Acoustic vibration generating element
View Patent ↗In an acoustic vibration generating element, a piezoelectric bimorph element or unimorph element is covered with a covering member of a flexible material at least on two surfaces perpendicular to a thickness direction. The covering member may be provided with a plurality of V-shaped grooves so as to improve a generated vibrating force. Alternatively, the covering member may be provided with an air chamber in the vicinity of a surface of one side so as to prevent sound leakage. Further, the covering member and an earhook may be integrally formed by the flexible material so as to achieve a light-weight acoustic vibration generating element suitable for a bone conduction speaker.
1. A bone conduction acoustic vibration generating element comprising:
a piezoelectric bimorph or unimorph element; and
a covering member made of a flexible material and attached to at least two surfaces perpendicular to a thickness direction of the piezoelectric bimorph or unimorph element,
wherein a ratio of flexural modulus to a weight per unit length of the bone conduction acoustic vibration generating element is smaller than a ratio of flexural modulus to a weight per unit length of the piezoelectric bimorph or unimorph element only.
2. The bone conduction acoustic vibration generating element according to claim 1 , wherein the covering member covers a whole of the piezoelectric bimorph or unimorph element.
3. The bone conduction acoustic vibration generating element according to claim 2 , wherein the piezoelectric bimorph or unimorph element is a piezoelectric bimorph element which has a laminated structure comprising piezoelectric ceramics sheets and internal electrodes.
4. The bone conduction acoustic vibration generating element according to claim 3 , further comprising an earhook portion made of the flexible material and integrally formed with the covering member.
5. The bone conduction acoustic vibration generating element according claim 2 , further comprising an earhook portion made of the flexible material and integrally formed with the covering member.
6. The bone conduction acoustic vibration generating element according to claim 2 , wherein the bone conduction acoustic vibration generating element radiates acoustic energy to a human body through at least a part of the flexible material.
7. The bone conduction acoustic vibration generating element according to claim 1 , wherein the bone conduction acoustic vibration generating element radiates acoustic energy to a human body through at least a part of the flexible material.
8. The bone conduction acoustic vibration generating element according to claim 7 , wherein the piezoelectric bimorph or unimorph element is a piezoelectric bimorph element which has a laminated structure comprising piezoelectric ceramics sheets and internal electrodes.
9. The bone conduction acoustic vibration generating element according to claim 8 , further comprising an earhook portion made of the flexible material and integrally formed with the covering member.
10. The bone conduction acoustic vibration generating element according claim 7 , further comprising an earhook portion made of the flexible material and integrally formed with the covering member.
11. The bone conduction acoustic vibration generating element according to claim 1 , wherein a plurality of grooves are formed on a surface of the covering member.
12. The bone conduction acoustic vibration generating element according to claim 11 , wherein the piezoelectric bimorph or unimorph element is a piezoelectric bimorph element which has a laminated structure comprising piezoelectric ceramics sheets and internal electrodes.
13. The bone conduction acoustic vibration generating element according to claim 12 , further comprising an earhook portion made of the flexible material and integrally formed with the covering member.
14. The bone conduction acoustic vibration generating element according claim 11 , further comprising an earhook portion made of the flexible material and integrally formed with the covering member.
15. The bone conduction acoustic vibration generating element according to claim 1 , wherein the covering member is provided with an air chamber formed on one side thereof.
16. The bone conduction acoustic vibration generating element according to claim 15 , wherein the piezoelectric bimorph or unimorph element is a piezoelectric bimorph element which has a laminated structure comprising piezoelectric ceramics sheets and internal electrodes.
17. The bone conduction acoustic vibration generating element according to claim 16 , further comprising an earhook portion made of the flexible material and integrally formed with the covering member.
18. The bone conduction acoustic vibration generating element according claim 15 , further comprising an earhook portion made of the flexible material and integrally formed with the covering member.
19. The bone conduction acoustic vibration generating element according to claim 1 , wherein the piezoelectric bimorph or unimorph element is a piezoelectric bimorph element which has a laminated structure comprising piezoelectric ceramics sheets and internal electrodes.
20. The bone conduction acoustic vibration generating element according to claim 19 , further comprising an earhook portion made of the flexible material and integrally formed with the covering member.
21. The bone conduction acoustic vibration generating element according claim 1 , further comprising an earhook portion made of the flexible material and integrally formed with the covering member.