Harmonic Drive Systems Inc.

Other

Yoshinori Ito

Kazuhiro Hane

Muneo Mitamura

Toshiki Maruyama

Akira Akahane

Hiroshi Kameda

Toshiyuki Abe

Toshiaki Kamata

Sadaharu Kanamori

A projection linear encoder has an SOQ substrate formed with transmission gratings and grid-like photodiode groups, and a reflecting grating plate with reflecting gratings that are formed facing thereto. A light-blocking film composed of a metal thin film or the like is formed on a surface of a glass substrate of the SOQ substrate, and the transmission gratings are formed by patterning the light-blocking film. The photodiodes are integrally formed by epitaxial growth on the silicon layer of the SOQ substrate. Transmission gratings with high mechanical strength can be formed inexpensively in comparison with cases in which through holes are formed by etching a silicon substrate to manufacture transmission gratings.

Projection encoder with moving side gratings and fixed side gratings

In an encoder signal interpolation divider () that automatically corrects errors in the offset and gain of an input signal at a high speed with a low cost circuit configuration, and can accurately generate an encoder signal having a predetermined resolution by interpolation division, analog input signals (A, B) are subjected to offset correction by a 0-point correction circuit () in adders () prior to being digitally converted by A/D converters (), and are subjected to gain correction by an amplitude correction circuit () in amplifiers (). The corrected analog signals are converted to digital values, angle data is calculated in an angle data lookup table (), and, based on these results, an encoder pulse signal having a predetermined resolution is generated and output from an encoder pulse signal generating circuit ().

Encoder signal interpolation divider

In a projection encoder based on a triple-grating concept, a light-transmitting grating group for detecting A- and B-phase signals, a photodiode group for detecting A- and B-phase signals, and a photodiode group for detecting a home position are formed on a movable grating plate of a projection linear encoder ; and a reflecting grating group for detecting A- and B-phase signals, and a reflecting grating group for detecting the home position are formed on a reflecting grating plate

Projection encoder

In an optical linear encoder, light from an LED passes through a moving grating formed in a semiconductor moving plate and is reflected by a reflective grating of a reflective grating plate An image of the reflective grating is detected by photodiodes that are formed in the shape of a grid on the semiconductor moving plate The moving grating and the photodiodes are formed on the same semiconductor substrate with the photodiodes in the form of a grid having a lens effect. Consequently, a lens optical system is not required, making it possible to produce a compact, small-scale encoder. A differential signal for an A-phase signal obtained from a group of photodiodes arranged on the semiconductor substrate and an inverse of this signal is produced as the A-phase signal, and a differential signal for a B-phase signal and an inverse of this signal is produced as the B-phase signal, so that an encoder output with little error can be obtained.

Optical encoder

A positioning system in which a absolute sensor detection signals are communicated to a controller, which is a personal computer, via a PC card. The PC card is provided with sensor connection terminals, a converter for converting sensor detection signals to digital position signals, PC connection terminals, a sensor drive circuit, and a switching circuit. The sensor switching circuit switches sensor connection terminals in accordance with commands from the personal computer, whereby one absolute sensor is excited or driven by the drive circuit, and detection signals from that sensor are converted to digital position signals that are fed to the personal computer. Using a PC card thus configured makes it possible to readily configure a positioning system having a plurality of absolute sensors.

Positioning system

An absolute sensor has a high speed side encoder mounted on a high speed rotational shaft , a low speed rotational shaft arranged coaxially with the high speed rotational shaft , a planetary gear mechanism for reducing the speed of rotation of the high speed rotational shaft and delivering the rotation of reduced speed to the low speed rotational shaft . The planetary gear mechanism has a fixed sun internal gear a, a front stage planetary gear b, a rear stage planetary gear c, and an output sun internal gear d connected to the rear stage planetary gear c and low speed rotational shaft , wherein the planetary gears b and c are rotatably supported by an eccentric shaft portion of the shaft . The planetary gear mechanism can be constituted so that the input and output shafts are arranged coaxially, and can be made small with having a large reduction ratio in comparison with the conventional reduction mechanism comprised by spur gears.

Absolute sensor

A multi-function type absolute converter comprises a sensor I/O port having a plurality of sensor connection terminals that can be connected to a plurality of absolute sensors, a conversion circuit for converting absolute sensor detection signals input via the sensor connection terminals to digital position signals, a PLD that can perform prescribed processing on the digital position signals thus generated, a host I/O port having output terminals for outputting the digital position signals and signals generated by the programmable logic device, a switching circuit for switching sensor connection terminals, and a control circuit for controlling each part, the control circuit comprising mainly a CPU, ROM and RAM. The inclusion of a PLD enables the multi-function type absolute converter to be flexibly adapted to user specification.

Multi-function type absolute converter

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.

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Nagano-ken, Japan

Yoshinori Ito