FR2818083A1 - Electro acoustic loudspeaker having housing with vibrating membrane formed with outer bowl compression chamber attached one end and other end attached moving coil spider section. - Google Patents

Abstract

The loudspeaker has internal housing concentrating sound waves and deadening acoustic pressures. There is a housing (11) with an outer bowl unit (0) and a vibrating membrane (1). There is an optimal size compression chamber (12). The housing and compression chamber are connected to the bowl at one end, and form a calibrated opening (13) at the other end for the moving coil (7), being attached to the front of a spider section (8). A principal load deadening area is defined (VC).

Description

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 The present invention relates to an internal horn acoustic device for an electroacoustic loudspeaker Charged by an enclosure, making it possible to concentrate the sound waves, while promoting the damping of the acoustic pressures.

 In the current technique, the acoustic horns are formed from a duct with a conical, exponential, or hyperbolic profile.

In general, these horns incorporate a compression chamber, formed between the body of the horn and the front face of the loudspeaker, the rear face of the loudspeaker being loaded by a closed or open volume of the "Bass-Reflex" type.

There are also enclosures similar to the aforementioned pavilions, called "pavilion initiation enclosures", where only the rear face of the loudspeaker is loaded by a folded back pavilion forming the box; The latter, given their designs, do not provide the expected benefits.

 The role of an acoustic horn is to improve the coupling between the cone (vibrating membrane) of the loudspeaker and the ambient air.

de l'ensemble. (Pavillon = Transformateur d'Impédance Acoustique). Compression chamber increases sound pressure

from the whole. (Pavilion = Acoustic Impedance Transformer).

The disadvantages of the classic pavilion are quite negligible.

The colors due to the "megaphone" effect or the directivity are not real faults compared to the advantages provided.

The excellent performance or the very low excursions of the mobile crew are the essential points.

 On the other hand, the horn systems for Low frequency do not give all satisfactions, ensuring a good performance in the Low-Medium, but quickly becoming faulty in the low end of the sound spectrum. equal dimensions, the results obtained with "Bass-Reflex" speakers with direct radiation, are often superior.

 This problem is a consequence of an essential fact which relates directly to the pavilion and to the second Charge which accompanies it.

A conventional horn with a compression chamber forms a real acoustic load which firmly dampens the variations in acoustic pressure produced by the front face of the loudspeaker.

In return, the second Charge of the closed type or "Bass-Reflex",

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procure un amortissement beaucoup moins puissant à la face arrière du haut-parleur, engendrant de ce fait, un déséquilibre dans l'opposition des pressions acoustiques respectives à ces deux Charges.

provides much less powerful damping on the rear face of the loudspeaker, thereby causing an imbalance in the opposition of the respective acoustic pressures to these two loads.

As the two loads do not work in harmony, a malfunction occurs which weakens the whole system.

The device according to the invention provides the solution to these problems.

According to this device, the acoustic enclosure is composed of an electrodynamic loudspeaker which closes by its dorsal face, formed of an openwork bowl, the front opening of a closed box, provided for this purpose.

 According to a first characteristic, a conduit, the expansion of the profile of which forms a pavilion, is placed directly inside the loudspeaker bowl, just behind the cone (vibrating membrane) which emits sounds and forms a very limited internal volume. behind the said sound cone, characteristic of a compression chamber.

This low volume forms a compression chamber at an optimal rate, favoring a high acoustic impedance, the dimensions of which are calculated as a function of the characteristics of the loudspeaker, of the maximum clearance of the moving equipment (Suspensions-Cone-Coil).

 The pavilion generally takes up the shape and profile of the cone.

Its section may be round, square, elliptical, and its profile, conical, exponential, or hyperbolic.

 The part "large opening" of the pavilion (side where the section is the largest), is attached in a contiguous manner to the internal part of the bowl, corresponding to the crown of the bowl supporting the external peripheral suspension of the cone.

 The "small opening" part of the pavilion (side where the section is the smallest) is not fixed to the bottom of the bowl.

This part forms a calibrated opening which opens around the joint formed by the cone and the cylindrical support of the voice coil, just before the internal spider suspension of the cone.

This more or less flared opening forms the neck of the pavilion and opens, through the perforated bowl, into the volume of the main load of the enclosure formed by a closed box.

The main load volume, constitutes the volume of acoustic damping, whose more or less important value is

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conséquente d'une certaine" élasticité". e
Les dimensions de l'ouverture (calibrée) du col du pavillon, qui forme un passage de régulation des pressions et dépressions acoustiques entre la chambre de compression et le volume de Charge principal, sont définies par les paramètres des éléments suivants : - Haut-Parleur + Chambre de Compression = Goulot de Compression.

consequent of a certain "elasticity". e
The dimensions of the (calibrated) opening of the roof neck, which forms a passage for regulating the acoustic pressures and depressions between the compression chamber and the main load volume, are defined by the parameters of the following elements: - Loudspeaker + Compression Chamber = Compression neck.

 - Compression neck / Main Load Volume.

The neck of the roof (calibrated opening) forms a constant "acoustic mass", compared to the "acoustic elasticity" presented by the volume of main load.

 The horn forms an element in solid and rigid material, made of the same material as that of the salad bowl or that of the sound cone.

The pavilion can be molded directly into the bowl itself. (fig 1)
According to a particular embodiment, the horn is placed in front of the front face of the loudspeaker, in a coaxial manner, and generally takes up the shape and the profile of the cone emitting sounds.

For this, the loudspeaker is fixed upside down; its front face provided with the flag, closes the traditional anterior opening of the enclosure provided for this purpose; its rear side, on the motor magnet side, is visible and radiates the Sounds directly into the ambient air through the perforated bowl.

The part of the section of the pavilion "large opening side" is attached so as to join the part of the crown of the bowl supporting the external peripheral suspension of the cone.

The front face of the cone (not visible given the position of the loudspeaker) forms with the roof, the compression chamber.

The acoustic pressures produced in the compression chamber are evacuated to the main load volume of the enclosure through a calibrated opening, formed by the section of the horn section "small opening side"; this calibrated opening forming the neck of the pavilion, is located in the center of the sound emitting cone, near the central core dome of said cone. (fig 2)
Always according to this realization, but according to a difference of constitution, the section of the pavilion "side small opening" is closed on itself.

 Acoustic pressures produced in the compression chamber

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sont évacuées vers le volume de Charge principal de l'enceinte par plusieurs petites ouvertures calibrées, disposées de façon équilibrée sur l'ensemble du conduit formant le pavillon.

are discharged to the main load volume of the enclosure by several small calibrated openings, arranged in a balanced manner over the entire duct forming the pavilion.

All of these openings form the collar of the pavilion.

 According to another embodiment, and according to the configuration first exposed, the pavilion is fixed contiguously inside the bowl, on either side of its two sections.

The part of the section of the pavilion "large opening side" being always fixed to the internal part of the bowl corresponding to the crown of said bowl, the part of the section of the pavilion "small opening side! Being fixed to the bottom of the bowl, at the part of the chassis supporting the internal suspension (spider).

The acoustic pressures produced in the compression chamber are evacuated to the main load volume of the enclosure by several small calibrated openings, arranged in a balanced manner on the upper part of the pavilion "side large opening", opposite and opposite the external peripheral suspension.

All of these openings form the collar of the pavilion. (fig 3)
According to another embodiment, and according to a specific construction of the loudspeaker, the dorsal part of the loudspeaker constitutes directly the flag, the salad bowl not being perforated, but provided with calibrated openings.

The volume forming the compression chamber is between the rear face of the cone and the rear face of the bowl.

The acoustic pressures produced in the compression chamber are evacuated to the main load volume of the enclosure by several small calibrated openings, arranged in a balanced manner over the entire bowl forming the pavilion.

All of these openings form the collar of the pavilion. (fig 4)
According to a complementary embodiment, each calibrated opening is profiled towards the outside of the bowl, forming an expansion of the neck of the pavilion, a pre-compression tunnel.

This tunnel, more or less flared, takes the shape of the emitting cone of Sounds: (H-P round = cylindrical tunnel).

The length of this tunnel, which defines the pre-compression volume, is calculated according to the parameters of the compression chamber,

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compared to those of the main Load volume. (fig 5)
According to a different embodiment, the pavilion is held in the bowl, on either side of its two sections, by two rubber rings (silentbloc) more or less elastic.

Le pavillon"mobile"est constitué d'un cône identique à celui du cône émetteur de Sons ; il est disposé à la file, de façon coaxiale et forme une chambre de compression compacte et équilibrée, dont le volume est calculé suivant l'élasticité et le débattement respectif des suspensions des dits cônes. According to the previous embodiment, the pavilion is provided with suspensions identical to those of the sound emitting cone; these suspensions which hold the flag, are placed inside the bowl, opposite or jointly from those of the sound cone.

The "mobile" pavilion consists of a cone identical to that of the sound emitting cone; it is arranged in a line, coaxially and forms a compact and balanced compression chamber, the volume of which is calculated according to the elasticity and the respective deflection of the suspensions of the said cones.

There is no pavilion neck opening; only the acoustic transparency of the "passive" cone forming the flag, makes it possible to obtain a damping of the acoustic waves through the said "passive" cone, Loaded by the main volume of the enclosure. (fig 6)
The accompanying drawings illustrate, by way of example, various possibilities for carrying out the invention.

 Figure 1 shows in section, the device according to the invention.

 Figure 2 shows in section, a variant of the device different by the position of the speaker, which is reversed.

 Figures 3,4, 5, and 6 show in section, variants of this acoustic device. In these figures, only the loudspeaker is shown, without the enclosure (the closed enclosure) forming the main load volume (VC) of said loudspeaker.

 With reference to these drawings, the enclosure according to the device comprises an electrodynamic loudspeaker (0), consisting of an openwork bowl (2), the crown (3) of which forms the front frame of said bowl and supports the peripheral suspension external (4) of the Sound emitting cone (1).

The central part of the cone (1) is hidden by a dome-shaped core cover (5).

The magnetic circuit forms the motor magnet (6), the voice coil (7) of which is supplied by conventional electrical connections, "not shown in the figures presented".

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 The internal "spider" suspension (8) holds and guides the entire moving assembly (Suspensions-Cone-Coil).

The front opening (9) of the box (10) receives the electrodynamic loudspeaker (0); the electrodynamic loudspeaker (0) is provided with an internal horn (11) forming a compression chamber (12) which opens out through a calibrated opening (13), into the main Charge volume (VC) formed by the enclosure (10). The extension of the flag neck can form a pre-compression tunnel (14).

According to the embodiment of Figure 6, the suspensions (4 ') and (8') maintain and guide the flag (11) "mobile".

In the embodiment according to Figure 1, the flag (11), if it is not molded directly to the bowl (2) in light alloy, can be glued (epoxy resin), welded, joined together; only the pavilion neck forms an opening.

Depending on the material used, the pavilion can be acoustically transparent or not, absorbent or non-absorbent.

Example: In metal, plastic, polystyrene, wood, cellulose pulp.

 The loudspeaker is attached contiguously (putty paste) to the front opening (9) of the enclosure (10) provided for this purpose.

 The box constituting the enclosure (10) is made of solid and rigid material, such as wood or wood derivatives (agglomerated), of a correct thickness and density, causing neither tonics nor resonances, so known per se. The box constituting the enclosure (10) is of such shape as Cubic, or parallelepiped, or cylindrical, etc., in a manner known per se.

 According to the embodiment, the electrical connections which supply the voice coil, can pass directly through the opening (or openings) formed by the neck of the pavilion, or through passages studied accordingly, formed for example, in the case of FIG. 6, between the two spiders.

 In FIG. 2, the loudspeaker is provided with an inverted dome core cover (5). This core cover can be removed, thereby enabling excellent ventilation of the voice coil.

 The optimization calculation of the present invention is carried out according to the parameters indicated above.

This calculation must be made taking into account all of the

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forme :"le haut-parleur + la chambre de compression", par rapport au volume de Charge principal de l'enceinte.

form: "the loudspeaker + the compression chamber", in relation to the main load volume of the enclosure.

The load volume of the enclosure can be evaluated by taking the calculation bases for closed enclosures (called enclosures with acoustic suspension) with traditional external pavilion.

The optimization following the pass of the collar will give: - Too large opening = Bad damping, go up from Fr. - Too small opening = Braking action and not damping.

In these two cases, the results will give a poor impulse response, as well as a decrease in Yield.

 The embodiments according to Figures 3,4 and 5, are rather intended for loudspeakers of frequency Medium and Treble with integrated Load, while those of figures 1,2 and 6 are more intended for loudspeakers of Bass frequency.

 Operation: The loudspeaker (H-P) emits sound waves from alternating electrical signals from the amplifier.

The sound waves produced by the rear face of the H-P cone form variations in sound pressure directly in the compression chamber formed by the internal horn.

The optimal compression rate of the said chamber, makes it possible to obtain a high acoustic pressure, favoring a perfect coupling between the cone emitting sounds and the ambient air.

The displacements of the cone are controlled (damped) by opposition of air pressures, limiting all parasitic over-oscillations.

The control of these over-oscillations makes it possible to limit the formation of induced electric current (FCEM) at the level of the motor magnet, thus promoting an almost constant supply current.

In addition, the pavilion forms a direct acoustic screen, which reflects the sound waves emitted by the cone, through the cone itself, the latter being, more or less "acoustically transparent".

 The damping of the strong variations in sound pressure produced in the compression chamber is ensured by the neck of the roof, forming a calibrated opening which opens into the main load volume of the enclosure.

This depreciation incorporates the theory of the following personal invention patents: NO 91 05975-N 91 05976-N 94 14680.

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 The invention presented differs from the previous ones by the use of a neck forming a compression chamber at an optimal rate, with high acoustic impedance.

 The principle of this damping is based on the Helmholtz resonator, which by the use of a resonator composed of a more or less large volume, leading to a more or less narrow neck, allows to reinforce or absorb certain frequencies .

The air contained in the main volume is comparable to a spring, while the air contained in the neck, by the very great speed of the air molecules produced by the narrow passage of the neck, creates a strong resistance, thus forming a certain mass relative to the elasticity of the main volume of the resonator.

 In the present invention, the sound emitting cone and the compression chamber form a common acoustic mass, which constitutes "the acoustic compression neck".

 The calibrated opening of the pavilion, for its part, forms the narrow passage of the neck, and constitutes "the neck".

 The main load volume of the enclosure formed by a closed cabinet constitutes "the elastic volume".

A perfect optimization of these different elements allows to reinforce all the Sounds of the loudspeaker, within the limits of the value of the critical acoustic resistance, which corresponds to the main resonance frequency (Fr) of the whole.

The resonant frequency (Fr) is absorbed by the "acoustic elasticity" of the main load volume of the enclosure.

 According to all of the figures presented, it will be possible to adapt to the loudspeaker, a traditional external acoustic pavilion, the compression chamber of which will be balanced with respect to that formed by the internal pavilion presented.

éférences aux a en références aux dessins annexés, le sont à titre indicatif, et non limitatif, et que de nombreuses modifications peuvent être apportées, sans que l'on s'écarte pour cela de la présente invention.It is understood that the examples given in this file,

References to a with reference to the appended drawings, are for information only, and are not limiting, and that numerous modifications can be made, without departing from the present invention.

Claims (8)

1-Acoustic device with internal horn for electroacoustic loudspeaker Charged by an enclosure, making it possible to concentrate sound waves, while promoting the damping of acoustic pressures, composed of an electrodynamic loudspeaker closing by its dorsal face, formed by '' an openwork bowl, the front opening of a closed box provided for this purpose, characterized in that a duct, the expansion of the profile of which forms a pavilion (11), is placed directly inside the bowl ( 2) of the loudspeaker (0), just behind the cone "vibrating membrane" (1) transmitter of Sounds, and forms a very limited internal volume behind the said sound cone, characteristic of a compression chamber. This low volume forms a compression chamber (12) at an optimal rate, favoring a high acoustic impedance, the dimensions of which are calculated as a function of the characteristics of the loudspeaker (0), of the maximum clearance of the mobile equipment (Suspensions-Cone -Coil). The pavilion (11) forms a solid and rigid element, made of the same material as that of the bowl (2) or that of the sound cone (1). The flag (11) can be directly molded in the bowl itself. The pavilion (11) generally takes up the shape and profile of the cone (1). Its section may be round, square, elliptical, and its profile, conical, exponential, or hyperbolic.  The part "large opening" of the pavilion (side where the section is the largest), is attached in a contiguous manner to the internal part of the bowl (2), corresponding to the crown (3) of the bowl (2) supporting the peripheral suspension outer (4) of the cone (1).  The "small opening" part of the pavilion (side where the section is the smallest) is not fixed to the bottom of the bowl (2). This part forms a calibrated opening (13) which opens around the joint formed by the cone (1) and the cylindrical support of the voice coil (7), just before the internal suspension "spider" (8) of the cone (1 ). This opening (13) more or less flared, forms the neck of the pavilion (11) and opens, through the openwork bowl (2), into the main load volume (VC) of the enclosure (10) formed by a closed box. <Desc / Clms Page number 10>

The main Load volume (VC) constitutes the volume of acoustic damping, the more or less important value of which is due to a certain "elasticity". The dimensions of the "calibrated" opening (13) of the roof neck, which forms a passage for regulating the acoustic pressures and depressions between the compression chamber and the main load volume, are defined by the parameters of the following elements: - Speaker + Compression Chamber = Compression neck. - Compression neck / Main Load Volume. The neck of the roof (calibrated opening) forms a constant "acoustic mass", compared to the "acoustic elasticity" presented by the main Load volume (VC). (Fig 1) 2-Device according to claim 1, characterized in that the horn (11) is placed in front of the front face of the loudspeaker (0), coaxially, and generally takes up the shape and the profile of the cone (1) transmitter of Sounds. For this, the speaker (0) is fixed upside down; its front face provided with the flag (11), closes the traditional front opening (9) of the enclosure (10) provided for this purpose; its rear side, on the motor magnet side (6), is visible and radiates the Sounds directly into the ambient air through the perforated bowl (2). The part of the section of the pavilion "large opening side" is attached so as to join the part of the crown (3) of the bowl (2) supporting the external peripheral suspension (4) of the cone (1). The front face of the cone (1) (not visible given the position of the loudspeaker) forms, with the horn (ll), the compression chamber (12). The acoustic pressures produced in the compression chamber (12) are evacuated to the main load volume (VC) of the enclosure (10) by a calibrated opening (13) formed by the section of the horn section (11) " small opening side "; this calibrated opening (13) forming the neck of the flag (11), is located in the center of the cone (1) which emits sounds, near the central core cover dome (5) of said cone. (Fig 2) 3-Device according to claim 2, characterized in that the section of the pavilion "side small opening" is closed on itself. <Desc / Clms Page number 11>  The acoustic pressures produced in the compression chamber are evacuated to the main load volume of the enclosure by several small calibrated openings arranged in a balanced manner on the whole of the duct forming the pavilion.

All of these openings form the collar of the pavilion. 4-Device according to claim 1, characterized in that the flag (11) is fixed contiguously inside the bowl (2), on either side of its two sections. The part of the section of the pavilion "large opening side" being always attached to the internal part of the bowl (2) corresponding to the crown (3) of said bowl, the part of the section of the pavilion "small opening side" being fixed to the bottom of the bowl (2), to the part of the frame supporting the internal "spider" suspension (8). The acoustic pressures produced in the compression chamber (12) are evacuated to the main load volume of the enclosure by several small calibrated openings (13), arranged in a balanced manner on the upper part of the roof (11) "large opening side ", opposite and opposite the external peripheral suspension (4). All of these openings (13) form the neck of the pavilion. (fig 3) 5-Device according to claim 1 and claim 4 characterized in that and according to a specific construction of the speaker (0), the back part of the speaker (0) directly constitutes the horn (11), the bowl (2 ) not being perforated, but provided with calibrated openings (13). The volume forming the compression chamber (12) is between the rear face of the cone (1) and the rear face of the bowl (2). The acoustic pressures produced in the compression chamber (12) are evacuated to the main load volume of the enclosure by several small calibrated openings (13) arranged in a balanced manner on the whole of the bowl (2) forming the pavilion (11 ). All of these openings (13) form the neck of the pavilion. (fig 4) 6-Device according to any one of the preceding claims, characterized in that each calibrated opening (13) is profiled towards the outside of the bowl (2) forming an expansion of the collar neck (11), a pre-compression tunnel (14). <Desc / Clms Page number 12>  This tunnel (14), more or less flared, takes the shape of the cone (1) which emits sounds: (H-P round = cylindrical tunnel). The length of this tunnel, which defines the pre-compression volume, is calculated according to the parameters of the compression chamber (12) compared to those of the main Load volume (VC). (fig 5) 7-Device according to any one of the preceding claims, characterized in that the flag is held in the bowl, on either side of its two sections, by two rubber rings (silentbloc) more or less elastic.  8-Device according to claim 7, characterized in that the pavilion (11) is provided with suspensions (4 ') (8') identical to those "(4) (8)" of the cone (1) transmitter of Sounds; these suspensions which hold the flag (li), are placed inside the bowl (2), opposite or jointly from those of the sound cone (1).  The mobile horn (11) consists of a cone identical to that of the cone (1) which emits sounds; it is arranged in line, coaxially and forms a compact and balanced compression chamber (12), the volume of which is calculated according to the elasticity and the respective deflection of the suspensions of said cones. There is no pavilion neck opening; only the acoustic transparency of the "passive" cone forming the pavilion (ll) makes it possible to obtain damping of the acoustic waves through the said "passive" cone Loaded by the main volume of the enclosure. (fig 6)

 9-Device according to any one of the preceding claims, characterized in that the box constituting the enclosure (10) is made of solid and rigid material, such as wood or wood derivatives (agglomerated), of a thickness and of a correct density, causing neither tonics nor resonances, in a manner known per se.  10-Device according to any one of the preceding claims, characterized in that the box constituting

 the enclosure (10) "forming the main Load volume (VC)", is of such shape as Cubic, or parallelepipedic, or cylindrical etc ... in a manner known per se.