A conventional inverse electromotive force eliminating device for a motor utilizes a transistor element for eliminating an inverse electromotive force. With the conventional system a first transistor is required for driving the transistor element. Consequently, the circuit becomes complicated. Several problems arise due to the increase complexity. For example, significant time and a considerable amount of money are necessary to repair damage to the circuit.
A conventional example, shown in FIG. 1, corresponds to a motor control device for a magnetic disc system disclosed in Japanese Laid Open Patent Publication No. Hei-2-290174. The device includes a spindle motor 11 for rotating a recording medium, motor driving means 12 for driving said spindle motor 11, detecting means 13 for detecting an error in the power supply fed to said motor driving means 12 by power supply means 14, switch means 15 for short-circuiting between phases for driving said spindle motor 11 or between said coil and ground in an ON state, and switch control means 16 for setting said switch means to an ON state when a power supply error is detected by said detecting means 13, so that current generated at spindle motor 11 by an inverse electromotive force is eliminated. However, concerns have developed that an error in operation results because current generated by the inverse electromotive force generated at the spindle motor during a power supply error is eliminated. In particular, a problem has arisen where the motor suddenly stops rotating.
USPTO Backgrounds
USPTO Backgrounds