Electromagnetic actuator

An electromagnetic actuator comprising:

• (a) a magnet;
• (b) a pole piece mounted on the magnet;
• (c) a central yoke facing the pole piece and defining an inner gap therebetween;
• (d) a voice coil mounted within the inner gap;
• (e) an outer yoke facing the pole piece and defining an outer gap therebetween;
• (t) a vibration coil mounted within the outer gap;
• (g) a weight which vibrates responsive to excitation of the vibration coil;
• (h) a leaf spring supporting said weight;
• (i) a case enclosing (a) through (h);
• and (j) a diaphragm which vibrates responsive to excitation of the voice coil, wherein
• a first magnetic circuit is formed from the pole piece toward the center via the central yoke and the case with the inner gap therebetween;
• and
• a second magnetic circuit is formed from the pole piece toward the outer periphery via the outer yoke and the case with the outer gap therebetween.

An electromagnetic actuator comprising:

• (a) a magnet;
• (b) a pole piece mounted on the magnet;
• (c) a peripheral yoke facing the pole piece around the outer periphery of the pole piece and defining an outer gap therebetween;
• (d) a voice coil facing the pole piece and mounted within the outer gap;
• (e) a center yoke facing an inner peripheral surface of the pole piece and defining an inner gap therebetween;
• (f) a vibration coil facing the pole piece and mounted within the inner gap;
• (g) a weight which vibrates responsive to excitation of the vibration coil;
• (h) a leaf spring supporting the weight;
• (i) a case supporting the magnet and enclosing (a) through (h);
• and (j) a diaphragm which vibrates responsive to excitation of the voice coil, wherein
• a first magnetic circuit is formed from the pole piece toward the outer periphery via the peripheral yoke and the case with the outer gap sandwiched therebetween;
• and
• a second magnetic circuit is formed from the pole piece toward the center via the center yoke and the case with the inner gap sandwiched therebetween.