Front Screen Glass Lens For IphoneXSMAX with OCA

                                                                               How Surface Acoustic Wave Touchscreens Work

Take the X-axis transmitting transducer in the lower right corner as an example: the transmitting transducer converts the electrical signal sent by the controller through the touch screen cable into sound wave energy and transmits it to the left surface, and then a set of precise reflection stripes under the glass plate Reflect the sound wave energy into an upward uniform surface, the sound wave energy passes through the surface of the screen, and then gathers the reflection stripes on the upper side into a right line and propagates to the X-axis receiving transducer, and the receiving transducer will return the surface acoustic wave The energy becomes an electrical signal.

     When the transmitting transducer emits a narrow pulse, the sound wave energy reaches the receiving transducer through different paths, the rightmost one arrives the earliest, the leftmost one arrives the latest, and the early and late arrivals are superimposed into one Wider waveform signal, it is not difficult to see that the received signal gathers all the sound wave energy returning through different paths in the X-axis direction, and they travel the same distance on the Y-axis, but on the X-axis, the farthest than The closest one has gone twice as far as the maximum distance on the X axis. Therefore, the time axis of this waveform signal reflects the position of each original waveform before being superimposed, that is, the X-axis coordinate.
     Transmitting signal and receiving signal waveform When there is no touch, the waveform of the receiving signal is exactly the same as the reference waveform. When a finger or other object that can absorb or block sound wave energy touches the screen, the sound wave energy that goes upward on the X-axis through the finger is partially absorbed, reflecting an attenuation gap on the received waveform, that is, at a certain moment in the waveform.
     The received waveform corresponds to a gap in the signal attenuation of the part blocked by the finger, and the position of the gap is calculated to obtain the touch coordinates. The controller analyzes the attenuation of the received signal and determines the X coordinate from the position of the gap. After that, the same process of the Y axis determines the Y coordinate of the touch point. In addition to the X and Y coordinates that general touch screens can respond to, the surface acoustic wave touch screen also responds to the third axis Z-axis coordinates, that is, it can sense the value of the user's touch pressure. The principle is calculated by the attenuation at the attenuation of the received signal. Once the three axes are determined, the controller will pass them to the host.