Simply put, the surface capacitive touch screen can only be touched directly with a finger, and the projected capacitive touch screen produced by Tonghao touch screen manufacturers can penetrate the tempered glass touch!
Principle of surface capacitive touch screen
The surface, that is, because the sensor is in contact with the person to produce a capacitance value, it does not have a capacitance value itself, so the Z-axis information cannot be judged, and the finger must be touched to determine the coordinate.
The surface of the capacitor screen is plated with a transparent conductive layer ITO, the voltage is connected to the four corners, and the electric charge is distributed on the surface of the screen to form a uniform electric field. When the screen is touched by the hand, the human body acts as a pole of the coupling capacitor.
The current is collected from the four corners of the screen to form the other pole of the coupled capacitor. The controller calculates the relative distance of the current to the touched position to obtain the coordinate value at the touch.
The surface capacitive touch screen can only be touched directly with a finger, while the projected capacitive touch screen can penetrate the tempered glass touch. Generally, the touch screen manufacturers are all making a projected touch screen.
The principle of projected capacitor
The capacitive touch screen produced by the touch screen manufacturer uses the current sensing of the human body to work. 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 outer layer is a thin layer of bauxite glass protective layer, and the ITO coating is used as a working surface.
Four electrodes are led out at the four corners, and the inner layer of ITO is a shield to ensure a good working environment. When the finger touches the metal layer, due to the human body electric field,
The user and the touch screen surface form a coupling capacitor. For high-frequency current, the capacitor is a direct conductor, so the finger draws a small current from the contact point.
This current flows out from the electrodes on the four corners of the touch screen, and the current flowing through the four electrodes is proportional to the distance from the finger to the four corners.
The controller obtains the position information of the touched point by accurately calculating the ratio of the four currents.
Xinhechang touch screen manufacturer reminds you that the capacitive touch screen can be recognized by the system with a touch of touch, and our common resistive touch screen needs to be “pressed” to be perceived by the system.
The advantage of a projected capacitive touch screen is that it is more sensitive, which is the key to the success of the iPhone with a virtual on-screen keyboard.
Therefore, many touch screen manufacturers generally recommend customers to make projected capacitive touch screens. In the past, on the Pocket PC platform, some people have developed a text input system that uses a finger to directly click on the screen.
However, due to the low sensitivity of the resistive touch screen, the phenomenon of "dropping" will inevitably occur when the virtual keyboard input is performed.
It is even more impossible to achieve high speed input. I also suspected the practicality of the iPhone virtual keyboard before I came into contact with the iPhone.
When the actual trial is over, it is found that the virtual keyboard on the projected capacitive technology touch screen can achieve the same input speed as the physical keyboard.
Advantages of touch screen manufacturers' projected capacitive touch screens
• The advantages of projected capacitive touch screens over other touch screen technologies are:
• Excellent signal to noise ratio;
• The entire touch screen surface has high precision;
• Ability to support multiple touches;
• Induction through "thick" dielectric materials;
• No user calibration required.
Market Analysis of Projected Capacitive Touch Screen
• At present, projected capacitive touch screen products have gradually become mainstream in the European and American markets, and shipments continue to rise.
This also greatly promotes the improvement and upgrading of the industrial chain of capacitive touch screen manufacturers. With the gradual improvement of the industrial chain,
The addition of many touch screen manufacturers, the application of new materials, new technologies and new processes will also bring about a decline in various costs.
Thereby reducing the price of the overall module and increasing the competitiveness of the product. ITO Sensor glass occupies more than half of the cost structure of the entire capacitive touch screen.
Therefore, the price trend of ITO Sensor glass will influence the price trend of capacitive touch screen, which directly determines the competitiveness of projected capacitive touch screen in the touch industry.