JPS5831158B2 - speaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a speaker with a wide linear range of voice coil driving force.

FIG. 1 shows a conventional speaker.

In FIG. 1, 1 is a yoke, and a center pole 2 is integrally formed at the center of the upper surface of the yoke 1. As shown in FIG.

Reference numeral 3 denotes an annular magnet fixed to the upper surface of the yoke 1, and an annular yoke 4 is fixed to the upper surface of the magnet 3.

An annular magnetic gap is formed between the inner peripheral surface of the yoke 4 and the outer peripheral surface of the center pole 2.

Reference numeral 5 indicates a frame fixed to the upper surface of the yoke 4, and 6 indicates a diaphragm. The outer peripheral portion of the diaphragm 6 is supported by the frame 5 via an edge member.

A coil bobbin 7 is fixed to the center of the diaphragm 6, and a voice coil 8 is wound around the coil bobbin 7.

The voice coil 8 is placed in the magnetic gap.

9 is a damper. In FIG. 1, when a signal is applied to the voice coil 8, a driving force 7 acts on the voice coil 8, causing the coil bobbin 7 and the diaphragm 6 to vibrate together.

The above-mentioned driving force F becomes F=iB, where the current flowing through the voice coil 8 is i1 and the magnetic flux density of the magnetic gap is B.

Figure 2 shows the relationship between the magnetic flux density B at each point in the magnetic gap, and the magnetic flux density B at positions above and below the magnetic gap between the yoke 4 and the center pole 2.
becomes smaller.

Therefore, if the voice coil 8 is dislocated above or below the magnetic gap, the driving force F becomes small, and the linearity of the driving force F breaks down, causing distortion.

The present invention eliminates the above-mentioned conventional drawbacks and provides a speaker in which the range of linearity of the driving force F can be expanded.

A feature of the present invention is to provide a speaker in which the resistance of the voice coil 8 decreases and the driving force F remains constant at a location where the magnetic flux density 8 decreases in the magnetic gap portion.

That is, in the present invention, when the voice coil 8 is displaced to a location where the magnetic flux density B is small, its resistance decreases, and the current i flowing through the voice coil 8 is increased as shown in FIG. 3 to keep the driving force F constant. This is what we are trying to do.

FIG. 4 shows a part of the voice coil of the speaker of the present invention.

In FIG. 4, 10 is a compound semiconductor (In5b).

i is the direction of current flow, and B is the direction of magnetic flux.

In this case, an electric field E is generated in the X direction.

The direction of this electric field E is determined depending on whether the semiconductor is an N-type semiconductor or a P-type semiconductor.

If the velocity of the carrier in the presence of the electric field E is V, then ■2 μE μ: Electron mobilityHere, the carrier advances while colliding with the lattice points, and the average acceleration in the direction of the electric field is the lifetime τ Then, ■:eE/m0
τ e: Charge m: Effective mass These relationships hold true in a normal conductor, and in a normal conductor, it is constant over the life τ, so it is μ” e /rn ”τ.

Here, when a magnetic field is applied, carriers are subjected to a force due to the magnetic field, their course is bent, and the number of collisions with lattice points increases.

In this case, since the mean free path is constant, τ decreases, and as a result μ also decreases.

Therefore, the conductivity σ is σ=neμ n: number of carriers Therefore, the conductivity σ decreases and the resistance increases.

FIG. 5 shows (resistance change Jρ)/(original resistance ρ) versus magnetic flux density B of a compound semiconductor (In5b).

), and as the magnetic flux density B decreases, the resistance decreases.

Therefore, part or all of the voice coil is
When the voice coil is formed above and below the magnetic gap and the magnetic flux density B decreases, the resistance of the voice coil decreases, the current flowing through the voice coil increases, and the driving force F remains constant. .

Note that it is not limited to the above-mentioned InSb, but also GaAs and GaSb.

If part or all of the voice coil is formed of a semiconductor such as InAs, Ge, Si, etc., the linear range of the driving force can be expanded.

As described above, according to the present invention, due to the magnetoresistive effect of the semiconductor, the current flowing through the voice coil changes according to changes in the strength of the magnetic field, the driving force becomes constant, and the linear range of the driving force is expanded. It has the following.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a general speaker, Figure 2 is a diagram showing the magnetic flux density in the magnetic gap of the same speaker, Figure 3 is a diagram showing the change in current with respect to the displacement of the voice coil of the speaker of the present invention, and Figure 4. 5 is a diagram showing the principle of the magnetoresistive effect of the present invention, and FIG. 5 is a diagram showing the relationship between the magnetoresistive effect and magnetic flux density of a semiconductor (InSb). 1...Yoke, 2...Center pole, 3...Magnet, 4...Yoke,
5...Frame, 6...Diaphragm, 7.
... Coil bobbin, 8 ... Voice coil, 9 ... Damper 10 ... Semiconductor.

Claims (1)

[Claims] 1. In a speaker in which a voice coil is arranged in a magnetic gap, part or all of the voice coil is formed of a semiconductor having a magnetoresistive effect, and the resistance of the voice coil is changed according to the magnetic flux density of the magnetic gap. Featured speakers.