| 摘要 |
<p>6D-5316 In a first embodiment, a control device includes a housing having a serpentinely disposed channel and a cover, secured to the housing, which converts the channel into an ultrasonic waveguide. One end of the waveguide is bounded by a stationary reflector and the other end of the waveguide holds a piezoelectric transducer matched to the waveguide so as to provide therein, when actuated, a propagating transverse wave in the ultrasonic frequency range. The cover includes a plurality of slots communicating with the waveguide, each slot being located at a different position along the propagation path of the waveguide; and a plurality of resiliently mounted reflectors, each reflector being associated with a different one of the slots and being insestable into the waveguide by, for example, fingertip pressure. Actuation of the transducer by an electrical pulse causes an ultrasonic pulse to propagate down the waveguide. The pulse is reflected back to the transducer, by the stationary reflector or an inserted reflector, where a delayed pulse is caused to appear. The delay is related to the position along the propagation path of the inserted reflector or the stationary reflector. In a second and similar embodiment, a piezoelectric transducer is coupled to a resilient elongated waveguide, and selectable means are used to temporarily pinch the waveguide along its length. The means selected determine the delay time of pulses transmitted and reflected back to the transducer.</p> |
