Bone conduction speaker
A bone conduction speaker is provided. The bone conduction speaker includes: a housing forming an exterior; a stator including a pole piece fitted to a bottom of the housing and a voice coil arranged to an outer circumference of the pole piece; a vibrator including a permanent magnet mounted concentrically with the pole piece and voice coil, with an air gap from the pole piece, a weight attached to the permanent magnet to increase a vibration force, and a yoke attached to the permanent magnet and weight; a flexible printed circuit board mounted on the bottom of the housing, part of which extends out of the housing, and configured to transmit a signal to the voice coil; and a bone conduction pad attached to an outer surface of the housing. The vibration of the vibrator is transmitted to a bone of a user through the housing and bone conduction pad.
1. A bone conduction speaker, comprising:
a housing forming an exterior;
a stator comprising a pole piece fitted to a bottom of the housing and a voice coil arranged to an outer circumference of the pole piece;
a vibrator comprising a permanent magnet mounted concentrically with the pole piece and the voice coil, with an air gap from the pole piece and a weight attached to the permanent magnet to increase a vibration force, and a yoke attached to the permanent magnet and the weight;
a flexible printed circuit board (F-PCB) mounted on the bottom of the housing, part of which extends out of the housing, and configured to transmit a signal to the voice coil;
an external structure enclosing the exterior of the housing, one side of which is open; and
a bone conduction pad attached to an outer surface of the housing and enclosed with a sidewall of the external structure,
wherein vibration of the vibrator is transmitted to a bone of a user through the housing and the bone conduction pad.
2. The bone conduction speaker of claim 1 , wherein a magnetic fluid is applied around the pole piece and the permanent magnet, so that an amplitude of the vibrator is limited in a low-frequency resonance condition.
3. The bone conduction speaker of claim 1 , further comprising a piezoelectric element attached to the housing and configured to transmit a high-frequency signal.
4. The bone conduction speaker of claim 3 , wherein the F-PCB comprises a chip resistor in a circuit configured to transmit a signal to the piezoelectric element to prevent overcurrent at high frequencies.
5. The bone conduction speaker of claim 1 , wherein the bone conduction pad is bonded to the housing.
6. The bone conduction speaker of claim 1 , wherein the bone conduction pad is attached by pressure to one side of the external structure.
7. The bone conduction speaker of claim 1 , further comprising a sound leakage prevention structure fitted between the external structure and the housing.
8. The bone conduction speaker of claim 1 , wherein sound emission holes are formed in the side of the external structure so that sound is produced by air conduction.
9. The bone conduction speaker of claim 1 , wherein the housing is circular shaped.
10. The bone conduction speaker of claim 1 , wherein the housing is polygonal shaped.