Vibration generating device

1. A vibration generating device comprising:

a housing having an internal space;

a vibration member of which one end is fixedly attached to the housing;

a piezoelectric element installed on the vibration member; and

a mass body fixedly attached to the vibration member,

wherein the vibration member includes:

an installation part on which the piezoelectric element is installed; and

an extension part extended from at least one side surface of the installation part,

wherein the extension part of the vibration member includes:

a first extension part extended from one side surface of the installation part; and

a second extension part extended from the other side surface of the installation part,

wherein the first extension part includes:

a first width direction extension plate extended from one side surface of the installation part; and

a first length direction extension plate extended from a distal end of the first width direction extension plate in a length direction of the installation part,

wherein the second extension part includes:

a second width direction extension plate extended from the other side surface of the installation part; and

a second length direction extension plate extended from a distal end of the second width direction extension plate to be parallel with respect to the first length direction extension plate,

wherein the mass body is bonded to the first and second length direction extension plates to be fixedly attached to the vibration members and

wherein a maximum displacement portion of the vibration member is changed depending on a vibration mode.

2. The vibration generating device of claim 1 , wherein the first and second length direction extension plates are shaped to have step portions.

3. The vibration generating device of claim 1 , wherein the mass body is bonded to the first and second length direction extension plates via an adhesive member.

4. The vibration generating device of claim 1 , wherein a support protrusion for supporting side surfaces of the piezoelectric element is provided on the installation part.

5. The vibration generating device of claim 1 , wherein the housing includes an installation member to which the installation part is bonded.

6. The vibration generating device of claim 1 , wherein the housing includes:

a case in which an internal space is provided and of which a lower end is open; and

a bracket which is coupled to the lower end of the case.

7. The vibration generating device of claim 1 , wherein;

the vibration member is deformed in first and second vibration modes, and

a difference between resonance frequencies in the first and second vibration modes is 50 Hz or more.

8. The vibration generating device of claim 7 , wherein the resonance frequencies in the first and second vibration modes are in a range of 50 Hz to 400 Hz.

9. A vibration generating device comprising;

a housing having an internal space:

a vibration member of which one end is fixedly attached to the housing;

a piezoelectric element installed on the vibration member; and

a mass body fixedly attached to the vibration member,

wherein the vibration member includes:

an installation part on which the piezoelectric element is installed; and

an extension part extended from at least one side surface of the installation part,

wherein the extension part of the vibration member includes:

a first extension part extended from one side surface of the installation part; and

a second extension part extended from the other side surface of the installation part,

wherein the first extension part includes:

a first width direction extension plate extended from one side surface of the installation part; and

a first length direction extension plate extended from a distal end of the first width direction extension plate in a length direction of the installation part,

wherein the second extension part includes:

a second width direction extension plate extended from the other side surface of the installation part; and

a second length direction extension plate extended from a distal end of the second width direction extension plate to be parallel with respect to the first length direction extension plate,

wherein a maximum displacement portion of the vibration member is changed depending on a vibration mode, and

wherein an insertion groove into which the installation part is inserted is provided in a bottom surface of the mass body, and the bottom surface of the mass body is, inclined upwardly from a free end of the installation part toward a fixed end thereof so as to prevent a contact with the installation part.

10. A vibration generating device comprising:

a housing having an internal space;

a vibration member of which one end is fixedly attached to the housing;

a piezoelectric element installed on the vibration member; and

a mass body fixedly attached to the vibration member,

wherein the vibration member includes an installation part on which the piezoelectric element is installed, and an extension part extended from at least one side surface of the installation part,

wherein a maximum displacement portion of the vibration member is changed depending on a vibration mode,

wherein the extension part includes a width direction extension plate extended from one side surface of the installation part, and a length direction extension plate extended from a distal end of the width direction extension plate in a length direction of the installation part, and

wherein the length direction extension plate is shaped to have a step portion, and the mass body is bonded to the length direction extension plate.