Abstract: A hoist synchronization apparatus and method using a master controller operating software that provides a pulse reference to a slave controller. The slave commands its motor to rotate at the speed conveyed by that pulse reference. The slave controller monitors the pulse feedback from both the master encoder and the slave's encoder and compensates for any position error by adjusting its motor output speed. In addition, the slave controller includes the capability to automatically resynchronize the hoists. Resynchronization is accomplished by storing position error generated when either the master or the slave is run independently and correcting for the error when both units are operated at a later time.

Abstract: The simultaneous generation of interference currents with the same polarity is prevented in all converters of connected drives, without adversely affecting the time slice synchronization or the uniformity of the dynamic characteristics. This is achieved by taking advantage of the symmetry of the modulation. The triangles of the sinusoidal/triangular modulation do not overlap as in conventional drives; instead, the triangles of one group, corresponding to approximately half the number of drives, are offset by 180°. With control processes operating with phasor modulation, the offset of 180° represents a shift of the switching sequence by interchanging the initial zero phasors and/or the modulation half intervals.

Abstract: A load-driving circuit capable of driving a plurality of loads based on a priority order endowed therewith is provided. The load-driving circuit comprises a first load 3, a first driving switch 1 for driving the first load, a second load 4, a second driving switch 2 for driving the second load, first switching means 5 being turned on when the first driving switch is switched to a position where the first load is driven, second switching means 6 being turned on when the second driving switch is switched to a position where the second load is driven, and third switching means 7 for disconnecting the first load from the grounding terminal when the first switching means 5 and the second switching means 6 are turned on at the same time.

Abstract: A synchronous controller capable of easily controlling a slave axis in synchronism with a master axis performing a composite motion of a plurality of axes. Motion commands for two axes X, Y constituting the master axis are subject to interpolation/distribution and acceleration/deceleration processing, to determine distribution motion amounts, and the determined amounts of motion of the two axes X, Y constituting the master axis for every interpolation period are combined to determine an amount of motion M of the master axis, from which is determined an amount of motion of the slave axis for every interpolation/distribution period. The determined amounts of motion of the X, Y and slave axes are output to respective servo control means, thus driving the respective axes.

Abstract: A reference variable having a linear relationship with the angular position of a master axis is set, and a correspondence between this reference variable and the displacement of a slave axis is stored in a data table. One execution stage is specified by setting a starting reference variable and an ending reference variable from this data table. A desired sequence is assigned to a plurality of execution stages thus specified. The reference variable corresponding to the angular position of the master axis is determined, slave axis displacement data corresponding to the reference variable is read out, and the slave axis is positioned in accordance with the position of the master axis on the basis of this displacement data.

Abstract: The invention relates to method and apparatus for controlling the powering of electric drive motors (8) of a group of at least two machines (2, 3, 4), the motors operating in periodic motions, wherein the periodic motions are mutually coordinated in a manner so as to control a parameter which is representative of the operations of the machines. Parameters may include one or more of the sum of the electric power applied to the drive motors, the magnitude of the noise level generated by the machines and machine-caused vibrations. The drive motors of one machine may be controlled as a function of the periodic motion of the drive motor of the other machine, and power applied to one drive motor may be applied as a function of a mutually related drive motion of the machines.

Abstract: A synchronization device particularly for at least two windshield wipers, comprising at least two wipers, each of which is composed of a blade that is kinematically connected to an electric motor or gearmotor in order to oscillate between two preset positions; elements for activating/deactivating the gearmotor; elements for signaling the transit of each one of the blades through a preset reference position; elements for controlling the signals and driving the activation/deactivation elements; elements for determining the wiping time for each one of the wipers; elements for calculating the lead time error of the at least one wiper that is faster with respect to the slower wiper of the at least two wipers; elements for calculating a correction time; elements for identifying the slower wiper and elements for applying each one of the correction times to the corresponding motor/gearmotor of the at least one faster wiper.

Abstract: An underwater lighting fixture adapted for installation in a lamp receiving recess in the wall of a swimming pool. The fixture includes a lamp housing having a pair of reflector-mounted incandescent lamps mounted therein. A plate having a pair of a apertures is mounted in the housing with the apertures mounted in alignment with the lamps. A pair of secondary reflectors are mounted to face the plate apertures and are provided with light-transmitting portals. A color wheel having dichroic filter segments is mounted so that identically colored pairs of segments pass the portals when the color wheel is driven by a motor. The motor is controlled by a circuit by disconnecting power to an input of the circuit, reconnecting power to the input to control the motor to move at a first speed. The control circuit stops the motor when the driven element reaches an index position.

Abstract: A method of starting a brushless DC motor 12 at any initial speed (A) establishes a initial stator-field speed and setting a counter of synchronization, (B) measures a speed of a rotor of the motor, (C) compares the speed of the rotor with the stator-field speed to determine if the rotor is synchronized with the stator-field. If the rotor is not synchronized with the stator-field, the method includes (a) re-setting the counter of synchronization, (b) increasing an acceleration portion of motor current (Iacc) to enhance torque, (c) setting the stator-field speed higher than the rotor speed, (d) calculating a period of an open-loop timer, (e) calculating a value for a load portion of the motor current (Ild), where total motor current I=Iacc+Ild, (f) performing commutation based on the open-loop timer and returning to step (B) until the rotor is synchronized with the stator-field.

Abstract: A motor control system is provided for controlling at least one motor driven mechanical actuator. The control system drives the motor according to a function of the actuator position. The system is further arranged to modify the motor speed to ensure that a predetermined power limit is not exceeded.

Abstract: In order to provide a driving device for a motor having a capability equivalent to conventional vector control type sensorless method by simplifying the controls structure to reduce number of parts to be adjusted, and to stabilize the control system, a driving device for a synchronous motor does not include a speed controller or a current controller, and calculates a voltage impressed on a motor on coordinate axes (dc/qc axes) based on a magnetic pole axis. For calculating a voltage command, command values such as a rotation speed command and a current command are used, and Iq* corresponding to a torque current command is calculated and provided based on a detected current value.

Abstract: A direct-current power supply (40) is connected between the neutral points of two three-phase coils (24, 26) of a 2Y motor (22) constituted of the windings of the two three-phase coils (24, 26), which are connected in Y-connection and wound on a same stator, and to which three-phase alternating current power is severally supplied with a phase difference of a shifted angle between the windings from two inverter circuits (30, 32) having a positive pole bus (34) and a negative pole bus (36) for common use. A capacitor (38) is connected between the positive pole bus (34) and the negative pole bus (36). The electric potential difference between the neutral points of the three-phase coils (24, 26) is made larger or smaller than the voltage of the direct-current power supply (40) through the switching control of the inverter circuits (30, 32). Thereby, the capacitor (38) can be charged or discharged. Consequently, an inverter input voltage can be adjusted within a wide range.

Abstract: The simultaneous generation of interference currents with the same polarity is prevented in all converters of connected drives, without adversely affecting the time slice synchronization or the uniformity of the dynamic characteristics. This is achieved by taking advantage of the symmetry of the modulation. The triangles of the sinusoidal/triangular modulation do not overlap as in conventional drives; instead, the triangles of one group, corresponding to approximately half the number of drives, are offset by 180°. With control processes operating with phasor modulation, the offset of 180° represents a shift of the switching sequence by interchanging the initial zero phasors and/or the modulation half intervals.

Abstract: Method and system for controlling a synchronous machine including a polyphase stator are provided. The machine may be used in a piece of equipment respectively as a generator and as a motor for starting an engine in the piece of equipment. The method allows to sense rotor position of the machine using a sensor assembly configured to supply a respective stream of pulses indicative of rotor position relative to each phase of the machine. The method further allows to process each stream of pulses from the sensor assembly to generate a first set of inverter control signals. The first set of inverter control signals is applied to an inverter circuit coupled to energize the phases of the stator to start the machine. The first set of control signals is configured to provide a first cycle-conduction angle relative to the zero-crossings of the respective phase EMF voltages of the machine to produce a sufficiently high level of torque during start of the machine.

Abstract: A plurality of motors for use in driving accessories on a vehicle, are each powered by three-phase current. A single controller controls the supply three-phase current to the plurality of motors. In another aspect of the invention, pseudothree-phase current is created from a direct current voltage source. A chopping circuit chops the voltage into a plurality of pulses, and a phase shift circuit then creates phase-shifted power signals from those pulses. The present invention thus enables the use of three-phase alternating current motors on a vehicle to drive accessories. This reduces the cost and size of the required motors.

Abstract: An electromotive drive unit for an adjustable structure, for example a tabletop of a piece of furniture, includes at least one drive motor for adjusting a position of a structure. The drive motor includes a measuring unit for direct or indirect measurement of drive-specific parameters. A control unit is provided for controlling operation of the drive motor, and is acted upon by an evaluation unit for intervention in the adjustment process for the structure, when an actual value of the drive-specific parameters deviates from a desired value.

Abstract: A controller for motor/generators is proposed which allows reductions in ripple current generated by an inverter driving a power-generating motor/generator and a vehicle-driving motor/generator. The control device for motor/generators has a first inverter which supplies a control current to a first motor/generator used mainly as an electrical motor, a second inverter which supplies a control current to a second motor/generator used mainly as a generator, a first PWM signal generating circuit which drives the switching elements of the first inverter based on a first carrier signal, a second PWM signal generating circuit which drives the switching elements of the second inverter based on a second carrier signal which has the same period of the first carrier signal.

Abstract: It is an object of the present invention to prevent waste when printing is made on a paper web threaded through a detour web path from a printing unit to a folding unit via other printing units in such a manner that printing images are changed while the web is being transported by changing over a plurality of printing units through which the web is passed. The control section of each printing units having a detour web path is adapted so that it can produce a phase correction value so as to correct a drive reference speed signal with a signal relating to the difference between a drive reference phase and a corrected phase and a feedback speed signal.

Abstract: A network-type synchronous control system for rotary printing presses in which a driving means of a printing section P and the driven part thereof are combined into a block, and control is exercised so that several sets are brought into synchronous rotation by each set, the improvement comprising master control sections 1 and 2 that can independently control each of sets formed from arbitrary combinations of blocks, slave control sections 3 for controlling each block in the set upon receipt of control information from the master control sections 1 and 2, and a network line 5 connecting the master control sections 1 and 2 to each of the slave control sections 3: the master control sections 1 and 2 having a processing section, an input operation section for entering information, a master value setting section for setting a master phase and a master speed and a master network connecting section; so as to have a high degree of flexibility to ensure flexible response to the circumstances.

Abstract: A synchronization control device and a synchronization control method are provided in which it includes controllers Am and As1 of a master section and a slave section for accurately synchronizing rotational frequency and rotation phases of driving electric motors Mm and Ms1. The controller As1 includes rotational frequency detectors Ss1, Fs1, a master phase counter Cm1, and a slave phase counter Cs1, and detects at all times both of a rotational frequency and a rotation phase of the electric motors Mm of the master based upon an output of the rotary encoder Pm, and further detects at all times both of a rotational frequency and a rotation phase of the electric motor Ms1 of the slave.

Abstract: A gear pump having two meshing gears which are each assigned to a shaft and which are each driven by a driving unit. The driving units are controllable by a control unit such that the shafts rotate at a definable angular velocity. The control units having a symmetrical construction, and a control device provided in each control unit, each control device being connected to the other by way of a data line.

Abstract: An image forming apparatus has a plurality of drive motors for driving a plurality of photosensitive drums independently, a plurality of motor rotation controllers for controlling rotation and driving of the plurality of drive motors independently, a plurality of rotation phase detectors for detecting the rotation phase of each one of the plurality of photosensitive drums, a rotation phase difference calculator for calculating the rotation phase difference of the other photosensitive drums corresponding to the rotation phase of the photosensitive drum for black as the reference, a phase correction setting unit for setting the rotation phase difference in printing operation, and a phase correction controller for correcting rotation phase of the other photosensitive drums on the basis of the calculated rotation phase difference and the set rotation phase difference.

Abstract: A windshield washer control system for use on a vehicle is herein disclosed. The windshield washer control system for use on a vehicle having an occupant compartment with a windshield and a windshield wiper device. The wiper device is movable across a predetermined area of the windshield and the windshield washer device includes a sprayer and a sprayer nozzle. The windshield washer device is comprised of a windshield transparency detection system and a controller unit. The controller unit includes three operating modes. The first operating mode is defined by the windshield washer device being manually operable. The second operating mode is defined by the windshield washer device operating by cycle, wherein the windshield washer device is controlled to spray after a predetermined number of wiper cycles. The third operating mode is defined by the windshield washer device being automatically operable by using the windshield transparency detection system.

Abstract: A controller for a work transfer system, capable of performing precise positioning of feed bars during sole driving of the transfer system and simplified in structure to contribute to savings in installation space and cost. The controller has a cam angle detector mounted on a cam shaft for feed cams and controls servo motors for respective lift bars according to information which is related to cam angle of the feed cams detected by the cam angle detector and looked up in a motion table set by a transfer controlling PLC serving as a motion table setting means.

Abstract: A synchronization system according to the present invention includes a signal generator that provides a "RUN" signal simultaneously to two or more windshield wiper motors in response to simultaneous receipt of position signals generated by the motors. Each motor generates a position signal when the windshield wiper controlled by the motor is at a predetermined position. A gate circuit monitors the output of each motor to determine whether the motor is in the predetermined position. The gate circuit provides a trigger signal to the signal generator of the present invention only when each motor outputs a position signal. The trigger signal causes the signal generator to produce a subsequent "RUN" signal initiating another wipe cycle. Accordingly, the motors begin each cycle in synchronization.

Abstract: A torque controller system provides improved torque distribution as a function of wheel diameter size in a vehicle propelled by electric traction motors. The system includes one or more torque processors each having a multiplier coupled to receive an input signal and configured to produce an output signal which is the product of the input signal and a variable multiplier value generated by a respective torque distribution generator based on a predetermined torque distribution control function.

Abstract: A motor control apparatus, which can control the speeds of a plurality of motors with nearly no speed variations until the final target speed is reached, includes a target speed setting circuit for dividing the speed range of the motors up to the final target speed into n steps (n is an integer and n.gtoreq.2) to set a target speed, and setting the next divided target speed after all the motors have reached the current divided target speed.

Abstract: A CNC device 10 and servoamplifiers SA1, SA2 are connected in the manner of a daisy-chain. The positions of the servo motors M1, M2 detected by pulse coders P1, P2 are read in synchronization at the same point in time. In such circumstances, the synchronizing signal for the command to read the positions is propagated from the CNC device 10 to the servoamplifiers SA1, SA2 by means of transmission lines L1, L2. Propagation delay is generated, but synchronization is achieved by correcting this propagation delay time, so that the positions of the servo motors M1, M2 are detected at the same point in time.

Abstract: Synchronization of the drive bars of a servo transfer system is safely restored, while avoiding mechanical damage as much as possible.A synchronization position C for all the drive bars is determined from the respective present positions B of the drive bars and the respective deviations of the present positions B from the synchronization position C are determined. Then, servo motors for all the drive bars are so controlled that the drive bars move the distances corresponding to their respective deviations within the same period of time.

Abstract: A master-slave synchronization control system is constructed having two drive systems for driving respective ones of two controlled objects capable of being operated individually, wherein the drive system having the slower response is adopted as the master and the drive system having the higher response is adopted as the slave. The drive system of the master, which has the elements of a velocity control system that operates to follow up an entered velocity command value, outputs velocity information and position information of its controlled object. The drive system of the slave has a velocity control system in which the velocity information is adopted as the velocity command value, and a position compensating loop in which the position information is adopted as a position command value. The position compensating loop adds the position compensation value to the velocity command value as a correction signal.

Abstract: In a rotation synchronous control system comprising a host controller and a plurality of units connected to the host controller, each of the plurality of units having a rotation device, the system having a spindle sync function for the rotation devices to maintain a spindle sync between them, each of the units is provided with a spindle sync/reference signal source and a phase adjuster. The controller monitors the spindle sync between the units and issues a phase correction instruction to each of the units. Receiving the instruction, the phase adjuster in each unit adjusts the phase of the sync signal and uses the sync signal thus corrected to provide a spindle sync control.

Abstract: A drive control system for a binding line having first and second separate binding-line segments, includes a first motor for driving the first binding-line segment, a second motor independent of the first motor for driving the second binding-line segment, and a controller coupled to the first and second motors. The controller is operable in an independent or asynchronous mode for controlling the first and second motors so that the first and second binding-line segments operate independently, and is also operable in a synchronous mode for controlling the first and second motors so that the first and second binding-line segments operate in synchronism with one another.

Abstract: In a storage system using multiple disk drives, the disk drive spindles are rotated at the same frequency and at a predetermined phase relationship. A phase angle, measured as the difference between an index mark recorded on the disk and the disk's read head, is used to control the spindle rotation speed. Each of the disk drives are first independently frequency locked to a target frequency, and once frequency locked, each disk drive is phase locked in relation to one another. In the phase locking process, each disk generates a synchronizing signal for synchronizing the rotation of the disks to a predetermined phase relationship. If any one of the disk drives becomes inoperable (due to a failure or "hot-swapping"), the other disk drives remain synchronized since the synchronizing signal is not lost.

Abstract: A method and apparatus for controlling a machine in a power failure. The present invention is applicable to such machines that a tool and a workpiece must always be controlled in synchronization with each other, and allows the tool and workpiece to stop without any damage in the power failure situation. If a power failure occurs during a synchronous cutting operation, the present invention disables a power regeneration function, connects a discharge resistor unit to a DC link of a power regeneration circuit, decelerates motors for tool drive and workpiece drive in synchronization with each other, and retracts the tool back to a safe area by driving a motor for tool feed with the power regenerated from the other two motors.

Abstract: A drive control system for a binding line having first and second separate binding-line segments, includes a first motor for driving the first binding-line segment, a second motor independent of the first motor for driving the second binding-line segment, and a controller coupled to the first and second motors. The controller is operable in an independent or asynchronous mode for controlling the first and second motors so that the first and second binding-line segments operate independently, and is also operable in a synchronous mode for controlling the first and second motors so that the first and second binding-line segments operate in synchronism with one another.

Abstract: Methods and apparatus for switching a load between first and second sources is shown to include first and second solid state switches connected to the load. First and second mechanical breakers are connected between the switches and the sources so that each source is connected to the load through a circuit breaker and solid state switch. A controller is connected to sense the voltage from the first and second sources. The controller is connected to the first and second switches and the first and second mechanical breakers. The controller senses the phase difference between the voltages from the first and second sources. The controller causes the first and second mechanical breakers to open and close in response to sensing the phase difference between the sources. The first and second mechanical breakers can include medium voltage vacuum breakers.

Abstract: In a displacement machine for compressible media having at least two rotors (14a-c) which are configured as profiled bodies and whose profiles engage with one another in the manner of gearwheels during rotation, the individual rotors are respectively driven by their own electric motors (9a-c) and are kept synchronous in rotational speed and angular position by electronic closed-loop and/or open-loop control units (1; 25a-c) in accordance with the transmission ratio of the displacer unit stage. The electronics can be employed for monitoring further operating data of the pump and also for matching the pump output by changing rotational speed. It can also be used as an overload protection. The rotational speeds and rotational attitudes of the rotors are controlled individually and independently of one another, the required attitude values being specified to the individual control units (25a-c) by means of a main control unit (1).

Abstract: A method and apparatus for controlling a multiple motor drive arranged to drive printing cylinders of a printing machine sychronously decelerates each of the drives upon a failure or defect occurring in one or more of the components of the drive system such that the individual printing cylinders are decelerated in a manner synchronized with one another with respect to rotation angle. The apparatus includes a main control device which detects a failure in one of the drive system components and controls the drive units to decelerate the drive units to a standstill in accordance with a time function. The time function is determined by the rotation of the drive unit which contains the component that failed.

Abstract: A dual motor drive system particularly adapted for the drive of long printing presses provides uncoupled control of both the voltage and current provided to the motors. A current divider proportions the current provided to a main and secondary motor in accordance with a chosen ratio to maintain speed and torque in accordance with press requirements.

Abstract: In a rotation synchronous control system comprising a host controller and a plurality of units connected to the host controller, each of the plurality of units having a rotation device, the system having a spindle sync function for the rotation devices to maintain a spindle sync between them, each of the units is provided with a spindle sync/reference signal source and a phase adjuster. The controller monitors the spindle sync between the units and issues a phase correction instruction to each of the units. Receiving the instruction, the phase adjuster in each unit adjusts the phase of the sync signal and uses the sync signal thus corrected to provide a spindle sync control.

Abstract: A positioning apparatus and method for synchronously controlling a plurality of motors, such as servo motors, and exercises synchronous control by means of only motors without using any mechanisms, such as coupling shafts, clutches, gears and cams. A controller has a virtual drive capability which provides a virtual cam and virtual clutch capability on the basis of stored values, permitting continuous and repeated operation of a single cycle of positioning with respect to changes in input axis position address data without recalculation of command addresses in real time.

Abstract: In a linear feedback servo control system, the motion profile for each axis is pre-filtered before it is introduced to the servo loop for that axis. The motion profile is pre-filtered by a filter having an inverse amplitude response to the amplitude response of the servo loop. Therefore, the composite amplitude response of the filter/servo loop combination is approximately ideal for all relevant frequencies. The pre-filtering is done using constant delay filters, whether high pass, low pass or hybrid, that exhibit a phase lag corresponding to a time delay that is essentially constant at all relevant frequencies. Each axis of synchronized motion is pre-filtered with constant delay filters having the same time delay constant, but selected so that the motion of each axis provides sufficient accuracy within the intended bandwidth of that particular axis. Consequently, while phase lag is not zero, there is essentially constant delay for all axes at all relevant frequencies.

Abstract: Two windshield wiper blades are powered by separate electric motors. The blades overlap and when one blade is at its reversal point the other blade leaves part as the other blade begins to return to park. The position of the blades is encoded. The blades, if synchronized should be at identical locations and position codes at the same time. Motor power to the blade that arrives first is be removed, allowing the blade to coast. If the other blade still does not arrive at the position after an elapsed time, the first to arrive blade is dynamically braked. Intermittent wiper operation is provided in a way that initiates an immediate wipe if wiper delay is changed while the blades are parked.

Abstract: In order to bring and keep a slave phase of rotation of a slave spindle into and in synchronism with a master phase, the master phase is represented in a predetermined time duration by zeroth through (N-1)-th master region data with an N-th master region datum added, where N represents a predetermined integer which is not less than two. The slave phase is represented, during one rotation of the slave spindle, by zeroth through (N-1)-th slave region data with an N-th slave region datum additionally used to provide a guard time. The zeroth through the (N-1)-th slave and master region data are compared to render a phase difference between the master and the slave phases either to zero or to a predetermined value. Alternatively, the master phase is represented in the predetermined time duration by a sequence of composite pulses which comprise N master clock pulses with at least one of the clock pulses omitted to indicate a start point of the sequence.

Abstract: A system for synchronizing a plurality of motors is disclosed. The system includes a universal drive controller which can control the operation of two motors, a power module for each motor, and a power module interface rack which is utilized to interconnect the motor to its associated universal drive controller. If a plurality of universal drive controllers is involved, a common clock is utilized to synchronize the operation of same.Synchronization of the motors is achieved by monitoring the output shaft of each motor through the use of a resolver, transmitting feedback data relative to the position of the output shaft to the universal drive controller via the power module interface rack, calculation of command data by the universal drive controller to effect synchronization, and transmitting the command data to the power module interface rack wherein the power module causes the proper firing signals to be transmitted to the associated motor.

Abstract: A method and apparatus for controlling speed match between a photoreceptor and an intermediate transfer member to prevent image degradation by creating a deliberate speed mismatch. It has been found that slight variations in speed match between a photoreceptor and transfer member will maintain acceptable image quality, however, should the relative velocity between the members change sign, unacceptable image error results. The method herein comprises slewing the velocity of a photoreceptive member over a range of speeds while monitoring the output control signal current of a drive motor. The resulting control signal current has a large oscillation at the velocity at which the speed of the photoreceptor matches that of the intermediate transfer member. A controller is then used to maintain the motor velocity at a speed slightly less than or slightly greater than the intermediate transfer member speed so as to prevent a change in sign of the relative velocity between the two moving surfaces.

Abstract: In a synchronous operation system, rotating positions of two rotating elements MSP and SSP driven by induction motors IM.sub.1 and IM.sub.2 are maintained in a predetermined positional relation, what is called, a synchronous control by a position adjuster 7. A gain compensating circuit 10 for adjusting an output of the position adjuster 7 by using a detected speed of one rotation element SSP as a parameter is provided, and the gain compensating circuit 10 adjusts the output of the position adjuster 7. Thus, a slippage of the induction motor is compensated in a speed region where the position variation of the two rotating elements becomes excessively large, or in a high speed region (constant output region) exceeding a basic rotation speed in case the synchronous control is carried out by using an induction motor and an invertor for controlling a primary frequency of the induction motor.

Abstract: In a color image forming apparatus such as a color laser printer, misregistration of colors of an output image along a subscanning direction is minimized so as to prevent accumulation of color misregistrations in the output image. In the apparatus, a photosensitive drum motor and a transfer drum motor are driven by motors exclusively provided thereto. The apparatus includes a photosensitive drum motor controller and a transfer drum motor controller respectively provided for speed-controlling the photosensitive drum motor and the transfer drum motor. By these motor controllers, a phase difference between a frequency generator signal from the motor and a phase reference signal is checked. Even if the phase difference exceeds a predetermined range of phase, the motor controller controls the motor so that the phase difference quickly falls within the predetermined range of phase.

Abstract: A hard disk drive spindle synchronization method comprises the steps of: sending an index marker pulse generated within each disk drive to mark in time a beginning of each rotation of the disk spindle thereof to a party line to which all drives are connected, rotating the disk spindle at a slightly different rotational velocity than any other drive of the array, monitoring drive pulses present on the spindle reference party line from other disk drives of the plurality to locate a center of gravity of pulse clusters which is within approximately plus or minus one quarter revolution of the drive's own index marker pulse, upon detection of a said center of gravity, ceasing to rotate the disk spindle at a slightly different rotational velocity during a second phase, adjusting the rotational phase of each drive to converge toward the center of gravity until all drive pulses present on the spindle reference party line converge into a single composite marker pulse present on the spindle reference party line, and mai

Abstract: A synchronous rotating apparatus synchronously rotates a plurality of rotary shafts independently driven by corresponding driving devices. The apparatus includes: a mechanical regulating member, arranged on the shafts, for maintaining relative rotating positions of the shafts at a predetermined angular difference; a rotation velocity and phase-detecting member, arranged on each shaft, for detecting rotation velocities of the shafts and phases within a regulated angular difference of the regulating member, and a driving control device for controlling the driving devices of the shafts so as to synchronously rotate the shafts based on a phase difference detected by the detecting member. The apparatus is applied to a fluid rotary apparatus.