Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Yoichi Ohmura

Toru Oka

Hajime Nakajima

Takashi Okamuro

Hirokazu Sakuma

Masahiko Sakamoto

Takeshi Musha

Toshikazu Kitagaki

Hiroshi Nishizawa

Koichi Sugimoto

Yukio Aoki

Toshiro Nakashima

Toshikazu Satone

The present invention provides a magnetic rotational-angle detector capable of detecting a position and a rotational angle of a rotating member with excellent accuracy. The magnetic rotational-angle detector includes device arrays () constituted by a plurality of magnetic sensor devices which are arranged to cancel the n-th order harmonic components by each other. In the device arrays, the magnetic sensor devices corresponding to each other are arranged such that they are spaced apart with a distance of (2m+1)&#x3bb;, and the arrangement of all the magnetic sensor devices and their orientations with respect to a power-supply terminal and a ground terminal are axisymmetrical about a straight line () passing through a barycenric position () of all the magnetic sensor devices which is positioned on a straight line along a radial direction of a rotating drum ().

Magnetic rotational-angle detector

An optical encoder for measuring a relative movement of a first scale plate and a second scale plate, comprises: a light source; a first scale plate which converts light from the light source into a cyclic light quantity distribution; a second scale plate which cyclically makes spatial modulation on the light beams from the first scale plate; a third scale plate having slits which allow the light beams from the second scale plate to pass therethrough; and a light-receiving element which receives the light beams from the third scale plate; a lens which converts light from the light source into substantially parallel light beams; and an optic array which converges or diffuses light beams in the direction of periodic change and generates a cyclic light quantity distribution on the first scale plate.

Optical encoder applying substantially parallel light beams and three periodic optical elements

In an optical encoder comprising an optical scale in which a light transmission portion and a light non-transparent portion are arranged and an output pattern obtained by emitting an incident light functions as an optical code, a light source portion and a light detecting portion, the light non-transparent portion is constituted of at least one pair of inclined surfaces which are opposed in such a manner as to become farther away from each other towards the side where the incident light enters and set so that an incident angle of the optical axis of the incident light from the light source should not be smaller than a critical angle of incidence, and the light non-transparent portion is constructed so that the incident light which enters one inclined surface should be totally reflected thereon to enter the other inclined surface and then at least part of the incident light should be reflected on the other inclined surface, and a reflected light which is reflected on the other inclined surface should not enter a light emitting portion of the light source and a reflecting portion around the light emitting portion.

Optical encoder having a no track portion of an optical scale being placed at a position symmetrical to a light non-transparent portion within an irradiation region of incident light

An optical encoder includes an incoherent light source; a first grating, which is an amplitude grating having a first grating period, for spatial amplitude modulation of the incoherent light from the light source; a second grating, which is a phase grating having a second grating period, for spatial phase modulation of light from the first grating; a third grating, which is an amplitude grating having a third grating period, for spatial amplitude modulation of light from the second grating; and a light detecting element for detecting light from the third grating. The encoder detects relative displacement between the respective gratings. The optical transfer function from the light source to the light detecting element is enhanced, and the efficiency in utilizing light is improved.

Optical encoder

An optical encoder includes: a rotary slit plate having a rotation angle detection track including an optical slit; a light source for applying light to the optical slit; light detecting elements for rotation angle detection and arranged at positions to which light emitted from the light source is applied to the optical slit, to detect the light emitted from the light source and passing through the optical slit; and light detecting elements for light amount monitoring arranged at locations on a circumference in corresponding relationship with positions to which light emitted from the light source is applied to the optical slit, to detect the light emitted from the light source and passing through the optical slit. The light detecting elements for light amount monitoring have an angular width that is an integer multiple of the angular interval of the light intensity distribution on surfaces of the light detecting elements for light amount monitoring.

Optical rotary encoder

Optical encoder with reduced reflected light error having a light non-transparent portion with inclined surfaces

An optical rotary encoder for acquiring rotation information regarding a shaft includes a light source located on or in the vicinity of the axis of rotation of the shaft for emitting light rays and a code wheel mounted on the shaft for rotation about the axis of rotation. The code wheel has a plurality of alternating light transmissive and non-light transmissive areas in a circumferential direction. A reflector is spaced a distance from the code wheel for reflecting the light rays emitted from the light source so that they are turned into a parallel beam of light. The parallel beam of light illuminates the light transmissive areas of the code wheel so that light passing through the light transmissive areas is directed toward a peripheral region of the light source. The encoder also includes one or more light-detecting element for detecting the light passing through the light transmissive areas.

A photoelectric rotary encoder includes a light source that emits a light beam, a returning section that returns the emitted light beam to a direction opposite to an emitting direction of the beam, and a photodetector that is disposed on a substrate on which the light source is disposed and that detects the returned light beam via a disk having a detection pattern section. The photoelectric rotary encoder detects rotational displacement of the disk based on the detected returned light beam. In this photoelectric rotary encoder, an optical element that lets a stray beam component of the light beam from the light source escape via a side surface of the optical element, is disposed in front of the substrate on which the light source and the photodetector are disposed. The optical element covers the substrate and integrates the optical element and the substrate.

Photoelectric rotary encoder

A scale generates a periodic light-intensity distribution pattern having a pitch upon irradiation by emission light from a light source. Light-detecting element groups are shifted relative to the scale to generate phase signals having fixed phase differences. Light-detecting elements are adjacently positioned to have the same phase to form each light-detecting element group. Area centers of gravity on a phase axis of the light-detecting element groups having a fixed phase difference are made coincident with each other.

Phase-shift photoelectric encoder

An absolute-value encoder device for detecting a plurality of rotation quantities is disclosed. An A/B phase forming portion,forms an A-phase pulse signal and a B-phase pulse signal, based on light passing through a slit rotating together with a rotary shaft. One period of each of those pulse signals corresponds to one revolution of a rotary shaft. The A- and B-phase pulse signals are displaced in phase by 90&deg; from each other. When an A/B-phase state detecting portion,detects a state change of each of those pulse signals, a clock forming portion,changes a frequency of a clock pulse signal to another frequency.

Absolute-value encoder device

In a position detecting apparatus which detects an absolute position by A/D converting sinusoidal and cosinusoidal signals and performing interpolation, a phase error between the signals which is caused by movement of a detection object during the A/D conversion is corrected, thereby enabling sample hold circuits which have been necessary for maintaining the synchronism of analog signals to be omitted, so as to realize the cost reduction and miniaturization. This is enabled also in an apparatus of high resolution. Position data at requests of the last and preceding times are stored into a RAM,On the basis of the position data, a CPU,predicts the amount of a phase shift of another signal due to movement during A/D conversion of one signal, corrects the predicted phase shift amount, and then calculates the position data.

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Tokyo, Japan

Yoichi Ohmura