finger or a touch medium approaches, the controller quickly detects the change in the capacitance between the touch node and the wire, and then confirms the position of the touch. One axis is driven by a set of AC signals, and the response through the touch screen is sensed by electrodes on the other axis. Users call this "cross-through" sensing, which can also be called projection sensing. The sensor is plated with ITO patterns on the X and Y axes. When a finger touches the surface of the touch screen, the capacitance value under the touch point increases according to the distance of the touch point. The continuous scanning on the sensor detects the change in capacitance. The control chip calculates the touch points and returns them to the processor.