JP2008035260A - Speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent abnormal sound from occurring since a voice coil comes into contact with a center pole in a speaker. <P>SOLUTION: In the speaker 1 for detecting electrostatic capacity formed between the voice coil 4 and the center pole 5 for outputting as an electric signal, the portion of the center pole 5 that can come into contact with the voice coil 4 opposingly is coated with a non-conductive material 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a speaker. More specifically, the present invention relates to a speaker that detects a capacitance formed between a voice coil and a center pole and outputs it as an electric signal.

  As a technique for improving the sound quality of a speaker, a speaker equipped with an MFB (Motion Feed Back) circuit is known. This MFB circuit detects an operating state of a vibrating plate based on an electric signal (also referred to as a sound signal) indicating sound information input to a speaker, and feedback-controls the vibrating plate based on the detection result. In this way, it is possible to eliminate distortion of sound that is likely to occur particularly in the low sound range. Therefore, it is generally considered that the MFB circuit is effectively employed in a small speaker that is difficult to reproduce in a low sound range.

  In the MFB circuit, the operating state of the diaphragm is detected by detecting a change in capacitance formed between the electrodes. Specifically, an electrode (hereinafter referred to as a movable electrode) is fixed to a diaphragm or an electromagnetic coil called a voice coil for vibrating the diaphragm, and the electrode (hereinafter referred to as a movable electrode) is opposed to the movable electrode. The fixed capacitance is fixed, and the capacitance that is changed by moving the movable electrode relative to the fixed electrode is detected by the detector, and this is detected by the conversion circuit as an electrical signal (also called a detection signal). ) And output. Then, the detection signal and the audio signal are compared by a comparison device (for example, CPU), and the operation of the diaphragm is appropriately performed based on the comparison result, that is, the difference between the output level of the detection signal and the output level of the audio signal. Control.

  As a conventional speaker that detects a change in capacitance formed between a voice coil as an electrode and a center pole as described above, converts it into an electric signal, and outputs it, for example, as shown in FIG. Further, a magnetic circuit is formed by the magnet 105 and the yoke 104 with the columnar center pole 103, and the cylindrical voice coil 101 in which the coil 102 is wound in the annular gap 107 between the center pole 103 and the yoke 104. The voice coil 101 and the diaphragm 106 are connected to each other and supported by a frame (not shown) to vibrate the diaphragm 106 to generate sound (Patent Document 1).

JP 53-12320 A

  However, the speaker of Patent Document 1 has a problem that when the voice coil 101 as an electrode and the center pole 103 come into contact with each other, an abnormal signal is generated and an abnormal sound is generated. For this reason, it is difficult to say that a good sound generation state is ensured even when the speaker itself vibrates or there is an abnormal input, for example.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a speaker that can prevent abnormal noise that occurs when a voice coil and a center pole come into contact with each other.

  In order to achieve such an object, a speaker according to the present invention is a speaker that detects an electrostatic capacitance formed between a voice coil and a center pole and outputs it as an electric signal, and at least one of the voice coil and the center pole. At least a portion where the voice coil and the center pole can come into contact with each other is coated with a non-conductive material.

  Therefore, according to this speaker, since the portion where at least one of the voice coil and the center pole can come into contact with the center pole is coated with a non-conductive material, the voice coil and the center pole are in contact with each other. Even so, the two are not electrically connected and a short circuit is prevented.

  According to the speaker of the present invention, even if the voice coil and the center pole are in contact with each other, the two are not electrically connected and a short circuit is prevented. Since no abnormal sound is generated, for example, even if the speaker itself vibrates or there is an abnormal input, a good sound generation state can be ensured.

  Hereinafter, the configuration of the present invention will be described in detail based on the best mode shown in the drawings.

  1 and 2 show an example of an embodiment of a speaker of the present invention. The speaker 1 detects a capacitance formed between the voice coil 4 and the center pole 5 and outputs it as an electric signal, and a portion of the center pole 5 which can be opposed to the voice coil 4 Is coated with a non-conductive material 6.

  The speaker 1 includes a damper 2, a diaphragm 3, a voice coil 4, a center pole 5, a magnet 7, a yoke plate 8, and a yoke case 9.

  The yoke case 9 is formed in a bowl shape with a circular cross section.

  The yoke plate 8 is formed in a disk shape having a through hole 8a at the center. Further, the yoke plate 8 is formed so that the diameter is at least larger than the diameter of the opening of the yoke case 9. The yoke plate 8 is fixed to the end surface on the opening side of the yoke case 9 with the through hole 8a positioned substantially at the center of the opening of the yoke case 9.

  The magnet 7 is formed in a disk shape with a constant thickness. Then, one surface of the disk-shaped magnet 7 and the inner bottom surface 9a of the yoke case 9 are bonded together, and the magnet 7 is fixed to substantially the center of the inner bottom surface 9a.

  The center pole 5 is made of iron, has a cylindrical center pole body 5a, a belt-like protrusion 5b formed around the center pole body 5a around the outer periphery of the center pole body 5a, and a base of the center pole body 5a. It is comprised from the flange 5c formed in the end. Then, the end surface of the center pole 5 on the flange 5c side and the magnet 7 fixed to the inner bottom surface 9a of the yoke case 9 are bonded, and the axial center of the cylindrical center pole body 5a is substantially perpendicular to the inner bottom surface 9a. The center pole 5 is fixed in a state in which it is positioned substantially at the center of the inner bottom surface 9a.

  As shown in FIG. 2, the outer peripheral surface of the belt-like protrusion 5 b of the center pole 5 is coated with a non-conductive material 6. The non-conductive material 6 has only to be insulating and can be thinly coated. Specifically, for example, a fluororesin is coated with a thickness of the order of microns.

  In the state where the end surface on the flange 5c side, which is the base end side, is bonded to the magnet 7, the center pole 5 substantially coincides with the position of the belt-like protrusion 5b and the through hole 8a of the yoke plate 8, and the center pole body The tip portion of 5a is formed and disposed so as to protrude from the through hole 8a to the outside of the yoke case 9.

  The center pole 5 and the yoke case 9 are connected to a housing (not shown) called an enclosure, and are grounded.

  The voice coil 4 includes a cylindrical bobbin 4a having both ends opened, and a coil 4b wound around the outer periphery of the bobbin 4a in a strip shape.

  The bobbin 4a has an inner diameter slightly larger than the outer diameter of the band-shaped protrusion 5b of the center pole 5, that is, an air gap is formed between the inner peripheral surface of the bobbin 4a and the outer peripheral surface of the band-shaped protrusion 5b of the center pole 5. The inner diameter is adjusted so as to be formed. And it inserts in the inside of the yoke case 9 from the through-hole 8a of the yoke plate 8, covers at least the strip | belt-shaped projection part 5b, and covers the center pole main body 5a.

  The coil 4b is wound around the outer periphery of the bobbin 4a at a position facing the through hole 8a of the yoke plate 8 with the bobbin 4a covered on the center pole body 5a. As the coil 4b, specifically, a conductor such as an enameled wire or a conductive wire is used.

  The through hole 8a of the yoke plate 8 has an air gap between the outer peripheral surface of the coil 4b wound around the outer periphery of the bobbin 4a and the inner peripheral surface of the through hole 8a with the bobbin 4a covered on the center pole body 5a. The diameter is adjusted so that a gap is formed.

  The damper 2 and the diaphragm 3 are attached to the bobbin 4a of the voice coil 4. The damper 2 is a circular thin plate having a plurality of bent portions and a hole for penetrating the bobbin 4a at the center, and the edge of the center hole is joined to the outer peripheral surface of the bobbin 4a with an adhesive, and the outer peripheral edge portion. Is bonded to the frame 12 with an adhesive. The diaphragm 3 functions as a so-called cone paper and is formed in a mortar shape having a hole for allowing the bobbin 4a to pass through at the bottom, and the edge of the hole at the bottom is joined to the outer peripheral surface of the bobbin 4a with an adhesive. The outer peripheral edge is joined to the frame 12 via the joint 13. The damper 2 and the diaphragm 3 are formed of a flexible material, and the voice coil 4 is supported so as to be able to vibrate in the axial direction of the cylindrical bobbin 4a.

  The frame 12 is formed in a mortar shape having a hole for allowing the bobbin 4a to pass through substantially at the center of the bottom. Then, the bottom part is joined to the yoke plate 8 with an adhesive, and the outer peripheral edge part is joined to a housing called the enclosure with a screw or an adhesive, and grounded.

  The opening 4 c on the opposite side of the voice coil 4 from the yoke case 9 is covered with a center cap 14. The center cap 14 is made of aluminum or the like, and includes a main body portion 14a formed in a dome shape and a flange portion 14b formed along the outer peripheral edge of the main body portion 14a. The center cap 14 is fixed to the diaphragm 3 with the flange portion 14 b bonded to the diaphragm 3 with an adhesive.

  According to the speaker 1 configured as described above, an audio signal is input to the voice coil 4, that is, a current indicating the audio signal flows through the coil 4 b of the voice coil 4, and this current, the center pole 5, the magnet 7, The voice coil 4 vibrates in the axial direction of the cylindrical bobbin 4a by an excitation action by the magnetic flux formed between the yoke case 9 and the yoke plate 8. Accordingly, the damper 2 and the diaphragm 3 vibrate and sound is emitted from the speaker 1.

  And according to the speaker 1 of this invention, the outer peripheral surface of the strip | belt-shaped projection part 5b of the center pole 5 which may be in contact with the bobbin 4a inner peripheral surface of the voice coil 4 is provided with the insulating coating by the non-conductive material 6. Therefore, even if the voice coil 4 and the center pole 5 are in contact with each other, an abnormal signal is not generated by the contact between the two, and therefore the generation of abnormal sound is prevented.

  In addition, although the above-mentioned form is an example of the suitable form of this invention, it is not limited to this, A various deformation | transformation implementation is possible in the range which does not deviate from the summary of this invention. For example, in the present embodiment, the outer peripheral surface of the belt-like protrusion 5b, which is the portion of the center pole 5 facing the voice coil 4, is coated with the non-conductive material 6. However, the present invention is not limited to this. The part facing the center pole 5 may be coated with the non-conductive material 6, or the part facing both the center pole 5 and the voice coil 4 may be coated with the non-conductive material 6. Specifically, as shown in FIG. 3, a portion of the inner peripheral surface of the bobbin 4 a of the voice coil 4 that is opposed to the belt-like protrusion 5 b that is a portion that may come into contact with the belt-like protrusion 5 b of the center pole 5. May be coated with a non-conductive material 6 in a strip shape. At this time, since the voice coil 4 vibrates in the axial direction of the cylindrical bobbin 4a, the range in consideration of the maximum amplitude of the vibration of the voice coil 4 is coated with the non-conductive material 6 in a band shape. Also, as shown in FIG. 4, the portion of the inner peripheral surface of the bobbin 4a of the voice coil 4 that faces the band-shaped protrusion 5b of the center pole 5 is coated in a band shape with a non-conductive material 6 and the voice of the center pole 5 The outer peripheral surface of the belt-like protrusion 5b, which is a portion that can be opposed to the coil 4, may be coated with the non-conductive material 6.

  Furthermore, the present invention can be applied to a speaker having any configuration as long as it detects a capacitance formed between the voice coil and the center pole and outputs it as an electric signal. The configuration of the speaker of the invention is not limited to the configuration of the speaker 1 of the present embodiment.

It is a longitudinal cross-sectional view which shows an example of embodiment of the speaker of this invention. FIG. 2 is an enlarged vertical cross-sectional view of a portion where the center pole and the voice coil according to the embodiment of FIG. It is an enlarged vertical cross-sectional view of the coating part by a nonelectroconductive material which is an opposing part of the center pole of another embodiment, and a voice coil. FIG. 6 is an enlarged vertical cross-sectional view of a coating portion made of a non-conductive material, which is a portion facing a center pole and a voice coil according to still another embodiment. It is a longitudinal cross-sectional view which shows the conventional speaker.

Explanation of symbols

1 Speaker 4 Voice coil 5 Center pole 6 Non-conductive material

Claims (1)

In a speaker that detects an electrostatic capacitance formed between a voice coil and a center pole and outputs an electric signal, at least one of the voice coil and the center pole includes the voice coil and the center pole. A speaker characterized by coating a portion that can be opposed to contact with a non-conductive material.

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