Famous Patents
3M employee and church chorister Art Fry needed something to temporarily mark pages in his hymnal. He was in luck because his colleague, Spencer Silver, accidentally developed a glue that was too weak for other purposes. After initially discouraging consumer response, Post-it Notes became a hit in 1979.
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| Number | Title | Issue Date |
| 7279857 | System, method, and computer-readable medium for reduction of commutation-related acoustic noise in a fan system A method for reducing commutation-related acoustic noise in a fan system is provided. A constant frequency periodic signal is generated and a fan commutation event is synchronized with a zero level value of the constant frequency periodic signal. A system for contro... | 10/09/2007 |
| 7183731 | Pulse generating method and pulse generator, and motor control system using the same A method of generating pulses includes setting a cycle based on a frequency of reference clock, determining a total number of the pulses to be generated during the cycle, calculating the number of one or more first reference clocks used to determine a width of one o... | 02/27/2007 |
| 7164244 | Apparatus for controlling electric motors and related control method An electric motor controller controls the currents flowing through the phase windings of an electric motor. The electric motor controller includes driving stages for driving respective phase windings of the motor and a memory for storing samples of reference signals... | 01/16/2007 |
| 6995531 | Direct current motor drive circuit and fan motor including the same A direct current motor drive circuit comprises: a hall element; an H-bridge drive circuit which receives an input of a sinusoidal signal outputted from the hall element and outputs rectangular wave signals corresponding to the sinusoidal signal; a dead time circuit ... | 02/07/2006 |
| 6693407 | Controller and associated system and method for pulse-width-modulation switching noise reduction by voltage control A system for controlling a brushless direct current (BLDC) motor includes a power supply having a controllably alterable voltage output, and a controller in electrical communication with the power supply and the motor. The controller receives the voltage ... | 02/17/2004 |
| 6518723 | H-bridge motor driving circuit An H-bridge motor driving circuit has, between a PWM comparator and a control circuit, first and second frequency dividers for frequency-dividing, by 2, an AND gate, OR gate, and first and second and second inverters. During a first period, the first and ... | 02/11/2003 |
| 6392373 | Automatic reverse motor controller A method and apparatus to automatically reverse the motor of a dispensing gun or similar tool. The invention includes a controller that automatically reverses the direction of plunger movement and removes the plunger from contact with the back wall of a c... | 05/21/2002 |
| 6013991 | Motor control circuit A motor controller for regulating the application of current to the windings of a motor in order to both control the actuation of the motor rotor and the braking of the rotor. The motor controller includes a speed control circuit regenerating a signal rep... | 01/11/2000 |
| 5812428 | Process controller having non-integrating control function and adaptive bias A process controller controls an integrating-type process based on a measured process variable and a set point. The process controller includes an error generating circuit, a non-integrating control circuit and an adaptive bias circuit. The error generati... | 09/22/1998 |
| 5747953 | Cordless, battery operated surical tool A powered surgical tool includes a motor, a motor control module for controlling the actuation of the motor, and a trigger assembly for allowing the user to enter user-selected commands indicative of desired motor rotation. The trigger assembly includes a... | 05/05/1998 |
| 5410236 | Device to regulate the speed of an electric motor and its method of operation Digital device to regulate the speed of an electric motor having a commutating element mounted in series with the motor at the terminals of an A.C. distribution network. A duration of an on-state of the commutating element defines values corresponding to ... | 04/25/1995 |
| 5367236 | DC motor stall-detection system A motor controller is programmed for detecting motor-stall condition of a dc motor under the control of a motor control system. The motor control system includes a programmable microcontroller in connection with the motor controller and a motor driver. Th... | 11/22/1994 |
| 5298841 | Apparatus for controlling the speed of a moving object A speed control apparatus in which for sampling features of a speed fluctuation and generating a speed fluctuation correcting signal, an arithmetic operation can be simplified and can be performed by an inexpensive arithmetic and operation unit, thus requ... | 03/29/1994 |
| 5059992 | Drive device for motor In a motor control device, an electric circuit responsive to a mode selection signal for determining whether or not an electric motor is driven is constructed with two field-effect transistors. A source terminal of the first field-effect transistor is con... | 10/22/1991 |
| 4855652 | Speed control apparatus for a brushless direct current motor AC power supply is converted to DC by a rectifier circuit. The DC is stepped up by a step-up chopper circuit. The output of the step-up chopper circuit is smoothed by a smoothing circuit. The output of the smoothing circuit is input to an inverter via a c... | 08/08/1989 |
| 4851744 | Feedback circuitry for D.C. motor speed control A circuit for controlling the speed of a DC motor provides delay and sampling means in the feedback loop to delay the triggering of the SCRs driving the DC motor and measured the motor armature voltage during the period of the delay, thereby eliminating e... | 07/25/1989 |
| 4828395 | Continuous flow type homogenizer There is provided a continuous flow type homogenizer. The homogenizer comprises, a tubular container having at upper end thereof an inlet for introducing tissue to be homogenized and at lower end thereof an outlet for discharging the homogenized tissue, a... | 05/09/1989 |
| 4794310 | Phase angle control circuit for motors A control circuit for d-c motors, which are supplied by an a-c supply through phase angle control, and which obtains information regarding the actual current value from a current transformer secondary voltage, and which is utilized additionally also for d... | 12/27/1988 |
| 4734629 | Variable speed trigger switch A variable speed trigger switch particularly adapted for use with electric power tools such as drills. The trigger switch features clam shell construction and a single vertically disposed circuit board thereby facilitating assembly and resulting in a low ... | 03/29/1988 |
| 4636935 | Power control system A solid state control device is disclosed for controlling power turn-on times to process systems such as heaters used in glassmaking, in petrochemical plants, in furnaces, and for electromotive, and other devices. A command signal from the process control... | 01/13/1987 |
| 4617675 | Digital PWMed pulse generator Plural series of digital pattern data are determined by PWMing a sine wave by a triangular wave and further classified into each series by the number of triangles included within a half cycle of the sine wave. An appropriate series of data are selected ac... | 10/14/1986 |
| 4567408 | Digitally controlled rectifying system for driving a motor A digitally controlled rectifying system used for driving a d.c. motor through antiparallel connected forward and reverse converters. The firing phase angle of the converters is shifted by 180° at a time of gate switching operation for the converters so ... | 01/28/1986 |
| 4554964 | Method for controlling temperature of water to be fed into water cooling tower A method for controlling the temperature of water to be fed into a water cooling tower in which when the driving power required to drive motors to be controlled is in excess of the power which can be derived from a frequency converter, some of the motors ... | 11/26/1985 |
| 4454459 | Method of controlling the speed of a drill, hammer-drill, or rotary hammer and apparatus therefor The invention is directed to a method and apparatus for controlling the speed of an electronically controlled drill, hammer-drill or rotary hammer driven by an electrical motor wherein the rotational speed is first raised from zero to a predetermined star... | 06/12/1984 |
| 4412158 | Speed control circuit for an electric power tool A method and apparatus for controlling the rotational speed of an electronically controlled power tool in both the forward and reverse direction. When the reversing switch is placed in the reverse direction, the electronic speed control circuit automatica... | 10/25/1983 |
| 4394606 | Speed control circuit for electric motor Disclosed is an apparatus for controlling the rotational speed of an electric motor based upon the load encountered by the electric motor. A load sensor provides a voltage level based upon the operating load of the electric motor and accumulates this volt... | 07/19/1983 |
| 4348622 | DC Motor drive control system A DC motor drive-control system with a driver circuit for energizing the DC motor receiving a command signal to the driver circuit to cause the motor to rotate in accordance therewith. An encoder is coupled with the DC motor so as to respond to an angular... | 09/07/1982 |
| 4311949 | Semiconductor circuit for speed control of electric motors A digital control loop is provided in which analog signals supplied by a tachometer, driven by an electric motor, are digitally evaluated, that is are compared with a reference value existing in digital form, and a deviation from the reference is employed... | 01/19/1982 |
| 4307325 | Digital control system for electric motors in power tools and the like A digital control system for electric motors in power tools of the portable or stationary type includes a microcomputer controlled speed regulator connected to the electric motor for maintaining a preselected speed of the motor substantially constant betw... | 12/22/1981 |
| 4152758 | Control logic for a phase controlled rectifier system Apparatus for providing firing signals to a phase controlled rectifier circuit at a time at which valves in the rectifier circuit are forward biased without the need for providing continuous firing signals. The apparatus monitors the voltage applied acros... | 05/01/1979 |
| 4121142 | Full-wave bidirectional DC motor drive circuit The present invention is a DC motor drive circuit in which each end of a center tapped supply transformer is connected through a pair of back-to-back thyristors to corresponding ends of a center tapped choke coil. The motor armature is connected between t... | 10/17/1978 |
| 4096422 | Motor control system The duty cycle of the alternating current waveform applied to an electric motor is varied by varying the firing point of an SCR circuit. This firing point is varied by logic circuitry which responds to the largest (or smallest) output of several integrato... | 06/20/1978 |
| 4031438 | Control device for the rotary motor of a watch A control device for the motor of a watch including first and second zero detectors and a delay device for providing gating signals to an AND gate to enable transmission of driving in phase with the a.c. voltage induced in the coil. BACKGROUND OF THE INVE... | 06/21/1977 |
| 3984868 | Tape speed control apparatus for magnetic tape device Improved apparatus for controlling tape speed in a reel-to-reel magnetic tape transport system. A controllable reel drive motor operates in response to a control signal derived from an accumulated count of reel revolutions so that the driven reel is drive... | 10/05/1976 |
