KR20160086040A - Electric Energy Generating Device - Google Patents

Abstract

According to the present invention, provided is an electric energy generating device, comprising: a piezoelectric body having at least two surfaces; an elastic body placed on at least one of the surfaces of the piezoelectric body and transmitting displacement to the piezoelectric body; and a means placed on a surface, which is a different and corresponds to a surface where the elastic body is disposed, in order to accommodate the displacement of the piezoelectric body. The purpose of the present invention is to provide an electric energy generating device including a piezoelectric body.

Description

TECHNICAL FIELD [0001] The present invention relates to an electric energy generating device,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electric energy generating device, and more particularly, to an electric energy generating device capable of obtaining electric energy by vibrating a piezoelectric body using a spring.

 Acquisition of electrical energy can be done in a variety of ways. Existing electric production methods include conventional thermal power generation and nuclear power generation. Examples of electric power generation methods in the renewable energy field include wind power, hydroelectric power, tidal power, geothermal power, solar heat, and solar power generation . This type of development is mostly large-scale and electricity can be used in everyday life by supplying electricity through an electrical grid.

On the other hand, some of the various electronic devices used in daily life are configured to use electric energy through a battery. However, since the substances required for battery production are harmful to the human body, it causes many problems in the production and disposal of the battery, and the operation of charging the battery or replacing the battery after the discharge of the battery even during use of the battery is relatively cumbersome have.

Considering the problems of the prior art as described above, energy harvesting has recently been recognized as a very important technology field, and active research is underway. In particular, the use of electronic devices in the mobile environment is an important part of everyday life. Therefore, the technology of harvesting and converting mechanical energy into electric energy is an effective means of converting energy / Structure and so on. Particularly, there is a need to overcome the restriction of the electronic device structure according to the battery volume, and to solve the charging problem of the discharged battery and the replacement problem of the battery to be discarded by other methods.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electric energy generating device having a piezoelectric body.

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

It is another object of the present invention to provide an electric energy generating device which can obtain electric energy required only by a simple operation of a user without using a battery.

According to the present invention,

A piezoelectric body having at least two surfaces;

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

And the other surface corresponding to the surface on which the elastic body is located is provided with means capable of accommodating the displacement of the piezoelectric body.

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

The piezoelectric body is composed of a piezoelectric material layer having a first electrode provided on a first surface and a second electrode provided on a second surface,

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

According to one embodiment, the elastic body has a displacement x ₁ , x (x), in relation to an instantaneous spring constant k defined by k = ΔF / Δx when the displacement of the elastic body by the force F applied by the pressing means is x ₂ and x ₃ are x ₁ < x ₂ < x ₃

When the displacement 0 <x <x ₁ , the instantaneous spring constant k 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

k ₁ > 0, k _{2 & lt} ; 0, and k ₃ &gt; 0.

According to an embodiment, the substrate may have a material and a structure that supports the piezoelectric body and does not substantially limit displacement of the piezoelectric body due to displacement transmitted from the elastic body.

According to an 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 the d33, d15 or d31 mode.

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 transmitting the cantilever displacement generated by the pressing means to the piezoelectric body.

According to another embodiment, the above-described electric energy generating device may be a unit electric generator, and a plurality of unit generators may be aggregated into a series or parallel structure.

According to the present invention, the problem of the prior art in which electric energy can not be obtained even when a mechanical force is directly applied to the piezoelectric body is solved by the present invention. That is, when a force is applied in the same manner as a pressing operation of a button, the rising speed of the voltage is too low to solve the problem that the electric energy generated from the piezoelectric body is consumed by the leakage current or the like. And the problem that the increase of the voltage is simply limited in one direction is solved.

The present invention has an advantage that electric energy can be obtained by adopting a new structure using a piezoelectric body and a spring so that a user can mechanically generate enough electric energy only by pressing a button. Further, in the present invention, the piezoelectric body can be made to vibrate at a larger displacement by adopting a structure in which the applied force is stored in a spring having a nonlinear force-displacement characteristic and then the force is transmitted to the piezoelectric body for a short time. Also, the current due to the vibration of the piezoelectric body can be obtained as an AC component, and can generate electric energy much larger than the electric energy of the piezoelectric body due to the simple pressing.

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 apparatus according to various embodiments of the present invention.
6 is a schematic cross-sectional view of an electric energy generating apparatus according to another embodiment of the present invention.
FIGS. 7A and 7B schematically show a state in which an electric energy generating apparatus is mounted on an experimental apparatus for measuring a voltage of electric energy generated in the electric energy generating apparatus. FIG.
8 is a graph of voltage with time showing test results of the electric energy generating apparatus shown in Figs. 7A and 7B.
FIGS. 9A and 9B are photographs showing a state in which the device according to the present invention is applied to a mobile phone home button and an experimental procedure.
Fig. 10 shows the results of experiments using the apparatus of Figs. 9a and 9b.

In the present invention, an external force provided by a user is stored in an elastic body such as a spring, and the electric power is generated by oscillating the piezoelectric body by discharging the accumulated force for a relatively short time.

The elastic body is a spring, for example, a buckling spring in which a relation of force to displacement is nonlinearly formed. The elastic body can transmit the accumulated external force to the piezoelectric body for a short period of time after the applied external force is accumulated at the displacement and then the specific displacement is exceeded. The piezoelectric body vibrates by causing a displacement for a short time when an external force is applied and when the external force is removed, and the vibration of such a piezoelectric body is made to a sufficient degree to generate electric energy.

In the present invention, the elastic body has the following characteristics with respect to the instantaneous spring constant k defined by k = DELTA F / DELTAx, where x denotes the displacement of the elastic body by the force F applied by the pressing means.

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

When the displacement 0 <x <x ₁ , the instantaneous spring constant k 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

_{k 1> 0, k 2 ≤0} , k 3> 0 is satisfied the condition.

FIGS. 1 and 2 illustrate the elastic characteristics as described above.

Assuming that the displacement when pressing the elastic body with the pressing means is the depth x, the initial depth is 0 and the depth when the snap-through-buckling occurs is x ₁ . The maximum displacement of the elastic body, that is, the depth when it touches the floor, can be expressed as x ₃ .

That is, as shown in FIG. 1, when pressed by the pressurizing means, the force must _first increase to deepen the depth. However, when the depth reaches (x ₁ ), the depth deepens naturally without increasing the force (between x ₁ and x ₂ ) When the force increases again, the area where the depth deepens (between x ₂ and x ₃ ) appears. At this time, if a depth having a force equal to the force at x ₁ between x ₂ and x ₃ is defined as x ₂ 'and the depth is measured while increasing the pressing force applied to the pressing means, the depth x ₁ It is pressed down to the depth x ₂ 'even if the force does not increase.

Examples of the elastic body having elastic properties as described above include, but are not limited to, buckling springs, snap-through buckling springs, disc springs, dome springs, 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 transmitting the cantilever displacement generated by the pressing means to the piezoelectric body.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail with reference to an embodiment shown in the accompanying drawings.

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

The displacement of the elastic body transmitted to the piezoelectric body can be generated by a pressing means for transmitting a force to the elastic body.

3 to 5 are schematic exploded perspective views of an electric energy generating device having a piezoelectric body according to various embodiments of the present invention. It should be understood that the present invention is not limited to such a structure, and various modifications are possible within the scope of the present invention.

3 to 5 illustrate the case where a disk spring is used as an elastic body, but the present invention is not limited thereto, and the elastic body according to the present invention may be used as long as it has elasticity as described above with reference to FIGS. 1 and 2 .

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

As means for accommodating the displacement transmitted by the elastic body, Fig. 3 shows an elastomeric material sheet 16 such as rubber or foam, Fig. 4 shows a ring-shaped structure 17 capable of providing space, Fig. And two or more columnar structures 18 that allow space to be formed by spacing the substrate on which the piezoelectric body is formed from other structures at a predetermined interval. In addition, various modifications may be possible.

The piezoelectric body 11 is supported on the first surface of the substrate 10. Although the piezoelectric body may be formed only on one side of the substrate as shown, the present invention is not limited thereto, and it is also possible to form the piezoelectric body on both sides of the substrate.

It is preferable that the substrate 10 has a material and a structure that supports the piezoelectric body and does not substantially limit the displacement of the piezoelectric body due to the displacement transmitted from the elastic body. For example, a material such as a copper plate or an aluminum plate which is thin and thin can be preferably used.

According to a preferred embodiment, the substrate 10 may be provided with insulating layers 10a and 10b on the first surface and on the opposite second surface, respectively.

The piezoelectric body 11 may be made of a piezoelectric single crystal or a piezoelectric material. For example, a piezoelectric single crystal or a piezoelectric ceramics containing no lead, or a piezoelectric polymer or the like. The piezoelectric single crystal has a structure in which fine particles having a certain structure are regularly arranged.

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

Specifically, for example, the piezoelectric single crystal may be a solid solution single crystal of a magnesium niobate (PMN) as a relaxor and a piezoelectric acid lead (PT). When a single crystal is used as a piezoelectric material in an acceleration sensor, the piezoelectric distortion is three times or more larger than that of a conventional piezoelectric material, the electromechanical coupling coefficient is large, and excellent piezoelectric characteristics are exhibited. As an alternative, a piezoelectric ceramic, for example, lead zirconate titanate (PZT) ceramic, which is one example of a known piezoelectric material, can be used.

A first electrode 12a is formed on a first surface of the piezoelectric body 11 and a second electrode 12b is formed on a second surface of the piezoelectric body 11 opposite to the first electrode 12a. The electrodes 12a and 12b are connected to the terminals of a circuit board (not shown) through unillustrated wiring. When the piezoelectric body 11 vibrates as described later, electric energy is generated, and the electric energy generated from the piezoelectric body 11 can be supplied to the electronic device on the circuit board through the wiring.

The disk spring 13 exemplified as an elastic body has a shape of a part or a dome as a whole and has an opening at the bottom and an opening at the top. In another example not shown in the drawing, the opening may be closed. The elastic body is not limited to the shape shown in Figs. 3 to 5, and any elastic body as described above with reference to Figs. 1 and 2 can be used without limitation.

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

If the force is removed after pushing the elastic body to the depth (x ₁ ) at which snap-through-buckling occurs, the reverse region (x ₁ -x ₂ ) where the spring constant is negative and the proportion It can be restored to its original position only after passing through the region (x ₂ -x ₃ ). 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, so that the piezoelectric body disposed at the lower portion of the elastic body can generate a force to move in the form of free vibration.

Therefore, in the present invention, an elastic body having a spring constant of k can be used.

Referring again to Figures 3 to 5, a button is disposed as a pressing means 15 capable of pressing the spring 13 on the top of the spring 13. The button may have any shape that allows the user to depress the spring 13. [ A protrusion that can be inserted into an opening formed in the upper portion of the spring 13 may be formed at the bottom of the pressing means 15 such as a button. An insulating layer 14 is formed on the bottom surface of the button so that electrical insulation is provided between the spring 13 and the button.

In the electric energy generating apparatus constructed 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 of 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. The pressing and restoring of the spring 13 The piezoelectric body 11 is vibrated. The vibration of the piezoelectric body 11 generates electric energy, and the generated electric energy can be supplied through the wiring connected to the electrodes 12a and 12b.

3 to 5 show the case where the elastic body is located between the pressing means and the piezoelectric body, but the present invention is not limited to this, and it is also possible to design the piezoelectric body to be positioned between the pressing means and the elastic body. In any case, if the displacement of the elastic body is transmitted to the piezoelectric body so that the piezoelectric body can be displaced, that is, can oscillate, the electric energy generating apparatus according to the present invention can be implemented.

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

Specifically, Fig. 6 is a schematic cross-sectional view of an apparatus for transferring a cantilever displacement to a piezoelectric body. A projection 26 is formed on the column 24 of the button 15 and the piezoelectric body 21 is formed on one or both surfaces of the substrate 23. The substrate 23 may be a circular substrate having an opening at the center, or may be a structure in which a plurality of rectangular substrates in the form of a springboard are arranged symmetrically with respect to the columns of the buttons.

6, when the button 25 is depressed, the protrusion 26 presses the inner end of the substrate 23 downward and the button 25 is further depressed to further lower the protrusion 26, So that the piezoelectric body 21 formed on the substrate 23 is vibrated. In this case, the substrate 23 simultaneously serves as an elastic body.

Only the spring constant of the bottom spring 27 (i.e., k ₄ ) is applied before the protrusion 26 contacts the cantilever substrate 23, and when the protrusion 26 contacts the substrate 23, the spring constant becomes large That is, k ₅ ). When the substrate 23 continues to be bent, the substrate 23 returns to the initial spring constant (k ₄ ) again. In other words, at the moment of bouncing, the transition from small spring constant k ₅ (the sum of the cantilever spring effect to the spring effect by the protrusion to the bottom spring effect) to small k ₄ occurs.

According to another embodiment, the electric energy generating apparatus according to the present invention may be a unit electric generator, and a plurality of unit generators may be aggregated into a series or parallel structure.

FIGS. 7A and 7B schematically show a state where an electric energy generating apparatus is mounted on an experimental apparatus for measuring a voltage of electric energy generated in the electric energy generating apparatus. FIG. FIG. 7A is an electric energy generating device having an elastic body according to the present invention, and FIG. 7B is an electric energy generating device having no elastic body.

7A, a metal plate 30 is supported by a support base 40, and a piezoelectric body 31, an elastic body 33, and a pressing means 35 are disposed on the metal plate 30. The metal plate 30 is in contact with the support base 40 through the insulating layers 30a and 30b and an 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 is formed as a rectangular parallelepiped having dimensions of approximately 1 cm x 0.5 cm x 0.1 mm as a whole, and the diameter of the bottom surface of the spring 33 is approximately 0.6 cm. Referring to FIG. 7B, the electric energy generating device shown in FIG. 7A is the same as the electric energy generating device shown in FIG. 7A except that the elastic member 33 is not provided. That is, the metal plate 31 is supported by the support table 40, and the piezoelectric body 31 and the pressing means 35 are disposed on the metal plate 31. [

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

8, the voltage generated in the electric energy generating device having the elastic body 33 is shown in the upper part 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, when the elastic body 33 is provided, a voltage having an absolute value of at most 3 volts is generated when the pressing means 35 is pressed, and when the pressing force of the spring is applied And in the case of removing the pressing force, it occurs in the form of free vibration once. On the other hand, when the elastic body 33 is not provided, the magnitude of the absolute value of the voltage is less than 0.5 volts. In FIG. 8, the wave shape of about 0.2-0.3 volts at about 60 Hz is a signal generated by background noise due to minute vibration naturally occurring when the power is applied to the experimental apparatus, and is independent of the signal output from the pressing device.

FIGS. 9A and 9B show an experiment and a result of mounting an electric energy generating device according to the present invention on a mobile phone home button. FIG. 10 shows the result of measuring the voltage generation by repeatedly pressing the home button in the experimental apparatus of FIGS. 9A and 9B. It can be seen that a voltage of about 8 V is constantly generated even in 100 times and 1000 times of repetition.

The electric energy generating apparatus according to the present invention can be applied in various ways. For example, it can be used as a non-power remote control, a non-power keyboard, a non-power door lock, and a personal keypad. When the electric energy generator is applied to the remote control without power source, electric energy is generated only by a user pressing a button on the remote controller, and an infrared signal can be generated using the electric energy. Also, in a wireless keyboard that is not connected to a computer through a wired connection, a user can generate electrical energy only by typing on the keyboard, and transmit the keyboard signal to the computer body using the electrical energy.

10. Substrate
11.21. The piezoelectric body
13.23. Elastic body
15.25. Pressurizing means

Claims (8)

A piezoelectric body having at least two surfaces;
An elastic body disposed on at least one surface of the piezoelectric body and transmitting a displacement to the piezoelectric body; And
And means for accommodating displacement of the piezoelectric body is provided on another surface corresponding to the surface on which the elastic body is located. The method according to claim 1,
Further comprising a pressing means for transmitting a force to the elastic body,
The piezoelectric body is composed of a piezoelectric material layer having a first electrode provided on a first surface and a second electrode provided on a second surface,
Wherein the piezoelectric body is provided on one surface or both surfaces of the substrate. The method according to claim 1,
The elastic body is related to an instantaneous spring constant k defined by k = DELTA F / DELTAx, where x is the displacement of the elastic body by the force F applied by the pressing means,
When the displacements x ₁ , x ₂ and x ₃ are x ₁ < x ₂ < x ₃
When the displacement 0 <x <x ₁ , the instantaneous spring constant k 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
_{k 1> 0, k 2 ≤0} , k 3> An electric energy generating means having the elastic properties satisfying the condition 0. 3. The method of claim 2,
Wherein the substrate has a material and a structure that supports the piezoelectric body and does not substantially limit the displacement of the piezoelectric body due to the displacement transmitted from the elastic body. The method according to claim 1,
Wherein the piezoelectric body is made of a piezoelectric single crystal or a piezoelectric material. The method according to claim 1,
Wherein said piezoelectric body has piezoelectric characteristics of a d33, d15, or d31 mode. 3. The method of claim 2,
The substrate plays the role of the elastic body without a separate elastic body,
Wherein the substrate has a structure for transmitting the cantilever displacement generated by the pressing means to the piezoelectric body. An electric energy generating device according to any one of claims 1 to 7, wherein the electric power generating device is a unit electric power generating body, and a plurality of unit generators are collected in a series or parallel structure.

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