JP2005503091A - Electroacoustic transducer with two diaphragms - Google Patents

Abstract

The present invention relates to electroacoustic transducers suitable for use in mobile communication devices and hearing aids. The transducer comprises two diaphragms positioned opposite to a magnetic circuit having two magnetic gaps. When used as a microphone, the transducer is substantially insensitive to vibration, and when used as a speaker, the transducer produces only very low vibration levels. Magnetic circuits have several advantages compared to conventional transducers having circular magnetic circuits. The transducer can be manufactured in lighter and very compact dimensions compared to conventional designs. In a more preferred embodiment, the diaphragm is rectangular. The transducer can be used as a vibration generator for silent alarm signals.

Description

【Technical field】
[0001]
The present invention relates to an electroacoustic transducer, and more particularly to an electrodynamic transducer having two diaphragms, each carrying a coil of conductive wire that is movable in a magnetic field.
[Background]
[0002]
Electroacoustic transducers, particularly electrodynamic transducers, are widely used in telecommunications devices such as wired, mobile or cellular telephones, and hearing aids where small size is a requirement. Both transducers and loudspeakers (speakers) used as microphones are used to convert acoustic signals into electrical signals and vice versa. In order to use both microphones and speakers in small devices, it is important to make the transducer resistant to vibrations to avoid unexpected noise or feedback problems.
[0003]
When the microphone and the speaker are arranged close to each other like a hearing aid, a feedback loop may be generated due to vibration generated by the speaker. The vibration from the speaker is transmitted to the microphone through the housing, and the microphone converts this vibration into an electric signal to some extent and amplifies it, and then converts it again into sound and vibration through the speaker. Thus, an unintended feedback loop is formed. Such a loop may cause sound quality degradation. In the case of a large gain, such as a hearing aid, the feedback loop can result in a disturbing howling noise, and is thus a limiting factor in the maximum gain possible in a hearing aid.
[0004]
In the prior art, rubber boot structures or box-in-box structures have been used to establish vibration isolation. In the box-in-box structure, the receiver was mounted in a gasket with very large compliance in order to obtain the necessary vibration isolation. When using a hearing aid that includes a telecoil, an extra housing is used as a magnetic shield.
[0005]
Another way to provide anti-vibration is to use two identical receivers (dual receivers) coupled from back to back, thereby reducing vibration from the entire system.
[0006]
The disadvantages of the rubber boot structure are that it does not provide sufficient vibration isolation and that design parameters are very difficult to design and control. The box-in-box structure is very large and tends to be bulky.
[0007]
The dual receiver structure does not completely cancel the vibration. This is because such a receiver always generates a rotational component when using a balanced armature type receiver as used in a hearing aid. Great vibration isolation can be achieved when using a dual receiver or speaker with two conventional radial electrodynamic transducers. Furthermore, such a transducer can be used in a mobile phone as a vibration generator that generates a silent alarm signal, saving the weight and space of a separately provided vibration generator.
[0008]
JP11308691A (English abstract) describes a speaker system comprising two diaphragms and one common magnetic circuit. When the two diaphragms move in opposite directions, the vibrational force applied to the magnetic circuit is minimized and the electroacoustic efficiency is increased compared to a single diaphragm speaker. However, the speaker system described in JP11308691A has disadvantages because the magnetic circuit and diaphragm are circular and the entire coil is positioned within the circular magnetic gap. Therefore, in order to reduce the distortion of such a speaker, the design is critically important, such as the centering of the voice coil, from the viewpoint of manufacturing variation. Furthermore, the magnetic circuit is bulky and is therefore not suitable for applications where the available space is very limited, especially with respect to the height of the speaker system. Furthermore, the JP11308691A speaker system requires a large number of individual parts and is therefore not suitable for low-cost mass production.
[0009]
JP07131893A (English abstract) describes two diaphragm loudspeakers having one common magnetic circuit. The speaker described in JP07131893A is intended to radiate sound having a high bi-directionality without phase shift. This is achieved by integrating two oscillating systems into one body. The diaphragm and magnetic circuit are circular, and the entire circular voice coil is positioned within the magnetic gap. The structure has several disadvantages. The structure is bulky because it relates to the technology of loudspeakers with high bi-directionality where parameters such as size and weight are not important. Therefore, the speaker of JP071131893A is not suitable for a small structure. Furthermore, the above-mentioned problems relating to distortion caused by the magnetic circuit not being perfectly symmetric are not solved. Furthermore, because of the large number of individual parts and complex shapes, the structure is not suitable for low-cost mass production.
[0010]
Thus, there is a need for an electroacoustic transducer in which the two diaphragms are substantially insensitive to vibration when used as a microphone and substantially free of vibration when used as a speaker. This transducer is suitable for small applications such as telecommunication devices and hearing aids.
DISCLOSURE OF THE INVENTION
[0011]
The object of the present invention is to provide an electroacoustic transducer of very compact dimensions for the general use of telecommunication devices and hearing aid devices.
[0012]
It is a further object of the present invention to provide an electroacoustic transducer having the following characteristics.
1. A dual speaker having a common magnetic circuit and two diaphragms;
2. Two possible modes of operation: vibration cancellation mode or vibration generation mode;
3. High efficiency due to optimized magnetic circuit with little leakage.
[0013]
According to the present invention, the above object is in the first aspect,
A magnetic circuit having first and second gaps, each having an upper and lower portion, further comprising magnetic means for forming a magnetic field within the first and second gaps;
First and second diaphragms opposed to the magnetic circuit;
A first coil of conductive wire secured to the first diaphragm, wherein the first coil is disposed in each of the upper portions of the first and second gaps. First and second gap portions of the wire, the first coil further comprising a wire bridge portion interconnecting the first and second gap portions of the wire, the first coil A first coil secured to the first diaphragm at least at the bridge portion of the wire;
A second coil of conductive wire fixed to the second diaphragm, wherein the second coil is disposed in each of the lower portions of the first and second gaps. First and second gap portions of the wire, wherein the second coil further comprises a wire bridge portion interconnecting the first and second gap portions of the wire, the second coil And an electroacoustic transducer comprising: a second coil secured to the second diaphragm at least at the bridge portion of the wire.
[0014]
The first coil may also be secured to the first diaphragm along at least a portion of one of its gap portions. Similarly, the second coil may be secured to the second diaphragm along at least a portion of one of its gap portions.
[0015]
Each of the first and second gaps may be defined by a pair of opposing surfaces that are substantially flat and substantially parallel to each other.
[0016]
The magnetic means may comprise first and second permanent magnets, the first magnet forming a magnetic field in the first gap, whereas the second magnet is A magnetic field is formed in the second gap. The magnetic circuit may include a body of soft magnetic material having first and second openings.
[0017]
Preferably, the first magnet is disposed in the first opening of the main body, whereas the second magnet is disposed in the second opening of the main body.
[0018]
The diaphragm can comprise a conductive portion, the conductive portion being connected to a wire end of the coil, the conductive portion being an externally accessible portion for electrically terminating the transducer It is.
[0019]
For hearing aid applications, a space overlap exists between the upper and lower portions of each of the first and second gaps. This space overlap is introduced to reduce the size of the transducer. For other applications, it is better to spatially separate the upper and lower portions of each of the first and second gaps.
[0020]
In a second aspect, the invention relates to a coil of conductive wire for use in the transducer according to the first aspect of the invention, said coil comprising:
A bridge portion defining a bridge surface having a substantially flat surface for securing to one of the diaphragms;
Each gap portion including a plurality of wire segments outside the bridge surface, the gap portion outside the bridge surface.
[0021]
Preferably, the wire segment in the gap portion is substantially straight.
[0022]
In a third aspect, the present invention is a method of manufacturing a coil from a conductive wire comprising:
Producing a coil defining a coil axis from a conductive wire;
Bending the coil about two bending axes substantially perpendicular to the coil axis.
[0023]
In a fourth aspect, the invention is a magnetic circuit for use in a transducer according to the first aspect, comprising:
A conductive magnetic material formed to define the pair of opposing surfaces defining a gap between a pair of opposing surfaces, the gap receiving portions of the first and second coils of the conductive wire. A magnetically conductive material that is adapted to
Magnetic means for establishing a magnetic field in the upper and lower portions of the gap, wherein the upper portion is adapted to receive a portion of the first coil and the lower portion is the second coil And a magnetic means adapted to receive the portion of the magnetic circuit.
[0024]
Preferably, each pair of opposed surfaces has a substantially flat surface that is substantially parallel to each other. The magnetic means may comprise a permanent magnet, and each of the permanent magnets has a substantially flat surface that constitutes one of the substantially flat surfaces of the gap. The magnetic circuit includes a body of soft magnetic material formed to define two openings in the body, each opening defining a pair of gaps defining the first and second gaps, respectively. Having opposite surfaces. Preferably, the magnetic means is disposed in an opening of the magnetic circuit.
[0025]
In a fifth aspect, the invention relates to a method of operating a transducer according to the first aspect, wherein the same electrical signal is simultaneously supplied to the first and second coils, the first and second diaphragms being Displace in the same direction.
[0026]
In a sixth aspect, the invention relates to a method of operating a transducer according to the first aspect, wherein the same electrical signal is simultaneously supplied to the first and second coils, the first and second diaphragms being Displace in the opposite direction.
BEST MODE FOR CARRYING OUT THE INVENTION
[0027]
Hereinafter, the present invention will be described in more detail with reference to the drawings.
[0028]
1 to 3 have main components: a magnetic circuit 10, a first coil 2, a second coil 12, a first diaphragm 1, a second diaphragm 13, and four terminals 6-9. 1 shows an electrodynamic transducer.
[0029]
As best shown in FIG. 1, an electrodynamic transducer according to the present invention comprises two diaphragms 1, 13 and two coils 2, 12 having a common magnetic circuit. The two diaphragms can be driven in two modes of operation, the same polarity or opposite polarities. When the two diaphragms are driven in the same direction in response to an input electrical signal, the transducer is driven in a so-called vibration mode. The vibration mode provides maximum vibration, but no sound is output. When the two diaphragms are driven in opposite directions, the maximum sound output is provided and there is no transducer vibration. Terminals 6 and 8 provide electrical contact with the coil 2, whereas terminals 7 and 9 provide electrical contact with the coil 12. Contact between the terminal and the coil can be made through the conductive portions 25, 26 of the diaphragm. The present invention is particularly suitable for applications where the available space of the speaker is very limited. By using the structure according to the present invention, very good efficiency to volume ratio and maximum power to volume ratio can be achieved.
[0030]
In the following, two embodiments are described, an embodiment suitable for telecommunications applications and an embodiment suitable for hearing aid applications. It should be understood that the present invention is not limited to applications within these fields.
[0031]
In FIG. 1, a pair of plastic housings 3, 11 are used to hold the magnetic system in place. The magnetic system comprises a magnetic circuit 10 having two long legs 27, 28 and two short legs 30, 30 'connected at their ends, forming a generally rectangular ring. The central leg 29 interconnects the two short legs 30, 30 'and divides the interior of the rectangular ring into two rectangular openings. The two long legs 27, 28, the two short legs 30, 30 'and the central leg 29 of the magnetic circuit are preferably made of a soft magnetic material having a high magnetic saturation value. The surfaces of the two long legs 27, 28 and the central leg 29 facing the opening 24 are substantially flat and define a gap between them.
[0032]
The central part of the long leg is removed and accommodates a part of the plastic housing 3, 11 with the holding rims 21, 22 for the magnets 4, 5 positioned in the opening 24. The aim is to obtain a simple assembly procedure based on a simple stacking operation. Each magnet has a magnetic pole facing the long leg portion and an opposite magnetic pole facing the central leg portion 29. Thus, depending on the positioning of the magnet, a magnetic gap is formed between the free pole surface and the central leg surface, or between the free pole surface and the long leg surface.
[0033]
Each magnet 4, 5 forms a magnetic field in the corresponding gap, and a magnetic return path is formed through the central leg 29, short legs 30, 30 and long legs 27, 28. Thus, the magnetic return path completely surrounds the magnet gap, and each of the magnets has a pole face that defines the gap. This provides a very flat and compact magnet system structure in which the magnetic field is concentrated in the gap, reducing stray fields, resulting in high sensitivity and reducing the need for magnetic shielding.
[0034]
The acoustic path is provided outside thereof, and for example, a volume portion in the mobile terminal can be used. This acoustic path must penetrate the plastic housing and the pole piece, thereby forming an acoustic tunnel that connects the outside world to the back volume of the speaker. Sound attenuation can be achieved by using a cloth, mesh, or generally sound attenuating material across the openings 15,18. The sound attenuating material may be inductive, resistive, or any combination thereof. The prepared acoustic tunnel can also be used for bass reflex to enhance the low frequency response as is known in other applications. The acoustic tunnel between the transducer back volume and the outside is partly removed in order to create an acoustic tunnel, as also shown in FIG. As shown, the acoustic tunnel is long and narrow around the edge of the magnetic circuit. With precise dimensions, such a narrow tunnel acts as an acoustic low-pass filter with a cut-off frequency in the range of less than 1 Hz. In FIG. 6, the two tunnels run half turn around the magnetic circuit, but the tunnel basically has multiple turns and occupies multiple layers of the stack forming the magnetic circuit.
[0035]
The volume of the back can be increased by removing a portion of the central leg 29 and, in this way, has almost no adverse effect on the magnetic circuit because its magnetic flux density is almost zero.
[0036]
The coils 2 and 12 are wound with a thin conductive wire such as copper, and include a plurality of windings electrically insulated from each other by, for example, a surface coating layer. The wire and coil are heated during winding, which makes the paint sticky and adheres the windings to each other, thereby mechanically stabilizing the coil. Each of the two coils, e.g., coil 2, has two wire ends for electrically connecting the coil to terminals 6 and 8 via a conductive path inside diaphragm 1.
[0037]
The coils 2, 12 are wound around a mandrel having a generally rectangular cross section, thereby giving the coil the shape shown in FIG. 4 having a generally rectangular opening 32 and a generally rectangular outer contour with rounded corners. . In FIG. 4, the coil is relatively flat and has a thickness that is less than the radial width of the coil between the inner and outer contours of the coil, typically 10-30% of the radial width. Or by subsequent operations performed on the coil.
[0038]
After winding the coil to the desired shape and thickness with the desired number of turns, the coil is removed from the mandrel. While the coil is still hot and the paint is still soft due to the high temperature, the coil is bent along two parallel bending axes 33 of a flat coil surface using a bending instrument (not shown). In this case, the shape shown in FIGS. 1 and 2 is given to the coil. The two long sections 34 of the coil are bent about 90 degrees with respect to the two short sections 35, and the two long sections 34 are parallel to each other. After bending, the coil is cooled, the paint is no longer soft and the coil is stable. Next, the bent and stabilized coil is fixed to the diaphragms 1 and 13. For telecommunications applications, the diaphragm is made, for example, from a thin and flexible sheet of flexible circuit board material. As seen in the lower part of FIG. 2, inside the diaphragms 1 and 13, there are conductive portions 25 and 26 made of, for example, copper. The two short sections 35 of the coil are fixed inside the diaphragm, for example by an adhesive, and the two wire ends 31 are electrically connected to each of the conductive portions 25, 26, for example by soldering or welding. This conductive part is used to strengthen and stabilize the central part of the diaphragms 1, 13 and to establish an electrical connection from the coil to the terminals 6-9 as already described. As a result, the use of thin wires from the moving coil to the fixed terminals 6 to 9 can be completely avoided, so that the reliability of the speaker is also improved. However, instead of this, the end of the wire may be electrically connected to the terminal of the casing, for example, by soldering.
[0039]
In an alternative embodiment, the coil may be formed by a flexible printed circuit board, ie a thin and flexible sheet such as a flexible print. Such a thin and flexible sheet is provided with a predetermined conductive path thereon so as to form a coiled electrical path. As will be explained later, the diaphragm also comprises a conductive portion in its preferred embodiment. Thus, the coil and diaphragm can be manufactured from a single sheet of flexible print with appropriate conductive paths, which is the remainder of the integrated diaphragm / coil structure where the two long sections of the coil are integrated. On the other hand, it is shaped to appear with an angle of 90 degrees. Diaphragms 1, 13 are rectangular and tongue 24 ′ extends from the longitudinal bending side of the diaphragm, and conductive portions 25, 26 extend to the tongue, resulting in the conductivity of the tongue. Portions 25 and 26 are electrically connected to respective ends of coil wire end 31.
[0040]
Next, diaphragms 1, 13 and coils 2, 12 secured thereto are mounted on a magnetic system with two long sections of coil 2 in the respective upper part of the gap. Similarly, the two long sections of the coil 12 are positioned in the respective lower part of the gap. Thus, the long section 34 is referred to as the coil gap. A short section 35 of the coil is arranged above the central leg 29 and bridges the gap portion of the coil.
[0041]
The section 35 is preferably used to secure the coil to the diaphragm, for example with an adhesive. Further, the coil may be secured to the diaphragm along at least a portion of one of the gap portions 34. The best mechanical connection between the coil and the diaphragm is achieved by securing the coil to the diaphragm along the entire length of both gap portions 34 using, for example, an adhesive. This increases the rigidity of the diaphragm, and therefore the diaphragm moves more like a piston.
[0042]
The diaphragm is secured to the magnetic system along its edge as shown in FIG. If desired, the short edge of the diaphragm can also be secured to the magnetic system or to the casing. Alternatively, the slot can be closed with a flexible material so that the short edge can move. However, the flexible material prevents air from moving from one side of the diaphragm to the other. If desired, the diaphragm edge can be secured to the magnet system with an adhesive.
[0043]
In the preferred embodiment, the diaphragm is rectangular, but other shapes can be used.
[0044]
Compliance around the diaphragm can be increased by providing holes with laser drilling. Furthermore, the general behavior of the two diaphragms can be averaged by providing holes in one or both diaphragms and adjusting the compliance between the two diaphragms.
[0045]
The magnetic circuit shown in FIG. 1 has a plurality of layers. The magnetic circuit can also be made as one solid block or as an outer ring with a central leg inserted.
[0046]
1 to 3 show that on the side of the magnetic circuit, the two-part plastic housings 3, 11 have a total of four grooves or channels extending in the longitudinal direction of the housing. These grooves are made to support the terminals 6-9, as can be seen from FIG. The channel has a height corresponding to the width of each of the terminals 6-9. Diaphragm 1 is connected to terminals 6 and 8, whereas diaphragm 13 is connected to terminals 7 and 9. The connection between the diaphragm and the terminal can be established by providing a thin layer of, for example, tin on that part of the diaphragm, and after assembly, contact between the transducer and the terminal is achieved. As can be seen from FIGS. 1-3, small holes are provided at each of these locations in the diaphragm. These holes are adapted to allow the laser beam to heat the diaphragm by heating the terminals, thereby allowing, for example, tin applied to these areas to melt. . Applying this procedure to all four areas to be connected to the terminals, the diaphragm is soldered to the terminals.
[0047]
In order to combine the outputs from the two diaphragms, a housing around the speaker is required. Such a housing is arranged such that the outlet from the back volume is separated from the output from the front of the diaphragm. Both the front and rear output ends of the different acoustic outlets are shown in FIG. As shown, ambient attachment can be established through compliant rubber materials 74, 75 such that a resonance of about 100-150 Hz is achieved. Maximum generated power is achieved when the transducer operates in a vibration mode that typically occurs in the frequency range of 100-150 Hz. The expected acceleration of about 1G can be achieved with a mass of 100 grams, for example representing the mass of one mobile phone. The various forms of rubber mounts may be springs, plastics, silicones, or any having appropriate compliance to obtain resonance in the desired frequency range, i.e., 100-150 Hz.
[0048]
This transducer is equally suitable as a speaker transducer and as a microphone. When used as a speaker transducer, an audio frequency electrical signal is supplied to the terminals, and the current generated in the gap portion of the coil wire interacts with the magnetic field in the gap to move the coil and diaphragm, producing an audio frequency sound. generate. Similarly, when used as a microphone, audible frequency sound acting on the diaphragm moves the diaphragm, and when the gap portion of the coil wire moves in the magnetic field, an electrical signal is generated and output to the transducer terminal.
[0049]
The transducer according to the invention can also be used as a ringer by tuning the transducer so that it has a resonant peak between about 1.5 kHz or 800 Hz to 3 kHz in use.
[0050]
Double diaphragm transducers can generally operate in two modes, and the two diaphragm coil systems are coupled electrically in phase (the diaphragm moves in the opposite direction) or in reverse phase (the diaphragm moves in the same direction) . When the transducer is coupled in-phase, it can be used as an efficient loudspeaker with a spherical directivity pattern. When coupled out of phase, the transducer is essentially a silent vibration source. When used as a microphone, the transducer has either a spherical pattern or a Lemnice skating (eighth-shaped) directional pattern.
[0051]
For example, for applications in mobile communication devices, double diaphragm transducers are very attractive because they can be used as a loudspeaker in normal operating mode as well as as a vibration source to provide a silent alarm signal. Thus, the double source transducer used for the two functions saves space and weight, and further reduces the total number of individual parts.
[0052]
For special applications, it may be of interest to have finer control over the directivity pattern of the double diaphragm transducer by using appropriate signal processing. However, the frequency range in which this can be done depends, inter alia, on the size of the diaphragm.
[0053]
For games on portable units, one mode can be considered, which is a mixture of vibration output and sound output, in order to stimulate the user not only with images and sounds, but also with mechanical means. The reason is that according to the present invention, it is possible to easily switch between the vibration mode and the sound mode by simply switching one polarity of the signal supplied to one of the coils.
[0054]
There is a major problem with feedback for hearing aids. Feedback means that vibration generated by a receiver (speaker) is mechanically coupled / transmitted to a hearing aid housing, and then converted back to sound, enters a microphone, and becomes feedback. Sometimes, direct coupling between a speaker and a microphone in a hearing aid is also a problem.
[0055]
The present invention can completely cancel the vibration because the movement of the diaphragm does not introduce a rotational component. This is determined in particular by the fact that the diaphragm is driven by a reasonably stiff coil and the drive points are spaced apart and everything else is very symmetric. The only difference is the diaphragm compliance difference.
[0056]
One possible way to optimize for this would be to utilize the back volume so that the diaphragm volume largely determines the compliance of the diaphragm. This is a great help because the back volume is the same for both diaphragms. In this case, one diaphragm should be acoustically sealed from the outside world. This is absolutely necessary for hearing aid applications where an excellent low frequency response is required. Pressure equalization holes must be provided in only one diaphragm.
[0057]
Another method is to use a stack for the magnetic circuit to construct an acoustic low pass filter. See FIG. 6 again. Normally, it is not permissible to have an opening in the back in a hearing aid because the sound radiated from such an opening is radiated inside the hearing aid resulting in feedback as previously described. is there. An acoustic low pass filter with a low cutoff frequency (eg, less than 1 Hz) can be formed so that the acoustic level with a high frequency is not so great as to cause feedback.
[0058]
A common acoustic chamber that combines the output from the diaphragm and the output of the tube is provided, and the output from the diaphragm and the output from the tube are the same in a certain frequency range at the point where the tube ends, as in the bass reflex loudspeaker. The phase can be as follows.
[0059]
The magnetic circuit of the transducer of the present invention is designed such that the AC flux of two coils driven with opposite polarities cancels. This dramatically reduces the need for shielding for magnetic feedback to the telecoil. As a result, plastic housings can be used for low gain hearing aids (cost savings), and shielding requirements are much lower for high gain hearing aids. The pole piece stack itself is a complete self-sealing magnetic circuit with excellent shielding properties.
[0060]
With regard to mechanical stability, the pole pieces, preferably formed as a laminated structure, are very stiff. The housing is directly coupled to the laminated structure and can be moved and displaced. This very rigid structure is a great advancement because such a rigid housing has less sound emission compared to today's hearing aid receivers with a housing with greater compliance.
[0061]
For hearing aid applications, having a thin transducer is very important. The method of thinning the structure of FIGS. 1-3 causes the coils 2, 12 to be located on top of each other so that they share the same gap as shown in the cross-sectional view of FIG. . Such a structure will cause some efficiency loss due to gap widening, but the thickness is significantly reduced. Similarly, different types of diaphragms with closed corners 81 are required for hearing aid applications. A transducer having such a diaphragm is shown in FIGS.
[0062]
Electronic means can be attached to at least one of the diaphragms, and such electronic means can be used for various purposes. The electronic means can be housed in one chip and mounted with an adhesive. If the impedance of the transducer coil is so low that it does not work with conventional electronic amplification devices used in mobile phones or the like, it is possible to include an impedance converter in the electronic means. For example, such a chip can be mounted on the coil side of the diaphragm. An impedance converter can increase the efficiency of the transducer, which can improve the filling of the magnetic gap by the conductive wire by reducing the number of single turns of the coil. Because there is. This is particularly important in embodiments where at least one of the diaphragms is a flexible print having an integral coil. In this solution, the conductive material has to be removed to form more turns, so this filling can be reduced considerably by increasing the number of turns. By using an impedance converter, it is possible to compensate for the impedance drop by reducing the number of turns, thus increasing the efficiency of the transducer.
[0063]
The electronic means may comprise means for detecting diaphragm movement, for example in combination with a feedback system. The electronic means may also comprise switching means such as means for switching between sound mode and vibration mode when the transducer is used as a loudspeaker. The electronic means can also comprise an attenuator for adjusting the volume.
[0064]
According to a preferred embodiment, the magnet circuit is rectangular and there are two gaps that receive the gap portion of the coil, these gaps being defined between opposing flat surfaces. In other configurations, the magnet circuit may have four gaps arranged like square sides, and then the coil will correspond to four gap parts arranged similarly like square sides. Would have. The bridge portion of the coil will then be at the corner of the square and will be secured to the four position diaphragm. The outer contour of the magnet circuit can have any desired shape, including a circular shape. Further, the gap and the gap portion of the coil can be bent like an arc.
[Brief description of the drawings]
[0065]
FIG. 1 is a perspective view of an embodiment of the present invention suitable for electronic communication applications, exploded from the top and viewed from above.
FIG. 2 is a diagram showing the same part as assembled (as in FIG. 1).
FIG. 3 is a view showing the same parts that are further assembled.
FIG. 4 shows a coil applied to a transducer according to the invention.
FIG. 5 is a cross-sectional view of another embodiment of the present invention suitable for a hearing aid.
FIG. 6 shows an acoustic tunnel for making an acoustic connection between the volume between the diaphragms and the outer region of the transducer.
FIG. 7 shows a fully assembled transducer suspended from two flexible members.
FIG. 8 shows a suitable transducer for use in a hearing aid.
FIG. 9 is a view showing the same part as assembled (as in FIG. 8).

Claims (26)

A magnetic circuit having first and second gaps, each having an upper and lower portion, further comprising magnetic means for forming a magnetic field within the first and second gaps;
First and second diaphragms opposed to the magnetic circuit;
A first coil of conductive wire secured to the first diaphragm, wherein the first coil is disposed in each of the upper portions of the first and second gaps. First and second gap portions of the wire, the first coil further comprising a wire bridge portion interconnecting the first and second gap portions of the wire, the first coil A first coil secured to the first diaphragm at least at the bridge portion of the wire;
A second coil of conductive wire fixed to the second diaphragm, wherein the second coil is disposed in each of the lower portions of the first and second gaps. First and second gap portions of the wire, wherein the second coil further comprises a wire bridge portion interconnecting the first and second gap portions of the wire, the second coil A second coil secured to the second diaphragm at least at the bridge portion of the wire;
An electroacoustic transducer. The transducer of claim 1, wherein the first coil is secured to the first diaphragm along at least a portion of one of its gap portions. The transducer of claim 1 or 2, wherein the second coil is secured to the second diaphragm along at least a portion of one of its gap portions. 4. The method according to claim 1, wherein each of the first and second gaps is defined by a pair of facing surfaces, and the pair of facing surfaces are substantially flat and substantially parallel to each other. The transducer as described in. The magnetic means comprises first and second permanent magnets, the first magnet forms a magnetic field in the first gap, and the second magnet generates a magnetic field in the second gap. The transducer according to claim 1, wherein the transducer is formed. The transducer of claim 5, wherein the magnetic circuit comprises a body of soft magnetic material having first and second openings. The transducer of claim 6, wherein the first magnet is disposed within a first opening of the body and the second magnet is disposed within a second opening of the body. The first gap is formed by the facing surface of the first magnet and the first long leg portion of the main body of soft magnetic material, and the second gap is facing the second magnet. 8. A transducer according to claim 7, formed by a surface and a second long leg of the body of soft magnetic material. The first gap is formed by an opposing surface of the first magnet and a central leg portion of the body of soft magnetic material, and the second gap is formed by an opposing surface of the second magnet and a soft surface. The transducer of claim 7 formed by a central leg of the body of magnetic material. The diaphragm comprises a conductive portion, the conductive portion is connected to a wire end of the coil, and the conductive portion is an externally accessible portion for electrically terminating the transducer. The transducer according to any one of 1 to 9. 11. Transducer according to any one of the preceding claims, wherein a spatial overlap exists between the upper and lower portions of each of the first and second gaps. 11. A transducer according to any one of the preceding claims, wherein the upper and lower portions of each of the first and second gaps are spatially separated. 13. A flexible circuit board, such as a flexible print, forms the first diaphragm, and the first coil is formed by a conductive path of the flexible circuit board. The transducer according to claim 1. A flexible circuit board, such as a flexible print, forms the second diaphragm, and the second coil is formed by a conductive path of the flexible circuit board. The transducer according to item 1. 15. A transducer as claimed in any preceding claim, further comprising electronic means mounted on at least one of the diaphragms. The transducer of claim 15, wherein the electronic means comprises an impedance converter. A bridge portion defining a bridge surface having a substantially flat surface for securing to one of the diaphragms;
A gap portion outside the bridge surface, each gap portion including a plurality of wire segments outside the bridge surface;
A coil of conductive wire for use in a transducer according to any one of the preceding claims. The coil of claim 17, wherein the wire segment in the gap portion is substantially straight. Producing a coil defining a coil axis from a conductive wire;
Bending the coil about two bending axes substantially perpendicular to the coil axis;
The coil manufacturing method which manufactures a coil from the electroconductive wire containing this. A magnetically conductive material formed to define the pair of opposing surfaces defining a gap between a pair of opposing surfaces, the gap receiving portions of the first and second coils of the conductive wire. A magnetically conductive material that is adapted to
Magnetic means for forming a magnetic field in the upper and lower portions of the gap, wherein the upper portion is adapted to receive a portion of the first coil and the lower portion is a portion of the second coil. Magnetic means adapted to receive;
A magnetic circuit for use in a transducer according to claim 1. 21. The magnetic circuit of claim 20, wherein each pair of opposed surfaces has substantially flat surfaces that are substantially parallel to each other. The magnetic circuit of claim 21, wherein the magnetic means comprises a permanent magnet, each permanent magnet having a substantially flat surface that constitutes one of the substantially flat surfaces of the gap. The magnetic circuit includes a body of soft magnetic material formed to define two openings in the body, each opening defining a pair of gaps defining the first and second gaps, respectively. The magnetic circuit according to any one of claims 20 to 22, which has a facing surface. 24. The magnetic circuit of claim 23, wherein the magnetic means is disposed within an opening of the magnetic circuit. 17. The transducer according to claim 1, wherein the same electric signal is simultaneously supplied to the first and second coils to displace the first and second diaphragms in the same direction. A transducer operating method. 17. The transducer according to claim 1, wherein the same electrical signal is simultaneously supplied to the first and second coils, and the first and second diaphragms are displaced in opposite directions. A transducer operating method.