KR20050100852A - A vibration plate of micro-speaker - Google Patents

Abstract

The present invention relates to a micro speaker diaphragm for an electro-acoustic transducer,

Depositing a highly rigid thin film 200 in the center of the surface of the base plate 100,

Consists of the central portion 150 and the peripheral portion 160 surrounding the central portion 150, the thickness of the central portion 150 is thicker than the peripheral portion 160, or locally mechanical stiffness by using a material of high rigidity By

It can cope with sound pressure increase of speaker and improve efficiency, and can realize high quality original sound reproduction and sound smoothly in all frequency bands.

Description

Vibration plate of micro speaker {A VIBRATION PLATE OF MICRO-SPEAKER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm of a micro speaker, and more particularly, to a diaphragm of a micro speaker configured to reinforce sound pressure in the mid-low range.

In the case of the micro-speaker for the electro-acoustic transducer, a single speaker diaphragm is employed because it is impossible to use a speaker that implements multiple sound ranges due to application characteristics such as its size.

As shown in Fig. 1, the diaphragm 1 of a general micro speaker is dish-shaped (circle, square, etc.), and portions contributing to various sound bands vary depending on the position. That is, during the vibration, the outermost part mainly contributes to the bass part, the center part to the treble part, and the boundary mainly contributes to the bass part. In order to effectively improve sound quality, it is necessary to overcome a drop in sound pressure in each vibration range vibration mode. As the material of the speaker diaphragm, a polymer such as polyetherimide (PEI), polyethylene26-Naphthalate (PEN), or a metal such as titanium (Ti) is mainly used. However, diaphragms composed of other polymers or metallic materials are also disclosed.

Using a single diaphragm made of this material avoids the disadvantages of tonal splitting and severely axial frequency response. However, since the rigidity of the material itself is small, and size and structural constraints are imposed, it is difficult to implement sound of the entire band. In particular, the conventional micro speaker having a single speaker diaphragm has a disadvantage in that the sound pressure of the bass portion is significantly lowered. In addition, when titanium foil is used as a unit, the sound may be split in the high range.

In order to overcome this problem, a diaphragm having a rigidity and a very thin thickness of about several μm should be used. However, in this case, it is difficult to realize a high output and has limitations in application due to economic and moldability disadvantages.

In addition, when the material of the diaphragm is made of an oxide-based or carbide-based ceramic, the diaphragm can be adopted as an excellent diaphragm material because it has twice as high rigidity as a metal such as aluminum (Al) or titanium (Ti). However, since the physical properties of the material itself is weak, there is a problem that it is difficult to manufacture a single product in the form of a thin diaphragm.

Moreover, in the case of a diamond material, there is a disadvantage in that the manufacturing cost is high and the productivity is greatly reduced, making commercial applications difficult.

As a result of various studies, the present inventors have found that by increasing the stiffness of a certain portion of the diaphragm, the sound pressure in the range generated in the portion can be reinforced.

Accordingly, an object of the present invention is to provide a diaphragm of a micro speaker that enhances the sound pressure in the mid-low range and improves efficiency by changing the mode in the mid-low range by increasing the stiffness of a predetermined portion of the diaphragm.

In order to achieve the above object,

The diaphragm of the micro-speaker for an electro-acoustic transducer according to the present invention is characterized in that a highly rigid thin film is formed on the center of the surface of the base plate.

Here, the base plate may be a polymer plate.

Alternatively, the base plate may be a metal plate.

The deposited highly rigid thin film may be composed of a single thin film of metal. At this time, the deposited metal may be any one of Ti, Cr, Al, Cu, Ag.

Instead, the deposited highly rigid thin film may be composed of a single thin film of metal nitride. The metal nitride may be TiN or CrN.

Alternatively, the deposited highly rigid thin film may be composed of a single thin film of ceramic. The ceramic may be any one of SiO ₂ , TiO ₂ , Al ₂ O _{3, and} WC.

In addition, the deposited highly rigid thin film may be composed of a multilayer film of metal nitride / metal nitride.

In addition, the deposited highly rigid thin film may be composed of a multi-layer thin film of metal nitride / ceramic.

In addition, the deposited highly rigid thin film may be composed of a multilayer thin film of ceramic / ceramic.

In addition, the deposited highly rigid thin film may be a superlattice nanostructured multilayer thin film.

At this time, it is preferable that the superlattice nanostructured multilayer thin film is a multilayer thin film in which WC and TiAlN are laminated.

In addition, the deposited highly rigid thin film may be a nanostructured thin film containing a small amount of metal in the transition metal.

In this case, the nanostructured thin film in which a trace amount of metal is put in the transition metal may be composed of Ti-Metal-N or Cr-Metal-N.

On the other hand, it is preferable that a bonding layer is interposed between the highly rigid thin film and the base plate.

In addition, it is preferable that a bonding layer is also interposed between the multilayer thin films.

In addition, another micro-speaker diaphragm for an electro-acoustic transducer according to the present invention,

It consists of a center part and the peripheral part which surrounds this center part, and is made from the same material as the said center part,

It is characterized in that the thickness of the central portion is formed larger than the thickness of the peripheral portion.

In addition, another micro-speaker diaphragm for an electro-acoustic transducer according to the present invention,

A periphery with a hole formed in the center and a material having the same thickness as the periphery and having a greater rigidity than the periphery, and characterized by comprising a center portion filled in the periphery of the periphery.

By such a configuration, the principle of reinforcing the sound pressure of the portion by increasing the rigidity of the central portion of the diaphragm constituting the speaker is as follows.

The diaphragm of the speaker is installed under the diaphragm and vibrates by a force formed by an electromagnet in which a coil is wound, and an interaction with a permanent magnet thereunder. At this time, the force depends on the mass of the diaphragm, the damping coefficient, the stiffness coefficient, of which damping and stiffness is greatly affected by the elastic modulus. Therefore, when the elastic modulus is locally changed, the acoustic characteristics are changed through the change of the vibration mode of the diaphragm. It is a central principle of the present invention to reinforce the sound pressure of the bass by locally increasing the elastic modulus value using this principle.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

2 and 3 show the diaphragm structure of the micro speaker for the electro-acoustic transducer according to the present embodiment.

As shown, the diaphragm is dish-shaped (round, square, etc.). In addition, the high hardness material 200 is deposited by coating on the central portion of the corn portion.

As described above, the high hardness coating formed at the center portion increases rigidity and mass at the center portion of the micro speaker diaphragm, and thus, high power can be obtained by reinforcing the sound pressure in the bass band generated at this portion. The region of the central portion is a portion that generates the mid-low range, and since the area may vary depending on the material and the size, it is difficult to precisely define it, and it can only be determined empirically through experiments. In addition, it is difficult to clearly define the high hardness coating thickness as it depends on the type of base plate, but once deposition is performed, the reinforcing effect of sound pressure appeared, and the thickness does not affect the vibration of the circumferential part of the center part. Just do it.

As a method of coating with a high hardness material in the center, a method by low temperature magnetron sputtering is suitable among plasma deposition methods. This is because the permanent magnet is mounted on the cathode to apply a magnetic field in a direction parallel to the target surface to focus electrons at a high density and to rotate the electrons around them, and supply a sputtering gas such as argon (Ar) to supply the electrons. After colliding with the gas, the dissociated gas collides with the target to generate atoms or ions from the target, and is deposited on the vapor deposition material (vibration plate). In particular, the low temperature plasma deposition method is used because the diaphragm has a very thin and complicated shape, and thus the process must be performed at a temperature of 100 ° C. or lower.

Figure 7 shows the structure of a typical magnetron sputtering device (coating device of high hardness material) for producing a diaphragm of a micro speaker according to the present invention.

As shown, the magnetron sputtering apparatus 700 is a vacuum vessel 710, the coating treatment is performed, the evacuation chamber 720 for charging and evacuating the deposition material 770, the exhaust after coating to obtain a product A vacuum magnet 730 for exhaust, and a magnetron source 744 equipped with a target made of a material such as Ti or Cr, as a dual magnetron system 740 for forming a high hardness thin film, and Cu as an additive element Magnetron source 745 equipped with a target, Ag, etc., a vacuum pump 760 capable of dropping the pressure of the vacuum vessel below 1 × 10 ^-5 Torr, and adjusting the flow rate of nitrogen or argon gas for compound synthesis It consists of a gas flow rate control unit 790, and a specimen support 780 to form a uniform thin film through the left and right movement.

2 and 3 show the configuration of a high efficiency diaphragm for a micro speaker obtained by the coating apparatus 700 described above.

As shown, it is composed of a base plate (coated material) 100 in the form of polymer and metal thin films, a bonding layer 300 for adhesion, and a highly rigid thin film 200 formed through a deposition process, the thickness of which is Can range from several hundred nm to several microns, depending on the substrate. The bonding layer 300 is a portion for compensating for the inferior adhesion due to the difference in material properties or the lattice structure between materials between the base plate 100 and the high rigidity thin film 200. For example, when the base plate 100 is made of a polymer, since the polymer is a carbon-based organic material, it is not easily attached to other materials such as metal. Therefore, as a method of increasing the adhesion, there is a method of inserting a matrix material existing in the high rigidity thin film 200 as the bonding layer 300 as a material that reacts well with the polymer.

In the present embodiment, the base plate 100 is made of Ti, the bonding layer 300 is made of TiN, and the high rigid film 200 is made of Ti-M (metal) -N nanostructured thin film. have. Of course, in the case where TiN is deposited only on Ti to increase rigidity, there may be no bonding layer.

As another example, when coating copper (Cu) on the polymer, it is preferable to first coat a bonding layer such as Cr and Ni.

In addition, there is also a method of increasing the adhesion between the base plate 100 and the high rigidity thin film 200 through plasma cleaning.

As shown in FIG. 4, examples of the highly rigid thin film 200 include a single element of a metal, or a trace element added to a ceramic single thin film 214, a multilayer thin film 215, and a hard thin film such as an oxide or a nitride. As a result, a new nanostructured multilayer thin film 216 or the like that can not be obtained by single layer coating can be obtained. In addition, it is possible to locally coat a predetermined portion (center portion) through a simple mask process.

The single thin film 214 of the metal may be formed of a thin film of Ti, Cr, Al, Cu, Ag, or the like.

In addition, the ceramic single thin film 214 may be formed of a single thin film of a metal nitride such as TiN or CrN, or a thin film of SiO ₂ , TiO ₂ , Al ₂ O _3, WC, or the like.

In addition, the multilayer thin film 215 may be formed of a multilayer thin film of metal nitride and metal nitride, or a multilayer thin film of metal nitride and ceramic, or a multilayer thin film of ceramic and ceramic.

The nanostructure thin film 216 may be a superhard nanostructure thin film such as a superlattice nanostructured multilayer thin film in which WC and TiAlN are stacked, or a nanostructured thin film made of Ti-Me-N material containing a small amount of metal in a transition metal. It may be configured.

The ultrahard nanostructure thin film refers to a thin film having a structure in which the density of grain boundaries and the density of grains are increased. In general, when a stress is generated in a metal, grain boundaries are slipped, and deformation of the stress occurs. When the nanostructure is formed, such a slip mechanism is resisted by grains to form an ultra-high hardness thin film having a much higher hardness.

Superlattice nanostructure refers to a thin film structure in which the nanostructure is made of a multi-layered interlayer structure instead of the addition of micrometals.

As an example of a nanostructured thin film containing a small amount of metal in a transition metal, a metal element capable of forming an intermetallic compound on a state diagram such as Ag, Cu, or Si is added to a transition metal such as Ti-N or Cr-N. It can be mentioned.

On the other hand, if the above-mentioned bonding layer 300 is interposed between the high rigidity thin film 200 and the base plate 100 or between the multi-layered high rigidity thin film 200, adhesion may be enhanced.

On the other hand, using the same material consisting of the polymer plate or metal plate, etc., the thickness of the central portion 150 is configured to be larger than the thickness of the peripheral portion 160, it is possible to reinforce the sound pressure of this portion by increasing the rigidity of the central portion. The diaphragm 1000 based on this is shown in FIG. 5.

In addition, the diaphragm is composed of a polymer plate or a metal plate and formed of a periphery portion 160 having a central hole, and a central portion 150 composed of a material having greater rigidity than the periphery portion 160 and filled in the hole of the periphery portion 160. By using 1000, the sound pressure in the mid-low range can also be reinforced. In this case, it is necessary to make the coupling between dissimilar metals solid through a special mold design in the manufacture of the diaphragm. The structure of the diaphragm 1000 based on this is shown in FIG.

Hereinafter, an experimental example of reinforcing the high pressure thin film 200 on the surface of the base plate 100 to reinforce the sound pressure in the mid-low range will be described.

Experimental Example

FIG. 5 is a device constituting the present experimental example, and shows a device for implementing a low temperature magnetron sputtering method in which a process is performed at 100 ° C. or lower (less than the melting point of a polymer) of plasma deposition. By using this apparatus, not only the formation of a high hardness single film but also the formation of an ultra high hardness thin film such as a multilayer structure thin film and a nano structure thin film can be performed.

First, in order to reinforce the sound pressure of the mid-low band, the position is formed to form a high hardness thin film through deposition on the central portion of the diaphragm. In the present Example, the space | interval between a target and a diaphragm was 10 cm.

The size of the base plate was Φ15mm and varied, and the shape was circular.

After evacuating the vacuum vessel to 2 x 10 ^-5 Torr, argon gas is introduced and maintained at 3 x 10 ^-3 Torr.

The base plate made of polymer (PEI) is fixed to a specimen support on which a cooling device is mounted.

And, it was adjusted so that the deposition occurred in the center of the diaphragm corresponding to the central corn portion of the micro speaker.

In order to improve the adhesion between the base plate and the thin film to be deposited, pretreatment is performed by using plasma such as argon and oxygen plasma, corona discharge, or the like, and the first bonding layer is deposited. The first bonding layer is formed by depositing Ti under an argon gas atmosphere. The deposition thickness at this time is preferably about 10 to 50 nm.

Next, a second bonding layer composed of TiN is deposited on the first bonding layer.

In order to further synthesize ultrahard films, a nanostructured ultrahard film layer (Ti-Me-N) made by adding a trace amount of metal to Ti transition metal is deposited. The thickness of the thin film at this time is about 500-1000 nm (1 micrometer).

As a result, a structure of the first bonding layer / second bonding layer / ultra high hardness thin film layer is formed on the base plate made of a polymer.

As a result of applying the high-efficiency micro diaphragm of the present invention to the speaker, by increasing the sound pressure of the mid and low range by about 4dB, the output could be increased by about 2.5 times, the sound quality was very smooth, high sensitivity and sound close to nature. You can play it.

According to the present invention having the above-described configuration, by locally strengthening the middle portion of the diaphragm for the micro-speaker through the plasma coating, it is possible not only to overcome the sound pressure drop in the mid and low bands, but also to realize a high output sound, in the high frequency range. This has the advantage that it is possible to compensate for the defect that the tone is split and the axial frequency response is severely deflected. Accordingly, high quality sound can be realized through a single micro speaker.

1 is a perspective view showing a diaphragm of a conventional micro speaker.

2 is a perspective view showing the structure of a diaphragm of a micro speaker according to an embodiment of the present invention.

3 is a cross-sectional view showing the structure of a diaphragm of a micro speaker according to an embodiment of the present invention.

4 is a view showing the internal structure of the vapor deposition portion, (a) shows a single thin film structure, (b) shows a multilayer structure, and (c) shows a nanostructure by addition of a trace amount of metal.

5 is a cross-sectional view showing the structure of a diaphragm of a micro speaker according to another embodiment of the present invention.

6 is a cross-sectional view showing the structure of a diaphragm of a micro speaker according to another embodiment of the present invention.

FIG. 7 is a structural diagram showing a magnetron sputtering apparatus for producing a diaphragm of the micro speaker of FIG. 2. FIG.

※ Explanation of Major Drawings

100 ... base plate

200 ... High Rigidity Sheet

300 ... bonding layer

700 ... Plasma Coating Equipment

Diaphragm of 1000 ... micro speaker

Claims (20)

In the micro speaker diaphragm for an electro-acoustic transducer, Diaphragm of the micro-speaker, characterized in that the high rigid film 200 is deposited on the center of the surface of the base plate (100). The method of claim 1, The base plate 100 is a diaphragm of the micro speaker, characterized in that the polymer plate. The method of claim 1, The base plate 100 is a diaphragm of the micro speaker, characterized in that the metal plate. The method of claim 1, The deposited high rigidity thin film 200 is a diaphragm of the micro speaker, characterized in that the single thin film of metal. The method of claim 1, The deposited high rigidity thin film 200 is a diaphragm of a micro speaker, characterized in that the single thin film of metal nitride. The method of claim 1, The deposited high rigidity thin film 200 is a diaphragm of a micro speaker, characterized in that the single thin film of ceramic. The method of claim 1, The deposited high rigidity thin film 200 is a diaphragm of the micro speaker, characterized in that the multilayer film of metal nitride / metal nitride. The method of claim 1, The deposited highly rigid thin film 200 is a diaphragm of the micro speaker, characterized in that the multilayer film of metal nitride / ceramic. The method of claim 1, The deposited high rigidity thin film 200 is a diaphragm of the micro speaker, characterized in that made of a multilayer ceramic / ceramic thin film. The method of claim 4, wherein The deposited metal is any one of Ti, Cr, Al, Cu, Ag, diaphragm of the micro speaker. The method of claim 5, The metal nitride is TiN or CrN diaphragm of the micro speaker. The method of claim 6, The ceramic is a diaphragm of a micro speaker, characterized in that any one of SiO ₂ , TiO ₂ , Al ₂ O _3, WC. The method of claim 1, The deposited high rigidity thin film 200 is a diaphragm of the micro speaker, characterized in that the superlattice nano structure multilayer thin film. The method of claim 13, The superlattice nanostructured multilayer thin film is a diaphragm of a micro speaker, characterized in that the multilayer thin film laminated WC and TiAlN. The method of claim 1, The deposited highly rigid thin film 200 is a diaphragm of a micro speaker, characterized in that the nanostructured thin film in which a small amount of metal is put in the transition metal. The method of claim 15, The nanostructured thin film in which a trace amount of metal is put in the transition metal is composed of Ti-Metal-N or Cr-Metal-N. The method of claim 1, Diaphragm of the micro-speaker, characterized in that the bonding layer 300 is interposed between the highly rigid thin film 200 and the base plate (100). The method according to any one of claims 7 to 9 or 13, Diaphragm of the micro-speaker, characterized in that the bonding layer 300 is interposed between the multilayer thin film. In the micro speaker diaphragm for an electro-acoustic transducer, It consists of the center part 150 and the peripheral part 160 which surrounds this center part 150, and is made of the same material as the said center part 150, Diaphragm of the micro-speaker, characterized in that the thickness of the central portion 150 is formed larger than the thickness of the peripheral portion (160). In the micro speaker diaphragm for an electro-acoustic transducer, A central portion 150 having a hole formed in the center and a material having the same thickness as that of the peripheral portion 160 and having greater rigidity than the peripheral portion 160 and filled in the hole of the peripheral portion 160. The diaphragm of the micro speaker, characterized in that consisting of.