Production of a quasi-traveling wave in a silicon rectangular plateusing single phase drive

摘要

A method is proposed in order to produce a quasi-traveling wave onna rectangular plate with a single phase drive. The method is testednusing chemically etched silicon plates. Ultrasonic motors often usentraveling waves. For a traveling wave propagating in an elastic object,nthe particles on the surface move elliptically. Therefore, if a movablenobject is pressed against the surface of an object subject to antraveling wave then the frictional forces between them can induce anmovement. Usually the traveling wave is obtained in a circular plate (ornring) using the combination of two standing waves. These standing wavesncorrespond to a degenerate vibration mode excited by two series ofnpiezoelectric elements. Each series is driven by an electrical powernsource phase shifted to each other. We present a model that shows thenpossibility to obtain a quasi-traveling wave in a rectangular platenusing the superposition of two plate modes (for example modes 2.1 andn1.3). The quasi-traveling wave is obtained along a curve for which thenamplitude of the wave is almost constant and the phase is almostnproportional to the curvilinear coordinate of this curve. If thengeometry is chosen in order to get the same frequency for bothnresonances (f21=f31), the quasi-traveling wave cannbe obtained by the excitation of two phases. If the geometry is suchnthat the frequencies f21and f31 are slightlyndifferent, it is possible to excite both modes with a frequency f,nselected between f21 and f13. In some cases, thenphase shift between the excitation and the mode motion is such that thenquasi-travelling wave is produced. Therefore we obtain a quasi-travelingnwave using a single phase drive. Obviously in this case the amplitude isnreduced by a factor of approximately √2. The experiment isnperformed on a chemically etched rectangular silicon plate. Therefore wenchecked the possibility of producing a linear motion with a statornmanufactured on silicon using microelectronics technology. We concludenthat it is experimentally possible to obtain a quasi-traveling wave on ansilicon plate using only a single phase drive and the experimentalnbehavior is close to that of the model