Vibration generating apparatus

There is provided a vibration generating apparatus including: a housing having an internal space; a vibration member having both end portions thereof fixed to the housing; and a piezoelectric element installed on the vibration member, wherein the vibration member includes a first member having the piezoelectric element installed thereon and second members disposed at both end portions of the first member, the second members being formed of a material having a higher degree of tensile strength than the first member.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority and benefit of Korean Patent Application No. 10-2014-0027811 filed on Mar. 10, 2014, with the Korean Intellectual Property Office, the disclosure of which is incorporated in its entirety herein by reference.

BACKGROUND

The present disclosure relates to a vibration generating apparatus.

A vibration generating apparatus, converting electrical energy into mechanical vibrations using the principle of the generation of electromagnetic force, has been commonly been mounted in mobile phones, or the like, to be used for silently notifying a user of call reception by transferring vibrations thereto.

In addition, in accordance with the rapid expansion in the market for mobile devices such as mobile phones, and the like, mobile devices have been widely been implemented with increased functionality. In addition, the miniaturization of mobile devices has been demanded, along with improvements in the quality thereof.

In accordance with this trend, demand for development of a vibration generating apparatus having a novel structure capable of overcoming disadvantages of an existing vibration generating apparatus and significantly improving quality has increased.

Further, recently, mobile phones have largely been replaced by smartphones, and a touchscreen scheme has been adopted in the smart phone. Therefore, the use of a vibration generating apparatus has increased for the purpose of generating vibrations for user feedback at the time of a touch.

In addition, recently, a vibration generating apparatus using a piezoelectric element has been released onto the market. The vibration generating apparatus, which uses the principle of an inverse piezoelectric effect in generating displacement by applying voltage to the piezoelectric element, allows a mass body of a mover to move by the generated displacement to generate vibrational force.

In the vibration generating apparatus having the above-mentioned structure, a bandwidth of a frequency at which vibration force of a predetermined level or more may be obtained is wide, such that stable vibration characteristics may be implemented.

Meanwhile, the piezoelectric element is installed on a vibration member. Here, the piezoelectric element is bonded to the vibration member through a thermosetting adhesive. That is, the piezoelectric element and the vibration member are attached to each other through the thermosetting adhesive having relative high coupling force in order to prevent separation between the piezoelectric element and the vibration member. In addition, the thermosetting adhesive has a feature of being hardenable at high temperature.

Heat is applied in order to harden the thermosetting adhesive for attaching the piezoelectric element and the vibration member to each other. However, in this case, there may be a problem in that the vibration member may be deformed and bent due to a difference in a coefficient of thermal expansion between the piezoelectric element and the vibration member.

In order to solve this problem, the vibration member may be formed of a material having a low coefficient of thermal expansion (for example, a material containing 36 wt % or more of nickel). However, the vibration member is formed of the material having the low coefficient of thermal expansion as described above, such that the vibration member may be damaged at the time of vibrations.

Therefore, the development of a structure capable of preventing damage to the vibration member while maintaining coupling force between the piezoelectric element and the vibration member has been urgently demanded.

RELATED ART DOCUMENT

SUMMARY

An aspect of the present disclosure may provide a vibration generating apparatus capable of preventing damage to a vibration member.

According to an aspect of the present disclosure, a vibration generating apparatus may include: a housing having an internal space; a vibration member having both end portions thereof fixed to the housing; and a piezoelectric element installed on the vibration member, wherein the vibration member includes a first member having the piezoelectric element installed thereon and second members disposed at both end portions of the first member, the second members being formed of a material having a higher degree of tensile strength than the first member.

The piezoelectric element may be bonded to the first member through a thermosetting adhesive.

The first member may have stopper parts formed on both side surfaces thereof so as to support both side surfaces of the piezoelectric element.

The first member may have a lattice member formed on an upper surface thereof, the lattice member having a lattice shape.

The second member may have tensile strength 1.5 to 2 times larger than that of the first member.

The first member may have tensile strength of 36 to 835 N/mm2.

The housing may include a case having an internal space and a lower end portion that is open and a bracket attached to the lower end portion of the case, and the bracket may have support parts protruding therefrom in order to support lower surfaces of both end portions of the vibration member.

The vibration generating apparatus may further include a mass body part disposed above the vibration member to increase a vibration amount.

The mass body part may include a mass body case having an internal space and a mass body inserted into the mass body case, and the mass body case may be installed above the vibration member through an adhering member.

DETAILED DESCRIPTION

FIG. 1is a schematic cross-sectional view illustrating a vibration generating apparatus according to an exemplary embodiment of the present disclosure;FIG. 2is an exploded perspective view illustrating the vibration generating apparatus according to an exemplary embodiment of the present disclosure; andFIG. 3is a perspective view illustrating a vibration member included in the vibration generating apparatus according to an exemplary embodiment of the present disclosure.

Referring toFIGS. 1 through 3, a vibration generating apparatus100according to an exemplary embodiment of the present disclosure may include a housing110, a vibration member120, a piezoelectric element130, and a mass body part140by way of example.

The housing110may form an appearance of the vibration generating apparatus100and have an internal space so that the vibration member120, the piezoelectric element130, the mass body part140, and the like, may be accommodated therein. To this end, the housing110may include a case112having an internal space and having a box shape in which a lower end portion thereof is opened, and a bracket114attached to the lower end portion of the case112.

Meanwhile, the case112may have a rectangular parallelepiped shape, and the bracket114may have a plate shape. That is, the bracket114may be attached to the lower end portion of the case112to form the housing110.

Although the case in which the housing110has the rectangular parallelepiped shape has been described by way of example in the present exemplary embodiment, a shape of the housing110is not limited thereto, but may be variously changed.

In addition, the bracket114may have support parts114aformed in order to support both end portions of the vibration member120. The support parts114amay be formed by denting, and may have flat upper surfaces so as to stably support a lower surface of the vibration member120.

Meanwhile, the case112and the bracket114may be attached to each other by welding.

The vibration member120may have both end portions thereof fixed to the housing110. As an example, the vibration member120may be installed on the support parts114aof the bracket114. That is, the vibration member120may be installed so that lower surfaces of both end portions thereof are seated on the upper surfaces of the support parts114aof the bracket114, and the vibration member120and the bracket114may be bonded to each other by welding.

Although the case in which the vibration member120is fixed to the bracket114has been described by way of example in the present exemplary embodiment, the present disclosure is not limited thereto. That is, the vibration member120may also be fixed to the case112.

Meanwhile, the vibration member120may include a first member122having the piezoelectric element130installed thereon and second members124attached to both end portions of the first member122. Meanwhile, the second members124may be formed of a material having a higher degree of tensile strength than the first member122.

In addition, the first member122may have a length longer than that of the piezoelectric element130. That is, the first member122may be formed at the length longer than that of the piezoelectric element130in order to be bonded to the second members124. As an example, in the case in which the piezoelectric element130has a length of 17 mm, the first member122may have a length of at least 18.6 mm.

In addition, the first member122may be bonded to the piezoelectric element130through a thermosetting adhesive. Further, the first member122may have a lattice member122aformed on an upper surface thereof in order to increase coupling force between the first member122and the piezoelectric element130, wherein the lattice member122ahas a lattice shape. The lattice member122amay serve to increase a space in which the adhesive is accommodated to prevent the piezoelectric element130from being separated from the first member122at the time of deformation of the piezoelectric element130.

In addition, the first member122may have stopper parts122bformed on both side surfaces thereof so as to support both side surfaces of the piezoelectric element130at the time of assembling the piezoelectric element130. The stopper parts122bmay serve to prevent the adhesive applied to the first member122from being leaked to the outside simultaneously with guiding a position at which the piezoelectric element130is installed.

Meanwhile, the first member122may be formed of a material having a low coefficient of thermal expansion so as to be reduced from being deformed due to heat applied at the time of hardening the thermosetting adhesive. As an example, the first member122may be formed of an alloy containing approximately 36 wt % or more of nickel.

In addition, as an example, the first member122may have tensile strength of approximately 36 to 835 N/mm2.

Therefore, the first member122and the piezoelectric element130may be more firmly coupled to each other, and the deformation of the first member122due to the heat applied at the time of hardening the adhesive may be reduced.

The second members124may be coupled to both end portions of the first member122. Meanwhile, the second member124may have tensile strength 1.5 to 2 times larger than that of the first member122. To this end, the second member124may be formed of stainless steel (SUS). As an example, the second member124may have tensile strength of approximately 1200 N/mm2.

Meanwhile, in the case which the second member124has tensile strength 2 times or more larger than that of the first member122, a driving frequency may become high, such that a vibration amount may be decreased, and in the case in which the second member124has tensile strength 1.5 times or less larger than that of the first member122, damage may occur.

As described above, since the tensile strength of the second member124is larger than that of the first member122, the coupling force between the piezoelectric element130and the first member may be maintained, and the damage to the second member124at the time of vibrations may be prevented.

Meanwhile, the second member124and the first member122may be bonded to each other by at least one of a welding method and an adhering method.

The piezoelectric element130may be installed on the vibration member120and be deformed in the case in which power is applied thereto. That is, the piezoelectric element130may be installed on the lattice member122aof the first member122described above through the thermosetting adhesive. In addition, the piezoelectric element130may be installed so that both side surfaces thereof are supported by the stopper parts122bof the first member122.

Meanwhile, the piezoelectric element130may include at least one pair of external electrodes (not shown), which may include a positive (+) electrode and a negative (−) electrode. Therefore, when the power is applied to the piezoelectric element130, the piezoelectric element130may be deformed. As a result, a central portion of the vibration member120may vertically vibrate.

In addition, the piezoelectric element130may have a circuit board150connected thereto, wherein the circuit board150may be a flexible printed circuit board.

The mass body part140may be disposed above the vibration member120to serve to increase a vibration amount. Meanwhile, the mass body part140may be installed on an upper surface of the piezoelectric element130through an adhering member160.

In addition, the mass body part140may include a mass body case142having a box shape in which an upper portion thereof is opened and a mass body144installed in the mass body case142.

Further, the mass body case142and the piezoelectric element130may have the adhering member160installed therebetween. In addition, the adhering member160may be formed of an adhering tape.

Meanwhile, a damper member (not shown) may be installed on at least one of the mass body144and an inner surface of the case112in order to prevent generation of noise and damage to the case112due to a contact between the mass body144and the case112.

As described above, the second member124may be formed of the material having the a higher degree of tensile strength than the first member122on which the piezoelectric element130is installed, such that the damage to the second member124at the time of generation of the vibrations or external impact may be reduced.

Further, the first member122may be formed of the material having the low coefficient of thermal expansion, such that the coupling force between the first member122and the piezoelectric element130may be increased, and twisting of the first member122may be prevented.

That is, the first member122may be formed of the material having the low coefficient of thermal expansion, such that the deformation of the first member122due to the heat applied at the time of hardening the thermosetting adhesive may be reduced.

Hereinafter, a vibration generating apparatus according to another exemplary embodiment of the present disclosure will be described with reference to the accompanying drawings.

FIG. 4is a schematic cross-sectional view illustrating a vibration generating apparatus according to another embodiment of the present disclosure;FIG. 5is an exploded perspective view illustrating the vibration generating apparatus according to another exemplary embodiment of the present disclosure; andFIG. 6is a perspective view illustrating a vibration member included in the vibration generating apparatus according to another exemplary embodiment of the present disclosure.

Referring toFIGS. 4 through 6, a vibration generating apparatus200according to another exemplary embodiment of the present disclosure may include a housing210, a vibration member220, a piezoelectric element230, and a mass body part240by way of example.

The housing210may form an appearance of the vibration generating apparatus200and have an internal space so that the vibration member220, the piezoelectric element230, the mass body part240, and the like, may be accommodated therein.

To this end, the housing210may include a case212having an internal space and having a box shape in which a lower end portion thereof is opened, and a bracket214attached to the lower end portion of the case212.

Meanwhile, the case212may have a rectangular parallelepiped shape, and the bracket214may have a plate shape. That is, the bracket214may be attached to the lower end portion of the case212to form the housing210.

Although the case in which the housing210has the rectangular parallelepiped shape has been described by way of example in the present exemplary embodiment, a shape of the housing210is not limited thereto, but may be variously changed.

In addition, the case212may have a withdrawal groove212aformed in one end surface thereof in order to withdraw a circuit board250.

In addition, the bracket214may be provided with an installation part214bon which one side of the circuit board250withdrawn from the housing210to the outside is seated, wherein the installation part214bmay be disposed at an outer portion of the case212.

Meanwhile, the bracket214may have bonded parts214aformed at both end portions thereof and bent in order to install the vibration member220thereon. The bonded parts214amay be formed on both side surfaces of the bracket214, respectively, and may contact inner surfaces of the case212at the time of assembling the case212and the bracket214to each other.

In addition, the bonded part214amay have a length longer than that of a bent part224aof a vibration member220to be described below.

The vibration member220may have both end portions thereof fixed to the housing210. Meanwhile, the vibration member220may have a plate shape, and may have both end portions thereof fixed, such that the vibration member220vibrates vertically at the time of deformation of the piezoelectric element230.

Although the case in which the vibration member220is fixed to the bracket214has been described by way of example in the present exemplary embodiment, the present disclosure is not limited thereto. That is, the vibration member220may also be fixed to the case212.

Meanwhile, the vibration member220may include a first member222having the piezoelectric element230installed thereon and second members224attached to both end portions of the first member222. Meanwhile, the second members224may be formed of a material having a higher degree of tensile strength than the first member222.

In addition, the first member222may have a length longer than that of the piezoelectric element230. That is, the first member222may be formed at the length longer than that of the piezoelectric element230in order to be bonded to the second members224. As an example, in the case in which the piezoelectric element230has a length of 17 mm, the first member222may have a length of at least 18.6 mm.

In addition, the first member222may be bonded to the piezoelectric element230through a thermosetting adhesive. Further, the first member222may have a lattice member222aformed on an upper surface thereof in order to increase coupling force between the first member222and the piezoelectric element230, wherein the lattice member222ahas a lattice shape. The lattice member222amay serve to increase a space in which the adhesive is accommodated to prevent the piezoelectric element230from being separated from the first member222at the time of deformation of the piezoelectric element230.

In addition, the first member222may have stopper parts222bformed on both side surfaces thereof so as to support both side surfaces of the piezoelectric element230at the time of assembling the piezoelectric element230. The stopper parts222bmay serve to prevent the adhesive applied to the first member222from being leaked to the outside simultaneously with guiding a position at which the piezoelectric element230is installed.

Meanwhile, the first member222may be formed of a material having a low coefficient of thermal expansion so as to be reduced from being deformed due to heat applied at the time of hardening the thermosetting adhesive. As an example, the first member222may be formed of an alloy containing approximately 36 wt % or more of nickel.

In addition, as an example, the first member222may have tensile strength of approximately 36 to 835 N/mm2.

Therefore, the first member222and the piezoelectric element230may be more firmly coupled to each other, and the deformation of the first member222due to the heat applied at the time of hardening the adhesive may be reduced.

The second members224may be coupled to both end portions of the first member222. Meanwhile, the second member224may have tensile strength 1.5 to 2 times larger than that of the first member222. To this end, the second member224may be formed of stainless steel (SUS). As an example, the second member224may have tensile strength of approximately 1200 N/mm2.

Meanwhile, in the case which the second member224has tensile strength 2 times or more larger than that of the first member222, a driving frequency may become high, such that a vibration amount may be decreased, and in the case in which the second member224has tensile strength 1.5 times or less larger than that of the first member222, damage may occur.

As described above, since the second member224has the tensile strength 1.5 times to 2 times larger than that of the first member222, the coupling force between the piezoelectric element230and the first member222may be maintained, and the damage to the second member224at the time of vibrations may be prevented.

Meanwhile, the second member224and the first member222may be bonded to each other by at least one of a welding method and an adhering method.

In addition, the second members224may have bent parts224aformed at end portions thereof, wherein the bent parts224aare bonded to the bonded parts214aof the bracket214. In addition, the bent parts224amay be bonded to the bonded parts214aof the bracket214by at least one of a welding method and an adhering method.

In addition, outer surfaces of the bent parts224amay be bonded to inner surfaces of the bonded parts214a.

As described above, the vibration member220may be installed in the housing210by the bent parts224a, such that the vibration member220may be maintained in a state in which lower portions of both end portions thereof are opened.

The piezoelectric element230may be installed on one surface of the vibration member220. As an example, the piezoelectric element230may be installed on an upper surface of the vibration member220, that is, an upper surface of the first member222.

Meanwhile, the piezoelectric element230may be deformed in the case in which power is applied thereto, thereby serving to vibrate the vibration member220. To this end, the piezoelectric element230may include at least one pair of external electrodes (not shown), which may include a positive (+) electrode and a negative (−) electrode.

The mass body part240may be disposed above the vibration member220to serve to increase a vibration amount. Meanwhile, the mass body part240may be installed on an upper surface of the piezoelectric element230through an adhering member260.

In addition, the mass body part240may include a mass body case242having a box shape in which an upper portion thereof is opened and a mass body244installed in the mass body case242.

Further, the mass body case242and the piezoelectric element230may have the adhering member260installed therebetween. In addition, the adhering member260may be formed of an adhering tape.

Meanwhile, a damper member (not shown) may be installed on at least one of the mass body244and the inner surface of the case212in order to prevent generation of noise and damage to the case212due to a contact between the mass body244and the case212.

As described above, the second member224may be formed of the material having the a higher degree of tensile strength than the first member222on which the piezoelectric element230is installed, such that the damage to the second member224at the time of generation of the vibrations or external impact may be reduced.

Further, the first member222may be formed of the material having the low coefficient of thermal expansion, such that the coupling force between the first member222and the piezoelectric element230may be increased, and twisting of the first member222may be prevented.

That is, the first member222may be formed of the material having the low coefficient of thermal expansion, such that the deformation of the first member222due to the heat applied at the time of hardening the thermosetting adhesive may be reduced.

Further, since the vibration member220may be maintained in the state in which the lower portions of both end portions thereof are opened, space utilization may be increased.

As set forth above, according to exemplary embodiments of the present disclosure, the second member may be formed of the material having the a higher degree of tensile strength than the first member on which the piezoelectric element is installed, such that the damage to the second member at the time of the generation of the vibrations or the external impact may be reduced.

Further, the first member may be formed of the material having the low coefficient of thermal expansion, such that the coupling force between the first member and the piezoelectric element may be increased, and the twisting of the first member may be prevented.

That is, the first member may be formed of the material having the low coefficient of thermal expansion, such that the deformation of the first member due to the heat applied at the time of hardening the thermosetting adhesive may be reduced.