Abstract: Magnetic resistive elements 4 and 5 cooperatively detect the change of the magnetic field responsive to the rotation of a gear 2 fixed to a shaft 1. An amplification circuit 6 comprises an operational amplifier 7 having an input terminal to which a gain-determining input resistor 8 is connected. A gain-determining feedback resistor 9 is provided in a feedback path of the operational amplifier 7. The gain-determining resistors 8 and 9 are formed by a P well region and a P+ region of a MOS process element. The temperature characteristics of the gain-determining resistor 8 and 9 are opposed to that of the magnetic resistive elements 4 and 5. The temperature characteristics of the gain of the operational amplifier 7 cancel the temperature characteristics of the magnetic resistive elements 4 and 5.

Abstract: A rotation object is made of a magnetic material and disposed within a predetermined range of an angle of rotation on a plane perpendicular to an axis of rotation. A bias magnet generates a bias magnetic field to the rotation body in a direction perpendicular to the axis of rotation. Magnetic resistance elements are disposed in the bias magnetic field on a plane including the axis of rotation at a position deviated from the position of the rotation object in the axial direction of the rotation body and inclined by about 45.degree. relative to a direction perpendicular to the axis of rotation.

Abstract: An automatic gain control circuit for controlling the gain of an amplifier amplifying an ac signal is provided which includes a resistance circuit, a comparing circuit, a gain control determining circuit, and a gain controlling circuit. The resistance circuit includes a plurality of resistors connected in series through taps. The comparing circuit compares an output signal of the amplifier with reference upper and lower limit values to determine whether the output signal of the amplifier is within a desired amplitude range of the reference upper limit value to the reference lower limit value or not. The gain control determining circuit determines whether the output signal of the amplifier has exceeded the upper and lower limit values sequentially during a complete cycle thereof for determining whether the gain of the amplifier should be changed or not.

Abstract: A noncontact type rotation sensor, which can detect the rotational movement of a gear with high sensitivity and precision without causing any erroneous output, is disclosed. To a magnetic gear is applied a bias magnetic field by a bias magnet from the direction of the teeth of the gear. A sensor part disposed within the bias magnetic field comprises a substrate and a plurality of magneto-resistive elements mounted on the substrate in parallel to the teeth of the gear and electrically connected in series one after another. The sensor part detects the magnetic vector of the bias magnetic field varying according to the rotation of the gear as the composite value of the variations of the resistance values of the plurality of magneto-resistive elements connected in series one after another.

Abstract: Magnetoresistive elements are disposed facing a gear to form a sensor for detecting rotation of the gear. The signal output from MRE sensor is an alternating amplitude signal. An operational amplifier has a differential gain exceeding its operational limit relative to the amplitude value of the sensor signal, and it amplifies and outputs the difference between the sensor signal and a reference voltage. Comparators judge whether an output of the operational amplifier is within a predetermined amplitude range relative to the amplitude center thereof. When the op-amp output deviates from the predetermined amplitude range, transistors either charge or discharge a capacitor, so that the reference voltage can be changed closer to the output of the operational amplifier. Another comparator compares the output signal of the operational amplifier with a threshold value to output a binary-valued signal.

Abstract: In a magnetism detecting apparatus, a magnetoresistance element is positioned adjacent to a gear with teeth to be responsive to magnetic field applied thereto. The gear is shaped such that each of the teeth satisfies SA/(SA+SB)<0.125, where SA denotes a cross-sectional area of a tip portion of each of the teeth, which tip portion is measured through 10% of a height of each of the teeth taken from a tip of each of the teeth, and SB denotes a cross-sectional area of a notch portion of each notch between the teeth, which notch portion has a height corresponding to the height of the teeth. As a result of this configuration, distortion contained in an output signal based upon high and low threshhold values from the magnetoresistance element can be eliminated. In addition, variations in intervals of a pulse signal obtained by performing a waveform shaping operation can be reduced, even when a distance between the gear teeth and the magnetoresistance element is varied.

Abstract: A displacement detector to obtain high-precision displacement detection with a small-sized, low-cost apparatus. A displacement detector comprises rectangular teeth formed on the outer circumference surface at a pitch of .lambda., a gearwheel made of a magnetic material, a magnet having a width larger than the pitch .lambda. of the gearwheel and so disposed that the N-pole thereof faces the teeth, and a pair of MREs constructed by alternately connecting the long strip portions and short strip portions thereof to have a zigzag shape. A uniform cyclic magnet field from the magnet to the gearwheel is formed within a gap between the gearwheel and the magnet. On the same phase of the magnet field are disposed the pair of MREs so that the directions of the long strip portions thereof and the directions of the magnetic force lines make angles of approximately 45.degree. and approximately 135.degree., respectively.

Abstract: A magnetic detector which is small in size and is capable of preventing the occurrence of deformation in the waveform representing a change in the resistance. A bias magnet 2 is adhered to the support plate 1. A bias magnetic field is generated by the bias magnet 2 toward a gear 7. A substrate 3 is adhered onto the support plate 1, and magneto resistance elements are formed on the substrate 3 by vacuum evaporation. The magneto resistance elements are disposed in parallel with the magnetized surface of the bias magnet 2. The magneto resistance elements are disposed being tilted by about 45 degrees with respect to a vector that is in parallel with the N-pole surface of the bias magnet 2 in the bias magnetic field and is directed toward the outer peripheral edge.

Abstract: A magnetic detection device including a biasing magnet for generating a bias magnetic field directed to an object of detection having a magnetic material; a magnetoresistance effective element disposed at an inclination of about 45.degree. to the direction of the bias magnetic field to provide a change in resistance caused by the bias magnetic field in accordance with movement of the object of detection, so as to detect a change in state of the bias magnetic field via the change in resistance of the magnetoresistance effective element; and the biasing magnet having a hollow portion containing a holder for holding the magnetoresistance effective element in a position between a surface of the biasing magnet and the object of detection and close to the surface of the biasing element.

Abstract: In a physical quantity detecting device for converting a physical quantity into changes in the cycle of a pulse signal and for amplifying the cycle to convert it into digital data, detecting accuracy is improved by increasing the sampling frequency without reducing the degree of the amplification of the cycle of the signal. In a physical quantity detecting device wherein pulse signals having oscillation frequencies changing depending on the ambient strength of magnetism are output from oscillators and wherein the cycles of the pulse signals are amplified by counters and decoder portions and are input to a pulse phase difference encoding circuit to convert the phase difference into digital data, the digital data is interpolated using the pulse signal from one of the oscillators as a sampling signal. This makes it possible to interpolate the digital data to accurately detect the strength of magnetism without providing a special oscillation device for inputting a sampling signal to the interpolation circuit.

Abstract: A position detector which provides improved reference position detecting precision by stabilizing the output signal from magnetoelectric transducers in a reference position part. A rotor has a magnetized surface alternately provided with different magnetic poles and a reference positional part in which magnetic poles provided on the magnetized surface are partly omitted. A rotational angle sensor has MR elements laid out thereon in opposition to the magnetized surface of the rotor to output the voltage signal VS according to the magnetic field intensity in the magnetized surface due to the rotation of the rotor. A waveform processing circuit and a pulse signal processing signal shape the waveform of the voltage signal from the rotational angle sensor, and also generate the rotational angle pulse signal and a reference position pulse signal according to the waveform reforming signal.

Abstract: An image sensor can reduce fixed pattern noise (FPN) caused by transistors used for reading pixel signals. The image sensor comprises photodiodes D.sub.1, D.sub.2, . . . connected to a precharge line L.sub.PR through respective precharge transistors (Tr1).sub.1, (Tr1).sub.2 ; and pixel amplification transistors (Tr2).sub.1, (Tr2).sub.2, . . . , one end thereof being connected to a signal read line L.sub.RE, the other end thereof being grounded through respective pixel switching transistors (Tr3).sub.1, (Tr3).sub.2, . . . , and the gates thereof being connected to respective nodes between the precharge transistors Tr1, (Tr1).sub.2, . . . and the photodiodes D.sub.1, D.sub.2, . . . According to signals provided by a timing signal generator 3, the pixel switching transistors (Tr3).sub.1, (Tr3).sub.2, . . . are sequentially turned ON and OFF one after another.

Abstract: An apparatus for optically detecting the attachment state of extraneous matters to a translucent shield member. The optically detecting apparatus comprises a light-emitting unit having a plurality of light-emitting elements each emitting a light ray toward the translucent shield member, a photoelectric transducer unit having a plurality of transducer elements each receiving each of the light rays reflected on the translucent shield member, and a data processing unit coupled to the transducer unit. The transducer unit generates detection signals corresponding to the quantities of the received light rays and the data processing unit successively compares the level of each of the detection signals with a predetermined level to produce binary signals in accordance with the results of the comparison so that a binary signal pattern is defined at the respective transducer elements.