JPH04196799A - Electromagnetic induction type speaker - Google Patents

Abstract

PURPOSE:To prevent occurrence of rolling by providing an electric input coil fixed to a side wall of a center pole or a magnet in a magnetic circuit and a voice coil coupled with a diaphragm and short-circuited to the speaker. CONSTITUTION:A voice coil 17 is supported in an air gap 20 by using a suspension 16 and a cone shaped diaphragm 15 and fitted to the diaphragm 15, an electric coil 19 is fixed to a side wall of a center pole 18 and an AC magnetic field penetrated through the pole 18 is generated by the law of electromagnetic induction by supplying an AC current to the coil 19. When the AC magnetic field penetrates through the short-circuited coil 17 and a current flows to the coil 17 attended with an induced electromotive force generated in the coil 17. Then a torque according to a Lorentz's force exerted between the magnetic flux in the air gap 20 and the current flowing to the coil 17 and the coil 17 drives the fixed diaphragm 15, radiates a sound wave, and then the electroacoustic transducing is implemented. Thus, the symmetry of the vibration system is improved and rolling is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electromagnetic induction speaker used in various audio equipment, video equipment, and the like.

Conventional Technology In recent years, the digitalization of audio equipment has created high-quality sources (CD, DAT, etc.) that cover the entire audio band.

etc.) have been put into practical use, but speakers that convert music signals from electrical signals to acoustic output directly feed the electrical signal input to the voice coil, which is the drive system.

Currently, the most common speaker (electro-acoustic conversion method) is an electrodynamic speaker that uses a permanent magnet.
This electrodynamic speaker is composed of a permanent magnet and a magnetic circuit having an air gap. Then, a voice coil held by a damper and a diaphragm is placed in the air gap, and when an input current is applied to this voice coil, a Lorentz force is generated between the magnetic flux in the air gap and the current flowing through the voice coil, and the voice coil A driving force acts on the diaphragm through the vibration plate, generating sound waves.

Currently, the means of electrical input to this electrodynamic speaker is a direct input method to the voice coil, which is the drive system.

Hereinafter, the conventional electrodynamic speaker as described above will be explained with reference to the drawings. FIG. 2 shows a cross section of the most common type of conventional electrodynamic loudspeaker.

In FIG. 2, 1 is a bottom plate, which has a center pole 8 in its center. 3 is the top plate;
An annular gap 9 is formed between the center pole 8 and the center pole 8.
Ru. 2 indicates a ring-shaped magnet. Bottom plate 1, center pole 8, gap 9, top plate 3,
The magnet 2 constitutes a magnetic circuit. Reference numeral 7 indicates a boyce coil held within the gap 9 by the suspension 6 and the diaphragm 5. Reference numeral 4 indicates a frame that structurally holds the diaphragm 5 and the suspension 6. The voice coil 7 is fixed to the diaphragm 5. When a current flows through the voice coil 7 held in the air gap 9, a driving force according to the Lorentz force acts between the magnetic flux in the air gap 9 and the voice coil 7, causing the diaphragm 5 fixed to the voice coil 7 to move. It is driven, a sound wave is emitted, and electro-acoustic conversion is performed.

Problems to be Solved by the Invention However, the above-mentioned conventional electrodynamic speaker has the following problems. When electrical input is applied to the voice coil 7 through the gold thread wire, the voice coil 7
It is possible that the gold thread wire breaks due to the vibration. Furthermore, the structure in which the gold thread wire is soldered to the diaphragm 5 using a stopper may cause mechanical problems, such as an increase in the mass of the oscillation system and the occurrence of rolling.

In order to solve the above-mentioned problems, the present invention has a wire having two or more turns, which is fixed to the side wall of the center ball (in the case of an internal magnetic type, it becomes a magnet) and is made of a good conductor such as copper wire. An electric input is applied to the coil, and the magnetomotive force generated therefrom causes electromagnetic induction in the voice coil, and the voice coil generates an electric signal to drive the diaphragm without using a gold wire.

Means for Solving the Problems In order to achieve the above objects, the present invention provides an electric input coil fixed to the center pole of the magnetic circuit or the side wall of the magnet, and a voice coil connected to the diaphragm and short-circuited. The structure is as follows.

Operation The present invention uses the above-described structure to apply electrical input to a coil with two or more turns, which is fixed to the center ball or the side wall of the magnet and made of a good conductor such as copper wire, and generates electricity from there. The magnetomotive force causes electromagnetic induction in the voice coil and generates an electrical signal in the voice coil without using gold wire. As a result, the vibration of the voice coil does not use gold wire, so the symmetry of the drive system is guaranteed compared to conventional electrodynamic speakers, and the grommets are used to connect the gold wire to the diaphragm. There is no need to do this, reducing man-hours and preventing rolling of the diaphragm.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 11 denotes a bottom plate, which has a center pole 18 in its center. A top plate 13 forms an annular gap 20 between it and the center pole 18.

12 indicates a ring-shaped magnet. The bottom plate 11, center pole 18, gap 20, top plate 13, and magnet 12 constitute a magnetic circuit. Reference numeral 17 indicates a voice coil held within the air gap 20 by the suspension 16 and the cone-shaped diaphragm 15. Reference numeral 14 indicates a frame that structurally holds the diaphragm 15 and suspension 16. The voice coil 17 is fixed to the diaphragm 15. Reference numeral 19 indicates an electrical input coil fixed to the side wall of the center pole 18. When an alternating current flows through this electric input coil 19, the center pole 1
8 (an alternating current magnetic field is generated. The alternating current magnetic field passes through the short-circuited voice coil 17, and a current flows along with the induced electromotive force generated in the voice coil 17. The magnetic flux in the air gap 20 and the voice coil 17 A driving force according to the Lorentz force acts between the electric current and the voice coil 17 or the diaphragm 15 fixed to it, so that a sound wave is emitted and electro-acoustic conversion is performed.

In the above embodiment, an external magnetic type magnetic circuit was explained, but it is also possible to use an internal magnetic type magnetic circuit in which a columnar magnet or a magnet and a pole piece are incorporated in the yoke to connect the electric input coil 19. It can also be configured to be fixed to the outer circumferential surface of the magnet, that is, to the side wall.

Effects of the Invention As is clear from the above embodiments, the present invention eliminates the gold thread wire and separates the electric signal input coil and drive coil.
It is possible to provide an electromagnetic induction speaker that can improve the symmetry of a vibration system and prevent rolling.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view showing the structure of an electromagnetic induction speaker according to an embodiment of the present invention, and FIG. 2 is a half-sectional view showing the structure of a conventional electrodynamic speaker. 11...Bottom plate, 12...Magnet, 13...Top plate, 14...
... Frame, 15 ... Shaking fEl board, 1
6... Suspension, 17... Voice coil, 18... Center pole, 19...
...Electric input coil, 20... air gap. Name of agent: Patent attorney Haruaki Koebi and two others Figure 1 Figure 2

Claims (1)

[Claims] It has an electrical input coil with two or more windings and is made of a good conductor such as copper wire fixed to the center pole of the magnetic circuit or the side wall of the magnet, and the short-circuited voice coil connected to the diaphragm is connected to the magnetic circuit. An electromagnetic induction speaker placed in the air gap of the circuit.