Did You Know...
...that the x-ray was discovered purely by accident? When German physicist Wilhelm Konrad von Roentgen was experimenting with cathode rays in 1895, he put an activated Crookes tube in a book and went out to lunch. When he returned, he discovered that a key that had also been placed in the book showed up as an image on the developed film!
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| Number | Title | Issue Date |
| 7412156 | Brushless DC motor driver circuit capable of reducing vibration or shock noise and method thereof The present invention discloses a brushless dc motor driver circuit capable of reducing vibration or shock noise and a method thereof. The brushless dc motor driver circuit of the present invention comprises a Time-Voltage Digital/Analog Converter. The Time-Voltage ... | 08/12/2008 |
| 6977477 | Systems, apparatus, and methods for motor control Systems and methods are provided through which the current to a spindle motor of the recording medium of a mass storage device is modulated to avoid anomalies in the operation of mass storage device and reduce power consumption. In the example of a disc drive, the c... | 12/20/2005 |
| 6859001 | Torque ripple and noise reduction by avoiding mechanical resonance for a brushless DC machine A method of reducing torque ripple and noise for an brushless DC machine comprising: determining a control frequency for the electric machine, the control frequency indicative of an existing current command to and a rotational velocity of the electric machine; multi... | 02/22/2005 |
| 6586904 | Compensation for variable voltage A switched reluctance drive is supplied from a voltage source which varies from the voltage at which the control laws for the drive were determined. The control system compensates for this by modifying both the speed and torque values used to determine th... | 07/01/2003 |
| 6225770 | Method for the control of motor driven adjustment devices in motor vehicles High resolution and accuracy of the measured values for detection of the position, speed and/or acceleration of a drive is ensured. The tolerances are determined and considered in signal evaluation on a partitioned basis. Measurement errors caused by inac... | 05/01/2001 |
| 5955799 | Linear vibration motor and method for controlling vibration thereof A linear vibration motor which includes a vibration system, an electromagnetic driver, a detection system, and a control system. The vibration system includes a driven member or reciprocator which is mounted to a magnetic member for reciprocating movement... | 09/21/1999 |
| 5773945 | Time-compensated overcurrent detection circuit for DC motor A time-compensated overcurrent detection circuit shuts off a D.C. motor during large overcurrent conditions caused by actual constraints on the motor. The circuit prevents premature motor shut off by establishing a minimum activation time for shutting off... | 06/30/1998 |
| 5737483 | Motor speed control apparatus for motors A motor speed control apparatus is provided in which the controllable frequency band of the control system can be sufficiently enhanced with a comparatively simple structure even if the frequency generator equipped into the motor is low in output frequenc... | 04/07/1998 |
| 5724477 | Compensation for input voltage variation in an electric motor drive The present invention employs digital circuitry to compensate for variations in DC link voltage transmitted to a switched reluctance machine. The digital voltage compensation system of the present invention periodically samples the DC link voltage and act... | 03/03/1998 |
| 5682459 | Speed control for controlling the speed of a DC motor A speed control for controlling the speed of a DC motor provides improved speed regulation during transient loading conditions. The control includes a regulating circuit having an output for controlling the armature voltage to the motor, An input speed re... | 10/28/1997 |
| 5664048 | Speed control circuit for a DC motor A speed control circuit for a DC motor includes a digital-to-analog (D/A) converter, a regulator/controller, and a control circuit which applies a compensating current to the DC motor that compensates for variations in loading applied to the motor. The re... | 09/02/1997 |
| 5652491 | Position controller for an electric motor A position controller includes: a compensation torque control circuit which outputs a second torque signal T2 * and an initial value of an integration torque Tiset on the basis of a real speed signal ωM, a rotation angle ... | 07/29/1997 |
| 5590236 | Speed controller or an instrument having a speed controller including detection means for linearly detecting the amount of rotation less than one full rotation of a rotating member A speed controller includes a drive source, an input device for inputting the driving speed information of the drive source, a driver for driving the drive source on the basis of the driving speed information input by the input device, a detector for line... | 12/31/1996 |
| 5570304 | Method for thermal modeling and updating of bias errors in inertial navigation instrument outputs A method for thermal modeling and updating of bias errors in inertial navigation instrument outputs relies upon piecewise cubic spline encoding of data. The temperature range of the thermal model is divided into contiguous intervals of equal length. Instr... | 10/29/1996 |
| 5539852 | Method for controlling speed in a tape feeding, cutting and ejection apparatus for a mailing machine A method for controlling the speed of a motor for a tape drive in a mailing machine includes providing an optical sensor for signaling the appearance of slots in a slotted wheel connected to the motor shaft. The time intervals between slots are used to ma... | 07/23/1996 |
| 5521481 | Speed estimation observer applied to speed control system for motor A speed estimation observer for a motor control system outputs a motor speed estimate in a motor speed control system upon receiving a torque command and an averaged motor speed value. The speed estimation observer includes a time lag correction value cal... | 05/28/1996 |
| 5469215 | Method and apparatus for controlling an electric motor with compensation or torque ripple An electric motor control system compensates torque ripples to control the rotation of an electric motor more accurately. Compensated current amplitudes corresponding to the torques, speeds and rotational positions in the electric motor are stored in a me... | 11/21/1995 |
| 5392378 | Speed controlling system and a predictor A predictor (20) and a learning device (20) are newly provided to a conventional speed controlling system for a rotating body, according to the present invention. The predictor predicts an instantaneous speed error on the basis of a plurality of speed err... | 02/21/1995 |
| 5377295 | Speed controller of motor Disclosed is a speed controller of a motor which comprises a rotation sensor for generating an A.C. signal having a period in accordance with a rotating speed of a motor; speed detection device for effecting detection operations a plurality of times per r... | 12/27/1994 |
| 5367600 | Motor control for a treadmill having improved power supply and improved speed regulation under intermittent loading A motor control for a treadmill has an improved, inexpensive, and simple set of power supplies, derived from the bus voltages of the DC busses with simple voltage dividers, to supply operational amplifiers connected to the positive DC voltage bus with a d... | 11/22/1994 |
| 5351336 | Motor control having improved speed regulation under intermittent loading A control for energizing a DC motor to provide improved speed regulation to the motor under transient conditions. The control includes a regulating circuit having an output signal controlling the armature voltage applied to the motor. An input speed refer... | 09/27/1994 |
| 5323096 | Servomotor control device using servomotor rotation speed extrapolation A servomotor control device including a drive pulse generating circuit for generating a pulse signal having a frequency corresponding to an actual frequency of a servomotor, and arithmetic operation unit for outputting a control signal on the basis of the... | 06/21/1994 |
| 5317668 | Motor control device for controlling motor speed depending on imparted load For operating a plurality of mechanisms with a single motor, a motor control device is provided which is capable of stably operating one of the mechanisms while reducing influence of load imparted on the motor and attributed by an operation of remaining o... | 05/31/1994 |
| 5223775 | Apparatus and related method to compensate for torque ripple in a permanent magnet electric motor An input control current command signal is modified in accordance with a number of compensation factors stored in a memory and corresponding to each of a number of angular shaft positions to provide a control signal to cause an inverter to drive each of t... | 06/29/1993 |
| 5220266 | Motor speed controlling device capable of correcting for speed detection error caused by change of duty ratio of photocoupler output pulses A motor speed controlling device controls the rotational speed of a motor by feeding back an actual rotational speed detected by a photocoupler. An encoder disk formed with equi-pitch slits in the periphery thereof is attached to the drive shaft of the mo... | 06/15/1993 |
| 5167002 | Electric motor driver control An apparatus and method for reducing synchronous speed variations in an electric motor having a rotating shaft, comprises a speed transducer for generating a continuous analog speed signal corresponding to the speed of the motor shaft including its synchr... | 11/24/1992 |
| 5155797 | Control system for controlling revolution speed of electric motor A motor speed control system takes one approach to establish dummy load models having characteristics equivalent to an electric motor to be controlled. One of the dummy load models is established for feedback controlling the electric motor on the basis of... | 10/13/1992 |
| 4969757 | Motor torque control A motor torque control assembly is provided which can automatically adjust the motor torque so that its reaction torque remains substantially constant, and so that the reaction torque is not changed by changes in motor internal variables, such as bearing ... | 11/13/1990 |
| 4950090 | Method for the detection and regulation of a spring moment and a difference speed in rotationally driven two-mass systems A method for the detection and regulation of a spring moment and a difference speed in rotationally driven systems in which a drive unit can be viewed as an elastically coupled two-mass system. The spring moment and the difference speed are determined wit... | 08/21/1990 |
| 4839570 | Current limiting control circuit for d.c. motors A current limiting control circuit for a d.c. motor, wherein compensation is provided for the inherent voltage drop across the armature of the d.c. motor with a first dedicated amplifier, while a second dedicated amplifier provides current limit control. ... | 06/13/1989 |
| 4837486 | DC motor speed stabilizing method and apparatus The speed of a DC motor is stabilized to correspond to a reference speed by a motor driving control that is instantaneously responsive to the interval between reference pulses corresponding to the reference speed and actual observed pulses corresponding t... | 06/06/1989 |
| 4833377 | Current leakage reduction circuit An offset current which is 180° out of phase with the leakage current for a motorized bed circuit is created through the use of an additional transformer winding and series resistor which is connected between the neutral conductor and ground conductor. A... | 05/23/1989 |
| 4831312 | Speed control device for d-c motors A speed control device for d-c motors includes an IC control circuit having such a construction that a reference voltage is generated across two of its terminals C and D. Additionally, a current proportional to the armature current of the d-c motor is kep... | 05/16/1989 |
| 4829230 | Motor control circuit for accurate speed control with capacitor leakage compensation A slow start motor control circuit for applications wherein extremely accurate speed control is required, such as, in a centrifugal blood separator application is disclosed. In a blood separator, the degree of separation of cellular components, such as re... | 05/09/1989 |
| 4827202 | Method of and circuitry for automatically adjusting the variable-gain amplification in a control loop In a control loop for automatically adjusting variable-gain amplification, a sinusoidal signal with a frequency fo that is critical for the control loop is superimposed over a positioning parameter W. Two synchronous rectifiers S1 and S2 filter... | 05/02/1989 |
| 4803409 | Acceleration signal corrected motor speed control system The speed of a motor supported on a supporting base the position of which is changed during operation of the motor is controlled by use of a detector for detecting the degree of angular acceleration of the motor supporting base in a plane normal to the sh... | 02/07/1989 |
| 4801855 | Method and system for controlling chopper The magnitude of current change for the change of input voltage or for the change of speed of rotation of the shunt motor is utilized, i.e., the shunt characteristics are utilized, and the voltage applied to the motor is limited so that the armature curre... | 01/31/1989 |
| 4764711 | Back emf loop closure The back emf voltage of a motor is extracted from the applied motor voltage and motor current by means of a control system including a back emf sensor, an adaptive motor resistance circuit, and a position integrator. In the back emf sensor a corrected mot... | 08/16/1988 |
| 4752851 | Overload protection for series resistances of electric motors, especially of fans of vehicles driven by electric motors Overload protection for the series resistance of an electric motor in which a voltage drop across the electric motor is monitored. During the occurrence of a reduced voltage drop, for example, as a result of a blocking of the motor or of a fan driven by t... | 06/21/1988 |
| 4752723 | Chopper control system A chopper control system for a vehicle driven by a shunt motor. The system is provided with an integrating circuit for generating a command value for the voltage which is to be supplied to an armature of the motor in accordance with the difference between... | 06/21/1988 |
