The main three types of touch screens are: resistive touch screens, surface acoustic wave touch screens, and capacitive touch screens. Each type of touch screen has its own advantages and disadvantages. To understand which type of touch screen is suitable for that type of application, the key is to understand the working principle and characteristics of each type of touch screen technology.
First, resistance technology touch screen
The main part of the resistive touch screen is a resistive film screen that is very compatible with the display surface. This is a multi-layer composite film with a layer of glass or a hard plastic plate as the base layer and a transparent oxide metal on the surface (ITO indium oxide). , Transparent Conductive Resistor) The conductive layer is covered with a layer of outer surface hardened, smooth rub-resistant plastic layer, and its inner surface is also coated with a layer of ITO coating, between which there are many small (less than 1 / A 1000-inch transparent separation separates the two conductive layers.
When the finger touches the screen, the two conductive layers come into contact with each other at the touch point. The controller detects the touch and calculates the position of (X, Y) and then operates according to the simulated mouse mode. This is the most basic principle of resistive touchscreens.
Since the resistance screen entered the market, it has occupied a large market with stable quality, reliable quality and a high degree of adaptability to the environment. Especially in the field of industrial control, due to the high demands on its environment and conditions, it also shows the uniqueness of resistive screens, making its products account for 90% of the market in similar touch products and has become the mainstream product on the market. Its greatest feature is not afraid of oil, dust, water. G-Touch's latest fourth-generation resistive touch screen differs from other resistive touch screens in that it uses glass as the base plate, which allows higher light transmittance and more reflective refractive index for users.
Second, surface acoustic wave technology touch screen
Surface acoustic wave technology uses sound waves to transmit on the surface of an object. When an object touches the surface, it blocks the transmission of sound waves. The transducer detects this change and reflects it to the computer, which in turn simulates the mouse.
Surface acoustic wave screen features:
High definition, good light transmittance.
High durability and good scratch resistance.
One correction does not drift.
It is suitable for offices, institutions, and places where the environment is relatively clean.
The surface acoustic wave screen needs frequent maintenance because dust, oil, and even liquids of the beverage contaminate the surface of the screen and block the wave guiding groove on the surface of the touch screen, so that the wave cannot be emitted normally, or the waveform can be changed and the controller cannot recognize normally, thereby affecting For normal use of the touch screen, the user must pay strict attention to environmental hygiene. The surface of the screen must be frequently wiped to keep the screen clean and thoroughly erased regularly.
Third, capacitance technology touch screen
Use the body's current sensing to work. When the user touches the screen, due to the human body electric field, a coupling capacitance is formed between the user and the touch screen surface. For the high-frequency current, the capacitance is a direct conductor, so the finger sucks a small current from the contact point. 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. The controller calculates the position of the touch point by accurately calculating these four current ratios. .
Capacitive touch screen features:
It is resistant to most environmental pollutants.
As the human body becomes part of the circuit, the drift phenomenon is serious.
With gloves does not work.
Need to be calibrated frequently.
Does not apply to metal cabinets.
When the outside world has inductance and magnetic induction, it will cause the touch screen to malfunction.
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