JPH01286699A - Speaker - Google Patents

Abstract

PURPOSE:To flatten a frequency characteristic and to make sensitivity satisfactory by forming a diaphragm and a conducting part with a high polymer material having conductivity. CONSTITUTION:When an a.c. current as a sound signal is applied to a primary feeding coil 3, a.c. magnetic flux corresponding to an input waveform is generated. Since a ring conducting part 8 has satisfactory conductivity and is closely interlinked with the a.c. magnetic flux, an induced current having the same frequency as that of the a.c. current is induced in the conducting part 8 by a mutual inducing phenomenon. Since the conducting part 8 is positioned in a magnetic cavity 10, force proportional to the product of the intensity of a d.c. magnetic field in the magnetic cavity part 10 and the induced current is acted on the conducting part 8. Namely, the induced current of the conducting part 8 interacts with the d.c. magnetic field in the magnetic cavity part 10, drives a diaphragm 2, and radiates a sound wave. Since the diaphragm 2 composed of a high polymer film having the conductivity has a comparatively large mechanical loss and light weight, in never generates a resonance peak in the frequency characteristic, and the frequency characteristic of a speaker 1 can be flattened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to loudspeakers, particularly inductive loudspeakers.

[Summary of the invention]

A speaker according to the present invention includes a diaphragm having an annular conductive part, a power supply coil disposed to face the conductive part with a predetermined gap, and a magnetic circuit to which the power supply coil is attached. The present invention is characterized in that the plate and the conductive portion are made of a conductive polymer material.

Therefore, the resonance peak in the frequency characteristics can be eliminated,
The frequency characteristics of the speaker can be made flatter. At the same time, the sensitivity of the speaker can be improved.

[Conventional technology]

In conventional electrodynamic speakers, driving force is obtained by passing an audio signal current through a voice coil in a DC magnetic field.

This audio signal current is normally supplied to the voice coil from the outside through a lead wire fixed to a paper cone serving as a diaphragm.

[Problem to be solved by the invention]

However, since conventional electrodynamic speakers are equipped with lead wires, they have the disadvantage that the lead wires are easily cut due to the reciprocating movement of the diaphragm. On the other hand, even if the lead wire is not cut, the linearity of the reciprocating motion of the diaphragm is inhibited, which tends to cause sound distortion, and the lead wire itself resonates, producing abnormal noise. there were. Furthermore,
During manufacture, the lead wire had to be drawn out through a narrow gap in the speaker, positioned, and then glued and fixed, making assembly difficult.

Therefore, in order to solve the above-mentioned various drawbacks, an induction type speaker without lead wires was developed in the Tokugawa Publication No. 56-2.
It is disclosed in Publication No. 7039. In the speaker disclosed in the above publication, the lead wire is removed and a drive coil is placed near the voice coil wound around the voice coil bobbin. An audio signal current is supplied to this drive coil, and the audio signal current is supplied from this drive coil to the voice coil by magnetic induction.

In other words, when an AC signal from an audio frequency power amplifier flows through the drive coil, the AC signal causes the drive coil to generate an AC magnetic flux corresponding to the human power waveform, and this AC magnetic flux is closely connected to the voice coil located at a close distance. interlink. On the other hand, since the voice coil itself is short-circuited, a short-circuit current flows through the voice coil due to the above-mentioned alternating current magnetic flux. Since the voice coil is located within the magnetic field created by the pole piece and the surrounding magnetic poles, a force proportional to the product of the strength of the magnetic field and the short-circuit current acts on the voice coil. This force causes the cone to vibrate from the voice coil through the voice coil bobbin, and sound is radiated from the cone like a normal speaker.

In the technology disclosed in the above-mentioned publication, the lead wires are removed, so although various drawbacks caused by the lead wires are resolved, the following problems also occur. .

Since the voice coil is generally fixed to the voice coil bobbin with an adhesive, there is a drawback that the driving force generated in the voice coil is difficult to be directly transmitted to the cone.

Furthermore, the voice coil inevitably generates heat due to short-circuit current, but there is a drawback in that it is difficult to properly dissipate this heat.

As a general trend, in order to improve speaker sensitivity, it is required to narrow the gap (magnetic gap) between the coil bobbin and the drive coil, and to wind the voice coil multiple times within this gap. ing. Therefore, the diameter of the metal wire used in the voice coil inevitably becomes smaller.
The heat capacity of the metal wire becomes smaller. As a result, in addition to the problem of heat dissipation as described above, the voice coil becomes susceptible to disconnection due to heat generation, which results in a drawback that the current capacity is limited.

Furthermore, there is a drawback that the paper voice coil bobbin is carbonized due to the above-mentioned heat generation being repeated.

Therefore, an induction type speaker without a voice coil has been proposed in Japanese Utility Model Application Publication No. 105438/1983.

That is, in a magnetic gap in a magnetic circuit, a diaphragm having an annular conductive part is supported by a damper so as to be able to freely vibrate, and a feeding coil is arranged to face the conductive part and electrically coupled to the conductive part by mutual induction. It is to be established.

This speaker eliminates the voice coil by generating an induced current based on mutual induction in an annular conductive portion formed in a portion of the diaphragm.

In the technique disclosed in the above-mentioned publication, not only the lead wire but also the voice coil is removed, so various drawbacks caused by the lead wire, voice coil, etc. are eliminated.

However, the above-mentioned diaphragm must be made of metal because it is necessary to generate an induced current in a conductive portion that is a part of the diaphragm.

If the diaphragm is made of metal, there is little mechanical loss and it is relatively heavy, so the frequency characteristics of the speaker will not be flat, resulting in sharp peaks of resonance, as shown in Figure 2. There is a problem in that it becomes difficult to damp the diaphragm when it resonates.

As a result, there was a problem in that the sound quality was impaired during resonance.

Furthermore, if the diaphragm is made of metal, it is heavy and therefore has the problem of reduced sensitivity.

Therefore, an object of the present invention is to provide a speaker with flat frequency characteristics and good sensitivity.

[Means to solve the problem]

A speaker according to the present invention includes a diaphragm having an annular conductive part, a power supply coil disposed to face the conductive part with a predetermined gap, and a magnetic circuit to which the power supply coil is attached. The conductive portion is formed of a conductive polymer material.

[Effect]

When an alternating current as an audio signal is passed through the power supply coil, alternating magnetic flux is generated. Since the annular conductive part has good conductivity and is closely linked to the above-mentioned alternating current magnetic flux,
In the conductive part, induced currents of the same frequency are induced due to mutual induction phenomenon. The induced current in the conductive portion acts on the DC magnetic field at the position of the magnetic gap to excite the diaphragm.

A diaphragm formed from a polymer material has relatively large mechanical loss and is lightweight, so it can eliminate resonance peaks in the frequency characteristics of the speaker and flatten the frequency characteristics of the speaker. . Furthermore, since the diaphragm is light, the sensitivity of the speaker can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a dome-shaped speaker as shown in FIG.

FIG. 1 shows an embodiment of a speaker according to the present invention. In the configuration shown in FIG. 1, the speaker 1 is
It is mainly composed of a diaphragm 2, a damper 9, a primary feeding coil 3, a plate 4, a magnet 5, and a yoke plate 6.

An annular conductive portion 8 is provided at the opening edge 7 of the dome-shaped diaphragm 2.
is formed. The diaphragm 2 is entirely composed of a conductive polymer film. This conductive polymer film is made by incorporating carbon or metal powder into the polymer film, for example, by doping a polyacetylene base with iodine to make it conductive. This diaphragm 2 has a conductive part 8
is positioned within the magnetic gap 10 and is supported by the damper 9 so as to be able to freely vibrate. The above-mentioned magnetic gap 10 is
It is formed in an annular shape between the plate 4 and the pole piece 11 of the yoke plate 6.

The damper 9 has spring properties and is formed in an annular shape. This damper 9 has an inner circumferential side connected to the periphery of the conductive part 8 and an outer circumferential side fixed onto the plate 4.

The primary feeding coil 3 electrically couples the annular conductive portion 8 by mutual induction, and is disposed opposite to the conductive portion 8 with a predetermined gap therebetween. This primary feeding coil 3 is disposed facing a position corresponding to the outer periphery or a position corresponding to the inner periphery of the conductive portion 8.
The secondary feeding coil 3 is fixed to an example end surface 12 of the plate 4 so as to correspond to the outer periphery of the annular conductive portion 8 . Further, when the primary feeding coil 3 is provided at a position corresponding to the inner circumference of the conductive portion 8, it is fixed to the outer circumference 13 side of the pole piece 11. Note that the primary feeding coil 3 may be provided both at a position corresponding to the outer periphery or at a position corresponding to the inner periphery of the conductive portion 8.

The plate 4, magnet 5, yoke plate 6, and pole piece 11 constitute a magnetic circuit. That is,
As shown in FIG. 1, a magnet 5 is fixed to the outer periphery of the yoke plate 6, and the plate 4 is fixed to the outer periphery of the magnet 5. A magnetic circuit is formed along a path such as from the magnet 5 to the plate 4 and from the magnet 5 to the yoke plate 6 and the pole piece 11 across the magnetic gap 10.

Next, the operation of the speaker 1 will be explained.

When an alternating current as an audio signal is passed through the primary feeding coil 3, an alternating current magnetic flux corresponding to the input waveform is generated.The annular conductive portion 8 has good electrical conductivity and is closely linked to the above-mentioned alternating magnetic flux. Since they intersect, induced currents of the same frequency are induced in the conductive portion 8 due to a mutual induction phenomenon. Since the conductive portion 8 is located within the magnetic gap 10, a force proportional to the product of the strength of the DC magnetic field in the magnetic gap lO and the induced current acts on the conductive portion 8, that is, The induced current in the conductive portion 8 interacts with the DC magnetic field within the magnetic gap 10 to directly drive the diaphragm, thereby emitting sound waves.

The diaphragm 2 made of a conductive polymer film has a relatively large mechanical loss and is light, so it does not cause resonance peaks in the frequency characteristics. Therefore, the frequency characteristics of the speaker l becomes flat. Furthermore, since the peak of resonance is eliminated, damping of the diaphragm 2 becomes easier. These things improve the sound quality. Also, the diaphragm 2
Since it is light, the sensitivity of the speaker 1 can be improved. Since the diaphragm 2 is made of a polymer material, molding of the diaphragm 2 is extremely easy.

These provide excellent frequency characteristics and good sound quality.

In this speaker 1, the diaphragm 2 as a vibration system and the primary feeding coil 3 as a fixed side are mechanically separated but electrically coupled by mutual induction.
It can be operated without disposing conventional voice coils, voice coil bobbins, lead wires, etc.

Therefore, since the conductive portion 8 as a driving force generating portion can be integrally formed with the diaphragm 2, all problems associated with their coupling can be solved.

In other words, cutting of the lead wire, generation of abnormal noise due to resonance of the lead wire, interference with linearity due to the lead wire and generation of sound distortion, indirect transmission of driving force by voice coil adhesive, voice coil This solves problems such as wire breakage due to heat and carbonization of the voice coil bobbin. This provides excellent vibration characteristics and sound quality.

In this embodiment, a dome-shaped speaker is used as an example, but the present invention is not limited to this, and it goes without saying that the present invention can also be applied to a cone-shaped speaker. Further, although the illustrated examples are all external magnet types in which the magnet 5 is arranged on the outer periphery, it goes without saying that the present invention can also be similarly applied to an internal magnet type in which the magnet 5 is arranged in the pole piece 11. Further, in the illustrated example, the diaphragm 2 and the damper 9 are formed separately, and the damper 9 is connected to the conductive part 8, but the present invention is not limited to this. For example, the damper 9 can be connected to the conductive part 8. It may be formed integrally.

〔Effect of the invention〕

According to this invention, since the diaphragm is made of a conductive polymer material, the mechanical loss of the diaphragm is relatively large and the diaphragm is light. As a result, the resonance peak in the frequency characteristics of the speaker can be eliminated, and the frequency characteristics of the speaker can be made even more flat. Since the peak of resonance is eliminated, there is an effect that damping of the diaphragm becomes easier. These effects have the effect of improving sound quality.

Furthermore, since the diaphragm is light, it has the effect of improving the sensitivity of the speaker.

Furthermore, since the diaphragm is made of a polymer material, the diaphragm can be easily molded.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a frequency characteristic diagram showing an example of the frequency characteristics of a conventional speaker. Explanation of main symbols in the drawings 1: Speaker, 2: Diaphragm, 3: Primary feeding coil, 4 Nibrate, 5: Magnet, 6: Yoke plate, 8: Conductive part, 11: Pole piece. Agent Patent Attorney Masatoshi Sugiura

Claims (1)

[Scope of Claims] A diaphragm having an annular conductive part, a power supply coil disposed to face the conductive part with a predetermined gap, and a magnetic circuit to which the power supply coil is attached; A speaker characterized in that the plate and the conductive portion are made of a conductive polymer material.