JPH1127785A - Speaker protection circuit and attenuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a limiting resistor of a substrate for separate mounting, to save space and to reduce production costs by forming an attenuator with a flexible resistor that is pasted to a damper holding a voice coil and limiting overcurrent that flows to the voice coil. SOLUTION: A voice coil bobbin 6 is fixed to dampers 4 and 5 which are made of two sheets of corrugation, and to a diaphragm 7. The dampers 4 and 5 have their circumferences fixed to a frame 1 and support the bobbin 6, so that a part of a voice coil 6a may be located at a magnetic gap of a magnetic circuit. Two elastic conductive materials are pasted on the damper 5 and connects both ends of the coil 6a and a terminal 10. An elastic resistor is pasted to the damper 4, one end of it is connected to the one end of the coil 6a, and the other end is connected to a terminal 9. Thus, the effect of outgoing heat radiation is increased because of the vibrations of the damper 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a speaker protection circuit and an attenuator, and more particularly to a speaker protection circuit and an attenuator using a conductor and a resistor attached to a damper holding a voice coil.

[0002]

2. Description of the Related Art An example of a conventional speaker protection circuit is shown in FIGS. A circuit is formed by soldering the resistor 13 and the overcurrent switch 11 to the printed circuit board 12,
The input terminals 16 and 16 and the output terminals 17 and 17 are connected. The input terminals 16, 16 are connected to the output side of the speaker amplifier, and the output terminals 17, 17 are connected to the voice coil 14 of the speaker as shown in the circuit diagram of FIG. One line on the output side of the speaker amplifier is connected to the voice coil 14 via a parallel circuit of the resistor 13 and the overcurrent switch 11.

When an overcurrent flows through the voice coil 14, the overcurrent switch 11 opens to supply the current to the voice coil 14 via the resistor 13, and the magnitude of the current is limited to protect the speaker.

FIG. 8 shows another example of a conventional speaker protection circuit.
(A) and (b). In this example, wires are drawn from both ends and the middle of the voice coil 15, and the wire from the middle is connected to one of the voice coil wires via the overcurrent switch 11. The wires on both sides of the voice coil are connected to the output side of the speaker amplifier. When an overcurrent flows through the voice coil 15, the overcurrent switch 11 opens to increase the impedance of the voice coil 15,
The magnitude of the current is limited to protect the speaker.

[0005]

The prior art shown in FIGS. 6 and 7 has a problem that the addition of the resistor 13 to the printed circuit board 12 increases the size and becomes very expensive.

In the device shown in FIG. 8, it is difficult to lead out the lead wire from the viewpoint of manufacturing, and the manufacturing cost increases. Also,
When the protection operation is not performed, a back electromotive force is generated in the voice coil short-circuited by the overcurrent switch 11, and the coil in the short-circuited portion becomes a mere heavy load, lowering the sound pressure level and causing deterioration of sound quality. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to use a resistor attached to a damper to reduce the manufacturing cost without attaching the resistor to a printed circuit board. It is an object of the present invention to provide a speaker protection circuit that reduces the cost and does not generate a back electromotive force in the voice coil.

It is another object of the present invention to provide a speaker attenuator whose manufacturing cost is reduced by using a resistor attached to a damper.

[0009]

A speaker protection circuit according to the present invention comprises a conductor and a resistor attached to a damper holding a voice coil, and a switch which is opened by overcurrent.

In the above speaker protection circuit,
Two dampers for holding a voice coil are provided, and the conductor and the resistor are attached to each of the dampers.

The speaker attenuator according to the present invention comprises a resistor attached to a damper for holding a voice coil.

[0012]

Embodiments of the present invention will be described with reference to the drawings. 1 to 3 show a first embodiment of the present invention. FIG. 1 shows a cross section of a speaker unit to which the present invention is applied. In the frame 1 shown in FIG.
The magnetic circuit constituted by the yoke 2 is fixed. The voice coil bobbin 6 around which the voice coil 6a is wound is fixed to the two corrugated dampers 4 and 5 and the diaphragm 7. Frame 1 around the damper 5
And the periphery of the damper 4 is fixed to the frame 1 via a spacer 8. Edge 7 around diaphragm 7
It is fixed to the frame 1 via a.

In this manner, the voice coil bobbin 6 is supported such that the voice coil 6a is located in the magnetic gap of the magnetic circuit. Terminals 9 and 10 serving as input terminals to the speaker are fixed to the spacer 8 and the frame 1, respectively.

As shown in FIG. 2A, a flexible resistor 4a is attached to the damper 4. As shown in FIG. 2B, flexible conductive materials 5a and 5a are attached to the damper 5. Although not shown, one end of each of the conductive members 5a and 5a and the resistor 4a is connected to a terminal of the voice coil 6a by a lead wire along the voice coil bobbin. The other end of the resistor 4a is connected to the terminal 9, and the conductive material 5
The other ends of the terminals a and 5a are connected to the terminal 10.

FIGS. 3A and 3B show a circuit for connecting the + output terminal and the-output terminal of the speaker amplifier to the voice coil 6a. 3 (b), the + terminal and the-terminal of the terminal 10 are not connected. In the speaker protection circuit thus configured, the voice coil 6a is normally connected via the overcurrent switch 11 and the conductor 5a.
When an overcurrent flows through the voice coil 6a, the overcurrent switch 11 opens to supply the current to the voice coil 6a via the resistor 4a, thereby limiting the magnitude of the current. The speaker is protected. At this time, although the resistor 4a generates heat, the resistor 4a is attached over a wide range of the damper 4, and the damper 4 vibrates, so that the heat radiation effect is large and overheating is suppressed.

FIGS. 4 and 5 show a second embodiment of the present invention. In this example, only one damper 4 is used instead of the dampers 4 and 5 in the speaker structure shown in FIG. As shown in FIG. 4, resistors 4a, 4a are attached to the damper 4, and the inner peripheral sides of the resistors 4a, 4a are connected to the resistors 4b attached to the damper 4, respectively. It is connected to the voice coil by a lead wire along the voice coil bobbin. The outer peripheral sides of the resistors 4a, 4a are connected to the input terminals of the speaker.

The circuit of the speaker attenuator thus formed is shown in FIG. The input power of the voice coil 6a is limited by the resistors 4a, 4a, and 4b, and the resistors 4a, 4a, and 4b generate heat. However, since the resistors 4a, 4a, and 4b are adhered over a wide range of the damper 4, the damper 4 vibrates. The heat radiation effect is large, and overheating is suppressed.

[0018]

According to the speaker protection circuit of the present invention, since the resistor is not provided on the printed circuit board, the space can be saved, and the manufacturing cost can be reduced. Further, since there is no coil of a closed circuit for generating a back electromotive force, there is no deterioration in sound quality. Furthermore, when two dampers are used, the function of holding the voice coil at the center is enhanced,
Further, according to the speaker attenuator of the present invention, which has improved mechanical durability, the resistor is not provided on the printed circuit board, so that the space can be saved and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a speaker protection circuit according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a part of the speaker protection circuit.

FIG. 3 is a circuit diagram showing the speaker protection circuit.

FIG. 4 is a plan view showing a part of a speaker attenuator according to a second embodiment of the present invention.

FIG. 5 is a circuit diagram showing the speaker attenuator.

FIG. 6 is a side view showing an example of a conventional speaker protection circuit.

FIG. 7 is a circuit diagram showing the speaker protection circuit.

FIG. 8A is a perspective view showing another example of a conventional speaker protection circuit, and FIG. 8B is a circuit diagram showing the speaker protection circuit.

[Explanation of symbols]

 Reference Signs List 1 frame 2 yoke 3 magnet 4 damper, 4a resistor 5 damper, 5a conductive material 6 voice coil bobbin, 6a voice coil 7 diaphragm, 7a edge 8 spacer 9 terminal 10 terminal 11 overcurrent switch 12 printed circuit board 13 resistor 14, 15 voice Coil 16, 17 Input terminal

Claims (3)

[Claims] 1. A speaker protection circuit comprising a conductor and a resistor attached to a damper holding a voice coil, and a switch that is opened by overcurrent. 2. The speaker protection circuit according to claim 1, wherein two dampers for holding a voice coil are provided, and the conductor and the resistor are attached to each of the dampers. 3. A speaker attenuator comprising a resistor attached to a damper for holding a voice coil.