JPH0388500A - Speaker equipment - Google Patents

Abstract

PURPOSE:To apply proper electromagnetic damping to a vibration system of a speaker driven with a constant current with simple constitution by arranging a damping coil provided integrally with a vibration system of a dynamic speaker into the gap of a damping use magnetic circuit independently of a speaker magnetic circuit and terminating both ends of the damping coil with an optional impedance. CONSTITUTION:A damping coil 23 is provided integrally with a vibration system of a dynamic speaker 10 and a damping magnetic circuit 25 is provided independently of a magnetic circuit 15 of the speaker 10 and the damping coil 23 is arranged in the magnetic gap of the damping magnetic circuit 25. Then both ends of the damping coil 23 are terminated by an optional impedance 29. Thus, the vibration system of the speaker of constant current drive is subjected to electromagnetic damping properly with simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a speaker device suitable for constant current drive.

[Summary of the invention]

This invention provides a speaker device in which an electrodynamic speaker is driven by a constant current amplifier, in which a braking coil provided integrally with the vibration system of the speaker is placed in the air gap of a braking magnetic circuit independent of the speaker's magnetic circuit. In addition, by terminating both ends of the braking coil with an arbitrary impedance, the vibration system of the speaker can be appropriately electromagnetically damped with a relatively simple configuration.

[Conventional technology]

Conventionally, electrodynamic speakers have generally been driven using a constant voltage method.

In the case of a normal direct radiation type speaker, its electrical impedance is at the bass resonance frequency f, as shown by the solid line in FIG. 5B. It reaches a maximum value at , and gradually increases at high frequencies.

Therefore, when such a speaker is driven at a constant voltage, the drive current increases at the bass resonance frequency f, as shown by the broken line in Figure B.
It takes a minimum value at 0 and gradually decreases in the high range. With this drive current, an output sound pressure frequency characteristic as shown in A in the same figure is obtained.

In the case of constant voltage drive, the output impedance of the signal source is zero, so the damping factor is infinite, and the vibration system of the speaker is generally sufficiently damped.

[Problem to be solved by the invention]

As is well known, a force proportional to the current flowing through the voice coil is applied to the vibration system of a dynamic speaker according to Fleming's left-hand rule.

For this reason, when a speaker like the one described above is driven by a constant current signal source with infinite output impedance, even though it should originally be driven using a constant current method, current distortion is often removed due to the nonlinear reaction of the magnetic circuit. At the same time, there is no noticeable increase in resistance caused by heat generation in the voice coil.

However, in this case, the frequency f. There is a problem in that the output sound pressure level increases in the vicinity of and in the high range corresponding to the increase in electrical impedance, which impairs the fidelity of the reproduced sound.

Furthermore, there is a problem in that the damping factor becomes zero and sufficient damping is not applied to the vibration system.

In order to solve such problems, conventionally, a constant current drive speaker or system has been constructed by adding an appropriate braking resistance to a mechanical system or an acoustic system.

However, in this case, there is a problem in that the mechanical configuration of the speaker system is complicated.

In view of this, an object of the present invention is to provide a speaker device that has a relatively simple configuration and is capable of appropriately electromagnetically damping the vibration system of a constant current driven speaker.

[Means to solve the problem]

The present invention provides a speaker device in which an electrodynamic speaker (lO) is driven by a constant current amplifier (1), in which a braking coil (23) is provided integrally with the vibration system of the speaker, and a magnetic circuit (15) of the speaker is provided. ) A braking magnetic circuit (25) is provided independently of the braking magnetic circuit, and a braking coil is disposed in the magnetic gap of this braking magnetic circuit, and both ends of the braking coil are terminated with an arbitrary impedance (29). This is a speaker device with a built-in design.

[Effect]

According to this invention, the vibration system of a constant current driven speaker is appropriately electromagnetically damped with a relatively simple configuration.

〔Example〕

Hereinafter, one embodiment of a speaker device according to the present invention will be described with reference to FIGS. 1 and 2.

The structure of one embodiment of this invention is shown in FIGS. 1 and 2.

(10) is a dynamic speaker in which the center part of a cone-shaped diaphragm (11) and a bobbin (12) are glued together, and a voice coil (13) is attached to one end (12a) of this bobbin (12). rolled around. The peripheral edge of the diaphragm (11) is glued to one end of the frame (14). (15) is a magnetic circuit, which includes a magnet (16), a pole (17) and a plate (18), and is fixed to the other end of the frame (14), and the voice coil (13) is connected to the pole. (
17) and the plate (18) coaxially.

(20) is an electromagnetic braking system, in which a braking coil (23
) is wound, and a braking magnetic circuit (25) including a magnet (26) is provided surrounding this coil (23), and the coil (23) is connected to a pole (27) and a plate (28).
placed in the space between. (24) is the supporting part profit.

As shown in Figure 2, the voice coil (13) is connected to a drive amplifier shown as a constant current source (1), and a semi-fixed resistor (29) is connected to the braking coil (23). Instead of the resistor, an appropriate impedance having frequency characteristics may be connected.

Drive current i to the voice coil (13) of the speaker (10)
When +o is supplied, the diaphragm (11) and bobbin (12)
.

The voice coil (13) vibrates as one, and along with this,
The coil (23) at the other end (12b) of the bobbin (12) also vibrates within the magnetic circuit (25). And the coil (23
), according to Fleming's right-hand rule, an electromotive force e is generated in proportion to its length, vibration speed, and magnetic flux density of the magnetic circuit (25), and this electromotive force e and the resistor (29) A current of 12° determined by the resistance value R29 flows. This current Lo generates a force in the opposite direction to the vibration direction of the bobbin (12) due to its interaction with the magnetic circuit (25).

This force is transmitted to the diaphragm (11) via the bobbin (12), and the diaphragm (11) is appropriately damped.

Note that this braking current Lo is also a detection current corresponding to the movement of the vibration system of the speaker (10), so it is used as a signal fi.
By returning to (1) and performing motional feedback, the motion of the vibration system can be controlled to achieve the desired sound reproduction characteristics.

Next, another embodiment of the speaker device according to the present invention will be described with reference to FIGS. 3 and 4.

The structure of another embodiment of the invention is shown in FIGS. 3 and 4. In both figures, parts corresponding to those in FIGS. 1 and 2 are given the same reference numerals.

In FIG. 3, a fixed coil (22) is provided in the braking system (201) to face the braking coil (23).

This coil (22) is connected to a magnetic circuit (25) as shown in the figure.
) may be wound around the outer circumference of the ball (27), or
Play 1 - It may be placed on the inner peripheral surface of (28).

In this embodiment, the braking coil (23) is short-circuited as shown in FIG. The rest of the structure is listed in 1 above.
This embodiment is similar to the embodiment shown in FIGS.

In this embodiment, a relatively large braking current 1233 is obtained by dividing the electromotive force e generated in the coil (23) by the resistance (if'frz3) of the coil (23), and the diaphragm (1
1) is sufficiently braked.

Furthermore, motional feedback can be easily performed using the electromotive force electromagnetically induced in the fixed coil (22).

〔Effect of the invention〕

As detailed above, according to the present invention, a braking coil integrated with the vibration system of an electrodynamic speaker is disposed in the gap of a braking magnetic circuit independent of the magnetic circuit of the speaker, and A speaker device is obtained in which the system can be appropriately electromagnetically braked at both ends of the braking coil.

[Brief explanation of drawings]

1 and 2 are a sectional view and a block diagram, respectively, showing the configuration of a main part of an embodiment of a speaker device according to the present invention, and FIGS. 3 and 4 are a main part of another embodiment of the invention, respectively. FIG. 5 is a sectional view and a block diagram showing the structure of the present invention, and FIG. 5 is a characteristic curve diagram for explaining the present invention. (1) is a constant current source, (10) is a speaker, (13) is a voice coil, (15), (25) is a magnetic circuit, (20
), (2OA) is an electromagnetic braking system, (22) is a pickup coil, (23) is a control coil, and (29) is a braking resistor. Agent Hidemori Matsukuma

Claims (1)

[Claims] 1. In a speaker device in which an electrodynamic speaker is driven by a constant current amplifier, a braking coil is provided integrally with the vibration system of the speaker, and the braking is performed independently of the magnetic circuit of the speaker. A speaker device comprising: a magnetic circuit for braking; the braking coil is disposed in a magnetic gap of the magnetic circuit for braking; and both ends of the braking coil are terminated with arbitrary impedance. 2. The speaker device according to claim 1, wherein a fixed pickup coil is provided in the braking magnetic circuit, and the electromotive force generated in the fixed pickup coil is fed back to the constant current amplifier.