A motor control device includes a bridge circuit having semiconductor switching elements disposed in each arm thereof and being adapted for the connection of a motor between pairs of arms. The semiconductor switching elements are selectively rendered conductive to alternately drive the motor in forward and reverse directions, and certain ones of a semiconductor switching elements may be simultaneously rendered conductive to form a closed loop which short-circuits the motor and causes dynamic braking. The motor control device is capable of instantaneously stopping the rotation of the motor and is capable of rapidly reversing the motor's direction of rotation. The device is particularly useful in an automatic focusing apparatus or an automatic diaphragm setting apparatus in a camera.

Motor control device

A driver circuit for a transistor bridge is selectively controllable to produce four state operation of a DC motor. The driver circuit has two control inputs yielding four distinct input combinations, each combination producing a different state of motor operation. The states which may be selectively produced are (1) motor off or coasting, (2) motor on, counterclockwise rotation, (3) motor on, counterclockwise rotation and (4) motor off, dynamic braking.

Four state DC motor controller

A D-C MOTOR CONTROL SYSTEM COMPRISING A BRIDGE CIRCUIT, A REFERENCE VOLTAGE MEANS, AN AMPLIFYING MEANS, A POWER SOURCE AND A POWER CONTROL TRANSISTOR. THE BRIDGE CIRCUIT IS FORMED BY A D-C MOTOR AND THREE RESISTORS. THE TEMPERATURE COEFFICIENT OF THE ELECTRIC RESISTANCE OF THE FIRST RESISTOR IS ESSENTIALLY SIMILAR TO THAT OF THE ARMATURE WINDING OF THE D-C MOTOR AND THE COEFFICIENTS OF THE SEC- OND AND THIRD RESISTORS ARE ESSENTIALLY SIMILAR TO EACH OTHER. THE AMPLIFYING MEANS IS CONNECTED TO SAID BRIDGE CIRCUIT AND CONTROLS THE CONDUCTIVITY OF THE POWER CONTROL TRANSISTOR WHICH MAKES IT POSSIBLE FOR THE D-C MOTOR TO ROTATE AT A SUBSTANTIALLY CONSTANT SPEED.

D.c. motor control system

In an apparatus for driving a stepping motor in a micro step manner by a PWM control signal generated based on a sense voltage, including a sense resistor for generating the sense voltage, a driving current path including the sense resistor and the stepping motor is provided and is operated so that a driving current flows through the stepping motor, when the PWM control signal is activated. A regenerative current path including the sense resistor and is provided the stepping motor and is operated so that a regenerative current flows through the stepping motor, when the PWM control signal is not activated. A resistance of the regenerative current path is larger than a resistance of the driving current path.

Stepping motor driving apparatus having small time constant regenerative current path

A motor brake device comprises a plurality of transistors for shunting a circuit loop through which a back electromotive force current caused by an inertia rotation of the motor flows, in which some of these transistors are operated as an inversed transistor (a transistor operated in a state where the collector and the emitter are interchanged with each other). The brake current for the motor flows through the collector-emitter paths of the transistor and the reversed transistor, each of which exhibits a small voltage drop. Therefore, the electromagnetic brake may effectively be applied to the motor even at a considerably low back electromotive force of the motor.

Michael T Krivak

Papers

On-off direct current motor control network with dynamic braking