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US 3,936,710 AGranted
Synchronous drive control system for dc motor
AssigneeCanon Kabushiki Kaisha
InventorKinji Tanikoshi
Life of this patent
Estimating the term…
Abstract
A system is provided to synchronously operate a DC motor in response to the frequency of a reference signal. The system includes a first feedback loop having a reference signal generator, a speed signal generator in relation to speed of the motor, and a flip-flop circuit for producing a rectangular wave pulse for supplying to the DC motor current corresponding to a phase difference between two signals from these generators. The system further includes a second feedback loop for speed control having a forced synchronization circuit which processes the output of the speed signal generator and brings the motor speed into a synchronization condition in order to prevent the motor from erroneously synchronizing.
Claims19
A DC motor and control system therefor comprising, in combination:
- a. a DC motor;
- b. motor-speed detecting means for detecting the rotational speed of said DC motor and generating an electrical signal having a frequency corresponding to the instantaneously changing rotational speed of said DC motor, said motor-speed detecting means being associatively arranged with said DC motor;
- c. means for generating a reference signal having a predetermined frequency in accordance with which said DC motor rotates at a predetermined constant speed;
- d. means for comparing said electrical signal and said reference signal to supply to said DC motor a potential corresponding to the phase difference of said signals;
- and
- e. control means inserted between said motor-speed detecting means and said comparing means to form an auxiliary feed back loop, said control means being arranged to produce a control signal operative to disable said comparing means only when the electrical signal frequency exceeds said reference signal by a predetermined amount and to interrupt said supply of the potential corresponding to the phase difference of said signals to said DC motor.
3 more elements
A DC motor control system comprising:
- a. a DC motor;
- b. means for generating a signal having a frequency corresponding to the speed of said DC motor;
- c. means for generating a reference signal having a predetermined frequency in accordance with which said DC motor rotates at a predetermined constant speed;
- d. signal comparing means for permitting current to flow to said DC motor in response to said reference signal and for interrupting said current flow in response to said DC motor speed signal, said signal comparing means being inserted between said signal generating means and said DC motor to form a first feed-back loop for motor speed control;
- and
- e. means for detecting the frequency of said DC motor speed signal and comparing the detected frequency with the frequency of said reference signal to produce a first control signal for disabling said comparing means only when said detected frequency exceeds said reference signal frequency and a second control signal for enabling said comparing means only when said detected frequency appears below said reference signal frequency, said frequency detecting and comparing means being inserted between said signal generating means and said comparing means to form a second feedback loop.
3 more elements
A DC motor control system comprising:
- a. a DC motor;
- b. means for generating a signal having a frequency corresponding to the speed of said DC motor;
- c. means for generating a reference signal of a fixed period for operating said DC motor at a predetermined reference speed;
- d. comparing means having applied thereto said signal having a frequency corresponding to the speed of said DC motor and said reference signal and being operative to supply a rectangular wave signal to said DC motor corresponding to the phase difference between said two signals;
- e. frequency detecting means connected to said motor speed signal generating means for detecting predetermined frequencies from said signal, said frequency detecting means having low and high pass filters with their cutoff frequency corresponding to said reference speed;
- and
- f. means for converting output signals from said two filters into respective step signals, said converting means being connected to said comparing means so that whenever the speed of said DC motor is shifting from a predetermined reference speed or coming out of synchronization, synchronous operation may be immediately restored.
4 more elements
A DC motor control system comprising:
- a. a DC motor;
- b. means for generating a signal having a frequency corresponding to the speed of said DC motor;
- c. means for generating a reference signal of a fixed period for operating said DC motor at a predetermined reference speed;
- d. comparing means having applied thereto said signal having a frequency corresponding to the speed of said DC motor and said reference signal and being operative to supply a rectangular wave signal to said DC motor corresponding to the phase difference between said two signals;
- e. control means inserted between said signal generating means and said comparing means to form an auxiliary feedback loop for controlling the motor speed, said control means being arranged to produce a first control signal for disabling said comparing means only when the electrical signal from said motor speed signal generating means exceeds said reference signal in frequency and to interrupt the supply of potential to said DC motor corresponding to the phase difference of said signals;
- f. means for detecting the disabled state of said comparing means;
- and
- g. means for damping said DC motor at the time of said disabled state.
5 more elements
A DC motor control system comprising:
- a. a DC motor;
- b. means for generating a signal having a frequency corresponding to speed of said DC motor;
- c. means for generating a reference signal of fixed period for operating said DC motor at a predetermined reference speed;
- d. comparing means having applied thereto said signal having a frequency corresponding to the speed of said DC motor and said reference signal and being operative to supply a rectangular wave signal to said DC motor corresponding to the phase difference between said two signals;
- e. control means inserted between said signal generating means and said comparing means to form an auxiliary feedback loop for controlling the motor speed, said control means being arranged to produce a first control signal for disabling said comparing means only when the electrical signal from said motor speed signal generating means exceeds said reference signal in frequency and to interrupt the supply of potential to said DC motor corresponding to the phase difference of said signals;
- and
- f. means inserted between said comparing means and said DC motor for smoothing the rectangular wave output signals from said comparing means.
4 more elements
Dependencies are inferred from the claim text.