Akinori Miyamoto

Backside observation technique for SAW distribution under electrodes

A modified SAW distribution observation technique, which employs the polarization detection method, has been developed. A probe light was projected from the backside of the substrate to detect the SAW under the electrodes. The observed results proved that the origin of the leakage SAW is the penetration from the IDT (inter digital transducer) to the electrodes, and busbars transmit the wave as waveguides.

Novel optical observation technique for shear horizontal wave in SAW resonators on 42/spl deg/YX-cut lithium tantalate

We developed a new optical technique for observing the shear horizontal component of surface acoustic waves. The technique detects the change in polarization of the probe light caused by the photoelastic effect. We measured the distribution in and around a resonator on rotated Y-cut LiTaO/sub 3/, and occurrence and propagation of leakage was observed.

Observation of waves propagating within a substrate

We developed a technique for observing the distribution of acoustic waves based on polarization detection. This technique enabled visualization of wave distributions in an LiTaO/sub 3/ substrate at various depths. Significant differences of the distribution in the substrate were observed at different frequencies. At the resonant frequency, the waves were distributed near the surface of the resonator. In contrast, a non-negligible amount of the acoustic wave was detected in a deeper area (4/spl lambda/) above the anti-resonant frequency. This improved technique enables us to observe the behavior of acoustic waves both on the surface and in the substrate.

Analysis of Ultrasound Radiation and Proposal of Design Criteria in Ultrasonic Haptic Display for Practical Applications

This paper describes a technology to reduce ultrasound radiation which is caused by normal mode vibration of an ultrasonic haptics display. Reduction and analysis of ultrasonic acoustic radiation from the display were implemented for safety use and coexistence with other devices. The focus on solving the problem of ultrasound radiation is based on the investigation of constructive interference conditions of acoustic waves on the top panel. We successfully demonstrated a practical sound pressure level on the prototype. To reduce radiation, it is necessary to reduce the thickness or the lower stiffness-to-density ratio E/ρ. A thickness of 0.3 mm has practical stiffness in the case of glass and the maximum pressure is 110 dB or less at 30 kHz for the usual size of smartphone. This means that raising the “coincident frequency” higher than the driving frequency by reducing the thickness and lowering the E/ρ, causes sound radiation to be sharply reduced.