1:45 PM - 2:00 PM
[5p-C22-3] An acoustic levitation system for planar objects using a bending vibrator and a reflector
Keywords:acoustic levitation, noncontact transportation
This paper investigates acoustic levitation of a planar object using a standing-wave field. Lightweight and thin planar objects, such as paper, can be suspended in an acoustic standing wave in air as with a small particle. The acoustic levitation system was developed; it consists of a 1-mm-thick and 400-mm-long bending vibrating plate and two ultrasonic bolt-clamped Langevin transducers with step horns. A plane reflector was installed parallel to the vibrating plate at a distance of approximately 7 mm to generate an ultrasonic standing wave between them to trap a planar object along the nodal line. The configuration of the vibrating plate and the positions of the two transducers were determined from finite element analysis. The distribution of the vibrational displacement amplitude was measured experimentally using a laser Doppler vibrometer, and an in-phase flexural vibration mode with a wavelength of approximately 20 mm was excited on the vibrating plate at the resonance frequency of 25 kHz. A piece of polystyrene plate (thickness: 1 mm; weight: 1.04 g/cm3) could be levitated along the horizontal nodal line of the standing wave. The levitation position in the vertical direction changed with the vibrational displacement amplitude of the plate; the position was determined by the balance between the weight and the acoustic radiation force for the plate. The sound pressure distribution was measured using a probe microphone to investigate the relationship between the levitation position and the sound pressure distribution. By controlling the driving phase difference between the transducers, the position of the flexural vibration on the vibrating plate can be shifted in the length direction, and the trapped planar object can be moved 10 mm in the same direction when the phase difference was changed from 0 to 360º.