Ultrasonic fingerprint identification module and electronic equipment

Abstract

The present invention provides a method for calibrating acoustic impedance based on ultrasonic waves, comprising step S1: the ultrasonic sensor sends out ultrasonic transmission signals; step S2: the ultrasonic sensor receives ultrasonic feedback signals; and step S3: obtains ultrasonic transmission characteristics according to the analysis of the ultrasonic transmission signals and the ultrasonic feedback signals parameter; step S4: obtain the prestored ultrasonic transmission characteristic parameters, which are updated in real time to match the change of the ultrasonic transmission path; and step S5: compare the ultrasonic transmission characteristic parameters obtained in steps S3 and S4 to Determine if the acoustic impedance of the ultrasound transmission path has changed. This method at least effectively confirms whether the acoustic impedance of the ultrasonic transmission path has changed, so as to facilitate timely calibration and ensure the sensing accuracy of the ultrasonic sensor. The ultrasonic sensor, ultrasonic fingerprint identification module and electronic equipment provided by the present invention also have the above advantages.

Description

【Technical field】 [0001] The invention relates to the field of ultrasonic waves, in particular to an ultrasonic-based acoustic impedance calibration method, an ultrasonic sensor, an ultrasonic fingerprint identification module and an electronic device. 【Background technique】 [0002] Ultrasonic sensors are sensors that convert ultrasonic signals into other energy signals (usually electrical signals). Ultrasound has the advantages of high frequency, short wavelength, small diffraction phenomenon and strong penetrating power, so it is widely used in industry, national defense, biomedicine and so on. [0003] In recent years, ultrasonic sensors have been applied to consumer electronic products, such as fingerprint recognition of mobile phones. As a fingerprint recognition module, ultrasonic sensors are mounted on mobile phones to detect users' fingerprint information. like figure 1 As shown, it is a schematic structural diagram of the ultrasonic sensor applied to an electron...

AI Technical Summary

Problems solved by technology

When the user is operating, the ultrasonic waves emitted by the ultrasonic sensor 1 need to pass through the adhesive layer 8 and the protective film 6 to reach the user's fingers. Due to the introduction of two different media, it will change the acoustic impedance of the ultrasonic transmission path. Ultrasonic waves produce signal attenuation, and the materials of the protective film 6 and the adhesive layer 8 are different, and the acoustic impedance of the ultrasonic transmission path is also inconsistent. It is difficult for the ultrasonic sensor to match a large number of mobile phones and protective films. Sensitivity drops

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