GEOMETRIC STRUCTURES FOR ACOUSTIC IMPEDANCE MATCHING AND IMPROVED TOUCH SENSING AND FINGERPRINT IMAGING

Improving the accuracy of ultrasonic touch sensing and fingerprint imaging using acoustic impedance matching is disclosed. Acoustic impedance mismatches between an ultrasonic transducer array and a sensing plate can be reduced to maximize energy transfer and minimize parasitic reflections. A reducti...

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Bibliographische Detailangaben
Hauptverfasser:	HIEMSTRA, Daniel J, MAK, George Ho Yin, LI, Hoishun, KHAJEH, Ehsan
Format:	Patent
Sprache:	eng
Schlagworte:	ACOUSTICS ACOUSTICS NOT OTHERWISE PROVIDED FOR CALCULATING COMPUTING COUNTING ELECTRIC DIGITAL DATA PROCESSING METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING,NOISE OR OTHER ACOUSTIC WAVES IN GENERAL MUSICAL INSTRUMENTS PHYSICS SOUND-PRODUCING DEVICES
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Beschreibung
Zusammenfassung:	Improving the accuracy of ultrasonic touch sensing and fingerprint imaging using acoustic impedance matching is disclosed. Acoustic impedance mismatches between an ultrasonic transducer array and a sensing plate can be reduced to maximize energy transfer and minimize parasitic reflections. A reduction in acoustic impedance mismatches can be accomplished using (i) a composite epoxy having a higher acoustic impedance than epoxy alone, (ii) one or more matching layers having an acoustic impedance that is approximately the geometric mean of the acoustic impedance of the sensing plate and the acoustic impedance of the transducer array, (iii) pores or perforations in the sensing plate, or (iv) geometric structures formed in the sensing plate. In addition, parasitic reflections can be suppressed using an absorbent layer.