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Surface Acoustic Wave Touch Screen Works



Surface acoustic wave touch screen works

The touch screen portion of a surface acoustic wave touch screen can be a flat, spherical or cylindrical glass plate mounted on the front of a CRT, LED, LCD, or plasma display screen. This piece of glass plate is just a pure tempered glass, different from other types of touch screen technology is no foil and coating. Upper and lower right corner of the glass screen are fixed vertical and horizontal ultrasonic transducer, the upper right corner is fixed two corresponding ultrasonic receiver transducer. The four sides of the glass screen are engraved with a 45 ° angle from sparse to densely spaced reflective stripes.

How it works Take the X-axis 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 energy to be transmitted to the left surface and then reflects the sound energy wave into an upward uniform surface by a group of fine reflection stripes below the glass plate. The surface of the screen body is then converged to the right line by the reflective stripes on the upper side to the receiving transducer of the X-axis, and the receiving transducer changes the surface acoustic wave energy returned to the electrical signal.

When the transmitting transducer emits a narrow pulse, the acoustic energy reaches the receiving transducer in different ways, and the earliest arrivals to the far right, the leftmost arrivals, the early arrivals and the late arrivals, are superimposed into one It is not difficult to see that the received signal is a collection of all the acoustic energy that has traveled along the length and the short path in the X-axis direction. The distance traveled by the Y-axis is the same. However, in the X-axis, the farthest ratio More recently walk twice the maximum distance of the X axis. Therefore, the time axis of this waveform signal reflects the position of each original waveform before superimposing, that is, the X-axis coordinate.

Transmitting and Receiving Waveforms When there is no touch, the received signal has exactly the same waveform as the reference waveform. When a finger or other object capable of absorbing or blocking sonic energy touches the screen, the sound energy of the X-axis traveling upward through the finger portion is partially absorbed, and the waveform of the waveform has an attenuation notch at the receiving waveform.

Receive waveform corresponding finger blocking part of the signal attenuation of a gap, the calculation of the gap location that touch coordinate controller to analyze the attenuation of the received signal and determine the position of the gap X coordinate. After Y axis the same process determines the Y coordinate of the touch point. In addition to the general touch screen can respond to the X, Y coordinates, the surface acoustic wave touch screen also respond to the third axis Z-axis coordinates, which is able to perceive the value of the user touch the pressure value. The principle is calculated by the amount of attenuation at the receive signal attenuation. Once the three axes have been determined, the controller sends them to the host.


Hangzhou Kaike Electronics Co., Ltd.

Address: No. 2. Dadi Road, Haining Agricultural External Development Zone 314408,

Zhejiang, China

Contact Person: May Wong

Telephone: 86-571-86830690     Fax: 86-571-86687367

Cell Phone: 86-15158112598

Email: May@hzkaike.cn

Website: www.hzkkelec.com          

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