Stiffening part for an audio speaker casing

Abstract

A stiffening part (25) arranged to be integrated into the interior of a casing (12) of an audio speaker (11) in order to stiffen said casing, the audio speaker also being capable of comprising at least one loudspeaker (18a) mounted on a first face (14) of the casing, the stiffening part comprising a connecting portion, at least one damping support defining a receiving space arranged to receive a damping device (40a) intended to limit vibrations of the loudspeaker, wherein the damping support comprises a plurality of ribs (34) distributed around the receiving space (31), each rib extending in a distinct plane parallel to a depth of the receiving space, the stiffening part being arranged such that, when the enclosure (11) is assembled, the connecting portion interconnects inner walls of a second face (15) of the casing and a third face (16) of the casing opposite each other and both perpendicular to the first face (14), the damping device being positioned in the receiving space, and a rear portion of the loudspeaker abutting the damping device.

Description

[0001] The invention relates to the field of stiffening parts for acoustic speaker enclosures. BACKGROUND OF THE INVENTION

[0002] An enclosure consists of a cabinet and one or more loudspeakers. One or more sides of the cabinet include one or more openings, each designed to accommodate a loudspeaker.

[0003] In an acoustic enclosure, the movement of the speaker membranes causes vibrations which produce parasitic noise.

[0004] In reference to the figures 1 et 2 , a prior art enclosure 1 comprises a box 2 having an upper face, a lower face and side faces. The enclosure further comprises a first loudspeaker 3a mounted on the upper face and a second loudspeaker 3b mounted on the lower face of the box 2. The operation of the loudspeakers 3 excites three vibration modes of the enclosure 1.

[0005] A first vibration mode results from a pumping movement of the magnets 4 of the loudspeakers 3. The magnet 4 of each loudspeaker 3 undergoes a translational movement along the translation axis X1 (see figure 1 ) which is a longitudinal axis of the enclosure 1. This translational movement is due to the relatively large mass of the magnet 4 and the relative flexibility of the sheet metal 5 of the loudspeaker 3 called the “salad bowl”, in which the membrane (not shown) extends. The translational movement occurs in the direction of operation of the membrane of the loudspeaker 3.

[0006] A second mode of vibration results from a pendulum movement of the magnets 4 of the loudspeakers 3. The magnet 4 of each loudspeaker 3 undergoes a rotational movement around a pendulum axis X2 which passes through the center of the membrane and which is perpendicular to the longitudinal axis of the loudspeaker 3 (see figure 2 ). This rotational movement is also due to the relatively large mass of the magnet 4 and the relative flexibility of the sheet metal of the loudspeaker 3.

[0007] A third mode of vibration results from a deformation of the box 2 of the speaker 1, which “swells” due to the increase in internal pressure induced by the displacement of the membranes of the loudspeakers 3.

[0008] Document FR 2 746 246 A1 discloses in a certain context a solution for reducing vibration and parasitic noise of an acoustic enclosure. However, this solution does not solve a large part of the problem and, therefore, is far from perfect. SUBJECT OF THE INVENTION

[0009] The invention aims to reduce vibrations and therefore parasitic noise from an acoustic enclosure. SUMMARY OF THE INVENTION

[0010] In order to achieve this aim, a stiffening part is proposed which is arranged to be integrated inside a box of an acoustic enclosure to stiffen said box, the acoustic enclosure being able to further comprise at least one loudspeaker mounted on a first face of the box, the stiffening part comprising a connecting portion, at least one damping support defining a receiving space arranged to receive a damping device intended to limit vibrations of the loudspeaker, the damping support comprising a plurality of ribs distributed around the receiving space, each rib extending in a separate plane parallel to a depth of the receiving space, the stiffening part being arranged so that, when the enclosure is assembled,the connecting portion connects together internal walls of a second face of the box and a third face of the box opposite each other and both perpendicular to the first face, the damping device is positioned in the receiving space, and a rear part of the loudspeaker comes to bear against the damping device.

[0011] The connecting portion that connects the second face and the third face of the box, the ribs and the damping device positioned in the receiving space make it possible to limit the vibrations that have just been mentioned. Thanks to the stiffening part according to the invention, the three main resonance frequencies of the enclosure are moved outside the range of use of the loudspeaker, and the parasitic noises are reduced very significantly.

[0012] We also propose an enclosure comprising a box, a loudspeaker, the stiffening part which has just been described, and a damping device.

[0013] The invention will be better understood in light of the following description of a particular, non-limiting embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Reference will be made to the attached drawings, including: [ Fig. 1 ] there figure 1 is a perspective view of a box and two loudspeakers of a speaker according to the prior art, the view being cut in a plane parallel to a longitudinal axis of the speaker; [ Fig. 2 ] there figure 2 is a view analogous to that of the figure 1 , one of the two loudspeakers undergoing a rocking movement; [ Fig. 3 ] there figure 3 is a perspective view of an enclosure comprising a box, two loudspeakers, two damping devices, and a stiffening part according to the invention; [ Fig. 4 ] there figure 4 is a view similar to that of the figure 3 , the view being cut in a plane parallel to a longitudinal axis of the enclosure; [ Fig. 5 ] there figure 5 is a perspective view of the stiffening part according to the invention; [ Fig. 6 ] there figure 6 is a perspective view of a damping device. DETAILED DESCRIPTION OF THE INVENTION

[0015] In reference to the figures 3 And 4 , the invention is here implemented in an acoustic enclosure 11 which is in this case a connected enclosure.

[0016] The enclosure 11 firstly comprises a box 12 and a plurality of loudspeakers.

[0017] The box 12 has a generally parallelepiped external shape. The box 12 comprises an upper face, here called first face 14, four lateral faces, among which there are two opposite faces (i.e. located one opposite the other) here called second face 15 and third face 16, and a lower face, here called fourth face 17.

[0018] Thus, the first face 14 and the fourth face 17 are two opposite faces which are both perpendicular to the second face 15 and the third face 16.

[0019] Here we call the "longitudinal axis of the box" the axis X3 which passes through the center of the first face 14 and the fourth face 17.

[0020] The plurality of speakers includes a first speaker 18a and a second speaker 18b, as well as other speakers which will not be described herein.

[0021] The first loudspeaker 18a and the second loudspeaker 18b here each comprise a membrane 19, a sheet 20 called a “salad bowl” in which the membrane 19 extends, a coil and a magnet 21. Each magnet 21 here has a truncated cone shape whose radius decreases towards the rear of the loudspeaker 18. Here, the “front part” of each loudspeaker 18 refers to the part which comprises the membrane 19, and the “rear part” refers to the part on the side opposite the membrane 19. The rear part therefore here comprises the magnet 21. Here, the “longitudinal axis of the loudspeaker” X4 refers to the axis of revolution of the magnet 21, which also passes through the center of the membrane 19, and the “height” of the loudspeaker 18 refers to the dimension of the loudspeaker 18 along its longitudinal axis X4.

[0022] The first loudspeaker 18a is mounted on the first face 14 of the box 12. The first loudspeaker 18a is fixed to the first face 14, the longitudinal axis X4 of the first loudspeaker 18a being perpendicular to the first face 14. The first face 14 has an opening whose shape coincides with the circumference of the large diameter of the membrane 19 of the first loudspeaker 18a and into which the membrane 19 opens.

[0023] The second loudspeaker 18b is mounted in the same way on the fourth face 17 of the box 12.

[0024] The first loudspeaker 18a and the second loudspeaker 18b are therefore mounted head to tail in the box 12, and their longitudinal axes X4 are coincident. The longitudinal axes X4 of the first loudspeaker 18a and the second loudspeaker 18b are parallel with the longitudinal axis X3 of the box 12.

[0025] In reference to the figure 5 , the enclosure also includes a stiffening part 25 integrated inside the box 12.

[0026] The stiffening piece 25 is positioned between the first loudspeaker 18a and the second loudspeaker 18b.

[0027] The stiffening part 25 is made of a thermoplastic material.

[0028] The stiffening part 25 firstly comprises a connecting portion 26 (which could also be called a “beam”).

[0029] The connecting portion 26 connects the internal wall of the second face 15 and the internal wall of the third face 16 to each other. The connecting portion 26 extends lengthwise along a connecting axis X5 which, when the stiffening part 25 is positioned in the box 12, is parallel to a transverse axis of the box 12 and is orthogonal to the longitudinal axis X3 of the box 12. The connecting portion therefore extends parallel to the first face 14 and to the fourth face 17 of the box 12.

[0030] The connecting portion 26 here comprises a first end 27 and a second end 28 each provided with means for fixing to a face of the box 12, in this case a thread 29. The first end 27 of the connecting portion 26 is fixed by screwing to the second face 15 of the box 12, while the second end 28 of the connecting portion 26 is fixed by screwing to the third face 16 of the box 12. A first screw 38 (visible on the figure 4 ) thus extends through the second face 15 to be screwed into the thread 29 of the first end 27, and a second screw 38 extends through the third face 16 to be screwed into the thread 29 of the second end 28 of the connecting portion 26.

[0031] The stiffening part 25 further comprises a first damping support 30a and a second damping support 30b.

[0032] The first damping support 30a and the second damping support 30b are located at a central portion of the connecting portion 26.

[0033] First, the first damping support 30a is described.

[0034] The first damping support 30a defines a receiving space 31 having a general shape of revolution, in this case a truncated cone shape. The axis of revolution X6 of the receiving space 31 is orthogonal to the connecting axis X5 of the connecting portion 26.

[0035] The radius of the reception space 31 is reduced at a bottom 32 of the reception space 31, and increases up to the main opening of the reception space 31, which extends opposite the bottom 32 of the reception space 31.

[0036] The first damping support 30a comprises ribs 34 which are distributed, with a different orientation, around the receiving space 31. The ribs 34 each have the shape of a fin. The ribs 34 extend radially around the receiving space 31 from the circumference of the receiving space 31. The length of each rib is parallel to the axis of revolution X6 of the receiving space 31, and the width of each rib 34 is defined in the extension of the radius of the receiving space 31. Each rib 34 extends in a separate plane parallel to a depth of the receiving space 31, that is to say here to the axis of revolution X6 of the receiving space 31.

[0037] Each rib 34 comprises a base 35, located at the bottom 32 of the receiving space 31, and a free end 36. Each rib 34 has a notch 37 formed opposite the receiving space 31, so that the width of each rib 34 decreases from the base 35 of the rib 34 to the free end 36 of the rib 34. The truncated cone shape of the receiving space 31 is defined by the notches 37 formed in the ribs 34.

[0038] The second damping support 30b has the same shape as the first damping support 30a. The receiving space 31 of the first damping support 30a and that of the second damping support 30b have a coincident axis of revolution X6, so that, looking along this axis of revolution X6, the first damping support 30a and the second damping support 30b are superimposed. The ribs 34 of the first damping support 30a are defined in continuity and in the extension of the ribs 34 of the second damping support 30b: these are the same ribs 34 which each comprise a half of a rib belonging to the first damping support 30a and a half of a rib belonging to the second damping support 30b.

[0039] The first damping support 30a and the second damping support 30b are however arranged head to tail, on either side of the connecting axis X5 of the connecting portion 26: the bottom 32 of the receiving space 31 of the first damping support 30a is located against or at least close to the bottom of the receiving space 31 of the second damping support 30b.

[0040] The receiving space 31 of the first damping support 30a is intended to receive a damping device 40a, and the receiving space 31 of the second damping support 30b is intended to receive a damping device 40b.

[0041] Each damping device 40 is made of a flexible material, here an elastomeric material.

[0042] In reference to the figure 6, each damping device 40 has a truncated external shape, and has a relatively small thickness. The large radius face 41 of the damping device 40 is completely open, while the small radius face 42 of the damping device 40 is partially closed while having a central opening 43. The central opening 43 allows the suction and evacuation of the air masses displaced by the movement of the membrane 19.

[0043] The assembly of the enclosure 11 is carried out in the following manner. The stiffening part 25 is screwed into the box 12. A damping device 40a is arranged in the receiving space 31 of the first damping support 30a. A damping device 40b is arranged in the receiving space 31 of the second damping support 30b. The first loudspeaker 18a is fixed to the first face 14 of the box 12 and the second loudspeaker 18b is fixed to the fourth face 17 of the box 12. Then, the first loudspeaker 18a, the first face 14, the second loudspeaker 18b and the fourth face 17 are mounted on the rest of the box 12.

[0044] When the enclosure 11 is assembled, the connecting portion 26 of the stiffening piece 25 connects the internal walls of the second face 15 of the box 12 and the third face 16 of the box 12 together. The rear part of the first loudspeaker 18a bears against the damping device 40a positioned in the receiving space 31 of the first damping support 30a. The rear part of the second loudspeaker 18b bears against the damping device 40b positioned in the receiving space 31 of the second damping support 30b.

[0045] The ribs 34 of the first damping support 30a and the ribs 34 of the second damping support 30b are all perpendicular to the first face 14 and to the fourth face 17 of the box 12, and are all parallel to the longitudinal axis X3 of the box 12.

[0046] The stiffening part 25, which is fixed in the box 12 at its ends, makes it possible to stiffen the box 12.

[0047] The stiffening part 25 is structured by the ribs 34 which also stiffen the box 12. The ribs 34 prevent deformations by swelling of the box 12 caused by variations in internal pressure due to the displacement of the membranes 19 of the first loudspeaker 18a and the second loudspeaker 18b.

[0048] The damping devices 40, for their part, significantly limit the pumping of the magnets 21 of the first loudspeaker 18a and of the second loudspeaker 18b, i.e. the translational movement of the magnets 21. The damping devices 40 also significantly limit the swing of the magnets 21 around the swing axis X2.

[0049] The use of the stiffening part 25 thus makes it possible to move the three main resonance frequencies of the enclosure 11 outside the range of use of the first loudspeaker 18a and the second loudspeaker 18b (and the other loudspeakers of the enclosure 11), that is to say here beyond 300Hz. The stiffening part 25 therefore makes it possible, with a simple assembly of a plastic part and two elastomer washers, to eliminate the sources of vibration of the enclosure 11 causing parasitic noise.

[0050] It is noted that the stiffening part 25 comprises a plurality of card supports 43. Each card support 43 comprises a flat surface 44 of rectangular shape and four corners 45.

[0051] In particular, there is a first card support 43a located at the first end 27 of the connecting portion 26 and a second card support 43b located at the second end 28 of the connecting portion 26.

[0052] When the stiffening part 25 is mounted in the box 12, the flat surface 44 of the first card support 43a is parallel to the second face 15 of the box 12 and is located opposite and close to the second face 15. The flat surface 44 of the second card support 43b is parallel to the third face 16 of the box 12 and is located opposite and close to the third face 16.

[0053] The first card holder 43a is arranged to accommodate a first electrical card 46a, which is positioned against the flat surface 44 of the first card holder 43a while being held in position between the four corners 45. The first electrical card is fixed to the first card holder 43a.

[0054] The first 46a electrical board here includes a Wi-Fi antenna which does not interact with the speakers.

[0055] The second card holder 43b is arranged to accommodate a second electrical card 46b, which is positioned against the flat surface 44 of the second card holder 43b while being held in position between the four corners 45. The second electrical card 46b is fixed to the second card holder 43b.

[0056] The second 46b electrical board here includes a Wi-Fi antenna which does not interact with the speakers.

[0057] There is also a third card support 43c positioned at the central part of the connecting portion 26.

[0058] Grooves 48 are formed on the damping supports 30 of the stiffening part 25. Electrical wires connected to the first electrical card 46a and to the second electrical card 46b run in the grooves 48. The grooves 48 make it possible to both hold these electrical wires in position and protect them.

[0059] Thus, it can be seen that, in addition to its role of stiffening and supporting the damping devices 40, the stiffening part 26 makes it possible to integrate and protect, in a clever and inexpensive manner, electrical cards 46 and wires inside the box 12.

[0060] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0061] The speaker(s) that cooperate with the stiffening piece are not necessarily mounted on an upper or lower face of the box.

[0062] The shape of the elements described could be different. In particular, the magnet of each speaker could have a different shape (annular, cylindrical, etc.), as could the space for receiving each support.

[0063] The rear part of the speaker, which is in contact with the damping device, is not necessarily the magnet, but can be any element located at the rear of the speaker: part of the motor, part attached to the basket, etc.

[0064] The damping device(s) may be different from those described herein. The damping devices could be integrated into the stiffening part, for example by being manufactured by overmolding.

[0065] The stiffening part could belong to the box and form a single part with the box (or at least with the second face and / or the third face of the box). It should also be noted that, when we say that the connecting portion connects the internal walls of the second face of the box and the third face of the box, we do not necessarily mean that the connecting portion is directly fixed to the internal walls: the connecting portion could be fixed to any parts which are themselves integral with the internal walls.

Claims

1. A stiffener part (25) arranged to be incorporated inside a cabinet (12) of a speaker enclosure (11) in order to stiffen said cabinet, the speaker enclosure also being capable of containing at least one loudspeaker (18a) mounted against a first face (14) of the cabinet, the stiffener part comprising a connection portion (26) and at least one damper support (30a) defining a reception space (31) arranged to receive a damper device (40a) for limiting vibration of the loudspeaker, the damper support comprising a plurality of splines (34) distributed around the reception space (31), each spline extending in a distinct plane parallel to a depth dimension of the reception space, the stiffener part being arranged in such a manner that, when the enclosure (11) is assembled, the connection portion (26) connects together inside walls of mutually opposite second and third faces (15, 16) of the cabinet that are both perpendicular to the first face (14), the damper device is positioned in the reception space, and a rear portion of the loudspeaker comes to bear against the damper device.

2. A stiffener part according to claim 1, wherein the reception space (31) presents the general shape of a volume of revolution, and wherein the splines (34) project radially around the reception space.

3. A stiffener part according to any preceding claim, wherein each spline (34) is in the form of a fin.

4. A stiffener part according to any preceding claim, wherein the shape of the reception space (31) is defined by setbacks (37) formed in the splines and facing the reception space.

5. A stiffener part according to any preceding claim, wherein each spline (34) presents a width that decreases between a base (35) of the spline and a free end (36) of the spline, such that the reception space (31) presents a shape that is frustoconical.

6. A stiffener part according to any preceding claim, wherein the connection portion presents two ends that include respective fastener means (29) for fastening the stiffener part (25) to the second and third faces (15, 16) of the cabinet.

7. A stiffener part according to any preceding claim, the stiffener part being made out of a thermoplastic material.

8. A stiffener part according to any preceding claim, the enclosure being capable of containing at least a first loudspeaker (18a) mounted against the first face (14) of the cabinet and a second loudspeaker (18b) mounted against a fourth face (17) of the cabinet that is opposite the first face, the first and second loudspeakers being mounted back-to-back, the stiffener part including a first damper support (30a) and a second damper support (30b) that are arranged back-to-back.

9. A stiffener part according to any preceding claim, and further comprising at least one card support (43a) on which an electric circuit card (46a) can be fastened.

10. A stiffener part according to claim 9, having two card supports, each presenting a respective plane surface (44) and each being situated at a respective end of the connection portion (26).

11. A stiffener part according to claim 9, further including grooves (48) arranged so that wires connected to the electric card pass along the grooves.

12. An enclosure comprising a cabinet, a loudspeaker, a stiffener part according to any preceding claim, and a damper device (40).

13. An enclosure according to claim 12, wherein the damper device (40) is made out of an elastomer material.

14. An enclosure according to claim 12, comprising a stiffener part (25) according to claim 8, a first loudspeaker (18a) mounted against a first face of the cabinet, a second loudspeaker (18b) mounted against a fourth face of the cabinet, together with two damper devices, the first loudspeaker and the second loudspeaker being mounted back-to-back in the enclosure.

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