Introduction to the principle of capacitive touch screen TP

Capacitive touch screens are divided into:

Surface Capacitive Touch Screen

Projected Capacitive Touch Screen

1)Surface Capacitive Touch Screen

Working principle:

When the user touches the screen, due to the human body's electric field, a coupling capacitor is formed between the finger and the conductor layer. The current emitted by the four-sided electrodes will flow to the touch point, and the strength of the current is proportional to the distance from the finger to the electrode. The processor behind the touch screen will accurately calculate the location of the touch point based on the proportion and strength of the current.

Features:

1. It can sense with a light touch, which is easy to use, and there is almost no wear and tear between the finger and the touch screen. The performance is stable and the service life is long after mechanical testing.

2. The drift phenomenon is relatively serious; it is not suitable for metal cabinets; when there is inductance and magnetic induction in the outside world, the touch screen may malfunction.

2) Projected capacitive touch screen

Basic principle:

The touch screen uses multiple layers of ITO to form a matrix distribution, with the X-axis and Y-axis cross distribution as the capacitance matrix. When a finger touches the screen, the change in capacitance at the touch position can be detected by scanning the X-axis and Y-axis, and then the location of the finger can be calculated. Based on this architecture, projected capacitance can achieve multi-touch operation.

The difference between surface capacitive screen and projection capacitive screen:

1. Surface capacitive screen: mature technology, can not identify multiple points, high price, has strategic alliance, can make screens of various sizes.

2. Projection capacitive screen: immature technology, can identify multiple points, suitable for small and medium-sized screens.