Motor for speaker with two opposing magnets

Abstract

The loudspeaker (1) includes a magnetic circuit (4). The loudspeaker (1) includes a moving assembly (5) movable relative to the magnetic circuit (4). The voice coil carrier (30) is movable through air gaps (77, 86), and a guiding element (105) for the moving assembly (5) is disposed between the moving assembly (5) and a chassis (3), on the side of a diaphragm (35) relative to the magnetic circuit (4). The moving assembly (5) passes completely through the magnetic circuit (4) via end air gaps (86, 87). The loudspeaker (1) includes a supplementary guiding element (110), disposed between the moving assembly (5) and the chassis (3), on the side opposite the diaphragm (35) relative to the magnetic circuit (4).

Description

[0001] The present invention relates to a loudspeaker comprising a chassis comprising a magnetic circuit comprising on the one hand a toroidal external metal carcass around an axis and on the other hand a stack comprising a central metal core placed between a first magnet and a second magnet, of polarities of opposite directions along the axis, aligned along this same axis and themselves placed between a first metal disc, and a second metal disc, the central core and at least one disc delimiting with the carcass an air gap, the loudspeaker comprising a movable assembly movable relative to the magnetic circuit along the axis, the movable assembly comprising a coil holder carrying a coil and a membrane, the coil holder being mounted movable through the air gaps, the loudspeaker comprising a first element for guiding the movable assembly arranged between the movable assembly and the chassis on the membrane side relative to the magnetic circuit.

[0002] Document US 7065 225 B2 describes a loudspeaker comprising a magnetic circuit comprising two magnets of coaxial polarities and opposite directions and a central core placed between the two magnets, which are themselves placed between, on the one hand, a metal disc, and on the other hand, a yoke formed of an outer shell in the form of a ferrule closed at one end by a metal disc. The yoke surrounds the magnets, the central core and the metal disc, thus closing the magnetic circuit.

[0003] WO 99 / 31931 A1 discloses a loudspeaker motor having two opposing magnets.

[0004] A coil is secured to a coil holder which is connected to the membrane, thus forming a moving element movable through the magnetic circuit. The coil surrounds the central core and is itself surrounded by the yoke, so that the coil crosses the magnetic circuit in an annular air gap. A first guide element for the moving element, commonly called a suspension, connects the membrane to a flared casing commonly called a salad bowl. A second guide element, of the corrugated joint type commonly called a "spider", connects the coil holder to the same flared casing. The first and second guide elements are placed on the same side of the magnetic circuit.

[0005] The problem with maintaining the spool holder in this way is insufficient translational guidance of the spool holder.

[0006] The aim of this invention is to provide a loudspeaker which allows improved guidance of the reel holder.

[0007] To this end, the invention relates to a loudspeaker as presented in claim 1.

[0008] The loudspeaker according to the invention has a large axial spacing between the guide elements which are arranged on either side of the magnetic circuit, improving the translational guidance of the moving assembly.

[0009] According to further advantageous aspects of the invention, the loudspeaker is in accordance with claims 2 to 7.

[0010] The invention further relates to an audio apparatus according to claim 8.

[0011] The invention will be better understood on reading the description which follows, given solely as a non-limiting example and made with reference to the appended drawings in which: [ Fig 1 ] there figure 1 is a partial sectional view of a loudspeaker, according to a first embodiment which is not, however, part of the invention; [ Fig 2 ] there figure 2 is a partial sectional view of a loudspeaker, according to a second embodiment which is not, however, part of the invention; [ Fig 3 ] there figure 3 is a partial sectional view similar to that of the figure 2 , of a loudspeaker according to a third embodiment. This embodiment is part of the invention; and [ Fig 4 ] there figure 4 is a partial sectional view different from that of the figures 2 And 3 , of a loudspeaker according to an alternative embodiment.

[0012] The loudspeaker 1 comprises a chassis 3 comprising a magnetic circuit 4, and a mobile assembly 5 which can slide relative to the chassis 3 along an axis AA.

[0013] The moving assembly 5 comprises a coil 25 secured to a revolution coil holder 30. The coil holder 30 is oriented along an axis AA.

[0014] In the embodiment of the figure 1 , the coil 25 comprises only a central winding section 31. The central winding section 31 is formed by a winding of at least one conductive wire, wound around the coil holder 30 and distributed over one or more layers.

[0015] The spool holder 30 comprises a tubular main body 32, one end of which is fixed to a membrane 35. The membrane 35 is for example formed from injected plastic. The membrane 35 comprises a groove 40. The tubular main body 32 of the spool holder is embedded in the groove 40 of the membrane. The spool holder 30 is for example glued to the membrane 35 in the groove 40.

[0016] In the embodiment illustrated in figure 1 , the mobile assembly 5 comprises a divergent 45 extending the tubular main body 32 of the reel holder at its other end. The divergent has a shape of revolution of axis AA. The divergent 45 is for example formed from injected plastic. It comprises a groove 50, and the tubular main body 32 of the reel holder is embedded in the groove 50. The reel holder body 30 is for example glued to the divergent 45 in the divergent groove 50. The free end of the divergent 45 opposite its connecting end of the main body 32 is wider than the end of the main body 32.

[0017] The magnetic circuit 4 comprises a cylindrical metal frame with axis AA denoted 52 composed of a first metal ferrule 55 on the side of the membrane 35 and a second metal ferrule 60 on the side opposite the membrane 35. The two ferrules 55, 60 are connected along a peripheral shoulder.

[0018] In the embodiment illustrated in figure 1 , , the two ferrules 55, 60 have, at their ends opposite their shoulders, an internal collar 61, 62 reducing their internal diameter. An internal counterbore is thus provided for housing the central winding section 31. The internal diameter of the carcass 52 is thus smaller at its two ends than in its central region.

[0019] The magnetic circuit also comprises a stack 63, of axis AA placed inside the volume formed by the carcass 52.

[0020] The stack 63 comprises two magnets 65, 70, both disc-shaped. A light passes through the two magnets 65, 70, for example along the axis AA. The disc shape of the two magnets is then more particularly, according to this embodiment, a ring shape. In a variant not shown, the disc shape of the two magnets 65, 70 is a solid shape. The disc shape of the two magnets 65, 70 is then more particularly, according to this embodiment, a plate shape.

[0021] The axis and field of the magnets are aligned along the AA axis. Magnets 65 and 70 are, for example, ferrite magnets.

[0022] The stack 63 also comprises a central metal core of revolution with axis AA denoted 75 placed between the magnets 65 and 70, in contact with them. The central core 75 laterally forms a pole of the magnetic circuit opposite the ferrule 55 and delimits an air gap 77 with this ferrule 55 in which the central winding section 31 extends. At rest, the central winding section 31 alone forming the coil 25 extends opposite the central core 75.

[0023] The stack 63 comprises two metal discs 80, 85 with axes of revolution AA. A light passes through the two discs 80, 85, for example along the axis AA. The two metal discs 80, 85 are then comparable to rings. In a variant not shown, the two metal discs 80, 85 are solid. The two metal discs 80, 85 are then comparable to trays.

[0024] The first metal disc 80 is placed between the magnet 65 and the membrane 35, in contact with the magnet 65. The magnet 70 is located between the second metal disc 85 and the central core 75, in contact with them. The metal discs 80, 85 define, with the carcass 52, two air gaps 86, 87, hereinafter called end air gaps, of the magnetic circuit.

[0025] The metal discs 80, 85 are surrounded by the collars 61, 62 of the carcass with which they form the two end air gaps 86, 87 of the magnetic circuit.

[0026] The frame 3 comprises a central pillar 90 in contact with the second metal disc 85, on the side opposite the second magnet 70. The central pillar 90 is for example a stamped steel part. The central pillar 90 has a vase shape, the end in contact with the second metal disc 85 forming a widening collar with an external diameter substantially similar to that of the second magnet. The central pillar 90 comprises a shoulder 91 narrowing its diameter at its opposite end.

[0027] The chassis 3 also includes a flared casing 93, commonly called a salad bowl, extending the first shell 55 on the side of the membrane 35. The flared casing 93 widens in a direction opposite to the first shell 55 and receives the membrane 35 at its larger diameter open end.

[0028] The loudspeaker according to the invention comprises a guide element for the moving assembly on the side of the membrane 35, consisting of a suspension 105 in the form of an O-ring. The suspension 105 is connected on the one hand to the large diameter end of the flared casing 93 and on the other hand to the periphery of the membrane 35, the membrane being surrounded by the suspension. The suspension in section has an Ω shape.

[0029] The suspension 105 is for example glued on the one hand to the flared casing 93 and on the other hand to the membrane 35.

[0030] A complementary guide element 110 is arranged on the opposite side to the membrane 35 with respect to the magnetic circuit 4. It is formed of a corrugated seal. This type of seal is also called a "spider" in English. In embodiments not illustrated, the complementary guide element 110 is formed by a suspension in the form of an O-ring, for example having a cross-section in the shape of an Ω. The general shape of the complementary guide element 110 is then similar to the general shape of the suspension 105.

[0031] The complementary guide element 110 is in contact on the one hand with the central pillar 90 and on the other hand with the divergent 45. The complementary guide element is in contact with the wide end of the divergent 45 and in contact with the shoulder 91 of the central pillar. The complementary guide element 110 is for example glued with the divergent 45 and with the central pillar 90.

[0032] The chassis 3 comprises a cover 115 for protecting the complementary guide element 110, connecting the free base of the pillar 90 to the carcass 52 by surrounding the complementary guide element 110. Its diameter and its length allow the movement of the complementary guide element 110 and of the mobile assembly 5 during operation of the loudspeaker 1.

[0033] Electrical supply wires 117, 118 are connected on either side of the coil 25. The protective cover 115 on the one hand and the flared casing 93 on the other hand each have a passage hole 120, 125 for the supply wires 117, 118, opening on either side of the coil holder. The coil 25 thus consists of an odd number of layers of wires.

[0034] A feed from either side of the coil 25 makes it possible to obtain a coil comprising an odd number of layers of wires. Alternatively, for an even number of layers of wires in the coil 25, the feed wires emerge from the same side of the coil. The protective cover 115 then comprises the two passage holes for the feed wires 117, 118.

[0035] The magnetic field generated by the opposing magnets 65 and 70 is conducted by the magnetic circuit 4. The magnetic flux is of opposite direction in the central air gap 77 and in the air gaps 86 and 87. Thus, the electromagnetic force on the moving assembly 5 generated by a current flowing in the central winding section 31 is of opposite direction in the air gaps 86 and 87 compared to the force generated by this same current in the central air gap 77. The further the central winding section 31 moves away from the central air gap 77, the more the amplitude of the electromagnetic force generated by the magnetic flux of the central air gap 77 decreases and the more the amplitude of the electromagnetic force generated by the flux of one of the air gaps 86 and 87 increases. This forms a magnetic braking of the moving assembly 5.

[0036] The suspension 105 and the complementary guide element 110 are both fixed on the one hand to the chassis 3 and on the other hand to an element of the moving assembly 5. The guide elements hold the moving assembly 5 at its two ends, on either side of the magnetic circuit 4. This position of the guide elements on the moving assembly 5 makes it possible to guide the movement of the moving assembly 5 in order to allow movement mainly in translation parallel to the axis AA and to prevent any rotation of the moving assembly 5 relative to the rest of the loudspeaker 1.

[0037] On the figure 2 a detail of a second embodiment of the loudspeaker 1 is shown. This embodiment differs from the first embodiment only in the following. Similar elements bear the same references.

[0038] In this embodiment, the coil 25 comprises, in addition to the central winding section 31, two end winding sections 130, 135.

[0039] Like the central winding section 31, the end winding sections 130, 135 are formed by a winding of at least one conductive wire, wound around the coil holder 30 and distributed over one or more layers. The central winding section 31 and the end winding sections 130, 135 are for example formed by the same conductive wire, the sections being for example connected by unwound sections of the conductive wire.

[0040] The end winding sections 130, 135 each extend at rest through an end air gap 86, 87.

[0041] When the central winding section 31 is aligned with the central air gap 77, the end winding sections 130, 135 are each aligned with a respective end air gap 86, 87.

[0042] The winding direction of the end winding sections 130, 135 around the coil holder 35 is opposite to the winding direction of the central winding section 31 around the coil holder 35. In other words, when the central winding section 31 is wound in a clockwise direction, seen from the side of the membrane 35, the end winding sections 130, 135 are wound in a counterclockwise direction, seen from the side of the membrane 35, and vice versa. Such a winding is particularly advantageous since it makes it possible to exploit the magnetic field circulating in the end air gaps 86, 87 and the carcass 52 by using a single signal in the coil 25. On the figure 2 , the ferrules 55, 60 are devoid of internal collars 61, 62 and the two magnets 65, 70 are radially set back relative to the central core 75 and relative to the first 80 and second 85 metal discs. The second embodiment is however compatible with the ferrules 55, 60, with the magnets 65, 70 with the central core 75 and with the first 80 and second 85 metal discs of the first embodiment previously presented.

[0043] On the figure 3 a detail of a third embodiment of the loudspeaker 1 is shown. This embodiment differs from the second embodiment only in the following. Similar elements bear the same references.

[0044] According to this embodiment, end winding sections 130, 135 are at rest offset outwards, in a direction parallel to the axis AA, from the end air gaps 86, 87.

[0045] As visible on the figure 3 , the end winding sections 130, 135 are for example both offset away from the central core 75 relative to the air gaps 86, 87. In other words, when the central winding section 31 is aligned with the central air gap 77, the end winding sections 130, 135 are offset from the end air gaps 86, 87 away from the central core 75. By offset is meant here that median planes of the end winding sections 130, 135 are offset relative to the median planes of the air gaps 86, 87, the end winding sections 130, 135 extend for example however at least partially in the air gaps 86, 87. Such an offset is particularly advantageous since it makes it possible to ensure linearity of the electromagnetic force applied by the coil 25 to the coil holder 30, the sum of the surfaces of the coil sections in the air gaps 77, 86 and 87 being substantially constant, whatever the position of the moving assembly 5.

[0046] In the second and third embodiments, the extent along the axis AA of the end winding sections 130, 135 is for example different from the extent of the central winding section 31, and for example greater than the extent of the central winding section 31 (not shown in the figures 2 And 3 ).

[0047] In the second and third embodiments, the number of layers of wound wire forming the first 130 and second 135 end winding sections is for example different from the number of layers forming the central winding section 31, and for example less than the number of layers forming the central winding section 31 (not shown in the figures 2 And 3 ).

[0048] On the figure 4 A detail of a variant of the loudspeaker 1 is shown, compatible with any of the first, second and third embodiments previously described. This variant differs from the variants of the first, second and third embodiments only in the following. Similar elements bear the same references.

[0049] The moving assembly 5 comprises a connection section 140 in place of the divergent 45. The connection section 140, like the divergent, extends the tubular main body 32 of the reel holder, has a shape of revolution of axis AA and is for example formed from injected plastic. It comprises a groove and the tubular main body 32 of the reel holder is embedded in the connection section 140.

[0050] In the example of the figure 4 , the connection section is tubular.

[0051] Depending on the variant of the figure 4 , the complementary guide element 110 is in contact on the one hand with the protective cap 115 and on the other hand with the connection section 140. Unlike the variant of the embodiment presented in figure 1 , where the complementary guide element 110 extends radially towards the inside of the mobile assembly 5, the guide element 110 extends, in the variant presented in figure 4 , radially outwards from the moving assembly 5.

Claims

1. A speaker (1) comprising a frame (3) comprising a magnetic circuit (4) having on the one hand an external metal casing (52) that is toroidal about an axis (A-A) and on the other hand a stack (63) comprising a metallic central core (75) placed between a first magnet (65) and a second magnet (70), with polarities of opposite directions along the axis (A-A), aligned along this same axis and themselves placed between a first metal disc (80) and a second metal disc (85), the central core (75) and at least one disc (80) delimiting an air gap (77, 86) with the casing, the speaker (1) comprising mobile equipment (5) that is movable relative to the magnetic circuit (4) along the axis (A-A), the mobile equipment (5) including a spool holder (30) bearing a spool (25) and a membrane (35), the spool holder (30) being mounted movably through the air gaps (77, 86), the speaker (1) including a first guide element (105) of the mobile equipment (5) arranged between the mobile equipment (5) and the frame (3) on the side of the membrane relative to the magnetic circuit (4); wherein each metal disc (80, 85) delimits, with the casing (52), an end air gap (86, 87), the mobile equipment (5) passes all the way through the magnetic circuit (4) through the end air gaps (86, 87) and the speaker (1) includes an additional guide element (110), arranged between the mobile equipment (5) and the frame (3), on the side opposite the membrane (35) relative to the magnetic circuit (4); wherein the spool (25) comprises a central winding section (31) and two end winding sections (130, 135), the end winding sections (130, 135) extending at rest each at least partially through an end air gap (86, 87); characterized in that, when the central winding section (31) is aligned with the central air gap (77), the end winding sections (130, 135) are offset from the end air gaps (86, 87) at a distance from the central core (75).

2. The speaker (1) according to claim 1, including a protective cap (115) secured to the metal casing (52) and which surrounds the complementary guide element (110).

3. The speaker (1) according to claim 1 or 2, including a central pillar (90) extending the stack (63) on the side opposite the membrane (35), the complementary guide element (110) being connected to the central pillar (90).

4. The speaker (1) according to any one of the preceding claims, wherein the mobile equipment (5) includes, at its end opposite the membrane (35), a divergent (45), the section of which increases at its end opposite the membrane (35), the complementary guide element (110) being connected to the end of large diameter of the divergent (45).

5. The speaker (1) according to any one of the preceding claims, wherein the metal casing (52) includes a first shell (55) and a second shell (60), which are coaxial, arranged end to end in the extension of one another.

6. The speaker (1) according to any one of the preceding claims, wherein the spool (25) is extended by lead wires (117, 118) circulating through air gaps (86, 87) delimited by the two metal discs (80, 85).

7. The speaker (1) according to any one of the preceding claims, wherein the inner diameter of the casing (52) along any plane perpendicular to the axis (A-A) is smaller at its two ends than in its central region.

8. An audio device, comprising a speaker (1) according to any one of the preceding claims.

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