Abstract: A disc recording and/or reproducing apparatus has a scale movable along with a magnetic head radially of a magnetic disc provided in the disc recording and/reproducing apparatus and which has recorded thereon readable by a laser light position information indicative of the radially moving position of the magnetic head. The position information indicates a smaller range than the radial length of a signal recording area on the magnetic disc. The writing of servo signals to the magnetic disc is done by a servo signal writing apparatus including an optical head disposed movably in a position corresponding to the moving position of the scale to detect the position information recorded on the scale, and a main controller to move the magnetic head radially of the magnetic disc for writing the servo signal to the magnetic disc and to move the optical head correspondingly to a position where the servo signal is to be written.

Abstract: In a position transducer having detection coils 11 and 21, auxiliary coils 12 and 22 are driven in phase with the detection coils 11 and 21 and are lap-wound on the ends of the detection coils to substantially increase the winding density at the ends of the detection coils 11 and 21, thereby reducing the magnetic field non-linearity at the coil ends.

Abstract: A position transducer in which a carriage 32 and slider 33 are coupled to each other by tension coil springs 41A and 41B each having an elasticity in a direction in which the carriage 32 and slider 33 are attracted towards each other, with the carriage 32 and slider 33 being butted to each other with a rolling bearing placed at one end of the carriage 33 in the moving direction and which has a ball 40 held by a plane bearing 37 and conical bearing 39.

Abstract: A position transducer including a scale and magnetic sensor system consisting of a first sensor unit and second sensor unit disposed in different positions in a direction (Z-direction) perpendicular to a moving direction (X-direction) of the magnetic sensor relative to the scale. The first and second sensor units are driven in phase with each other with a high frequency signal, and a difference between outputs of these two sensor units is determined in order to detect a relative position of the magnetic sensor to the scale.

Abstract: For effecting auto-focussing of an objective lens used for observing a semiconductor wafer, a semiconductor microscopic device includes an inspection stage for supporting a semiconductor wafer and an objective lens for observing the semiconductor wafer. For automatic focussing of the objective lens, a defocussing magnitude of a light spot is detected using a knife edge. A collimator lens is oscillated by a voice coil motor to oscillate the light spot on the wafer. A peak value of the defocussing quantity detected at this time is peak-held to generate a position detection signal. The inspection stage is vertically moved so that this position detection signal will be equal to a pre-set target value.

Abstract: A position transducer includes a bias circuit that drives and controls first and second bias coils. The bias circuit monitors the value of a voltage produced in a second sensor coil and drives and controls the first and second bias coils such that the value of the voltage produced in the second sensor coil is always equal to a desired voltage value.

Abstract: A sensor coil is provided on a core which forms a magnetic circuit for driving a linear motor, and the core is excited by electrifying the sensor coil at a high frequency. The high-frequency excitation is carried out in such a manner that the sensor coil is not magnetically saturated, and an eddy current is generated in the core. The impedance of the sensor coil is detected in this state and the quantity of a magnetic flux generated in the core constituting the magnetic circuit is detected on the basis of the impedance. Thus, the influence on the magnetic circuit itself is reduced and higher accuracy, miniaturization and lower power consumption are realized.

Abstract: A stable signal is output in which when there is no movement, unstable output change does not occur, and an output change exceeding a predetermined limit does not occur. The variation &Dgr;PH in the output angle signal PH to be output is subjected to hysteresis and through rate limitations with respect to the variation APF in the input angle signal input thereto. When the variation APF in the input signal is in a hysteresis range of −Hys<&Dgr;PF<+Hys, the variation in the output angle signal is output as 0. When the variation &Dgr;PF in the input signal is in a hysteresis range of &Dgr;PF<−(Hys+SR) or &Dgr;PF>(Hys+SR), a through rate limitation is effected to thereby clip the variation in the output angle signal to SR. When the variation &Dgr;PF is in other regions, the output follows the input linearly with the output delayed by the hysteresis quantity.

Abstract: A position detector detects the position of a detector section relative to a record medium having recorded thereon a periodic position signal. The detector section has two detectors that produce first and second detection signals that are polar converted and processed, based on the number of divisions in a quadrant of the periodic position signal.

Abstract: A dew formation occurrence detection apparatus for detecting the dew formation on a drum 4 of a tape transport system provided on the electronic equipment 1 as an object for measurement. The dew formation occurrence detection apparatus includes a drum temperature detection unit 8 for detecting the temperature of the drum 4, an environment air temperature acquisition unit 6 for acquiring the environment air temperature of the electrical equipment 1 and a dew point temperature calculating unit 6 for calculating, from this environment air temperature, the dew point temperature at the humidity which takes the operating environment of the electronic equipment 1 into account. When the temperature of the drum 4 is not higher than this dew point temperature, it is verified that dew formation has occurred.

Abstract: An optical displacement measurement system that can detect the position of an object with an enhanced degree of resolution, wherein a coherent beam La is focussed on the lattice plane of a diffraction grating and, at the same time, a diffracted beam Lb is focussed on the light receiving plane of a light receiving means 3. The length of the optical path of any diffracted laser beam that passes through the aperture of a second focussing means 5 remains invariable. Therefore, if the optical axis of the diffracted beam Lb is deviated, the spot where it is focussed on the light receiving plane of the light receiving means 3 is not shifted and hence the length of the optical path will not change. Two diffracted laser beams having in equal length of optical path are made to interfere with each other in order to detect the phase difference. The displaced postion of the diffraction grating coherent beam La1 is then measured on the basis of the phase difference.

Abstract: A position detecting apparatus including a magnetic scale and a magnetic sensor for detecting a magnetic field generated by the magnetic sensor. The magnetic field extending in a magnetism-sensing direction perpendicular to a first direction in which the magnetic sensor moves relative to the magnetic scale and a second direction in which the magnetic sensor is spaced from the magnetic scale. The positional relationship between the magnetic scale and the magnetic sensor is detected from the magnetic field detected by the magnetic sensor in the magnetism-sensing direction.

Abstract: A magnetic metal sensor having a high response speed and which can detect small-sized metal pieces and can elongate the separation from the metal pieces. A magnetic metal sensor 2 has a core 22 defining a substantially U-shaped open magnetic path and coils 23, 24 of the same polarity mounted on the core 22. A uniform magnetic field along the direction of magnetic sensitivity is applied by a magnet 25 across the coils 24, 24. If magnetic metal approaches to a open magnetic path portion of the core 22 of the magnetic metal sensor 2, the magnetic reluctance of the magnetic circuit formed by the core and air is changed, as a result of which the impedance of the cores 23, 24 is changed. The magnetic metal sensor 2 detects the possible presence of magnetic metal or its displacement based on impedance changes of the paired coils 23, 24.

Abstract: A magneto-resistive effect sensor capable of outputting a sufficient output of optimum characteristics even if a magnetized surface of a magnetized material is curved, arcuately- or polygonally-shaped. On the magneto-resistive effect sensor 3, plural magnetically sensitive portions 12a to 12d of the same shape are formed and arrayed parallel to one another, while being electrically connected in series to permit the current i to flow through the electrically connected magnetically sensitive portions. The magnetically sensitive portion 12a is made up of a mid portion 15a having a width w1 and ends having a width w2. A signal magnetic field of different strengths is applied from the magnetized material along the current flowing direction. The widths w1 and w2 differ with the strengths of the applied signal magnetic field and are of a ratio such that w1:w2=2:3.

Abstract: A recording system such as a magnetic tape data recording and reproducing system is arranged to record data management information to three different storage devices. The recording system records management information on a record medium such as a tape, a cassette memory built in a tape cassette and a recorder memory of the recording system. A control section of the recording system first reads the management information from the cassette memory, further reads the management information from the recorder memory if the management information of the cassette memory is insufficient, and finally reads the management information from the record medium if the management information of the recorder memory is still insufficient.

Abstract: An optical displacement measurement system can detect a position of an object with an enhanced degree of resolution by providing, a coherent beam La is focussed on the lattice plane of a diffraction grating 1 by a first focussing element 4 and, at the same time, a first pair of diffracted beam Lb1, Lb2 are collimated and made to irradiate a reflection optical system 3 perpendicularly by a second focussing element 5. Thus, if the optical axis of the first diffracted beam Lb1 is displaced, the first diffracted beam Lb1 follows the same optical path and focussed on the lattice plane of the diffraction grating at the same spot when reflected by the reflection optical system so that the optical axis of the second diffracted beam Lb2 produced from the first diffracted beam Lb1 as the latter is diffracted will never be displaced.

Abstract: The present invention provides a position detection apparatus capable of reducing the bending moment in the longitudinal direction of a recording medium and being fixed to a machine tool without deforming the main body or the recording medium, thus enabling to obtain a high detection accuracy. The position detection apparatus detects a relative movement position between the reference block 4 and the movable block which move relative to each other along straight line. A round bar-shaped recording medium 12 is provided inside a frame 11 of a main body 2. The frame 11 is fixed to the reference block 4 with a fixing member 55 having an abutment surface for the frame 11 which abutment surface has a curvature only in a direction parallel to the longitudinal direction of the recording medium.

Abstract: The present invention provides a position detection apparatus capable of suppressing a crosstalk between a scale signal and an origin signal and detecting a position with a high accuracy. A recording medium 12 of a round bar shape has a magnetic signal alternately reversing the polarity at a predetermined recording wavelength .lambda..sub.1 and recorded as a scale signal in the longitudinal direction of the recording medium 12. This scale signal is recorded over the entire outer circumferential surface of the recording medium 12 and almost over the entire length of the recording medium 12. Moreover, the recording medium 12 has a one-wavelength origin signal of recording wavelength .lambda..sub.2 recorded at least at one position over the scale signal. The recording wavelength .lambda..sub.2 of this origin signal is longer than the recording wavelength .lambda..sub.1 of the scale signal. The origin signal is recorded at a part of the outer circumference.

Abstract: The displacement measuring apparatus of a laser interference technology includes a probe 3 which delivers at a photodetector 17 an RF signal of which a modulated component proportional to a displacement of an object 2 under measurement. The apparatus has also a phase-demodulation circuit 9 in which an interference signal produced by shifting the frequency of the RF signal to an intermediate frequency is phase-demodulated on the basis of the carrier signal for supply to a light modulator 16. Thus the apparatus can detect a displacement of the object with a high resolution.

Abstract: A scale device 1 includes a base unit 2 comprised of an elongated casing 3 wherein an elongated thin-plate-like scale 4 is secured with the a mid portion of the thin-plate-like scale 4 kept in a floating state and a slider unit 10 slidable relative to the base unit 2. The slider unit 10 has a sensor 15 for detecting magnetic graduations recorded on the thin-plate-like scale 4. A reference sliding member 16 is provided for maintaining a constant separation between the sensor 15 and the recording surface of the magnetic graduations of the thin-plate-like scale 4. A pressing sliding member 17 is provided for pressing the reference sliding member 16 so that the recording surface of the magnetic graduations are perpetually contacted with the reference sliding member 16. A detection head unit 14 is movable telescopically relative to the thin-plate-like scale 4 in a direction along the width of the scale.