Abstract: A rotation angle detecting device with a pair of variable capacitors which are formed with a rotating object, i.e. a movable electrode, and two stationary electrodes disposed around the rotating object, so that the capacitors operate in a differential mode. Alternatively, the central electrode can be stationary while the two outer electrodes move with the rotating object. The capacitors are combined with oscillators, so that a signal varying with the rotation of the rotating object is provided by obtaining the difference between the output frequencies of the oscillators.

Abstract: A device for measuring the amount of rotation of a rotating object is provided with a sensor unit made up of the rotating object and stationary members arranged to form two pairs of capacitors therebetween. The confronting surfaces of the rotating object and stationary members are graduated with gear-like cuts so that while the capacitances of two of two pairs of capacitors are maximum, the capacitances of the other capacitors are minimum. The device further comprises a pair of oscillators coupled to the two pairs of capacitors, and a mixer connected to the oscillators so that the difference in capacitance between the capacitors is obtained as the difference in frequency, which is processed to provide the amount of movement of the moving object.

Abstract: A device for measuring the amount of movement of a straightly moving object is provided with a sensor unit made up of the straightly moving object and stationary members arranged to form two pairs of capacitors therebetween. The confronting surfaces of the moving object and stationary members are graduated with gear-like cuts so that while the capacitances of two of the capacitors are maximum, the capacitance of the other capacitors are minimum. The device further comprises a pair of oscillators coupled to the two pairs of capacitors, and a mixer connected to the oscillators so that the difference in capacitance between the capacitors is obtained as the difference in frequency, which is processed to provide the amount of movement of the moving object.

Abstract: In a face gear assembly comprising a face gear and a pinion engaged therewith, the crest or top land of each tooth of the face gear is so formed as to touch the root surface or bottom land between two adjoining teeth of the pinion which are in mesh with the tooth, whereby the mutual engaging relationship of the face gear and the pinion can be regularly maintained.

Abstract: A minute change detecting system comprises sensor means which changes its electrical constant according to a physical change of an object under measurement to affect the oscillation frequency of at least one of two high-frequency oscillators, and mixer means for producing a beat frequency signal from the output oscillation frequencies of the two oscillators, thereby to detect the physical change.