JP5128316B2 - Speaker diaphragm and speaker using the same - Google Patents

Description

  The present invention relates to a speaker diaphragm and a speaker using the same, which are used in various acoustic devices and information communication devices.

  Speakers are widely used not only for home or in-vehicle audio equipment but also for various electronic devices such as personal computers, mobile phones, and game machines, and there is a demand for smaller or thinner speakers. In addition, electronic equipment needs to keep component costs as low as possible, and development of inexpensive and high-quality speakers is desired.

  For micro-speakers, etc., which are required to be small and thin, to reduce costs, resin molded films such as polyethylene terephthalate ("PET") or polyethylene naphthalate ("Polyethylene naphthalate" "PEN") are used as diaphragm materials. In many cases, a fixed edge type having a diaphragm in which a diaphragm body and an edge are integrally formed of the same material is employed.

  As a material for a speaker diaphragm, in order to improve frequency characteristics as a speaker, in particular, a high elastic modulus, a large internal loss, and a low density are required. The elastic modulus affects the piston vibration band, and by increasing the elastic modulus, the width of the piston vibration band can be expanded to the high frequency side. Further, by increasing the internal loss, the sound pressure level of the resonance peak due to the divided vibration can be reduced, the vibration damping property can be increased, and the curve shape indicating the frequency characteristics can be smoothed and flattened.

  In the conventional speaker, in order to reduce the resonance peak due to the divided vibration, for example, a method of flattening the peak dip by applying a damping material having a large internal loss such as a dumping agent to the diaphragm surface has been taken. It was. However, this method requires a step of applying a dumping agent, which increases the work man-hours and the quality control man-hours.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-295245) proposes a diaphragm that increases the internal loss and realizes flattening of the peak dip in the divided vibration band by using another method. Specifically, the speaker diaphragm is formed by laminating at least first to third laminates, wherein the first and third laminates are formed of a polymer material, and the second laminate is a first laminate. It is made of a polymer material having a different mechanical internal loss from the polymer material forming the first and third laminates, thereby effectively increasing the internal loss and improving the vibration damping property, and the peak dip of the divided region It is supposed to realize the flattening.

However, it is still easy to manufacture, improving the sound pressure level in the mid-high range, flattening the peak dip in the divided vibration band, and enabling excellent sound quality reproducibility for speakers in various frequency bands There is an urgent need to develop a diaphragm.
JP 2006-295245 A

  The inventor, at the time of the present invention, pays attention to the main part laminate constituting the diaphragm for a speaker, and the laminate is made of the same material, adopting a high and low weight average molecular weight, It was found that by laminating the skin layer on the main body laminate, the peak dip in the divided vibration band can be flattened and the productivity can be improved. The present invention has been made based on such knowledge.

Therefore, the diaphragm for a speaker according to the present invention is
A polymer layer, two low molecular layers, and a skin layer,
The polymer layer is sandwiched between the two low molecular layers,
The polymer layer, the two low molecular layers are made of an acrylic-modified epoxy resin, and the weight average molecular weight of the polymer layer is larger than the weight average molecular weights of the two low molecular layers;
The skin layer is made of a saturated polyester resin, and the skin layer is provided on a surface opposite to the surface sandwiching the polymer layer in one of the two low molecular layers. .

A speaker provided by another aspect of the present invention includes:
At least with a magnetic circuit,
A voice coil disposed in the magnetic gap of the magnetic circuit and capable of vibrating back and forth;
A frame joined to the magnetic circuit;
The loudspeaker diaphragm according to the present invention is provided with an outer peripheral edge portion supported by the frame and joined to the voice coil.

  According to the present invention, it has excellent workability, has moderate elasticity, is easy to manufacture, has high internal loss, improves the sound pressure level in the mid-high range, and has a flat peak dip in the divided vibration band. It is possible to provide a speaker diaphragm that can be realized and a speaker using the same.

1. Aspect of speaker diaphragm
Usage Mode The manner in which the speaker diaphragm according to the present invention is arranged in the speaker will be described with reference to FIG. FIG. 1 is a diagram showing a half-sectional structure of a speaker according to an embodiment of the present invention. The speaker shown in FIG. 1 is a so-called internal-magnet-type speaker 1, and includes a magnetic circuit 5 having a pot-type yoke 2 that also serves as a frame, a columnar magnet 3, and a disk-shaped pole plate 4. A voice coil 6 supported in the magnetic gap is disposed below the bent portion, and a dome-shaped speaker diaphragm 7 whose outer peripheral edge is supported by the yoke 2 is provided.

Structure The structure of the speaker diaphragm 7 according to the present invention will be described. FIG. 2 is a view showing a cross-sectional structure of the speaker diaphragm 7 of FIG. As shown in FIG. 2, the speaker diaphragm 7 includes a polymer layer 21, low molecular layers 22 a and 22 b disposed in close contact with both surfaces of the polymer layer 21, and the polymer layer 21 of the low molecular layers 22 a and 22 b. The skin layers 23a and 23b are disposed in close contact with the surface opposite to the contact surface, and have a five-layer structure.

  One embodiment of the present invention has been described using such a five-layer structure. However, as a basic configuration of the present invention, the polymer layer 21, at least one of the low molecular layers 22a and 22b and the low molecular layers 22a and 22b disposed in close contact with both surfaces of the polymer layer 21 are used. It is sufficient if it is composed of a skin layer that is disposed in close contact with the surface opposite to the contact surface with 21 (four-layer structure). According to a preferred embodiment of the present invention, at least one of the low molecular layers 22a and 22b preferably covers the entire surface opposite to the contact surface with the polymer layer 21 with the skin layer. With such a configuration, the shape of the speaker diaphragm 7 can be sufficiently maintained. Hereinafter, various aspects of the speaker diaphragm of the present invention will be described.

  A configuration of a speaker diaphragm according to another aspect of the present invention will be described. 3A to 3D are partial cross-sectional views showing a configuration example of a speaker diaphragm having a layer structure different from that of the present embodiment. In FIG. 3A, the polymer layer 21, the low molecular layers 22a and 22b disposed in close contact with both surfaces thereof, and the surface of the low molecular layer 22a opposite to the contact surface with the polymer layer 21 are disposed in close contact with each other. A skin layer 23a covering the entire surface of the low molecular layer 22a, and a skin layer 23b 'partially disposed in close contact with the surface of the low molecular layer 22b opposite to the contact surface with the polymer layer 21. It has a five-layer structure. As shown in FIG. 1, the voice coil 6 may be joined to the speaker diaphragm 7. When the voice coil 6 is directly bonded to the low molecular layer 22b, the low molecular layer 22b is made of a soft material, so that it is difficult to drive the entire low molecular layer 22b even if the voice coil 6 moves back and forth. Therefore, in the present configuration example, the skin layer 23 b ′ is formed at the joint portion with the voice coil 6. For the low molecular layer 22b other than the joint portion with the voice coil 6, a skin layer 23b 'can be arbitrarily formed as necessary.

  In FIG. 3B, the polymer layer 21, the low molecular layers 22a and 22b arranged in close contact with both surfaces thereof, and the surface of the low molecular layer 22b opposite to the contact surface with the polymer layer 21 are arranged in close contact with each other. A skin layer 23b covering the entire surface of the low molecular layer 22b, and a skin layer 23a 'partially disposed in close contact with the surface of the low molecular layer 22a opposite to the contact surface with the polymer layer 21. It has a five-layer structure. Since the skin layer 23a 'is disposed on the upper surface side of the speaker and is not joined to another member, the skin layer 23a' is not necessarily required to be formed as shown in FIG. For this reason, in FIG. 3B, the skin layer 23a 'is formed only in a portion where the surface of the low molecular layer 22a needs to be protected.

  In FIG. 3C, the polymer layer 21, the low molecular layers 22a and 22b arranged in close contact with both surfaces thereof, and the surface of the low molecular layer 22b opposite to the contact surface with the polymer layer 21 are arranged in close contact with each other. And a four-layer structure. When it is not necessary to protect the front surface side of the low molecular layer 22a with a skin layer by using a center cap or a protector, this skin layer can be omitted. In this configuration example, since the skin layer is not formed on the low molecular layer 22a side, the layer configuration of the diaphragm is simplified and the productivity is improved, and the weight as the diaphragm is reduced, so that the vibration efficiency is improved. There is an advantage to increase.

  In FIG. 3D, the polymer layer 21, the low molecular layers 22a and 22b arranged in close contact with both surfaces thereof, and the surface of the low molecular layer 22a opposite to the contact surface with the polymer layer 21 are arranged in close contact with each other. The skin layer 23a covers the entire surface of the low molecular layer 22a and has a four-layer structure. In this configuration example, since the skin layer is not formed on the low molecular layer 22b side, in order to interpose the skin layer at the junction between the voice coil 6 and the low molecular layer 22b, for example, FIG. 6 and the speaker diaphragm 7a), after the skin layer 23b '' is formed at the tip of the voice coil 6, the skin layer 23b '' is lowered to the speaker diaphragm 7a. A method of bonding to the molecular layer 22b can be employed. This configuration example also has the advantage that the layer configuration of the diaphragm is simplified to improve productivity, and the weight as the diaphragm is reduced, so that the vibration efficiency is increased.

  Although the embodiments of the present invention have been described with reference to the drawings, the present invention is not construed as being limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. is there.

2. Configuration of Speaker Diaphragm 1) Polymer Layer / Two Low Molecular Layers In the present invention, a basic structure is basically a laminate in which a polymer layer is sandwiched between two low molecular layers. These three layers are preferably in close contact with each other. The polymer layer and the two low molecular layers are formed from an acrylic-modified epoxy resin.

The acrylic modified epoxy resin “acrylic (or methacrylic, hereinafter the same) modified epoxy resin” is a reaction product obtained by reacting an epoxy resin with acrylic acid (or methacrylic acid, hereinafter the same). And according to the ratio of the epoxy group and acrylic acid in the epoxy resin, an epoxy resin in which a part of the epoxy group is acrylated (or methacrylated, the same shall apply hereinafter), a partially acrylated epoxy resin, and all of the epoxy groups are completely An acrylated epoxy resin is produced. Also, a mixture of partially acrylated epoxy resin and fully acrylated epoxy resin may be formed. Partially acrylated epoxy resin, when the epoxy resin and acrylic acid are reacted, part of the epoxy group of the epoxy resin is opened and acrylated, but one or more epoxy groups are not opened It means what remains.

  Specific examples of the epoxy resin include bisphenol A type or bisphenol F type epoxy resin, novolac type epoxy resin, cresol novolac type epoxy resin, alicyclic epoxy resin, and the like. If necessary, a photopolymerization initiator and an epoxy curing agent may be added to adjust the acrylic-modified epoxy resin.

  Specifically, the acrylic-modified epoxy resin may be adjusted as follows. An epoxy resin and acrylic acid are mixed, and both are reacted in the presence of a basic catalyst according to a conventional method. The mixing ratio can be appropriately determined. For example, the mixing ratio can be 0.5 to 2 equivalents of carboxylic acid groups of acrylic acid with respect to 2 equivalents of epoxy groups of the epoxy resin. By changing the mixing ratio of acrylic acid to the epoxy group, the degree of partial acrylation (that is, the number of acrylic groups added by ring opening of the epoxy group) can be freely changed. A fully acrylated epoxy resin refers to an acrylated epoxy resin that has all of the epoxy groups ring-opened during the above reaction. For example, when a bisphenol A type epoxy resin is used, a resin in which two acrylic groups are bonded in one molecule can be mentioned.

Weight average molecular weight In the present invention, the weight average molecular weight of the polymer layer is larger than the weight average molecular weight of the two low molecular layers. At this time, the weight average molecular weights of the two low molecular layers may be the same (preferred) or different. The weight average molecular weight is specified in the relative comparison of the acrylic-modified epoxy resin constituting the polymer layer and the low molecular layer. The polymer layer has a weight average molecular weight of about 5,000 to 500,000, preferably a lower limit of 200,000 or more and an upper limit of 300,000 or less. The weight average molecular weight of the low molecular weight layer is 2,000 or more and 100,000 or less, preferably the lower limit is 2,000 or more and the upper limit is 40,000 or less. In the above numerical range, the weight average molecular weight of the polymer layer and the weight average molecular weight of the low molecular layer may overlap in number, but of course, the weight average molecular weight of the polymer layer and the weight average molecular weight of the low molecular layer It will be understood by those skilled in the art that the selection is made so that a magnitude relationship is established between and.

  The weight average molecular weight is within the above numerical range, and within this numerical range, by appropriately determining the numerical value of the weight average molecular weight of the polymer layer and the low molecular layer, desired for the speaker according to the application or installation environment It is possible to obtain a speaker diaphragm having the following mechanical characteristics (particularly frequency characteristics). More specifically, since the weight average molecular weight of the acrylic modified epoxy resin constituting the polymer layer and the low molecular layer is within the above numerical range, the speaker vibration having excellent shape stability, flexibility, flexibility, etc. The durability of the frequency characteristics of the speaker diaphragm can be improved. The speaker diaphragm according to the present invention having such characteristics can effectively prevent the low-frequency reproduction limit frequency from increasing with time, and can perform wide-band reproduction stably for a long period of time. It becomes possible. More preferably, the polymer layer and the low-molecular layer are formed from an acrylic-modified epoxy resin, and the weight-average molecular weight is within the above numerical range, so that the two low-molecular layers behave softly, The reproduction limit frequency can be lowered, and on the other hand, the shape stability as the speaker diaphragm can be maintained by maintaining the polymer layer at an appropriate strength.

According to a preferred embodiment of the layer thickness present invention, the total thickness of the three layers consisting of a polymer layer, and two low molecular layer is 15μm or more 30μm or less. Moreover, according to the preferable aspect of this invention, the thickness of each layer of a polymer layer and two low molecular weight layers is 5 micrometers or more and 10 micrometers or less, respectively. When the total thickness of the three layers and the layer thickness of each layer are within the above numerical range, the formed speaker diaphragm is excellent in shape stability and more effective in flattening frequency characteristics. It becomes. Moreover, according to a more preferable aspect of the present invention, it is preferable that the thicknesses of the two low molecular layers are the same. By using the same thickness, the stress balance of the surfaces of the respective layers can be made uniform, and physical fluctuations such as warpage can be easily prevented from occurring in the speaker diaphragm. In the present invention, it is preferable that the thickness of the three layers and the thickness of each layer be determined in accordance with the aperture diameter of the speaker (for example, about 0 mm to about 30 mm or less).

2) Skin Layer In the present invention, basically, a skin layer is provided on the surface opposite to the surface sandwiching the polymer layer in either one of the two low molecular layers. According to a preferred aspect of the present invention, the skin layer is preferably provided on the surface opposite to the surface sandwiching the polymer layer in both of the two low molecular layers.

The saturated polyester resin skin layer is preferably formed from a saturated polyester resin. In the present invention, the “saturated polyester resin” refers to, for example, a thermoplastic polyester produced by condensing a dicarboxylic acid or a lower alkyl ester thereof, an acid halide or an acid anhydride derivative and glycol or dihydric phenol. Is mentioned.

  Specific examples of aliphatic or aromatic dicarboxylic acids suitable for producing saturated polyester resins include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid. , Aromatic dicarboxylic acids such as diphenyl terdicarboxylic acid, methyl terephthalic acid and methyl isophthalic acid; aliphatics such as succinic acid, adipic acid, sebacic acid, decanedicarboxylic acid, dotecandicarboxylic acid and cyclohexanedicarboxylic acid; A dicarboxylic acid etc. can be mentioned. Of these, aromatic dicarboxylic acids, particularly terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred. Examples of the glycol component include ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentyl glycol, cyclohexane dimethanol. And polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol and the like. Of these, ethylene glycol, tetramethylene glycol, and cyclohexanedimethanol are preferred. Examples of the hydroxycarboxylic acid include α-hydroxycaproic acid, hydroxybenzoic acid, hydroxyethoxybenzoic acid, and the like.

  Specific examples of the saturated polyester resin include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and poly (1,4-cyclohexanedimethylene terephthalate). G) (PCT) or liquid crystalline polyester, or a copolymer thereof. In particular, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are preferable, and more preferable is excellent moldability. Polyethylene terephthalate (PET). In the present invention, a commercial product can be used as a film made of a saturated polyester resin. For example, in the case of a polyethylene terephthalate (PET) film, a Teijin Tetron film (manufactured by Teijin Ltd.) In the case of a polyethylene naphthalate (PEN) film, a Teonex film (manufactured by Teijin Limited) and the like can be mentioned.

According to a preferred embodiment of the layer thickness <br/> present invention, thickness of the skin layer is 1μm or more 16μm or less, preferably lower limit is 6μm or more, the upper limit is 12μm or less (more preferably 9μm or less ). When two skin layers are provided, the layer thicknesses of both may be the same or different. When the thickness of the skin layer is within the above numerical range, the speaker diaphragm can be reduced in weight and the speaker diaphragm can be easily formed. According to a more preferred aspect of the present invention, when two skin layers are laminated, it is preferable that the layer thickness of each layer is the same. By using the same thickness, the stress balance of the surfaces of the respective layers can be made uniform, and physical fluctuations such as warpage can be suppressed in the speaker diaphragm. In the present invention, the thickness of the skin layer is preferably determined so as to match the aperture diameter of the speaker (for example, about 0 mm to about 30 mm or less).

3. Manufacture of speaker diaphragm The polymer layer and the two low-molecular layers are both formed of an acrylic-modified epoxy resin, and this resin has adhesiveness. As a result, by sandwiching the polymer layer between two low molecular layers, and further laminating one or two skin layers and applying pressure, it is possible to easily obtain a diaphragm for a speaker in which the respective layers are in close contact and integrally formed. Can do. In addition, since the polymer layer and the two low molecular layers are made of the same acrylic-modified epoxy resin and the skin layer is made of a saturated polyester resin having excellent moldability, these layers are divided into four or five layers. By preparing a sheet-like laminate integrated with the structure, carrying it in a mold having a desired mold, and applying heat and pressure, a desired speaker diaphragm integrally formed can be obtained. According to this mold manufacturing method, the dome-shaped speaker diaphragm 7 shown in FIG. 2 can be easily manufactured.

4). Application of Speaker Diaphragm / Speaker The speaker diaphragm according to the present invention is mounted on the speaker as described above and in FIG. In the present invention, the speaker on which the speaker diaphragm according to the present invention is mounted can be used for an inner magnet type speaker (an example has already been shown) and an outer magnet type speaker. The shape of the speaker diaphragm according to the present invention when mounted on the speaker is not particularly limited, but may be a dome shape (speaker diaphragm 7; preferable), a conical shape, or a flat shape. The diameter of the speaker diaphragm can be determined as appropriate, but considering the layer thickness of each layer, it is more than 0 mm and about 50 mm or less, preferably the lower limit is 10 mm or more and the upper limit is about 30 mm or less. Further, the speaker 1 (FIG. 1) as an example of the embodiment of the present invention is a bobbinless speaker in which the voice coil 6 is directly joined to the speaker diaphragm 7, but the speaker diaphragm according to the present invention is It can also be mounted on a speaker having a structure in which a voice coil is wound around a bobbin and the bobbin is joined to a diaphragm.

Mode of implementation

EXAMPLE A speaker diaphragm (described below) according to the present invention was prepared, and a speaker shown in FIG.

Preparation of loudspeaker diaphragm Three-layer structure in which a polymer layer and another low-molecular layer are laminated on one low-molecular layer (each acrylic-modified epoxy resin, three-layer thickness 30 μm: the weight average molecular weight of the low-molecular layer is the same) ) And two skin layers (polyethylene terephthalate (Teijin Tetron film (manufactured by Teijin Ltd.), thickness: 6 μm)) were formed on both sides of the three-layer body to prepare a laminate. The body was carried into a mold capable of forming the shape shown in FIG. 2 and heated and pressurized to obtain a speaker diaphragm.

Comparative Example A loudspeaker diaphragm made of a single film of polyethylene naphthalate (PEN) was produced, and the loudspeaker shown in FIG.

Using the frequency characteristic measuring machine (manufactured by B & K: # 4939) for the speaker of the evaluation test example and the comparative example, the frequency characteristic is measured under the measurement conditions of a measurement distance of 0.1 m and an input of 0.1 W. As shown in FIG. FIG. 5 is a diagram showing a comparison of measurement results of output sound pressure-frequency characteristics (hereinafter also referred to as frequency characteristics) of the loudspeakers of the example and the comparative example. In FIG. 5, the solid line portion A is the frequency characteristic of the example, and the dotted line portion B is the frequency characteristic of the comparative example. As shown in FIG. 5, in the example, compared with the comparative example, the sound pressure level in the middle and high range is improved, and the peak dip in the divided region that is the high range is suppressed and flattened. Is understood.

FIG. 1 shows a half-sectional structure of a speaker according to the present invention. FIG. 2 shows a cross-sectional structure of the speaker diaphragm 7 of FIG. FIG. 3 shows various structural examples of the speaker diaphragm according to the present invention. FIG. 4 shows a method of joining the voice coil 6 and the speaker diaphragm 7a. FIG. 5 is a comparison of measurement results of output sound pressure-frequency characteristics of a conventional speaker using a diaphragm made of a single film of the speaker 1 and PEN according to the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Speaker 2 Yoke 3 Magnet 4 Pole plate 5 Magnetic circuit 6 Voice coil 7, 7a Speaker diaphragm 21 Polymer layer 22a, 22b Low molecular layer 23a, 23a ', 23b, 23b', 23b '' Skin layer

Claims (8)

A speaker diaphragm comprising a polymer layer, two low-molecular layers, and a skin layer,
The polymer layer is sandwiched between the two low molecular layers,
The polymer layer, the two low molecular layers are made of an acrylic-modified epoxy resin, and the weight average molecular weight of the polymer layer is larger than the weight average molecular weights of the two low molecular layers;
The speaker layer is made of a saturated polyester-based resin, and the skin layer is provided on a surface opposite to a surface sandwiching the polymer layer in any one of the two low-molecular layers. Diaphragm. The vibration for a speaker according to claim 1, wherein the polymer layer has a weight average molecular weight of 5,000 or more and 500,000 or less, and the low molecular layer has a weight average molecular weight of 2,000 or more and 100,000 or less. Board.   The diaphragm for a speaker according to claim 1 or 2, wherein a total thickness of three layers of the polymer layer and the two low molecular layers is 15 µm or more and 30 µm or less.   The speaker diaphragm according to any one of claims 1 to 3, wherein each of the polymer layer and the two low-molecular layers has a thickness of 5 µm or more and 10 µm or less.   The speaker according to any one of claims 1 to 4, wherein the skin layer is provided on a surface opposite to the surface sandwiching the polymer layer in both of the two low molecular layers. Diaphragm.   The speaker diaphragm according to any one of claims 1 to 5, wherein the saturated polyester resin is polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).   The diaphragm for a speaker according to any one of claims 1 to 6, wherein the skin layer has a thickness of 1 µm to 16 µm. At least with a magnetic circuit,
A voice coil disposed in the magnetic gap of the magnetic circuit and capable of vibrating back and forth;
A frame joined to the magnetic circuit;
A speaker comprising: the speaker diaphragm according to claim 1, wherein an outer peripheral edge portion is supported by the frame and joined to the voice coil.

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