Hybrid focus using 70 and 40 kHZ ultrasound in mid-air tactile display

Abstract

We examine haptic sensation by a hybrid focus using 70 and 40 kHz ultrasound. The hybrid focus was generated by 70 and 40 kHz phased array. The spatial resolution of 70 kHz phased array is higher than that of 40 kHz case, instead, the attenuation in the air is large in the 70 kHz case. Therefore, a hybrid system is energy-efficient in which a lower spatial frequency component of force pattern is produced by 40 kHz ultrasound and a higher one is created by 70 kHz. In the preliminary experiment, the subjects touched the hybrid focus and reported the similarity of the sensation to the 70 kHz focus.