Load current control of pulse width modulated drive signal including calibration and correction coefficient

An apparatus for controlling a current of a load by modulating a pulse width of a drive pulse signal, comprising:

• control means for outputting a current instruction value to control said load;
• pulse width modulating means for inputting a current instruction value of said control means and for forming and outputting a pulse signal of a duty ratio according to said current instruction value;
• driving means for current driving said load by an output pulse signal of said pulse width modulating means;
• calibrating means, when executing a calibrating process, for outputting a reference current instruction value corresponding to a predetermined reference current of said load to said pulse width modulating means, for measuring a current of said load, and when said measurement current does not coincide with said reference current, for adjusting the current instruction value for said pulse width modulating section, for obtaining a current instruction value at which a measurement current that coincides with said reference current is derived, and for deciding a correction coefficient of the current instruction value from said measurement result;
• and
• correcting means for correcting said current instruction value which is outputted from said control means by said correction coefficient obtained by said calibrating means and for outputting to said pulse width modulating means.