Lamb wave surface acoustic wave touch point positioning method based on piezoelectric array

Abstract

The invention relates to a Lamb wave surface acoustic wave touch point positioning method based on a piezoelectric array, and the method comprises the steps: arranging N piezoelectric sensors on a to-be-detected surface acoustic wave touch screen to construct the piezoelectric array, sequentially selecting one piezoelectric sensor as an exciter, taking the remaining piezoelectric sensors as a receiver, and building a piezoelectric excitation -sensing channel; lamb wave response signals of all the piezoelectric excitation -sensing channels are collected, and an effective signal segment is captured by adopting an effective signal self-extraction algorithm; carrying out one-dimensional discrete wavelet transform on the captured effective signal segment by adopting a one-dimensional discrete stationary wavelet transform (SWT) method, comparing a Lamb wave response signal with an excitation end direct wave amplitude, and calculating an amplitude / energy relative change rate; and setting an amplitude / energy relative change rate threshold, further dividing the original touch area, determining a touch point existing area, and determining the touch point position of the touch point existingarea by utilizing an ellipse positioning algorithm. According to the method, the sensor array arrangement difficulty is simplified, and the touch point positioning precision is high.

Description

Technical field[0001]The invention belongs to the field of touch screens, and in particular relates to a method for locating Lamb wave surface acoustic wave touch points based on a piezoelectric array.Background technique[0002]The working principle of the existing surface acoustic wave touch screen is that vertical and horizontal ultrasonic transmitting transducers are fixed on the upper left corner and the lower right corner of the touch screen, and two corresponding ultrasonic receiving transducers are fixed on the upper right corner. The four peripheries of the glass screen are engraved with very precise reflection stripes with 45° angles ranging from sparse to dense. Taking the X axis as an example, the control circuit generates an electrical signal which is converted into the ultrasonic wave vibrating in the thickness direction by the X axis transmitter on the touch screen. The ultrasonic wave is refracted by the wedge seat under the transducer and propagates along the glass su...

AI Technical Summary

Problems solved by technology

[0003] However, in this surface acoustic wave touch screen touch point positioning method, if dust, oil, etc. are stained on the touch screen surface, the waveguide groove on the touch screen surface will be blocked, so that the wave cannot be launched normally, or the waveform will change and the controller cannot recognize it normally.

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