Load drive control system

A load drive control system comprising:

• instruction means for selectively producing forward and reverse drive instruction signals for starting the driving of a controlled load in forward and reverse directions respectively;
• signal holding switching means for holding a forward or reverse signal corresponding to the forward or reverse drive instruction signal from said instruction means;
• said instruction means comprising an automatically-restoring switch which switches by receiving an actuation force to generate one of said instruction signals and restores when the actuation force is released to stop the generation of the one instruction signal;
• reversible motor means for driving said load in either forward or reverse direction;
• means responsive to said signal holding switching means for controlling electric cirrent supplied from a power supply to said motor means;
• current detecting means for detecting the magnitude of the current supplied to said motor means;
• and upper and lower limit detecting means responsive to said current detecting means for releasing the holding action of said holding switching means when the motor supplied current becomes higher or lower than an upper or lower limit respectively;
• and wherein said signal holding switching means includes first switching means for defining a forward drive circuit for driving said motor means in the forward direction, second switching means for enabling and disabling said first switching means respectively in response to said forward drive instruction signal and said limit detection signal, third switching means for defining a reverse drive circuit for driving said motor means in the reverse direction, and fourth switching means for enabling and disabling said third switching means respectively in response to said reverse drive instruction signal and said limit detection signal.

A load drive control system comprising:

• a reversible motor for driving a mechanical load in either forward or reverse direction depending upon the direction of current flowing between its two brushes, the load current through said reversible motor varying according to resistance of said mechanical load;
• instruction means for generating an instruction for selecting the direction of driving of said reversible motor;
• first and second electric switch means for selectively effecting electric connection of the respective brushes of said reversible motor to the opposite terminals of a DC power supply;
• a current detecting resistor means for producing a voltage drop according to the load current caused through said reversible motor when a complementary connection of the brushes of said reversible motor to the opposite terminals of the DC power supply is made by said first and second electric switch means;
• voltage responsive means responsive to the voltage drop across said resistor means and producing a detection signal when said voltage drop is lower than a first predetermined level and also when said voltage drop is higher than a second predetermined level higher than said first predetermined level;
• and
• control means responsive to said instruction means and also to said voltage responsive means and functioning to achieve the electric connection of said first and second electric means in response to said instruction from said instruction means and holding said electric connection during the absence of said detection signal from said voltage sensitive means, said instructions means comprising an automatically-restoring switch which switches by receiving an actuation force to generate said instruction signal and restores when the actuation force is released to stop the generation of said instruction signal.