Ntn Corporation

Kazuyuki Aono

Yoshio Fujikawa

Akio Nakajima

Kiyotaka Kusunoki

Ryu Inoue

Even when there is some degree of variation in the characteristics among components constituting a polyphase motor and a driving circuit therefor, current control signals of respective phases being input to the drive circuit have their amplitude finely adjusted by an amplitude control circuit, so that amplitude is uniform among armature currents of respective phases that are ultimately output from the drive circuit. The amplitude adjusting circuit is configured by gain variable amplifiers, for example. Thus, rotation fluctuation and vibration of the polyphase motor can be reduced.

Drive control circuit for polyphase motor capable of reducing variation among armature currents of respective phases, and spindle apparatus using the same

An externally pressurized gas bearing comprising a main shaft, and journal bearing sections having a plurality of axial gas feed rows each having a plurality of circumferentially equispaced gas feed holes, the gas feed holes in the gas feed rows being adapted to spout compressed gas to thereby rotatably radially support the main shaft in a non-contact state, the externally pressurized gas bearing being arranged so that the gas feed holes in the gas feed row are disposed so as to be positioned circumferentially intermediate between gas feed holes in the adjoining gas feed row.

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Iwata, Japan

Kazuyuki Aono