JPS599513Y2 - electroacoustic transducer - Google Patents

Description

[Detailed Description of the Invention] The present invention provides an electroacoustic transducer with good conversion efficiency and productivity.

An example of a conventional structure of this type of converter is shown in FIG.

In Fig. 1, 1 is a permanent magnet, 2 is a yoke of the magnetic circuit, 3 is a gap in the magnetic circuit, 4 is a coil that carries an AC signal current, 5 is a soft magnetic pole piece, 6 is a diaphragm, 7 is a case,
8 is a spacer in which the vibrating membrane 6 is inserted between the cases.

9 is the center pole of yoke 2.

As shown in Figure 1, a magnetic circuit is constructed with a permanent magnet 1 and a yoke 2, a gap 3 is provided, and a coil 4 is wound around the AC.
A signal current of

Direct current magnetic flux due to the permanent magnet 1 and alternating current magnetic flux due to the signal current flow through the magnetic circuit.

In the gap 3, DC+AC magnetic flux flows, and at the same time, leakage magnetic flux is generated on the upper surface of the gap 3.

This leakage magnetic flux reaches the magnetic pole piece 5 and excites the magnetic pole piece 5.

However, in this configuration, most of the magnetic flux flows through the gap 3, and the leakage magnetic flux on the top surface of the gap is extremely small.
The electrode conversion efficiency was poor.

In addition, the construction of the gap 3 required a narrow gap to be uniformly formed, and it was time-consuming to insert a spacer during manufacturing and remove the spacer after assembling the magnetic circuit.

The present invention aims to provide an electroacoustic transducer with good electromagnetic conversion efficiency and good productivity.One embodiment of the present invention will be described below with reference to the drawings.

An embodiment of the present invention is shown in FIG.

Components that are the same as those in FIG. 1 are given the same numbers and their explanations will be omitted.

The feature of the present invention is that a conductive spacer 10 is inserted into the gap 3.

The structure of the conductive spacer 10 is preferably made of Cu, for example, to match the gap 3, and fitted onto the yoke 2 and the center pole 9 when assembling the magnetic circuit.

With such an assembly, the accuracy of the conductive spacer 10,
If the yoke 2 and center pole 9 are made with sufficient accuracy, the gap can be made uniform, which was difficult with conventional assembly.
Assembling accuracy can be improved, such as by eliminating center deviation and flattening the upper surfaces of the center pole 9 and yoke 2.

Therefore, in the conventional example, non-uniformity of the magnetic field occurs due to non-uniformity of the gap 3, vibration of the center, etc., and when the gap 3 is narrowed, one-sided attraction occurs, but with the structure of the present invention, such problems can be avoided. Therefore, an efficient converter can be constructed without any problems.

Further, in the electromagnetic converter, as described above, since the magnetic flux leaking from the upper surface of the gap 3 is utilized, it is desirable to increase the leakage magnetic flux from the upper surface of the gap 3.

In the present invention, the gap 3 is filled with a conductive material to increase leakage magnetic flux.

As mentioned above, a magnetic flux of 10 or 10 volts of direct current flows through the magnetic circuit.

The conductive material inserted into the gap 3 of the magnetic circuit has no effect on the DC magnetic field, but it does not affect the AC magnetic field (signal).
An eddy current is generated against the magnetic field, and this eddy current generates a magnetic field.

This magnetic field acts to strengthen the leakage magnetic field on the upper surface of the gap 3, and can effectively generate leakage magnetic flux with respect to the alternating current magnetic field.

The situation is shown in Figure 3.

3A shows a conventional air gap, FIG. 3B shows a case where a conductive spacer 10 is inserted into the gap of the present invention, and FIG. 3C shows a state in which a magnetic field is applied to the conductive spacer 10 to generate a demagnetizing field.

In the conventional air gap 3, leakage magnetic flux occurs in a semicircular shape (dotted line) as shown in figure a, but when the conductive spacer 10 is inserted as in the present invention, the magnetic flux in the gap 3 forms a steep mountain shape (dotted line). Measure.

As shown in C, when a magnetic field is applied to the conductive spacer 10 in the direction of the dotted arrow, a current flows in the conductor in the direction of the arrow A, and this current generates a magnetic field in the direction of the dotted arrow B.

Therefore, within the gap, a magnetic field is generated in the opposite direction to the magnetic field applied from the outside, forming a gap with high magnetic resistance, and the magnetic field becomes sharp as shown in diagram b.

The fact that the peaks of the leakage magnetic flux become sharp in this way allows the leakage magnetic flux of the gap to be effectively taken out to the outside.

Conventionally, the magnetic flux flowing from the yoke angle of the gap portion to the center pole angle could not be utilized because it was not possible to bring the magnetic pole pieces and the center pole sufficiently close together, but it can be effectively utilized by doing as in the present invention.

As described above, the present invention has good electroacoustic conversion efficiency,
Moreover, it is possible to obtain an electroacoustic transducer with good productivity.

[Brief explanation of drawings]

Fig. 1 is a sectional front view of a conventional electroacoustic transducer, Fig. 2 is a sectional front view of an electroacoustic transducer according to an embodiment of the present invention, and Fig. 3 a, l), and c are illustrations of the transducer. This is a diagram for 1...Permanent magnet, 2...Yoke, 3.
...Gap, 4...Coil, 5...
...Magnetic pole piece, 9... Center pole, 10.
... Conductive spacer.

Claims (1)

[Scope of utility model registration request] In order to utilize the magnetic field, a magnetic circuit with a gap is constructed using a permanent magnet and a yoke, a coil is installed in this magnetic circuit, a signal current is passed through it, and a DC magnetic field and an AC magnetic field are applied in parallel.
An electroacoustic transducer in which a conductive spacer is inserted into the gap of a magnetic circuit in an electromagnetic transducer that vibrates a vibrating element using leakage magnetic flux in the gap.