JPH05219593A - Speaker for active noise control - Google Patents

Abstract

PURPOSE:To improve efficiency for muffling by executing control against posi tion deviation caused by the change of external pressure by preparing a voice coil while using an adhesive agent mixing ferromagnetic powder, and applying ferromagnetism to the surface of a copper wire when winding the insulated cover copper wire around a coil bobbin. CONSTITUTION:A wire 5 covering a copper conductor wire with an insulated layer is wound around a coil bobbin 6 by using an adhesive agent 7 for wire fixing, the wire is mounted, and a voice coil 8 is prepared. This adhesive agent 7 is polyamide resin solvent mixing magnetite having average particle diameter <=5mu at 50% solid ratio, a layer distributing the magnetite powder of a ferromagnetic substance is formed, and the coil 8 is made ferromagnetic. Therefore, since the coil is attracted to the line of magnetic force in magnetic gaps, the speaker can be controlled against the position deviation of a diaphragn or the coil 8 caused by the change of external pressure. Thus, the sufficient effect of active noise control can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active noise control speaker, and more particularly to an active noise control speaker for the purpose of eliminating or reducing noise generated by airflow such as exhaust gas or intake air. is there.

[0002]

2. Description of the Related Art Active noise control technology is one of the quiet technology for removing and reducing noise. Active noise control is exactly 18 against noise
The noise is dynamically removed and reduced by generating sound waves having different phases by 0 °. Therefore, the active noise control speaker for anti-phase sound wave generation is
Must be well controlled. Also, in order to improve the noise reduction efficiency, the speaker for anti-phase sound wave generation is
It is desirable to install it near the noise source.

[0003]

On the other hand, application of active noise control technology has been proposed for noise associated with airflow such as exhaust gas or intake air. However, a change in atmospheric pressure due to a change in airflow causes a speaker to change. The problem is that the position of the voice coil coupled to the diaphragm and the speaker diaphragm changes, and the voice coil cannot be held at the proper position in the magnetic gap, making it impossible to perform sufficient control required for active noise control. was there.

[0004]

A speaker for active noise control according to the present invention is characterized by imparting ferromagnetism to a wire of a voice coil suspended in a magnetic gap formed by a magnetic pole and a yoke. Is.

[0005]

In the speaker for active noise control according to the present invention, by imparting ferromagnetism to the wire of the voice coil, the voice coil portion is attracted to the magnetic lines of force in the magnetic gap, and the pressure applied from outside the speaker to the diaphragm is reduced. Regardless, it maintains the proper position of the voice coil in the magnetic gap.

[0006]

Embodiments of a speaker according to the present invention will be described with reference to the drawings.

As Example 1, as shown in FIG. 1, copper is used as the conductor wire 1, and the surface of the conductor wire 1 has about 1/1 / the diameter of the wire.
A ferromagnetic nickel layer 2 having a thickness of 10 is clad, and a surface of the nickel layer 2 is covered with an insulating layer 3 to form a wire 4. The wire 4 is wound around a coil bobbin and attached with an adhesive to form a voice coil.

The wire diameter of the conductor wire 1 is generally 0.10 to 0.17 mm, but in the present embodiment, a wire diameter of 0.11 mm was used.

As a second embodiment, as shown in FIG. 2, a conductor wire made of copper is coated with an insulating layer to form a wire 5, and when the wire 5 is wound around a coil bobbin 6, an average particle diameter is measured. Magnetite of 5 microns or less in solid content ratio of 50
% Of the polyamide resin solution mixed and dispersed is used as the wire fixing adhesive 7, and the wire 5 is wound and mounted on the coil bobbin 6 to form the voice coil 8.

The adhesive 7 is formed as a layer in which magnetite powder, which is a ferromagnetic material, is dispersed, and the voice coil 8 part becomes ferromagnetic.

As shown in the partial vertical sectional view of FIG. 3, the speaker for active noise control using the above voice coil is a support plate 9 having a pole pole 10 projecting from the center of the upper surface thereof. The magnet 11 and the upper plate 12 are sequentially placed and fixed on the support plate 9. Reference numeral 6 is a magnetic pole 10 and an upper plate (yoke)
2 is a coil bobbin suspended in a magnetic gap between the voice coil 12 and the coil bobbin 6. A voice coil 8 in which a wire is made ferromagnetic is attached to the coil bobbin 6 by winding. The inner peripheral edge of the diaphragm 13 and the damper 14 is mounted on the upper part of the coil bobbin 6, and the outer peripheral edge of the diaphragm 13 is mounted on the inner peripheral edge of the edge 16 fixed to the frame 15.

On the other hand, the attraction force due to the magnetic force of the voice coil acts as a resistance against the driving of the speaker, but at this time, the attraction force F ₁ [Newto is caused by the magnetic force of the voice coil.
[n] is represented by the following equation (1).

[0013]

F ₁ = B · A (1) Further, the driving force F ₂ [Newton] of the speaker is expressed by the following equation (2).

[0014]

F ₂ = B · I · I (2) In the above formulas (1) and (2), B is the magnetic flux density [Wb / m ² ] in the magnetic gap, and A is the cross-sectional area of the magnetic gap [ m ² ], l is the wire length [m] of the voice coil and I is the current [A]. As is clear from the above equation, the cross-sectional area of the magnetic gap in the speaker is much smaller than the wire length, and it can be seen that the resistance force of magnetic attraction does not have a large adverse effect on the driving force.

That is, even if the width of the magnetic gap is large, it is 1 m.
Therefore, the cross-sectional area of the magnetic gap is 4-5 mm ²
That is, the wire length is 4 to 5 × 10 ⁻⁶ m ² , but the wire length of the voice coil is 3 to 5 m, and in this embodiment, 4.5 m.
Therefore, it is clear that there is a large difference between the magnetic attraction and the driving force even in the numerical comparison of only this term.

A characteristic diagram of sound pressure level (SPL [dB]) vs. frequency (Frequency [Hz]) of exhaust noise due to processing by the active noise control speaker having a diameter of 8 cm manufactured in Examples 1 and 2 is shown in the figure. 4 shows characteristics (A) and (B), respectively, and the characteristic (C) is a comparative example of a speaker having the same shape using a voice coil of 67 turns with the above wire diameter. Due to the characteristics, the sound pressure level of exhaust noise is reduced.

[0017]

According to the present invention, by imparting ferromagnetism to the wire of the voice coil, the voice coil portion is attracted to the magnetic force line in the magnetic gap formed by the magnetic pole and the yoke. The speaker can be controlled against the displacement of the diaphragm or the voice coil due to the change in pressure, and a speaker showing a sufficient effect of active noise control can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a voice coil wire according to a first embodiment of the present invention.

FIG. 2 is a partial vertical sectional view of a speaker voice coil according to a second embodiment of the present invention.

FIG. 3 is a partial vertical cross-sectional view of an active noise control speaker according to the present invention.

FIG. 4 is a characteristic diagram comparing the effects of active noise control by a speaker according to the present invention and a normal speaker.

[Explanation of symbols]

 1 Conductor Element Wire 2 Nickel Layer 3 Insulating Layer 4, 5 Wire 6 Coil Bobbin 7 Wire Fixing Adhesive 8 Voice Coil 10 Magnetic Pole 12 Upper Plate (Yoke) 13 Vibration Plate

Claims (3)

[Claims] 1. An active noise control speaker having a voice coil suspended in a magnetic gap, wherein a wire of the voice coil is provided with ferromagnetism. 2. The active noise control speaker according to claim 1, wherein the conductor surface of the wire of the voice coil is coated with a ferromagnetic material by clad or electroplating to impart ferromagnetism. 3. The active noise according to claim 1, wherein the voice coil is fixed by mixing a ferromagnetic powder into an adhesive for fixing the wire and imparting ferromagnetism to the surface of the wire. Control speaker.