Abstract: A teeth cleaning apparatus has a brush pivotally mounted in a brush holder. The brush has a teeth cleaning member such as bristles formed thereon. A vibrator exerts a vibratory force on the brush so that the teeth cleaning member moves back and forth in substantially its axial direction. The vibrator is driven by an electrical signal which preferably is of a frequency between 1,000 and 17,000 Hz and includes an audio frequency component of mixed frequency and amplitude representing music or other pleasant sounds which is transmitted to the auditory system of a person while brushing.

Abstract: The status corresponding to the presence or absence of articles at their reserved locations is detected by means of an optical switch comprising an emitter which sends infra-red rays toward a receiver. The article obstructs these rays and hence its presence is detected. The information obtained from the optical switches is processed and used for servicing or billing.

Abstract: Mobile refractive optical members are placed in a device between the film and stereoscopic direct viewing windows. A drive is provided for driving the film strip bearing stereoscopic images and the mobile refractive optical members at a uniformly constant speed and in synchronism across the fields of view of the viewing windows to provide a fixed image in each window despite the motion of the film; the film strip has a sound track which may be reproduced by conventional reproduction equipment since the film strip is driven at a constant speed.