Speed control device for direct current motors

Claim 2

A speed control system for a direct current motor, comprising a DC tacho-generator for generating a speed indicating signal normally proportional to the speed of the motor, signal level adjusting means for producing an output proportional to the signal generated by said DC tacho-generator, reference means for forming a reference signal, differential amplifier means having a first input terminal connected to the output from said adjusting means and a second input terminal connected to the signal from said reference means producing an error signal that corresponds to a difference between the output of said adjusting means and the signal from said reference means, waveform-producing means for producing a varying signal of a predetermined wave shape, comparison means responsive to said waveform-producing means and the error signal from error signal-producing means for comparing the error signal with the wave shape of said waveform-producing means for producing pulses which last as long as the relationship between the wave shape and the error signal is in one range and outside another, switching means coupled to said comparison means and responsive to the pulses therefrom for producing driving pulses having pulse widths determined by said comparison means, the speed indicating signal departing from normal proportionality to the motor speed in response to changes in temperature, said reference means having a constant voltage circuit including a constant voltage circuit including series-connected diodes which departs from a constant value at a rate corresponding to the rate at which the speed indicating signal departs from proportionality to the motor speed.

Claim 3

A system as in claim 1, wherein said temperature compensating means includes a diode arrangement whose characteristic varies the voltage thereacross according to the departure of the speed indicating signal from normal.

Claim 4

A system as in claim 2, wherein said signal generator means includes a tacho generator connected to said motor for generating the speed indicating signal.

Claim 5

A system as in claim 2, wherein said error level adjusting means includes a differential amplifier having two amplifying devices with respective input terminals, one of said input terminals being connected to said reference means.

Claim 6

A system as in claim 1, wherein said switching means includes a control voltage source for producing the pulses with substantially equal amplitudes.

Claim 7

A system as in claim 2, wherein said switching means includes a control voltage source for producing the pulses with substantially equal amplitudes.

Claim 8

A system as in claim 4, wherein said reference means includes reference voltage-adjusting means connected to said reference voltage applying circuit to permit the level of said reference signal to be subjected.

Claim 9

A system as in claim 2, wherein said waveform-producing means includes generating means for producing a waveform having a rising portion and a declining portion, said portions being substantially linear.

Claim 10

A system as in claim 8, wherein said waveform-producing means produces a signal having a frequency higher than the frequency of which the motor is capable of responding.

Claim 11

A system as in claim 8, wherein said generating means in said waveform-producing means produces a saw-tooth waveform.

Claim 12

A system as in claim 8, wherein said generating means in said waveform-producing means produces a triangular waveform.

Claim 13

A system as in claim 2, wherein said waveform-producing means produces a sine wave.

Claim 14

A system as in claim 2, wherein said comparison means includes a differential amplifier circuit for differentially comparing the error signal with the signal from said waveform-producing means, said differential amplifier including a pair of common-emitter connected transistors of the same polarity, one of said transistors having a base connected to said adjusting means, the other of said transistors having a base connected to said reference means.

Claim 15

A system as in claim 1, wherein said switching means includes a switching transistor connected in series with said motor and responsive to said comparison means.

Claim 16

A system as in claim 1, wherein said switching means includes a constant voltage source and a switch connected in series with said motor, said switch producing pulses in response to said comparison means.

Claim 17

A speed control system for a direct current motor, a tacho generator coupled to the motor for producing a speed indicating signal normally proportional to the speed of the motor but variable with temperature, reference means for producing a reference signal, differential amplifier means responsive to the tacho generator in the reference means for producing an error signal in response to the relationship between the speed indicating signal and the reference signal, generator means for producing a signal having a predetermined rising and falling wave shape, modulating means responsive to said error signal for producing a pulse signal having a plurality of pulses whose pulse durations vary with the level of said error signal, said modulating means including a comparing circuit responsive to said reference means and said differential amplifier means for comparing said error signal with the signal having the predetermined wave shape, switching means responsive to said modulating means for providing power pulses to vary the power to the motor on the basis of the widths of the pulses, and motor speed control means, said motor speed control means including signal level adjusting means between said signal generator means and said reference means for varying the proportionality of the signal applied to said amplifier means to the speed of the motor so as to vary the speed of the motor, said reference means including a constant voltage diode and a temperature compensating diode arrangement having a characteristic corresponding to the temperature induced speed indicating signal variations so as to compensate for the variations, wherein said differential amplifier means has a first input terminal connected to said signal level adjusting means and a second input terminal connected to said reference means.

Claim 18

A speed control system for a direct current motor, a tacho generator coupled to the motor for producing a speed indicating signal normally proportional to the speed of the motor but variable with temperature, reference means for producing a reference signal, differential amplifier means responsive to the tacho generator in the reference means for producing an error signal in response to the relationship between the speed indicating signal and the reference signal, generator means for producing a signal having a predetermined rising and falling wave shape, modulating means responsive to said error signal for producing a pulse signal having a plurality of pulses whose pulse durations vary with the level of said error signal, said modulating means including a comparing circuit responsive to said reference means and said differential amplifier means for comparing said error signal with the signal having the predetermined wave shape, switching means responsive to said modulating means for providing power pulses to vary the power to the motor on the basis of the widths of the pulses, and motor speed control means, said motor speed control means including signal level adjusting means between said signal generator means and said reference means for varying the proportionality of the signal applied to said amplifier means to the speed of the motor so as to vary the speed of the motor, said reference means including a constant voltage diode and a temperature compensating diode arrangement having a characteristic corresponding to the temperature induced speed indicating signal variations so as to compensate for the variations, wherein said differential amplifier means has a first input terminal connected to said signal level adjusting means and a second input terminal connected to said reference means.

Claim 19

A motion picture camera operating system, comprising direct current motor means for controlling the number of frames per second of the camera, a direct current source for driving the motor, a tacho generator coupled to the motor for generating a speed indicating signal normally proportional to the speed of said motor but varying from the normal proportionality on the basis of temperature, motor speed control means responsive to said signal generating means, said motor speed control means including signal level adjusting means coupled to said signal generator means and having voltage attenuating means and a variable selector switch for selecting the attenuation of the voltage so as to change the number of frames per second of the camera, reference voltage supplying means connected to said direct current source for stabilizing a voltage supplied by the source and producing a reference voltage representing a predetermined motor speed, error signal producing means having a first input terminal connected to said reference means and a second input terminal connected to said selector switch for comparing the signal from said adjusting means and said reference means to produce an error signal depending upon the relation between the signal from said adjusting means and said reference means, waveform signal producing means for producing a signal having a waveform with a predetermined wave shape, modulating means coupled to said waveform-producing means and said error signal producing means for modulating the error signal on the basis of the signal with predetermined wave shape so as to produce a motor-driving pulse signal having rectangular pulses whose duration time varies in accordance with the level of said error signal, and switching means responsive to said modulating means for regulating the time during which the motor is driven in response to the duration of the pulse signals so as to vary the power applied to the motor, said reference means including a diode temperature compensating arrangement in parallel with said tacho generator and having a characteristic for cancelling variations of the speed indicating signal.

Claim 20

A motion picture camera operating system, comprising direct current motor means for controlling the number of frames per second of the camera, a direct current source for driving the motor, a tacho generator coupled to the motor for generating a speed indicating signal normally proportional to the speed of said motor but varying from the normal proportionality on the basis of temperature, motor speed control means responsive to said signal generating means, said motor speed control means including signal level adjusting means coupled to said signal generator means and having voltage attenuating means and a variable selector switch for selecting the attenuation of the voltage so as to change the number of frames per second of the camera, reference voltage supplying means connected to said direct current source for stabilizing a voltage supplied by the source and producing a reference voltage representing a predetermined motor speed, error signal producing means having a first input terminal connected to said reference means and a second input terminal connected to said selector switch for comparing the signal from said adjusting means and said reference means to produce an error signal depending upon the relation between the signal from said adjusting means and said reference means, waveform signal producing means for producing a signal having a waveform with a predetermined wave shape, modulating means coupled to said waveform-producing means and said error signal producing means for modulating the error signal on the basis of the signal with predetermined wave shape so as to produce a motor-driving pulse signal having rectangular pulses whose duration time varies in accordance with the level of said error signal, and switching means responsive to said modulating means for regulating the time during which the motor is driven in response to the duration of the pulse signals so as to vary the power applied to the motor, said reference means including a diode temperature compensating arrangement in parallel with said tacho generator and having a characteristic for cancelling variations of the speed indicating signal.

Claim 23

A speed control system for a direct current motor, comprising: (a) a DC tacho-generator means for generating a speed signal corresponding to the speed of the motor; (b) speed signal level adjusting means for producing an output corresponding to the speed signal, adjustment of the adjusting means varying the ratio of the output therefrom and the speed signal; (c) reference signal supplying means for producing a fixed reference signal, said reference signal supplying means including series-connected diodes for cancelling the variations of said DC tacho-generator due to temperature change; (d) differential amplifier means having a first input terminal connected to said adjusting means and a second input terminal connected to said reference signal supplying means, said differential amplifier means for comparing the output of said adjusting means with the reference signal of said reference signal supplying means and producing a control signal which is dependent on the output of said adjusting means and the reference signal of said reference signal supplying means; and (e) driving means responsive to the control signal from differential amplifier means for producing a motor driving current.

Claim 24

A speed control system for a direct current motor, comprising: (a) a DC tacho-generator means for generating a speed signal corresponding to the speed of the motor; (b) speed signal level adjusting means for producing an output corresponding to the speed signal, adjustment of the adjusting means varying the ratio of the output therefrom and the speed signal; (c) reference signal supplying means for producing a fixed reference signal, said reference signal supplying means including series-connected diodes for cancelling the variations of said DC tacho-generator due to temperature change; (d) differential amplifier means having a first input terminal connected to said adjusting means and a second input terminal connected to said reference signal supplying means, said differential amplifier means for comparing the output of said adjusting means with the reference signal of said reference signal supplying means and producing a control signal which is dependent on the output of said adjusting means and the reference signal of said reference signal supplying means; and (e) driving means responsive to the control signal from differential amplifier means for producing a motor driving current.

Claim 25

A motion picture camera operating system, comprising: (a) direct current motor means for controlling the number of frames per second of the camera; (b) a DC tacho-generator for generating a speed signal corresponding to the speed of the motor; (c) speed signal level adjusting means for producing an output signal corresponding to the speed signal, adjustment of the adjusting means varying the ratio of the output signal in response to a plurality of predetermined desired motor speeds; (d) reference signal supplying means for producing a fixed reference signal, said reference signal supplying means including series-connected diodes for cancelling the variations in the speed signal of said DC tacho-generator due to temperature change; (e) differential amplifier means having a first input terminal connected to said adjusting means and a second input terminal connected to said reference signal supplying means, said differential amplifier means for comparing the output of said adjusting means with the reference signal of said reference signal supplying means, and producing a control signal which is dependent on the output of said adjusting means and the reference signal of said reference signal supplying means; and (f) driving means responsive to the control signal from the differential amplifier means for producing a motor driving current.

Claim 26

A motion picture camera operating system, comprising: (a) direct current motor means for controlling the number of frames per second of the camera; (b) a DC tacho-generator for generating a speed signal corresponding to the speed of the motor; (c) speed signal level adjusting means for producing an output signal corresponding to the speed signal, adjustment of the adjusting means varying the ratio of the output signal in response to a plurality of predetermined desired motor speeds; (d) reference signal supplying means for producing a fixed reference signal, said reference signal supplying means including series-connected diodes for cancelling the variations in the speed signal of said DC tacho-generator due to temperature change; (e) differential amplifier means having a first input terminal connected to said adjusting means and a second input terminal connected to said reference signal supplying means, said differential amplifier means for comparing the output of said adjusting means with the reference signal of said reference signal supplying means, and producing a control signal which is dependent on the output of said adjusting means and the reference signal of said reference signal supplying means; and (f) driving means responsive to the control signal from the differential amplifier means for producing a motor driving current.