Technique for controlling current limiter of motor

A method of controlling a current limiter of a motor for protecting said motor by limiting an amount of current supplied to said motor according to a current limiter control signal and controlling a driving force of said motor, said method comprising the steps of:

• (A) setting a duty cycle value D0 of a pulse width modulation signal, which is said current limiter control signal, for each mode;
• (B) determining whether a present execution mode corresponds to a mode for altering a limit amount of current of said current limiter;
• (C) detecting a rotational frequency fc of said motor;
• and
• (D) if it is determined in step (B) that the present execution mode is said mode for altering said limit amount of current, altering the duty cycle value D0 set in step (A) according to the rotational frequency fc.

A method of controlling a current limiter of a motor for protecting said motor by limiting an amount of electric current supplied to said motor and controlling a driving force of said motor, comprising the steps of:

• detecting a rotational frequency of said motor;
• generating a current limiter control signal corresponding to the rotational frequency detected in said detecting step;
• and
• limiting the amount of current supplied to said motor in accordance with said current limiter control signal;
• wherein said generating step comprises generating a pulse width modulation signal having pulses of different duty cycle according to said detected rotational frequency in accordance with a plurality of execution modes;
• and
• said method further comprising the steps of determining whether a present execution mode corresponds to one of said plurality of execution modes in which a limit amount of current of said current limiter is alterable, and altering a duty cycle for said one of said plurality of execution modes when it is determined, in said determining step, that the present execution mode does correspond to said one of said plurality of execution modes in which the limit amount of current of said current limiter is alterable.

An apparatus for controlling a current limiter of a motor for protecting said motor by limiting an amount of current supplied to said motor according to a current limiter control signal and controlling a driving force of said motor, said apparatus comprising:

• (A) setting means for setting a duty cycle value D0 of a pulse width modulation signal, which is said current limiter control signal for each mode;
• (B) determining means for determining whether a present execution mode corresponds to a mode for altering a limit amount of current of said current limiter;
• (C) detecting means for detecting a rotational frequency fc of said motor;
• and
• (D) altering means for altering the duty cycle value D0 set by the setting means according to the rotational frequency fc if the determining means determines in step (B) that the present execution mode is said mode for altering said limit amount of current.

In a video recording device, an apparatus for controlling a motor of said device and protecting said motor by limiting an amount of electric current supplied to said motor and controlling a driving force of said motor, said apparatus comprising:

• frequency generator means associated with said motor for generating a signal corresponding in frequency to a rotational frequency of said motor;
• first circuit means responsive to said signal generated by said frequency generator means for generating a motor driving signal;
• second circuit means connected to said frequency generator means and responsive to said signal generated by said frequency generator means for generating a frequency detection signal;
• limiter controller means connected to said second circuit means and responsive to said frequency detection signal generated by said second circuit means for generating a current limiter control signal corresponding to the rotational frequency of said motor;
• and
• current limiter means connected to said first circuit means and to said limiter controller means for limiting the amount of electric current supplied to said motor in accordance with said current limiter control signal generated by said limiter controller means and said motor driving signal generated by said first circuit means.