The capacitive touch screen is a layer of transparent special metal conductive material on the surface of the glass. When the finger touches the metal layer, the capacitance of the contact changes, so that the frequency of the oscillator connected to it changes, and the touch position can be determined by measuring the frequency change.
In principle, the capacitive screen uses the human body as an electrode of a capacitor element. When a conductor is coupled to a capacitor with a sufficient capacitance between the working surface of the ITO and the interlayer, the current flowing away is enough to cause the power screen to malfunction. .
The capacitive touch screen is constructed by plating a transparent film layer on the resistive screen and then adding a protective glass to the conductor layer. The double glass design completely protects the conductor layer and the inductor.
The capacitive touch screen is plated with narrow electrodes on all four sides of the touch screen to form a low voltage alternating electric field in the conductive body. When the screen is touched, due to the electric field of the human body, a coupling capacitor is formed between the finger and the conductor layer, and the current from the four electrodes flows to the contact, and the current intensity is proportional to the distance from the finger to the electrode, and the controller located behind the touch screen is The ratio and strength of the current are calculated to accurately calculate the position of the touch point. The dual glass of the capacitive touch screen not only protects the conductors and sensors, but also effectively 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 accurately calculate the touch position.
The capacitive touch screen is a layer of transparent special metal conductive material on the surface of the glass. When the finger touches the metal layer, the capacitance of the contact changes, so that the frequency of the oscillator connected to it changes, and the touch position can be determined by measuring the frequency change. Since the capacitance varies with temperature, humidity, or grounding conditions, its stability is poor, and drift often occurs. This kind of touch screen is suitable for the debugging phase of system development.
Capacitive touch screen defect
The transmittance and clarity of the capacitive touch screen is superior to that of the four-wire resistive screen, and certainly cannot be compared with the surface acoustic wave screen and the five-wire resistive screen. The capacitive screen is seriously reflective. Moreover, the four-layer composite touch screen of the capacitor technology has uneven transmittance for light of various wavelengths, and there is a problem of color distortion. Due to the reflection of light between layers, image characters are also blurred.
In principle, the capacitive screen uses the human body as an electrode of a capacitor element. When a conductor is close to a capacitor with a sufficient capacitance between the working surface of the ITO and the ITO working surface, the current flowing away is enough to cause the capacitive screen to malfunction. .
We know that although the capacitance value is inversely proportional to the distance between the poles, it is proportional to the relative area and also to the insulation coefficient of the medium. Therefore, when a large area of ​​the palm power ic or a hand-held conductor is close to the capacitive screen instead of touching, the capacitive screen may be malfunctioned. In humid weather, this situation is particularly serious, and the hand is held by the display and the palm is close to the display. Within 7 cm of the 7 cm rectifier transformer or within 15 cm of the body, the capacitive screen may malfunction. Another disadvantage of capacitive screens is that they do not respond when touched with a gloved hand or a non-conductive object, because of the addition of a more insulating medium.
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