JP3214816B2 - Speaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving coil type loudspeaker using a movable voice coil, and more particularly to a loudspeaker capable of reducing harmonic distortion of reproduced sound.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view showing a conventional moving coil type speaker used for a vehicle or the like.
The speaker shown in FIG. 4 is what is called a tweeter, and is mainly used for reproducing sound in a high frequency band. In the figure, reference numeral 21 denotes a dome-shaped diaphragm, the outer peripheral edge of which is elastically supported by a frame 23 described later via an elastic edge 22 having an arc-shaped cross section. A bobbin 24 formed of a non-magnetic material such as a paper material or a synthetic resin material into a cylindrical shape is connected to a lower portion of the outer periphery of the diaphragm 21. A voice coil 25 is wound around the outer periphery of the bobbin 24. Have been.

[0003] Inside the bobbin 24, a cylindrical inner yoke 2 made of a conductive material having a high magnetic permeability such as iron.
6 are arranged. A magnet 27 magnetized in the central axis direction (Y-axis direction) of the bobbin 24 is fixed to the lower end surface of the inner yoke 26, and the lower end surface of the magnet 27 is attached to the upper surface of an outer yoke 28 having a U-shaped cross section. It is fixed. The outer yoke 28 is also made of a conductive material having high magnetic permeability similarly to the inner yoke 26, and an annular portion 28a protruding upward in the figure is integrally formed at a peripheral edge thereof. A magnetic gap 29 is formed between the inner peripheral surface of the annular portion 28a and the outer peripheral surface of the inner yoke 26 for converging the DC magnetic flux from the magnet 27. The voice coil 25 is disposed in the magnetic gap 29. ing.

The frame 23 is formed in a substantially ring shape from a synthetic resin, and has an inner peripheral surface fitted and attached to an outer peripheral surface of the annular portion 28a of the outer yoke 28. A pair of input terminals 30, 30 to which a sound current is supplied from an external amplifier or the like are fixed to the frame 23. The input terminals 30, 30 and both ends of a conductor forming the voice coil 25 are electrically connected to each other. Lead wires 31, 31 for lateral connection extend laterally through between the upper surface of the frame 23 and the elastic edge 22. In the conventional speaker having the above-described configuration, an AC audio current is supplied to the voice coil 25 through the input terminals 30 and 30 and the lead wires 31 and 31, so that an electromagnetic force is applied to the voice coil 25 located in the magnetic gap 29. Working, this voice coil 2
The bobbin 24 and the diaphragm 21 vibrate in the Y-axis direction using the drive source 5 as a drive source.

[0005]

As described above, in the conventional speaker, the material of the inner yoke 26 and the outer yoke 28 for forming the magnetic gap 29 is as follows.
A conductive material such as iron having high magnetic permeability is used. Therefore, an eddy current is generated when the AC magnetic flux generated from the voice coil 25 when an audio current flows through the voice coil 25 passes through the inner yoke 26 and the outer yoke 28 located in the vicinity thereof. As a result, distortion occurs in the audio current flowing through the voice coil 25, and harmonic distortion appears in the reproduced sound. Also, due to the hysteresis loss associated with the non-linearity of the magnetic permeability of the inner yoke 26 and the outer yoke 28, harmonic components are generated in the audio current, which also causes harmonic distortion in the reproduced sound.

In particular, the inner yoke 26 located inside the voice coil 25 has a magnetic gap forming surface smaller in diameter and a smaller surface area than the magnetic gap forming surface of the outer yoke 28, so that the AC magnetic flux from the voice coil 25 is reduced. Magnetic flux density is increased, which is largely caused by eddy current and hysteresis loss. Needless to say, the harmonic distortion of the reproduced sound remarkably appears in the tweeter for reproducing the sound in the high frequency band. SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to reduce eddy current and hysteresis loss generated when power is supplied to a voice coil, and to reduce harmonic distortion of reproduced sound.

[0007]

In order to solve the above-mentioned problems, a speaker according to the present invention is provided with a bobbin formed of a non-magnetic material in a substantially cylindrical shape and connected to a diaphragm, and having an interval in the center axis direction of the bobbin. 2 that is wound around the outer peripheral surface of the bobbin
Two voice coils, two ring-shaped magnets that are radially magnetized and whose inner peripheral surface faces the outer periphery of each voice coil via a gap, and the outer peripheral surface of each magnet is fixed to the inner peripheral surface A cylindrical yoke that is not provided, and the yoke does not exist on the inner peripheral side of the bobbin. In the above, the inner peripheral surfaces of the two magnets facing the voice coil are magnetized so as to be different from each other at the N pole or the S pole, and the two voice coils are wound in opposite directions to be in the same direction when energized. Can be provided.

Further, a projection is provided on the inner peripheral side of the cylindrical yoke so as to project inward, and the two magnets are fitted to the inner peripheral surface of the cylindrical yoke so as to sandwich the projection. It is preferable to be mounted. further,
The outer peripheral surface of the cylindrical yoke may be fitted to the inner peripheral surface of a substantially cylindrical frame made of a non-magnetic material. In this case, a substantially annular protrusion is provided on the inner peripheral surface of the frame, the end of the cylindrical yoke is brought into contact with one end of the protrusion, and the other end of the protrusion is It is preferable that the outer peripheral edge of the elastic support body that supports the diaphragm so as to vibrate can be attached.

Further, a case having a step portion into which an end of the frame is fitted may be provided, and the cylindrical yoke may be held between the projecting portion of the frame and the step portion. Further, it is possible to provide an input terminal to which audio current is supplied in the case, and to arrange a lead wire for conducting the input terminal and the voice coil inside the bobbin.

According to the present invention, there are provided two magnets which are radially magnetized, and two voice coils which are directly opposed to the inner peripheral surface of the magnet, respectively, so as to reduce the total amount of magnetic flux passing through the voice coils. Since the yoke to be disposed inside the voice coil can be eliminated without using the voice coil, the occurrence of eddy current and hysteresis loss can be significantly reduced. In this case, the inner peripheral surfaces of the two magnets facing the voice coil are magnetized so as to be different from each other on the N pole or the S pole, and the two voice coils are wound in opposite directions, respectively, so that the two A driving force is applied to the voice coil in the same direction. The two voice coils may be formed by winding one conductor in the reverse direction from the middle, or may be formed separately by two conductors. In addition, the same effect can be obtained by winding two voice coils in the same direction and supplying voice currents in opposite directions to the respective voice coils.

[0011] Further, a protruding portion protruding inward is provided on the inner peripheral side of the cylindrical yoke, and two magnets are fitted on the inner peripheral surface of the cylindrical yoke so as to sandwich the protruding portion. Then, the positioning of the magnet can be easily performed, and the assembling workability is improved. The protruding portion is provided integrally with or separately from the cylindrical yoke, and is formed on the inner peripheral surface of the cylindrical yoke in an annular or dotted manner. Furthermore, if the outer peripheral surface of the cylindrical yoke is fitted on the inner peripheral surface of a substantially cylindrical frame made of a nonmagnetic material such as a synthetic resin, the assembling workability is further improved. In this case, an annular or circumferentially scattered protrusion is provided on the inner peripheral surface of the frame, and the end of the cylindrical yoke is brought into contact with one end surface of the protrusion to determine the position. Can be used as a mounting surface for mounting an outer peripheral edge of an elastic support member that supports the diaphragm so that the diaphragm can vibrate, thereby simplifying the structure.

Further, a step is provided in a case which covers the magnet or the voice coil on the side opposite to the diaphragm, an end of the frame is fitted into the step, and the step and the projection of the frame are connected to each other. If the cylindrical yoke is sandwiched and held therebetween, the assembling work is further simplified. Furthermore, since there is no yoke inside the bobbin, a lead wire for supplying a voice current to the voice coil can be connected to an input terminal provided at the center of the case through the space inside the bobbin. This facilitates the routing of the lead wire and makes it possible to reduce the outer diameter of the speaker.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a speaker according to the present invention. This speaker is called a tweeter, and is used to reproduce high frequency band audio. In the figure, reference numeral 1 denotes a dome-shaped diaphragm made of synthetic resin, paper, or a thin metal plate, and its outer peripheral portion is attached to an inner peripheral edge of an elastic edge (elastic support) 2 having an arc-shaped cross section. The elastic edge 2 is supported so as to be able to vibrate. An outer peripheral edge of the elastic edge 2 is bonded and fixed to an upper surface of an annular protrusion 3a of a frame 3 formed of a substantially cylindrical shape from a nonmagnetic material such as a synthetic resin. In this embodiment, the annular protrusion 3 a is formed integrally with the inner peripheral surface of the frame 3, but may be formed by fixing another ring-shaped member to the inner peripheral surface of the frame 3.

A bobbin 4 formed in a cylindrical shape from a non-magnetic material such as a paper material or a synthetic resin material is adhered and fixed to a lower portion of the outer peripheral edge of the diaphragm 1. Two voice coils 5, 6 are wound around the outer peripheral surface of the bobbin 4 with an interval in the direction of the center axis (Y axis) of the bobbin 4. The voice coils 5 and 6 are formed so that one conductor is wound in the opposite direction in the middle, so that the voice coils are wound in opposite directions. However, each of the voice coils 5 and 6 may be formed by two conductors, and then both voice coils may be electrically connected. Both ends of the conductor forming the voice coils 5 and 6 are drawn out to the lower end of the bobbin 4 and connected to the leads 7 and 7 by soldering, respectively.

The inner peripheral surfaces of the ring-shaped magnets 8, 9 are opposed to the outer peripheral side of each of the voice coils 5, 6 via minute magnetic gaps G, G, respectively. These magnets 8 and 9 are both radially magnetized, but are magnetized such that the inner peripheral surfaces thereof have different polarities. For example, the upper magnet 8 is magnetized with an N pole on the inner peripheral surface and an S pole on the outer peripheral surface, and the lower magnet 9 has an S pole on the inner peripheral surface and an N pole on the outer peripheral surface. Therefore, when a voice current flows through the above-mentioned oppositely wound voice coils 5, 6, an electromagnetic force in the same direction acts on the two voice coils 5, 6.

The outer peripheral surfaces of the magnets 8 and 9 are fitted and bonded to the inner peripheral surface of a cylindrical yoke 10 made of a highly magnetically permeable material. At the center of the inner peripheral surface of the cylindrical yoke 10 in the Y-axis direction, a positioning ring 11, which is an annular protrusion, is fixed. The positioning ring 11 is made of a non-magnetic material such as a synthetic resin. The upper and lower ends of the positioning ring 11 are in contact with the ends of the magnets 8 and 9 to determine the positions of the magnets 8 and 9 in the Y-axis direction. Have been. The positioning ring 11
May be formed integrally with the inner peripheral surface of the cylindrical yoke 10. The outer peripheral surface of the cylindrical yoke 10 is fitted on the inner peripheral surface of the frame 3, and the upper end surface in the figure is positioned in contact with the lower end surface of the annular projection 3a.

Reference numeral 12 in the drawing denotes a substantially disk-shaped case that covers the magnets 8, 9 and the bobbin 4 from below. The case 12 is made of a synthetic resin, and is integrally formed with an annular step 12a protruding upward near the outer peripheral edge. The frame 3 is provided on the outer peripheral surface of the step 12a.
The inner peripheral surface at the lower end is fitted and fixed. At this time,
The upper surface of the step portion 12a contacts the lower end surface of the cylindrical yoke 10, and the cylindrical yoke 10 is connected to the step portion 12a and the annular projection 3a.
And held between. Near the center of the case 12, input terminals 13, 13 to which audio current is supplied from an external amplifier or the like are fixed, respectively. The lead wires 7, 7 are fixed to the input terminals 13, 13 by soldering or the like, and the input terminals 13, 13 and the voice coils 5, 6 are conducted.

Next, the procedure for assembling the speaker of the present invention will be described. First, the magnets 8 and 9 are fitted and fixed to the inner peripheral surface of the cylindrical yoke 10 from above and below. At this time, if the magnets 8, 9 are inserted until they come into contact with the upper and lower end surfaces of the positioning ring 11, respectively, the height positions of the magnets 8, 9 are naturally determined, so that the radial direction of the magnets 8, 9 can be determined without using a jig. And positioning in the Y-axis direction. Next, the cylindrical yoke 10 to which the magnets 8 and 9 are fixed is fitted and fixed to the inner peripheral surface of the frame 3 from below in the figure. Also in this case, the upper end surface of the cylindrical yoke 10 is brought into contact with the lower surface of the annular projection 3a of the frame 3 so that positioning in the height direction can be performed, and no jig is required. Note that if the outer peripheral surface of the cylindrical yoke 10 is firmly fitted to the inner peripheral surface of the frame 3, it is not necessary to use an adhesive.

A vibration plate 1 has a bobbin 4 to which voice coils 5 and 6 and lead wires 7 and 7 are attached, and an elastic edge 2
And the diaphragm 1 is arranged on the upper surface side of the frame 3. At this time, since the lower end side of the frame 3 is largely opened, a jig for determining the center of the bobbin 4 can be easily attached and detached. And the center of bobbin 4 is Y
By fixing the outer peripheral edge of the elastic edge 2 to the upper surface of the annular projection 3a of the frame 3 in a state where the axis is aligned with
The diaphragm 1 is supported on the frame 3 so as to be able to vibrate. Next, with the free ends of the lead wires 7, 7 inserted through holes formed in the input terminals 13, 13, the input terminals 1
3 and 13 are fixed by soldering. Since the lead wires 7 need to follow the vibration of the bobbin 4 in the Y-axis direction,
It must be curved with some allowance. In the loudspeaker having the above configuration, since the yoke member does not exist inside the bobbin 4 and a wide space is formed, the lead wires 7 are formed using the area inside the bobbin 4 as shown in FIG. You can do it. Therefore, it is possible to reduce the outer diameter of the entire speaker.

After the above steps, the case 12 is moved to the step 1
The outer peripheral surface of 2a is fitted to the inner peripheral surface of the lower end of the frame 3 and is fixed by bonding. As a result, the lower surfaces of the diaphragm 1, the bobbin 4, and the magnets 8, 9 are covered, and intrusion of dust and the like is prevented. When the case 12 is attached, if the upper end surface of the step portion 12a is brought into contact with the lower end surface of the cylindrical yoke 10, the cylindrical yoke 10 is sandwiched between the step portion 12a and the annular projection 3a of the frame 3. The cylindrical yoke 10 is firmly held. As described above, since most of the components are fitted together and assembled, there is no need to pay attention to the centering of these components, and the assembly workability is extremely good. Further, since it is not necessary to manage the gap width between the inner peripheral surface of the bobbin 4 and the peripheral surface of the yoke to be disposed inside the bobbin 4, the assembling workability is also improved and the rejection rate is greatly reduced. .

The above-described speaker of the present invention has an input terminal 1
Voice currents in opposite directions are supplied to the voice coils 5 and 6 via the leads 3 and 13 and the leads 7 and 7 respectively. Since the inner peripheral surfaces of the two magnets 8 and 9 facing the voice coils 5 and 6 are magnetized with different polarities, an electromagnetic force in the same direction acts on the two voice coils 5 and 6, and The bobbin 4 and the diaphragm 1 vibrate in the Y-axis direction using the two voice coils 5 and 6 as driving sources.

The loudspeaker having the above structure is provided inside the bobbin 4,
That is, no yoke member for forming a magnetic flux loop is provided inside the voice coils 5 and 6, so that the magnetic flux becomes an open loop on the inner peripheral side of each of the magnets 8 and 9 and the magnetic flux density decreases. By adopting two magnets 8 and 9 and two voice coils 5 and 6 directly opposed to the inner peripheral surface which is a magnetic pole surface of the magnets 8 and 9, the amount of magnetic flux acting on the entire voice coils 5 and 6 Can be made substantially equal to the amount of magnetic flux acting on the voice coil 25 shown in FIG. 4, and a sufficient driving force can be obtained. Since no eddy current and no hysteresis loss particularly occur in the yoke members located inside the voice coils 5 and 6 when the voice coils 5 and 6 are energized, generation of harmonic components in the voice current is suppressed. It is possible to greatly reduce harmonic distortion of reproduced sound. It goes without saying that the weight and cost of the whole speaker can be reduced.

FIG. 2 is an output sound pressure characteristic diagram of the above-described speaker of the present invention, and FIG. 3 is an output sound pressure characteristic diagram of the conventional speaker shown in FIG. 4 for comparison. As apparent from these figures, according to the loudspeaker of the present invention, in the high frequency band of 1 kHz or more as compared with the conventional one, the harmonic 2
The third-order distortion and the third-order distortion are greatly reduced. Also, the sound pressure level has been greatly improved.

[0024]

According to the speaker of the present invention, since there is no yoke made of a conductive magnetic material for forming a magnetic circuit inside the voice coil, the eddy current due to the AC magnetic flux generated when the voice coil is energized is reduced. , The occurrence of hysteresis loss can be suppressed, and the harmonic distortion of the reproduced sound can be greatly reduced. Further, the size and weight of the entire speaker can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a speaker of the present invention.

FIG. 2 is an output sound pressure characteristic diagram of the speaker shown in FIG.

FIG. 3 is an output sound pressure characteristic diagram of a conventional speaker.

FIG. 4 is a sectional view showing a conventional speaker.

[Explanation of symbols]

1 diaphragm, 2 elastic edge (elastic support), 3
Frame, 3a annular protrusion, 4 bobbins, 5, 6
Voice coil, 7 lead wire, 8, 9 magnet,
Reference Signs List 10 cylindrical yoke, 11 positioning ring (projection), 12 case, 12a step, 13 input terminal, G magnetic gap

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hisayoshi Sugawara 1-1-1-8, Nishigotanda, Shinagawa-ku, Tokyo Examiner, Alpine Corporation Fukusaburo Matsuzawa (56) References JP-A-6-62492 (JP, A) JP-A-6-233380 (JP, A) JP-A 8-441 (JP, U) JP-A 64-51396 (JP, U) JP-A 57-143793 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04R 9/02 102 H04R 9/00

Claims (7)

(57) [Claims] 1. A bobbin formed of a non-magnetic material in a substantially cylindrical shape and connected to a diaphragm, and two voice coils wound around an outer peripheral surface of the bobbin at intervals in a center axis direction of the bobbin. And two ring-shaped magnets which are radially magnetized and whose inner peripheral surface is opposed to the outer periphery of each voice coil via an air gap, and a cylinder in which the outer peripheral surface of each magnet is fixed to the inner peripheral surface. And a yoke does not exist on the inner peripheral side of the bobbin. 2. An inner peripheral surface of the two magnets facing the voice coil is differently magnetized to an N pole or an S pole, respectively, and the two voice coils are respectively wound in opposite directions. 2. The speaker according to claim 1, wherein a driving force in the same direction is applied to the two voice coils when the power is supplied. 3. A protrusion protruding inwardly is provided on an inner peripheral side of the cylindrical yoke, and the two magnets are respectively provided on inner peripheral surfaces of the cylindrical yoke so as to sandwich the protrusion. The speaker according to claim 1, which is fitted. 4. The speaker according to claim 1, wherein the outer peripheral surface of the cylindrical yoke is fitted on the inner peripheral surface of a substantially cylindrical frame made of a non-magnetic material. 5. A substantially annular projection is provided on an inner peripheral surface of the frame, and an end of the cylindrical yoke abuts one end of the projection, and the other of the projections. The speaker according to claim 4, wherein a peripheral portion of an elastic support member that supports the diaphragm so as to vibrate is attached to an end surface of the speaker. 6. The case according to claim 5, wherein a case having a step portion into which an end of the frame is fitted is provided, and the cylindrical yoke is held between the projecting portion of the frame and the step portion. Speaker. 7. The case according to claim 6, wherein an input terminal to which an audio current is supplied is provided on the case, and a lead wire connecting the input terminal and the voice coil is arranged inside the bobbin. Speaker.