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Classification of TP-Liquid Crystal Screen Technology-LCD Display Custom TFT LCD Screen Manufacturer - Topfoison

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Classification of TP

1. Resistive touch screen

These touchscreens are controlled using pressure sensing. Its main part is a resistive film screen, which fits perfectly with the surface of the display. It is based on a layer of glass or hard plastic plate, and the surface is coated with a layer of transparent oxide metal conductive layer (ITO conductive layer), and then covered with a layer of outer surface hardened, smooth, scratch-resistant plastic layer, The inner surface is also coated with a layer of transparent conductive layer, and there is a transparent isolation point support between the two layers of conductive layers. When a finger or a stylus touches the screen, the two conductive layers are in contact at the touch point, the resistance changes, and signals are generated in two XY directions, which are sent to the touch screen control IC. The control IC detects this contact and calculates the position of the XY coordinates, and then operates in the way of simulating a mouse, which is the basic principle of resistive touch screen operation.


2. Capacitive touch screen

Capacitive touchscreens work by utilizing current sensing in the human body. The capacitive touch screen is a four-layer composite glass screen. The inner surface of the glass screen and the interlayer are coated with a layer of ITO conductive film. The outermost layer is a protective layer of silica glass. An intermediate ITO coating is used as the working surface. Four electrodes are drawn from the four corners, and the inner layer of ITO is a shielding layer to ensure a good working environment. When a finger touches the metal layer, due to the electric field of the human body, a coupling capacitance is formed when the user contacts the surface of the touch screen. For high frequency currents, the capacitor is the direct conductor and the finger draws very little current from the point of contact. This current flows out from the electrodes on the four corners of the touch screen respectively, and the current flowing through these four electrodes is proportional to the distance of the finger. The controller IC obtains the position of the touch point by precisely calculating the ratio of the four currents. The light transmittance and clarity of the capacitive touch screen are better than that of the four-wire resistive touch screen, but the reflection is serious, the light transmittance is uneven, and there is a problem of color distortion. If there is water mist on the screen surface, it is easy to touch it by mistake.


3. Infrared touch screen

Infrared touchscreens use a dense infrared matrix in the X and Y directions to detect and locate the user's touch. The infrared touch screen is equipped with a circuit board frame in front of the display screen, and the circuit board is arranged with infrared emitting tubes and infrared receiving tubes on the four sides of the screen, forming a horizontal and vertical infrared matrix corresponding to each other. When the user touches the screen, the finger blocks the horizontal and vertical infrared rays passing through that location, so the location of the touch point on the screen can be determined. Any touch object can change the infrared rays on the touch point to realize touch screen operation. The infrared touch screen is immune to current, voltage and static electricity and is suitable for harsh environmental conditions. Infrared technology is the ultimate development trend in touch screen products.


4. Surface acoustic wave touch screen

Surface acoustic wave is a kind of ultrasonic wave, which is a kind of mechanical energy wave that propagates shallowly on the surface of medium (such as rigid materials such as glass or metal). Through the wedge-shaped triangular base (strictly designed according to the wavelength of the surface wave), directional, small-angle surface acoustic wave energy can be emitted. Surface acoustic waves are stable and easy to analyze, and have very sharp frequency characteristics during shear wave propagation. The touch screen portion of a surface acoustic wave touch screen can be a flat, spherical or cylindrical glass plate mounted in front of a CRT, LED, LCD or plasma display. The upper left corner and the lower right corner of the glass screen are respectively fixed with vertical and horizontal ultrasonic transmitting transducers, and the upper right corner is fixed with two corresponding ultrasonic receiving transducers. The four perimeters of the glass screen are engraved with very precise reflective stripes, 45° from sparse to dense. Surface acoustic wave touch screen features: high definition, good light transmittance. High durability and good scratch resistance (with surface film compared to resistors, capacitors, etc.). Responsive. Not affected by environmental factors such as temperature and humidity, high resolution, long life (50 million times under good maintenance); high light transmittance (92%), can maintain clear and bright image quality; no drift, only need to install once for calibration ; There is also a third axis (ie pressure axis) response, which is currently used more in public places. The surface acoustic wave screen needs frequent maintenance, because the surface of the screen is dusty, oily, or even stained with beverage liquid, which will block the wave guiding groove on the surface of the touch screen, so that the wave cannot be transmitted normally, or the waveform changes, and the controller cannot recognize it normally, affecting the operation. . For the normal use of the touch screen, the user should strictly pay attention to environmental hygiene. The screen surface must be wiped frequently to keep the screen clean, and a thorough and thorough wipe must be performed regularly.

The above is the whole content of Classification of TP, If you want to order LCD liquid crystal display screen , contact us whenever you want, we can customize it for you professionally, Topfoison electronic service Email: info@topfoison.com .

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