WO2016111601A1

WO2016111601A1 - Apparatus for generating electrical energy

Info

Publication number: WO2016111601A1
Application number: PCT/KR2016/000235
Authority: WO
Inventors: 이상구; 권명주
Original assignee: (주)아이블포토닉스
Priority date: 2015-01-09
Filing date: 2016-01-11
Publication date: 2016-07-14

Abstract

According to the present invention, provided is an apparatus for generating electrical energy, comprising: a piezoelectric body having at least two surfaces; and an elastic body which is located on at least one surface of the surfaces of the piezoelectric body and delivers displacement to the piezoelectric body, wherein if external force is applied to the elastic body and the elastic body is pressed in one direction and deformed, the force of the elastic body which presses the piezoelectric body is converted into vibrations in which the pressing force repeatedly increases and decreases, and then vibration displacement is transmitted to the piezoelectric body. The apparatus according to the present invention converts the force of a low vibration frequency applied to the piezoelectric body into a high vibration frequency through a simple principle, thereby generating far more electrical energy than existing apparatuses.

Description

Electrical energy generator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrical energy generating apparatus, and more particularly, to an electrical energy generating apparatus which can obtain more electrical energy by pressing a piezoelectric body.

Acquisition of electrical energy can be accomplished in a variety of ways. Existing electricity production methods include conventional thermal power generation and nuclear power generation. For example, electricity generation methods in the renewable energy field include wind, hydro, tidal, geothermal, solar, and solar power generation. . This type of power generation is largely on a large scale and can be used in everyday life by being supplied through an electrical grid.

On the other hand, some of the various electronic devices used in everyday life is configured to use the electrical energy through the battery. However, the materials required for battery production are harmful to the human body, which causes many problems in the production and disposal of the battery, and even while the battery is in use, recharging or replacing the battery after the battery is discharged is relatively cumbersome. have.

In consideration of the above problems of the prior art, energy harvesting has recently been recognized as a very important technical field, and active research is being conducted. In particular, according to the trend that the use of electronic devices in a mobile environment is an important part of daily life, the technology of harvesting mechanical energy and converting / storing it into electrical energy is a device / material / It needs a structure. In particular, there is a need to overcome the limitations of the electronic device structure according to the battery volume, and also to solve the problem of charging the discharged battery and the replacement of the battery to be discarded in another way.

Methods of generating electricity using mechanical movement include (1) coil / magnet-based electromagnetic induction generation, (2) electrostatic generation using variable capacitors, and (3) piezoelectric generation. The method of (1) is very widely used as in the case of general motors or turbines, but it is difficult to make the size / weight of the system small, and the method of (2) is a cycle of charge / mechanical deformation / discharge / mechanical deformation (ie, reversal). It is complex because the design must be made with the circuit to go through. (3) In the case of power generation using piezoelectric material, mechanical force is applied to the piezoelectric material to induce deformation of size, and the structure of the piezoelectric material is very simple and miniaturized by generating electricity. There is an advantage in that there is an active research on this.

Specifically, the piezoelectric material is a material that generates electricity when the size is changed by an external force. In particular, due to the nature of piezoelectricity, the size deformation of a material must occur largely, quickly and frequently to generate a large amount of electricity. For this reason, a piezoelectric power generator of a cantilever structure has been mainly used in an environment having high frequency mechanical vibration.

However, in the case of the piezoelectric generator of the cantilever structure, it can be operated efficiently by generating a large and fast displacement only when the surrounding mechanical vibration is similar to the inherent resonance frequency of the cantilever, and when the frequency is not matched, it generates a large electricity. There is difficulty. In addition, when the force acting is large enough but appears at a low frequency, for example, when a person walks or pushes a button, the piezoelectric generator of a general cantilever structure cannot generate a large amount of electricity.

The present invention has been made to solve the above problems, it is an object of the present invention to provide a device that can generate more electrical energy by pressing the piezoelectric body.

Another object of the present invention is to provide an electric energy generating device for vibrating a piezoelectric body using a spring.

Another object of the present invention is to provide an electric energy generating device capable of obtaining the required electric energy by simply pressing the user without using a battery.

According to the invention,

Piezoelectric bodies having at least two surfaces;

An elastic body positioned on at least one surface of the surface of the piezoelectric body and transmitting a displacement to the piezoelectric body; And

The other surface corresponding to the surface on which the elastic body is located is provided with an electric energy generating device having a means for accommodating the displacement of the piezoelectric body.

According to one embodiment, the elastic body is changed in the form of vibration repeating the increase and decrease the force applied to the elastic body when the deformation is pressed in one direction by the application of an external force, so that the displacement vibrating on the piezoelectric body Electrical energy generating device is provided.

According to one embodiment, further comprising a pressing means for transmitting a force to the elastic body,

The piezoelectric material includes a piezoelectric material layer having a first electrode provided on a first surface and a second electrode provided on an opposing second surface.

The piezoelectric body may be provided on one or both surfaces of the substrate.

Preferably, the elastic body includes N unit elastic bodies (where N is two or more), and the number of vibrations may be N times or less.

In addition, the unit elastic body is in relation to the instantaneous spring constant k defined by k = F / x when x is the displacement of the unit elastic body by the force (F) applied by the pressing means,

When displacements x ₁ , x ₂ and x ₃ are x ₁ <x ₂ <x ₃

Instantaneous spring constant k ₁ , when displacement 0 <x <x ₁

When the displacement x ₁ <x <x ₂ time the spring constant k _2, and

When the displacement x ₂ <x <x ₃ the instantaneous spring constant k ₃ is

It may have an elastic characteristic that satisfies the condition k ₁ > 0, k ₂ ≤ 0, k ₃ > 0.

According to an embodiment, the substrate may serve to support the piezoelectric material, but may have a material and a structure that do not substantially limit the piezoelectric displacement due to the displacement transmitted from the elastic body.

In addition, the other surface of the surface of the piezoelectric body corresponding to the surface where the elastic body is located is provided with a space that can accommodate the displacement of the piezoelectric body,

It may be provided with a protrusion that can cause the twisting movement of the piezoelectric body selectively between the space or the piezoelectric body and the elastic body.

According to one embodiment, the piezoelectric body may be made of a piezoelectric single crystal or a piezoelectric material.

According to one embodiment, the piezoelectric body may have a piezoelectric characteristic of d33, d15 or d31 mode.

In addition, further comprising a pressing means for transmitting a force to the elastic body,

The piezoelectric body may be formed of a piezoelectric material layer having a first electrode provided on a first surface and a second electrode provided on an opposing second surface.

According to another embodiment, the substrate may serve as the elastic body without a separate elastic body, and the substrate may have a structure for transferring the cantilevered displacement generated by the pressing means to the piezoelectric body.

According to another embodiment, using the above-described electric energy generating device as a unit generator, a plurality of unit generators may have a structure in a series or parallel structure.

According to a preferred embodiment, the unit elastic body is a snap dome having an upper surface and a lower surface, the snap dome may be stacked so that the upper surface is in contact with each other, the lower surface is in contact with the lower surface.

According to the present invention, even if a mechanical force is directly applied to the piezoelectric body, a problem of the prior art in which a small amount of electric energy or no electric energy can be obtained due to the low frequency is solved by the present invention. That is, when a force is applied in the form of a person pushing a button, the rate of rise of the voltage is so low that the electric energy generated from the piezoelectric body is consumed as a leakage current, and the magnitude of displacement of the piezoelectric body is solved. The problem is limited and the increase in voltage is simply limited in one direction.

In the present invention, there is an advantage that the electric energy can be obtained by adopting a new structure using a piezoelectric body and a spring so that the user can generate a sufficient electric energy only by pressing a button mechanically. Further, in the present invention, after the applied force is stored in a spring having a non-linear force-displacement characteristic, the piezoelectric element can be vibrated with a larger displacement by adopting a structure that transmits the force to the piezoelectric element for a short time. Also, the current due to the vibration of the piezoelectric body can be obtained as an alternating current component, and can generate much larger electrical energy than the electrical energy of the piezoelectric body due to simple pressurization.

1 and 2 are graphs schematically showing the relationship between the displacement of the elastic body and the force applied to the elastic body.

3 to 5 are schematic exploded perspective views of an electric energy generating device according to various embodiments of the present disclosure.

6 is a schematic cross-sectional view of an electrical energy generating device according to another embodiment of the present invention.

7A and 7B schematically illustrate a state in which an electric energy generating device is mounted on an experimental device in order to measure a voltage of electric energy generated in the electric energy generating device.

FIG. 8 is a graph of voltage over time showing test results of the electric energy generating device shown in FIGS. 7A and 7B.

9A and 9B are photographs showing a state and an experimental process of applying the apparatus according to the present invention to a mobile phone home button.

FIG. 10 shows the results of experiments using the apparatus of FIGS. 9A and 9B.

11 is a photograph showing an example of a snap dome.

12 schematically illustrates the snap dome cross-sectional shape in which deformation occurs when a pressing force is applied.

13 is a cross-sectional view schematically showing the shape of the snap dome stack.

14 is a force-strain graph when the snap dome stack is pressed.

15 schematically illustrates a configuration of an electric energy generating device according to an embodiment of the present invention.

16 schematically illustrates a method for measuring power generation of a snap dome stack according to an embodiment of the present invention.

Figure 17 shows the actual manufacturing process of the snap dome stack according to an embodiment of the present invention.

18A and 18B show an operation test process of a piezoelectric generator manufactured according to one embodiment of the present invention.

19 shows the results of a push experiment according to the number of snap domes of a snap dome stack according to an embodiment of the present invention.

20 is a graph showing the energy generation form of a piezoelectric generator according to an embodiment of the present invention.

Hereinafter, with reference to the embodiments of the present invention shown in the accompanying drawings will be described in more detail. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, or substitutes included in the spirit and scope of the present invention.

Due to the nature of piezoelectric materials, the efficiency of converting mechanical energy into electrical energy is high only at high frequencies (usually above 100 Hz), and rapidly at low frequencies (usually below 1 Hz). The development of energy harvesting technology is very important because of the large number of low frequency vibrations in our daily lives. In other words, the technology of applying pressure to the piezoelectric material by converting a low frequency force into a high frequency is the most essential part in the development of the piezoelectric generator.

In the present invention, in order to solve the problem of lowering the efficiency of piezoelectric generators against low frequency forces, it is necessary to repeatedly stack and press elements (unit elastic bodies) in which snap-through-buckling occurs, such as a snap dome. It is characterized by the fact that the force repeatedly vibrates during deformation.

In addition, the present invention has the advantage that a sufficient electrical energy can be obtained by adopting a new structure that can generate a lot more electrical energy than the existing by converting the force of the low frequency applied to the piezoelectric material to a high frequency, such a feature May be used to power sensor nodes in wireless sensor networks or the Internet of Things (IoT), which have recently gained increasing interest. Alternatively, it is applied to a shoe or insole that generates electricity while walking, and may be used immediately after being temporarily stored in a battery or as a power source for driving a smart shoe or a smart insole. In this case, it is possible to replace the existing battery or to replace the power supply of wired and wireless charging method. In addition, if applied to the military boots walking is expected to be able to recharge or directly supply the electrical energy required by the soldiers.

It can be used to power sensor nodes in wireless sensor networks or the Internet of Things (IoT), which have recently gained increasing interest. Alternatively, it is applied to a shoe or insole that generates electricity while walking, and may be used immediately after being temporarily stored in a battery or as a power source for driving a smart shoe or a smart insole. In this case, it is possible to replace the existing battery or to replace the power supply of wired and wireless charging method. In addition, if applied to the military boots walking is expected to be able to recharge or directly supply the electrical energy needed by the soldiers.

In the present invention, the external force provided by the user is accumulated in an elastic body such as a spring, and the electrical force is produced by releasing the accumulated force for a relatively short time to vibrate the piezoelectric body.

Specifically, the electric energy generating device according to the present invention includes a piezoelectric body having at least two surfaces; And

An elastic body positioned on at least one surface of the surface of the piezoelectric body and transmitting a displacement to the piezoelectric body,

The elastic body is an electrical energy generating device that when the deformation is pressed in one direction by the application of an external force, the force applied to the elastic body is changed in the form of a vibration repeating the increase and decrease, so that the displacement vibrating on the piezoelectric body to occur. Is provided.

In this case, the elastic body preferably comprises N unit elastic bodies (where N is two or more), and the number of vibrations may be N times or less.

The unit elastic bodies may be stacked such that displacement of each unit elastic body sequentially causes displacement of other unit elastic bodies.

The elastic body is like a spring, for example a buckling spring, in which the relationship of force to displacement is nonlinear. After the elastic body accumulates the applied external force as a displacement, the elastic body can transfer the accumulated external force to the piezoelectric body for a short time when the specific displacement is exceeded. The piezoelectric element vibrates by displacement for a short time when the external force is applied and when the external force is removed, respectively, and the vibration of the piezoelectric element is sufficient to generate electrical energy.

In the present invention, when the elastic body or unit elastic body is x, the displacement of the elastic body due to the force (F) applied by the pressing means in relation to the instantaneous spring constant k defined by k = ΔF / Δx Have the same characteristics.

When displacements x ₁ , x ₂ and x ₃ are x ₁ <x ₂ <x ₃

Instantaneous spring constant k ₁ , when displacement 0 <x <x ₁

When the displacement x ₁ <x <x ₂ time the spring constant k _2, and

The conditions k ₁ > 0, k ₂ ≤ 0, and k ₃ > 0 are satisfied.

1 and 2 illustrate the elastic properties as described above.

When the displacement of the unit when pressing the elastic body by the pressing means that depth x is 0 and the initial depth of the snap-may be called the depth of time lead to buckling (snap-through-bucking) x 1 - through. The maximum displacement of the unit elastic body, that is, the depth when it touches the floor, may be referred to as x ₃ .

In other words, when pressed by the pressurizing means as shown in Figure 1, the force should initially increase to deepen the depth, but when reaching a certain depth (x ₁ ), the depth will naturally increase even if the force does not increase (between x ₁ and x ₂ ) Again, increasing force results in a deeper area (between x ₂ and x ₃ ). Wherein x ₂ and x ₃ is defined as the depth having a power and the power of the same size in x ₁ in sayi x ₂ ', and increasing the pressing force applied to the pressing means, measuring the depth of the depth x ₁ as in the second When it reaches, it will be pressed down to depth x ₂ 'without increasing the force.

In this case, snap-through-buckling means that in the general mechanical force (F) -strain curve, the deformation increases with the external force. Force indicates that there is a decreasing interval. For example, when a button is pressed on a TV remote control, a telephone keypad, a computer keyboard, or a mouse, a sudden press is applied when a certain amount of force is applied. Physically, when F is plotted on the Y-axis and strain on the X-axis, it represents a section where dF / d (strain) <0 exists.

Examples of the elastic body having such elastic properties include, but are not limited to, a buckling spring, a snap-through buckle spring, a disk spring, a dome spring, and the like. In some cases, the substrate itself may serve as an elastic body. The substrate may serve as the elastic body without a separate elastic body, and the substrate may have a structure for transferring the cantilevered displacement generated by the pressing means to the piezoelectric body.

According to a preferred embodiment it is possible to use a snap dome as the elastic body. Snapdom is generally used as an ultra-thin push switch (see http://www.inovan.de/, http://www.snaptron.com/), one example of which is shown in FIG. Usually the edges touch the floor but the middle part is slightly floating, so if you press the middle part, before the center part touches the floor, the pressing force of the center is suddenly transmitted to the edge and it turns off completely. Snap-through-buckling.

Hereinafter, with reference to an embodiment shown in the accompanying drawings the present invention will be described in more detail.

An electric energy generating device according to the present invention comprises: a piezoelectric body having at least two surfaces; An elastic body positioned on at least one surface of the surface of the piezoelectric body and transmitting a displacement to the piezoelectric body; And means for accommodating displacement of the piezoelectric body on the other surface corresponding to the surface on which the elastic body is located.

Displacement of the elastic body transferred to the piezoelectric body may be generated by pressing means for transmitting a force to the elastic body.

3 to 5 are schematic exploded perspective views of an electric energy generating apparatus having a piezoelectric body according to various embodiments of the present disclosure. Since this is only an example of the present invention, the present invention is not limited to this structure, and various modifications are possible within the scope of the present invention.

Specifically, FIGS. 3 to 5 illustrate a case where a disc spring is used as an elastic body, but is not limited thereto, and the elastic body according to the present invention may be used without limitation as long as the elastic body according to the present invention has the elasticity as described above with reference to FIGS. 1 and 2. Can be.

3 to 5, the electric energy generating device is provided on a substrate 10, a first electrode 12a disposed on the substrate 10 and provided on a first surface, and on an opposing second surface. A piezoelectric body 11 having a second electrode 12b formed therein, pressing means 15 disposed on the piezoelectric body 11 so as to pressurize the piezoelectric body 11, the piezoelectric body 11 and the pressing It is provided with a spring 13 arranged between the means 15. The other side of the substrate on which the piezoelectric body is located is provided with means (16, 17, 18) for receiving the displacement of the piezoelectric body transmitted by the displacement of the spring.

As a means for accommodating the displacement transmitted by the elastic body, Figure 3 is an elastic sheet 16 such as rubber or foam foam, Figure 4 is a ring-shaped structure 17 can provide a space, Figure 5 is a piezoelectric or Two or more columnar structures 18 are shown to form a space by separating the substrate on which the piezoelectric body is formed from other structures at predetermined intervals. In addition, various modifications may be possible.

The piezoelectric body 11 is supported on the first surface of the substrate 10. As shown, the piezoelectric body may be formed only on one surface of the substrate, but the present invention is not limited thereto, and the piezoelectric body may be formed on both surfaces of the substrate.

The substrate 10 preferably serves to support the piezoelectric material, but has a material and a structure that do not substantially limit the piezoelectric displacement due to the displacement transmitted from the elastic body. For example, a material such as a copper plate or an aluminum plate that is thin and stirs is preferable.

According to a preferred embodiment, the insulating

layer

10a, 10b may be formed on the first surface and the opposite second surface of the substrate 10, respectively.

The piezoelectric body 11 may be made of a piezoelectric single crystal or a piezoelectric material. For example, it may be made of a piezoelectric single crystal or piezoceramic, or a piezoelectric polymer containing or not containing lead. Piezoelectric single crystals have a structure in which fine particles having a predetermined structure are regularly arranged.

The piezoelectric body may have a piezoelectric characteristic of d33, d15, or d31 mode.

Specifically, for example, the piezoelectric single crystal may be a solid solution single crystal of magnesium niobate (PMN), which is a relaxor, and lead titanate (PT), which is a piezoelectric body. When the single crystal is used as the piezoelectric material in the acceleration sensor, the piezoelectric distortion is three times or more, compared with the conventional piezoelectric material, the electromechanical coupling coefficient is large, and excellent piezoelectric properties are exhibited. As an alternative, piezoelectric ceramics, such as lead zirconate titanate (PZT) ceramics, which are examples of known piezoelectric materials, can be used.

The first electrode 12a is formed on the first surface of the piezoelectric element 11, and the second electrode 12b is formed on the opposing second surface. The

electrodes

12a and 12b are connected to terminals of a circuit board (not shown) through wires not shown. When the piezoelectric body 11 vibrates as described later, electrical energy is generated, and the electrical energy generated from the piezoelectric body 11 can be supplied to an electronic device on a circuit board through wiring.

The disk spring 13 exemplified as an elastic body has a shape of a part or a dome as a whole, the bottom part is opened and the top part is formed with an opening. In other examples not shown in the figures, the opening may be closed. The elastic body is not limited to the shape as shown in FIGS. 3 to 5, and may be used without limitation as long as it has elasticity as described above with reference to FIGS. 1 and 2.

The relationship between the displacement of the elastic body and the force can cause the piezoelectric body disposed adjacent to the elastic body to vibrate. In other words, the displacement of the elastic body can produce the displacement of the piezoelectric body.

When the force is removed after pressing the elastic enough to enter the depth (x ₁ ) where snap-through-buckling occurs, the inverse region (x ₁ -x ₂ ), where the spring constant is negative and the spring constant is positive Only after passing through the region (x ₂ -x ₃ ) can it be restored to its original position. At this time, as shown in FIG. 1, the magnitude of the force at the moment of removing the force at the end of the inversion region is smaller than the magnitude of the maximum force in the proportional region. Therefore, assuming that the elastic body is pressed, the force is in the opposite direction in the proportional region to push it, so that the piezoelectric element disposed under the elastic body can generate a force to move in the form of free vibration.

Therefore, in the present invention, the spring constant uses an elastic body in which k may have a negative (-) region.

Referring again to FIGS. 3 to 5, a button is arranged as the pressing means 15 capable of pressing the spring 13 on top of the spring 13. The button can have any shape that allows the user to press the spring 13. At the bottom of the pressing means 15, such as a button, a protrusion can be formed which can be inserted into an opening formed in the upper portion of the spring 13. An insulating layer 14 is formed on the bottom surface of the button to provide electrical insulation between the spring 13 and the button.

In the electric energy generating device configured as shown in FIGS. 3 to 5, the user can deform the spring 13 by pressing the pressing means 15 such as a button. When the force for pressing the spring 13 is removed, the spring 13 is restored to its original state through the relationship of displacement and force as described with reference to FIGS. 1 and 2, which pressurizes and restores the spring 13. The piezoelectric body 11 is vibrated in the process. The vibration of the piezoelectric body 11 generates electrical energy, and the generated electrical energy can be supplied through a wire connected to the

electrodes

12a and 12b.

3 to 5 illustrate an example in which an elastic body is positioned between the pressing means and the piezoelectric body, but is not limited thereto. The piezoelectric body may be designed to be positioned between the pressing means and the elastic body. In any case, if the displacement of the elastic body is transferred to the piezoelectric body so that the piezoelectric body can have a displacement, that is, it can vibrate, the electric energy generating device according to the present invention can be implemented.

According to the embodiment illustrated in FIG. 6, the substrate may serve as the elastic body without a separate elastic body, and the substrate may have a structure for transferring the cantilevered displacement generated by the pressing means to the piezoelectric body.

Specifically, FIG. 6 is a schematic cross-sectional view of an apparatus for transmitting cantilevered displacement to a piezoelectric body. The protrusions 26 are formed on the pillars 24 of the button 15, and the piezoelectric body 21 is formed on one surface or both surfaces of the substrate 23. The substrate 23 may be a circular substrate having an opening formed in the center thereof, or may have a structure in which a plurality of rectangular substrates in the form of a spring board are symmetrically disposed about the pillar of the button.

In the structure shown in FIG. 6, when the button 25 is pressed, the protrusion 26 presses the inner end of the substrate 23 downward and presses the button 25 further to lower the protrusion 26 to raise the substrate 23. The piezoelectric body 21 formed on the substrate 23 vibrates while being bounced in the direction. In this case, the substrate 23 simultaneously serves as an elastic body.

Before the projection 26 contacts the cantilever substrate 23 only the spring constant of the bottom spring 27 (ie k ₄ ) is applied, and when the projection 26 contacts the substrate 23, the spring constant becomes large ( In other words, k ₅ ), the substrate 23 is still bent and bounced back to the initial spring constant k ₄ . In other words, when the spring bounces back and forth, a transition from k ₅ (a sum of the cantilever substrate spring effect and the bottom spring effect caused by the protrusion) to a small k ₄ occurs, and at this time, the pressurizing means is completely turned off.

On the other hand, according to another embodiment, by using the electric energy generating device according to the present invention as a unit generator, it is possible to have a structure in which a plurality of unit generators are assembled in series or parallel structure.

7A and 7B schematically illustrate a state in which an electric energy generating device is mounted on an experimental device for measuring a voltage of electric energy generated in the electric energy generating device. FIG. 7A is an electrical energy generator having an elastic body according to the present invention, while FIG. 7B is an electrical energy generator without an elastic body.

Referring to FIG. 7A, the metal plate 30 is supported by the support 40, and the piezoelectric element 31, the elastic body 33, and the pressing means 35 are disposed on the metal plate 30. The metal plate 30 is in contact with the support 40 through the insulating

layers

30a and 30b, and the electrode 32a is formed on the upper surface of the piezoelectric body 31. An insulating layer is disposed between the pressing means 35 and the elastic body 33.

The piezoelectric body 31 was configured as a rectangular parallelepiped having a dimension of approximately 1 cm x 0.5 cm x 0.1 mm as a whole, and the diameter of the bottom face of the spring 33 was approximately 0.6 cm. Referring to FIG. 7B, it is the same as the electric energy generating device shown in FIG. 7A, except that the elastic body 33 is not provided. That is, the metal plate 31 is supported by the support 40, and the piezoelectric element 31 and the pressing means 35 are disposed on the metal plate 31.

FIG. 8 is a graph of voltage over time showing experimental results of the electric energy generating apparatus shown in FIGS. 7A and 7B.

Referring to the drawings, the voltage generated in the electric energy generating device with the elastic body 33 is indicated at the top of FIG. 8, while the voltage generated in the electric energy generating device without the elastic body 33 is shown in the lower part of FIG. 8. It is.

As can be seen in FIG. 8, when the elastic member 33 is provided, a voltage having an absolute value of at least 3 volts is generated as the pressing means 35 is pressed, and the voltage is applied when a force for pressing the spring is applied. And one time in the form of free vibration once the pressing force is removed. In contrast, in the absence of the elastic body 33, the magnitude of the absolute value of the voltage is less than 0.5 volts. In FIG. 8, the wavy shape of about 0.2-0.3 volts at 60 Hz is a signal coming out as background noise due to the microscopic vibration naturally occurring when the power is applied to the experimental device, and has no relation to the signal coming out from the pressing device.

Figures 9a and 9b shows the process and results of the experiment by mounting the electric energy generating device according to the present invention to the mobile phone home button. FIG. 10 is a result of measuring voltage generation by repeatedly pressing the home button in the experimental apparatus of FIGS. 9A and 9B, and it can be seen that a voltage of about 8V is consistently generated even after 100 times and 1000 times.

Examples of the elastic body having elastic properties according to the present invention include, but are not limited to, a buckling spring, a snap-through-buckling spring, a disk spring, a dome spring, and the like.

According to a preferred embodiment, a snap dome can be used as the elastic body. Snapdom is generally used as an ultra-thin push switch (see http://www.inovan.de/, http://www.snaptron.com/), one example of which is shown in FIG. Usually the edges touch the floor but the middle part is slightly floating, so if you press the middle part, before the center part touches the floor, the pressing force of the center is suddenly transmitted to the edge and it turns off completely. Snap-through-buckling.

12 is a schematic representation of the shape of the snapdom cross section in which deformation occurs when a pressing force is applied. If you measure strain while increasing the force, you can see that the strain suddenly jumps at the same force when you go to the area where snap-through-buckling occurs.

In the electric energy generating device according to the present invention, it is preferable that the unit elastic bodies are stacked such that displacement of each unit elastic body sequentially causes displacement of adjacent unit elastic bodies.

FIG. 13 shows a stack of snapdom stacks stacked upside down in the opposite direction. At this time, the first snap dome is first placed, the second snap dome is inverted in the opposite direction to the first snap dome, stacked on the first snap dome, and the third snap dome is inverted in the opposite direction to the second snap dome, ie, the first snap dome. Stacked on the second snap dome in the same direction as the dome. As such, adjacent snapdoms may be repeatedly stacked in an opposite direction to form a stack of N snapdoms. This places the top of one snap dome and the top of the other slab in contact with each other and the opposite side, i.e., the bottom, with the bottom of the next (other) snap dome, as shown in FIG. And are repeatedly arranged to face each other in opposite directions.

14 shows the force-strain graph that appears when the snap dome stack is pressed. As the force increases, the snapdoms in the snapdom stack are initially deformed as a whole, at which point one snapdom causes snap-through-buckling and the rest of the snapdomes are in series. It will cause a snap-through-buckling. In other words, the force is changed in the form of vibration without pressing the additional force while continuing to press. As shown in Fig. 14, the deformation continues, but the force repeats decreasing / increasing in the form of vibration. When the number of snapdoms used in the snapdom stack is N, the number of vibrations shown in the force-strain graph is up to N times. have.

15 schematically illustrates a configuration of an electric energy generating device according to an embodiment of the present invention using a snap dome stack. Since this is only an example of the present invention, the present invention is not limited to this structure, and various modifications are possible within the scope of the present invention.

As shown in FIG. 15, it is preferable that another surface of the surface of the piezoelectric body corresponding to the surface on which the elastic body is located is provided with a space for accommodating the displacement of the piezoelectric body.

Also, although not shown, more electrical energy can be generated by providing protrusions that can cause twisting of the piezoelectric body selectively between the space or the piezoelectric body and the elastic body.

In the present invention, the piezoelectric body may be made of a piezoelectric single crystal or a piezoelectric material. For example, it may be made of a piezoelectric single crystal or piezoceramic, or a piezoelectric polymer containing or not containing lead. Piezoelectric single crystals have a structure in which fine particles having a predetermined structure are regularly arranged.

As shown in FIG. 15, the snap dome stack acts like a spring, initially pushing the outer push switch, and pressing the push switch with an external force causes the snap dome stack to contract. When the pressing force is removed again, it is returned to the original state by the elastic restoring force of each snap dome.

FIG. 16 shows a method for measuring power generation when snap-through-buckling of the snap dome stack shown in FIG. 15 is actually applied. Power generated in the piezoelectric body may be stored in the capacitor via a rectifier circuit or directly connected to a rechargeable battery instead of the capacitor.

Figure 17 shows the actual fabrication process for actually testing the performance of the snap dome stack. A, B, C, D is a frame manufacturing drawing for installing a snap dome stack, A is the upper frame, B is the pressing portion, C is the bottom frame, D represents the bottom frame. The upper frame (A) is to hold the movement path of the pressing portion when the pressing portion presses the snap dome stack and secures a space in which the pressing portion moves. Pressing portion (B) is a pressing portion by pressing the snap dome stack is in contact with the upper portion. When pressed, it moves down and directly pushes the snap dome stack. The lower frame C has an inner space according to the shape of the snapdom stack so that it can be stably pressed when the snapdom stack is pressed. The bottom frame D is a position where the piezoelectric material to which the piezoelectric material is attached is located, and has a little space at the bottom so that the piezoelectric material can be lowered slightly when pressed. E is actually a snap dome stack frame. F shows the shape when the snapdom stack removed from E is assembled. G represents the piezoelectric body mounted under the snapdom stack. H shows the snap dome stack mounted inside the frame.

18A and 18B correspond to the operation test of the piezoelectric generator manufactured as in FIG. 17 before and after pressing of FIG. 15, respectively.

19 schematically shows the results of a push experiment according to the number of snap domes of a snap dome stack. Pressed at 2 mm / s and stopped at 1500 gram-force, changing the number of snapdoms to 1, 3, 5, 7, and 9 shows the depth of force-force change graph for each structure.

20 is a graph showing the energy generation form of the piezoelectric generator according to one embodiment of the present invention (number of snap domes). The wires electrically connected to both sides of the piezoelectric generator are connected to the capacitor through the bridge diode rectifier circuit, and the voltage applied to the capacitor is measured and calculated as stored energy.

As described above, in the present invention, by converting a high frequency through a simple principle, the force of the low frequency applied to the piezoelectric body can generate much more electric energy than before.

The electrical energy generating device according to the present invention can be applied in various ways. For example, it may be used as a non-powered remote controller, a non-powered keyboard, a non-powered door lock, or a personal keypad. When the electric energy generating device is applied to a non-powered remote controller, even if a separate battery is not provided, electric energy is generated only by a user pressing a button on the remote controller, and an infrared signal may be generated using the electric energy. In addition, even in a wireless keyboard that is not wired to the computer, the user may generate electrical energy only by typing on the keyboard, and transmit the keyboard signal to the computer body using the electrical energy.

In the present invention, there is an advantage that a sufficient electrical energy can be obtained by adopting a new structure that can generate a lot more electrical energy than the existing by converting a low frequency force applied to the piezoelectric material to a high frequency. It can be used to power sensor nodes in a wireless sensor network or Internet of Things (IoT) of growing interest. Alternatively, it is applied to a shoe or insole that generates electricity while walking, and may be used immediately after being temporarily stored in a battery or as a power source for driving a smart shoe or a smart insole.

Claims

Piezoelectric bodies having at least two surfaces;

An elastic body positioned on at least one surface of the surface of the piezoelectric body and transmitting a displacement to the piezoelectric body; And

And an other surface corresponding to the surface on which the elastic body is located is provided with means for accommodating displacement of the piezoelectric body.
The method of claim 1,

The elastic body is an electrical energy generating device that when the deformation is pressed in one direction by the application of an external force, the force applied to the elastic body is changed in the form of a vibration repeating the increase and decrease, so that the displacement vibrating on the piezoelectric body to occur. .
The method of claim 1,

Further provided with a pressing means for transmitting a force to the elastic body,

The piezoelectric material includes a piezoelectric material layer having a first electrode provided on a first surface and a second electrode provided on an opposing second surface.

The piezoelectric body is an electrical energy generating device that is provided on one side or both sides of the substrate.
The method of claim 1,

The elastic body includes N unit elastic bodies (wherein N is 2 or more), and the number of vibrations is an electric energy generating device N times or less.
The method of claim 4, wherein

The unit elastic body is an electrical energy generating device is laminated so that the displacement of each unit elastic body causes the displacement of the other unit elastic body.
The method of claim 4, wherein

The unit elastic body is related to the instantaneous spring constant k defined by k = ΔF / Δx when x is a displacement of the unit elastic body due to the force F applied by the pressing means.

When displacements x 1 , x 2 and x 3 are x 1 <x 2 <x 3

Instantaneous spring constant k 1 , when displacement 0 <x <x 1

When the displacement x 1 <x <x 2 time the spring constant k 2, and

When the displacement x 2 <x <x 3 the instantaneous spring constant k 3 is

An electric energy generating device having elastic properties satisfying the conditions of k 1 > 0, k 2 ≤ 0, k 3 > 0.
The method of claim 3,

The substrate serves to support the piezoelectric material, but has a material and structure that does not substantially limit the displacement of the piezoelectric due to the displacement transmitted from the elastic body.
The method of claim 1,

The other surface of the surface of the piezoelectric body corresponding to the surface on which the elastic body is located is provided with a space for accommodating the displacement of the piezoelectric device.
The method of claim 8,

And a protrusion capable of causing a warping movement of the piezoelectric body selectively between the space or between the piezoelectric body and the elastic body.
The method of claim 1,

The piezoelectric material is an electric energy generating device comprising a piezoelectric single crystal or a piezoelectric material.
The method of claim 1,

And the piezoelectric member has a piezoelectric characteristic of d33, d15 or d31 mode.
The method of claim 3,

The substrate serves as the elastic body without a separate elastic body,

And said substrate has a structure for transferring a cantilevered displacement generated by said pressing means to a piezoelectric body.
The method of claim 1,

Further provided with a pressing means for transmitting a force to the elastic body,

And the piezoelectric body comprises a piezoelectric material layer having a first electrode provided on a first surface and a second electrode provided on an opposing second surface.
The method of claim 1,

Electrical energy generating device wherein the elastic body is a snap dome.
An electric energy generating device comprising a plurality of unit power generating bodies assembled in a series or parallel structure using the electric energy generating device of any one of claims 1 to 14 as a unit power generating body.