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Detailed Program
Paper Number : PI-I05
Time Frame : 15:00~15:20
Presentation Date : Thurseday
Session Name : Piezoelectric Materials, Devices & Applocations
Session Chair 1# : In-Tae Seo
Session Chair 2# : Tomoaki Mashimo
Resonant-type Smooth Impact Drive Mechanism (R-SIDM)
Takeshi MORITA
The University of Tokyo
Smooth impact drive mechanism (SIDM) is one of the stick-slip (or slip-slip) linear actuators, which enables high-speed operation with a simple structure. Previous SIDM actuators have been practically applied in camera modules, cell phones, and blue-ray disc devices[1]. The SIDM actuator is composed of a piezoelectric stator and a slider preloaded to the stator. The stator is driven in two stages: a slow forward motion and a rapid backward motion, namely saw-shaped displacement. Conventional SIDMs were driven at off-resonant frequency; therefore, a large input voltage was indispensable, which caused a heat generation.
In this study, we proposed a resonant-type SIDM (R-SIDM) actuator. This principle utilizes a quasi-saw-shaped displacement obtained by combining two resonant vibrational modes as shown in Fig. 1. The resonant effect enables low input voltage operations, which means small the heat generation. In order to combine two longitudinal vibration modes, the frequency ratio must be 1:2. By using the transfer matrix method and the FEM, we found that one solution is inserting a cupper disk between the piezoelectric part and the CFRP rod. In addition, almost constant velocity was obtained at driving area (CFRP rod). With a preload of 270 mN, the no-load speed was 40 mm/s with 1.6 V as shown in Fig. 2. This input voltage was one-sixth that of previous SIDMs for the same performance and the heat generation was suppressed effectively from 130 to 40 degree C.
Using the same principle, other kinds of the R-SIDMs were examined. One example is a miniaturized R-SIDM actuator, whose stator length was 10 mm. A piezoelectric plate was adhered to the step-shaped metal bar. This step design was important for realizing 1:2 resonant frequency ratio. Other example is a wireguide driven R-SIDM. At the tip of a step-shaped Langevin transducer, an aluminum wireguide (diameter 1mm) was attached. The quasi-saw shaped displacement was propagated from Langevin transducer to the tip of this wireguide for the R-SIDM operation. The length of wireguide was 326 mm at most; however, a longer wireguide, more than 1 m, could be possible.
Acknowledgements :