EP3448062B1

EP3448062B1 - Coaxial dual-voice-coil driver

Info

Publication number: EP3448062B1
Application number: EP18190735.3A
Authority: EP
Inventors: Shao Lin Yang; Yu Bing Zhan
Original assignee: Tymphany Hong Kong Ltd
Current assignee: Tymphany Hong Kong Ltd
Priority date: 2017-08-25
Filing date: 2018-08-24
Publication date: 2019-12-18
Anticipated expiration: 2038-08-24
Also published as: CN109429153A; CN109429153B; CN208724199U; EP3448062A1

Description

BACKGROUND

Technical Field

The present invention relates to a speaker, and in particular, to a coaxial dual-voice-coil driver in a speaker.

Related Art

When an electrical signal passes through a voice coil interacts and induces with a magnetic field of a permanent magnet to drive a diaphragm to vibrate air, a moving-coil speaker having the permanent magnet and the diaphragm implements electroacoustic conversion. In the prior art, the moving-coil speaker generally has a single diaphragm and a single voice coil, that is, in all audio sections, electroacoustic conversion is implemented through vibration of the single diaphragm.
However, the single diaphragm is not easy to balance a low frequency and a high frequency at the same time, and generally cannot satisfy a frequency range of 20 Hz to 20 kHz that is audible to human ears. Therefore, a design in which bass and treble are separate is used, and respective bands are separately replayed. A coaxial speaker means that a bass speaker and a treble speaker are placed at a same axis, and because the two speakers are located along the same axis and their physical positions are close to a point source, sound field positioning of replayed music is very ideal, and sound resolution is high.
In addition, generally, when treble and bass voice coils are disposed, the speaker drives the two voice coils respectively by using two magnetic circuit systems. Therefore, the volume is greater than that of one magnetic circuit of the single voice coil, and more magnets are required.

SUMMARY

To resolve the foregoing problem in the prior art, a coaxial dual-voice-coil driver is provided. The coaxial dual-voice-coil driver includes a yoke, a first magnet, a second magnet, a first concentrating flux plate, a second concentrating flux plate, a first voice coil, and a second voice coil. The yoke includes a base, a central cylinder, and a protruding portion. The central cylinder extends from the base along an axial direction, and the protruding portion extends from the central cylinder along the axial direction towards a direction away from the base. The first magnet includes a first axial hole. The central cylinder passes through the first axial hole, so that the first magnet is sleeved on the yoke and is in contact with the base. The second magnet is fixed on the yoke. The second magnet includes a second axial hole, and the protruding portion passes through the second axial hole, so that the second magnet is sleeved on the yoke and is in contact with a top surface of the central cylinder. A magnetic direction of the first magnet is the same as a magnetic direction of the second magnet. The first concentrating flux plate includes a first opening. At least a part of the protruding portion passes through the first opening, so that the second magnet is located between the first concentrating flux plate and the central cylinder. A first magnetic gap is provided between the first concentrating flux plate and the protruding portion. The second concentrating flux plate includes a second opening. The first opening and the second opening are coaxially disposed along a central axis, the second concentrating flux plate is disposed on the first magnet, and the first concentrating flux plate and the at least a part of the protruding portion are located in the second opening. A second magnetic gap is provided between the second concentrating flux plate and the first concentrating flux plate. The first voice coil is located in the first magnetic gap. The second voice coil is located in the second magnetic gap.
In an embodiment, a maximum magnetic energy product of the second magnet is greater than that of the first magnet. Preferably, the second magnet is a NdFeB ring-shaped magnet. Preferably, the first magnet is a ferrite ring-shaped magnet.
In an embodiment, the first voice coil is a treble voice coil, and the second voice coil is a bass voice coil.
In an embodiment, the first concentrating flux plate has a thickness gradually decreasing from an outer edge to the first opening. Preferably, a surface, in contact with the first magnet, of the first concentrating flux plate is planar.
In an embodiment, an outer radius of the second magnet is substantially the same as an outer radius of the first concentrating flux plate.
In an embodiment, an outer radius of the yoke is substantially the same as an outer radius of the second concentrating flux plate.
In an embodiment, the second concentrating flux plate has a thickness gradually decreasing from an inner edge to an outer edge. Preferably, a surface, in contact with the first magnet, of the second concentrating flux plate is planar.
In an embodiment, the base has a thickness gradually decreasing from the central cylinder to an outer edge. Preferably, a surface, in contact with the first magnet, of the base is planar.
In an embodiment, the central cylinder further includes a ring-shaped groove, and the groove is an annular groove disposed along an outer periphery of the protruding portion.
A person skilled in the art may understand that in the technical solutions of the present invention, the coaxial dual-voice-coil driver pushes two voice coils by using a same magnetic circuit system, to greatly reduce a quantity of magnets required in the voice coil driver, so that the volume can be reduced, a weight can be decreased, and a special structure design can also achieve an effect of loudspeaker. In addition, support elements can be reduced during assembly, steps required for assembly are reduced, and time required for assembly is shortened.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred implementations of the present invention are described below for a voice coil driver in a speaker with reference to accompanying drawings and use of a diaphragm, or double diaphragms, or a shape, a connection manner, a fastener position, and the like of a diaphragm are not limited.

FIG. 1 is a partially three-dimensional exploded view of a coaxial dual-voice-coil driver;
FIG. 2 is a partially cross-sectional view of a coaxial dual-voice-coil driver;
FIG. 3 is an enlarged diagram of an area B in FIG. 2; and
FIG. 4 is a diagram of distribution of magnetic lines of a coaxial dual-voice-coil driver.

DETAILED DESCRIPTION

Preferred implementations of the present invention are described below with reference to the accompanying drawings. A person skilled in the art should understand that these implementations are merely used to explain the technical principle of the present invention. A person skilled in the art may adjust the implementations when required, to make the implementations be applicable to specific application scenarios.
It should be noted that in the descriptions of this application, terms that indicate directions or position relationships such as "center", "above", "below", "left", "right", "vertical", "horizontal", "inside", and "outside" are based on directions or position relationships shown in the accompanying drawings, and are merely for ease of descriptions instead of indicating or implying that an apparatus or a component needs to have a particular orientation or be constructed or operated with a particular orientation. Therefore, the terms cannot be construed as limitations to this application. In addition, terms such as "first", "second", and "third" are merely for the purpose of description and cannot be construed as indicating or implying relative importance.
Besides, it should be noted that in the descriptions of this application, unless otherwise explicitly stipulated and limited, terms such as "mount", "link", and "connect" should be understood in broad sense, for example, may be a fixed connection, or a detachable connection, or an integrated connection; or may be a mechanical connection or an electrical connection; may be a direct connection or an indirect connection by using an intermediate medium; and may be communication within two components. A person skilled in the art may understand specific meanings of the terms in this application according to specific situations.
A coaxial dual-voice-coil driver of this application may apply to a speaker. Refer to FIG. 1 to FIG. 3. The coaxial dual-voice-coil driver 1 includes a yoke 70, a first magnet 10, a second magnet 20, a first concentrating flux plate 30, a second concentrating flux plate 40, a first voice coil 50, and a second voice coil 60. The yoke 70, the first magnet 10, the second magnet 20, the first concentrating flux plate 30, the second concentrating flux plate 40, the first voice coil 50, and the second voice coil 60 are coaxially disposed along a central axis A.
The first concentrating flux plate 30 and/or the second concentrating flux plate 40 may be made of a magnetic material, which has high magnetic saturation, large magnetic permeability, and low coercivity. Further, the concentrating flux plates may be made of soft magnetic material that has a narrow hysteresis curve and rapidly magnetization and demagnetization.
The magnetic reluctance of the magnetic material of each of the the concentrating flux plates 30, 40 is much smaller than the magnetic reluctance of the air. Normally, the magnetic permeability of the air is 1, and that of the soft magnetic material is 20,000. The concentrating flux plates 30, 40 using the magnetic material described above may have a uniform strong magnetic field in a necessary space, which is the path of the magnetic line and required for the magnetic circuit.
For example, the concentrating flux plates 30, 40 may be made from low-carbon steel such that the concentrating flux plates have a high saturation of magnetic induction intensity, a high permeability and a low coercivity. In particular, The high permeability means that the magnetic flux can more readily and easily pass through the concentrating flux plates 30, 40 than through air, and tends to condense the magnetic flux through these parts of the driver. Furthermore, the high saturation of magnetic induction intensity means that the concentration flux plates can be used to build a strong magnetic field in and around the voice coils to improve their movement during driving.
The yoke 70 is a T-shaped yoke and includes a base 72, a central cylinder 74, and a protruding portion 76. The central cylinder 74 extends upward from the base 72 along the axial direction A. The protruding portion 76 extends upward from the central cylinder 74 along the axial direction A. In FIG. 2, the central cylinder 74 of the yoke 70 has a thickness gradually decreasing from a center to two sides. In other words, a radius of the protruding portion 76 is smaller than a radius of the central cylinder 74.
The first magnet 10 includes a first axial hole 11, a first surface 102, and a second surface 104. The second magnet 20 includes a second axial hole 21, a first surface 202, and a second surface 204. The first surface 102 of the first magnet 10 is a contact surface of the first magnet 10 and the second magnetic conductive plate 40. The first surface 202 of the second magnet 20 is a contact surface of the second magnet 20 and the first magnetic conductive plate 30. Herein, magnetic poles of the first magnet 10 and the second magnet 20 are respectively located on the first surface 102/202 and the second surface 104/204. In an embodiment, a maximum magnetic energy product of the second magnet 20 is greater than that of the first magnet 10. Preferably, the second magnet 20 is a NdFeB ring-shaped magnet. Preferably, the first magnet 10 is a ferrite ring-shaped magnet.
The central cylinder 74 passes through the first axial hole 11 of the first magnet 10, so that the first magnet 10 is sleeved on the yoke 70. The second surface 104 of the first magnet 10 is in contact with the base 72. The second magnet 20 is located on the yoke 70, and the protruding portion 76 passes through the second axial hole 21 of the second magnet 20, so that the second magnet 20 is sleeved on the central cylinder 74 of the yoke 70, and the second surface 204 of the second magnet 20 is in contact with a top surface of the central cylinder 74.
The first concentrating flux plate 30 includes a first opening 31, and at least a part of the protruding portion 76 passes through the first opening 31, so that the second magnet 20 is sandwiched between the first concentrating flux plate 30 and the central cylinder 74. A contact surface between the central cylinder 74 and the first concentrating flux plate 30 is planar. Preferably, the first concentrating flux plate 30 has a thickness which changes, preferably decreases or is gradually decreasing from an outer edge to an inner edge. The first concentrating flux plate 30 includes a first step portion 302 and a second step portion 304. An outermost portion of the first concentrating flux plate 30 is the higher or thicker first step portion 302, and the second step portion 304 is inward adjacent to the first step portion 302. A notch 306 can be provided on the first step portion 302 for leads of voice coil passing through. For example, two notches 306 are disposed respectively at two corresponding end points on a diameter of the first concentrating flux plate 30.
Refer to FIG. 1 again. In an embodiment, a support member 80 may be disposed on the second step portion 304 of the first concentrating flux plate 30 for fixing the first concentrating flux plate 30, thereby avoiding excessively large vibration of the speaker. The support member 80 is not necessary, and therefore is represented by using dashed lines and is not shown in FIG. 2.
The second concentrating flux plate 40 includes a second opening 41, and the first opening 31 of the first concentrating flux plate 30 and the second opening 41 of the second concentrating flux plate 40 are coaxially disposed along the central axis A. The second concentrating flux plate 40 is disposed on the first magnet 10, and the first concentrating flux plate 30 and the at least a part of the protruding portion 76 are located in the second opening 41.
In an embodiment, an outer radius of the second magnet 20 is substantially the same as an outer radius of the first concentrating flux plate 30. An outer radius of the yoke 70 is substantially the same as an outer radius of the second concentrating flux plate 40.
Preferably, the base 72 may be cylindrical, circular-disk-shaped, hemispherical, or disk-shaped. The base 72 may have a thickness gradually decreasing from the central cylinder 74 to an outer edge. In other words, the base 72 is relatively thicker at its center and gradually becomes thinner towards its outer periphery. The contact surface between the first magnet 10 and the base 72 is planar, and the other surface of the base 72 becomes gradually inclined from a center to the outer periphery, so that the base 72 has a thickness gradually decreasing from the central cylinder 74 to the outer edge. The second concentrating flux plate 40 has a thickness gradually decreasing from an inner edge to an outer edge. Preferably, a contact surface between the second concentrating flux plate 40 and the first magnet 10 is planar, and the other surface of the second concentrating flux plate 40 inclines from a center to an outer periphery, so that the second concentrating flux plate 40 may have a thickness gradually decreasing from a center to the outer edge. In FIG. 2, the base 72 and the second concentrating flux plate 40 may present a vertically symmetrical change in thicknesses, so that the overall structure is dish-shaped, and the overall size is further reduced.
A first magnetic gap 500 is provided between the first concentrating flux plate 30 and the protruding portion 74, and the first voice coil 50 is located in the first magnetic gap 500. The first voice coil 50 is a treble voice coil. A second magnetic gap 600 is provided between the second concentrating flux plate 40 and the first concentrating flux plate 30. The second voice coil 60 is located in the second magnetic gap 600. The second voice coil 60 is a bass voice coil.
The thickness of the first magnet 10 is substantially the same as a height of the central cylinder 74, and an inner side wall of the second opening 41 corresponds to the first concentrating flux plate 30 when the second concentrating flux plate 40 is disposed on the first magnet 10. In an embodiment, an outer radius of the first magnet 10 is larger than an outer radius of the yoke 70, and a radius of the first axial hole 11 is larger than a radius of the central cylinder 74, so that the spacing between the central cylinder 74 and the first magnet 10 is larger than the first magnetic gap 500.
Refer to FIG. 1 again. A ring-shaped groove 78 is provided between the central cylinder 74 and the protruding portion 76, and the ring-shaped groove 78 is an annular groove disposed along an outer periphery of the protruding portion 76. The second magnet 20 may be very thin and adjustable for the first voice coil 50 as a voice coil stroke.
FIG. 4 is a diagram of distribution of magnetic lines of a coaxial dual-voice-coil driver. The direction of the magnetic field of the first magnet 10 is the same as that of the second magnet 20. That is, the second surface 104 of the first magnet 10 and the second surface 204 of the second magnet 20 have same magnetic poles. Therefore, the magnetic flux may be stopped from the second magnet 20 to the first magnet 10, and further to avoid magnetic field loss. It can be learned from FIG. 4 that, based on a principle of same poles repel, magnetic lines may be prevented from directly passing through the second magnet 20. Magnetic lines radiated out from the first magnet 10 make a detour when getting close to the second surface 204 of the second magnet 20. In other words, most magnetic lines flow to the first concentrating flux plate 30 and the second concentrating flux plate 40.
Preferably, the first surface 102 of the first magnet 10 and the first surface 202 of the second magnet 20 are both N poles. In other words, when in driving, the magnetic lines pass from an N pole to an S pole and pass from the first magnetic gap 500 to the second magnetic gap 600. That is, the first magnetic gap 500 and the second magnetic gap 600 may have relatively stronger magnetic fields. In such a magnetic circuit design, a relatively large amount of energy may be obtained and a relatively good sound making effect may be achieved.
Further, the second magnet 20 of this application is a NdFeB ring-shaped magnet using rare earth metals. A rare earth cobalt material not only has a large magnetic energy product but also has a large coercive force, and therefore can be made into a small and thin permanent magnet. Therefore, the structure provided in this application can effectively guide magnetic lines to pass from the first magnetic gap 500 to the second magnetic gap 600, so that the first magnetic gap 500 and the second magnetic gap 600 have relatively strong magnetic fields.

Claims

A driver (1), comprising:
a yoke (70) comprising a base (72), a central cylinder (74), and a protruding portion (76), wherein the central cylinder (74) extends from the base (72) along an axial direction (A), and the protruding portion (76) extends from the central cylinder (74) along the axial direction (A) towards a direction away from the base;

a first magnet (10) comprising a first axial hole (11), wherein the central cylinder (74) passes through the first axial hole (11), so that the first magnet (10) is sleeved on the yoke (70) and is in contact with the base (72);

a second magnet (20) located on the yoke (70), wherein the second magnet (20) comprises a second axial hole (21), and the protruding portion (76) passes through the second axial hole (21), so that the second magnet (20) is sleeved on the yoke (76) and is in contact with a top surface of the central cylinder, and the first magnet (10) and the second magnet (20) have the same direction of the magnetic field;

a first flux plate (30) comprising a first opening (31), wherein at least a part of the protruding portion (76) passes through the first opening (31), so that the second magnet (20) is located between the first concentrating flux plate (30) and the central cylinder (74), and a first magnetic gap (500) is provided between the first concentrating flux plate (30) and the protruding portion (76);

a second flux plate (40) comprising a second opening (41), wherein the first opening (31) and the second opening (41) are coaxially disposed along a central axis, the second concentrating flux plate (40) is disposed on the first magnet (10); wherein the first concentrating flux plate (30) and at least a part of the protruding portion (76) are located in the second opening (41), and a second magnetic gap (600) is provided between the second concentrating flux plate (40) and the first concentrating flux plate (30);

a first voice coil (50) located in the first magnetic gap (500); and

a second voice coil (60), located in the second magnetic gap (600).
The driver according to claim 1, wherein
a maximum magnetic energy product of the second magnet is greater than that of the first magnet.
The driver according to any one of the previous claims, wherein
the second magnet is a NdFeB ring-shaped magnet.
The driver according to any one of the previous claims, wherein
the first magnet is a ferrite ring-shaped magnet.
The driver according to any one of the previous claims, wherein
the first voice coil is a treble voice coil, and the second voice coil is a bass voice coil.
The driver according to any one of the previous claims, wherein
the first flux plate has a thickness gradually decreasing from an outer edge to an inner edge.
The driver according to any one of the previous claims, wherein
an outer radius of the second magnet is substantially the same as an outer radius of the first flux plate.
The driver according to any one of the previous claims, wherein
an outer radius of the yoke is substantially the same as an outer radius of the second flux plate.
The driver according to any one of the previous claims, wherein
the second flux plate has a thickness gradually decreasing from an inner edge to an outer edge.
The driver according to any one of the previous claims, wherein
the base has a thickness gradually decreasing from a center portion to an outer edge.
The driver according to any one of the previous claims, wherein
the central cylinder further comprises a ring-shaped groove, and the groove is an annular groove disposed along an outer periphery of the protruding portion.
The driver according to any one of the previous claims, wherein the driver is a coaxial dual-voice-coil.
The driver according to any one of the previous claims, wherein the first and second flux plates are each concentrating flux plates
The driver according to any one of the previous claims, wherein the first and second flux plates comprise a magnetic material, which has high magnetic saturation, large magnetic permeability, and low coercivity.
The driver according to any one of the previous claims, wherein the first and second flux plates are made of soft magnetic material that has a narrow hysteresis curve and has rapid magnetization and demagnetization, for example low-carbon steel.