Surface Acoustic Wave

The touch screen portion of the surface acoustic touch screen can be a flat, spherical, or cylindrical glass panel mounted in front of a CRT, LED, LCD, or plasma display screen. The glass plate is pure reinforced glass and, unlike other touchscreen technologies, has no film or cladding. The upper left corner and lower right corner of the glass screen are fixed with vertical and horizontal ultrasonic transmitting transducers, while the upper right corner is fixed with two corresponding ultrasonic receiving transducers. The four edges of the glass screen are engraved with very precise reflective stripes at an Angle of 45° from sparse to densely spaced.

Transmitting transducer sent controller through the touch screen cable electrical signals into acoustic energy surface to pass to the left, and then by a set of precise reflection stripe at the bottom of the glass plate acoustic energy is reflected into the uniform surface upward transmission, acoustic energy through the screen surface, again by the reflective stripes above to spread to the right line to X axis receiving transducer, receiving transducer will return to the surface of the acoustic energy into electrical signals. In the absence of touch, the waveform of the received signal is exactly the same as the reference waveform. When a finger or other object that can absorb or block the energy of sound waves touches the screen, the energy of sound waves moving up the X-axis through the finger is partially absorbed, reflecting on the received waveform that has a attenuation gap in the waveform at a certain point in time. The received waveform corresponds to the signal attenuation of the finger blocking part. The touch coordinates are obtained by calculating the position of the notch. The controller analyzes the attenuation of the received signal and determines the X-coordinate based on the position of the notch. And then the Y-axis does the same thing to determine the y-coordinate of the touch point. In addition to X and Y coordinates, which can be responded to by the general touch screen, the surface acoustic wave touch screen also responds to the third axis Z-axis coordinates, that is, it can perceive the user's touch pressure value. Once the three axes are identified, the controller passes them to the host machine.

The surface acoustic touch screen is not affected by temperature, humidity and other environmental factors. It has high resolution, excellent scratch resistance and long life (50 million times without fault). High light transmittance (92%), can maintain clear and bright image quality; No drift, best for public use. However, the transducer of the surface induction system will be damaged by the pressure generated by sound energy in long time operation. Wool or leather gloves generally receive part of the sound waves, and the accuracy of the induction is also affected. Water, oil, dirt or dust on the surface of the screen or on the fingers touching the screen can also affect its performance or even cause the system to stop working.