Abstract: A malfunction detection device for a wheel speed sensor includes a comparison circuit for comparing a wheel speed signal output from a wheel speed sensor with a predetermined voltage. A calculation circuit is provided for selectively increasing or decreasing a counter according to an output signal of the comparison circuit. A malfunction signal output circuit outputs a malfunction signal when the counter of the calculation circuit reaches a predetermined value.

Abstract: A method and device for calculating vehicle wheel speed which counts either one of the rise or the fall of each one of the pulse signals of the wheel sensor when the wheel speed is higher than a certain amount and counts both the rise and the fall of the pulse signals when the wheel speed is lower than the certain amount. This invention reduces the calculation time for the vehicle wheel speed.

Abstract: In a headlight integral with a speedometer the rigidity of the headlight case is ensured while making the headlight water and dust-proof. A meter hole is formed in the upper surface of a headlight case which constitutes a headlight, a speedometer is inserted into the meter hole from above and is secured to the headlight case through a meter stay in the interior of the headlight case. In addition, a meter cord and bulb cord are put together and extend between the exterior and the interior through a wiring hole formed in the rear portion of the headlight case.

Abstract: The analysis or evaluation circuit for analyzing an alternating voltage or current signal that includes a D.C. voltage or D.C. current component includes a window comparator having a circuit portion for comparing the alternating voltage or current signal to an upper threshold and a lower threshold and another circuit portion for adjusting the upper and lower threshold when one of the upper and the lower thresholds is reached by the alternating voltage or current signal. By means of a VCL output signal that switches when a threshold adjustment occurs, a frequency dependent signal may be produced that can be analyzed to obtain a rotational speed of a rotational body from which the input alternating voltage or current is derived.

Abstract: A rotational speed-detecting device of the present invention drives a sensor means 11, which includes a detecting unit that connects magneto-electric elements in series. A comparison voltage generator connects comparison voltage resistors in series, and is connected in parallel with the detecting unit, with a constant voltage by a constant-voltage control means 13, to which constant voltage is supplied by a constant-voltage generating means 14. The constant voltage means 14 controls a constant current of the constant-current means 15 with an on-and-off output from a comparison means 12 so as to superpose and flow a rectangular wave current in a power supply line between Vcc and VR.

Abstract: A variable reluctance sensor interface module having a variable attenuation circuit and a rectifier and differential single-ended conversion circuit for operating in a current mode to attenuate a differential input voltage. The variable attenuation circuit receives an input differential voltage from a magnetic sensor and converts the differential voltage to current. First and second current sourcing circuits, each including a plurality of current sourcing branches, receives the current and provides current attenuation by switching in and out transistor-based current sourcing branches. The rectifier and differential to single-ended conversion circuit converts the variably attenuated currents to a voltage output.

Abstract: The invention relates to a sensor arranged in a casing which is partly filled with a fluid (2) and which comprises a rotatable shaft (3) situated in the casing (1), where the sensor comprises a revolution counter sensor (6) for measuring the speed of revolution of the shaft (3) and on the other hand a temperature sensor (7) for measuring the temperature of the fluid (2). The revolution counter sensor (6) and the temperature sensor (7) form a unit which is situated in the casing (1) and above the surface of the fluid (2).

Abstract: A magnetic-field-to-voltage transducer includes a Hall element and a digitally gain-controlled Hall-voltage amplifier that produces an analog signal voltage Vsig having excursions of one polarity corresponding to the passing of magnetic articles. The gain of an AGC Vsig amplifier is only decreased in small sequential gain increments during an initial interval defined as that in which two excursions in Vsig have occurred, and the gain remains unchanged thereafter. Vsig is applied to the input of a peak-referenced-threshold signal detector that generates a binary output voltage, Vout, having transitions of one direction and the other direction corresponding respectively to the approach and retreat of the passing articles. The peak-referenced-threshold signal detector includes a dual-threshold-voltage comparator which is set to a large threshold at start-up.

Abstract: A device for detecting electromagnetic stray effects in systems with at least two inductive sensors which provide an essentially periodic output signal, performs a signal evaluation for evaluating signals of the sensors, a test for detecting an electromagnetic stray effect, whether periods of the signals to be evaluated lie within a period length of expected stray effects, a test, if applicable, whether detected signal progressions have at least a progression typical for stray pick-up, plausibility tests by means of at least one further detected signal in which a signal to be checked is compared with parallel measured other signals, and detecting a stray effect only if all tested conditions provide a result which is typical for stray effects.

Abstract: A circuit for generating a speed value corresponding to a rotational frequency of a rotating shaft. A digital tachometer circuit has a tachometer circuit and a copy/hold circuit. The tachometer circuit maintains an intermediate speed value which is incremented by a gain constant as the rotational frequency increases and is decremented as the rotational frequency decreases. The copy/hold circuit samples the intermediate speed value at selected intervals, thus generating the speed value. The speed value is displayed to a user and represents the vehicle's speed.

Abstract: A current magnitude sensing circuit for detecting a malfunction of a DC brushless fan. The current magnitude sensing circuit detects drops in the current magnitude in windings of a fan motor. Depending on the frequency of the current drops in the fan current, the current magnitude sensing circuit outputs either a high or a low voltage signal. The current magnitude sensing circuit operates by charging a capacitor beyond a certain voltage and thereby providing a high fan fail output signal when a fan is spinning too slowly for proper cooling of a device. Another capacitor is charged at a different time constant for setting the fan fail output of the current magnitude circuit low for indicating that the fan is spinning sufficiently fast.

Abstract: The present invention concerns the domain of inductive contactless sensors, allowing the position and/or the movement of a target sensitive to a magnetic field to be detected. The invention provides a miniature sensor comprising at least a primary coil generating an alternating magnetic field and at least two secondary coils for picked up such field, the coils being planar. The amplitude of the signal picked up by each coil is when the target passes in front of the coils, so that by measuring the signal amplitude or phase modulation, the speed and the direction of movement, or position of the object to be detected, is detected.

Abstract: A variable reluctance sensor interface module having a variable attenuation circuit and a rectifier and differential to single-ended conversion circuit for operating in a current mode to attenuate a differential input voltage. The variable attenuation circuit receives an input differential voltage from a magnetic sensor and converts the differential voltage to current. First and second current sourcing circuits, each including a plurality of current sourcing branches, receive the current and provides variable current attenuation by switching in and out transistor-based current sourcing branches. The rectifier and differential to single-ended conversion circuit converts the variably attenuated currents to a voltage output.

Abstract: A method for the exact determination of the speed of a rotating part, in particular the speed of the wheel of a motor vehicle, in which discontinuities present on the circumference of the rotating part are scanned without contact, an electric pulse being produced upon the detection of each discontinuity and the number of pulses thus produced being counted. In order definitely to be able to determine the dynamism of a rotating part without manufacturing tolerances of the incremental disks influencing this, the period of time within which all pulses of the rotating part are counted precisely once is determined, and the speed of the rotating part is determined therefrom.

Abstract: An after-change supply prevention unit prevents a cross coil from being supplied with a driving pulse signal with a duty ratio corresponding to a deflection angle calculated based on a period of a running pulse in a duration in which a period range judging unit judges that the period of the running pulse generated with the running of a vehicle is not in a predetermined range after the input state of the running pulse is shifted from the input state at the stoppage of the vehicle to the input state in running of the vehicle. While the supply of the driving pulse signal is prevented, a driving pulse signal with a duty ratio corresponding to a deflection angle calculated based on the period of the running pulse at the stoppage of the vehicle is supplied to the cross coil.

Abstract: A device for detecting motion of a movable part of an injection-molding machine uses an encoder coupled to the part which outputs two square waves which are a quarter-cycle out of phase. The two waves are used to generate trigger pulses at four times either encoder waves' frequency. The direction of the phase shift, positive or negative, depends on the forward or backward direction of motion of the part, and the trigger pulses are generated in on one of two logic circuits depending on the direction of motion of the part. The quadrupling of the encoder wave frequency increases the accuracy of motion measurement. The device uses AND/OR logic to generate the two sets of trigger pulses. The trigger pulses are counted to determine the distance the part has moved. The trigger pulses are also latched, and higher-frequency clock pulses are counted during the latched period to calculate the part's speed.

Abstract: A rotational speed sensor system which uses the sensor and a sensor electronic circuit to test the air slot between the speed sensor and an encoder to determine if the air slot falls within acceptable limits.

Abstract: A stepping motor type instrument 6 has driving circuits 3, 4 for driving a stepping motor based on a digital signal corresponding to a measurement quantity and a needle 9 fixed to a driving shaft end of this stepping motor indicates the measurement quantity by pointing out a graduation 8 on a character panel 7 corresponding to the measurement quantity.

Abstract: A precision oscillator includes a capacitor, a charging current source, a discharging current source, a switch for alternatingly connecting the capacitor to the charging current source and the discharging current source, and a hysteretic comparator connected to the capacitor for producing an oscillating signal responsive to charging and discharging the capacitor. The oscillator may also preferably include a duty cycle controller connected to at least one of the charging current source and the discharging current source for setting the charging current and/or the discharging current to thereby set a duty cycle of the oscillating signal by setting a ratio of the charging and discharging currents. The charging current source may have a current setting input for permitting setting of a charging current to the capacitor, and the discharging current source may have a current setting input for permitting setting of a discharging current from the capacitor.

Abstract: A high performance tachometer with memory device electronically connected to an input signal. A triggering device autometrically indicates the start of a drag racing event and activates the memory device. The memory device records only the racing event.

Abstract: A method for correcting the output sensitivity an angular velocity detector, in which, a first running directional data of the mobile object is successively calculated in accordance with the output signal of the angular velocity detector, a second running directional data of the mobile object is successively calculated in accordance with the positioning data obtained from a plurality satellites, the sensitivity correction coefficient is calculated in based on the stored first and second running directional data, and the sensitivity correction coefficient is multiplexed by the output signal of the angular velocity detector, so as to correct the output sensitivity of the angular velocity detector. Therefore, the dispersion of the output sensitivity of the angular velocity detector is eliminated to improve the accuracy of output sensitivity.

Abstract: A magnetic detecting apparatus is capable of performing accurate waveform processing without being affected by noise signals or the like, the level shifting circuit thereof having a fixed voltage shift so as to be free of varying amplitudes of analog signals. Waveform shaping circuitry for turning an analog signal detected from a giant magnetoresistive element into a pulse signal includes: the level shifting circuit for generating an amplified voltage (V1) of analog signals and a voltage (V2) which is higher than the voltage (V1) and a voltage (V3) which is lower than the voltage (V1); a circuit which alternately retains the minimum value of the voltage (V2) and the maximum value of the voltage (V3) as a reference voltage; and a comparator circuit which compares a voltage resulting from adding a hysteresis to the voltage (V1) with the reference voltage and issues a pulse signal.

Abstract: A tachometer interface circuit is provided for use with a multi-functional measuring device. The tachometer interface circuit includes a conditioning circuit which receives a series of ignition pulses from an internal combustion engine. The conditioning circuit converts the series of ignition pulses into a series of output pulses each having a constant pulse width. The tachometer interface circuit further includes a magnitude sensing circuit and an offset circuit. The magnitude sensing circuit senses the magnitude of the ignition pulses and activates the offset circuit when the magnitude exceeds a predetermined limit. Upon activation, the offset circuit inserts a resistor into the conditioning circuit to reduce the magnitude of the ignition pulses entering the conditioning circuit. In this manner, the tachometer interface circuit of the present invention is able to operate with ignition pulses having a variety of magnitudes.

Abstract: A multi-channel wheel speed sensor having a custom integrated interface circuit. The interface circuit is configured with voltage programmable threshold adjustment allowing the circuit sensitivity to be specially tuned to detect wheel speeds in very specific ranges for a variety of applications. This feature can be implemented in ABS and/or traction control systems wherein in ABS mode a lower sensitivity adjustment can be used since wheel speeds below 5 mph do not need to sensed and processed precisely and in traction control mode very low wheel speeds, 1-1.5 mph are sensed and processed especially at non-drive wheels which provide speed reference for slipping or spinning drive wheels. The interface circuit is also configured with a test circuit for testing the integrity of the speed sensors and for providing information to the controller about the sensor/tone wheel gap.

Abstract: A device for measuring a rotary frequency of a rotating vehicle tire includes a number of first poles uniformly arranged on a circle with a radius R1 on or within a vehicle tire. A first sensor, for sensing the first poles, is stationarily arranged at a distance R2 from a rotational axis of the vehicle wheel. The radii have the following relationship: 0.9 R1<R2<1.1 R1. A computing unit is connected to the first sensor. The first sensor sends first signals to the computing unit when the first poles pass the first sensor. The computing unit determines a first time period between passing of sequential ones of the first poles. The computing unit multiplies a reciprocal value of the first time period by a reciprocal value of the number of the first poles to a multiplication product and supplies the multiplication product as a measure of a first rotary frequency to a user device.

Abstract: A method for detection of passing magnetic articles which includes an initial step of sensing an ambient magnetic field and generating a voltage, Vsig, proportional to the magnetic field. A threshold voltage is generated as a percentage of the peak-to-peak voltage of Vsig. The method further includes the step of generating a proximity detector output voltage that becomes one binary level when Vsig rises to exceed the threshold voltage and another binary level when Vsig falls to below the threshold voltage. The threshold voltage is periodically updated to remain the percentage, within a predetermined tolerance, of the peak-to-peak voltage of Vsig in response to changes that may occur in the peak voltages of Vsig.

Abstract: A high performance tachometer for use in high performance racing vehicles, such as dragsters, is disclosed. The tachometer has an input signal indicative of the vehicular engine speed and an output display for displaying the instantaneous engine speed as indicated by the input signal. The tachometer includes input controls for directing the control and operation of the tachometer.

Abstract: A rotary pulse generator kit for monitoring the rotation of a shaft includes an enclosure capable of accepting two different sensor modules. Each sensor module may include axially aligned magneto-resistive sensing elements that sense magnetic poles imprinted in a pattern on a rotor that rotates with the shaft. Two sensor modules having different incremental pulse output rates may be supplied with the tachometer kit. In this way, the shaft may be monitored by a pair of sensor modules pre-set at different incremental pulse output rates, mounted to the same enclosure.

Abstract: An apparatus and method for testing, for example, ABS systems in which a variable reluctance detector is positioned adjacent a ring of ferromagnetic teeth mounted on a wheel is provided. The amplitude and period of individual cycles of the output of the detector are measured and the product of the measured amplitude and period is calculated to provide an indication of the performance of the ABS detector system. The rate of change of the product may be analyzed to more reliably distinguish fault conditions from the effects resulting from, for example, variations in the speed of the wheel. The peak-to-peak amplitude of the product may be monitored to indicate tooth eccentricity, and the mean of the product may be monitored to indicate the detector-to-tooth gap.

Abstract: A revolution-speed/temperature hybrid sensor includes a hybrid sensor unit which has a five-input-three-output convertor and outputs a revolution-speed/temperature hybrid signal, and a revolution-speed/temperature detector for separating the revolution-speed/temperature hybrid signal. The five-input-three-output convertor has an adder for adding the revolution speed signal of pulse waveform and temperature signal of analog form so as to generate a revolution-speed/temperature hybrid signal. By virtue of the five-input-three-output convertor, the revolution-speed/temperature hybrid sensor requires a smaller number of harnesses and is downsized compared to a conventional arrangement.

Abstract: A method is disclosed for measuring the linear velocity of recording of data recorded a CD using a Hall sensor. A Hall sensor is placed in the spindle motor of a CD drive to produce a signal based on alternating magnetic flux in the spindle motor. An amplified and processed version of the signal output from the Hall sensor during operation of the CD drive is monitored to measure the timing of three successive inversions of the signal. Based on this timing measurement, the rotational speed of the spindle motor is determined. The recording linear velocity of the data recorded on the CD presently mounted in the CD drive is obtained based on the rotational speed determined from the Hall signal and on a reference rotational speed. As a result of using this method for obtaining the recording linear velocity of the data recorded on the CD, no errors are generated based on the number of tracks the pickup is moved across, and the time necessary for measuring the recording linear velocity is reduced.

Abstract: An input filter for a vehicle anti-lock brake system control module has a filter section for attenuating input signals having mid-range frequencies.

Abstract: An automobile deceleration indicating device includes a signal generation unit which is coupled to the engine system for generating a signal of which the frequency is in general proportional to the operation speed of the engine, an amplifying circuit for amplifying the signal from the signal generation unit, a shaping circuit for generating a series of pulses from the amplified signal so that the frequency of the pulses representing the operation speed of the engine, and a micro-processor based circuit which receives the pulses and applies a control signal to the stoplight via power amplification circuit when the frequency of the pulses is decreased which indicates that the engine is slowed down.

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: A noncontacting power transfer apparatus, a noncontacting signal transfer apparatus, to be referred to below as a power coupler and a signal coupler, respectively, and a separate machine apparatus that uses these couplers are disclosed. The power coupler is composed of a primary side and a secondary side that are fixed to a static unit and rotatable unit of the machine apparatus, respectively, such that its output does not vary with arbitrary rotation by the rotatable unit. The signal coupler is composed of receiving side portion having a electric-to-light conversion device that converts an electric signal to an optical signal of rotational symmetry relative to the axis of rotation of the rotatable unit and a photoelectric conversion device that converts an optical signal to an electric signal. Accordingly, the rotatable unit can be supplied with power from the static unit even while rotating, and moreover, can communicate with the static unit.

Abstract: An adaptive digital filter for filtering noise from a binary signal having a baseline that is low and including valid pulses that are high, a system for monitoring a rotating element employing such an adaptive digital filter, and a method for filtering. The adaptive filter discriminates noise pulses from valid pulses by eliminating pulses of shorter duration than a specified high time threshold and eliminating pulse occurring prior to the expiration of a specified low time threshold from the filtered signal generated by the filter from the binary signal. The filter also includes a mechanism for analyzing the filtered signal and dynamically and automatically adjusting the specified high time threshold and specified low time threshold based on timing changes in the filtered signal. A method of filtering is also presented whereby the specified high time and low time thresholds are adjusted dynamically in accordance with the timing data calculated by the filter.

Abstract: A physical amount detecting apparatus, preferably, an acceleration sensor, includes a sensor element, an A/D converter, a control unit and an activation unit. The sensor element is activated by a supply voltage and outputs an electric signal in accordance with a predetermined physical amount. The A/D converter digitizes an analog electric signal and outputs digital data. The control unit calculates a control amount in order to control the sensor element, as the electric signal is set to a predetermined output, based on the digital data, and generates a control signal in accordance with the control amount. The activation unit activates the sensor element in accordance with the control signal. As a result, the control unit outputs a detecting signal indicating a physical amount in accordance with the control amount or the control signal.

Abstract: Novel rotation sensors are disclosed, sensors with a temporal resolution of one measurement per rotation. A transparent or absorbing substrate can be coated with a transparent thin film to produce a linear response in reflectance versus angle of incidence over a certain range of angles. The best results were obtained when the incident light was s-polarized. For example, a Si substrate coated with an SiO.sub.2 film was used in constructing a reflection rotation sensor. Experimental results and an error analysis of this rotation sensor are presented.

Abstract: A sensor system includes a single sensor means, two sensed signal processing circuits for processing the output signal of the sensor means, both the signal processing circuits being substantially equal in circuit construction, and an abnormality detecting circuit for detecting an abnormality on the basis of the difference between the output signals of the two sensed signal processing circuits.

Abstract: A circuit for use with a magnetic sensing device having at least first and second sensors has a summing amplifier for providing a difference signal and a peak detector for detecting peaks in the difference signal. The peaks determine a spatial offset of a transition in a sensed body.

Abstract: A detector 1, with its object of detection having operation characteristics that include a shift from a first state to a second state, outputs a signal e1 that corresponds to the operation characteristics of the object of detection. A first state detection circuit 2 generates a first output signal SA corresponding to the first state based upon the signal e1 provided by the detector 1. A second state detection circuit 3 generates a second output signal SB corresponding to the second state based upon the signal provided by the detector 1. The second output signal SB is generated only when the object of detection shifts from the first state to the second state in a normal manner while the first output signal SA is being generated. A state judgement circuit 4 generates a state judgement output signal Z on condition that there has been a period of time during which the first output signal SA and the second output signal SB have been both at high.

Abstract: An engine revolution counter comprising a mount 2 having first electric source terminals 20 for supply of electric power from outside and first measuring mode setting terminals 21 through 23, and a measuring part main body 1 provided on said mount in freely attachable and detachable way and having measuring mode setting switches and a display panel 11 on the front face thereof to display measured results and also having a measuring function of the number of revolution of the engine, wherein the first electric source terminals 20 and the first measuring mode setting terminals 21 through 23 are connected to each of second electric source terminals 16 and second measuring mode setting terminals 17 through 19 provided in said measuring part main body 1.

Abstract: A sensor for determining the rotational speed of a rotating element. The sensor includes a giant magnetoresistive ratio sensing device which is magnetically coupled to the rotating element and includes an output terminal. The sensing device generates an output signal at the output terminal having a frequency corresponding to the rotational speed of the rotating element. A wave-shaping circuit is connected to the output terminal for receiving the output signal and for generating a digital switching signal having a frequency equal to the frequency of the output signal. A frequency divider has an input connected to the wave shaping circuit for receiving the digital switching signal. The frequency divider generates, in response to the digital switching signal, a square wave output having a 50% duty cycle and a frequency equal to the frequency of the digital switching signal divided by a predetermined divisor.

Abstract: An electronic circuit having control data registers (24-28) for receiving the output of a digital counter (20) that records clock pulses within a measured time that is determined by a rotary speed sensor (14) which produces a square wave pulse train signal and separate registers (30,32) for recording the time of each signal developed by the speed sensor and the time to produce a pulse train signal of predetermined length whereby the data in the data registers may be used to determine velocity and derivatives of that velocity for use in solving dynamic equations stored in memory thus effecting control system output functions.

Abstract: In accordance with the teachings of the present invention, a wheel speed sensor signal conditioning circuit is provided for conditioning sensor output signals received from a variable reluctance wheel speed sensor. The conditioning circuit includes filtering circuitry and peak detecting circuitry that detects the positive and negative voltage peaks of a sensor output signal irrespective of the sensor output signal crossing a reference voltage level. When the sensor output signal exceeds a predetermined peak to peak voltage level, the peak detecting circuitry limits the amplitude of the output signal and forms a dynamic high pass filter. A comparator circuit is coupled to the peak detecting circuitry and outputs a first signal when the peak detecting circuitry detects a positive voltage peak and outputs a second signal when the peak detecting circuitry detects a negative voltage peak of the sensor output signal.

Abstract: An in-line roller skate includes a transducer portion capable of sensing the rotary movement of at least one wheel on the roller skate and transmitting information concerning the same to a receiver worn on a user's wrist. In the preferred embodiment, the transducer portion includes a magnet attached to one of the plurality of wheels and a sensor positioned in a shoe portion to detect the magnet and produce electrical pulses containing information corresponding to the angular velocity of the wheel. The transducer portion also includes a micro-controller, a transmitter and an antenna. The micro-controller creates a digital data stream containing information corresponding to the angular velocity of the wheel, which is then modulated onto a carrier wave produced by the transmitter. The transmitter transmits the coded signals to the receiver. The receiver demodulates the carrier wave, reproducing the digital data stream.

Abstract: The device proposed comprises a Hall sensor (101) with an associated magnet (102), a pulse-generation wheel (104) rotating at an angular speed w and fitted with teeth having a rising and falling face, the wheel turning in front of the sensor to generate a curve which corresponds exactly to the tooth-face positions and which can be used to determine precisely the position of the rotating shaft. The Hall sensor 9101) registers the variation with time of the magnetic flux density through the pulse-generation wheel (104) as a Hall voltage signal. This signal is converted by a differentiator circuit (103.2) into a differentiated signal. The maxima and minima of the differentiated signal are determined and a digital output signal (AS) is generated form the differentiated signal, the low-level to high-level transitions in the output signal corresponding to the maxima of the differentiated signal and the high-level to low-level transitions corresponding to the minima.

Abstract: A microprocessor-controlled speedometer/odometer including a single-chip microprocessor which is previously recorded with operation programs according to different requirements. The programs of the microprocessor are changeable in accordance with the requirements of different speedometers.

Abstract: A regulation of the sensitivity with a circuit in which the output signals of an inductive transmitter must be evaluated is performed so that the sensitivity in the event of small transmitter output signal is reduced until no trigger signal is obtained. Then the sensitivity is again increased by one step, and the thusly obtained sensitivity the further evaluations are performed. The method can be used for example in rotary speed sensors which are utilized with the transmission control in motor vehicles.

Abstract: A drive speed detector for a pickup feed motor including a detector for detecting the drive speed of the optical pickup feed motor by generating an AC signal with a frequency which is proportional to the drive speed of the optical pickup feed motor and a controller for controlling the sensitivity of the detecting means in order to uniform an amplitude level of the AC signal output from the detecting means.