KR100795192B1 - Film speaker using multi layered O-3 type piezoelectric composite and their joined unit and method of producing the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a film speaker using a 0-3 type piezoelectric composite, wherein a lower electrode, 0-3 type composite (piezoelectric powder + polymer) using a conductor such as ITO, Cu, Al, or a conductive polymer on a base film A piezoelectric composite layer using a matrix) as a raw material, and a thin speaker structure formed by repeating the steps of sequentially forming an upper electrode such as Ag, Carbon, Cu, Al, etc., in a square or a circle, and having a length, width, or radial direction. It relates to a laminated film speaker for generating sound using the vibration mode of.

Film Speaker, Piezo, Composite, Printed, Laminated, Adhesion

Description

Multilayered piezoelectric composite film speaker using O-3 type piezoelectric composite and its manufacturing method {Film speaker using multi layered O-3 type piezoelectric composite and their joined unit and method of producing the same}

1 is a structural diagram of a single unit of a laminated piezoelectric composite speaker according to an embodiment of the present invention.

Figure 2 is a laminated structure diagram of a laminated piezoelectric composite speaker according to an embodiment of the present invention.

3 and 4 is a conceptual diagram of the length and width vibration mode of the laminated piezoelectric composite speaker according to an embodiment of the present invention.

Figure 5 is a polarization direction diagram of a three-layer piezoelectric composite speaker according to an embodiment of the present invention.

Figure 6 is a polarization direction diagram of a four-layer piezoelectric composite speaker according to an embodiment of the present invention.

7 is a conceptual diagram illustrating a radial vibration mode of a laminated piezoelectric composite speaker according to an exemplary embodiment of the present invention.

8 is a structural diagram of a laminated piezoelectric composite speaker according to an embodiment of the present invention, which is curved.

9 is a structural diagram of a laminated piezoelectric composite speaker according to another embodiment of the present invention.

10 is a structural diagram of a laminated piezoelectric composite speaker according to an embodiment of the present invention having a reflector.

※ Explanation of code about main part of drawing ※

1: base film 2: lower electrode

3: first piezoelectric composite 4: first upper electrode

31: second piezoelectric composite 41: second upper electrode

5: polarization direction 6: wiring

7: vibration direction 10: film speaker

20: reflector

The present invention relates to a method for manufacturing a laminated and adhesive film speaker using an O-3 type piezoelectric composite, wherein a lower electrode, 0-3 type composite (piezoelectric) using a conductor such as ITO, Cu, Al, or a conductive polymer on a base film Powder or polymer matrix), and a thin speaker structure formed by repeating the steps of sequentially forming the upper electrode such as Ag, Carbon, Cu, Al, etc., in a square or a circle, and having a length, width, Or it relates to a laminated film speaker for generating sound using a radial vibration mode.

The loudspeaker according to the conventional moving voice coil diaphragm method can faithfully reproduce the sound, but the structure is complicated, the cabinet space cannot be miniaturized, and takes an inefficient method of converting electrical power into acoustic power. .

Meanwhile, in order to compensate for this, a technology of using a film speaker using a polyvinylidene difluoride (PVDF), which is a piezoelectric polymer, is developed. However, in case of the film speaker using PVDF, the price of PVDF film is high, and d33 value is low to use as a speaker, and high voltage (approximately 100V or more) must be applied, and a separate high voltage (approximately 100V or more) is required to apply high voltage. Since a boost amplifier is required and the impedance of the film is large, a transformer must be used for impedance matching, and as the size becomes smaller, the acoustic characteristics in the low range are sharply degraded.

In addition, the existing magnet speaker also has a thickness limit of about 3mm, the magnetic field is rapidly weakened if it is less than 2mm it was impossible to use. In addition, the conventional piezoelectric polymer film speaker was not able to be used because the size of the piezoelectric polymer speaker rapidly lowered the characteristics of the bass region and the sound pressure became weak.

In order to solve this problem of the existing speaker, the present inventor has proposed a "film speaker using the O-3 type piezoelectric composite and its manufacturing method" of Korean Patent Application No. 10-2005-0121622. The patent-pending invention relates to a single-layer film speaker and a lamination method, and forms a lower electrode using a conductor such as ITO, Cu, Al, or a conductive polymer to provide conductivity to a base film, and forms an O-3 composite. (PZT powder + polymer matrix) is formed by piezoelectric composite layer vibrating according to electric signal by printing method or doctor blade method, and printing or depositing upper electrode such as Ag, Carbon, Cu, Al on top The present invention relates to a film speaker, which is formed by a method and polarized to be used as a thin speaker.

In the case of the film-type speaker, it is easy to manufacture, inexpensive to manufacture, and has an advantage of being ultra-thin and flexible, while mainly using a vibration mode in the thickness direction, the bass side becomes weak in the audible frequency region, and the size (width The threshold of the bass region changes depending on the length of the bass, and the thickness direction mode has a disadvantage in that the length direction is too short to vibrate a high frequency band outside the human audible frequency region.

The present invention is to improve the disadvantages and problems of the prior art as described above, to provide a film-type speaker and a method for manufacturing the same that is capable of improving the acoustic characteristics through the lamination or adhesion in a multi-layer structure to improve the acoustic characteristics. It is for.

In addition, the present invention is to provide a specific lamination method for improving the characteristics of the laminated piezoelectric composite film speaker, a method of adhering two or more piezoelectric composite film speakers to improve the characteristics, and a polarization method.

On the other hand, the present invention is to provide a manufacturing method for realizing the optimal vibration mode by implementing a laminated piezoelectric composite film speaker in a predetermined shape.

In addition, the present invention is to provide a laminated piezoelectric composite film-type speaker excellent in acoustic characteristics even when manufactured in a small size and a method of manufacturing the same.

In order to achieve the above object, the piezoelectric composite speaker according to the present invention has a predetermined shape designed according to acoustic characteristics, such as forming a lower electrode 2 on the base film 1 and having circular, rectangular, and band shapes as shown in FIG. 1. The piezoelectric composite 3 is formed on the base film 1 on which the lower electrode 2 is formed by printing or a doctor blade method, and the upper electrode 4 is formed thereon as a basic structure.

That is, the upper electrode 4 and the lower electrode 2 are provided with a terminal (not shown) for applying an external sound source signal as a single unit, and then the piezoelectric composite 3 is laminated or two or more layers. It is one of the objects of the present invention to improve properties by adhering more than a single unit. Hereinafter, a manufacturing method of a single unit will be described, but for the matters which are not sufficiently described herein, the film speaker using the "O-3 type piezoelectric composite of Korean Patent Application No. 10-2005-0121622 of the same inventor, and its manufacturing method "I will follow.

As the base film 1, polymer films such as polyethylene naphthalate (PEN) and polyethylene terephtalate (PET), polystyrene (PS), etc., having a thickness of 15 to 100 μm are used, etc. The base film 1 has various colors such as pattern printing. Decorations such as patterns and patterns may be provided.

The lower electrode 2 is formed on the base film 1 by printing Ag paste, carbon paste, conductive polymer, or depositing a conductive material such as Cu, Al, Ag, ITO.

The condition that the lower electrode 2 layer should have is more thermally stable than the piezoelectric composite 3 film to be placed thereon, exhibits low sheet resistance, and mechanically has a low Young's modulus.

Ag paste and carbon paste have proper viscosity for printing, and Ag or Carbon particles (particle size is about 10㎛) are mixed with solvent and binder, and drying temperature is less than about 150 degrees. Low temperature electrode material.

Conductive polymers include conductive polymers such as polyaniline, polythiophene, PEDOT (poly (3,4-ethylene-dioxythiophene)), polypyrrole, PPV (polyphenylenevinylene), derivatives thereof, and organic conductors.

The piezoelectric composite 3 layer is formed on the lower electrode 2 by using an O-3 type piezoelectric composite. 0-3 type piezoelectric composite is a type in which piezoelectric powder is evenly distributed in the polymer matrix without any orientation, and the piezoelectric powder is not connected in any direction of the x, y, z axis, and the polymer matrix is formed of x, y, z It has a structure that is connected in three directions.
The 0-3 type piezoelectric composite 3 of the present invention differs from the conventional 0-3 type piezoelectric composite in that it is composed of a mixture of piezoelectric powder and PVDF matrix. That is, the 0-3 type piezoelectric composite 3 of the present invention uses the piezoelectric polymer PVDF as a polymer matrix and mixes a separate piezoelectric powder in the PVDF polymer matrix, thereby improving piezoelectricity. Composite (3).

In the case of the piezoelectric composite 3, the dielectric constant is large and the loss tangent to frequency is stably small, and the leakage current should be minimized. To this end, it is necessary to reduce the thickness or increase the area of the piezoelectric composite 3 and to use piezoelectric powder having a high dielectric constant.

The upper electrode 4 on the piezoelectric composite 3 is also made of the same material as the lower electrode 2.

Figure 2 is a cross-sectional view of a laminated piezoelectric composite film speaker according to an embodiment of the present invention made by stacking a single unit manufactured through the above process.

In the laminated piezoelectric composite speaker, a lower electrode 2 is formed on the base film 1, and a first piezoelectric composite 3 having a predetermined shape is formed on the base film 1 on which the lower electrode 2 is formed. The first upper electrode 4 is formed thereon, and the second piezoelectric composite 31 is formed on the upper electrode 4 in a predetermined shape. By repeating the process of forming the second piezoelectric composite 31 and the second upper electrode 41 again thereon, a laminated piezoelectric composite film speaker having a two-layer structure as shown in FIG. 2 may be formed, for example, three layers The multilayer piezoelectric composite film speaker manufacture of the above multilayer structure is possible.

Subsequently, the piezoelectric composites 3 and 31 are polarized by applying an electric field of 4 to 7 KV / mm (about 1 MV / cm in the case of a conventional PVDF film) to impart piezoelectricity. The polarization method is a direct field application method or corona polarization. The method can be selected and polarized at a temperature of about 80 ~ 120 ℃, and the d33 value is about 20 ~ 100pC / N (when using lamination and bonding method, it depends on the number of layers and increases as the number of layers increases). It is preferable to have.

The polarization direction is such that the directions of the first piezoelectric composite 3 and the second piezoelectric composite 31 coincide, and the polarization process is primarily performed by applying a high voltage to the lower electrode 2 and the first upper electrode 4. Secondly, a high voltage is applied to the first upper electrode 4 and the second upper electrode 41. In the case of the laminated piezoelectric composite film speaker manufactured through the first and second polarization processes, the polarization directions are coincident as shown in FIG. 2.

When the laminated piezoelectric composite film speaker is operated by the wiring 6 as shown in FIG. 2, as shown in FIG. 3, the positive electrode is applied to the second upper electrode and the negative electrode is applied to the lower electrode. As the thickness of the upper piezoelectric composite increases in width and length, the lower piezoelectric composite decreases in thickness and increases in width and length, resulting in bending as shown in FIG. 4. If the polarity is reversed, the deflection is reversed, and the bending direction is changed according to the frequency of the applied voltage, thereby generating a force that pushes air and thus emits sound. As a result, the laminated composite film speaker in FIGS. 3 and 4 operates using length and width vibration modes. When the length and width vibration modes are used, compared to the case where only the vibration mode 7 in the thickness direction exists, such as the single layer piezoelectric composite film speaker illustrated in FIG. Is enlarged. In the case of a single unit as shown in Fig. 1, since the vibration mode 7 in the thickness direction is used, the bass side becomes weak in the audible frequency region, and the threshold of the bass region changes depending on the magnitude (width and length). In addition, the thickness direction mode is too short in length to vibrate in a high frequency band outside the human audible frequency range.

Meanwhile, a case in which the laminated piezoelectric composite film speaker is manufactured using a three-layer or four-layer composite is shown in FIGS. 5 and 6, respectively.

When the polarization direction is formed as shown in FIGS. 5 and 6, the same length and width vibration mode effects as in FIG. 3 occur, and the displacement is 3 to 4 times that of a single unit. In addition, when using the vibration mode in the length and width direction as shown in Figs. 5 and 6 there is a sufficient length and width to extend the sound range to the bass region.

Figure 7 relates to a piezoelectric composite speaker using the radial vibration mode of the present invention.

When the piezoelectric composite speaker is manufactured in a circular shape and two or more units are stacked in the polarization direction in the same manner as in FIG. 2, 5, or 6, the radial vibration mode is used to expand the sound range to the low range. Can be. In other words, compared to the case of using the vibration mode in the length and width direction using the piezoelectric composite of the square, when using the vibration mode in the radial direction using the circular piezoelectric composite, since the same vibration waveform in the radial direction will have the distortion The phenomenon can be reduced.

That is, in the case of a rectangular shape, in the main vibration mode, the longer side in the length or width direction becomes the main vibration direction, and the vibration displacement is also large, and the shorter side vibrates at the vibration frequency following the main vibration and the vibration displacement. Decreases with the ratio of lengths. In the longitudinal main vibration mode, the primary vibration is performed in the region with the lowest vibration frequency, and the secondary vibration is performed at a higher vibration frequency. In this manner, the third and fourth vibrations are performed. At this time, when the secondary vibration in the longitudinal direction and the vibration in the width direction overlap, an offset effect is obtained, resulting in a decrease in volume and distortion. On the other hand, in the radial vibration mode, since only the first, second, third, ..., n-th order vibrations occur in the radial direction, there is no phenomenon of canceling or distorting the vibration mode.

Meanwhile, as shown in FIG. 8, when the speaker in the radial vibration mode is formed into a curved surface, that is, a dome shape, the amplitude is further expanded to obtain a larger volume. In the case of the piezoelectric composite film speaker manufactured by the lamination method, the band of sound is changed according to the radius of curvature, as in the piezoelectric composite film speaker of a single unit, and the use frequency band is adjusted by adjusting the radius of curvature according to the intended use.

Meanwhile, even when two or more single units are adhered to each other, the polarizing directions may be arranged in the same manner as the above-described multilayer piezoelectric composite speaker. At this time, a common double-sided tape, epoxy resin, etc. may be used for adhesion, and in some cases, a metal plate may be inserted between layers to reduce attenuation of amplitude.

9 is a cross-sectional view of a laminated piezoelectric composite film speaker structure according to another embodiment of the present invention.

As shown in FIG. 9, the base film 1 may use a polymer film such as PET or PEN, or a metal plate such as Cu or phosphor bronze plate, or may use other plastic material. When using a conductive metal plate such as Cu or phosphor bronze, the first lower electrode 2 and the second lower electrode 21 may be omitted.

In the manufacturing process of the laminated piezoelectric composite film speaker illustrated in FIG. 9, the first lower electrode 2, the first piezoelectric composite 3, and the first upper electrode 4 are deposited on a base film 1, printed, The second lower electrode 21, the second piezoelectric composite 31, and the second upper electrode 41 are formed on the back surface of the base film 1 by the same method. In the polarization direction 5 shown in FIG. 9, for example, a high electric field of 7 KV / mm or more is added to polarize the polarizer, and in this case, the polarizer 5 may be manufactured in a desired shape such as a square or a circle.

In the case of the film speaker of the present invention thus produced, there is no direction of sound and has a directivity of 360 degrees. However, when the 360 degree of directionality is not necessary, the sound emitted backward may be reflected forward to increase the volume, and a structure thereof is shown in FIG. 10. As shown in FIG. 10, a reflecting plate 20 may be disposed on the rear surface of the film speaker 10 without absorbing the sound to reflect the sound toward the rear.

In the case of the film speaker, as described above with reference to FIG. 8, a certain amount of curvature gives an effect of enlarging the volume. As the radius of curvature increases, the sound intensity does not increase but the bass comes out better, and the radius of curvature decreases. The loudness increases, but the cutoff frequency of the bass rises, resulting in a weak bass. In this case, when the reflection plate 20 is placed on the rear surface of the film speaker 10 to reflect the sound forward, the radius of curvature may be increased to reinforce the bass region, and at the same time, the rear radiating sound may be effectively reflected forward.

In the above, the present invention has been described through embodiments of the present invention, but the scope of the present invention is not limited to the described embodiments, and various modifications or changes by those skilled in the art within the scope of the claims based on the appended claims. This possibility is self-evident.

Since the laminated piezoelectric composite film speaker of the present invention uses the printing and doctor blade method, it is excellent in mass productivity and easy to mass produce and manufacture by forming an electrode by a method such as silk screen or vapor deposition, and also by a simple lamination method. The performance can be improved, and the effect as a speaker is equally increased even when the piezoelectric composite units are bonded to produce a film speaker.

The laminated piezoelectric composite film speaker of the present invention is easy to adjust the characteristics and control the size through the adjustment of the printing thickness, the electrode control, the selection of the base film, the number of lamination, the adjustment of the polarization characteristics, the change of the adhesion method, It is effective to mass-produce thin and lightweight products with various designs with desired specifications.

Various patterns and advertisements can be easily printed by printing patterns on the base film surface of the laminated piezoelectric composite film speaker of the present invention, and various base films of various designs may be used as they are.

Since the laminated piezoelectric composite film speaker of the present invention can be driven at a lower voltage than the conventional PVDF piezoelectric film, it is possible to prevent loss due to excessive voltage boost, low impedance and easy matching, and power consumption can be reduced.

In addition, the laminated piezoelectric film speaker of the present invention can be easily controlled by adjusting the ratio of piezoelectric powder: PVDF matrix.

In addition, the piezoelectric composite film speaker of the present invention can linearly improve performance by laminating, and can use vibration modes in the length and width directions.

In addition, the piezoelectric composite film speaker of the present invention is capable of listening to sound regardless of a specific position because the middle and high sound range is superior to the existing speaker and the sound spreading is wide.

In addition, the piezoelectric composite film speaker of the present invention can be applied to more areas because the low-end band is superior to the conventional PVDF piezoelectric film speaker, and can be manufactured as an ultra-thin micro speaker because it can be reduced in size unlike conventional PVDF piezoelectric film speakers. It can be applied to small mobile devices such as mobile phones and DMB phones.

In addition, since the piezoelectric composite film speaker of the present invention can be easily bent, it is possible to adjust the high and low sound of the sound according to the degree of bending, and when forming a curved surface (dome), while controlling the sound range according to the radius of curvature and concentrating the sound pressure It can be made to have a larger volume, and the sound can be emitted to the front and rear surfaces of the film speaker.

In addition, in the piezoelectric composite film speaker of the present invention, it is possible to control the characteristics of the bass region through the appropriate ratio and additives of the piezoelectric powder and the polymer during the manufacture of the composite.

In addition, in the case of the piezoelectric composite film speaker of the present invention, the shape can be freely formed into a circular quadrangle or the like, and the characteristics of the bass region can be enhanced by setting the longitudinal direction, the width direction, and the radial vibration mode according to the shape.

In addition, in the case of the piezoelectric composite film speaker of the present invention, the acoustic characteristics may be improved by reflecting the sound radiated to the rear side forward by using a reflecting plate.

In addition, in the case of the piezoelectric composite film speaker of the present invention, the use of the length, width, and radial vibration mode using the lamination and bonding technology of the present invention can overcome the degradation of the bass characteristics, which is a problem of the existing film speaker.

In addition, the piezoelectric composite film speaker of the present invention may be widely applied to various applications of a microphone and a piezoelectric sensor in addition to the film type speaker.

Claims (12)

A base film formed of a polymer film; And A single unit piezoelectric composite structure including a lower electrode layer, a 0-3 type piezoelectric composite layer disposed on the lower electrode layer and evenly distributed in the PVDF polymer matrix, and an upper electrode layer formed on the piezoelectric composite. , The piezoelectric composite film speaker of claim 1, wherein the piezoelectric composite structure of the single unit is laminated two or more times on the base film. The method of claim 1, And the single unit piezoelectric composite structure is stacked upward on the top surface of the base film. The method of claim 1, And the single unit piezoelectric composite structure is laminated on both sides of the base film. The method of claim 2 or 3, The single unit piezoelectric composite structure is circular, and the laminated piezoelectric composite film speaker, characterized in that it operates mainly in the radial vibration mode. The method of claim 2 or 3, The single unit piezoelectric composite structure has a rectangular shape, and laminated piezoelectric composite film speaker, characterized in that it operates mainly in the longitudinal and widthwise vibration mode. The method of claim 4, wherein And the single unit piezoelectric composite structure is molded into a dome shape. The method of claim 4, wherein The 0-3 type piezoelectric composite layer is laminated piezoelectric composite film speaker, characterized in that formed on the lower electrode layer by printing or a doctor blade method. The method of claim 5, The 0-3 type piezoelectric composite layer is laminated piezoelectric composite film speaker, characterized in that formed on the lower electrode layer by printing or a doctor blade method. delete delete delete delete

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