Tdk Corporation

Teiichiro Oka

Hiroyuki Hirano

Makoto Takahashi

Mikio Sumiyoshi

Yosuke Antoku

Giichi Shibuya

Ryoichi Menju

Yoshinori Sato

Koji Mishima

Kenji Yamaga

Daisuke Yoshitoku

Seiji Fukuoka

A magnetic field detection device includes a magnetic field generation unit that generates a magnetic field, a magnetic field detection unit that detects the magnetic field, a first housing that has an accommodation unit that accommodates the magnetic field detection unit so that the magnetic field detection unit is exposed, and a second housing that movably accommodates a moving body. The strength or angle of the magnetic field generated from the magnetic field generation unit and applied to the magnetic field detection unit changes in accordance with movement of the moving body. The second housing has a mounting unit on which the first housing is mounted. The first housing is mounted on the mounting unit via a seal member that surrounds the magnetic field detection unit, so that the mounting unit is between the magnetic field detection unit and the moving body, and the inside of the accommodation unit is sealed by the seal member and the mounting unit.

Magnetic field detection device, magnetic sensor module, magnetic control device, motor and transmission

A position detection apparatus includes a magnetic unit and a sensor. The magnetic unit includes a magnetic member and a retainer. The magnetic member includes a magnet and a first magnetic yoke. The magnet extends in an axial direction and has a cross-section orthogonal to the axial direction, and a first maximum outer diameter in a radial direction orthogonal to the axial direction. The cross-section has a substantially constant area in the axial direction. The first magnetic yoke is disposed adjacent to the magnet in the axial direction and has a second maximum outer diameter in the radial direction. The second maximum outer diameter is greater than the first maximum outer diameter. The retainer extends in the axial direction and retains the magnetic member. The sensor detects a magnetic field that changes in association with a movement of the magnetic unit along the axial direction.

Magnetic unit, position detection apparatus, and magnetic member

A current sensor that is less affected by the residual magnetization is provided. A current sensor of the present invention has a magnetic circuit that is magnetized by electric current; a first magnetic field detecting element that is positioned where a magnetic field, when the electric current is present, is directed in a same direction as a magnetic field that is caused by residual magnetization of the magnetic circuit when the electric current is not present; and a second magnetic field detecting element that is positioned where a magnetic field, when the electric current is present, is directed opposite to a direction of a magnetic field that is caused by residual magnetization of the magnetic circuit when the electric current is not present.

Current sensor

A rotational angle detection device includes a magnet with n pole pairs (where n&#x2265;3) provided to be integrally rotatable with a rotating body; magnetic detection parts including first and second magnetic detection parts; a corrected signal generation part generating first and second corrected signals; and a rotational angle detection part detecting the rotational angle of the rotating body based on the first and second corrected signals. The waveform of the first and second detection signals have a phase difference of 90&#xb0; from each other. The corrected signal generation part adds the first sensor signals and adds the second sensor signals. The region at the perimeter of the magnet includes first through nth regions, and at least two of the first and second magnetic sensor parts are positioned in different regions from each other among the first through nth regions.

Rotational angle detection device

A sensor is provided with a magnetic detection element that can output an output voltage within a predetermined voltage range according to a magnetic field intensity, an output voltage fixing part that can fix a voltage value of the output voltage to a voltage value outside the voltage range, and a drive voltage output part that can output a drive voltage for driving the output voltage fixing part. The drive voltage fixing part outputs the drive voltage to the output voltage fixing part when the ambient temperature of the drive voltage output part exceeds a predetermined threshold, and when triggered by input of the drive voltage, the output voltage fixing part fixes the voltage value of the output voltage to a voltage value outside the voltage range.

Sensor for detecting temperatures

A position detection system includes a first magnet, a first soft ferromagnetic member, and a magnetic detector. The first magnet is magnetized in a first direction and generates a first magnetic field including a first magnetic line. The first soft ferromagnetic member is rectilinearly movable along a second direction and includes a first outer edge having a first outer edge part remote from the first magnet by a first distance in a third direction and a second outer edge part remote from the first magnet by a second distance in the third direction. The first and second outer edge parts are disposed at different positions in the second direction. The magnetic detector is kept at a predetermined constant position relative to the first magnet. The first magnetic line passes through the magnetic detector in the first direction when the first soft ferromagnetic member is at rest.

Position detection system

A sensor intermediate part is provided with a physical quantity detection element that has a power source terminal, a ground terminal and an output terminal that outputs a desired output signal, where the physical quantity detection element is capable of adjusting properties of the output signal; a high-capacitance capacitor, which has at least a first terminal and a second terminal, and a jumper wire, one end of which is conducted to either the power source terminal or the second terminal and the other end of which is not conducted. The first terminal is conducted to the ground terminal, and the power source terminal and the second terminal are configured to be electrically connectable by the jumper wire.

Sensor intermediate part, sensor and sensor manufacturing method

An optical head, capable of performing output control for a light source without weakening an intensity of a light beam for recording and reproduction even if an optical element is not added anew, and an optical recording and reproducing apparatus including the optical head. Light fluxes near the center of an optical beam emitted from a light source are made incident on a diffractive element and transmitted through a beam splitter or the like to be irradiated on an optical recording medium. On the other hand, a part of peripheral light fluxes of the light beam are reflected in a direction substantially perpendicular to an optical axis by a reflection surface of a holder provided at an end of the diffractive element. Light beams reflected on the reflection surface are made incident on a photo-detector, and the photo-detector converts the light beams into an electric signal for output monitor of the light source according to an amount of received light. This electric signal for output monitor is fed back to a drive circuit of the light source to thereby perform control for an output of the light source.

Optical head, optical reproducing apparatus, and optical recording and reproducing apparatus

Beams of light emitted from a light source are incident on a polarizer. The direction of a transmission axis of the polarizer can be adjusted in advance such that the polarizer transmits P polarized light, and S polarized light is attenuated. Beams of light transmitted through a diffracting device and a collimator lens for incidence on a beam splitter are made up substantially only by P polarized light. Part of the beams of light, which is reflected on the beam splitter, is incident on a photodetector for feedback control of outputs from the light source. Since S polarized light is attenuated by the polarizer, only P polarized light is incident on the photodetector. Consequently, if the quantity of emitted laser beams changes, a ratio between the quantity of light for record and reproduction and the quantity of light for APC remains substantially constant, thereby increasing accuracy of detecting the intensity of laser beams, to avoid errors in record and reproduction.

Optical head, optical reproduction apparatus and optical record and reproduction apparatus

The invention relates to a light-receiving element for receiving a reflection of laser light irradiated to a rotating multi-layer recording medium having a plurality of information recording layers stacked one over another and for converting the light into an electrical signal, an optical head having the element for recording information in the multi-layer recording medium or reproducing information recorded therein, and an optical recording/reproducing apparatus and a method of optical recording and reproduction. The invention provides a light-receiving element, an optical head, an optical recording/reproducing apparatus, and a method of optical recording and reproduction which make it possible to eliminate a noise component superimposed on reflected light from a multi-layer recording medium to reproduce an RF signal of high quality. The light receiving element receives a reflection of laser light irradiated through an objective lens to a rotating multi-layer recording medium having a plurality of information recording layers stacked one over another through a return path optical system and converts the reflected light into an electrical signal. The element has a first light-receiving section having a circular light-receiving region and a second light-receiving section disposed adjacent to the outer circumference of the first light-receiving section in the form of a circle concentric therewith.

Light-receiving element, optical head, optical recording/reproducing apparatus, and method of optical recording and reproduction

To provide a light receiving device, a light detecting device, and an optical signal reproducing device each of which allows one to perform many different computations in detecting aberration amounts and focus error quantities without requiring exact position relations between laser light to be received and light receiving elements, and between the light receiving elements. First and second light receiving elementsandare used which receive condensed light at positions equidistantly spaced from an focal point X before and after the light images, respectively.

Growing community of inventors

Tokyo, Japan

Teiichiro Oka