Ask about the principle of capacitive stylus, it is too expensive on the market, so you can copy one

It works by using the current induction of the human body.

The capacitive touch screen is a four-layer composite glass screen, the inner surface and the interlayer of the glass screen are each coated with a layer of ITO (coated conductive glass), the outermost layer is a thin layer of silica glass protective layer, ITO coating as the working surface, four electrodes are drawn out at the four corners, and the inner layer of ITO is the shielding layer to ensure a good working environment. When the finger touches the metal layer, the finger draws a small current from the contact point due to the formation of a coupling capacitance between the human electric field, the user and the surface of the touch screen, which is a direct conductor for high-frequency currents. This current flows from the electrodes on the four corners of the touch screen, and the current flowing through these four electrodes is proportional to the distance from the finger to the four corners, and the controller obtains the position information of the touch point through the accurate calculation of the proportion of these four currents.

The structure of the capacitive touch screen is mainly to coat a transparent thin film conductor layer on the glass screen, and then add a protective glass outside the conductor layer, and the double glass design can completely protect the conductor layer and the sensor.

Capacitive touch screens are plated with narrow electrodes on all four sides of the touch screen to form a low-voltage alternating current field in the conductive body. When touching the screen, due to the electric field of the human body, a coupling capacitance will be formed between the finger and the conductor layer, and the current emitted by the four electrodes will flow to the contact, and the current strength is proportional to the distance from the finger to the electrode, and the controller behind the touch screen will calculate the proportion and strength of the current to accurately calculate the position of the touch point. The double glass of the capacitive touch screen not only protects the conductor and sensor, but also prevents external environmental factors from affecting the touch screen, even if the screen is stained with dirt, dust or oil, the capacitive touch screen can still accurately calculate the touch position.

A capacitive touch screen is a layer of transparent special metal conductive substance attached to the surface of glass. When a finger touches a metal layer, the capacitance of the contact changes, causing the frequency of the oscillator connected to it to change to change, and information can be obtained by measuring the frequency change to determine the touch position. Since the capacitance changes with temperature, humidity or grounding, it is not stable and tends to drift.

This touch screen is suitable for the commissioning phase of system development.

Depending on what kind of pen you are asking, it can be divided into capacitive active pen and capacitive passive pen.

Capacitive active pen means that there is a circuit in the pen, and the pen transmits signals to the touch screen matrix to receive to detect the coordinates of the pen.

A capacitive passive pen can treat it as a finger that does not emit signals by itself, but contact with the touch screen can change the capacitance of the touch screen matrix. This kind of pen does not emit signals, so either the pen head is very large (in order to have enough sensitivity, like many iPad pens); Either the phone focuses on this feature, and the touch screen resolution is specially designed for passive pens with a high level.

However, there are many very smart capacitive pens on the market, and IQS not only supports writing small print. In addition to the tilt pressure sensitivity function and the anti-mistouch function, it is also very affordable and convenient.