Noncontact transfer devices are demanded when silicon wafers or glass plates are carried in clean environment. Because contact of such products with a conveyer belt damages and contaminates their surface, non-contact transfer devices are preferable. Many transfer devices using ultrasonic, electromagnetic or electrostatic levitation have been proposed. The ultrasonic levitation using the squeeze effect can be applied to thin plates [1]. A travelling wave was added to the levitation to transfer the plates [2][3]. A device combining two sets of a 1-directional device carries a plate in two directions [4]. The authors also have proposed a two-dimensional transfer method using ultrasonic levitation [5]. Because it utilizes repulsive force, gap sensors to measure the levitation distance are not needed. Electromagnetic properties do not affect the levitation and transfer performance. In this paper, a driving force in a transfer device with two degrees of freedom using ultrasonic levitation is analyzed by measuring the vibration and pressure.
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