Speaker frame

Abstract

Chassis (24) for a loudspeaker (20), said loudspeaker (20) being able to be integrated into the box of an enclosure and also being able to comprise a mobile assembly comprising a membrane, the chassis (24) comprising a front face (28) arranged to be positioned at a first face of the box and in which an opening (36) is formed, defined by a periphery (37) to which the membrane can be secured so that the membrane is in acoustic communication with the exterior of the box via the opening, the chassis (24) further comprising a fixing lug (40) which extends from the front face of the chassis towards the rear of the chassis, and which is arranged to be fixed to a second face of the box.

Description

[0001] The invention relates to the field of loudspeakers and, more specifically, to loudspeaker chassis. BACKGROUND OF THE INVENTION

[0002] In reference to the figure 1 , a speaker 0 of the prior art, intended to be integrated into audio equipment, comprises an acoustic box 1 comprising a rear shell 2 and a cover 3 forming a front face of the acoustic box 1. The rear shell 2 defines the internal acoustic volume of the speaker 0, which is closed by the cover 3.

[0003] The enclosure 0 comprises a loudspeaker 4 integrated into the acoustic box 1. The loudspeaker 4 is mounted on the cover 3. The cover 3 comprises an opening 5, and the loudspeaker 4 is integrated into the box 1 so that its membrane 6 is in acoustic communication with the exterior of the box 1 via the opening 5.

[0004] The seal is made between the back shell 2 and the cover 3.

[0005] However, we know that all mechanical parts have natural modes of vibration, called natural modes. Each mode is associated with a specific deformation pattern and a natural frequency, on which a tiny amount of energy will be enough to cause a resonance phenomenon. These modes depend on the mechanical characteristics of the materials used (density, rigidity, compressibility), the shape of the parts and their assembly (contact points, external constraints). They can lead to a degradation of the acoustic performance of the enclosure 0 by generating distortion or even vibrations audible to the user. They can also prematurely damage mechanical or electronic components by generating excessive stresses.

[0006] As regards the box 1, the stiffening of the faces of the shell 2 is ensured by ribs 7 present on the internal walls of the shell 2. These ribs 7 are formed in the direction of demolding of the shell 2. Similarly, the cover 3 can be stiffened using ribs or screws 8 fixing the cover 3 to the shell 2, so that the cover 3 is non-deformable in the direction of movement of the membrane 6 of the loudspeaker 4.

[0007] However, the speaker 4 is not necessarily mounted on the cover 3 and can be fixed on a “side” face of the shell 2.

[0008] We see on the figures 2 et 3 an enclosure 10 in which the loudspeaker 11 (only the chassis is shown) is fixed not on the cover 12 but on the upper face 13 of the shell 14 of the box 15 defining the acoustic volume. The choice of the positioning of the loudspeaker 11 results for example from mechanical and assembly constraints.

[0009] It is impossible to rib the upper face 13 in the direction of movement of the membrane of the loudspeaker 11 (not shown), because this would prevent the part from being demolded. The addition of the mass of the magnet of the loudspeaker 11 cantilevered relative to its fixings and the absence of reinforcements then modify the dynamic behavior of the box 15 of the speaker 10: the natural modes of the latter lead to a significant displacement of the upper face 13 in the direction of movement of the membrane. The energy provided by the loudspeaker 11 is therefore not negligible and these modes have a very high probability of being excited.

[0010] This arrangement therefore risks leading to significant deformations.

[0011] This is clearly visible on the figures 4 et 5 In these figures, the hatching represents the levels of deformation: the tighter the hatching, the higher the levels.

[0012] The natural mode of the box 15 of the enclosure 10 has a maximum displacement corresponding to the vibration antinode 17 formed at the end of the upper face 13 on which the loudspeaker 11 is fixed, and on which the cover 12 rests, with a main component along the axis y . SUBJECT OF THE INVENTION

[0013] The invention relates to a solution for stiffening the faces of the box of a speaker incorporating a loudspeaker to limit their deformation during operation of the loudspeaker. SUMMARY OF THE INVENTION

[0014] To achieve this goal, a loudspeaker chassis is proposed, said loudspeaker being able to be integrated into an acoustic box of an enclosure and also being able to comprise a mobile assembly comprising a membrane, the chassis comprising a front face arranged to be positioned at a first face of the acoustic box of the enclosure and in which an opening is formed defined by a periphery to which the membrane can be secured so that the membrane is in acoustic communication with the exterior of the acoustic box of the enclosure via the opening, the chassis further comprising a fixing lug which extends from the front face of the chassis towards the rear of the chassis, and which is arranged to be fixed to a second face of the acoustic box of the enclosure.

[0015] The mounting bracket allows the rigidity of the second face of the speaker cabinet to be transferred via the speaker chassis to the first face of the speaker cabinet. Since the second face deforms very little along the axis of movement of the speaker cone, the deformation of the first face during speaker operation is thus significantly limited.

[0016] Further provided is a chassis as previously described, wherein the front face of the chassis is arranged to be fixed to the first face of the acoustic enclosure of the speaker.

[0017] Further provided is a chassis as previously described, the chassis being arranged to be attached to the acoustic enclosure of the speaker only via one or more fixing lugs which extend from the front face of the chassis to the rear of the chassis and which are arranged to be attached to one or more second faces of the acoustic enclosure of the speaker.

[0018] Further provided is a frame as previously described, wherein the mounting tab has been formed by folding the front face over at least a portion of a length of an edge of the front face.

[0019] Further provided is a frame as previously described, wherein the front face is folded over the entire length of said edge so that the fixing tab extends over the entire length.

[0020] Further provided is a frame as previously described, in which an angle between a first plane in which the front face extends and a second plane in which the fixing lug extends is between 60° and 120°.

[0021] A frame as previously described is further provided, in which the fixing lug comprises a tapped hole for fixing it to the second face.

[0022] We also propose a loudspeaker comprising a chassis as previously described, and a moving assembly comprising a membrane secured to the periphery of the opening in the front face of the chassis.

[0023] We further propose an enclosure comprising a loudspeaker as previously described and an acoustic box in which the loudspeaker is integrated, the acoustic box of the enclosure comprising a first face and a second face, the membrane being in acoustic communication with the exterior of the acoustic box via the opening, the fixing lug being fixed to the second face of the acoustic box of the enclosure.

[0024] We also offer audio equipment incorporating a speaker as previously described.

[0025] Further provided is audio equipment as previously described, the audio equipment being a decoder box.

[0026] 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

[0027] Reference will be made to the attached drawings, including: [ Fig. 1 ] there figure 1 represents a side view, in perspective and in section along a plane parallel to a longitudinal axis of the loudspeaker, of a speaker of the prior art according to a first embodiment; [ Fig. 2 ] there figure 2 represents a side and perspective view of a prior art enclosure according to a second embodiment; [ Fig. 3 ] there figure 3 is a view similar to that of the figure 2 , but without the enclosure cover; [ Fig. 4 ] there figure 4 is a view similar to that of the figure 2 , which further illustrates the deformation of the enclosure box according to one of its natural deformation modes; [ Fig. 5 ] there figure 5 is a figure similar to the figure 3 , also illustrating the deformation of the enclosure box; [ Fig. 6 ] there figure 6 represents a perspective view of a loudspeaker chassis; [ Fig. 7 ] there figure 7 is a perspective and sectional view of part of the enclosure incorporating the loudspeaker chassis of the figure 6 ; [ Fig. 8 ] there figure 8 represents a section of a rectangular beam. DETAILED DESCRIPTION OF THE INVENTION

[0028] In reference to the figures 6 et 7 , the loudspeaker 20 is integrated into the acoustic box 19 of an acoustic enclosure 21. The enclosure 21 is intended to be integrated into audio equipment (not shown), which is for example a decoder box (or STB, for Set-Top Box ) improved, capable of reproducing audio signals.

[0029] The box 19 of the enclosure 21 comprises an upper face 22 and a cover 23 forming a rear face of the box 19 of the enclosure 21.

[0030] The loudspeaker 20 comprises a chassis 24. Such a chassis is also referred to as a “salad bowl”.

[0031] The chassis 24, with longitudinal axis X, comprises a front part 25, a central part 26 and a rear part 27.

[0032] The front part 25, of generally flat shape, defines the front face 28 of the chassis 24 which extends along a first plane P1 perpendicular to the axis X.

[0033] It is recalled that, according to a common meaning in the field considered, the expression “front face” designates the entirety of the plate 25 forming the front of the chassis 24.

[0034] The central part 26 is openwork and has a general truncated cone shape with axis X. The central part 26 connects the front part 25 and the rear part 27.

[0035] The rear part 27 is generally cylindrical in shape with axis X and circular in section. The external face of the bottom of the rear part 27 defines the rear face of the chassis 24.

[0036] The loudspeaker 20 also includes a core 30 and a magnet 31 positioned in the rear portion 27 of the chassis 24 of the loudspeaker 20.

[0037] The loudspeaker 20 further comprises a moving assembly positioned in the chassis 24. The moving assembly comprises a membrane 33 (shown in dotted lines, in section and in a very simplified manner) and a coil (not shown).

[0038] It is therefore understood that here, when we speak of the loudspeaker 20 and the chassis 24, by "front" we mean the side of the large diameter of the membrane 33 when the loudspeaker 20 is assembled, and by "rear" we mean the side of the magnet 31.

[0039] The front face 28 of the chassis 24 is here intended in particular to fix the loudspeaker 20 on a first face of the box 19 of the enclosure 21 in which the loudspeaker 20 is integrated. The first face is the upper face 22.

[0040] The front face 28 of the chassis 24, here made of sheet metal, is square in shape with rounded corners and comprises fixing means arranged to fix the front face 28 to the first face 22 of the box 19 of the enclosure 21. The fixing means here comprise four fixing holes 35, each positioned at a separate corner of the front face 28. The front face 28 also comprises a central opening 36 having the X axis as its central axis and defined by a circular periphery 37.

[0041] When the loudspeaker 20 is assembled, the membrane 33 of the loudspeaker 20 is secured, at its large diameter, to the periphery 37. More precisely, the membrane 33 is fixed to the periphery 37 by means of a peripheral suspension 38 which here has a toroidal shape. The periphery of the membrane 33, at its large diameter, therefore extends into the opening 36 along the periphery 37, and the membrane 33 is in acoustic communication with the outside of the box 19 of the enclosure 21 via the opening 36. When the loudspeaker 20 is operating, the membrane 33 undergoes a displacement of the X axis.

[0042] The chassis 24 further comprises at least one fixing lug 40, here only one in this case.

[0043] The fixing lug 40 extends from the front face 28 of the chassis 24 towards the rear of the chassis 24. More precisely, the fixing lug 40 extends from a central portion of an edge 41 of the front face 28 of the chassis 24.

[0044] The fixing lug 40 extends in a second plane P2.

[0045] The angle α between the first plane P1 and the second plane P2 is for example between 60° and 120°, and here is close to 90°.

[0046] The mounting bracket 40 is made of folded sheet metal. The mounting bracket 40 was formed by folding the front face 28 over a portion of a length of the edge 41 of the front face 28.

[0047] The fixing lug 40 comprises fixing means arranged to fix the fixing lug 40 to a second face of the box 19 of the enclosure 21. The second face is here the cover 23. The fixing means here comprise a tapped hole 42.

[0048] The second face 23 therefore meets the first face 22, that is to say that the box 19, inside which the acoustic volume of the enclosure 21 is defined, has an edge formed by an edge of the first face 22 and an edge of the second face 23.

[0049] A barrel 44 is formed in the cover 23, opposite which is the threaded hole 42 of the fixing lug 40 when the loudspeaker 20 is integrated into the housing 19 of the speaker 21. A screw extends through the barrel 44 and into the threaded hole 42 of the fixing lug 40 to fix the fixing lug 40 to the cover 23.

[0050] It is noted that here, the angle α between the first plane P1 in which the front face 28 of the chassis 24 extends, and between the second plane P2 in which the fixing lug 40 extends, is equal to 90°. However, as seen earlier, the angle α may be different from 90°. It is noted that the second plane P2, in which the fixing lug 40 extends, could also be oriented, relative to the first plane P1, by a certain angle around an axis perpendicular to the plane P1 (here axis X).

[0051] The angle β between the first plane P1, and the third plane P3 which is perpendicular to the second plane P2 and which passes through a central axis of the leg 40 (said central axis passing through the end of the leg 40 which is fixed to the edge 41, and being parallel to the axis X on the figure 6 ), can also be different from 90°.

[0052] The invention makes it possible to transfer the rigidity of the second face (cover 23) to the first face 22 of the box 19 of the speaker 21 by means of the fixing lug 40 and the chassis 24 of the loudspeaker 20.

[0053] The vibration antinode is therefore mechanically linked to a fixed point in the main direction of movement y from the first side 22.

[0054] We know that the quadratic moment is representative of the resistance of an object to twisting or bending.

[0055] For a beam of rectangular section of height h and thickness b, such as that shown in the figure 8 , the quadratic moments with respect to the axes x And y are given respectively by the following formulas: I x = bh 3 12 et I y = b 3 h 12 .

[0056] Thus, a beam with a large height h will have a quadratic moment I x large and will deform very little along the axis y . The second face 23 (cover) can be likened to a beam whose height h is large compared to the thickness of the first face 22. The quadratic moment I x of the second face 23 is substantial, so that, when the second face 23 is mechanically connected to the first face 22 by the addition of the fixing lug 40 on the chassis 24, it acts as a rib and completely stiffens the first face 22 on which the chassis 24 is fixed.

[0057] 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.

[0058] The mounting bracket is not necessarily made of folded sheet metal. It could, for example, be an added bracket, fixed by any means to the front of the chassis (by welding, for example).

[0059] The mounting bracket can extend along the entire length of one side of the front panel of the chassis. If the mounting bracket is formed by bending the front panel, the front panel is then bent along the entire length of the side and the mounting bracket extends along the entire length of the side. The mounting bracket then additionally acts as a rib.

[0060] The chassis may include several mounting tabs, which extend from one or more edges of the front face. Note, moreover, that the front face is not necessarily square or even rectangular, and that the mounting tab(s) may extend from any location on the front face (and not necessarily from an edge).

[0061] In the case where the chassis includes several fixing lugs, they can be intended either to fix the chassis to the same second face, or to several distinct second faces.

[0062] The speaker chassis can also be attached to the speaker cabinet only via one or more mounting brackets that are attached to one or more second faces of the speaker cabinet. In such a case, the front face of the chassis no longer has the mounting holes and the front face is no longer attached directly to the first face. This eliminates the need for mounting points in the same plane as the membrane in order to address design, assembly, or industrialization issues.

[0063] The first face, including the opening opposite which the membrane extends, and the second face, do not necessarily meet to form an edge and are not necessarily adjacent faces. The second face may be any face of the enclosure housing other than the first face.

[0064] It is noted that the invention is also applicable in the case where it is the chassis of the loudspeaker which presents a vibration mode to be eliminated.

[0065] The enclosure may comprise a sound box and an external covering distinct from each other or the sound box may have external faces arranged to constitute the external covering of the enclosure.

Claims

1. Chassis (24) of a loudspeaker (20), said loudspeaker (20) being able to be integrated into an acoustic box (19) of an enclosure (21) and also being able to comprise a mobile assembly comprising a membrane (33), the chassis (24) comprising a front face (28) arranged to be positioned at a first face (22) of the acoustic box of the enclosure and in which an opening (36) is formed, defined by a periphery (37) to which the membrane (33) can be secured so that the membrane (33) is in acoustic communication with the outside of the acoustic box of the enclosure via the opening, the chassis (24) further comprising a fixing lug (40) which extends from the front face of the chassis towards the rear of the chassis, and which is arranged to be fixed to a second face (23) of the acoustic box of the enclosure (21).

2. Chassis according to claim 1, in which the front face (28) of the chassis (24) is arranged to be fixed to the first face (22) of the acoustic box of the enclosure (21).

3. Chassis according to claim 1, the chassis (24) being arranged to be fixed to the acoustic box of the enclosure (21) only via one or more fixing lugs which extend from the front face of the chassis towards the rear of the chassis and which are arranged to be fixed to one or more second faces of the acoustic box of the enclosure.

4. Chassis according to one of the preceding claims, in which the fixing tab (40) has been formed by folding the front face (28) over at least a portion of a length of an edge (41) of the front face.

5. A frame according to claim 4, wherein the front face is folded over the entire length of said edge so that the fixing tab extends over the entire length of said edge.

6. Chassis according to one of the preceding claims, in which an angle (α) between a first plane (P1) in which the front face (28) extends and a second plane (P2) in which the fixing lug (40) extends is between 60° and 120°.

7. Chassis according to one of the preceding claims, in which the fixing lug (40) comprises a tapped hole (42) for its fixing to the second face.

8. Loudspeaker (20) comprising a chassis (24) according to one of the preceding claims, and a mobile assembly comprising a membrane (33) secured to the periphery (37) of the opening (36) of the front face (28) of the chassis (24).

9. Enclosure (21) comprising a loudspeaker (20) according to claim 8 and an acoustic box (19) in which the loudspeaker is integrated, the acoustic box of the enclosure comprising a first face (22) and a second face (23), the membrane (33) being in acoustic communication with the exterior of the acoustic box via the opening (36), the fixing lug (40) being fixed to the second face (23) of the acoustic box of the enclosure (21).

10. Audio equipment incorporating a speaker according to claim 9.

11. Audio equipment according to claim 10, the audio equipment being a set-top box.

Images