Motor driving apparatus

A motor driving apparatus comprising:

• a rotor including a magnet, the magnet being cylindrical shaped and divided, in a peripheral direction, into sections each with an outer periphery, each section having a different polarity from adjacent sections;
• a first yoke including a first magnetic portion, the first yoke being opposed to the outer periphery of the magnet;
• a first coil configured to, if energized, excite the first magnetic portion;
• a second yoke including a second magnetic portion, the second yoke being opposed to the outer periphery of the magnet at a position displaced by an electrical angel of 90 degrees relative to the first magnetic portion;
• a second coil configured to, if energized, excite the second magnetic portion;
• a detecting portion including a first detection element, a second detection element, a third detection element, and a fourth detection element, each detection element being configured to detect a rotation position of the rotor;
• and
• a controller configured to switch a pole excited by the first magnetic portion and the second magnetic portion by switching an energization direction of the first coil and the second coil based on an output of the detecting portion,
• wherein the first detection element is arranged at a position where an advance angle amount from a position at which an electrical advance angle from an excitation switching timing of each first magnetic portion is 0 degree is smaller than a delay angle amount from a position at which an electrical advance angle from an excitation switching timing of each first magnetic portion is 90 degrees if the rotor is caused to rotate in a first rotation direction and if a pole excited by the first magnetic portion is switched based on an output of the first detection element,
• wherein the second detection element is arranged at a position where an advance angle amount from a position at which an electrical advance angle from an excitation switching timing of each second magnetic portion is 0 degree is smaller than a delay angle amount from a position at which an electrical advance angle from an excitation switching timing of each second magnetic portion is 90 degrees if the rotor is caused to rotate in the first rotation direction and if a pole excited by the second magnetic portion is switched based on an output of the second detection element,
• wherein the third detection element is arranged at a position where an advance angle amount from a position at which an electrical advance angle from an excitation switching timing of each first magnetic portion is 0 degree is larger than a delay angle amount from a position at which an electrical advance angle from an excitation switching timing of each first magnetic portion is 90 degrees if the rotor is caused to rotate in the first rotation direction and if a pole excited by the first magnetic portion is switched based on an output of the third detection element, and
• wherein the fourth detection element is arranged at a position where an advance angle amount from a position at which an electrical advance angle from an excitation switching timing of each second magnetic portion is 0 degree is larger than a delay angle amount from a position at which an electrical advance angle from an excitation switching timing of each second magnetic portion is 90 degrees if the rotor is caused to rotate in the first rotation direction and if a pole excited by the second magnetic portion is switched based on an output of the fourth detection element.