Speaker equipment

Abstract

To provide a high-quality and safe speaker device by avoiding the risk of dangerous accidents such as smoke and fire caused by an overcurrent continuing to flow from a voice coil through a magnetic circuit when the voice coil comes into contact with the magnetic circuit and shorts out the magnetic circuit in a structure in which the magnetic circuit of the speaker device is earthed. The speaker device includes a magnetic circuit earth terminal electrically connected to the magnetic circuit, and an overcurrent blowout protection fuse having an earth connection terminal attached thereto is connected to the magnetic circuit earth terminal to ground the earth connection terminal.

Description

[Technical field]

[0001] The present invention relates to an electrodynamic speaker device that receives an electric signal and outputs a sound wave. [Background technology]

[0002] An electrodynamic speaker is a speaker that produces sound by moving a diaphragm using electromagnetic force generated by Fleming's left-hand rule. It consists of a magnetic circuit that provides a stable magnetic field, a voice coil that moves due to the electromagnetic force generated by the flow of signal current, and a diaphragm connected to the voice coil.

[0003] In order to efficiently operate the diaphragm using the electromagnetic force acting on the voice coil when a signal current is passed through it, the voice coil must be placed in an area with high magnetic flux density, so the voice coil is placed in a narrow gap in the magnetic circuit where the magnetic field is strong.

[0004] A side effect of placing the magnetic circuit and voice coil close to each other is that the potential of the magnetic circuit can fluctuate depending on the signal current flowing through the voice coil, affecting the reproduced sound. To suppress such effects, a sound quality improvement technique is known that involves earthing the magnetic circuit in order to stabilize the potential of the magnetic circuit. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] JAS jounal September 1993 issue p-34 Sound quality improvement technology named CGR Summary of the Invention [Problem to be solved by the invention]

[0006] In order to stabilize the potential of the magnetic circuit in a speaker device and improve sound quality, if the magnetic circuit is earthed, there is a risk that if the signal current supplied to the voice coil is over-input beyond the expected level, the voice coil may deform beyond the expected specifications and come into contact with the plate of the magnetic circuit. If this happens, the voice coil that comes into contact with the plate, which is part of the grounded magnetic circuit, will short out, and in the worst case scenario, this could lead to a dangerous accident such as smoke or fire.

[0007] An object of the present invention is to provide a speaker device that is safe and has high sound quality. [Means for solving the problem]

[0008] The invention of claim 1 is a speaker device characterized in that it has an earth terminal electrically connected to a magnetic circuit including a yoke, a magnet, and a plate, one end of an overcurrent protection fuse is electrically connected to the earth terminal, and the other end of the overcurrent protection fuse is electrically grounded. The invention of claim 2 is the speaker device according to claim 1, characterized in that a plurality of the magnetic circuits are provided, and each magnetic circuit is connected to the ground terminal in an electrically connected state. The invention of claim 3 is the speaker device according to claim 1 or 2, characterized in that the overcurrent protection fuse is provided outside an enclosure that houses the magnetic circuit. Effect of the Invention

[0009] According to the speaker device of claim 1, even if the voice coil accidentally comes into contact with the plate of the magnetic circuit and a short circuit occurs, the protective fuse inserted in the earth line of the magnetic circuit melts due to an overcurrent, preventing the overcurrent from flowing out of the magnetic circuit, thereby avoiding the risk of smoke or fire due to an overcurrent. According to the speaker device of claim 2, even if a plurality of magnetic circuits are provided, the risk of smoke or fire due to an overcurrent can be avoided. According to the speaker device of claim 3, a blown protective fuse can be easily replaced. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a structure of a speaker device according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

[0012] FIG. 1 is a cross-sectional view showing the structure of the speaker device of the present invention. A conductor is wound around a cylinder supported by an annular damper 9 to form a voice coil 1. An audio signal current for generating an electromagnetic force according to Fleming's left-hand rule is input to the voice coil 1 from an audio output electric circuit (not shown). The pole yoke 2 is made of a soft magnetic material, and has a cylindrical pole part extending to the position (height) where the voice coil 1 is placed, disposed approximately at the center, and a cylindrical flange part is provided at the lower end. The magnet 3, which is a permanent magnet formed in an annular shape, is provided overlapping the upper surface of the flange part of the pole yoke 2. The plate 4 is an annular member made of a soft magnetic material, and is provided overlapping the upper surface of the magnet 3 with the pole part of the pole yoke 2 inserted in the center.

[0013] The pole yoke 2 and plate 4 sandwich the permanent magnet 3 from above and below, so that each is excited to a different magnetic pole. As a result, a strong magnetic field is generated in the gap between the pole part of the pole yoke 2, into which the voice coil 1 is inserted, and the plate 4. A magnetic circuit is a structure for generating a strong magnetic field in this kind of gap.

[0014] The diaphragm 6 is a member made of paper or the like and formed into a cone shape whose diameter gradually increases toward the top. The diaphragm 6 is connected at its small diameter portion to a cylinder (hereinafter abbreviated as "bobbin") on which the voice coil 1 is mounted. When an electromagnetic force acts on the voice coil 1 according to Fleming's left-hand rule and it moves in the up-down direction in FIG. 1, the movement of the voice coil 1 is transmitted to the diaphragm 6, causing the diaphragm 6 itself to vibrate. The vibration of the diaphragm 6 causes the air to vibrate, generating sound waves (sound).

[0015] The damper 9, which supports the cylinder (bobbin) on which the voice coil 1 is mounted, is formed in an annular shape and has multiple concentric wavy shapes. By supporting the bobbin on a concentric circle in this manner, the movement of the bobbin due to electromagnetic force is restricted to the vertical direction of the gap between the pole part of the pole yoke 2 and the plate 4.

[0016] The frame 5 is fixed to the upper surface of the plate 4 that constitutes the magnetic circuit by using screws. In addition, the outermost periphery of the annular damper 9 that supports the bobbin is fixed to the frame 5 by using an adhesive or the like. With this configuration, the voice coil 1 of the bobbin can move up and down in the gap between the pole part of the pole yoke 2 and the plate 4 without coming into contact with the plate 4. In other words, the voice coil 1 and the magnetic circuit including the plate 4 are electrically separated.

[0017] Edge 7, which is annular and formed so that its radial cross section is approximately Ω-shaped, is a member for supporting the outermost peripheral edge of diaphragm 6 to frame 5. Edge 7 may be formed of the same material as diaphragm 6 and integrated with diaphragm 6, or may be formed of a different material and bonded to diaphragm 6 with adhesive or the like. This edge 7 not only supports diaphragm 6 to frame 5, but also functions to absorb unnecessary vibrations generated by diaphragm 6. Gasket 8 is a member for finally supporting edge 7 attached to diaphragm 6 to frame 5.

[0018] The configurations according to the embodiments of the present invention described above are substantially the same as those of a conventional speaker device to which the present invention is not applied, and therefore a description of the operation of the speaker device having these configurations will be omitted.

[0019] Next, differences between the speaker device according to the present invention and a conventional speaker device, that is, characteristic configurations according to the present invention, will be described.

[0020] If frame 5 is made of metal (a diamagnetic material such as aluminum or copper), fixing plate 4, which is part of the magnetic circuit, to frame 5 with metal screws will electrically connect the magnetic circuit to frame 5. "Electrically connecting" A and B means being able to pass electricity between A and B, and includes not only connecting A and B with, for example, a copper lead wire (conductor), but also joining A and B by welding a conductive member or joining them by crimping a conductive member with a screw member.

[0021] Since the magnetic circuit earth terminal 12 is attached to the frame 5, as shown in Fig. 1, if one of the lead wires 11 extending from both ends of the overcurrent blowout protection fuse 10 is attached to the magnetic circuit earth terminal 12 and the other end of the lead wire 11 is grounded via the earth connection terminal 13, the potential of the magnetic circuit will be the so-called earth potential. Therefore, according to this device, the potential of the magnetic circuit is stabilized, and high quality of the reproduced sound is realized.

[0022] An overcurrent blowout protection fuse 10 (hereinafter simply referred to as "protection fuse 10") is inserted in the so-called earth circuit that is connected to frame 5 and grounded, so that even if an audio signal current larger than expected flows through voice coil 1, causing voice coil 1 to come into contact with a magnetic circuit such as plate 4, and an overcurrent flows from voice coil 1 to the ground via the magnetic circuit, the protection fuse 10 will blow due to an overcurrent that exceeds a preset standard, and the blowout will cut off the overcurrent flow to the ground. This makes it possible to prevent dangerous situations such as smoke or fire caused by heating due to an overcurrent in voice coil 1 or the magnetic circuit.

[0023] When the frame 5 is made of resin, it is difficult to electrically couple the magnetic circuit and the frame, so for example, a copper wire may be attached to the flange portion or plate 4 of the pole yoke 2 that constitutes the magnetic circuit, and the copper wire may be connected to a lead wire 11 extending from the protective fuse 10 for grounding. In this case, if the copper wire drawn out from the magnetic circuit is connected to a metallic magnetic circuit earth terminal 13 attached to the resin frame 5, the magnetic circuit is grounded via the protective fuse 10, as in the case of the metal frame described above, so that the potential of the magnetic circuit can be stabilized and at the same time the occurrence of smoke and fire accidents can be prevented.

[0024] Some speaker devices are equipped with multiple speaker units, such as a treble speaker unit and a bass speaker unit. In the case of such a speaker device, multiple magnetic circuits are provided corresponding to each speaker unit. In order to apply the present invention to a speaker device equipped with multiple magnetic circuits, the multiple magnetic circuits are electrically connected to each other to form one virtual magnetic circuit, and one magnetic circuit earth terminal is provided for the one virtual magnetic circuit. Then, the other lead wire of the overcurrent blowout protection fuse, one of whose lead wires is connected to an earth connection terminal, is connected to this magnetic circuit earth terminal, and the earth connection terminal is grounded. In this way, the potentials of the multiple magnetic circuits are all stabilized to the reference potential (earth potential), and the output sound of each of the multiple speaker units is also of high quality. Even if unexpected contact occurs between the voice coil and the magnetic circuit in any of the speaker units, the overcurrent flowing from the voice coil to the contact magnetic circuit causes the overcurrent blowout protection fuse to blow, blocking the flow of the overcurrent to the ground point, thereby preventing the occurrence of smoke and fire accidents.

[0025] If multiple speaker units are all provided with a magnetic circuit earth terminal on the conductive frame as shown in Figure 1, then the respective magnetic circuit earth terminals can be connected, for example with a copper wire, and then one of the magnetic circuit earth terminals can be connected to the lead wire of an overcurrent fuse whose other lead wire is connected to the earth connection terminal, and the earth connection terminal can be grounded.

[0026] If the frames of multiple speaker units are made of plastic, then the multiple magnetic circuits can be connected together with copper wire or the like, and then the copper wire can be connected to a (metal) magnetic circuit earth terminal attached to the plastic frame, for example. Then, the other lead wire of an overcurrent protection fuse, whose earth connection terminal is attached to a lead wire, can be connected to the magnetic circuit earth terminal, and the earth connection terminal can be grounded.

[0027] Usually, a speaker device is constructed by storing components such as a frame 5 supporting a diaphragm 6 and a magnetic circuit including a pole yoke 2 in a storage box called an enclosure. Therefore, if the protective fuse 10 is placed near components inside the enclosure such as the frame 5, the enclosure must be disassembled to replace the protective fuse 10 when it melts, and the replacement work is not efficient. For this reason, for example, a lead wire previously connected to a magnetic circuit earth terminal 12 attached to the frame 5 is pulled out to the outside of the enclosure and connected to a fuse connection terminal (not shown). One end of the protective fuse 10 is connected to the fuse connection terminal, and the other end is connected to the earth connection terminal 13 for grounding. Therefore, in order to prevent the occurrence of an accident, even if the protective fuse 10 melts, not only is the melted state easily visible outside the enclosure, but the protective fuse 10 can also be easily replaced.

[0028] It is not necessary for the protective fuse to be completely attached to the outside of the enclosure, and for example, the location on the enclosure where the protective fuse is attached may be covered with transparent resin or the like. Alternatively, the portion of the enclosure where the protective fuse lead wire pull-out hole is drilled may be processed into a recessed shape to accommodate the protective fuse, and a lid made of transparent resin or the like may be provided to cover the recessed portion. In other words, it is sufficient that the protective fuse is attached in a state where it is not necessary to remove the enclosure when replacing the protective fuse. [Explanation of symbols]

[0029] 1: Voice coil 2: Paul York 3: Magnet 4: Plate 5: Frame 6: Vibration plate 7: Edge 8: Gasket 9: Damper 10: Overcurrent protection fuse 11: Overcurrent protection fuse lead wire 12: Magnetic circuit earth terminal 13: Earth connection terminal

Claims

1. a ground terminal electrically connected to a magnetic circuit including the yoke, the magnet, and the plate; The speaker device is characterized in that one end of an overcurrent protection fuse is electrically connected to the earth terminal, and the other end of the overcurrent protection fuse is electrically grounded.

2. 2. The speaker device according to claim 1, wherein a plurality of the magnetic circuits are provided, and each magnetic circuit is electrically connected to the ground terminal.

3. 3. The speaker device according to claim 1, wherein the overcurrent protection fuse is provided outside an enclosure that houses the magnetic circuit.

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