WO2003007650A1

WO2003007650A1 - General-purpose loudspeaker and mounting method thereof

Info

Publication number: WO2003007650A1
Application number: PCT/JP2002/003742
Authority: WO
Inventors: Katsumi Kaitani
Original assignee: Suitaya Co., Ltd.
Priority date: 2001-07-09
Filing date: 2002-04-15
Publication date: 2003-01-23
Also published as: TW552820B

Abstract

A loudspeaker can be used in an automobile, personal computer, home theater, for BGM and the like and can faithfully reproduce an acoustic signal. When mounted in an automobile, the loudspeaker forms a soft sound field. This loudspeaker is a general-purpose loudspeaker including at least one loudspeaker unit built in a cabinet via a baffle plate. The loudspeaker unit includes an electromechanical converter for converting an acoustic output signal into oscillator oscillation, an acoustic irradiation block for irradiating the oscillator oscillation as a sound wave, and an oscillation control metal frame of approximately cone shape fixed to the converter and surrounding the acoustic irradiation block. The oscillation control metal of the frame has an oscillation attenuation ratio not less than 0.01 and Young’s modulus not less than 5.0 x 109 N/m2. Mechanical vibration generated in the converter is absorbed by the frame of the loudspeaker unit.

Description

Description General-purpose speaker and its installation method

The present invention relates to a general-purpose speaker capable of faithfully reproducing an acoustic signal for use in vehicles, personal computers, home theaters, BGM, etc., and a method of forming a soft sound field by installing such a speaker in a car, . 'Background technology

The audio spy force is a converter that generates an acoustic wave by receiving an acoustic output current from an amplifier, and generally includes a dynamic transducer and an acoustic emission unit that radiates vibration of a vibrator as an acoustic wave. The sound emitting part uses a cone or dome for small size and a horn for large size. Loudspeakers of this type are often used in combination with several different sized speakers for sound generation over a wide frequency band, and high-grade products are very expensive and require a large footprint. .

On the other hand, speakers for personal computers and vehicles are limited in their installation area by themselves, so a relatively small cone speaker unit is often used. In this type of speaker, the cone sheet of the speaker unit vibrates acoustically to generate a sound wave, and this mechanical vibration is transmitted from the baffle plate and is further transmitted to the box to easily swing the whole box. When such a box swing occurs, the low frequency of the sound generated from the corn paper is canceled, and the low range is not accurately reproduced, and the low range becomes duller or duller.

Conventionally, in order to prevent the box swing in a small speaker, a metal free wheel is conventionally installed between the frame of the speaker unit and the cone paper, and the cone makes it easy to move and absorbs mechanical vibration of the cone paper. There is. Since this free edge is not perfect even if it is a little effective and can not completely absorb the mechanical vibration of the cone paper, some vibration is transmitted to the frame of the speaker unit, and this vibration is transmitted to the box from the baffle plate to the pottass. It shakes the whole. In order to absorb mechanical vibration of cone paper, it has already been proposed to use a damping steel plate in the frame of the speaker unit. This damping steel plate is usually in the form of a sandwich with a resin layer having damping performance sandwiched between two thin steel plates, and the sandwiched resin layer is called a damping sheet. In this damping steel plate, vibration is absorbed by viscous damping that occurs when the damping sheet deforms, and this deformation depends on shear deformation of the resin layer, so even though it is theoretically thin, high damping effect can be expected. The fine vibration that is the characteristic of resin lasts longer than metal. For this reason, the emitted sound waves often overlap within a fixed time, and the sound becomes turbid, especially in the low frequency range.

The present invention has been proposed to solve the above-mentioned problems with conventional small-sized speakers, and aims to provide a general-purpose speed that can faithfully reproduce an acoustic signal and clearly reproduce a low-pitched range. And Another object of the present invention is to provide a general-purpose speaker which does not impair the sound quality by using a damping metal having a predetermined vibration damping rate and Young's modulus as either a frame or a paffle plate or mounting member. is there. Another object of the present invention is to provide a mounting method of a speaker in which an audible sound in a car becomes an indirect sound on the inner wall of the car, thereby reducing interference between sound waves and forming a soft sound field. Disclosure of the invention

The general-purpose speaker according to the present invention comprises: an electromechanical transducer for converting an acoustic output signal into vibration of a vibrator; an acoustic radiation portion for radiating the vibration of the vibrator as a sound wave; and an acoustic radiation portion fixed to the transducer The speaker cabinet consists of the surrounding, almost conical frame, and at least one speaker unit is incorporated into the cabinet via the baffle plate. Loudspeakers usually have one or two in a cabinet. If desired, the mounting member is interposed between the speaker unit and the baffle plate or between the baffle plate and the cabinet.

In the present invention, the damping metal member is a frame, a baffle plate and / or a mounting member of the speaker unit. In the frame of the speaker panel, only the flange portion of the frame may be made of damping metal. This damping metal reduces vibration Aging rate of 0.1 or more, Young's modulus of 5.0 X 10 ⁹ N / m ² or more, preferably vibration damping rate of 0.30 or more, Young's modulus of 7.0 It has physical properties of X 10 ⁹ N / m ² or more. The damping metal is, for example, a porous sintered body, an Fe-A1 based damping alloy or an A1-Si based damping alloy in which the pores of the outer surface are sparse and the pores inside are dense. In the general-purpose speaker of the present invention, the damping metal of the frame of the speaker unit, the baffle plate or the mounting member absorbs the mechanical vibration transmitted to the frame of the loudspeaker system, thereby faithfully reproducing the acoustic signal. Reproduce and clearly reproduce bass and ultra bass. The general-purpose speaker of the present invention incorporates one or two series of speaker units in a cabinet, and when the two speaker units are in series, the acoustic signal is more faithfully reproduced and the bass region is reproduced clearly. it can.

The general-purpose speaker of the present invention is preferably provided with an acoustic lens mounted on the front of the speaker. This acoustic lens consists of a hard, rough metal foam with a thickness of a few mm, and this metal foam is plastically deformed in a convex shape to control the intensity distribution and phase of the sound source, thereby appropriately controlling the directivity of the generated sound. Diffuse.

In the speaker mounting method of the present invention, a speaker unit is constituted by an electromechanical transducer, an acoustic radiating portion, and a frame fixed to the transducer and surrounding the acoustic radiating portion, and the speaker unit is cabinetd via a baffle plate. To reduce the size of the two machines built into the vehicle to automotive use. Of these two speakers, one of the speaker unit's frame, puffle plate and mounting member is made of damping metal.

In the method of the present invention, two spy forces are installed forward of the driver's seat and the front passenger's seat of the car. The two speakers should be directed forward under the driver's seat and the front passenger's seat of the car, and the front of the speakers may be arranged horizontally or upward. In this mounting method, it is possible to arrange the front of the spy force from horizontal to vertically upward, and the position of the virtual sound image shifts upward according to the orientation of the speaker. Due to the two speed powers of this structure, the audible sound in the car consists almost of the indirect sound of the car inner wall, and the low frequency range of the generated sound is sufficiently reproduced to form a soft sound field.

In addition, both speakers may be installed backwards below the dashboard, corresponding to the driver's seat and the passenger's seat. Both speakers are located under the dashboard of the car Rearward, the front of the speaker may be arranged horizontally or upward. In this mounting method, the front of the speaker can be arranged from horizontal to vertically upward. With two speakers of such a structure, the audible sound in the car mainly consists of the indirect sound of the inner wall of the car, and the low frequency range of the generated sound is sufficiently reproduced to form a soft sound field. Brief description of the drawings

FIG. 1 is a graph illustrating the regions of vibration damping rate and Young's modulus for various damping materials.

FIG. 2 is a schematic cross-sectional view showing a porous sintered body used in the present invention in an enlarged manner. FIG. 3 is a schematic side view showing a part of the speaker seat of the general-purpose speaker according to the present invention.

FIG. 4 is a schematic cross-sectional view showing another general purpose spy force according to the present invention.

FIG. 5 is a cross-sectional view of an essential part showing another example of the general-purpose speaker.

FIG. 6 is a cross-sectional view of an essential part showing an example of a general-purpose speaker having another mounting member. FIG. 7 is an explanatory view showing a method of measuring a speaker characteristic in a flowchart. FIG. 8 is a graph showing the eyelid area in the speaker characteristic for the speaker of the present invention.

FIG. 9 is a graph showing the time domain in the speaker characteristics for a speaker attached with a wooden paffle plate.

FIG. 10 is a schematic explanatory view of a plating reaction apparatus used for producing a metal foam. Figure 11 shows the frequency characteristics of a commercially available speaker with and without a porous sintered body mounting member between the conical frame and the enclosure of the speaker unit. It is a graph.

FIG. 12 is a schematic cross-sectional view showing an example of a general-purpose speaker incorporating two speaker units.

Figure 13 is a graph that displays the time domain in the speech characteristics and (b) the frequency domain for single and double speakers.

Figure 14 shows that one baffle plate is the name of two double speakers with the same structure. It is a graph which shows the frequency characteristic of the case where it is a porous sintered compact, and the case where the other puffle board is wood.

Figure 15 is a graph that shows the frequency response for a speaker unit with an aperture of 10 cm.

Figure 16 is a graph showing the frequency response for another speaker of aperture 10 0 c m.

FIG. 17 is a graph showing the frequency characteristics with respect to double-speaking power using the two speaker units of FIG. 15 and FIG.

FIG. 18 is a schematic cross-sectional view showing another example of a general purpose speaker incorporating two speaker seats.

FIG. 19 is an acoustic diagram drawn at the installation position of the on-vehicle speaker according to the present invention, (a) is a side sectional view of a passenger car, and (b) is a horizontal sectional view.

FIG. 20 is an acoustic diagram drawn at another installation position of the vehicle speaker of the present invention, (a) is a side sectional view of a passenger car, and (b) is a horizontal sectional view.

Fig. 21 is an acoustic diagram drawn at the installation position of a conventional in-vehicle speaker, where (a) is a side sectional view of a passenger car and (b) is a horizontal sectional view.

FIG. 22 is a graph showing the time domain in the speaker characteristics and (b) the frequency domain at the installation position of the on-vehicle speaker in FIG.

Fig.23 is a graph showing the same speaker characteristics as Fig.22 for a car different from Fig.22.

FIG. 24 is a graph showing the same speaker characteristics as in FIG. 22 at the installation position of the existing on-vehicle speaker for the same automobile as in FIG. BEST MODE FOR CARRYING OUT THE INVENTION

In the general-purpose speaker 1 according to the present invention, any or a plurality of portions of the frame, the baffle plate and the mount member of the speaker unit are made of damping metal, and only to the flange portion (see FIG. 3 reference numeral 33) of the frame. It is also possible to use damping metal. The speaker 1 is a product for a vehicle, a personal computer, a home theater, a BGM, a general audio device, etc., and the speaker may be a woofer. Speaker 1 In general, it is preferable that the structure be relatively simple and inexpensive, and be small enough to be installed in a limited narrow space. In the present invention, the acoustic radiation part of the speaker unit may be any of a cone, a dome or a large horn.

In the present invention, the damping metal includes single metals, alloys and composite metals, but does not include composite products such as known damping steel plates in which a metal plate and another material are laminated. This damping metal needs to have physical properties such as a vibration damping factor of 0.01 or more and a Young's modulus of 5.0 X 10 ⁹ N / m ² or more. The factor is the logarithmic damping factor in the damping free vibration of the material, and the Young's modulus is the ratio of the tensile or compressive stress in the solid to the strain in that direction. Vibration attenuation rate Power is less than SO. 0 1. Distortion is likely to occur in the sound of low frequency range, and when Young's modulus is less than 5.0 X 10 ⁹ NZm ² , micro-vibration continues for a long time and turbidity occurs in the sound. Preferably, the vibration attenuation factor is not less than 0.33 and the Young's modulus is not less than 7.0 × 10 ⁹ N / m ² , and the acoustic signal is reproduced so faithfully in this range, the bass range and the ultra low range It can be expected to clearly reproduce the range.

FIG. 1 is a graph showing regions of vibration damping rate and Young's modulus for various damping materials. In Fig. 1, as a damping metal having a vibration damping ratio of 0.1 or more and a Young's modulus of 5.00 x 10 ⁹ N / m ² or more, a porous sintered body having different pore sizes in the inner and outer regions 2 F 1-A 1-based damping alloy 3 (trade name: M205 2, manufactured by the Institute of Thermal Science), Al-Si based damping alloy 4 (manufactured by limited company Suisaku Co., Ltd.) manufactured by powder metallurgy The vibration damping metal which is not used can also be used if it has a predetermined vibration damping factor or Young's modulus.

The above-mentioned damping metal has a vibration damping rate of not less than 0.10, and therefore has the same sound absorbing action as a conventional sound absorbing material such as glass wool and felt, and also has a Young's modulus of 5.0 X 1 0. ^As it is ⁹ NZm ² or more, it is rigid and does not absorb vibration by displacement like rubber and panels. This vibration damping metal prevents mechanical vibration of the frame of the speech force machine as the cone paper vibrates when the cone paper in the speaker unit vibrates acoustically. As there is no displacement, mechanical vibration is not transmitted to the speaker unit.

The porous sintered body 2 having desired physical properties is a metal product invented by the present inventor, It is a rigid product with a rough surface, and is produced by heating directly and electrically heating metal flakes such as iron and steel and applying pressure (Japanese Patent Publication 5 8 5 2 5 2 8, U.S. Pat. No. 4 4 4 3) 4 0 4 (see Japanese Patent No. 3 2 5 0 0 6)). The porous sintered body 2 is a sound absorbing material capable of absorbing a sound wave having a large energy frequency, and is a hard material different from conventional glass wool, felt and the like. As shown in FIG. 2, when a sound wave strikes the porous sintered body 2 as shown by the arrow a, it is sucked into the depressions of the outer surface 5 of the rough pores, and then, as shown by the arrows b and b, It is compressed in the interior 6 and escapes to the outside as very minute heat.

The porous sintered body 2 is generally formed into a flat plate shape by current heating and pressurization using a metal chip having a particle diameter of 6 to 50 mesh. During this molding, the surface of each metal tip melts and fuses between the tips, and the heat escapes to the inside of the sintered body for cooling, so the pores of the outer surface 5 become sparse and the pores of the inner 6 become dense. (See Figure 2).

The porous sintered body 2 is obtained from one or more metal chips. The metal chip is metal powder or chips (dalai powder) or the like, and an alloy having two metal components may be mixed, or a plurality of metal chips having different shapes and types may be mixed. As this metal tip, pig iron cuttings, carbon billet, iron-based metal such as stainless steel billet, aluminum-based powder, aluminum alloy such as Al-Si alloy cuttings, copper-based metal, titanium For example, titanium-based metals such as powders can be exemplified.

In addition to the metal chips, a small amount of glass particles, ferrite powder, cement powder and / or thermosetting resin may be added to the porous sintered body 2 for integration. The thermosetting resin is epoxy resin, polyester resin, phenolic resin, diaryl resin, etc. It is also possible to add it in combination with other additives. Even if the porous sintered body 2 contains a small amount of ceramic, synthetic resin or the like, it is possible to exhibit desired anti-vibration properties by integrating these.

In the porous sintered body 2, when the amount of the additive is about 10% by weight or less of the total amount, the porous property is sufficiently maintained, and when it is 10 to 25% by weight, the vibration damping property is slightly reduced. In the porous sintered body 2, if the content of the metal tip is about 75% by weight or more of the total amount, it can be used as a damping metal, and about 90 weight for high performance spying applications requiring high vibration damping rate. It is preferable that it is% or more. The porous sintered body 2 is manufactured, for example, by a molding apparatus (not shown) having a square cylindrical mold, and the mixed metal chips are filled in the mold. In this forming apparatus, a pair of rectangular electrode plates having the same surface area are installed facing each other on a horizontal ceramic plate, and a pair of rectangular heat-resistant side walls are installed orthogonal to this. It constitutes a formwork. Connect the wire from the low voltage transformer to the side end of one electrode plate, and also connect the wire to the opposite side end of the other electrode plate.

Raw metal chips are placed almost uniformly in a mold, and then the press die is lowered to form a flat plate by applying a high current of several thousand amperes and applying heat and pressure. At the time of sintering, a high current of up to 800 amperes is applied to the metal tip for thermoforming, and the voltage is usually 20 volts. At this time, even if the heating temperature reaches around 1000 ° C. in the mold, volume diffusion is hardly caused by flowing a high current. In addition, phenomena such as spheroidization of the air gap and reduction or disappearance of the micro air gap do not occur, and they are partially melted and bonded to each other at the contact portion between the metal chips.

Even if the sintered plate obtained is finished on a rectangular plate provided with a central hole and used as it is for a puffle plate, if it is small like a mounting member, it is cut appropriately and then finished on one or both sides. Polishing may be used, and a plurality of sheets may be combined in an annular shape and used. In addition, a thin cover layer of several mm in thickness may be provided on the surface of the sintered plate as a baffle plate or mounting member, and this thin cover layer is made of, for example, synthetic resin, metal or general purpose ceramic. This sintered plate can also be applied to the frame of a Spy force union by reheating into a three-dimensional shape by heating or reheating before cooling.

'For the general-purpose speaker 1 and the woofer, depending on the application site of the damping metal, select the porous sintered body 2, Fe-Al I-based damping alloy 3, A1-Si-based damping alloy 4 etc. as appropriate do it. For example, it is preferable to apply damping alloys 3 and 4 which can be relatively easily formed in three dimensions to the frame 8 of the speaker unit 7 shown in FIG. 3, and if it is only the flange portion of the frame Either of 2 or damping alloys 3 and 4 can be used. For the baffle plate 10 shown in FIG. 4 and the mounting members 12 and 14 shown in FIG. 5 and FIG. Flat plate damping metal is glued or fixed as baffle plate 10 or mounting member 1 2, 14 do it. Mounting members 1 and 2 2 are usually an annular body having a rectangular cross section or L-shaped cross section as shown in FIG. 5, and even if only a part of the annular body is a damping metal, The metals may be distributed in the circumferential direction only.

If desired, a convex plastically deformed metal foam body 16 (FIG. 4) may be mounted on the general-purpose speaker 1 so as to cover the front face of the cabinet 17 or the baffle plate 10. The metal foam body 16 can be interpreted as a metal plate in which irregular large continuous pores having a thickness of several millimeters are formed throughout. The metal foam body 16 is usually made of nickel with little shielding of electromagnetic waves, and where the shielding of the electromagnetic waves is needed, a metal corresponding to that is used. The metal foam body 16 has an apparent density of 1.0 or less, and a large number of elongated metal filaments randomly extend in the width direction and combine to form a generally relatively stiff network shape as a whole. It can be manufactured by a plating reactor 25 as exemplified in FIG.

As shown in FIG. 7, the measurement of the peaker characteristics applied in the present invention is performed not by the conventional steady state sweep method but by the pulse input method. The steady state sweep method uses only the level fluctuation of each frequency as the speaker characteristic, while the pulse input method is measurement in the time domain. As shown in Fig.13 and Fig.22 to Fig.24, using the FFT method, if the speaker characteristic is not only the pulse response in the time domain (a), but the reference level is the same, the phase is selected. It is possible to compare the transfer functions in the frequency domain (b) containing the information. For the input signal, a square wave pulse with a time width of 50 microseconds is used. This signal has flat characteristics up to about 10 kHz in the frequency domain, and then drops sharply at 2 0 kHz.

In FIG. 7, the rectangular wave pulse of the input signal recorded on the CD-ROM is amplified by the audio amplifier 18 and supplied to the speaker 19. Sound waves from the speakers are recorded from the microphone 2 0 through the amplifier 2 1 to the DAT (digital audio tape recorder) 2 2. After measurement, reproduce DAT, analyze it using FFT analyzer 2 3, and organize data on personal computer 2 4. The measurement room is located in the factory of Suitaya Co., Ltd. At least 100 times of averaging (averaging) should be performed to improve the SN ratio as a measure against noise, and measurement results are obtained. Sounds reflected from floors, walls and ceilings are processed only for direct sound from spy force Even if you remove it, you can get a direct sound with a sufficient length of time, and all the following experiments are also done by this method. Next, the present invention will be described based on examples, but the present invention is not limited to the examples. The speaker unit 7 shown in FIG. 3 may be disposed in a box-shaped cabinet in the small speaker 1 illustrated in FIG.

The speaker unit 7 generally has a conical perforated frame 8 which covers the whole of the cone paper 30 and fixes the magnet portion 32 on the flat top of the frame. A cylindrical excitation coil (not shown) is attached to the inside of the magnet section 32, and the cone paper acoustically vibrates with the excitation coil by pasting the center top portion of the cone paper 30 on one side of the coil. By pasting the annular peripheral portion of the corn paper 30 onto the annular inner circumferential surface of the frame 8, the corn paper is stretched to produce sound stably. The frame 8 made of damping metal is made of damping alloy 4 (see FIG. 1) which is relatively easy to form in three dimensions, and the damping alloy is formed into a thin-walled hollow cone.

The conical frame 8 has a flange 33 at its front end. The flange portion 33 is fixed to a baffle plate (not shown) provided with a circular hole, and this fixing is bolting or bonding. Generally, it is preferable to bolt the flange portion 33 at three points at equal intervals in the circumferential direction with respect to the baffle plate. The planar shape of the outer periphery of the baffle plate is a rectangle substantially the same as the inner dimension of the cabinet, and the baffle plate is vertically clasped or adhered to the inner circumferential wall of the cabinet.

In the speaker unit, only the flange portion 33 of the frame 8 may be made of the damping metal 4, and the other conical portion of the frame may be made of ordinary metal. In the frame 8, the flange portion 33 and the other conical portion may be integrated by welding or an adhesive.

The compact force unit 34 shown in FIG. 4 is placed in the box shaped cabinet 17 with the compact compact force 1. The speaker unit 34 has a conical frame 36 covering the whole of the cone paper 35, and the magnet portion 38 is fixed to the flat top of the frame. The cone paper 35 vibrates acoustically with the exciting coil in the magnet unit 38. For the puffle plate 10, use a porous sintered body 2 (see FIG. 2) which is a damping metal. The conical frame 36 is inserted into the central hole 40 of the baffle plate 10, and the flange portion 42 on the front peripheral end is fixed to the puffle plate 10, and this fixing is port fixing or bonding. In the baffle plate 10, an annular groove 44 is formed on the front inner periphery of the central hole 40 to be engaged with the flange portion 42. The planar shape of the baffle plate 10 is substantially the same rectangle as the inner size of the cabinet 17. The baffle plate 10 is clasped or bonded vertically to the inner circumferential wall of the cabinet. Preferably, the flange portion 42 of the frame 36 is bolted to the puffle plate 10 at three points at equal intervals in the circumferential direction.

The box-like cabinet 17 constitutes a speaker box together with the baffle plate 10, a through hole 46 for heat radiation is provided on the side wall, and the connector receptacle 4 7 is attached to the cabinet rear wall. It is preferable to set the stand 48 so that the cabinet 17 is placed upward.

In order to produce the porous sintered body 2 shown in FIG. 2, although not shown, a pair of rectangular electrode plates having the same surface area are installed opposite to each other on a horizontal heat-resistant ceramic plate. Then, use a molding apparatus that forms a mold by installing a pair of rectangular heat-resistant side walls. The dimensions of this form are: base area 6 75 x 6 5 mm and height 15 cm. Thermocouples are inserted into the horizontal ceramic plate, and it is possible to measure the temperature in the mold. A release sheet is laid flat on the bottom of this formwork, and a pig iron (FC-25, content: about 3.5% carbon, about 2.5% carbon, about 0.5% manganese). 1) Insert 7 kg of chips (dalai powder), evenly distribute to a thickness of about 30 mm, and lay the release sheet flat.

In the above-mentioned forming apparatus, the ceramic press die is lowered and at the same time the power is turned on, and the press die is lowered and pressurized until the current reaches 500 amperes. When the pressure is continued at a pressure of 120 kg / cm ² , the current passing through the mold rises rapidly from 0 to 5000 amps, and then gradually continues to increase, and after pressure 1 0 to 1 2 Reaches 6400 amperes in minutes. Since the current is equilibrated at 6400 amperes, raise the press mold here and take out the sintered plate and cool it.

The sintered plate is appropriately cut and processed, and further finish polished to obtain a baffle plate 10. The obtained porous sintered body 2 has a porosity of about 50%, and the pores on the outer surface are somewhat sparse in the thickness direction and the pores in the inner part are dense. The porous sintered body 2 has a vibration damping rate of ( 77) = 0.14 It is a damping metal with a Young's modulus of 1.2 X 1 0 ^ N / m ² .

In the case of the small speaker 1, the mechanical vibration which is the reaction of the acoustic vibration of the cone paper is placed on the frame 36 in order to install the speaker unit 34 in the cabinet 17 via the porous sintered body 2 of the porous sintered body 2. Even if it is transmitted, the mechanical vibration can be absorbed by the porous sintered body 2 of the baffle plate 10. When the cone paper 35 vibrates according to the sound signal from the amplifier, the puffle plate 10 does not transmit the mechanical vibration transmitted from the cone paper to the cabinet 17.

In FIG. 8, as an experimental example, a puffle plate of porous sintered body 2 of pig-iron is attached to a 3 cm speaker with an aperture, and the time domain in the speaker characteristic is displayed. As a comparative example, in Fig. 9, a wooden baffle plate is attached to the 3 cm speaker. In Figure 8, the positive peak value following the first negative peak is about 20 d B greater than that in Figure 9. The porous sintered body 2 made of pig iron used in FIG. 8 has a high vibration damping property and is a rigid material so that the spy force union 34 can be fixed firmly. The porous sintered body 2 of pig iron has a higher mechanical vibration of the unit 34, which is the reaction, when the film surface of the cone paper moves, as compared with the wood shown in FIG. When the film surface becomes so smooth, the amplitude range widens, and the input signal becomes more faithfully reproduced. The wood in Fig. 9 is easy to move according to its natural frequency, which adversely affects the movement of the film surface of corn paper.

In the small speaker 1 shown in FIG. 4, a convex plastically deformed metal foam body 16 is attached so as to cover the front face of the cabinet 17 or the baffle plate 10. The metal foam body 16 has an apparent density of 1.0 or less, and a large number of elongated nickel pieces extend in the width direction and randomly bond to form a three-dimensional network shape as a whole, and its thickness is about It extends to 2 mm.

The metal foam body 16 is manufactured using a 'rolling reactor 25 as schematically shown in FIG. In reactor 25, the open-aired styrene plates 27 and 27 are attached to the metal plate 26 of the force sword, and the metal plate is a material having high removability from nickel, and the releasability is high. Apply surface treatment as you like. On the other hand, the anode is a nickel plate 28 and the nickel plating bath contains nickel sulfate, nickel chloride, boric acid, a complexing agent and the like. In Reactor 25, when a constant potential is applied using external power supply 29, in the cathode, nickel ions diffuse from the inside of the solution through the air bubbles in polystyrene plate 27 and approach the electrode interface, It receives electrons and is reduced to metallic nickel. At this time, since metallic nickel is present only in the bubble portion of the polystyrene plate 27, it grows randomly and bonds along the bubble portion. When the deposition of metallic nickel reaches a few millimeters, take out the force Sword, peel off the polystyrene plates 27 and 27 from the metal plate 26 and remove the styrene portion. After appropriate surface finishing, a flat metal foam 16 is obtained. The metal foam body 16 can be plastically deformed in a convex shape by a press die or a hand.

The metal foam body 16 can appropriately diffuse the directivity of the generated sound by controlling the intensity distribution and the phase of the sound source as an acoustic lens. The sound wave emitted from the speaker unit 34 generates a new sound wave surface on the net surface by the irregular holes of the metal foam body 16. From this sound wave surface, a sound wave passing straight through the pores of the metal foam body 16, a sound wave which strikes the net once and a sound wave which bounces once, and a sound wave which is diffracted in various directions hit the boundary surface of the pores. Further, since the metal foam body 16 is a light but hard material, the sound wave is not absorbed by the metal foam body 16 and can pass without changing the sound quality. In other words, the sound waves emitted from the speakers reach the net surface, where they travel straight and are diffracted and diffused to spread out from the net surface to the space outside. Even if sound waves emitted from spying force have some directivity and frequency level difference, the sound quality does not change when it passes metal foam body 16, and it becomes a stable sound wave that diffuses widely. .

The speaker with the metal foam 16 attached was examined for frequency characteristics in which the direction of the sound receiving point is the front of the speaker (0 degrees), the inclination is 30 degrees, and the angle is 60 degrees. Compare with the frequency characteristics of 0 degree, 30 degrees, and 60 degrees when body 16 is excluded. The frequency characteristics also depend on the size and number of pores in metal foam body 16, but the difference appears well in the low range. In the case of the speaker having the metal foam body 16, the output sound pressure level gradually decreases from 0 degrees to 60 degrees, whereas in the speaker without the foam body, the bass range at 30 degrees The sound pressure level is raised, generating an unstable sound wave. FIG. 5 shows another modification of the present invention, in which the conical frame 3 6 of the speaker unit 3 4 is inserted into the central hole 5 1 of the baffle plate 50, and the mount of the porous sintered body 2 The members 1 2 are interposed between the rear surface of the flange portion 4 2 of the speaker unit 3 4 and the front surface of the baffle plate 5 0 and fixed by means of three or four points in the circumferential direction. . Puffle board 50 is made of normal wood or metal. The mount member 12 is an annular body having a rectangular cross section and an inner diameter substantially equal to the central hole 5 1 of the puffle plate 50, and is made of a combination of a single or a plurality of small pieces of porous sintered body. The mounting member 12 also serves to position the speaker unit 34 forward. Also, the mount member 14 shown in FIG. 6 is interposed between the puffle plate 52 and the cabinet 17, and the puffle plate is made of ordinary wood or metal. The conical frame 3 6 is inserted into the center hole 5 3 of the puffle plate 5 2, and the flange portion 4 2 at the front end and the front circumferential surface are fixed to the center hole 5 3 of the puffle plate 5 2. The mounting member 14 is a combination of elongated plate members having a rectangular cross section, which has substantially the same thickness as the baffle plate 52, and the upper and lower surfaces between the outer peripheral surface of the baffle plate 52 and the inner wall of the cabinet 17 Glue or clamp or bolt individually. Place the front of the baffle plate 54 for the decoration mainly.

The mounting members 12, 14 absorb mechanical vibration transmitted from the cone paper 35 to the frame 36 of the speaker cushion 34. The mounting members 12, 14 do not transmit the mechanical vibration transmitted from the cone paper to the cabinet 17 when the cone paper vibrates according to the sound signal from the pump, so that the mechanical vibration is combined with the sound wave and the acoustic wave. It will not be done. Therefore, with this speaker, the sound pressure level in the low frequency range rises, and the sound pressure level in the audio frequency range approaches flat, and the speaker characteristics improve. In the mounting member 14, since the mechanical vibration of the baffle plate itself can not be avoided, the vibration noise generated from the baffle plate may have some adverse effects.

As an example, in FIG. 11, a porous sintered body 2 between a conical frame of a speaker screen and an enclosure in a commercially available 38 cm diameter aperture (manufactured by UREI, model 8 11 B). Compare the frequency characteristics of the case where the mounting member 1 2 is intervened and the case where it is not intervened (in the original state). When the frequency characteristic is measured, when the mount member 1 2 is interposed, it is in the low frequency range of frequency 40 0 to 5 OH z or less Sound pressure level is rising. This sound pressure level rise is due to the vibration damping property being high, and the hard porous sintered body 2 absorbs mechanical vibration of the spy force unit itself, and it does not transmit box noise etc. to the enclosure, ie the speaker box, and a low frequency band signal. The result is that the film surface of the corn paper moves precisely to the sound. As a result, in this speaker, the sound pressure level in the audio frequency band approaches flat, and the speech power characteristics are generally improved. On the other hand, in the original state, the reaction of the acoustic vibration of the cone paper is transmitted to the frame of the speaker unit, and further transmitted to the cabinet, and the whole bottus is oscillated by mechanical vibration. Such low-frequency sound in the low frequency range is lowered by canceling out the low frequency of the sound generated from the cone paper by such box oscillation, and the low frequency range is not accurately reproduced.

Although not shown, in the case of a speaker with an aperture of 3 O c m (manufactured by J B L), an increase in sound pressure level can be found at a frequency of about 70 Hz or less. As described above, the rigid porous sintered body may be attached to a commercially available speaker as a retrofit mounting member, or may be previously incorporated as a part for fixing the spy force union to the enclosure. Also, in the case of a 10 cm diameter speaker, the sound pressure level rises in a low frequency range of about 200 Hz or less when comparing the porous sintered body mounting member with the wooden mounting member. .

FIG. 12 shows a speaker 57 in which two speaker units 5 5 and 5 6 are built in front and back. The speaker units 55 and 56 usually have conical frames 58 and 59 which have the same shape and function and cover the whole of the corn paper (not shown). Secure the magnet parts 60 and 61 on the flat top of the. A cylindrical voice coil (not shown) is attached in the vicinity of the magnet parts 60 and 61, and the cone paper vibrates together with the coil by pasting the center top of the cone paper on one side of the coil. .

The frame 58 of the front sheet 55 is inserted into the center hole 63 of the puffle plate 62, and the flange portion 64 of the front peripheral end is adhered or fixed to the baffle plate 62 by adhesion. An annular groove 65 is formed in the front inner periphery of the central hole 63 in the nozzle plate 62 to be engaged with the flange portion 64. The planar shape of the baffle plate 62 is substantially the same as the inner size of the cabinet 66 and is rectangular. Meanwhile, the frame 5 9 of the rear unit 5 6 is The flange 70 is fitted in an annular groove 69 formed in the rear inner periphery of the central hole 68 of the plate 67 and fixed by means of a port stopper or adhesion. The baffle plates 62 and 67 have a porous sintered body of a predetermined shape coated with a thin resin.

Two wooden boards 71, 71 having substantially the same shape and thickness as the puffle board are disposed between the knock boards 62, 67. Glue all four plates in intimate contact and clasp or glue vertically to the inner circumferential wall of cabinet 66. The slightly elongated box-shaped cabinet 66 constitutes a speaker box together with the puffle plates 62 and 67. A through hole 72 for heat dissipation is provided on the side wall of the cabinet 66, and the connector receptacle 7 3 is attached to the cabinet rear wall.

In the speaker 57, even if the reaction of the acoustic vibration of the cone paper is transmitted to the frame 58, 59 of the speaker unit 55, 56, the mechanical vibration is generated by the porous sintered body of the puffle plate 62, 67. By absorbing the sound signals and inputting the same sound signal to the speaker units 55 and 56, both speaker units will be acoustically vibrated in the same phase at the same time. With this operating environment, the film surface of the front cone paper is more easily acoustically vibrated in response to the vibration of the film surface of the rear cone paper. Smaller-bore speakers make it difficult to accurately reproduce the low-pitched range, while the double-tuned Spy force 57 can confirm an increase in sound pressure level in the low-pitched range.

In FIGS. 13 to 17, the speaker seats used in the experiments all have the same aperture of 10 cm, and each speaker is an embodiment excluding the metal foam body 74. In Fig.13, the speaker characteristics of the single speaker and the double speaker are compared. The single speaker unit is single speaker unit, and the double speaker unit is a series of two speaker units as described above. All have the same structure. In Fig.13, the single-speaker sound pressure level in the low-frequency range rises, and the double-speaker sound pressure level in the low-frequency range further improves than the single-speech force.

Figure 14 shows the respective frequencies for two double pull- ing forces of the same structure, one using the porous sintered body (brand name: Rusk) for the baffle plate on the one hand and the baffle plate being wooden on the other hand. The characteristics are compared. In Fig. 14, it can be seen that the double speaker using the baffle plate of porous sintered body has a much higher sound pressure level than the wooden baffle plate in the reproduction of the low frequency range. Figures 15 and 16 show the frequency response of two different loudspeaker units with an aperture of 10 cm, and both loudspeaker units have large dips in the high range. On the other hand, Fig. 17 shows the frequency characteristics of a double speaker in which two of these two speaker units are mounted in series. Although both speakers had dips in the high range, the sound pressure level in the low range increased further when the double speakers in Figure 17 were used, and the sound pressure in the high range showed more stable characteristics. There is. From Fig.13 to Fig.17, the double speed using the porous sintered body baffle plate raises the sound pressure level in the low frequency range compared to a normal speaker, and the different speed units are different. In the case of using, it turns out that it has the characteristic to catch the fault of each set.

The speaker force 75 shown in FIG. 18 incorporates the front speaker unit 76 vertically and the rear speaker unit 7 horizontally. The speaker units 7 6 and 7 7 usually have the same shape and function. The frame 7 8 of the front unit 7 6 is fixed to the resin-coated porous sintered body baffle plate 7 9. The rear of the front window 76 is enclosed by a cabinet 80, and in this enclosed space 81 a cone of paper (not shown) in the frame of the rear window 77 opens. The frame 82 of the rear seat 76 is fixed to a baffle plate 83 of a porous sintered body coated with resin, and the baffle plate 83 is disposed horizontally below the speaker unit 77. Fix or bond the inner circumferential wall of the cabinet 80.

Spy force 75 is the same as Spy force 57 shown in Fig. 12. Even if the reaction of the acoustic vibration of the cone paper is transmitted to frames 78 and 82, the mechanical vibration is applied to puffle plates 79 and 83. The absorption by the porous sintered body and the vibration of both speaker units 7 6 and 7 7 are synchronized back and forth, so that the mechanical vibration is effectively attenuated. Since the speaker 75 is vertically long and similar in shape to a conventional speaker, it is not limited in application.

Fig. 19 to Fig. 21 are sound diagrams drawn according to the installation position of the vehicle speaker, and the speaker 1 as illustrated in Fig. 4 is appropriately deformed and miniaturized to form a vehicle speaker. It is preferable to use. The speaker that can be installed is effective with normal speed instead of speaker 1, and two sets of speed units as shown in Fig. 12 are combined. It may be a speeing force.

In Figure 19, the speakers 8 4 and 8 4 are installed forward of the lower center of the seat or slightly in front of the lower part of the driver seat 8 7 and the front passenger seat 8 8 of the automobile 8 6. When the front of the speakers 8 4 and 8 4 are arranged horizontally below the driver's seat 8 7 and the passenger's seat 8 8, the direct sound from both of the two spins is mostly reflected at the front of the car and audible sounds from people inside the car Mainly becomes indirect sound. When this indirect sound converges, the virtual sound images 90, 90 will be located in front of the car. In Fig. 20, speakers 91 and 91 correspond to driver's seat 8 and passenger's seat 8 of automobile 8 and are installed backwards under the dashboard. When the fronts of the speakers 9 1 and 9 1 are arranged horizontally, part of the direct sound from both speakers radiates in the direction of the driver's seat 8 7 and the passenger's seat 8 8 but most of the sound comes from the seats It will not be heard directly as it will reach the lower half. Most of the direct sound travels upward on the surface of the dashboard, is then reflected by the windshield on the front of the car, and is reflected by the inner side of the car, so these indirect sounds are audible to the person in the car. It becomes. In terms of volume and clarity, the positions of the speakers 9 1 and 9 1 are larger than the positions of the speakers 8 4 and 8 4.

On the other hand, FIG. 21 shows sound diagrams emitted from each speaker in a conventional automobile (for example, product name: Corolla) in which two speakers 92 and 92 are installed on the left and right of the dashboard. In Fig.21, in the front driver's seat 8 7 and the front passenger's seat 8 8 a loud direct sound is received from the near sound power 92 and then a direct sound from the distant speaker is received. After that, you will hear the sound that has been repeatedly and repeatedly reflected by doors, windows, ceilings, back windows, and so on.

As shown in Figure 19, when spies 8 4 and 8 4 are installed under the seat, the direct sound emitted from the near spin goes around the seat and reaches the listener on the front seat first. Continue to receive the direct sound of the distant speaker. That is, instead of receiving a large direct sound from nearby, you will first hear the diffracted sound that travels around the seat, and then you will hear the sound reflected by the door or ceiling. On the other hand, a direct sound that travels forward in the space of the foot of the front seat without being diffracted becomes a reflected sound with a time delay, reaches the listener, and this reflected sound is reflected in multiples in the car. Become. Figure 2 In the case of 0, you will first hear some direct sound going straight ahead, but the position of the speaker that emits this direct sound is quite far from it, and it is similar to cause time difference in the sound that listener 1 listens to. is there.

FIG. 22 is a graph showing the speaker characteristics of the known automobile (trade name: Corolla) measured by the speaker force 84 and 84 disposed under the seat shown in FIG. FIG. 23 is a graph in which the speaker characteristics by the speakers 8 4 and 8 4 installed under the seat of FIG. 19 are measured at the front passenger's seat for another known automobile (trade name: Celsior). Figure 24 is a graph of the same characteristics of the vehicle shown in Figure 23 (trade name: Celsior), with the speaker characteristics measured at the passenger's seat measured by a number of loudspeakers installed at conventional positions. Each sound source is a square wave pulse as shown in FIG.

In the speakers 8 4 and 8 4 installed under the seat, in the time domain of Fig. 2 2 (a), a not so loud sound arrives first, followed by a certain amount of loud sound, and Fig. 2 4 ( It is a sound field diffused as in a). In the frequency domain in Fig. 2 2 (b), it has almost flat characteristics from the low band to around 3 kHz, and after 3 kHz 3 compared with Fig. 24 (b). Sound pressure level is falling quickly. The loudspeaker characteristics shown in Figure 2 3 are even better than those in Figure 2 2. Regarding the speaker characteristics shown in Fig. 24, it can be seen that in the time domain of Fig. 24 (a), there are many direct sounds and reflected sounds with large sound pressure, and they reach the sound receiving point. Large direct and reflected sounds diminish with time, resulting in a diffuse sound field. In the frequency range in Fig. 2 4 (b), the sound pressure rises a little near 1 kHz, and then the sound pressure level gradually decreases from the low to the middle to high range. Therefore, for another car (trade name: Corolla), the speaker characteristics due to the speakers 9 2 and 9 2 installed in the conventional position as shown in FIG. 21 are inferior to those in FIG. There is.

Judging from the sound diagram shown in Figure 19 to Figure 21, the measured values shown in Figure 22 to Figure 24, and further listening, the direct sound from the speakers 8 4 and 8 4 under the seat in Figure 19 is Not reach the listener directly, the diffraction sound has reached the ear first. After a short time, the direct sound that moved forward to the foot of the seat reaches the sound receiving point as a reflected sound. As this reflection sound is repeatedly reflected in the space of the foot, each reflection sound is received one after another As it reaches the sound point, it will localize a firm sound image in front of the seat feet

. Also in the frequency response, it is a flat characteristic from low frequency range to about 3 kHz, and in the high frequency range of 3 kHz or more, the level drops quickly, so the bass region is enough for the ear. It forms a sound field played back. By positioning the virtual sound images 90 and 90 in front of the front seats, it is possible to feel the sound of the arranged music hall and listening room instead of the sounds being disorderly. Since the direct sound from the spy force does not reach the listener directly, it is released from the pressure of the sound and a soft and tired sound field is formed. Under the dashboard in Figure 20, the effect is almost the same, except that part of the direct sound from Spy force 9 1, 9 1 arrives at the listener.

In general, temporal acoustic characteristics such as an auditorium or a concert hall are such that the sound played on the stage first reaches the audience directly, then the primary reflection, the secondary reflection, the tertiary reflection, and so on. The sound is transmitted to the audience in a form that supports the volume of the sound, and this makes for a rich volume, a sense of clarity, and a feeling of being surrounded by the sound. Odetrim creates such an acoustic space. In a car, because the acoustic space is small and the reflection distance is short, direct sound, primary reflection sound, secondary reflection sound, etc. reach at the same time to people in the car, and people in the car reach at the same time Will receive high sound pressure at one time. .

On the other hand, as shown in Fig. 19, when spy forces 8 4 and 8 4 are placed under the seat, the person inside the car can see the reflected sound as a virtual sound image instead of the direct sound from both speakers becoming slightly lower. By creating 90, the primary reflection sounds like a direct sound, creating a pseudo-space in which a small space is greatly expanded, and almost the same as in Figure 20. Therefore, even in a car, it is possible to create an acoustic space with temporal acoustic characteristics such as an audio terminal or a concert hall. -On the other hand, in the conventional position shown in Fig. 21, the direct sound from the speakers 9 2 and 9 2 and the reflected sound from it generate a large sound pressure in the car without time intervals. Therefore, the sound from the chaotic direction is engulfed, and the localization of the sound image can not but be determined as difficult. Also in the frequency characteristic, a level rise in the vicinity of 1 to 2 kHz is observed, forming an offensive sound field. From this result, it was found that the speed using damping metal baffle plate etc. Placing the force under the seat or under the dash pad as shown in Figure 19 and Figure 20 can be interpreted as having an excellent effect of improving the sound field in the car. Industrial applicability

The general-purpose speaker according to the present invention absorbs frame vibration of a speed force sensor at the time of signal input by using a rigid vibration-damping metal with high vibration damping property for the speaker unit, baffle plate or mounting member, The film surface of cone paper can be acoustically vibrated precisely. Moreover, when a damping sintered metal such as a porous sintered body intervenes, unnecessary frame vibration is not transmitted to the puffle plate and the enclosure, so that the sound is faithfully reproduced with respect to the input signal, and the bass range and the super range are enhanced. The bass region can be clearly reproduced, and a clearer, sharper sound will be reproduced. In the loudspeaker of the present invention, in particular, the tendency is conspicuous around the listening frequency, and the sound pressure level in the low range is further increased.

In the general-purpose speaker according to the present invention, when two speaker units are fixed in series, the signal is simultaneously input to the front and rear speaker units in the same phase, so the film surface of the cone sheet of the front speaker unit is the rear speaker unit. Vibrates more smoothly in response to the acoustic vibration of the film surface of the cone paper. As a result, the speaker equipped with two speaker units in series is more stable in sound pressure level rise and frequency characteristics in the lower range than the speaker of single unit.

According to the spy force attachment method of the present invention, the conventional in-vehicle sound field is a space of unordered sound by installing the speakers under the driver's seat and the passenger's seat or under the dashboard in the car. On the contrary, position the sound image in front of the front seat and achieve improvement of the sound field like a planned music hall or listening room. Also, in the method of the present invention, the direct sound does not reach the listener directly, and the sound diffused from the front reaches so that a relaxing sound field space without pressure feeling is created.

Claims

The scope of the claims

1. An electromechanical transducer that converts an acoustic output signal into vibration of a vibrator, an acoustic radiation unit that radiates vibration of the vibrator as a sound wave, and a substantially conical damping that is fixed to the transducer and surrounds the acoustic radiation unit A general-purpose speaker consisting of a speaker unit consisting of a metal frame and at least one speaker unit built into a cabinet via a baffle plate, in which the damping metal of the frame has a vibration damping ratio of 0.10 1 Sound reproduction and low frequency range by absorbing the mechanical vibration generated by the transducer with the frame of the single unit with the physical properties above and yang rate of 5.0 x 10 ⁹ NZm ² or more. General-purpose speaker that clearly reproduces the music.

2. The speaker according to claim 1, wherein in the frame of the speaker unit, only the flange portion of the frame is made of damping metal.

3. An electromechanical transducer for converting an acoustic output signal into a vibration of a vibrator, a sound emitting unit for radiating the vibration of the vibrator as a sound wave, a substantially conical frame fixed to the transducer and surrounding the sound emitting unit This is a general-purpose speaker that consists of a speaker unit by mounting the frame of the speaker unit on a vibration-proof metal baffle plate and incorporating at least one speaker unit into the cabinet via a baffle plate. The damping metal of the plate has physical properties of vibration damping factor of 0.1 or more and Young's modulus of 5.0 x 10 ⁹ NZ m ² or more, and the mechanical plate transmitted to the frame of the loudspeaker system is absorbed by the baffle plate This is a general-purpose spear force that reproduces faithfully the acoustic signal and clearly reproduces the low range.

4. An electromechanical transducer for converting an acoustic output signal to vibration of a vibrator, a sound emitting unit for radiating vibration of the vibrator as a sound wave, a substantially conical frame fixed to the transducer and surrounding the sound emitting unit To form a speaker display, with a damping metal mounting member interposed between the speaker and the baffle plate or between the baffle and the cabinet, and at least one speaker unit through the baffle plate. A general-purpose speaker incorporated in a cabinet, wherein the damping metal of the mounting member has physical properties such as a vibration damping ratio of 0.1 or more and a Young's modulus of 5.0 × 10 ⁹ NZm ² or more; Absorption of mechanical vibration that is transmitted to the More general-purpose speaker that faithfully reproduces the acoustic signal and clearly reproduces the low range.

5. An acoustic lens mounted on the front of the speaker is provided, and the acoustic lens is made of a coarse metal foam having a thickness of several mm, and the metal foam is plastically deformed in a convex shape to control the intensity distribution and phase of the sound source. The general-purpose speaker according to claim 1, 3 or 2, wherein the directivity of the generated sound is appropriately diffused. ,

6. The damping metal is a porous sintered body in which the pores on the outer surface are sparse and the pores inside are dense, Fe-A 1 damping alloy or A 1 _ Si damping alloy. The speaker of 1, 3 or 4.

7. The speaker according to claim 1, 3 or 4, wherein the damping metal has a physical property of vibration damping factor of 0.3 or more and Young's modulus of 7.0 × 10 ⁹ NZm ² or more.

8. A speaker unit on which the sound output signal of the amplifier acts, a puffle plate to which the frame of the speaker unit is attached, an acoustic lens mounted on the front of the speaker, and a baffle plate to constitute a speaker box to provide at least one speaker And the acoustic lens is made of a metal form with a thickness of several mm, and the metal form is plastically deformed in a convex shape to control the intensity distribution and phase of the sound source. , General-purpose speaker to diffuse the directivity of the generated sound appropriately.

9. The speed of claim 1, 3, 4 or 8 wherein two sets of speaker units are incorporated into the cabinet. '

An electromechanical transducer that converts current into vibration of the vibrator, an acoustic radiation unit that radiates vibration of the vibrator as a sound wave, a substantially conical frame fixed to the transducer and surrounding the acoustic radiation unit The speaker unit is composed of a speaker unit, and either the frame or baffle plate or mounting member is made of damping metal, and two speakers with this speaker assembly incorporated into the cabinet via the baffle plate are used for automobiles. The speaker mounting method makes it possible to create a soft sound field, with the audible sound inside the car consisting of almost indirect sound, by downsizing and placing both powers forward under the driver's seat and the passenger's seat of the car.

An electromechanical transducer that converts current into vibration of the vibrator, an acoustic radiation unit that radiates vibration of the vibrator as a sound wave, a substantially conical frame fixed to the transducer and surrounding the acoustic radiation unit The speaker unit consists of the frame, baffle plate, One of the mounts made of damping metal is made of vibration-proof metal, and the two speakers with this splay force integrated into the cabinet through the baffle plate are miniaturized for automobile use, and both splay force is for driver's seat and assistant A speaker attachment method in which the audible sound in the car mainly consists of indirect sound and corresponds to the seat, and is placed backwards under the dash pad, to form a soft sound field.