JPH06205493A - Device for extracting vibrational displacement of speaker unit - Google Patents

Abstract

PURPOSE:To accurately extract a displacement of a vibration part of a speaker with simple configuration. CONSTITUTION:A conductive bobbin 46 and a cone 62 are vibrated in the direction of the arrow mark A in response to an electric signal inputted to a voice coil 48 wound on the bobbin 46 of a cone speaker unit 20. A fixed electrode 66 is fixed in the bobbin 46 along the lengthwise direction confronting with the bobbin 46 with an interval. The opposite area between the bobbin 46 and the fixed electrode 66 is fluctuated by the vibration of the bobbin 46, and a capacitance of a capacitor comprising the fixed electrode 66 and the bobbin 46 is changed proportional to a displacement of the bobbin 46. The change is extracted through a lead wire 70 and a lead wire connecting to the bobbin 46.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration in a speaker unit in a state where an electric signal is applied to the speaker unit for a failure check of the speaker unit, a line check of the speaker system, a high quality reproduction and the like. An apparatus for extracting displacement information of a part.

[0002]

2. Description of the Related Art Conventionally, in a vibration displacement extracting device for a speaker unit, there is a device in which a microphone is arranged on the front surface or the back surface of the speaker unit and the radiated sound pressure of the speaker unit is picked up by the microphone.

Further, there is one in which another conductive type pickup is mechanically connected to the vibrating portion. That is, as shown in FIG. 6, one end of the connecting rod 10 penetrating the pole piece 8 is connected to the bobbin 4 of the cone type speaker unit 2, and the detecting bobbin 14 is connected to the other end of the connecting rod 10. The detection coil 12 is wound around the detection coil 12, and a detection magnet 16 is provided around the detection bobbin 14.

In this device, when an electric signal is input to the voice coil 20 wound around the bobbin 4, the bobbin 4 vibrates in the vertical direction in FIG. 6, and this vibration is transmitted through the connecting rod 10 to the detecting bobbin. The vibration is transmitted to the bobbin 14, and the detection bobbin 14 makes the same vibration as that of the bobbin 4. According to this vibration, an electric signal is generated in the detection coil 12, and the vibration of the bobbin 4 is detected.

There is also one that detects a change in capacitance formed by arranging the vibrating portion and the fixed electrode so as to face each other in the amplitude direction. That is, as shown in FIG. 7, in the horn type driver unit 22, a conductive diaphragm 28 coupled to a bobbin 26 around which a voice coil 24 is wound.
The fixed electrode 32 is provided on the equalizer 30 so as to be spaced in the vertical direction in FIG.

In this case, when an electric signal is input to the voice coil 24, the diaphragm 28 vibrates together with the bobbin 26, and the distance between the diaphragm 28 and the fixed electrode 32 changes in accordance with the vibration, so that the diaphragm 28 and the fixed electrode 32 change. Since the capacitance between the capacitor 32 and 32 changes, the change in the capacitance is detected to detect the vibration of the diaphragm 28.

[0007]

However, in the case where the radiated sound pressure of the speaker unit is detected by the microphone, the accuracy of the vibration displacement detection information depends on the performance of the microphone used, and also from the outside. There is a problem that it responds to the noise of. In particular, in a speaker system using a plurality of speaker units, even radiated sound from a speaker unit that is not a measurement target is collected, so that accurate measurement cannot be performed. If a microphone is placed on the front or back of the speaker unit as described above,
The microphone itself becomes an acoustic obstacle, which makes accurate measurement impossible and adversely affects the radiated sound.

In FIG. 6, since the connecting rod 10 and the detecting bobbin 14 are connected to the vibrating portion such as the bobbin 4,
There is a problem that the mass of the vibration system becomes large and the output sound pressure decreases. Also, the detected information is the speed information of the vibrating part, and when trying to know the acceleration or displacement of the vibrating part,
You have to do some processing on the detected information,
The process was troublesome. In addition, the lower the frequency of the input electric signal, the lower the sensitivity. Further, in addition to the original magnetic circuit including the magnet 34 and the like, a magnetic circuit including the detection magnet 16 and the like must be separately provided, which causes a problem that the structure becomes complicated.

Further, in the case of FIG. 7, when it is used for a large amplitude such as a woofer for low frequency reproduction, it is necessary to prevent the diaphragm 28 and the fixed electrode 32 from coming into contact with each other. Must be taken and therefore
There is a problem that the capacitance between the diaphragm 28 and the fixed electrode 32 becomes very small in a state where the diaphragm 28 is not vibrating, and when detecting a small amplitude, the S / N ratio thereof deteriorates.

[0010]

In order to solve each of the above problems, the present invention provides a speaker unit having a vibrating portion that vibrates in response to an input electric signal. A fixed electrode, which is fixedly arranged substantially parallel to the vibration direction of the vibrating portion and is opposed to the conductive portion, and a take-out means for taking out a capacitance formed between the conductive portion and the fixed electrode. Is.

The take-out means may be lead wires respectively connected to the fixed electrode and the conductive portion. Alternatively, the fixed electrode may be divided into two along the vibration direction, and lead wires may be connected to the divided fixed electrodes as extraction means.

[0012]

According to the present invention, when the vibrating portion vibrates, the conductive portion also vibrates in the vibrating direction. As a result, the facing area between the conductive portion and the fixed electrode changes, and the capacitance formed by both changes. That is, the change in displacement of the vibrating portion can be taken out as it is as the change in capacitance.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, as shown in FIG. 1, the present invention is applied to a cone type dynamic speaker unit 40 for a woofer, and an opening 44 is formed in a rear side of a frame 42. Conductive bobbin 46 concentric with 44
Are arranged. The bobbin 46 is formed of a conductive material in a cylindrical shape, and a voice coil 48 is wound around the peripheral surface thereof. The bobbin 46 is supported on the frame 42 by a spider 50.

Inside the bobbin 46, the head 54 of the pole piece 52 is disposed concentrically with the opening 44 from the rear side thereof.
Is invading. An annular magnet 58 is arranged concentrically with the head 54 on the flange 56 of the pole piece 52. Between the magnet 58 and the back surface of the frame 42,
An annular magnetic permeable plate 60 is arranged in contact with each of these. The pole piece 52, the magnet 58, and the plate 60 constitute a magnetic circuit that applies a magnetic field to the boil coil 48.

A cone 62 is attached to the tip of the bobbin 46, and the tip of the cone 62 is fixed to the frame 42 by a gasket 64. 63 is a dust cap.

In this cone type speaker unit 40,
When an electric signal is supplied to the voice coil 48, the bobbin 46 vibrates in the direction of arrow A, that is, the length direction of the peripheral wall of the bobbin 46 according to the magnitude of the electric signal, and this vibration is transmitted to the cone 62. , Radiated sound is generated.

On the head 54 of the pole piece 52, FIG.
An annular insulating plate 62 as shown in is arranged concentrically with the pole piece 52. A fixed electrode 64 as shown in FIG. 2 is arranged on the insulating plate 61. The fixed electrode 64 has a cylindrical peripheral wall portion 66 and an annular bottom portion 68 integrally formed at the lower end thereof. The insulating plate 61 is arranged so that the peripheral wall portion 66 faces the peripheral surface of the bobbin 46 with a predetermined gap and the bottom portion 68 is concentric with the bobbin 46.
It is placed on top.

A lead wire 70 is connected to the bottom wall portion 68 and is led out to the outside through a hole 72 penetrating the head portion 54 of the pole piece 52. Further, as shown in FIG. 3, the lead wire 71 is also connected to the electrically conductive bobbin 46. Both of these lead wires 70 and 71 are connected to a preamplifier (not shown). Note that, in FIG. 3, reference numerals 73 and 73 are lead wires for inputting the voice coil 48.

Since the peripheral wall portion 66 of the fixed electrode 64 and the conductive bobbin 46 are arranged so as to face each other with a constant gap therebetween, a capacitor having air as a dielectric is formed by them. When the conductive bobbin 46 vibrates as described above, the facing area between the conductive bobbin 46 and the peripheral wall portion 66 of the fixed electrode 64 changes according to the change in displacement of the vibrating portion, and is formed by both. The capacity of the capacitor also changes in proportion to the displacement of the vibrating part. That is,
The amount of change in displacement of the vibrating part is converted into the change in capacitance of the capacitor. Therefore, the displacement information can be extracted as an electric signal by connecting the lead wire 70 and the like to a preamplifier for waveform extraction.

A second embodiment is shown in FIGS. 4 and 5. In the cone type dynamic speaker unit 40a of the second embodiment, as shown in FIG. 5, the fixed electrode is composed of two split members 64a and 64b. These dividing members 64a and 64b are obtained by dividing the fixed electrode 64 of the first embodiment into two along the lengthwise direction of the peripheral wall portion 66 thereof, and the peripheral wall portions 66a and 66b and the bottom wall portion 6 respectively.
It has 8a and 68b.

The dividing members 64a and 64b are arranged on the insulating plate 61 so as to be spaced apart from each other by a constant distance as shown in FIG. 4 and also spaced apart from the conductive bobbin 46 by a predetermined distance. . Then, each dividing member 64
Lead wires 70a and 70b are connected to the bottom wall portions 68a and 68b of a and 64b, respectively, and these lead wires 70a and 70b are connected to the preamplifier through the through holes 72 as in the first embodiment. Has been done. The other parts are configured in the same manner as in the first embodiment, and are therefore assigned the same reference numerals and explanations thereof are omitted.

In the cone type speaker unit 40a of the second embodiment, one capacitor is constituted by the peripheral wall portion 66a of the dividing member 64a and the conductive bobbin 46, and the peripheral wall of the conductive bobbin 46 and the other dividing member 64b. Part 66
Another capacitor is formed by b. Therefore, the capacitance changes in accordance with the change in the displacement of the vibrating portion of the bobbin 46 according to the input of the electric signal to the voice coil 48, as in the first embodiment.

Also, both of these capacitors are divided members 6
Since the conductive bobbin 46 is interposed between 4a and 64b, they are connected in series. Therefore, both split members 64
The capacitance can be measured only by connecting the lead wires 70a and 70b connected to a and 64b to the preamplifier. That is, the first
In the first embodiment, the lead wire has to be connected to the conductive bobbin, whereas in the second embodiment, the lead wire need not be connected to the conductive bobbin 46.

In both of the above embodiments, the present invention is applied to the cone type speaker unit, but it can also be applied to a horn type or dome type speaker unit. Further, although the fixed electrode is provided inside the conductive bobbin 46 in both of the above-described embodiments, it may be provided outside. Further, in the second embodiment, both the split members 64a and 64b are provided as the fixed electrodes, but only one may be provided depending on the case. In that case, one of the lead wires needs to be connected to the conductive bobbin 46 as in the first embodiment. Further, in the second embodiment, the fixed electrode is divided into two, but it may be divided into three or more and a part of them may be used.

[0025]

According to the present invention, the facing area between the conductive portion and the fixed electrode of the vibrating portion of the speaker unit changes in proportion to the displacement of the vibrating portion. Therefore, the capacitance of the capacitor formed by the conductive portion and the fixed electrode changes in proportion to the displacement of the vibrating portion. Therefore, it is possible to measure the displacement of the vibrating part extremely accurately simply by connecting a simple electric circuit, especially in the mid-low range where the correlation between the radiated sound and the vibration of the vibrating part is high. You can Further, since the obtained capacitance change information represents the change in the displacement of the vibrating portion as it is, no signal processing is required. Further, even if the fixed electrode vibrates at the maximum amplitude, it does not mechanically contact the vibration system of the speaker unit at all. Can be detected, and the dynamic range of displacement extraction is wide, and since only fixed electrodes are added for displacement detection, it is easy to manufacture and highly productive. In addition, the original operation of the speaker unit is not adversely affected, and the speaker unit and the fixed electrode are not damaged. Further, when the fixed electrode is divided, the extraction means only needs to be connected to each of the divided fixed electrodes, and it is not necessary to provide the extraction means on the conductive portion of the vibrating portion, which facilitates the manufacture.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a cone type speaker unit according to a first embodiment in which a vibration displacement extracting device according to the present invention is implemented.

FIG. 2 is a perspective view of a fixed electrode and an insulating plate used in the first embodiment.

FIG. 3 is a partially cutaway perspective view of an essential part of the first embodiment.

FIG. 4 is a vertical sectional side view of the second embodiment.

FIG. 5 is a perspective view of a fixed electrode used in the second embodiment.

FIG. 6 is a vertical cross-sectional side view showing a cone type speaker unit in which an example of a conventional vibration displacement extraction device is implemented.

FIG. 7 is a partially omitted vertical cross-sectional view showing a horn type speaker unit in which another example of the conventional vibration displacement extracting device is implemented.

[Explanation of symbols]

42 frame 46 conductive bobbin (conductive part of vibrating part) 62 cone (vibrating part) 64 fixed electrode 64a 64b split member (fixed electrode) 70 71 70a 70b lead wire (takeout means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Otono 7-2-1, Nakajima Nakamachi, Chuo-ku, Kobe-shi, Hyogo TOA Co., Ltd.

Claims (3)

[Claims] 1. A speaker unit having a vibrating portion that vibrates in accordance with an input electric signal, wherein a portion of the vibrating portion near the conductive portion is substantially parallel to the vibrating direction of the vibrating portion and faces the conductive portion. Fixed electrode that is fixedly arranged by
An apparatus for extracting vibration displacement of a speaker unit, comprising: a take-out means for taking out a capacitance formed between the conductive portion and the fixed electrode. 2. The vibration displacement extracting device for a speaker unit according to claim 1, wherein the extracting means is a lead wire connected to each of the fixed electrode and the conductive portion. Vibration displacement extraction device. 3. The vibration displacement extracting device for a speaker unit according to claim 1, wherein the fixed electrode is divided into two along the vibration direction, and the extraction means is attached to the divided fixed electrode. A vibration displacement extracting device for a speaker unit, wherein the lead wires are connected to each other.