KR20080075303A - Piezoelectric polymer speaker and method of manufacture thereof - Google Patents

Abstract

A piezoelectric polymer speaker and a manufacturing method thereof are provided to minimize loss of a piezoelectric polymer sheet by forming conductive polymer films without cutting the piezoelectric polymer sheet. A piezoelectric polymer speaker includes a piezoelectric polymer film(200), a polymer conductor film(202), an electrode(204), and a terminal(206). The piezoelectric polymer film has a predetermined shape and is surface-treated by using a corona method. The polymer conductor film is coated on both sides of the piezoelectric polymer film by being mixed with a binder and supplies the piezoelectric polymer film with power. The electrode is formed to be extended along an edge of the polymer conductor film. The terminal is extended outside the polymer conductor film from the electrode.

Description

Piezoelectric polymer speaker and method of manufacture

1 is a front view of a piezoelectric polymer speaker according to the prior art.

2 is a front view of a piezoelectric polymer speaker according to a preferred embodiment of the present invention.

Figure 3 is a graph showing the sound pressure for each frequency according to the resistance value of the polymer conductor film of the piezoelectric polymer speaker according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: piezoelectric polymer sheet 102: polymer conductor film

104: copper wire tape electrode 106: copper wire tape terminal

200 piezoelectric polymer film 202 polymer conductor film

204: electrode 206: terminal

208: Reinforcement Tape

The present invention relates to a piezoelectric polymer speaker, and in forming a conductive film on both sides of the polymer sheet, the film is formed on both sides of the sheet using a conductive polymer including a binder without processing the sheet separately.

In recent years, in accordance with the trend of miniaturization and thinning of home appliances, film-type speakers using thin piezoelectric elements have been developed in place of the conventional speakers.

The film-type speaker refers to a speaker configured to reproduce an acoustic signal by using a characteristic of a piezoelectric element that causes mechanical vibration when a voltage is applied.

Conventional speakers operate on the principle that vibrations of air are transmitted to the diaphragm when the electricity converted to sound connects and drops the electromagnet.

To produce this effect (sounding), a large-spaced device (speaker) with a heavy, fixed shape, such as a cone or an ellipse, was required.To make such a device, ceramics, the basic material of a conventional speaker, were molded at high temperature. Since several manufacturing processes are required, there is a problem that requires a complicated production line and a large number of people. In addition, the existing speaker is not only limited to printing in a limited size, but also has a design limitations and forms of deformation is impossible. In addition, there is a problem in that a speaker corresponding to the function needs to be attached to the high range.

To solve this problem, film speakers have been developed.

Using the surface modification technology applying plasma ion method, the surface of the material is changed into water-friendly property (hydrophilic) or water-free property (hydrophobic) so that the metal or conductive material does not adhere to the quilt, which could not be used as a speaker material Polyvinylidene Fluoride (PVDF) is a special plastic with piezoelectric properties. It is a special speaker that can be used for the same purpose as existing speakers by forming electrodes by changing the surface properties. At room temperature, the surface of the PVDF film is made hydrophilic to form an electrode, which can function as a speaker.

Piezoelectricity is the transformation of pressure (physical deformation) into electricity, discovered by the Currie brothers in 1880. On the contrary, when the electricity is applied to both sides of the material, it is the piezoelectric phenomenon that the film speaker uses this principle to make the sound by vibrating the film by sending electricity to both sides of the thin piezoelectric plastic film. Serve In order for the film speaker to work fully, it is necessary to attach electrode materials such as metal or oxide conductors to allow electricity to flow on both sides of the piezoelectric plastic. Polymeric materials, such as piezoelectric films, have the property of hydrophobicity, which makes it difficult to attach the electrode material on the film due to hydrophobicity.

1 is a front view of a film type speaker according to the prior art.

As shown in FIG. 1, the film-type speaker according to the related art has a piezoelectric polymer sheet 100 and a piezoelectric polymer sheet coated on both surfaces of the piezoelectric polymer sheet 100 and the piezoelectric polymer sheet 100 that generate mechanical vibrations due to voltage. 100) copper wire tape electrodes 104 and copper wire tape terminals 106 formed on one side of each polymer conductor film 102 coated on both surfaces thereof.

Therefore, when the output voltage is supplied to the terminal 106 formed of copper wire tape, the copper wire electrode 104 supplies the output voltage to the polymer conductor film 102, and the voltage difference is caused by the potential difference between the polymer conductor films 102. In response to the voltage, the piezoelectric polymer sheet 100 vibrates to generate unique sound.

However, the piezoelectric polymer sheet 100 of the film type speaker according to the related art having such a configuration is difficult to form the polymer conductor film 102 by applying a conductive polymer to the piezoelectric polymer sheet 100 due to its chemical properties. there was.

In addition, since the conductive polymer is not evenly applied, a non-uniform polymer conductor film 102 is formed, and thus the output of the film-type speaker is not constant, and there is a problem that a certain level of sound quality is not guaranteed.

As a surface modification method of a piezoelectric polymer sheet, Patent No. 0327557, "Acoustic device including a piezoelectric polymer speaker," has a predetermined shape of a polymer sheet surface-treated by an ion assist reaction method under vacuum, and conductive coating applied to both surfaces of the polymer sheet. Disclosed is an acoustic apparatus including a piezoelectric polymer speaker comprising an electrode composed of a polymer film, a terminal for applying an amplified external sound source signal to the electrode, and a piezoelectric polymer speaker that emits sound by causing mechanical vibration of the polymer sheet.

According to the above invention, the surface modification of the polymer material should be performed by using an ion assisted reaction method. The reactive gas selected from oxygen, nitrogen, hydrogen, ammonia, carbon monoxide, and a mixture thereof under vacuum is polycarbonate, poly Irradiation selected from argon, oxygen, air, krypton and mixtures thereof, while blowing directly onto the surface of the polymer including methyl acrylate, polyamide, teflon, PVDF, polyethylene terephthalate, polyethylene, polyolefin resins and silicone rubber The amount of 1 × 10 ¹⁴ to 5 × 10 ¹⁷ ions / cm 3, ion particles having an energy in the range of 0.5 KeV to 2.5 KeV are irradiated onto the surface of the polymer, and the contact surface of the polymer surface is reduced or the adhesion is increased. As a reforming method, an ion assisted reaction method is used.

However, in order to modify the surface of the polymer by such an ionic reaction method, not only the process must be performed in a vacuum state but also the problem that the polymer sheet is unnecessarily lost due to cutting the length of the polymer due to the limitation of the space to be in a vacuum state. There is.

It is an object of the present invention to provide a piezoelectric polymer speaker in which a conductive polymer film is formed on both surfaces of a polymer sheet without modifying the surface of the polymer sheet.

In order to achieve the above object, the present invention provides a piezoelectric polymer film having a predetermined shape; a polymer conductor film which is applied by mixing with a binder on both sides of the piezoelectric polymer film and supplies power to the piezoelectric polymer film; Electrodes extending along edges of the polymer conductor films; And it provides a piezoelectric polymer speaker comprising a terminal extending from the respective electrodes to the outside of each of the polymer conductor film.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment for.

2 is a front view of a film type speaker using a corona method according to an embodiment of the present invention.

With reference to the accompanying drawings will be described in detail a film-type speaker using a corona method according to an embodiment of the present invention.

As shown in FIG. 2, the film type speaker using the corona method according to the preferred embodiment of the present invention includes a piezoelectric polymer film 200, a polymer conductor film 202, an electrode 204, and a terminal 206. can do.

In addition, the film type speaker using a corona method according to an embodiment of the present invention may further include a reinforcing tape (208).

The piezoelectric polymer film 200 is mechanically vibrated according to the input voltage to output a sound corresponding to the voltage.

The piezoelectric polymer film 200 uses a reverse piezoelectric phenomenon of a piezoelectric element. The reverse piezoelectric phenomenon is a plate that is periodically stretched when a high frequency voltage is applied to a crystal plate having piezoelectricity. In particular, when the frequency of the voltage is matched to the natural frequency of the plate, the plate is resonated. It is a phenomenon that sound is generated due to strong vibration.

In the present invention, a polyvinyl fluoride (PVDF) film is used as the piezoelectric polymer film 200. However, it will be apparent to those skilled in the art that various piezoelectric polymer films may be used.

In the piezoelectric polymer speaker, the polymer sheet may be formed by selecting from a group consisting of a polymer mixture containing PVDF (polyvinylidenfluoride), a derivative thereof, an additive such as HEP, and a copolymer such as VDF / TrFE (Vinylidenfluoride / Trifluoroethylene). Can be.

The piezoelectric plate deforms itself by applying electricity. On the contrary, when pressure is applied to the piezoelectric plate, current is generated. The core material of the film speaker is none other than the polymer piezoelectric film called PVDF (Poly Vinyli Dene Fluoride). PVDF has a melting point of 170-185 ℃ and a continuous working temperature of 120 ℃, which is the lowest among insoluble resins, but it has injection molding, extrusion molding and other processability, and has excellent mechanical properties, weather resistance, and piezoelectricity. PVDF sheet type or PVDF film is the most commercialized among polarized polymers and has excellent piezoelectric and pyroelectric properties.

On both sides of the polymer sheet, a conductive polymer film is formed. The conductive polymer film is a group consisting of conductive polymers such as polyaniline, polythiophene, poly (3,4-ethylene dioxythiophene), polypyrrole, and polyphenylenevinylene (PPV), derivatives thereof, and organic conductors. It is formed by selecting from. By combining such conductive polymers in various ways, or by adding a certain resistive material in addition to the conductive polymer, the resistance value of the polymer conductor film 202 may be variously changed.

The binder makes the conductive filler closely adhered to the adherend and at the same time connects the filler in a chain form to show conductivity, and plays a role of conferring physical and chemical stability of the conductive coating film. Polymer materials such as polyurethane-based, silicone-based, polyimide-based, phenol-based, polyester-based, low melting point glass, and the like are used. In addition, it is composed of a suitable solvent, additives and the like to improve the workability of the adhesive, the dispersibility of the conductive filler. On the other hand, the following properties are required for the conductive adhesive.

1) Storage stability and pot life

More than 3 months should be stable without deterioration such as viscosity increase. In the case of separate forms from the main and the hardener, a pot life of at least 8 hours after mixing is required. Since the conductive adhesive is a paste liquid as a composite material of the resin and the conductive filler, it should be as small as possible to settle and separate the conductive filler.

2) Workability

Since the conductive adhesive is usually applied using a micro dispenser, the discharge amount from the needle should be constant and not flow down. In addition, the viscosity change with temperature or time should be small. In addition, when used in the screen printing method, good printability is required, and care should be taken in the dryness and mixing of bubbles on the screen.

3) Curing condition

It is ideal to cure at low temperature and in a short time. However, since the reaction rate of the adhesive is proportional to temperature, it is slightly longer at low temperatures and very short at high temperatures. In the case of curing in the open state, the one-component type is 30-60 minutes at 150 ° C and the two-component type is about 20-40 minutes at 130 ° C. In recent years, curing at about 200 ° C. for several tens of seconds has also become possible.

4) conductive

It is preferable that the volume specific resistance is as low as possible, but ρ = 5X10 -4Ω · cm or less is preferable.

5) Adhesive strength

The adhesive strength is preferably at least 30 kg / cm 3. In addition, if it is necessary to apply heat in post processing, there should be no deterioration in adhesive strength.

6) impurities

In fields with severe electrical characteristics, impurity ions such as halogen alkali metal ions should be suppressed as much as possible.

7) Stability over time

The adhesive cures under a certain condition and then gradually hardens when a heat history is applied. Therefore, deterioration does not occur over time even after curing. The cause of deterioration is the contact failure due to the oxidation of the conductive filler and the resin binder and the difference in volume expansion rate. The volume intrinsic resistance tends to be lowered in the case of silver-based adhesives, and in the case of adhesive strengths, under normal environmental test conditions, the curing proceeds by heat, resulting in an increase in adhesive strength.

On the other hand, the piezoelectric polymer speaker according to the present invention in the formation of the conductive polymer film on both sides of the piezoelectric polymer (especially PVDF) sheet without modifying the surface of the polymer sheet in the group consisting of the conductive polymer and its derivatives and organic conductors, etc. The binder is mixed with the selected material to form a film on the polymer sheet.

As a binder to be mixed with the conductive polymer material, physical properties such as adhesive strength may be controlled by using a binder including the following functional group according to the base film. At least one selected from the group containing at least one functional group such as acryl, urethane, epoxy, amide, imide, ester, carboxyl, and hydroxyl group is used as the binder. Conductive adhesive resins include epoxy resins, polyester resins, acrylic resins, polyimide resins, polysulfone epoxy resins, phenol resins, melamine resins, polyimide resin fillers silver, copper, gold, palladium, silver-palladium alloys, carbon, nickel Other Solvent Additives Curing Agent Additives Currently, conductive resin materials include conductive adhesives (ECAs), anisotropic conductive films (ACFs) and anisotropic conductive pastes (ACPs), all of which are organic polymer compounds. Conductive fine particles were dispersed by using water as a matrix. Changing the compounding ratio of the anisotropic material matrix and the conductive filler changes the specific resistance of the cured product. Slowly reducing the conductive filler results in anisotropic conductivity. As for the principle that the conductive adhesive expresses conductivity, the conductive filler dispersed in the adhesive is brought into contact with the filler in the curing or solidifying step to express the conductivity. The conductive adhesive can be classified into room temperature drying type, room temperature curing type, thermosetting type, high temperature baking type, UV curing type and others. The room temperature drying type uses a thermoplastic resin such as acrylic, contains a solvent, and the room temperature curing type uses a two-component, highly reactive curing agent. As the conductive filler, metal powders such as gold, platinum, silver, copper, nickel, carbon or carbon fiber, graphite, composite powder, and the like are used. As the binder, polymer materials such as epoxy, polyurethane, silicone, polyimide, phenol, polyester, and low melting glass are used. In the thermosetting conductive adhesive, epoxy is mainly used as a binder, and workability and stability can be improved by mixing or microencapsulating polyparabanic acid or bismaleimide resin. As a property required for conductive adhesives, storage stability and pot life of 3 months or more should be stable without deterioration such as viscosity increase. In the case of separate forms of main and hardeners, a pot life of at least 8 hours after mixing is required. Since the conductive adhesive is a paste liquid as a composite material of the resin and the conductive filler, it should be as small as possible to settle and separate the conductive filler, and the viscosity change with temperature or time should be small. In addition, when used in the screen printing method, good printability is required, and care should be taken in the dryness and mixing of bubbles on the screen.

In order to form a conductive polymer film on both surfaces of the piezoelectric polymer, a conductive polymer material mixed with a binder is applied to the piezoelectric polymer sheet and dried. Ideally, the binder is cured at a low temperature and in a short time. However, since the reaction rate of the adhesive is proportional to temperature, it is slightly longer at low temperatures and very short at high temperatures. In the case of curing in the open state, the one-component type is 30-60 minutes at 150 ° C and the two-component type is about 20-40 minutes at 130 ° C. In recent years, curing at about 200 ° C. for several tens of seconds has also become possible. It is preferable that the conductive volume resistivity is as low as possible, but ρ = 5X10 -4? Cm or less is preferable. Adhesive Strength The adhesive strength is preferably at least 30 kg / cm 3. In addition, if it is necessary to apply heat in post processing, there should be no deterioration in adhesive strength.

Silicone-based conductive adhesives Silicone adhesives are made of siloxane bonds (Si-O-Si) with a silicon-oxygen bond as a backbone, and unlike general organic resins with a carbon-carbon bond as a backbone, they are particularly resistant to heat and cold resistance. It is an excellent adhesive, exhibits stable properties over a wide range of temperatures, and has excellent weather resistance, electrical properties, and chemical resistance. BACKGROUND ART In recent years, with the high-density packaging represented by high-performance, high-integration, high-speed, and surface-mounting of semiconductor devices, semiconductor devices have become larger and the amount of heat generated by their operation has also increased. Due to differences in thermal expansion coefficients of various constituent materials, various problems arise in semiconductor devices or electronic components due to thermal stresses between dissimilar materials generated during mounting processes or during operation, and there is an increasing demand for materials that relieve stress. Silicone elastomers are widely used in this application because of their low Young's modulus, their properties as stress relieving materials, and the combination of various curing systems. The conductive adhesive is composed of three components: conductive particles, resin, and solvent.In terms of reliability and ease of handling, conductive powders include metal powders such as silver powder, copper powder, and nickel powder. In addition to adhesion, the particles are connected in a chain and exhibit conductivity, and polymer materials such as epoxy resins, polyurethanes, silicones, polyimides, phenols, polyesters, and glass are used depending on the purpose of use and required properties. In addition, it is composed of a suitable solvent, additives and the like to improve the workability of the adhesive and the dispersibility of the conductive particles. As the form of the silicone adhesive, one-liquid paste and solid (sheet) hot melt type (reactive, non-reactive) and the like are used. The curing system varies depending on the binder, and is classified into a thermosetting type, a thermoplastic type, and a room temperature type. In addition, there are an anaerobic type and a moisture type.

Epoxy Conductive Adhesives Conductive adhesives include room temperature drying type, room temperature curing type, thermosetting type, high temperature firing type, UV curing type, and the like.At room temperature drying type, a thermoplastic resin such as acrylic type is used, and a solvent is included. The highly reactive hardening agent is used. The thermosetting type | mold uses thermosetting resins, such as an epoxy, a phenol, and a polyimide, as a binder, and there are two types of 1-component type and 2-component type. As the conductive filler, metal powders such as gold, platinum, silver, copper, nickel, carbon or carbon fiber, graphite, composite powder, and the like are used. In thermosetting conductive adhesives, epoxy-based binders are the mainstream, and workability and stability are improved by mixing or microencapsulating polyparabanic acid and bismaleimide resin. Epoxy-based conductive adhesives need to mix at least 70% silver powder in epoxy resin, and exhibit a conductivity of 10-4? Cm. On the other hand, the one-component solvent-free conductive adhesive using an epoxy resin as a binder was developed to prevent the conductive property from deteriorating in a high temperature and high humidity environment, and the conductivity change is very small in a high temperature and high humidity environment. Curing conditions are 110 degreeC / 30 minutes -150 degreeC or more / 5-10 minutes. ③ There is no change of contact resistance in long-term thermal shock test or high temperature (150 ℃) standing test.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example

It is PVDF produced by KF Piezo of Kureha, Japan, and its thickness is 30um. The PVDF sheet (film) was placed on a flat surface, fixed to a frame made of metal to prevent the sheet from moving, and the frame could be fixed using a vacuum inlet. PEDOT (poly (3,4-ethylenedioxythiophene)) was used as the conductive polymer material. 95% by weight of epoxy is mixed with a binder in 5% by weight of PEDOT to control physical properties such as adhesion. After fixing the silk screen on the fixed sheet, about 40 cc of the conductive polymer solution mixed with the binder was injected. The silk screen was used to control the thickness of the electrode layer of the polymer using that the diameter of the fibers used in the mesh is about 100 μm. After injection of the solution, the solution was applied to the entire surface using a squeeze (squeez). The screen was detached at time intervals with the squeeze passing through the front two or more times to avoid partial drying. After detaching the silk screen, the coating mold was moved to a drying place so as not to change the thickness of the electrode by tilting, and then dried.

In the present invention, the polymer conductor film 202 is formed on both surfaces of the piezoelectric polymer film 200 to supply voltage to the piezoelectric polymer film 200. Since it is made of a conductive polymer, a voltage applied from the outside can be evenly supplied to the entire piezoelectric polymer film 200. Two polymer conductor films 202 are formed on one piezoelectric polymer film 200, and one polymer conductor film 202 is connected to the anode of the power source and the other polymer conductor film 202 is connected to the cathode of the power source. The potential difference is formed on both sides of the piezoelectric polymer film 200 to supply voltage.

More preferably, the polymer conductor film 202 according to the present invention may be formed spaced apart from the edge of the piezoelectric polymer film 200 by a predetermined distance.

That is, the piezoelectric polymer film 200, in which the polymer conductor film 202 is not formed, is applied to the piezoelectric polymer film 202 by applying the conductive polymer at a predetermined distance away from the edge of the piezoelectric polymer film 200. The polymer conductor film 202 is formed to surround the slope of the polymer film 200.

When the polymer conductor film 202 is formed in this manner, the piezoelectric polymer film 200 on which the polymer conductor film 202 is formed is vibrated by the voltage to be formed, but the piezoelectric polymer film on which the polymer conductor film 202 is not formed is formed. 200 does not vibrate because no voltage is supplied.

Therefore, the piezoelectric polymer film 200 in which the polymer conductor film 202 is not formed acts as an edge of the piezoelectric polymer film 200 in which the polymer conductor film 202 is vibrated, so that the negative piezoelectric polymer film 200 This can be prevented from breaking at the edge of the frame.

In addition, the polymer conductor film 202 according to the preferred embodiment of the present invention may be configured to have a specific resistance value in the range of 20Ω ~ 2,000Ω.

Typically, the polymer conductor film 202 is composed of a conductive polymer such as polyaniline polythiophene, PEDOT, polypyrrole, PPV, etc., by combining these conductive polymers in various ways, or by adding a certain resistive material in addition to the conductive polymer, The resistance value of 202 can be variously changed.

The polymer conductor film 202 is formed by coating a conductive polymer solution mixed with a conductive polymer and an adhesive binder in a predetermined ratio according to a required resistance value on a base film, wherein the conductive polymer solution is 0.5 to 50 parts by weight of the conductive polymer, It consists of 10 to 30 parts by weight of the adhesive binder and 20 to 89.5 parts by weight of the solvent.

In this case, the binder serves to improve adhesion and adhesion between the base film and the polymer conductor film, and the binder includes at least one functional group selected from acryl, urethane, ether, ester, epoxy, amide, imide, and the like.

In addition, the solvent is methyl alcohol, ethyl alcohol, isopropyl alcohol, normal butanol, water, toluene, xylene, 1-methyl-2-pyrrolidinone, chloroform, ethyl acetate, 2-methoxyethanol, ethylene glycol, polyethylene glycol , One kind selected from dimethyl sulfoxide, or two or more kinds of the above solvents may be mixed and used. In particular, when the conductive polymer solution is prepared using a solvent such as ethylene glycol, polyethylene glycol, or dimethyl sulfoxide, the resistance value of the conductive polymer can be lowered, which is effective.

In addition, the conductive polymer solution may be used by mixing a certain amount of metal powder, carbon black or carbon nanotubes in order to lower the resistance value.

Frequency-specific sound pressure characteristics according to the resistance value change of the polymer conductor film 202 will be described in detail later with reference to FIG. 4.

The electrode 204 is formed to extend along the edge of each polymer conductor film 202 to supply power to the polymer conductor film 202.

More preferably, the electrode 204 according to the present invention is formed by printing a silver paste or a conductive mixed ink along the edge of the polymer conductor film 202.

Typically, the electrode of the film-type speaker is configured using a copper wire tape, but as described above, since the copper wire tape is not completely adhered to the conductive polymer film, there is a problem in that a short circuit occurs at the contact portion between the copper wire tape electrode and the conductive polymer film.

In the present invention, in order to solve this problem, the electrode 204 to the polymer conductor film 202 by printing a silver paste or conductive mixed ink containing silver having a higher conductivity than copper to the polymer conductor film 202 using nanotechnology. It is formed in close contact with the.

The terminal 206 extends from the electrode 204 to the outside of the polymer conductor film 202 and is connected to an external power supply to supply a voltage to the polymer conductor film 202 through the electrode 204.

The terminal 206 according to the present invention may be formed at approximately the center of the electrode 204 or at the corner of the electrode 204.

In addition, according to an exemplary embodiment of the present invention, the film type speaker further includes a reinforcing tape 208 formed on one side of the terminal 206 to support the terminal 206 and to insulate one side of the terminal 206. can do.

Since the terminal 206 extends to the outside of the polymer conductor film 202, both sides of the terminal 206 are conductive, so that one side of the terminal may be insulated to prevent short circuits or short circuits. Attaching reinforcing tape 208.

In addition, the reinforcing tape 208 supports the terminal so that the shape of the terminal 206 is not deformed.

3 is a graph showing sound pressure for each frequency according to the resistance value of the polymer conductor film of the piezoelectric polymer speaker according to the exemplary embodiment of the present invention.

Referring to Figure 3 in more detail, when the resistance of the polymer conductor film 202 is 60Ω, 100Ω, 400Ω, 800Ω, 1500Ω, respectively, it is a graph showing the sound pressure for each frequency output from the film-type speaker according to the present invention.

With reference to the accompanying Figure 3 will be described in detail with respect to the frequency-specific sound pressure characteristics according to the resistance value change of the film-type speaker using a corona method according to an embodiment of the present invention.

In general, when the sound pressure output from the speaker is about 82db, it is possible to provide a good sound quality to the user.

Therefore, as shown in Fig. 3, when the resistance value of the polymer conductor film 202 according to the present invention is selected to any value within the range of 60Ω or more and 1500Ω or less, the film type speaker according to the present invention has a constant level of sound pressure. (I.e., sound output characteristics that can be used as a speaker).

Therefore, the resistance value of the polymer conductor film 202 can be adjusted to show good output characteristics in an appropriate frequency band according to the use of the film type speaker (low band, mid band, high band, etc.).

That is, when the output characteristics of the 800Hz to 2,000Hz band are to be enhanced, the conductive polymer and the resistive material constituting the polymer conductor film 202 such that the resistance value of the polymer conductor film 202 falls within a range of 400Ω to 1500Ω. Will be combined.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes and additions within the spirit and scope of the present invention. Additions should be considered to be within the scope of the following claims.

The piezoelectric polymer speaker according to the present invention forms a film directly on both sides of the sheet by mixing a binder with a conductive polymer material without modifying the surface of the piezoelectric polymer sheet, so that the process is not only simple and does not require a separate working environment. There is a convenient advantage to work in the air at room temperature, there is an advantage of minimizing the loss of the piezoelectric polymer sheet because the conductive polymer film can be formed without cutting the piezoelectric polymer sheet.

Claims (4)

Piezoelectric polymer films of a predetermined shape; A polymer conductor film which is applied to both surfaces of the piezoelectric polymer film by mixing with a binder and supplies power to the piezoelectric polymer film; Electrodes extending along edges of the polymer conductor films; And And a terminal extending from the electrodes to the outside of each of the polymer conductor films. The method of claim 1, The binder includes at least one functional group such as acryl, urethane, epoxy, amide, imide, ester, carboxyl, hydroxyl, and the like. The method of claim 1, The polymer conductor film is a film-type speaker using a corona method, characterized in that formed spaced apart a predetermined distance inward from the edge of the piezoelectric polymer film. The method of claim 1, The resistance value of the polymer conductor film is a film-type speaker using a corona method, characterized in that it has a predetermined resistance value in the range of 50Ω or more and 100Ω.

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