KR102234578B1 - Piezoelectric vibration module - Google Patents

Abstract

The present invention relates to a piezoelectric vibration module, a vibration plate having one side fixed to a fixed part of a case, a piezoelectric body in contact with the vibration plate, a flexible circuit board capable of applying power to the piezoelectric body, and the other side of the vibration plate. It includes the weight body to be combined. In addition, only one side of the vibration plate can be fixed to the case to lower the driving frequency and the length of the vibration plate can be shortened.A weight body is attached to the unfixed end of the vibration plate to further lower the driving frequency and increase the vibration force, and piezoelectric vibration Its purpose is to be able to make the overall thickness of the module thinner.

Description

Piezoelectric vibration module

The present invention relates to a piezoelectric vibration module, and more particularly, to a device mounted in a portable electronic device to generate vibration.

In general, in portable electronic devices such as mobile phones, e-book terminals, game consoles, tablet PCs, and PMPs, the vibration function is used as a notification function for information such as messages and phone calls, and a haptic function to enhance the user's sense of operation. However, according to the development of technology, a vibration generating device for implementing such a vibration function is required to be miniaturized, integrated, diversified, and highly functional.

Vibration generating devices are developed and applied in various forms using piezoelectric materials in order to allow users to have a more intuitive experience and to feel a variety of tactile sensations. When pressure is applied to a piezoelectric material, a voltage is obtained (the piezoelectric effect that converts mechanical energy into electrical energy), and when a voltage is applied on the contrary, the volume or length increases or decreases due to the pressure change in the piezoelectric material. Reverse piezoelectric effect).

In the piezoelectric vibration module using the properties of such a piezoelectric material, the piezoelectric material that vibrates when AC power is applied is bonded with an adhesive to one side of a vibration plate in which both or the center part is fixed, and a weight body is attached to lower the driving frequency and increase the vibration force. It is a common form.

In Korean Patent Registration No. 10-1319974, it can be seen that both sides of the vibration plate of the piezoelectric vibration module are fixed to the case. When both ends of the vibrating plate are fixed in this way, strong vibration occurs in the center of the vibrating plate to which the piezoelectric material is attached, and there is a high possibility that problems such as damage and cracking of the piezoelectric material may occur during driving, as well as lowering the driving frequency. In order to maximize vibration, the length of the vibration plate is lengthened and the weight is also heavy.

KR 1319974 B1

The present invention is to solve the above-described problem, and an object of the present invention is to fix one side of a vibration plate to a case to lower a driving frequency and to shorten the length of the vibration plate.

Also, by attaching a weight body to the other end of the vibration plate, the purpose of this is to further lower the driving frequency, increase the vibration force, and make the overall thickness of the piezoelectric vibration module thinner.

A piezoelectric vibration module for solving the above problems includes a vibration plate having one side fixed to a fixing part of a case, a piezoelectric body in contact with the vibration plate, a flexible circuit board capable of applying power to the piezoelectric body, and the vibration plate. It includes a weight body coupled to the other side of the.

The piezoelectric body may be attached to both sides of the vibration plate, and an adhesive is bonded between the vibration plates as a medium.

In addition, a groove having a thickness of 1 to 50% of the vibration plate is formed on the vibration plate corresponding to both ends or one end of the piezoelectric body, and the adhesive is introduced into the groove.

The material of the vibration plate is characterized in that the coefficient of thermal expansion is between 0.5 ~ 20 * (10-6 cm/cm/℃), and protrusion-shaped irregularities are formed on the surface of the vibration plate, and the overall surface roughness of the vibration plate is averaged. It is characterized in that (Ra) is 0.5um or more.

The piezoelectric body includes a green sheet, a plurality of first electrodes, a plurality of second electrodes, and an external electrode pad, and the first electrode and the second electrode have a curved edge and the first electrode on one surface of the green sheet, The second electrodes are alternately stacked, and an interval between each of the first and second electrodes is 50 μm or less.

A distance between the boundary of the green sheet and the boundary of the first electrode and the boundary of the second electrode is at least 0.05 mm, and a via hole having a diameter of 50 μm or more is formed in the first electrode and the second electrode.

The external electrode pad is formed between the piezoelectric material and the flexible circuit board, and the first electrode and the second electrode are connected to each other with a plurality of the first electrodes or the plurality of second electrodes, and each external electrode pad It is characterized in that it is also connected to.

The weight body is characterized in that the weight body coupling portion coupled to the vibration plate and extending from the weight body coupling portion and spaced apart from a side surface of the vibration plate by a predetermined distance or more.

The fixing part is characterized in that it is coupled to one side of the vibration plate and the side surface of the case.

And a stopper facing the end portion of the vibration plate and fixed to both surfaces of the case.

According to the present invention, the piezoelectric vibration module can be manufactured to reduce the driving frequency and shorten the length of the vibration plate by fixing one side of the vibration plate to the case.

In addition, by attaching a weight body to the unfixed end of the vibration plate, the driving frequency can be further lowered, the vibration force doubled, and the overall thickness of the piezoelectric vibration module can be made thin.

1 is a diagram showing a piezoelectric vibration module according to an embodiment of the present invention.
2 is a front view of a piezoelectric vibration module according to an embodiment of the present invention.
3 is a plan view of a piezoelectric vibration module according to an embodiment of the present invention.
4 is a right side view of a piezoelectric vibration module according to an embodiment of the present invention.
5 is a view showing a piezoelectric attachment method of a piezoelectric vibration module according to another embodiment of the present invention.
6 is a view showing a first electrode and a second electrode according to an embodiment of the present invention.
7 is a diagram illustrating a stack of a plurality of first electrodes and a plurality of second electrodes according to an exemplary embodiment of the present invention.
8 is a view showing a short prevention groove according to an embodiment of the present invention.

Hereinafter, the configuration and operation of a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram showing a piezoelectric vibration module according to an embodiment of the present invention.

Referring to FIG. 1, a piezoelectric vibration module according to an embodiment of the present invention includes a flexible circuit board (not shown), a piezoelectric body 200 that is coupled to a flexible circuit board and contracts and expands by an AC voltage, and a piezoelectric body and an adhesive. It includes a vibration plate 300 attached through, a weight body 400 attached to the vibration plate to double the vibration force and lower the frequency.

The flexible circuit board (not shown) is a component for applying AC power to the piezoelectric body 200, and the piezoelectric body 200 vibrates in various directions according to contraction or expansion in the piezoelectric vibration module, so that it can be bent concave or convexly. It is made of a metal material having flexibility and elasticity and can be combined with the piezoelectric body 200.

The piezoelectric body 200 is manufactured by printing a first electrode and a second electrode, which are internal electrode patterns of a certain shape, on one surface of a green sheet having a thickness of several to tens of um by a conductive paste process, and stacking each electrode alternately. When power is applied from the outside through the power supply device, the piezoelectric body 200 contracts or expands in the longitudinal direction according to the direction in which the voltage is applied. Accordingly, a flexible circuit board (not shown) to which the piezoelectric body 200 having such characteristics is coupled is also bent according to the contraction or expansion of the piezoelectric body 200 to generate vibration.

The green sheet is generally a sheet for printing an electrode or passive element having excellent electrical conductivity, and a raw material powder composed of a PZT-based (PbZrTiO3) piezoelectric ceramic may be used.

After measuring about 6wt% of PVB-based binder as an additive to the prepared raw material powder, it is dissolved in toluene/alcohol-based solvent and added. Thereafter, a slurry is prepared by milling and mixing for about 24 hours with a small ball mill. A green sheet having a desired size can be manufactured by using such a slurry by a method such as a doctor blade.

A pattern for internal electrodes can be printed on the manufactured green sheet, but the internal electrode includes Ag or AgPd, but since Ag has a melting point of approximately 960 degrees, it can be melted during sintering after the green sheet is manufactured, so AgPd is mainly used as an internal electrode. Depending on the sintering temperature according to the material of the substrate, Ag can also be used as an internal electrode.

After stacking the first electrode and the second electrode as many as a desired number of layers on one surface of the produced green sheet, they are integrated through firing, and the stacked electrode is cut to a desired size through a dicing process. A method of firing after knife cut before firing and a method of cutting will be described in detail with reference to FIG. 6.

In addition, in configuring the piezoelectric body 200, the first electrode of each stacked electrode layer must be connected to the first electrode and the second electrode must be connected to the second electrode, and power must be applied to each electrode. An electrode pad may be formed outside the piezoelectric body 200. A method of stacking electrodes and a method of connecting external electrode pads to the stacked electrodes will be described in detail with reference to FIG. 7.

The vibration plate 300 is a long rod plate shape, the piezoelectric body 200 and one side are bonded with an adhesive, the side surface is fixed to one side of the case (not shown), and the weight 400 is connected to the end of the vibration plate. have.

When attaching the vibration plate 300 and the piezoelectric body 200, an adhesive is used, and the adhesive may be a thermal curing resin, a UV curing resin, a room temperature curing resin, a thermal curing tape, or an anaerobic adhesive. Although the thermosetting adhesive has an advantage of excellent adhesion, since the bonding is performed at a high temperature, the coefficients of thermal expansion of the piezoelectric body 200 and the vibration plate 300 are different from each other, so that the piezoelectric body 200 and the vibration plate 300 can be manufactured in a curved shape rather than a flat shape.

In order to prevent such a problem, the material of the vibration plate 300 may be Invar or Kovar, which has a similar thermal expansion coefficient to that of the piezoelectric body 200, and the difference in thermal expansion coefficient is large, but the price is low. In general, a material having a thermal expansion coefficient of 0.5 to 20 * (10-6 ㎝/cm/℃) may be used, but is not limited thereto.

In order to more strongly bond the piezoelectric material 200 and the vibrating plate 300, a protrusion-shaped unevenness can be generated on the surface of the vibrating plate 300 to which the piezoelectric material 200 is bonded. It can be manufactured to maintain a stronger adhesion with 200. The bonding of the piezoelectric body 200 and the vibration plate 300 will be described in detail with reference to FIG. 8.

In addition, when only one side of the vibration plate 300 is fixed to the case, the vibration plate 300 vibrates together according to the vibration of the piezoelectric body 200, and the largest vibration is generated at the end of the vibration plate. In addition to implementing vibration, the driving frequency can be lowered, and the length can be made shorter than that of the existing central fixed vibration plate 300 method.

The weight body 400 is coupled to the end of the vibration plate, and the material of the weight body 400 may be tungsten having a large specific gravity, but the material is not limited, and any material capable of exhibiting high weight even with a small volume may be used. . As the specific gravity of the weight body 400 increases, the driving frequency may be lowered and the vibration may be stronger when manufacturing a small/ultra-thin piezoelectric vibration module. The weight 400 will be described in detail in FIGS. 3 and 4.

2 is a front view of a piezoelectric vibration module according to an embodiment of the present invention.

Referring to FIG. 2, a piezoelectric vibration module according to an embodiment of the present invention includes a flexible circuit board 100 bent at least once, a piezoelectric body 200 that is coupled to one surface of the flexible circuit board and contracts and expands by an AC voltage, and a piezoelectric body. And a vibration plate 300 attached through an adhesive, a weight 400 attached to the vibration plate to double the vibration force and lower the frequency, and a fixing part for fixing the vibration plate 300 to the case 600 ( 601), and a stopper 500 for limiting the vibration width of the weight body 400.

Prior to the description of FIG. 2, components other than the structure of the stopper 500 and the fixing part 601 have already been described in FIG. 1, so descriptions excluding the stopper and the fixing part will be omitted.

The stopper 500 is installed on both sides inside the case 600 and faces the vibration plate end portion 301 and the weight coupling portion 401. The stopper 500 may be used as a stopper by adhering a material such as a cushioning tape or a foam tape having a certain thickness to the case in order to secure reliability due to the same material as the vibration plate 300 or external impact. The stopper is spaced apart from the vibration plate end portion 301 and the weight 400 by a predetermined distance or more, so that the vibration width can be limited when the piezoelectric body 200 vibrates by an AC voltage.

The fixing part 601 is coupled to one side of the vibration plate 300 and the side surface of the case 600, and when the piezoelectric body 200 vibrates by an alternating voltage, it is connected to the piezoelectric body 200 and the piezoelectric body 200. The vibration plate 300 and the weight 400 are vibrated together, and the largest displacement due to vibration may be generated at the vibration plate end portion 301.

Accordingly, not only can the vibration frequency generated from the piezoelectric body 200 be reduced, but also the length of the vibration plate 300 can be shortened, thereby reducing the size of the overall piezoelectric vibration module and lowering the unit cost.

3 is a plan view of a piezoelectric vibration module according to an embodiment of the present invention, and FIG. 4 is a right side view of the piezoelectric vibration module according to an embodiment of the present invention.

Prior to the description of FIGS. 3 and 4, other components except for the coupling structure of the vibration plate end portion 301 and the weight body coupling portion 401 have already been described in FIG. 1, so that the vibration plate end portion and the weight body are coupled. Description except for the part will be omitted.

Referring to FIG. 3, the weight body 400 is manufactured in a'C' shape so that the weight body coupling portion 401 is coupled to the vibration plate end portion 301. In addition, the portion extending from the heavy body coupling portion 401 is spaced apart from the side surface of the vibration plate 300 by a predetermined distance or more, which serves to protect the piezoelectric body 200 from impact without interfering with the vibrational motion of the piezoelectric body 200. In addition, it plays a role in increasing the vibration. 4, too, the weight body 400 is manufactured in a'c' shape, which, as in FIG. 3, not only protects the shock within a range that does not interfere with the vibrational motion of the piezoelectric body 200, but also helps to increase the vibration. give.

5 is a view showing a piezoelectric attachment method of a piezoelectric vibration module according to another embodiment of the present invention.

Referring to FIG. 5, the piezoelectric vibration module is generally in a form in which the piezoelectric body 200 is coupled to the lower surface of the vibration plate 300 as shown in FIG. 5-1, but depending on the position to which the piezoelectric body 200 is attached, as shown in FIG. 5-2. The piezoelectric body 200 may be coupled to the upper surface of the vibration plate 300, or the piezoelectric body 200 may be coupled to both surfaces of the vibration plate 300 as shown in FIG. 5-3. In particular, when the piezoelectric body 200 is coupled to both sides of the vibration plate 300, it may generate a greater vibration than when coupled to one side.

6 is a view showing a first electrode and a second electrode according to an embodiment of the present invention.

6, the first electrode 201 and the second electrode 202 according to an embodiment of the present invention are cut to a uniform width so as not to be exposed to the outside to maintain a distance from the outside of the piezoelectric body 200. The spacing may be at least 0.05 mm or more.

This is because when the internal electrode is exposed to the external surface, when the piezoelectric vibration module is implemented by applying an AC voltage through the flexible circuit board 100, the distance between the first electrode 201 and the second electrode 202 becomes close and a short circuit occurs. This is to prevent the electrode from being exposed to the outside because the piezoelectric vibration module may not operate normally or may be damaged.

In addition, the piezoelectric body 200 is generally formed in a square shape. When manufacturing the first electrode 201 and the second electrode 202, the inner pattern corner portion of the square shape is formed in a curved shape (so that the corner portion has an R value). So that when an AC voltage is applied to the electrode, the voltage can be applied evenly without being concentrated on the vertex.

7 is a diagram illustrating a stack of a plurality of first electrodes 201 and a plurality of second electrodes 202 according to an exemplary embodiment of the present invention.

Referring to FIG. 7, according to an embodiment of the present invention, a plurality of first electrodes 201 and a plurality of second electrodes 202 are alternately replaced with a first electrode-a second electrode-a first electrode-a second electrode. It can be stacked with each other, the thickness of each layer can be adjusted, and the first electrode can be connected to the first electrode and the second electrode can be connected to the second electrode. In addition, since the external electrode pad 203 for applying power to the electrode is formed outside the piezoelectric body 200, the structure as shown in FIG. 7 may be configured so that the connected electrode and the external electrode pad 203 are coupled.

VCM (Voice coil motor) method, such as LRA (Linear Resonance Actuator), which is currently generally used, is driven at a low voltage with a driving voltage of 3Vrms or less, and the layer thickness of the piezoelectric material 200 used in a typical piezoelectric vibration module is 50~ When driving at 100um level, a fairly high AC voltage is required.

Due to such a high driving voltage, a driving circuit including a separate amplifier is required, and the unit cost of the entire product is increased. To solve this problem, the thickness of each layer of the piezoelectric body 200 is reduced to enable driving even at a low voltage of the LRA level. It can be implemented within 50um.

In order to connect the first electrode 201 and the second electrode 202 and connect the external electrode for applying power, a via hole of a predetermined size is formed in the first electrode 201 and the second electrode 202 to fill the electrode. Via filling method that connects each electrode can be used. As another method, after exposing a part of each electrode to the outside, a method of applying a conductive resin or conductive paste to the part and bonding it may be used.

In addition, the external electrode pad 203, which is coupled to the outer surface of the piezoelectric body 200 to apply an AC voltage, is attached to the flexible circuit board during the piezoelectric vibration module manufacturing process. A conductive resin or conductive paste may be used, and soldering. It can also be attached through.

8 is a view showing a short prevention groove according to an embodiment of the present invention.

According to FIG. 8, the surface roughness of the vibrating plate 300 to which the piezoelectric material 200 is bonded is determined in order to more strongly bond the piezoelectric material 200 and the vibrating plate 300 when the piezoelectric material 200 is bonded to the vibrating plate 300. It can be manufactured to maintain a stronger adhesive force with the piezoelectric body 200 by arbitrarily adjusting. As an example, an uneven protrusion may be formed, and Ra, which is a measure of the average roughness of the surface, may be 0.5 μm or more.

In addition, since the thickness of the adhesive is thin, the device may be short-circuited due to the side electrode of the piezoelectric body 200. In order to improve this, a vibration plate groove 302 is created at one or both ends where the vibration plate 300 and the piezoelectric material 200 abut, and the vibration plate groove 302 is filled with an adhesive. The thickness of the groove may be formed to about 1 to 50% of the thickness of the vibration plate 300, and suitably about 10 to 20% of the thickness of the vibration plate 300.

This prevents a short circuit that occurs when the vibration plate 300 and the piezoelectric material 200 come into contact with each other, so that voltage can be stably driven. Due to the effect of dispersing the stress due to the filled adhesive, stable operation is possible even if the piezoelectric vibration module is used for a long time.

As such, those of ordinary skill in the art to which the present invention pertains will recognize that the present invention can be implemented in other specific embodiments without changing the technical spirit or essential features thereof. Therefore, it should be understood that the above-described embodiments are only illustrative, and are not restrictive, limiting the scope. In addition, the flow charts shown in the drawings are merely a sequential order illustrated by way of example to achieve the most desirable results in carrying out the present invention, and of course, other additional steps may be provided or some steps may be deleted. .

In addition, this specification is not intended to limit the invention by the specific terms presented. Therefore, although the present invention has been described with reference to the above-described embodiments, those of ordinary skill in the art to which the present invention pertains without departing from the spirit of the present invention, modifications, changes and modifications to the embodiments, and Transformation can be applied.

100-flexible circuit board
200-piezoelectric
201-first electrode
202-second electrode
203-External electrode pad
300-vibrating plate
301-vibrating plate end
302-vibrating plate groove
400-heavy body
401-heavy body joint
500-stopper
600-case
601-Fixed part

Claims (19)

A vibration plate having one side fixed to the fixing part of the case;
A piezoelectric material in contact with the vibration plate;
A flexible circuit board capable of applying power to the piezoelectric material; And
A weight body coupled to the other side of the vibration plate;
Including,
The weight body,
As a C shape in which the vibration plate is accommodated, the vibration plate is accommodated by being spaced apart from the side surface of the vibration plate by a predetermined distance or more,
The cross-sectional shape in the direction perpendicular to the vibration plate is a c-shaped shape with an upper portion covered, and the cross-sectional shape in the horizontal direction on the vibration plate is a c-shaped shape in which the unfixed end of the vibration plate is blocked,
The vibration plate,
It is bent upward to support the end of the weight body at the non-fixed end,
Bonding the piezoelectric material and the adhesive as a medium,
A groove having a thickness of 1 to 50% of the vibration plate is formed at a position corresponding to one end or both ends of the piezoelectric body,
Piezoelectric vibration module, characterized in that the adhesive is introduced into the groove and coupled to the piezoelectric material.
delete delete delete delete delete The method of claim 1,
Piezoelectric vibration module, characterized in that the protrusion-shaped irregularities are formed on the surface of the vibration plate.
The method of claim 1,
Piezoelectric vibration module, characterized in that the total surface roughness (Ra) of the vibration plate is 0.5um or more.
The method of claim 1,
The piezoelectric body includes a green sheet, a plurality of first electrodes, a plurality of second electrodes, and an external electrode pad, the first electrode and the second electrode are alternately stacked on one surface of the green sheet, and the first The piezoelectric vibration module, characterized in that the electrode, the second electrode has a curved edge.
delete delete The method of claim 9,
Piezoelectric vibration module, characterized in that the spacing between each of the first electrode and the second electrode stacked on one surface of the green sheet is 50 μm or less.
The method of claim 9,
A piezoelectric vibration module, wherein a distance between the boundary of the green sheet and the boundary of the first electrode and the boundary of the second electrode is at least 0.05 mm or more.
The method of claim 9,
The piezoelectric vibration module, characterized in that a via hole having a diameter of 50 μm or more is formed in the first electrode and the second electrode.
delete delete The method of claim 1,
The weight body is a piezoelectric vibration module, characterized in that the weight body coupling portion coupled to the vibration plate and extending from the weight body coupling portion and spaced apart from a side surface of the vibration plate by a predetermined distance or more.
delete delete

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