JP2737273B2 - Electrodynamic speaker - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodynamic loudspeaker that eliminates a decrease in sound pressure due to an increase in impedance in a high frequency range due to an inductance of a voice coil and increases an output sound pressure in a high frequency range. Things.

2. Description of the Related Art In recent years, with the digitalization of audio equipment, high-quality sources (CD, DAT, etc.) over the entire audio band have been put into practical use. In particular, the decrease of the output sound pressure accompanying the rise of the voice coil impedance in the high frequency range is remarkable and inevitable. Conventionally, as a method of reducing the decrease in output sound pressure due to the rise in voice coil impedance, a method of coupling a copper ring to the top plate on the center pole surface at the position where the opposing magnetic pole is formed is often used. The pressure-frequency characteristic has a small decrease in sound pressure in a high frequency range because the rise in impedance is small.

Hereinafter, the above-described conventional copper ring type electrodynamic speaker will be described with reference to the drawings.

FIG. 7 is a cross-sectional view of a conventional copper ring type electrodynamic speaker. In FIG. 7, a magnetic circuit 1 is configured by arranging a ring-shaped magnet 4 and a top plate 5 on a bottom plate 3 having a center pole 2.
In addition, a frame 6 is connected, a peripheral portion of the diaphragm 8 is connected to a peripheral portion of the frame 6 together with a gasket 7, and a voice coil 9 is connected to a central portion of the diaphragm 8. In the electrodynamic loudspeaker, the voice coil 9 is fitted in the magnetic gap 11 of the magnetic circuit 1 without eccentricity, and the dust cap 12 is fixed to the center surface of the diaphragm 8. A copper ring 13 formed by shaping a copper plate into the shape shown in FIG. 9 is joined to the surface of the center pole 2 at a position where the top plate 5 and the opposing magnetic pole are formed. In the electrodynamic loudspeaker having such a configuration, the copper ring 13 functions as a short ring to short-circuit the eddy current generated in the center pole 2, thereby reducing an increase in voice coil impedance in a high frequency range. The decrease in pressure is reduced.

Problems to be Solved by the Invention However, the above-mentioned electrodynamic loudspeaker with a copper ring has the following problems. Voice coil 9
In order to ensure the reliability (that the voice coil 9 does not rub or hit the center pole 2 or the top plate 5) at the time of the large vibration, the magnetic field formed from the inside of the voice coil 9 and the center pole 2 The limit value of the gap length 11a is inevitably larger than that of the electrodynamic speaker without the copper ring 13. As a result, the magnetic gap 11 is increased, and the electrodynamic loudspeaker with the copper ring has a smaller magnetic flux density limit value than the electrodynamic loudspeaker without the copper ring 13, and the overall sound pressure level is reduced. . Therefore, in order to prevent the sound pressure frequency from lowering in the electrodynamic loudspeaker with a copper ring, one having a larger magnetomotive force must be used as compared with the magnet of the electrodynamic loudspeaker without the copper ring. In consideration of the reliability of the voice coil 9 at the time of large amplitude, this type of type is used when it is desired to increase only the high-range sound pressure level of the electrodynamic loudspeaker in which the magnetic circuit 1 is optimally designed to obtain effective magnetic energy. In the case of an electrodynamic speaker with a copper ring, the same magnet size causes a large change in sound quality in the middle and low frequencies due to a decrease in sound pressure, and the magnet size increases to achieve the same sound pressure level, resulting in poor cost performance. There is a problem that.

The dotted line in FIG. 8 shows the output sound pressure frequency characteristic and the impedance characteristic of the electrodynamic loudspeaker of which the magnetic gap length cannot be reduced any more, and the solid line shows the electrodynamic loudspeaker with the copper ring.

The present invention solves the above-mentioned problems. The gap length cannot be reduced any more. With the same gap length as that of the conventional electrodynamic speaker, the rise of the voice coil impedance in the high frequency range is eliminated, and the output sound pressure in the high frequency range is reduced. It is intended to realize an electrodynamic loudspeaker capable of raising only the level.

Means for Solving the Problems In order to solve the above problems, an electrodynamic loudspeaker according to the present invention has a ring shape having the same diameter as the center pole on the upper end face of the center pole and a top formed with opposed magnetic poles. Forming a copper plate on a cylinder with a width equivalent to the wire length protruding upward from the top plate upper end of the top plate of a voice coil wire with a winding width larger than the plate width A magnetic circuit in which the copper cap is joined to a position parallel to a wire loop protruding upward from the upper end of the top plate. Furthermore, as a means to eliminate the rise of high-frequency voice coil impedance,
In the center pole forming the opposing magnetic pole with the top plate of the magnetic circuit, a wire coil projecting downward from the lower end of the top plate of the voice coil wire having a winding width larger than the width of the top plate downward from the lower end position of the top plate. A groove having a width equal to the length and having a width equal to the wire length protruding downward from the lower end of the top plate of the voice coil wire having a larger winding width than the top plate width. A copper plate having an equivalent thickness is wound around the groove one round.

Operation With this configuration, the present invention short-circuits the eddy current flowing on the center pole by the voice current flowing through the voice coil, thereby reducing the output sound pressure and reducing reliability without increasing the magnetic gap length, that is, reducing the magnetic flux density. , The increase in impedance due to the high-frequency inductance of the voice coil can be reduced, and the high-frequency output sound pressure level can be increased.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of an electrodynamic speaker according to the present invention. In FIG. 1, a frame 26 is connected to a magnetic circuit 21 in which a ring-shaped magnet 24 and a top plate 25 are disposed on a bottom plate 23 having a center pole 22, and a diaphragm together with a gasket 27 is provided on a peripheral portion of the frame 26. 28
The voice coil 29 is connected to the center of the diaphragm 28, and the middle part of the voice coil 29 is damped.
In the electrodynamic loudspeaker, which is held by the voice coil 29 without eccentricity in the magnetic gap 31 of the magnetic circuit 21 and is fixed to the dust cap 32 on the central surface of the diaphragm 28, the center pole The upper end surface of the center pole 22 has a ring shape having the same diameter as the center pole 22 and projects upward from the upper end of the top plate 25 of the voice coil wire having a winding width larger than the width of the top plate 25 forming the opposed magnetic pole. It has a structure in which a copper cap 33 formed by molding a copper plate having a width equivalent to the wire loop length into a cylindrical shape is joined to a position parallel to a wire loop protruding upward from the upper end of the top plate 25.
The operation of the electrodynamic loudspeaker configured as described above will be described below.

The eddy current flows through the center pole 22 by the current flowing through the voice coil 29 having a larger winding width than the width of the top plate 25 that is fitted without eccentricity into the magnetic gap 31 of the magnetic circuit 21, and the eddy current flows above the top plate 25, The eddy current is short-circuited by the copper ring 33 arranged in parallel with the protruding voice coil 29, the voice coil impedance in the high frequency band is reduced, and the high frequency output sound pressure level is increased. FIG. 2 is a perspective view of the copper ring 33. The solid line in FIG. 3 shows the sound pressure frequency characteristic and the impedance characteristic of the electrodynamic loudspeaker shown in the first embodiment, and the dotted line shows the electrodynamic loudspeaker without the copper ring 33.

As described above, according to the first embodiment, it is possible to increase only the output sound pressure level in the high frequency range by suppressing the increase in the voice coil impedance in the high frequency range without increasing the magnetic gap length. .

FIG. 4 shows a second embodiment of the electrodynamic loudspeaker of the present invention. The top plate of the voice coil wire loop whose winding width is larger than the top plate width is located below the lower end of the top plate 25 at the center pole 22 forming the opposing magnetic pole with the top plate 25 of the electrodynamic speaker shown in FIG. A groove 34 with a constant depth is formed at the same width as the wire length protruding downward from the lower end of 25, and from the lower end of the top plate 25 of the voice coil wire whose winding width is larger than the top plate width from the lower end to the lower part. It has a structure in which a copper plate 35 having a width equal to the length of the projecting wire loop and having a thickness equal to that of the groove 34 is wound around the groove 34 once. FIG. 5 shows a center pole in the second embodiment.
FIG. 2 is a perspective view of a bottom plate 23 having 22.

The operation of the electro-dynamic loudspeaker configured as described above will be described below.

An eddy current flows through the center pole 22 due to the current flowing through the voice coil 29 having a larger winding width than the width of the top plate 25, which is fitted without eccentricity into the magnetic gap 31 of the magnetic circuit 21, and the eddy current flows upward from the top plate 25. The eddy current is short-circuited by the copper ring 33 arranged in parallel with the projecting voice coil wire and the copper plate 35 arranged in parallel with the voice coil wire projecting below the top plate 25, and the voice coil inductance is reduced. The voice coil impedance at high frequencies decreases, and the high-frequency output sound pressure level increases.

The solid line in FIG. 6 shows the sound pressure frequency characteristic and the impedance characteristic of the electrodynamic loudspeaker shown in the second embodiment, and the dotted line shows the electrodynamic loudspeaker without the copper ring 33 and the copper plate 35. As described above, according to the second embodiment, only the output sound pressure level in the high frequency range can be increased by suppressing the increase in the voice coil impedance in the high frequency range without increasing the magnetic gap length. The second embodiment is different from the first embodiment in that the voice coil impedance in the higher frequency range is reduced and the high-frequency output sound pressure level is increased.

Effect of the Invention As described above, the present invention provides a top plate of a voice coil wire loop having a ring shape having the same diameter as the center pole on the upper end surface of the center pole and having a larger winding width than the top plate width forming the opposing magnetic pole. The magnetic gap length is reduced by a structure in which a copper gap formed by forming a copper plate having a width equivalent to the length of the wire loop protruding upward from the top into a cylindrical shape is joined to a position parallel to the wire loop protruding upward from the upper end of the top plate. Without increasing, that is, without decreasing the output sound pressure, an increase in the high-frequency voice coil impedance can be suppressed, and the sound quality design and the high-frequency sound pressure level can be easily increased. Further, in the center pole forming the opposing magnetic pole with the top plate in the above-mentioned electrodynamic speaker, from the lower end position of the top plate to the lower side,
A voice coil whose winding width is larger than the top plate width. A voice coil impedance in a higher frequency range due to a structure in which a copper plate having a width equal to the length of the wire protruding downward from the lower end of the top plate of the wire and having a thickness equivalent to the groove is wound around the groove one round. Can be suppressed, and the sound pressure level in the high range can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electrodynamic loudspeaker according to an embodiment of the present invention, FIG. 2 is a perspective view of the copper ring, and FIG. FIG. 4 is a diagram showing the output sound pressure frequency characteristics and impedance characteristics of an electrodynamic loudspeaker without a copper ring, FIG. 4 is a cross-sectional view of an electrodynamic loudspeaker in another embodiment, and FIG. 5 is a perspective view of a bottom plate having the center pole. FIG. 6 is a diagram showing output sound pressure frequency characteristics and impedance characteristics of an electrodynamic speaker and an electrodynamic speaker without a copper ring according to another embodiment of the present invention. FIG. FIG. 8 is a cross-sectional view of a conventional speaker, and FIG. 8 is a graph showing output sound pressure frequency characteristics and impedance characteristics of a conventional copper ring type electrodynamic speaker and a conventional electrodynamic speaker without a copper ring. FIG. 21 ... magnetic circuit, 22 ... center pole, 23 ... bottom plate, 24 ... magnet, 25 ... top plate,
26 …… Frame, 28 …… Diaphragm, 29 …… Voice coil,
31 ... magnetic gap, 33 ... copper ring.

Claims (2)

(57) [Claims] 1. An upper end face of a center pole of a magnetic circuit,
A ring-shaped copper plate having the same diameter as this center pole, and a copper plate having a width equal to the length of a wire loop protruding upward from the upper end of the top plate of the voice coil wire having a winding width larger than the width of the top plate forming the opposed magnetic pole. An electrodynamic loudspeaker in which a copper ring formed into a cylindrical shape is connected to a position parallel to a wire loop protruding upward from the top plate upper end. 2. A line projecting downward from a lower end of the top plate of a voice coil wire loop having a winding width larger than a width of the top plate, from a lower end position of the top plate to a center pole forming a facing magnetic pole with the top plate. A groove with a width equal to the ring length and a constant depth is formed, and has a width equivalent to the wire ring length protruding downward from the lower end of the top plate of the voice coil wire loop whose winding width is larger than the top plate width. The electrodynamic speaker according to claim 1, wherein a copper plate having a thickness equivalent to that of the groove is wound around the groove one round.