Harmonic Drive Systems Inc.

Akira Akahane

Toshiki Maruyama

Nozomu Tanioka

Kunio Miyashita

Yoshinori Ito

Ivan Godler

Hideo Asawa

In a linear actuator (), on the inside of a rectangular tubular movable element (), a linear guide () that supports the movable element () so as to be linearly movable is positioned at a center of the movable element (), and a position detecting mechanism () and load attaching member () that sandwich the linear guide are disposed linearly in a vertical direction. This arrangement enables a center of gravity of the movable element () to be matched with a center of the linear guide (). A magnetic circuit is in a bilaterally symmetrical relationship with regard to the center of the movable element (). Therefore, a center of a thrust force that acts upon the movable element () is matched with the center of the movable element (). The center of the thrust force that acts upon the movable element (), the center of gravity of the movable element (), and the center of the linear guide () are positioned at the center of the movable element (). Resistance to sliding in the movable element () can be reduced without unreasonable stress being placing on the linear guide (). Therefore, a magnetically driven linear actuator that has highly precise positioning and that is durable can be realized.

Linear actuator

In an angle detection device for a rotational body, an external peripheral surface of an arc-shaped fluorescent fiber is scanned by a scanning beam from a scanning mirror fixed to the rotational shaft of a swing motor. Fluorescence is generated at a position in the fluorescent fiber scanned by the scanning beam, the fluorescence is propagated to both ends thereof, and the received luminous energy corresponding to the scanning position is detected by photodiodes. A signal processing circuit compares output signals of the photodiodes to obtain the scanning position of the scanning light, and the corresponding rotation angle of the swing motor is found.

Angle detection device for rotational body

A DC motor of a galvanometer-type scanner has four poles, and compared to a conventional DC motor with a bipolar construction, the armature inductance L can be reduced to half or less for a case where the external diameter of the rotor and the induced voltage constant K are the same. Since K /L, which is the index for the rise of torque of the motor, is increased by a factor of two or more, the responsiveness of the motor can be improved without increasing the exciting current of the winding. Accordingly, it is possible to provide a galvanometer-type scanner that can set minute angles of around one degree within several hundred microseconds.

Galvanometer-type scanner

An optical position sensor comprises a linearity correction circuit 20 having ROM 22 in which a corresponding table between compensation values and respective rotational angular position of a rotational disk 51. The compensation values are obtained such that an actual relationship is measured between the rotational angular positions of the rotational disk 51 and the output B of a semiconductor position sensing device 54, deviation of the output B of the device 54 from a predetermined linearity relationship (A) is calculated, and compensation values are determined for eliminating the deviation of the output B of the device 54 at respective rotational angular positions of the rotational disk 51. The linearity correction circuit 20 retrieves a compensation value E from ROM 22 based on the output B of the device 54, and compensates the output A so as to produce the sensing output E which has a linearity relationship to the rotational angle of the rotational disk 51.

Optical position sensor

Angular acceleration detector

An electromagnetic motor of the finite rotational type has an improved rotor-returning mechanism for exerting a magnetic force to return its rotor to the initial angular position in a non-excited condition. The rotor-returning mechanism is comprised of a permanent magnet fixedly mounted on a stator and a permanent magnet mounted around the rotor. The permanent magnets are arranged such that, a magnetic attractive force generated between the permanent magnets functions to return the rotor to the initial angular position. The rotor-returning mechanism can be constitued by first and second ring-shaped permanent magnets mounted on the rotor. The N and S poles of the first magnet are offset in a the circumferential direction from those of the second magnet so as to generate a magnetic torque for returning the rotor to the initial angular position.

Growing community of inventors

Nagano-ken, Japan

Akira Akahane