JPS6139799B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for assembling a speaker that allows the center of the winding width of a voice coil to coincide with the center of the magnetic flux density distribution of the magnetic gap of a magnetic circuit, thereby achieving excellent conversion efficiency. It is.

In general, a speaker is constructed by connecting a frame 6 to a magnetic circuit 5 composed of a plate 12 having a center pole 1, a ring-shaped magnet 3, and a ring-shaped upper plate 4, as shown in FIG. The periphery of the diaphragm 8 is fixed together with the gasket 7 to the periphery of the diaphragm 8 by adhesive or the like.
A voice coil 9 is coupled to the center of the diaphragm 8, and a damper 10 is connected to the middle of the voice coil 9.
to hold the lower coil part 9' of the voice coil 9.
is fitted into the magnetic gap 11 of the magnetic circuit 5 without eccentricity, and a dust cap 12 is attached to the upper center surface of the diaphragm 8.

In such a speaker, the conventional method of assembling the voice coil 9 into the magnetic gap 11 is to incorporate a gap gauge with the voice coil 9 attached to the outer periphery of the center pole 1, and adjust the height of the magnetic gap 11 as shown in FIG. The center is aligned with the center of the winding width of the coil portion 9' of the voice coil 9, the damper 10 is connected, and the gap is removed.

However, the center of the magnetic flux density distribution in the magnetic gap 11 does not necessarily coincide with the center of the height of the magnetic gap 11, as shown in FIG.

Therefore, in the conventional configuration in which the center of the winding width of the coil portion 9' of the voice coil 9 is made to coincide with the center of the height of the magnetic gap 11, the center of the magnetic flux density distribution and the center of the winding width of the coil portion 9' are They did not match, resulting in lower conversion efficiency and more asymmetrical distortion. Figure 4 is a characteristic diagram of a speaker with a diameter of 25 cm constructed by incorporating a voice coil 9 using the conventional method, in which a is the sound pressure frequency characteristic curve, b is the second harmonic distortion characteristic curve, and c is the third harmonic distortion characteristic curve. This is a harmonic distortion characteristic curve.

The present invention eliminates the drawbacks of the prior art as described above.

Embodiments of the present invention will be described below with reference to FIG. 5.

The center pole 1 of the magnetic circuit 5 is provided with a guide groove 13 concentric with the magnetic gap 11.

A gap gauge 14 in which a voice coil 9 is fitted on the outer peripheral surface of the center pole 1 is incorporated. This gap gauge 14 is composed of an outer cylinder 15 on which the voice coil 9 is attached, an inner cylinder 16 that fits into the guide groove 13, and a ceiling surface 17 that connects the upper surfaces of the outer cylinder 15 and the inner cylinder 16.
A screw hole 18 is provided in the center of the screw hole 1.
An adjustment screw 19 is screwed into the screw 8 .

Then, when the lead wire 20 of the voice coil 9 is connected to the DC voltmeter 21, the adjustment screw 19 is rotated left and right to move the gap gauge 14 up and down, and the voice coil 9 is also moved up and down, and the DC voltmeter 21 shows E=Bv. voltage appears. In addition,
B is the magnetic flux density of the magnetic gap 11, is the effective wire length of the voice coil, and v is the moving speed of the voice coil 9.

If the maximum point of the voltage E generated in this way is determined, it will be the position where the magnetic flux density B is maximum, assuming that the speed v and the effective line length are constant within a limited range. That is,
The voltage E becomes maximum at a position where the center of the magnetic flux density distribution and the center of the winding width of the coil portion 9' of the voice coil 9 almost coincide. In this state, damper 10,
The diaphragm 8 is combined to complete the speaker.

On the other hand, the driving force f of the speaker is f=Bi(i
is the current), so when B is maximum, the conversion efficiency is also maximum, and since the center of the magnetic flux density distribution coincides with the center of the winding width of the coil portion 9' of the voice coil 9, asymmetric distortion is also reduced. become.

That is, Fig. 6 shows a speaker with a diameter of 25 cm constructed by incorporating the voice coil according to the method described above, and the sound pressure frequency characteristics a, second harmonic distortion b, and third harmonic distortion c.
The results are shown below. In Fig. 6, when compared with the characteristics of the conventional speaker shown in Fig. 4, the sound pressure increases by 1 to 1.5 dB, and the distortion increases by 7 to 10 dB at 20 to 500 Hz.
It is clear that there has been an improvement.

As described above, according to the speaker assembly method of the present invention, it is possible to produce a speaker with high conversion efficiency and low asymmetric distortion, even if there are manufacturing variations in the magnetic flux density distribution in the magnetic circuit or in the voice coil. , it has the advantage that the center of the coil winding width of the voice coil and the center of the magnetic flux density distribution of the magnetic gap can always be aligned, and is of great industrial value.

[Brief explanation of the drawing]

Figure 1 is a half-sectional view of a typical speaker, Figure 2 is an explanatory diagram showing the relationship between the voice coil and magnetic gap assembled using the conventional assembly method, and Figure 3 is a diagram of the magnetic gap of a typical magnetic circuit. An explanatory diagram showing the magnetic flux density distribution, Fig. 4 is a characteristic diagram of a conventional speaker, Fig. 5 is a sectional view of a main part of an embodiment of the speaker assembly method of the present invention, and Fig. 6 is a diagram showing a speaker assembled by the same method. It is a characteristic diagram of a speaker. 5...Magnetic circuit, 6...Frame, 8...Diaphragm, 9...Voice coil, 9'...Coil part, 1
0...damper, 11...magnetic gear, 14...
... Gap gauge, 18 ... Screw hole, 19 ... Adjustment screw, 20 ... Lead wire, 21 ... Voltmeter.

Claims (1)

[Claims] 1. In a speaker assembly method in which a voice coil is incorporated into a magnetic gap of a magnetic circuit using a gap gauge, an adjustment screw is incorporated into the gap gauge and the gap gauge is moved up and down at a constant speed together with the voice coil attached to the outer periphery, A speaker assembly method characterized in that a voltmeter is connected to the lead wire of the voice coil, the voice coil is positioned at the maximum voltage appearing on the voltmeter, and a damper and a diaphragm are coupled.