Producing airborne ultrasonic 3D tactile image by time reversal field rendering

In this paper, we propose a method to render ultrasound pressure distribution in an inhomogeneous field by surrounding phased array especially for the purpose of invoking tactile sensation to human skins. Our previous work showed that ultrasound stationary radiation force can invoke tactile sensation for user´s finger in 3D cavity which is surrounded by ultrasound transducers. However, disturbance of an acoustic wave field by user´s hand is not negligible and therefore the sensed haptic force decreases. In addition, ways to present arbitrary spatial form are also desired. The proposed method renders the pressure field and reconstructs it by finite element method and time reversal method. This method can be applied to inhomogeneous field with the presence of fingers or palms and can create complicated images.