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Touch panel introduction and principle

The touch panel is provided with a layer of tin oxide (ATO) and protective film (HardCoatLayer) on the surface of the transparent glass, and an anti-electron signal interference protection (ShieldedLayer) is required between the transparent glass and the LCD Monitor. The touch panel is a direct embodiment of the touch technology and is used to sense contact signals and analyze them.
Touch Panel Technology Introduction The touch panel structure consists of a sensor, a controller, and a software. The sensor, that is, the touch panel part, mainly receives the information inputted through contact; the function of the controller is to analyze and calculate the position of the contact point, and convert the analog signal into a digital signal so that the information device can receive the input signal; the software part The communication protocol between the information processing device and the controller is connected so that the information processing device can receive and recognize the signal input by the controller for subsequent processing actions.
The touch panel can be divided into four types: resistive, capacitive, optical, and sonic, depending on the sensing technology. The following describes the principles and characteristics of various technologies.
Resistive touch panel
The resistive touch panel mainly comprises two upper and lower ITO conductive layers, spacers and electrodes. The ITO glass is mainly used as a substrate, an ITOFilm layer is laminated on the ITO glass, and Spacer is supported in the middle so that the upper and lower plates will not conduct due to close proximity. The silver electrode is then printed on the edges to provide voltage. During use, the upper and lower electrodes are turned on with pressure, and the contact point position is calculated by the controller to detect the panel voltage change and input. The advantages are waterproof, good antifouling property, and good price, but the disadvantages are poor scratch resistance and fire resistance.
Capacitive touch panel
A capacitive touch panel utilizes the change in capacitance generated by electrostatic bonding between a transparent electrode and a human body, and detects its coordinates from induced electrical induction. The sensing principle uses voltage to act on the four corners of the screen's sensing area and forms a fixed electric field. When the finger touches the screen, it can cause the electric field to induce current, which can be determined by the controller according to the ratio of the current angle to the four corners. Calculate the contact position. However, the capacitive touch panel must overcome the noise effects caused by electrostatic charges on the fingers or other touch media, so it is difficult to design the current and the structure. When subjected to pressure, the current ratio can be used to calculate the position.
The component of the capacitive touch panel consists of plating a conductive layer on the glass substrate, fabricating an electrode layer, and finally covering the surface with a protective film, ie, completing the capacitive touch panel, since it is only on a single glass. For the electrode, conduction. The resistive touch panel needs to superimpose the ITO conductive layers on the upper and lower plates, which affects the light transmittance of the entire touch panel. Therefore, the capacitive light transmittance is higher than that of the resistive type and can reach more than 90%. Fire resistance, anti-fouling and scratch resistance of the product are better, and the dust prevention and reaction speed are faster.
Optical touch panel
The principle of the optical touch panel is to use the light source to receive the interrupting principle. The light source and the receiver are arranged within the panel and arranged in a matrix. When the light is interrupted, the position of the signal receiver can be known, and the accuracy thereof can be determined. position. Components of the optical touch panel include a glass substrate, an infrared emitting source, and an infrared receiver. The structure mainly includes the infrared emitting device disposed on the left and the lower side of the glass panel, and the infrared receiver is disposed on the right side and the upper side. When the finger or the contact object intercepts the infrared, the contact can be detected through the information received by the receiver. The position of the point where the matrix is located. The advantage is that the pure glass surface does not affect the light transmittance, the product has high reliability, scratch resistance, and good fire resistance, but the disadvantages are poor waterproof and antifouling properties.
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