Abstract: A motor driving device includes a brake mode control section for starting, when a brake instruction for a motor, braking of the motor in a reverse brake mode and then switching the reverse brake mode to a short brake mode; a cycle start detection section for receiving a rotation signal and detecting a start of a cycle of the rotation signal for each cycle; and a counter for performing, when the start of the cycle of the rotation signal is detected by the cycle start detection section, a count operation from an initial value. In the motor driving device, the brake mode control section detects that a value of the counter exceeds a threshold and performs switching from the reverse brake mode to the short brake mode with a delay from the detection.

Abstract: A control device and a method of stopping the spindle motor or an optical disc system. The control device primarily includes an optical disc control chip, a motor driving circuit and a spindle motor. The optical disc control chip generates and delivers a spindle motor control signal to the motor driving circuit for driving the spindle motor into rotation. During a first period, the spindle motor control signal level is controlled to produce the largest reversing torque permitted by the spindle motor for braking purpose. During a second period, the spindle motor control signal level decreases gradually to approach to a lock level that is smaller than that for actuating the spindle motor, so that the reversing torque is also decreasing gradually.

Abstract: The present invention relates to a braking system for a DC motor. The braking system includes a current control element placed across the terminals of the DC motor to regulate the magnitude of the electric current generated by the motor when the motor is in a braking mode of operation. In the most preferred embodiment, the current control element includes a semiconductor switch, such as a transistor, that is repeatedly pulsed on and off to act as a controlled short circuit across the armature of the motor. The rotational energy is dissipated as heat by the inherent resistance of the motor windings that may be augmented by an external resistor, if desired. Another possibility is to use a current control element that includes a variable load designed to dissipate the rotational energy in the form of heat. The impedance of the load element is gradually reduced as the speed of the motor is reduced to maintain the rate of energy dissipation near the peak allowable value for the structure of the DC motor.

Abstract: A universal motor (18) for a power tool (10) has a stator assembly (22) and an armature (24). The stator assembly includes a plurality of interconnected field windings (28-34) to which current is supplied to run the motor. The armature has a commutator (36) including brushes (40a, 40b) for circulating current through the armature. To quickly and safely brake the motor, without excessively damaging the brushes, a switch (16) is interposed between an AC power source for the motor and the armature. In one embodiment, the switch shorts the armature during braking. In this embodiment, the switch includes sets (56, 58, 60) of electrical contacts by which the inner field windings (28, 30) are connected in series with the outer filed windings (32, 34); and the field windings are series connected with the armature.

Abstract: A motor control circuit, in which the motor is driven to rotate by a driving current according to a torque control signal and the motor rotation is stopped by generating a torque on the motor in the reversing direction when a stop signal for stopping the motor is received, further being provided with a level inverting circuit disposed between a torque control signal generating circuit and a drive circuit for inverting the level of the torque control signal with respect to a predetermined reference level, a level inverted torque control signal by the level inverting circuit is outputted to the drive circuit when the stop signal is received, and further provided with a reference signal generating circuit generating a reference signal corresponding to a reference rotational speed of the motor as well as generating another reference signal corresponding to a rotational speed lower than that of the reference rotational speed when the stop signal is received.