KR101830761B1 - Speaker using dynamic speaker and piezoelectric element - Google Patents

Abstract

A speaker according to the present invention includes: a yoke in which a receiving space is formed; a magnet which is arranged in the receiving space and includes a plate on an upper side thereof; a voice coil which is arranged between the yoke and the magnet; a diaphragm which is arranged on the upper side of the plate and to which the voice coil is fixed; a cap with which a piezoelectric element composed of a metal plate and a piezoelectric ceramic with a square shape boned on the upper side of the metal plate is integrated and which is provided on an opening part of the upper side of the yoke so that the piezoelectric element is arranged on the upper side of the diaphragm; and a sub metal plate with a square shape bonded in a position facing the piezoelectric ceramic, one the lower side of the metal plate. Accordingly, the present invention can prevent a hissing sound.

Description

[0001] The present invention relates to a speaker using a dynamic speaker and a piezoelectric element,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker, and more particularly, to a speaker capable of providing high quality sound using a dynamic speaker that implements a low-frequency sound and a piezoelectric element that implements a high-frequency sound.

Generally speaking, a speaker is an acoustic device that converts an electric signal into a vibration of a diaphragm to generate a small-sized wave in the air to radiate sound waves. The acoustic device may be a dynamic type, an electromagnetic type, an electrostatic type, Self-distortion type.

A dynamic type with relatively high performance is widely used for music reproduction and voice. The dynamic type uses a principle in which when a voice signal current is supplied to a voice coil in a magnetic field of a permanent magnet, a mechanical force acts on the voice coil to cause movement according to the intensity of the current.

However, such a dynamic type is suitable for realizing a low-frequency sound, but has a disadvantage that it is relatively weak to implement a high-frequency sound. A 2-way speaker or a 3-way speaker has been proposed to compensate for this problem, but the structure is complicated and expensive.

As a registered patent of the applicant of the present invention which solves this problem, there is a No. 10-1515815.

According to the above-mentioned patent, a piezoelectric speaker composed of a metal plate and a rectangular piezoelectric ceramics bonded to the upper surface thereof is disposed above the diaphragm on which the voice coil is fixed, thereby providing a dynamic speaker for realizing a low- It is possible to provide a high-quality sound with a simple structure.

On the other hand, due to the piezoelectric element, the sound pressure characteristic in which the sound pressure rises significantly in a part of the high-frequency range may cause a problem that the sound of the musical instrument or the voice may emerge as a rough sound or a chisel sound may occur.

Patent Registration No. 10-1515815 (Apr. 21, 2015)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a speaker in which a piezoelectric element composed of a metal plate and a rectangular piezoelectric ceramic bonded to an upper surface of the metal plate is disposed above a diaphragm to which a voice coil is fixed, And a speaker capable of suppressing a sound pressure characteristic and preventing a sound of a musical instrument or a voice from being outputted as a rough sound or from being chipped.

It is to be understood, however, that the technical scope of the present invention is not limited to the above-described technical problems, and other technical problems may be derived from the following description.

According to an aspect of the present invention, there is provided a speaker comprising: a yoke having a receiving space formed therein; A magnet disposed in the accommodation space and having a plate on an upper surface thereof; A voice coil disposed between the yoke and the magnet; A diaphragm disposed at an upper portion of the plate and to which the voice coil is fixed; A cap provided at an upper opening of the yoke so that the piezoelectric element is integrally coupled to a metal plate and a rectangular piezoelectric ceramic element bonded to the upper surface of the metal plate and the piezoelectric element is disposed above the diaphragm; And a rectangular sub-metal plate bonded to a lower surface of the metal plate at a position facing the piezoelectric ceramics.

The area of the sub metal plate is preferably smaller than the area of the piezoelectric ceramics.

It is preferable that the area of the sub metallic plate is 50% or more and less than 100% of the area of the piezoelectric ceramics.

The area of the sub metal plate is preferably 50% or more and 90% or less of the area of the piezoelectric ceramics.

According to another aspect of the present invention, there is provided a speaker comprising: a yoke having a receiving space formed therein; A magnet disposed in the accommodation space and having a plate on an upper surface thereof; A voice coil disposed between the yoke and the magnet; A diaphragm disposed at an upper portion of the plate and to which the voice coil is fixed; A cap provided at an upper opening of the yoke so that the piezoelectric element is integrally coupled to a metal plate and a rectangular piezoelectric ceramic element bonded to the upper surface of the metal plate and the piezoelectric element is disposed above the diaphragm; And a rectangular sub-metal plate bonded to the lower surface of the metal plate at a position opposite to the piezoelectric ceramic, wherein the piezoelectric ceramic has a smaller area than the metal plate, and the metal plate is provided with a piezoelectric ceramic- At least one hole is formed, and the hole includes at least one hole formed on the first corner side of the quadrangle and at least one hole formed on the second corner side of the quadrangle.

The area of the sub metal plate is preferably 50% or more and 90% or less of the area of the piezoelectric ceramics.

According to the present invention, there is provided a speaker in which a piezoelectric element composed of a metal plate and a rectangular piezoelectric ceramic bonded to an upper surface of the metal plate is disposed above a diaphragm to which the voice coil is fixed, So that it is possible to prevent the sound of the musical instrument or the voice from coming out with a rough sound or the occurrence of chiseling.

However, the effects of the present invention are not limited to those described above, and other technical effects may be derived from the following description.

1 is a side view of a speaker according to an embodiment of the present invention.
2 is a perspective view of a speaker according to an embodiment of the present invention.
3 shows a front view of a speaker according to an embodiment of the present invention.
4 is a cross-sectional perspective view of a speaker according to an embodiment of the present invention.
5 is an exploded perspective view of a speaker according to an embodiment of the present invention.
6 is a cross-sectional exploded perspective view of a speaker according to an embodiment of the present invention.
7 is a graph showing the results of measuring the frequency versus sound pressure characteristics of the speaker including the sub metal plate 33 and the speaker without the sub metal plate 33 according to the embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description and the accompanying drawings, substantially the same components are denoted by the same reference numerals, and redundant description will be omitted. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 to 6 are views of a speaker according to an embodiment of the present invention. FIG. 1 is a side view of the speaker according to the present embodiment, FIG. 2 is a perspective view of the speaker according to the present embodiment, and FIG. 3 is a front view of the speaker according to the present embodiment. FIG. 4 is an exploded perspective view of the speaker according to the present embodiment, and FIG. 6 is an exploded perspective view of the speaker according to the present embodiment.

The speaker according to the present embodiment includes a yoke 10 having a receiving space formed inside thereof, a magnet 20 having a plate 22 disposed on the upper surface of the yoke 10, And a rivet 26 for coupling and fixing the magnet 20, the plate 22 and the circuit board 50 to the yoke 10. The magnet 20, the plate 22 and the circuit board 50 are formed with holes having the same axis as that of the rivet hole of the yoke 10. Although the magnet 20, the plate 22 and the circuit board 50 are described as being fixedly coupled to the yoke 10 using the rivets 26 in the present embodiment, And may be fixed to each other.

The speaker according to the present embodiment includes a voice coil 24 disposed between the yoke 10 and the magnet 20 and a voice coil 24 disposed on the plate 22 and having an edge fixed to the yoke 10, And a diaphragm 28 fixed thereto. The magnetic field from the magnet 20 moves through the plate 22 on the magnet 20 to the yoke 10 on the lower side and constitutes a closed circuit moving again to the magnet 20. A magnetic field moving to a space between the plate 22 and the lower yoke 10 is generated in accordance with the magnetic polarity of the voice coil 24 when a current is applied to the voice coil 24 and the voice coil 24 becomes magnetized The voice coil 24 is pulled or pushed. That is, when the magnetic force polarity of the voice coil 24 is equal to the magnetic force polarity of the plate 22 and the yoke 10 on the lower side, the voice coil 24 repulsively pushes the voice coil 24 to move the voice coil 24 forward, 22 and the yoke 10 on the lower side, they are attracted to each other and pull the voice coil 24 backward. When the voice coil 24 moves in this manner, the diaphragm 28, to which the voice coil 24 is fixed, moves forward and backward to vibrate the air to generate sound. Although not shown, the speaker according to the present embodiment is provided with a wire for applying the electric signals (+, -) to the voice coil 24, and the wire is drawn out to the outside of the speaker.

The speaker according to the present embodiment is a speaker in which a piezoelectric element 30 composed of a piezoelectric ceramic 31 bonded to a metal plate 32 and a top surface of a metal plate 32 is coupled and the piezoelectric element 30 is connected to the vibration plate 28 And a cap 40 disposed at an upper opening of the yoke 10 to be coupled to the yoke 10 so as to be disposed on the upper side.

The piezoelectric element 30 is configured such that when an electrical alternating signal is applied to the piezoelectric ceramic 31 and the metal plate 32 having the piezoelectric effect, the piezoelectric ceramic 30 is extended in accordance with the elongation and contraction of the diameter of the piezoelectric ceramic 31, The sound is generated by bending up and down. The piezoelectric ceramic 31 typically has a smaller area than the metal plate 32 for bending movement of the piezoelectric element 30, so that a part of the metal plate 32 is exposed to the outside. Although not shown, the piezoelectric ceramic 31 is bonded to the metal plate 32 by an adhesive. As the adhesive, for example, a conductive epoxy adhesive, a silver paste, or the like may be used. Electric signals (+, -) applied to the voice coil 24 are also applied to the piezoelectric ceramics 31 and the metal plate 32 of the piezoelectric element 30. For example, a positive (+) signal is applied to the piezoelectric ceramic 31 and a negative (-) signal is applied to the metal plate 32. Although not shown, the speaker according to the present embodiment is provided with electrodes and wires for applying electrical signals to the piezoelectric ceramics 31 and the metal plate 32, which are also drawn out to the outside of the speaker.

Since the same electric signal is applied to the voice coil 24 and the piezoelectric element 30, a sound corresponding to the electric signal is generated in the voice coil 24 and the piezoelectric element 30, respectively. The sound generated in the diaphragm 28 due to the application of the electric signal to the voice coil 24 is a sound that is faithful to the low frequency range but is not faithful to the high frequency range. On the other hand, when an electric signal is applied to the piezoelectric element 30, (30) is relatively loud in the low frequency range but is faithful in the high frequency range. Therefore, in the speaker according to the present embodiment, a high-fidelity sound is produced in both the low-frequency range and the high-frequency range.

Furthermore, the speaker according to the present embodiment further includes a rectangular sub-metal plate 33 bonded to the lower surface of the metal plate 32 at a position facing the piezoelectric ceramic 31.

As described above, the piezoelectric element 30 generates sound by bending up and down as the diameter of the piezoelectric ceramic 31 is expanded and contracted. However, since a somewhat excessive amplitude is generated in a part of the high frequency band, It may have a negative pressure characteristic. For example, FIG. 7 is a graph of frequency versus sound pressure characteristics of a speaker including a sub metal plate 33 and a speaker without a sub metal plate 33 according to an embodiment of the present invention. Referring to FIG. 7, It can be seen that the sound pressure rises significantly in the 8 to 10 kHz band (inside the dotted circle) of the black graph in the case where the metal plate 33 is absent. This increase in sound pressure causes the sound of a musical instrument or voice to emit rough sounds or cause chippings.

In the embodiment of the present invention, the rectangular sub-metal plate 33 bonded to the lower surface of the metal plate 32 at a position facing the piezoelectric ceramic 31 suppresses excessive amplitude as described above. Since the central portion of the piezoelectric element 30 is thickened due to the sub metal plate 33 having the largest center in the amplitude of the piezoelectric element 30 and the elasticity of the central portion is smaller than in the case where the sub metal plate 33 is absent, The occurrence of excessive amplitude in the piezoelectric element 30 is suppressed. Therefore, according to the embodiment of the present invention, it is possible to prevent the sound pressure from rising significantly in a part of the high-frequency band, and to prevent the sound of the musical instrument or the voices from coming out with rough sound or chiseling.

However, if the area of the sub metal plate 33 is too large, the elasticity of the piezoelectric element 30 may be excessively decreased to thereby achieve a desired sound pressure characteristic. As a result, It is preferable that the area of the sub metal plate 33 is smaller than the area of the piezoelectric ceramics 31 and the thickness of the sub metal plate 33 is smaller than the thickness of the metal plate 32 so as not to excessively suppress the vertical bending movement.

The piezoelectric element 30 is supported by a cap 40, in which the piezoelectric element 30 is integrally coupled to the cap 40 by insert injection. In a conventional piezoelectric speaker, a piezoelectric element is fixed to a case or a supporting means using an adhesive (e.g., a silicone adhesive). In this case, there is a problem that the bonding operation is difficult and the supporting strength is not sufficient. In the embodiment of the present invention, the piezoelectric element 30 is integrally joined to the cap 40 using insert injection, thereby simplifying the manufacturing process and obtaining sufficient support strength. For example, in the embodiment of the present invention, a piezoelectric element 30 is prepared in advance, a mold for insert injection of the piezoelectric element 30 and the cap 40 is prepared, and then the piezoelectric element 30 is inserted through the insert injection molding So that the cap 40 integrally coupled thereto can be manufactured.

The metal plate 32 of the piezoelectric element 30 is generally circular so that at least a portion of the edge (e.g., a portion excluding the holes 37a and 37b) can be coupled to the cap 40. [ Unlike the metal plate 32, the piezoelectric ceramic 31 may not be circular but may have a rectangular shape as shown. In this embodiment, the piezoelectric ceramics 31 is shown as being square, but it need not necessarily be a square, but it may be a square close to a square or a rectangle.

The sub metallic plate 33 is also preferably similar in shape (although the sizes may be different) from the piezoelectric ceramics 31, and may be a square or a square close to a square or a rectangle.

In order to increase the productivity of the piezoelectric ceramics 31 in a rectangular shape, firstly, In order to manufacture piezoelectric ceramics to be used in a piezoelectric device, a large piezoelectric ceramic plate must be cut. In order to cut into a circular shape, a special cutting mechanism is required, which is not easy to work and has a problem in that the remaining portions are cut off. However, if the piezoelectric ceramic 31 is formed in a rectangular shape as in the present embodiment, a simple cutting mechanism can be used, the operation is easy, and the portion to be discarded can be minimized.

Secondly, the rectangular shape of the piezoelectric ceramic 31 is intended to improve the frequency characteristics of the sound generated in the piezoelectric element 30. [ The inventors of the present application compared the frequency characteristics of the case where the piezoelectric ceramic was formed in a circular shape like the metal plate 32 and the case where the piezoelectric ceramic was formed in a square shape as in the present embodiment. As a result, And it was confirmed that it was wide. It was confirmed that a soft sound quality was obtained when the piezoelectric ceramic 31 was made square.

The piezoelectric ceramics 31 may be a structure in which two or more piezoelectric ceramic layers are laminated. In this case, the capacity of the piezoelectric ceramic 31 is increased and the effect of increasing the negative pressure can be obtained. When the sound pressure is increased, the output becomes larger and more dynamic sound quality can be realized.

At least one hole is formed in a portion of the metal plate 32 of the piezoelectric element 30 where the piezoelectric ceramic 31 is not bonded so that sound generated from the diaphragm 28 can pass therethrough. For example, holes 37a and 37b may be formed in which a part of the edge of the metal plate 32 is inwardly folded so that the metal plate 32 is coupled with the cap 40 have. That is, the metal plate 32 can be engaged with the cap 40 along the edge which corresponds to the holes 37a and 37b and is not corresponding to the holes 37a and 37b.

Holes 36a and 36b formed on the first corner side of the square of the piezoelectric ceramics 31 and holes formed on the second corner side opposite to the first corner 36c, and 36d may be provided. By forming the holes 36a, 36b, 36c, and 36d in the metal plate 32 as described above, the raised sound pressure in the band of about 8 to 10 KHz can be lowered by about 5 to 10 dB, The sound quality can be optimized by stable change. The holes 36a, 36b, 36c, and 36d allow the sound generated from the diaphragm 28 to flow smoothly so that the sound is richer and deeper, and the balance between the high- Helping you to adjust it properly.

Further, in the embodiment of the present invention, at least one hole may be formed on the side surface of the cap 40 so that sound generated from the diaphragm 28 can pass through. Referring to Figs. 2 and 4 to 6, for example, holes 42 are formed on the side surface of the cap 40, which are located on the upper portion of the diaphragm 28.

The sound of the low-frequency range and the sound of the high-frequency range show a difference in directivity. The low-frequency sound has weak directivity while the high-frequency sound has high directivity. That is, the sound of the low frequency region tends to spread widely from the sound source, but the sound of the high frequency region tends to propagate in the same direction without spreading widely from the sound source.

Therefore, the sound in the high frequency range of the sound generated in the diaphragm 28 is partially blocked by the piezoelectric element 30 and the sound in the low frequency range tends to spread widely. Therefore, the holes 36a (36a) formed in the metal plate 32 of the piezoelectric element 30 ~ d, 37a-b. On the other hand, the sound generated by the piezoelectric element 30 is emitted as it is (or, for example, in the case of an earphone, through the earphone rubber cap).

Since there are two sound sources of the diaphragm 28 and the piezoelectric element 30 as the sound source, distortion due to the constructive interference between the sound from the diaphragm 28 and the sound from the piezoelectric element 30 may occur, This can be a problem in high frequencies. However, in the embodiment of the present invention, the piezoelectric element 30 is arranged on the upper side of the diaphragm 28, so that the sound of the high frequency band coming from the diaphragm 28 is transmitted to the piezoelectric element 30 The sound of the low frequency band from the diaphragm 28 is blocked by the holes 36a to d and 37a to b formed in the metal plate 32 of the piezoelectric element 30 and the cap 40, Such that interference can be minimized.

The sound in the low frequency range is weak in directivity and is relatively smoothly transmitted through the holes 36a to 36d formed in the metal plate 32 of the piezoelectric element 30 and the holes 42 formed in the side surface of the cap 40 And is emitted to the outside of the speaker. Particularly, by forming the holes 42 on the side surface of the cap 40, it is possible to more smoothly radiate the sound of the low frequency band which is partially blocked by the piezoelectric element 30 to the outside. However, the high-frequency sound is blocked by the piezoelectric element 30 because of strong directivity, and the holes 36a to d and 37a to b formed in the metal plate 32 of the piezoelectric element 30 and the holes formed in the side surfaces of the cap 40 And is hardly released through the holes 42. Therefore, according to the embodiment of the present invention, it is possible to provide a high-fidelity sound in both the low-frequency range and the high-frequency range while preventing the distortion due to the constructive interference between the sound coming from the diaphragm 28 and the sound coming from the piezoelectric element 30.

Referring again to FIG. 7, a graph of frequency versus sound pressure characteristics according to some cases of the area of the sub metal plate 33 is shown in a graph of the frequency versus sound pressure characteristics of the speaker without the sub metal plate 33 Are shown together.

In the absence of the sub metallic plate 33 (black graph), the sound pressure rises significantly in the 8 to 10 kHz band as described above.

A relatively high peak value is shown between 8 and 9 kHz although the rise of the negative pressure is suppressed between 9 and 10 kHz when the area of the sub metallic plate 33 is equal to the area of the piezoelectric ceramics 31 (green graph, 100%).

When the area of the sub metallic plate 33 is 50% of the area of the piezoelectric ceramics 31 (red graph), the rise of the sound pressure between 9 and 10 kHz is sufficiently suppressed and only slightly higher between 8 and 9 kHz ) Peak.

When the area of the sub metallic plate 33 is 75% of the area of the piezoelectric ceramics 31 (blue graph), the rise of the sound pressure is sufficiently suppressed between 9 and 10 kHz, and a relatively low peak value is shown even at 8 to 9 kHz.

7, when the area of the sub metallic plate 33 is 90% of the area of the piezoelectric ceramics 31, the rise of the sound pressure is also suppressed between 9 and 10 kHz and the allowable peak value between 8 and 9 kHz Respectively.

It is preferable that the area of the sub metallic plate 33 is smaller than the area of the piezoelectric ceramics 31, more preferably, it is 50% or more but less than 100% of the area of the piezoelectric ceramics 31 , More preferably not less than 50% and not more than 90% of the area of the piezoelectric ceramic 31.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (6)

A yoke having a receiving space formed therein;
A magnet disposed in the accommodation space and having a plate on an upper surface thereof;
A voice coil disposed between the yoke and the magnet;
A diaphragm disposed at an upper portion of the plate and to which the voice coil is fixed;
A cap provided at an upper opening of the yoke so that the piezoelectric element is integrally coupled to a metal plate and a rectangular piezoelectric ceramic element bonded to the upper surface of the metal plate, and the piezoelectric element is disposed above the diaphragm; And
And a sub metal plate of a rectangular shape bonded to the lower surface of the metal plate at a position opposite to the piezoelectric ceramic,
Wherein the area of the sub metal plate is smaller than the area of the piezoelectric ceramics and is 50% or more but less than 100% of the area of the piezoelectric ceramic. delete delete The method according to claim 1,
And the area of the sub metal plate is 50% or more and 90% or less of the area of the piezoelectric ceramic. A yoke having a receiving space formed therein;
A magnet disposed in the accommodation space and having a plate on an upper surface thereof;
A voice coil disposed between the yoke and the magnet;
A diaphragm disposed at an upper portion of the plate and to which the voice coil is fixed;
A cap provided at an upper opening of the yoke so that the piezoelectric element is integrally coupled to a metal plate and a rectangular piezoelectric ceramic element bonded to the upper surface of the metal plate, and the piezoelectric element is disposed above the diaphragm; And
And a sub metal plate of a rectangular shape bonded to the lower surface of the metal plate at a position opposite to the piezoelectric ceramic,
Wherein the piezoelectric ceramic has a smaller area than the metal plate, and at least one hole is formed in a portion of the metal plate where the piezoelectric ceramic is not bonded,
Wherein the hole includes at least one hole formed on the first corner side of the square of the piezoelectric ceramic and at least one hole formed on the second corner side of the square of the piezoelectric ceramic,
And the area of the sub metal plate is 50% or more and 90% or less of the area of the piezoelectric ceramic. delete

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