Abstract: A power drive control device of an automatic door, including a gear box having a shell; and a motor drive, the motor drive having a front cover integrally made with the shell of the gear box together, and a back cover covered on the front cover to hold a motor shaft, a stator coil around the motor shaft, a light chopper, and a photoelectric pick-up device, the front cover having a receiving chamber, two recessed holes and one screw hole formed in the receiving chamber and adapted for securing the photoelectric pick-up device in place, the light chopper being mounted around a bearing around the motor shaft to act with the photoelectric pick-up device, enabling the photoelectric pick-up device to monitor the operation of the motor shaft.

Abstract: In one embodiment of the present invention, a "one-touch-up" power window system is provided for a motor vehicle. The system includes a controller which controls the power window motor. One function of the controller is to determine whether an obstruction impedes travel of the power window. The controller takes a plurality of samples of the electrical current drawn by the power window motor. If the last sample varies by more than a predetermined amount from any of the past samples taken over a predetermined distance of travel of the window, the controller concludes that an obstruction impedes the travel of the window. The controller then stops or reverses the power window motor to stop or reverse travel of the power window. In this embodiment of the present invention, distance of travel of the window can be inferred from rotations of the power window motor.

Abstract: A power closure system for a motor vehicle includes a closure, a closure frame, an electric motor, a first displacement sensor and a microprocessor. The electric motor has an output shaft. The closure frame defines a seated position of the closure. The displacement sensors both indicate rotation of the drive motor output shaft, with the second sensor being offset from the first sensor. The microprocessor includes means for measuring a first time for the output shaft of the motor to rotate a predetermined amount using signals from the first sensor. The microprocessor also includes means for measuring a second time for the output shaft of the motor to rotate a predetermined amount using signals from the first sensor. As well, the microprocessor includes means for establishing a reference, or limiting, time signal for the second time signal using the first time signal. The microprocessor has means for comparing the second signal to the reference or limit signal.

Abstract: A vehicle-mounted motor drive apparatus which stops the rotation of a motor immediately after an object obstructs a movable part driven by the motor. The drive apparatus includes a motor drive device for selectively driving and stopping a motor, an electric current measuring device for measuring a value of electric current flowing through the motor, a change-in-current-value detecting device for detecting an incremental change in the motor current, and a motor control device for supplying a first control signal or a second control signal to the motor drive device. The motor drive device continuously drives the motor according to the polarity of the detected increment of the current value in response to the first control signal, and immediately stops driving the motor in response to the second control signal.

Abstract: A motor vehicle having a plurality of pivotal doors and a sliding door each movable between a closed and an open position has a lock system with a respective lock on each of the doors having an electrical motor energizable to set the respective lock in a locked position and in an unlocked position. A sensor at the sliding door produces a closed-door output when the sliding door is closed and an open-door output when the sliding door is open. Contacts on the sliding door are connected to the respective motor and contacts on the vehicle are engageable with the sliding-door contacts only in the closed position of the sliding door. A command unit can generate a lock-doors output and an unlock-doors output and an electrical controller is connected to the sensor, to the command unit, to the pivotal-door motors, and to the motor-vehicle contacts for energizing the pivotal-door motors to place the pivotal-door locks in the locked position after generation of the lock-doors signal.

Abstract: A sensing system is provided which senses an obstruction between a closure member and a frame, regardless of the direction of the input force to the sensor, such that when the obstruction is sensed to be between the closure member and the frame, the operation of the closure member can be controlled to prevent further closing of the closure member upon the obstruction. The sensing system includes a membrane switch assembly which changes resistance when a force component caused by the obstruction is exerted on the switch assembly.

Abstract: An on-car motor driving apparatus is equipped with a motor for moving a moving unit such as a window of a motor car, a motor driving controller which controls the revolution, stop, and rotational direction of the motor, and a current measuring and comparing device which measures the variation in current per unit time of the motor and compares the measured variation in current with a preset value. The on-car motor driving apparatus stops the revolution of the motor and/or reverses the rotational direction of the motor through the motor driving controller. The apparatus is further equipped with a voltage measuring device for measuring motor driving voltage and a voltage-based time setting device which changes the length of the unit time in accordance with the driving voltage value measured by the voltage measuring device. Line voltage is supplied to a differential amplifier only when the line voltage is supplied to the motor.

Abstract: A maintenance station for an ink jet printer comprises two modules supported from the printer middle frame by a tongue and groove arrangement and secured in place only by retaining elements integrally formed with the middle frame. The first module includes a wiper element and a cap to provide an air seal around the nozzles. The wiper and cap are mounted on a pivoted rocker element so that as the wiper is moved toward the printhead the cap is moved away therefrom and visa-versa. The second module carries a small DC motor, a nut with a pair of forked arms, and gearing for converting bidirectional rotation of the motor into linear reciprocal motion of the forked arms. The forked arms engage projections on the rocker element so that the wiper or cap is moved toward or away from the printhead depending on the direction of rotation of the motor. In a first position of the rocker element the wiper is positioned in the path of the printhead so as to wipe the nozzles as the printhead is moved back and forth.

Abstract: An electric motor (20) is controlled to move a vehicle window (28) between an upper limit position and a lower limit position. The rate of change of current flow to the motor is determined during upward movement of the vehicle window toward the upper limit position. A threshold rate of change of current flow value to the motor is stored which is a function of a plurality of determinations made of the rate of change of current flow to the motor during upward movements of the vehicle window toward the upper limit position. The stored threshold rate of change of current flow value is modified on each movement of the vehicle window to the upper limit position to make the stored threshold rate of change of current flow value a function of the determinations made of the rate of change of current flow to the motor which are most current in time.

Abstract: A motor control system for controlling operation of an electric motor associated with a motor-operated vent in a vehicle. The system monitors and stores data relating to the operating current and detects occurrences of abnormal loads applied to the vent by determining whether the monitored operating current exceeds one of several predetermined thresholds. The predetermined thresholds are dynamically modified in accordance with monitored condition variations of the operating current. The dynamically modified thresholds are initially based on either a value associated with the stall current of the vent motor or the start spike current of the vent motor. In addition, an embodiment is provided for monitoring and storing data relating to ripple current waves associated with the operating current, so that occurrences of abnormal loads may be detected by determining whether the frequency of the monitored ripple current waves is less than a predetermined value.

Abstract: A drive control device for an opening and closing member is active to optimally adjust a threshold level for pinch detection. Utilizing a speed sensor or the like, the closing speed of the opening/closing member is detected. The value of the closing speed is renewed in accordance with the closing position and stored in memory. Based on memorized data, a predicting circuit derives a future closing speed. To the predicted value there is added an allowed addition value, to permit a threshold level setting circuit to set an appropriate threshold for pinch detection. The allowed addition value is adjusted in accordance with the closing speed of the opening/closing member by a threshold level adjusting circuit.

Abstract: A mini-blind actuator has a motor and a housing that holds the motor and a dc battery. The rotor of the motor is coupled to the baton of the mini-blind for rotating the baton and thereby opening or closing the slats of the mini-blind. Alternatively, the rotor is coupled to the tilt rod of the blind to rotate the tilt rod and thereby open or close the slats of the mini-blind. A control signal generator generates a control signal for completing the electrical circuit between the battery and the motor. The control signal can be generated in response to a predetermined amount of daylight or in response to a user-generated remote command signal.

Abstract: The control device controls an electrically powered foldable rearview mirror in which a mirror body is reversibly rotatable around a shaft by an electric motor contained in the mirror body and in which the mirror body rotation is stopped in a predetermined erected position and folded position by rotation stop devices. The control device for controlling mirror rotation includes a switching circuit for switching the power supply connections to the motor to rotate the mirror body in one of two direction, a relay circuit for supplying and cutting off power to the motor and a relay control circuit connected to the relay circuit and the motor.

Abstract: An apparatus for driving and controlling a motor which moves a movable portion of a vehicle by driving force of the motor. The apparatus includes a drive stopping circuit for comparing a value of current detected by a current detection circuit, which detects drive current of the motor when the movable portion is being moved, with a predetermined comparison current value, and for stopping driving of the motor at a time when a detected current value exceeds the comparison current value. The apparatus also includes a comparison current varying circuit for varying the comparison current value based on a temperature of an environment of the movable portion. Since it is possible to carry out temperature compensation based on ordinary drive current and lock current of the motor, the comparison current value can be set within a wide range.

Abstract: An adaptive control system and method for a vehicle window. The system and method include sensors for determining a motor current corresponding to a window position and for detecting a motor stall, and an electronic control module (ECM) for providing a position counter having a count representing the window position. The ECM is also provided for setting, independent of a dedicated motor actuation input signal, a second historical limit equal to the count when the window is driven by the motor toward the closed position and a motor stall is detected, as well as setting, independent of a motor actuation input signal, the second historical limit equal to the difference between the second historical limit and the count, and the count equal to a first historical limit, respectively, when the window is driven by the motor toward an open position and a motor stall is detected.

Abstract: A method for operating power window apparatus with a safety device which stops the closing operation of the window in response to the detection of an object-caught state, which prevents the incomplete close of the window, and can accurately detect the object-caught state. The opening/closing position of the window is detected by counting pulses generated as the window moves. A region where a safety control can be carried out is determined on the basis of the detected opening/closing position. When the window reaches a position near a position where the window is fully closed, the count indicative of the opening/closing position detector is reset. The resetting operation is carried out so that a time point where the relative speed of the window is reduced is set at the fully closed position of the window.

Abstract: A mini-blind actuator has a motor and a housing that holds the motor and a dc battery. The rotor of the motor is coupled to the baton of the mini-blind for rotating the baton and thereby opening or closing the slats of the mini-blind. A control signal generator generates a control signal for completing the electrical circuit between the battery and the motor. The control signal can be generated in response to a predetermined amount of daylight or in response to a user-generated remote command signal.

Abstract: A system for inverter control of a servo motor where in the inverter is connected to a velocity control section and a position detection section is connected to the servo motor. Primary and back-up power for operating the velocity control section and the position detection section is provided by power sources that are located in the velocity control section and are connected to the position detection section by cables. The cables used to provide signal transmission between the position detecting section and the velocity control section are switched by relays to transmit the power of a power failure back-up power supply at the time of a power failure. Also, a transmission signal transmitted from one of the position detecting section and the velocity control section to the other via a first cable connection is returned via a second cable connection and a connection fault may be judged depending on whether or not the return signal matches the transmission signal.

Abstract: A power window apparatus is controlled by comparing present rotational frequency of a motor with a reference value selected depending on a present position of a window glass among plural reference values predetermined at every position of the window glass, supplying an electric current to the motor in the closing direction of a window when the present rotational frequency of the motor is larger than selected reference value, supplying the electric current to the motor in the opening direction of the window when the present rotational frequency is not larger than the selected reference value and the window glass does not arrive in a full-closed position, and cutting the current supply to the motor when the present rotational frequency is not larger than the selected reference value and the window glass arrives in the full-closed position.

Abstract: A motor control system for controlling operation of an electric motor associated with a motor-operated vent in a vehicle. The system monitors and stores data relating to the operating current and detects occurrences of abnormal loads applied to the vent by determining whether the monitored operating current exceeds one of several predetermined thresholds. The predetermined thresholds are dynamically modified in accordance with monitored condition variations of the operating current. The dynamically modified thresholds are initially based on either a value associated with the stall current of the vent motor or the start spike current of the vent motor. In addition, an embodiment is provided for monitoring and storing data relating to ripple current waves associated with the operating current, so that occurrences of abnormal loads may be detected by determining whether the frequency of the monitored ripple current waves is less than a predetermined value.

Abstract: A mini-blind actuator has a motor and a housing that holds the motor and a dc battery. The rotor of the motor is coupled to the baton of the mini-blind for rotating the baton and thereby opening or closing the slats of the mini-blind. Alternatively, the rotor is coupled to the tilt rod of the blind to rotate the tilt rod and thereby open or close the slats of the mini-blind. A control signal generator generates a control signal for completing the electrical circuit between the battery and the motor. The control signal can be generated in response to a predetermined amount of daylight or in response to a user-generated remote command signal.

Abstract: A valve, particularly for shutting off a flow, includes a housing. A rotationally fixed threaded part is rotationally fixed and axially displaceable in the housing. A rotatable threaded part is axially resiliently and rotatably supported in the housing. A brake device has at least two friction surfaces facing one another. One of the friction surfaces is rotationally fixed in the housing, and the other of the friction surfaces is rotationally fixedly joined to the rotatable threaded part. The friction surfaces are pressed against one another by an axial displacement for braking a rotary motion of the rotatable threaded part and forming a braking surface, if a predetermined command force upon the rotationally fixed threaded part is exceeded. At least one of the friction surfaces has a predetermined free angle for rotational fixation.

Abstract: A controller for energizing a power window or panel such as a power sunroof. The disclosed controller senses both hard and soft obstructions and deactivates a motor that moves the sunroof when an obstruction is detected. The controller also senses obstructions during start-up of the motor and regulates the speed of the window or panel by pulse width modulating motor energization signals.

Abstract: The electrical control system for an electrically powered foldable rearview mirror having a mirror body mounted on a hollow supporting shaft extending from a supporting base so as to be movable between a folded state and an erected state, comprises a reversible motor and reduction gear drive contained in the mirror body; a motor drive circuit connected to the reversible motor to drive the mirror body between the folded state and the errected state; a mechanical stop device to stop rotation of the mirror body when the mirror body reaches the erected state or the folded state including convex and concave portions on the a root portion of the shaft and mirror body respectively; a noncontacting sensor for detecting a halt to motor rotation as a result of a halt of mirror body rotation; and a control circuit for interrruption of the motor drive circuit when the noncontacting sensor detects the halt of the motor rotation.

Abstract: A method and device for controlling a headrest, as well as a headrest drive mechanism, wherein the headrest is to be controlled so as to cause the same to automatically return to the use position if it disposed and stopped between an intermediate position and use position.

Abstract: A motor controller for reversibly driving a member to be driven along a predetermined path of travel is capable of sensing the speed of the member to be driven and to compare with a predetermined speed level and to adjust the motor drive until the rate of advancement of the driven member corresponds with the predetermined speed level. The motor drive means is completely deactivated if the actual speed should not reach a predetermined start-up threshold within a selected time interval after the motor is initially turned on or should drop beneath the stay-on threshold level which is set beneath the desired speed. The motor drive can also be regulated to run at different reduced or normal speed settings depending upon its intended application.

Abstract: An arrangement for detecting a motor overload condition by examining the phase angle relationship between the motor voltage and current. As the load increases, the phase angle difference approaches zero. By measuring the zero crossings of the voltage and current and providing a signal representative of the time difference between these crossings, the phase angle relationship is determined and, accordingly, so is the motor load. Specifically, a saturable ferromagnetic core is utilized to detect the current zero crossings.

Abstract: Method and device for controlling a side support in a powered seat, in which the side support device is controlled in its opening/closing motion in order that it is not moved repeatedly sensitive to each of acceleration being applied to the seat during driving on a curved road, by virtue of a standard checking process for determining an excessive acceleration, and then a short and long hold time system for holding the side support device in unmoved state against repeated or plural intermittent occurrences of accelerations being applied to the seat.

Abstract: A method and device for controlling a headrest provided on a seat back of a seat, in which there is arranged an over-load detecting system for detecting an over-load state of a motor and automatically stopping the motor if the over-load state is detected during displacement of the headrest to a use position, or automatically driving the motor to return the headrest to a use position if the over-load state is detected during displacement of the headrest to a non-use position. This allows for removing an object caught in between the headrest and seat back with much safe.

Abstract: An automatic window opening/closing system includes a motor for driving a window. In association with the window, a pressure responsive sensor (preferably, a pressure responsive sensor with a coaxial structure having uniform sensitivity to pressures in all directions) is provided. A detector circuit is coupled to the pressure responsive sensor and evaluates a rate of change of a pressure on the sensor, thereby detecting a squeezed object caught in a way of the window during an operation of the system. A motor control circuit is provided to control the motor in response to a squeezed object detection signal from the detector circuit in such a direction to release the object from the window. The motor control circuit detects an overload condition of the motor in accordance with a motor terminal voltage and deenergizes the motor to prevent the motor from generating heat. Therefore, this system achieves improved performance, high reliability and safety.

Abstract: In an apparatus for controlling a D.C. motor used in the lifting and lowering operation of a window blind or an awning, pulses induced as a result of rotation of the motor rotor are used for delivering signals to a signal receiving means. The signal receiving means includes a counter for counting the induced pulses, a memory that stores the number of pulses required for the blind or awning to move between its end positions, and a comparator circuit for generating a control signal when the operating current to the motor exceeds a predetermined value, and delivers signals to stop the motor at the end positions of the blind or awning.

Abstract: An electric drive comprises a base (1), an electric motor including a frame (2) and, mounted therein, a stator (3) and a rotor (4), a lead screw (5), an axial force limiter disposed between a bearing surface (12) of the base (1) and a pressure surface (13) of the frame (2) of the electric motor and comprising washers (9) and (10) with a resilient member (11) placed therebetween. The electric motor frame (2) is axially displaceable and kinematically coupled with the axial force limiter. The base (1) is provided with a stop (14) facing the pressure surface (13) of the frame (2), and the frame (2) is provided with a stop (15) facing the bearing surface (12) of the base (1).

Abstract: A universal load sensing gearbox integrating a safety mechanism for use, for instance, with motor driven closures, such as garage doors, barriers and gates, includes a housing which encases a worm slidably mounted on an input shaft and adapted for rotation therewith. The input shaft is connected with the motor driving the closure. The worm is engaged with a worm gear which is mounted on an output shaft which is connected with the closure. Dished washers are provided generally around the input shaft at both ends of the worm to urge the worm in a central meshed engagement with the worm gear. A motion transmission device is provided on the worm and is adapted to slide therewith to detect a longitudinal movement thereof and to transmit this movement to an actuating device which is adapted to stop and/or reverse the motor.

Abstract: A circuit for controlling bi-directional operation of a vehicle window lift motor having a toroidal coil sensing counter-emf perturbations in the motor current line. An EXPRESS mode switch, upon momentary actuation, latches an electronic switch to operate a relay to provide continuous motor rotation for lowering the window. Subsequent momentary switch actuation unlatches the electronic switch to cut interrupt window motor current. Window lift motor stall is detected by a toroidal coil which senses loss of motor line perturbations and unlatches the electronic switch to open circuit the motor relay.

Abstract: This invention relates to an attachable hand-operated/automatic dual usage venetian blind controller which can be attached to an existing venetian blind to set the blades of such a venetian blind together at any angle or to draw up the blades together to one side of the window by means of infrared remote control so as to regulate the light and air passing through. During power failure, the venetian blind can be controlled through hand operation without removing the controller. The controller of this invention is generally comprised of two DC motor and speed reducing gear set assemblies, two guide wheels, two pressure wheels, a beading cord driving wheel, a pull cord driving wheel, an infrared receiver control circuit, and an infrared transmitter.

Abstract: There is provided an automotive power seat assembly comprising a movable seat cushion, a backrest tiltable relative to the seat cushion, a reclining mechanism for reclining the backrest, seat rail means including upper rails secured to the seat cushion and lower rails secured to the body of the automobile, a motor for driving the reclining mechanism and a current control circuit for controlling the flow of current through the motor.

Abstract: A motorized window blind actuator including input means for receiving regulated voltage and first variable reference voltage signal. A motor having an output shaft which connects to the window blinds to open and close the window blinds is controlled by a controller/driver component. A transducer is operatively associated with the output shaft of the motor to assist in producing a second voltage reference signal which is related to the actual position of the motor output shaft, and in turn related to the actual position of the slats of the window blind. The first voltage reference signal is related to the desired setting and position of the window blind. First and second voltage reference signals are continually compared. If they are sufficiently different, the motor is directed by the controller/driver to adjust the window blinds until signals are sufficiently the same, or, until the output shaft of the motor hits physical limits which cause an over current situation resulting in stoppage of the motor.

Abstract: The present invention comprises a thrust actuated control for use in a motor operated valve having a motor operator including a motor drive, a stem nut coupled to the motor drive for rotation about an axis and a stem nut lock coupled to the motor drive for preventing axial movement of the stem nut. The valve includes a valve gate, a valve seat and a valve stem coupled to the valve gate, the valve stem threadingly engaging the stem nut for axial movement in a first direction upon rotation of the stem nut in a first direction to move the valve gate toward and into engagement with the valve seat and for axial movement in a second direction upon rotation of the stem nut in a second direction to move the valve gate out of engagement with and away from the valve seat.

Abstract: An overload protector for a robot arm has an open-topped cylinder into which a piston is inserted. The piston is held against a circumferential stop surface of the cylinder by compression springs.

Abstract: The present invention is a load sensor for use in an automatic portal operator such as an industrial gate operator. An induction motor is employed to move the gate. The power factor of the AC electric power supplied to the induction motor is monitored. A safety operation is triggered when the power factor indicates the motor load is greater than a predetermined amount, as when an obstruction is encountered by the gate.

Abstract: An overload detection mechanism for a robot is disclosed, wherein first and second members are relatively urged together by an urging means to urge the axis of the second member toward the Z axis of the first member. The second member is guided in any movements departing from coaxial alignment, and the first member is supported near the end of a robot arm. A tool mount or workpiece mount is connected to the second member. An electrical device is mounted on one of the members, and a device actuator on the other of the members, with the reaction means acting between the members to relatively move the members upon tilting from an X-Y plane normal to the Z axis, or axial thrust applied by the tool mount to the second member. In this manner, an overload of a tool in the tool mount establishes relative movement between the first and second members, so that the electrical device is actuated to change an electrical condition thereof and can be connected to stop movement of the robot.

Abstract: A valve for shutting off a flow having a housing wherein a plug member is movable between "on" and "off" terminal positions by means of a thread; a rotary drive which is switchable off with time delay in the "off" terminal position of the valve; a resilient member for limiting an increase in torque generated by kinetic energy of the rotary drive in the "off" terminal position; and a torque control for the rotary drive includes means defining a range of rotation of the rotary drive in both directions of travel thereof, the entire range of rotation corresponding to a stroke of the plug member and being subdivided into a starting range beginning at one terminal position and ending before a new terminal position is reached as well as into the remaining range; the rotary drive having an available starting torque (break-away torque), taking into consideration the tolerance limit of the power supply in the starting range downwardly, which is at least 10% higher than the largest torque applicable by the rotary drive,

Abstract: An automatic window regulator for automobiles includes a drive motor for lifting and lowering the window glass, and a detector for detecting when there is a foreign object jammed between the window glass as it is lifted or lowered and a window frame. The detector includes sensor means for measuring motor characteristic values of the drive motor and comparator means for comparing a first motor characteristic value measured by the sensor means with a second motor characteristic value measured by the sensor means a prescribed period of time prior to the first motor characteristic value and for generating a detected signal indicative of the jammed foreign object when any difference between the compared first and second motor characteristic values is greater than a predetermined range.

Abstract: An automatic door, driven with a motor and a speed sensor, is controlled with a servo device. Upon the door being opened or closed and being stopped by an obstacle or being out of order, the motor to drive the door will be stopped; in case of the door being retarded by a wind force or other factors, the driving power of the motor will automatically be adjusted to such an extent that the door can still be closed together so as to fully use the driving power of the motor.

Abstract: A device for preventing a motor from being locked comprises a position indicator for indicating a position to be moved in response to rotation of the motor, a position detector for detecting the position being moved in response to rotation of the motor, a servo control unit for supplying a current to the motor so that an output signal from the position detector will be equalized with an indication by the position indicator, a stop detector for detecting stoppage of the motor in response to a differential of the output signal from the position detector, and a cutoff control unit for cutting off the current supplied from the servo control unit to the motor in response to an output signal from the stop detector.

Abstract: A power window device has an arrangement to automatically invert the movement direction of a windowpane when an upward movement of the windowpane is prevented in the automatic drive mode by some reason before it reaches its proper upper limit, and also has an arrangement activated to invalidate the automatic inverting function of the arrangement for a predetermined time.

Abstract: An obstruction sensing and control arrangement for door or gate opening-closing mechanisms. The arrangement compares the operating rate of change of a predetermined characteristic with a preset rate of change and stops or reverses the motor in the opening/closing mechanism. The characteristic preferred is motor body temperature which is monitored indirectly. The control arrangement also includes a back up static control threshold to sense a second static operating characteristic of the motor and a second comparator means set at a preset threshold level to stop or reverse the motor. A common motor sensor is used for both the dynamic and static control thresholds. The invention also includes means to sense operating temperature and to alter the preset static threshold level automatically in response to temperature changes.

Abstract: A control circuit for a reversible D.C. window drive motor that allows for one touch operations of the motor to automatically lower the associated window to its full down position following a relatively short actuation of the control switch in the "DOWN" position. Subsequent actuation and release of the control switch will cause interruption and inhibit the automatic lowering of the window. Longer actuations of the control switch allows for direct movement control of the window in the downward direction. Stall current sensing and excessive time sensing provide protection to the motor and the drive circuitry.

Abstract: A drive circuit for servomotors that eliminates the need for microswitches to protect the motor when the system is driven to its limits of travel. The circuit monitors the current to the motor, identifies overload currents and terminates current flow to the motor when an overload occurs. The current flow is restored only when a reverse rotation command signal is received by the drive circuit.

Abstract: The present invention discloses a technique to avoid catching a foreign object in a power window by detecting overload of the window drive motor and stopping or reversing the rotation of the motor in response to said detection. The reference value for detecting overload is updated in accordance with a actual load of the motor in each predetermined time interval .DELTA.T but, in the present invention, when the start of an increase of overload is detected, the beginning of time period .DELTA.T is started again from that time, and thereby detection of overload is always carried out within the shortest period. Moreover, a variety of check mechanisms are also provided for ensuring the fail-safe function of the apparatus and for enhancing reliability of the protective apparatus.