Abstract: A circuit configuration for editing, or processing the output signal of a speed sensor (5) includes a trigger circuit (1, 22), the changeover points or "hysteresis" of which are controllable, with the circuit configuration being furnished with circuits for determining the coupling factor (k), and with circuits for adjusting the hysteresis in response to the coupling factor. The coupling factor (k)--multiplied by the frequency of the sensor signal corresponding to the speed--forms the amplitude of the sensor output signal. With the coupling factor (k) being high, the hysteresis will be high, while it will be low with a low coupling factor.

Abstract: A sensor generates a pulse signal at a predetermined angle of a rotating body. First and second registers respectively memorize both of a leading edge and a trailing edge of a divided signal of the pulse signal. The first resistor maintains the timing of the detected preceding leading edge until the next leading edge is detected so that the timing of the next leading edge is renewed when the next leading edge is detected. The second register maintains and renews the timing of the trailing edge in the same manner as the first register. The rotational speed is obtained by computing the time difference of each memorized timing at the start of such computing operation. Accordingly, an accurate rotational speed can be always obtained, even when the rotational speed computing operation is delayed by a high priority interrupt operation.

Abstract: A method of determining the direction of rotation of a member (17) is closed, wherein the member has a speed pick-up rotor (27) having a plurality of teeth or exciter surfaces (29). The rotor has a predetermined pattern of gaps (37,73) and groups of teeth, each group of teeth having a number of teeth which is different than the number in any other group. As the rotor rotates, the pattern of gaps and teeth is sensed, and compared to a predetermined pattern. Depending upon the results of the comparison, the logic generates either a signal (61) representing clockwise rotation, or a signal (65) representing counter-clockwise rotation.

Abstract: A speed detector device capable of making speed measurements of an elevator in its relatively slow speed region comprises a pulse generator generating two-phase pulse signals with a predetermined phase difference between both signals, in a period according to the rotational speed of a motor, a pulse processing circuit for outputting corresponding triggers in response to the rising edge and the falling edge of each of the pulse signals generated by the pulse generator, a timer counter, latches for latching the output of the timer counter at the timing of the triggers, and calculating circuit for calculating the period of the pulse signals based on the timer counter output and for calculating the speed of the elevator based on the period calculated. The above arrangement allows data to be latched not only at the rising edge of the one pulse signal, but also at the falling edge of the same pulse signal and the rising and falling edges of the other pulse.

Abstract: A processing circuit for a magnetoresistive rotary speed sensor (13) or the like having a comparator (11) with switching hysteresis for converting an analog sensor signal into a digital switching signal. An apparatus is provided at the input side of the comparator in order to alternately supply each of the comparator inputs, as a function of the switching signal at the output side of the comparator, symmetrically with a given hysteresis signal as a switching threshold. This apparatus also includes a preamplifier (15) which precedes the comparator non-inverting input and which amplifies the sensor signal, and an offset amplifier (18) of the same construction which precedes the comparator inverting input and which amplifiers an offset signal of a preceding offset network (21). The processing circuit provides a simple, integrable circuit which suppresses offsets and compensates for temperature and supply voltage fluctuations and any spread in tolerances of the circuit components.

Abstract: A vehicle speed measuring method and apparatus which can cope accurately with several vehicle speed sensors which produce different numbers of pulses for one rotation. Such vehicle speed sensors prepared for the method and apparatus produce predetermined different numbers of pulses for one rotation, some of such sensors defining a group wherein such numbers of pulses have a greatest common divisor greater than 1. It is first determined whether or not a particular vehicle speed sensor employed belongs to this group of sensors. When the sensor belongs to the group, pulses therefrom are frequency divided by a value obtained by division of the number of pulses produced for one rotation of the sensor by the greatest common divisor, and time data indicative of the time of appearance of a pulse by frequency division are stored into a memory for one rotation of the sensor.

Abstract: A centrifuge rotor overspeed protection system which can operate with rotors of at least two speed ranges. A set of coding elements are provided on the rotors coded to represent the actual maximum safe speed rating of the rotor. An additional set of coding elements coded to correspond to the maximum speed in the lower speed range are also provided such that the rotor can be operated at the maximum speed possible in a prior art centrifuge designed for operation in the lower speed range. The detection circuit for the coding elements automatically adjusts the detection threshold depending on the average values of the sensor output peaks corresponding to the codes.

Abstract: A meter driving system receives pulse signals from a sensor, counting frequencies or periods of the input signals. The counted results are weight-averaged to determine an output value and a value to be indicated. In a weight-averaging process, a weight is varied in response to the frequencies of the input signal. Thus, the meter can give a precise indication regardless of varying input frequencies.

Abstract: A circuit for producing a display indicative of a bicycle rider's pedaling technique. The circuit measures the time required for the pedals to move through a given angle of rotation. The circuit then calculates the relative pedal velocity over the angle of rotation. This process is repeated over an entire circle of rotation to determine the variations in pedal velocity as the pedal moves through a full circle. Since the pedal velocity is related to the pedaling force applied by the rider, the variations in pedaling force can be determined. Further, the circuit has a display unit which shows a rotating line of varying length to indicate the pedaling force applied as the pedals move respectively through a full circle.

Abstract: The rotation detecting device comprises m proximity detectors for detecting the passage of a mark fixed to a rotary element. Changes in the signals delivered by each of the detectors in a selected series of m-1 detectors are analyzed. Once a mark is detected at one of the sectors situated at an end of the series, a revolution counting index is incremented, a new series of m-1 detectors is selected excluding the detector which has just detected the passage of the mark, and criteria representative of changes in the signals are reinitialized for the forthcoming signals from the newly-selected series. An adaptive system is thus obtained applicable to detecting the rotation of a spinner in a water meter.

Abstract: A wireless velocity detector for a bicycle includes a coil mounted on the wheel hub of the bicycle which generates a rotating magnetic field as the wheel rotates, a receiver mounted on the handlebars that includes a pair of coils that sense variations in the strength of the rotating field as the bicycle moves and generates signals in response to the field variations and a microprocessor which converts the signals into information related to the movement of the bicycle, e.g. speed and distance. A liquid crystal display is used to display the information to the cyclist.

Abstract: A bearing apparatus is capable of detecting rotational speed of a driven shaft of an automobile. The bearing apparatus has a rotational speed detector and a detected member. The detected member is fixed to an inside member rotating with the driven shaft. The detected member has a hollow cylindrical portion which extends in an axial direction and is provided with a plurality of projections at even intervals in a circumferential direction on its inner peripheral surface. The rotational speed detector is fixed to a cover for covering the rotational speed detector and the detected member. A detector portion of the rotational speed detector is positioned within the hollow cylindrical portion so as to oppose the projections.This is a divisional application of application Ser. No. 07/626,311, filed on Dec. 13, 1990, now abandoned which is a continuation application of now abandoned application Ser. No. 07/469,183, filed on Jan. 24, 1990.

Abstract: A method and apparatus for measuring a motor speed in which a measurement pulse train is formed from a measurement signal generated in a frequency generator coupled to the rotation of a motor, and a reference pulse train is formed with a frequency greater than that of the measurement pulse train, and the number of both pulses are counted for a predetermined sampling time, and both count values are compared, thereby measuring the motor speed. Accordingly, the rotation speed can be measured by a single algorithm regardless of the variation of the motor speed, and the measurement time and the measurement error can be greatly decreased. Furthermore, the continuous speed controlling over the whole speed range is possible.

Abstract: A speed sensor tone wheel has a plurality of serrations formed on an inner periphery for engagement with an axially extending annular surface formed on a wheel bearing seal support. The tone wheel is mounted on the support and an outwardly facing surface of the serrations is coined to force the inner ends of the serrations into contact with the annular surface to prevent relative rotation between the tone wheel and the support. Tabs can be formed in the outer periphery of a radially outwardly extending flange of the wheel bearing seal support for extending through open spaces between the serrations and engaging a surface of the tone wheel to trap the tone wheel between the support flange and the tab. Alternatively, an indentation can be formed in the flange to project into an associated one of the serrations.

Abstract: In the revolution frequency indication apparatus in which the revolution frequency of a rotating body is measured and indicated according to a sensor pulse obtained from a revolution sensor mounted on said rotating body or its surrounding, a revolution frequency indication apparatus comprising an indication updating time counter circuit which counts predetermined indication updating time intervals, and a revolution frequency measurement portion which measures the revolution frequency of said rotating body by means of a sensor pulse entered within a measurement time interval of said counter circuit.

Abstract: An RF oscillator induces eddy currents to be measured in an object. An eddy current probe senses alterations, such as teeth on a disc, for example, in the object which are represented as eddy current signals sensed by an eddy current probe. The present invention separates alteration current signals from offset currents in the eddy current signal to aid in discriminating levels in the alteration current signals. The alteration currents are separated from the offset currents by AC coupling with a high pass filter or separated by a microprocessor as part of a data processing detection routine.

Abstract: Synchronization pulses for an internal combustion engine are generated by identifying the second of two consecutive pulses of the same polarity in a pulse train of positive going and negative going pulses. An evaluation pulse sequence is generated which switches from a low level to a high level in response to a positive going pulse and from the high level to a low level in response to a negative going pulse. A synchronization pulse is generated in response to a differentiated pulse derived from the pulse train when the level of the evaluation pulse sequence indicates that a switching pulse of said same polarity as that of the differentiated pulse has just occurred.

Abstract: A circuit for controlling a ratio meter, the circuit having an input stage for generating a digital signal representative of a parameter to be displayed, memory to enable the digital signal to be encoded on the basis of a pre-defined sine, cosine, or tangent function, with the memory being addressed by intermediate significant bits in the digital signal, and an interpolator for correcting the signal from the memory on the basis of the least significant bits of the digital signal.

Abstract: An apparatus for detecting speed sensor failure in an overspeed protection device is disclosed. The apparatus comprises a plurality of tachometers having outputs for indicating the speed of rotation of a machine relative to plural setpoints. If the comparison indicates that certain conditions exist, then a sensor failue is indicated. The apparatus may also be employed to detect a failure of, or loss of power to or within, one of the tachometers.

Abstract: A pulse control circuit generates latch signals in response to edges of externally-input pulses and generates a resetting signal after each of the latch signals is generated. A pulse position measurement counter counts reference clock signals, thereby measuring the time interval between the generation of one latch signal and the generation of the succeeding latch signal. In response to the latch signal, a latch circuit latches the time interval measured by the pulse position measurement counter as output data. A pulse detector detects that the time interval between successive latch signals is shorter than a predetermined time. It also detects that the number of latch signals which have been input is larger than a predetermined number. A data control circuit is employed in association with the pulse detector.

Abstract: Two embodiments of tachometers for engines that are capable of use with an engine that either has an external source of electrical power such as a battery or no external source of power. In one embodiment, the switching is accomplished manually and in another embodiment the switching is accomplished automatically whenever battery power is applied to the tachometer. A constant voltage system reduces noise generated by this system.

Abstract: A travel detecting apparatus is disclosed which generates a pulse signal in response to vehicle motion and detects the actual rate of vehicle travel in accordance with the pulse signal. The apparatus comprises a speed or RPM sensor coupled to an automotive transmission for generating a first pulse signal representative of the vehicle speed or RPM, a tire-size setting switch for setting tire information relating to the dimensions of the tires of the vehicle, and a CPU for frequency converting the first pulse signal in response to the tire information to generate a second pulse and for detecting the rate of vehicle travel in accordance with the second pulse signal.

Abstract: A photo-optical coupler is connected to a shaft to provide a series of electronic pulses at a frequency corresponding to rotational velocity of the shaft. Apparatus electronics is responsive to frequency of such pulses for indicating a low speed alarm condition when such frequency is below a preselected threshold. The apparatus electronics includes a digital counter that is set to a first preselected count upon occurrence of each of the shaft rotation pulses, and which is thereafter decremented between the shaft rotation pulses. A low speed alarm condition is indicated if the counter reaches a count of zero prior to a succeeding shaft rotation pulse. In the preferred embodiment, the counter is decremented by an oscillator having a clock frequency coordinated with the first preselected count so as to activate the alarm when rotational velocity of the shaft decreases to a predetermined threshold percentage of a nominal rotational velocity of the shaft.

Abstract: A circuit for determining the speed of rotation of a wheel, has an inductive transmitter (1), the output of which is connected to a pulse-shaping device (7) whose output is connected to an evaluation device. The inductive transmitter is connected to an evaluation circuit (11) by means of a cable (6). The evaluation circuit is intended, on the one hand, to make certain that the input signal of the inductive transmitter (1) can be evaluated while, on the other hand, it should be able to detect errors which may occur, for instance due to a break in the cable (6) despite the presence of dirt resistances (R.sub.S). For this purpose, an auxiliary circuit (10) is provided which varies the internal resistance of the pulse-shaping device (7) as a function of the speed.

Abstract: The control method/system for sensing "tooth or pulse drop-out" type faults in the output signals from a rotational speed sensor assembly (10) of the type utilizing a rotor (12) and a relatively fixed sensor (16) to provide an output comprising a plurality of pulses having a frequency indicative of the rotational speed of the rotor is provided.

Abstract: A device for displaying a physical measure, including a reference pulse generator, a pulse counter, a memory for storing a measurement number, a second memory for storing values used for adjusting the count of pulses, a display for showing a physically measured value corresponding to the number of counted pulses, and a processing unit. The device updates the display value in accordance with pulse counts and the stored measurement number until the device detects that a correction has to be made from examining the contents of the second memory. Upon detection, the device makes proper corrections to the display values.

Abstract: A technique for reducing the effects of aliasing in a frequency output sensor system. The system includes a sensor for producing a sensor output signal at a frequency that varies within a modulation range as a function of an input parameter. The system also includes a processor for measuring the frequency of the sensor output signal at a sequence of sample times. The invention provides an analog filter for filtering the sensor output signal. In a first embodiment, the filter has an increasing phase lag versus frequency characteristic within the modulation range. In a second embodiment, the filter comprises a phase lock loop having frequency dividers in the input signal path and in the feedback path.

Abstract: A sensor magnet mounting device according to the present invention is a device which is attached to a spoke of a rotating wheel and is used for mounting a magnet applying a signal for each revolution of the rotating wheel to a sensor fixed to a frame of a vehicle. This device includes: a magnet housing containing a magnet therein and having a contact surface in contact with the spoke; at least a pair of projecting members constituting a cylindrical portion projecting to hold the spoke with a thread being formed on the inner wall of each of the projecting members; a ring engaging with the projecting members and detachable therefrom; and a set screw engaging with the threads of the projecting members. When the set screw is tightened with the ring being attached, the head of the set screw enables the ring to move toward the magnet housing so that the bottom of the ring presses against the spoke.

Abstract: A circuit configuration for contactless detection of the rpm of a rotating gear wheel includes two identical firmly mounted and magnetically prestressed Hall sensors being mutually spaced apart by a center distance equal to one-half the tooth pitch of a gear wheel whose rpm is to be detected. Each of the Hall sensors includes at least one pair of identical Hall generators having signal paths and being driven with an impressed control current or impressed control voltage. Voltage/current converters are each coupled to the signal path of a respective one of the Hall generators and each have an output. An evaluation circuit links together the outputs of the voltage/current converters connected to one of the Hall sensors and the outputs of the voltage/current converters connected to the other of the Hall sensors in phase opposition.

Abstract: A rotational speed detector for an internal combustion engine comprises a waveform processor for eliminating pulses generated within a predetermined period of time after a certain pulse appears and a measuring circuit for measuring a rotational speed based on outputs from the waveform processor. The waveform processor of the rotational speed detector thus eliminates the effects of such an unexpected pulse generated, for example, by the vibration of the ignition coil for the engine. Consequently, the measuring means detects the rotational speed accurately without measuring the unexpected pulse.

Abstract: A laser light tachometer for measuring the rotational speed of a selected rotating body without making physical contact with that body. The laser technology art is used to provide a beam of light, visible even under extremely bright ambient light conditions, to be used to measure the rotational speed of a rotating device from greater distances than previously possible. A diverging beam of laser light is collimated and transmitted to a rotating body the RPM of which is to be measured. The rotating body modulates the beam and reflects it back to the tachometer where it is focused onto a photodetector, which converts it into an electrical signal representative of the speed of the rotating body. Provisions are made for direct digital readout and for supplying the signal to other devices.

Abstract: A system for determining the position of movable machine parts including an incremental pulse generator for generating angular-speed pulses includes a computer. At least one counting circuit via which the incremental pulse generator is connected to the computer counts the generated angular-speed pulses.

Abstract: For measuring the rotational speed of a wheel is an antilocking protected vehicle brake system a rotational speed sensor is provided in which in accordance with the rotational speed of the wheel signals are electromagnetically induced which have an amplitude and frequency which increase regularly with the rotational speed. When due to error sources the amplitude of the induced signal does not increase with the frequency of the signal a rotational speed measured value is determined by means of the measured amplitude, i.e. not on the basis of the measured frequency. To avoid erroneous measuring signals it may likewise be provided that when the amplitude of the signal does not increase with its frequency the last measured value of the frequency of the induced signal at which the amplitude still increased with the frequency is used to determine the speed of rotation.

Abstract: Sine wave signals generated from a position detector are used as analog values to detect a fine position of a rotating or moving body, a rise or fall edge of the sine wave signal is used to detect a coarse position of the rotating or moving body, and the position or speed of the rotating or moving body is detected based on a signal indicative of the detected coarse position when the rotating or moving body is at high speed and based on a signal indicative of the detected fine position when the rotating or moving body is at low speed to thereby provide optimal control from high speed to low speed. Especially at extremely low driving, speed detection with superhigh resolution is effected using the analog value to decrease an uneven rotation of the rotating body.

Abstract: A meter driving apparatus used for automotive meters such as a tachometer and a speedometer. The frequency of a pulse signal the period of which changes in correspondence with an input is calculated by counting the reference clock signals. A current corresponding to the calculated frequency is applied to two exciting coils which are orthogonal to each other, and the indicator points at the direction at the angle determined by the torque received in accordance with the magnetic field generated. A time counter adds one to the current count value whenever a predetermined time has elapsed. Even when the input pulse signal has a low frequency and the frequency rapidly changes from a high value to a low value, a temporary output is calculated from the current count value so as to prevent the degradation of the responsiveness.

Abstract: A speedometer/tachometer assembly for an automotive vehicle, such as a heavy truck, has a ten section DIP switch for calibrating the speedometer and a like switch for calibrating the tachometer. When set to all "0's", each switch causes the corresponding meter to be driven by a variable frequency signal from a corresponding sensor, as calibrated by a corresponding calibration factor that has been preloaded in the non-volatile memory of a microprocessor that operates the meters. When set to all "1's", each switch causes the corresponding meter to be operated from pre-calibrated data appearing on a data link. When set to any other setting, the setting determines the calibration factor that is applied to the uncalibrated signal, and this is used to drive the corresponding meter.

Abstract: A circuit for processing a high frequency output signal from a variable reluctance transducer, this signal including an unwanted low frequency component, comprises a comparator having a first input receiving the transducer signal and a second input receiving the same transducer signal but via a low pass filter. The comparator therefore provides an output representing the high frequency variations in the transducer signal and substantially unaffected by the low frequency component. Alternatively, the transducer signal may be applied to a circuit providing a first output signal varying as the low frequency component and also providing a second output signal varying as the high frequency variations in the received transducer signal, the first output signal being used as a feedback control which tends to render the second output signal free of low frequency variations.

Abstract: A velocity signal is obtained by calculating both the selected signal of the differentiated signal of the position signal from a position detector and the selected signal of the sinusoidal wave signal according to position displacement, so that a velocity detection produces a smaller velocity detection error at a low velocity and generates no ripple component even when a high velocity is detected.

Abstract: A distance pulse unit measures the period between valid edges of asymmetrically shaped pulses from a distance pulse sensor. The unit counts individual clock pulse or averages eight individual clock pulses used to determine the period. The averaging occurs if the frequency of the sensor pulses are above a chosen frequency. The averaging aids in reducing the effects of the asymmetry of the sensor pulses.

Abstract: A wheel bearing apparatus provided with a wheel rotational speed detector which has a simplified L-shape and is constituted by a detector end portion and a circuit housing perpendicular to the detector end portion. The detector end portion contains a sensor in opposition to a detected member fixed to a rotating inside member of the wheel bearing and is embedded in an outside member of the wheel bearing, while the circuit housing contains a circuit for processing a signal input from the sensor and is mounted on an outside surface of the outside member in parallel with the axial direction of the outside member so that the circuit housing is inside in the radial direction of the outside surface of a flange provided for the inside member.

Abstract: A digital speedometer includes a pulse counter, a timing pulse generator, an indicator register, a display, and a comparator for comparing the magnitude relationship between a counted value counted by the pulse counter and the memorized value of the indicator register, two counters in addition to the pulse counter, and a plurality of logic circuits. The comparator generates signals indicative of the magnitude relationship between the counted value and the memorized value. The two counters may output a first or second gate signal respectively to the AND gate connected to the indicator register, in response to the signals output from the comparator at a predetermined time cycle depending upon the gate time controlled by the timing pulse generator, in such a manner so as to renew the memorized value with the counted value only when the number of occurrences of the output of the first or second signals reaches a preset number thereof.

Abstract: Disclosed herein is a circuit for measuring off-sets of a rotary shaft. In the circuit, a difference in time is produced, by a given sampling time, between an off-set output signal to be inputted to a low-level output selector and another off-set output signal to be inputted thereto. Owing to the above time difference, even though each off-set output signal undergoes a stepwise variation due to each DC off-set, the variation occur in each off-set output signal at the time difference. It is therefore possible to select either one of the off-set output signals, namely, the low-level off-set output signal, whereby the off-set output signal can be produced as an output free of a voltage level indicative of a rise in the off-sets due to an external disturbance corresponding to the variation.

Abstract: A method and apparatus are described, for measuring the angular velocity of a measuring body. In accordance with the present invention, the distance of the measuring body from a sensor varies periodically as the body is rotated, whereby the sensor emits a distance signal dependent on the distance, which distance signal is converted to a frequency-dependent signal in a converter circuit to determine angular velocity in a higher rpm region. To determine the angular velocity (or rpm) in a lower rpm region, the derivative of continuously varying distance between the sensor and a surface or partial surface of the measuring body is employed. In this way it is possible to measure rpm over a wide range down practically to zero.

Abstract: A method for identifying a measured value of a velocity or speed of an object where a measured value call-in can occur at any time. A chronological spacing of measuring pulses of a speed sensor is measured and a measured value is formed therefrom. The measurement is carried out until either a measured value call-in occurs, a maximum number of measuring pulses is registered, or a maximum measuring duration is exceeded. When no measuring pulse or only one measuring pulse is registered, a distinction is made in the formation of the measured value as to whether a measuring duration corresponding to a minimum velocity or minimum speed is upwardly or downwardly crossed. An initial counter reading is stored at every measuring start and at every first registered measured pulse. A final counter reading is stored at every further registered measuring pulse until either a measured value call-in occurs or the maximum measuring duration is exceeded.

Abstract: A tachometer device having a sensor generating an electrical signal at a frequency which is proportional to a speed to be detected, an operating drive member, and electrical link means connecting the sensor to the operating drive member. A device for limiting frequency variations in the pulses applied to the operating drive member is interposed between the sensor and said operating drive member.

Abstract: A process for maximizing the instruction processing efficiency of a digital computer for the purpose of calculating rotational speed wherein the calculation of speed is based upon speed signals generated by a tachometer. By (1) counting the quantity of the speed signals received during a fixed sampling period, and (2) recording the occurrence time of these speed signals only as necessary for the calculation of rotational speed, the invention improves over known methods in that it does not record the occurrence time of all speed signals, but rather records the occurrence time of only those speed signals necessary for the calculation. The invention accomplishes this by (a) anticipating when the speed signals necessary for the speed calculation will be generated (and subsequently received by the digital computer) and (b) recording the occurrence times only when it is anticipated that these necessary edges will be received by the digital computer.

Abstract: A system (apparatus and method) for measuring a revolution speed of a rotary member improves accuracy by estimating the speed during a unit operation period in response to pulse signals detected from the rotary member. When a pulse signal is not detected, the system obtains the revolution speed by selecting the lesser of a first estimated value and a second estimated value. The first estimated value is determined on the basis of the calculated revolution speed during the previous unit operation period and also the calculated acceleration during that previous operation period. The second estimated value is determined on the basis of a lapse time between a detected time of the last signal and the completion time of the current unit operation period.

Abstract: In an apparatus for detecting the abnormality of a rotational speed sensor adapted for, for example, an anti-skid control system, a time period within which a subsequent pulse will be generated by the rotational speed sensor in response to the rotation of a body of revolution such as wheel is estimated on the basis of the latest pulse interval of the pulses previously generated therefrom and a value corresponding to the force of inertia of the wheel developed on the braking operation thereof. The determination of abnormality of the rotational speed sensor is made when the subsequent pulse is not produced within the estimated time period. This is arranged based on the fact that the pulse interval depends upon the inertial force of the wheel. With the above arrangement, the abnormality detection of the speed sensor can be quickly made, so that a fail-safe control in a braking system can be speedily performed in response to the occurrence of abnormality of the speed sensor.

Abstract: A speed detector, for use with a tone wheel having metal teeth, employs two coils positioned in offset relation near the tone wheel for interacting with the tone wheel teeth and thus changing their respective inductances. The coils preferably include iron cores to enhance magnetic coupling. One coil is in a phase sense oscillator circuit and the other is an a tuned sensor network. The oscillator is coupled to, and drives, the tuned network. The change in coil inductances effects a phase shift of the resulting signals in the oscillator and the tuned network, the magnitude of that phase shift typically being double that for a comparable single coil system. The output signals of the oscillator and tuned network provide inputs to a phase condition detector which looks for a reversal in their phase sequence and uses such event to provide timing reference pulses for a final determination of speed in a known manner.

Abstract: A tachometer for measuring speed and armature position of a motor is disced whereby the counter electromotive force present in spikes on the power terminals are shaped, analyzed and displayed as tachometer information. The spikes occur as commutation takes place allowing a coarse angular armature shaft position to also be derived.