Seiko Instruments Inc

Koji Nitadori

Tadao Iwaki

Naoki Kawawada

Isamu Takehara

Hiromitsu Goto

Takafumi Suzuki

Yukihiro Nakayama

Atsushi Ohta

Toshiharu Kogure

Atsushi Ota

Ryouji Yoneyama

Shigeru Ohki

Akihiro Iino

Masao Kasuga

Ryoji Yoneyama

Takahumi Suzuki

To provide a control system provided with a positioning mechanism including plural ultrasonic motors in the device, which can keep good operational stability as compared with a conventional system with a servo mechanism, is of an energy saving type suppressing power consumption and is compact in structure including the motor and a control circuit therefor. A control circuit in a control system of the present invention uses a common drive control circuit for a plurality of ultrasonic motors among the positioning mechanisms in which when the drive control circuit inputs a signal that specifies any ultrasonic motor and a desired-position designation signal, the drive control circuit conducts control operation that transmits an on signal to a driver of the subject motor to start the driving, and stops the driving when the motor reaches a desired position while receiving a position detection signal. Thus, the control system has a function of transmitting a signal indicating that the positioning operation is being conducted from a time point when commands are received to a time point when the positioning operation is completed. Then, an error signal is outputted when the motor is out of the desired position.

Control system for ultrasonic motor

A motor has an armature disposed on one of a rotor and a stator and a permanent magnet disposed on the other of the rotor and the stator. The permanent magnet has skewed magnetic poles being magnetized so that a boundary between each pair of skewed magnetic poles is generally S-shaped and opposed areas of pole surfaces of the permanent magnet and the armature gradually increase when the pole surface of the permanent magnet enters a magnetic field region of the pole surface of the armature or gradually decrease when the pole surface of the permanent magnet leaves a magnetic field region of the pole surface of the armature.

Motor

A double sleeve type dynamic bearing comprises a fixed shaft having at least one end fixedly mountable to an apparatus in which the bearing is utilized, a rotary sleeve arranged coaxially with the fixed shaft so that a first fine gap is formed therebetween, a fixed sleeve arranged coaxially with the rotary sleeve so that a second fine gap is formed therebetween, and a lubrication oil filled in the fine gaps. The first fine gap and the second fine gap each have an open end exposed to air outside the bearing and an opposite end that is not exposed to the air, the opposite ends being in communication with each other. A holding member holds the fixed shaft and the fixed sleeve and is disposed adjacent to a lower end surface of the rotary sleeve to form a third fine gap between the holding member and the lower end surface of the rotary sleeve. The third fine gap is formed with a thrust dynamic pressure producing groove, and opposite ends of the first and second fine gaps meet each other through the third fine gap. A peripheral surface of at least one of the fixed shaft, the rotary sleeve and the fixed sleeve forming at least one of the first and second fine gaps has a dynamic pressure producing groove formed therein.

Hydraulic dynamic bearing and spindle motor and rotary assembly provided

A method for lubricating a part without leaving air bubbles includes the steps of assembling components so that an open end is formed for application of lubricating fluid and a fluid path is provided through which the lubricating fluid is to be circulated, introducing the lubricating fluid into the open end and applying a centrifugal force to the component by moving the component about a circular path so that the centrifugal force causes the lubricating fluid to be urged throughout the fluid path. The method is used in an embodiment to lubricate a dynamic pressure bearing having a gap between relatively moving parts. The gap has an open end into which the lubrication fluid is dripped and a closed end. During movement of the bearing about a circular path, the fluid is urged from the open end to the closed end.

Method for lubricating a fluid dynamic pressure bearing

In order to alleviate mutual interference between axial dynamic pressure portions and a radial dynamic pressure portion in a ring-like hydraulic dynamic pressure bearing, in the case of a ring-like hydraulic dynamic pressure bearing constituted by supporting a shaft portion constituted by fixing a ring to an end portion A of a shaft main body by a bearing portion , ring-like spaces and for storing lubricant for generating dynamic pressure are provided along contiguous portions of the radial dynamic pressure bearing portion and the axial dynamic pressure bearing portions formed between the ring and the bearing portion , and the ring-like spaces and are maintained at atmospheric pressure via paths formed at the bearing portion to thereby prevent negative pressure from generating at boundary regions of the two dynamic pressure bearing portions.

Hydraulic dynamic bearing and spindle motor

The present invention is a double sleeve type fluid dynamic pressure bearing, comprising a fixed shaft having respective ends to be fixed to a utilized apparatus; a rotary sleeve arranged to provide a first fine gap between an inner peripheral surface thereof and an outer peripheral surface of the fixed shaft, a fixed sleeve arranged to provide a second fine gap between an inner peripheral surface thereof and an outer peripheral surface of the rotary sleeve, a holder member arranged to cooperate with a lower end surface of the rotary sleeve to provide a third gap, and wherein the first fine gap and the second fine gap are formed with radial dynamic pressure producing grooves while the third fine gap is formed with a thrust dynamic pressure producing groove, the first, second and third fine gaps being filled with lubrication oil, the first fine gap and the second fine gap having one ends made as opening ends contacting with the air and the other ends made as closed ends communicated with each other through the third fine gap.

A hydraulic dynamic bearing has a rotational assembly and a bearing member for rotationally supporting the rotational assembly. The bearing member has a main body having a recess portion and a cover for covering an open end of the recess portion. The rotational assembly has a shaft main body having an end portion extending into the recess of the bearing main body for undergoing rotation relative thereto and a ring member disposed in the recess of the bearing main body. The ring member is connected to the end portion of the shaft main body for rotation therewith. Axial dynamic pressure generating grooves are formed in upper and lower surface portions of the ring member for generating axial dynamic pressure during rotation of the rotational assembly. Radial dynamic pressure generating grooves are formed in an outer peripheral surface portion of the ring member for generating radial dynamic pressure during rotation of the rotational assembly. Spaces are formed between the bearing member and the rotational assembly for storing a lubricant.

Growing community of inventors

Chiba, Japan

Koji Nitadori