JPH1051887A - Speaker system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the sensitivity of the speaker, to increase an output sound pressure level, to reduce distortion and to increase a permissible input. SOLUTION: A primary coil 1 being a drive coil with a winding width L extended toward a front side and a back side of the speaker from a thickness P of a plate 22 is fixed in an air gap 23 of a magnetic circuit 20 where the air gap 23 is provided between a center pole 12 and the plate 22. The center pole 12 has a magnetic substance part toward the front side and the back side of the speaker in excess of the winding width L of the primary coil 1 respectively and has an outer circumferential face directed to a rear side or an oblique rear side of the speaker and an outer circumferential face directed to a front side or an oblique front side of the speaker. A secondary coil 2 making up of a short-circuit coil is placed in the air gap 23 while being fixed to a cone 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker device for sound reproduction.

[0002]

2. Description of the Related Art Various types of speakers for sound reproduction have been considered and put to practical use.

For example, a magnetic circuit having a gap between a center pole portion of a center pole yoke and a plate is formed by sandwiching a magnet between a center pole yoke and a plate, and a center pole is formed in the gap of the magnetic circuit. A primary coil, which is a driving coil, is fixed to a part or a plate, and a speaker unit in which a secondary coil constituting a short coil is arranged in a gap of a magnetic circuit by being fixed to a diaphragm so as to be opposed to the primary coil. It has been put to practical use as a coupled (electromagnetic induction type) speaker.

In this electromagnetically coupled speaker, a secondary current is induced in a secondary coil constituting a short coil by a signal current flowing through a primary coil which is a driving coil, and is interacted with a magnetic flux generated in a gap of a magnetic circuit. According to Fleming's left-hand rule, a driving force corresponding to the secondary current is generated in the secondary coil, and the diaphragm to which the secondary coil is fixed is displaced.

[0005] This electromagnetically coupled speaker has advantages in that the primary coil through which a signal current flows is fixed to a center pole or plate made of a magnetic material such as iron, so that it has excellent heat dissipation and can withstand a large input. If the secondary coil constituting the short coil is formed of a one-turn pipe or cylinder made of a non-magnetic conductive material, for example, aluminum, distortion can be reduced.

On the other hand, a dynamic speaker in which a voice coil bobbin is fixed to a diaphragm in a gap of a magnetic circuit and a voice coil serving as a driving coil is wound around the voice coil bobbin has been put to practical use.

[0007]

Conventionally, in an electromagnetically coupled speaker and a dynamic speaker, the drive coil has a winding width equivalent to the thickness of the plate forming the magnetic circuit, and the thickness of the plate in the front-back direction of the speaker is generally large. It is arranged in a position.

FIG. 19 shows an example of a conventional electromagnetically coupled speaker, in which a recess 13 is formed around the tip of a center pole section 12 of a center pole yoke 11.
The primary coil 1 as a drive coil is fitted into the recess 13 and attached to the center pole portion 12.

An opening (hole) 15 is formed in the flange portion 14 of the center pole yoke 11 at a position continuously adjacent to the center pole portion 12.
A terminal plate 16 is attached to the rear surface of the fourth terminal 4. And
A coil lead wire 17 made of, for example, a kinshi wire of the primary coil 1
Is adhered to the peripheral surface of the center pole portion 12 to form an opening 15
And is connected to the input terminal 18 on the terminal board 16 by soldering.

A magnet 21 is adhered to the front surface of the flange portion 14 of the center pole yoke 11, and a plate 22 is adhered to the front surface of the magnet 21. A magnetic circuit 20 having an air gap 23 between the magnetic circuit 20 and the inner peripheral surface is formed.

The secondary coil 2 constituting a short coil is inserted into the gap 23 of the magnetic circuit 20. The secondary coil 2 is a one-turn pipe or cylinder made of a nonmagnetic conductive material, for example, aluminum.

An inner peripheral portion of a cone 32 having an edge 31 on the outer peripheral portion, a center cap 33, and an inner peripheral portion of a damper 34 are attached to the secondary coil 2. Also,
A speaker frame 35 is attached to the plate 22, and the outer edge 31 of the cone 32 and the gasket 36 are attached to the speaker frame 35, and the outer periphery of the damper 34 is attached to the speaker frame 35.
Attached to.

[0013] As shown in the figure, the primary coil 1 serving as a driving coil has a winding width equivalent to the thickness of the plate 22 and is disposed at the position of the thickness of the plate 22 in the front-rear direction of the speaker.

However, in this configuration, the range of the uniform magnetic field distribution in the air gap 23 of the magnetic circuit 20 is limited by the solid line 8 in FIG.
As shown by, the magnetic energy in the gap 23 of the magnetic circuit 20 is not sufficiently utilized because the magnetic energy is limited to a range narrower than the position of the thickness P of the plate 22, and the sensitivity of the speaker decreases,
Output sound pressure level decreases.

Therefore, conventionally, by increasing the size of the magnet 21, the magnetic energy generated in the gap 23 of the magnetic circuit 20 is increased to increase the sensitivity of the speaker and to increase the output sound pressure level. However, this has the disadvantage that the cost of the speaker is increased.

Therefore, the present invention is to improve the sensitivity of the loudspeaker and to increase the output sound pressure level by efficiently utilizing the magnetic energy in the gap of the magnetic circuit. .

[0017]

According to the present invention, a speaker device is formed by a center pole yoke, a plate, and a magnet, and has a gap between the center pole portion of the center pole yoke and the plate. A magnetic circuit, and in the gap of the magnetic circuit,
A drive coil having a winding width extending from the position of the thickness of the plate to the front side and the rear side of the speaker is disposed, and the center pole portion is located on the front side and the rear side of the speaker from the position of the winding width of the drive coil. Each of them has a magnetic portion and has an outer peripheral surface facing rearward or obliquely rearward of the speaker and an outer peripheral surface facing forward or obliquely forward of the speaker.

In this case, in the speaker device, the drive coil may be a primary coil fixed between the respective magnetic portions of the center pole portion, and the driving coil may be fixed to a diaphragm in the gap. And an electromagnetically coupled speaker in which a secondary coil constituting a short coil is disposed.

Further, the speaker device can be a dynamic speaker in which the drive coil is fixed to a diaphragm and is a voice coil disposed in the gap.

In the loudspeaker device of the present invention configured as described above, in the gap of the magnetic circuit, between the plate and the outer peripheral surface of the center pole portion facing rearward or obliquely rearward of the speaker, and the center pole. A magnetic flux is also generated between the plate and the outer peripheral surface facing the front or obliquely forward of the speaker of the portion, and the range of the uniform magnetic field distribution in the gap of the magnetic circuit is shifted forward of the speaker from the position of the thickness of the plate. Spread side and back.

The driving coil has a winding width extending from the position of the thickness of the plate to the front side and the rear side of the speaker, and is located in the widened and uniform magnetic field distribution range. The magnetic energy in the section will be used efficiently. Therefore, the sensitivity of the speaker is improved, and the output sound pressure level is increased.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a speaker device according to the present invention, which is a case of a speaker unit of an electromagnetically coupled speaker. In the speaker unit 10 of this example, a concave portion 13 is formed around the tip of the center pole portion 12 of the center pole yoke 11, and the primary coil 1 as a drive coil is fitted into the concave portion 13 so that the center pole portion 12 is formed. Attached to.

As shown in FIG. 2, for example, the primary coil 1 is wound as an air-core coil, and is press-fitted into a recess 13 so as to be attached to the center pole portion 12. In this case, a magnetic ring 12a is press-fitted and bonded to the tip of the center pole portion 12 into which the primary coil 1 is fitted, and the winding width L of the primary coil 1 is the height of the recess 13 (the length in the front-rear direction of the speaker). C) The width R of the magnetic ring 12a is subtracted from C.

Alternatively, as shown in FIG. 3, the primary coil 1 is wound around a magnetic bobbin 12A having upper and lower flange portions 12c and 12e, and the magnetic bobbin 12A is pressed into the concave portion 13 of the center pole portion 12. By being bonded, the primary coil 1 is attached to the center pole portion 12. In this case, the winding width L of the primary coil 1 is an interval between the flange portions 12c and 12e of the magnetic bobbin 12A.

Alternatively, as shown in FIG. 4, the flange portion 12 is located above (in front of) the recess 13 of the center pole portion 12.
g is formed, and the primary coil 1 is directly wound around the concave portion 13 so that the primary coil 1 is attached to the center pole portion 12. In this case, the winding width L of the primary coil 1 is equal to the height of the recess 13.

As shown in FIG. 1, an opening (hole) 15 is formed in the flange portion 14 of the center pole yoke 11 at a position adjacent to and adjacent to the center pole portion 12. Has a terminal plate 16 attached thereto. Then, a coil lead wire 17 made of, for example, a tinsel wire of the primary coil 1 is adhered to the peripheral surface of the center pole portion 12, inserted into the opening 15, and connected to the input terminal 18 on the terminal plate 16 by soldering.

The coil lead wires 17 are provided at the beginning and end of winding of the primary coil 1, respectively, and each is connected to a separate input terminal. When the primary coil 1 is composed of a plurality of coils as will be described later, the coil lead wires 17 of the respective coils are adhered to the peripheral surface of the center pole portion 12 and inserted into the openings 15, and the terminal plate 16 is connected to an input terminal 18.

A magnet 21 is adhered to the front surface of the flange portion 14 of the center pole yoke 11, and a plate 22 is adhered to the front surface of the magnet 21. A magnetic circuit 20 having an air gap 23 between the magnetic circuit 20 and the inner peripheral surface is formed.

The secondary coil 2 constituting a short coil is inserted into the gap 23 of the magnetic circuit 20. The secondary coil 2 is a one-turn pipe or cylinder made of a non-magnetic conductive material, for example, aluminum, so that a bobbin around which the secondary coil 2 is wound can be omitted.

The inner peripheral portion of the cone 32 having the edge 31 on the outer peripheral portion, the center cap 33, and the inner peripheral portion of the damper 34 are attached to the secondary coil 2. Also,
A speaker frame 35 is attached to the plate 22, and the outer edge 31 of the cone 32 and the gasket 36 are attached to the speaker frame 35, and the outer periphery of the damper 34 is attached to the speaker frame 35.
Attached to.

Then, as shown in FIG. 2, FIG. 3 or FIG.
The winding width L of the primary coil 1 which is a drive coil is made larger than the thickness P of the plate 22, and as shown in FIG. It is considered extended.

Further, as shown in FIG. 5, the center pole portion 12 is formed of the magnetic ring 12a shown in FIG. 2, the flange portion 12c of the magnetic bobbin 12A shown in FIG. 3, or the center pole shown in FIG. Flange part 12g of part 12
Accordingly, a magnetic body portion 12C is provided at a position on the front side of the position of the winding width L of the primary coil 1, and a lower (rear side) portion of the concave portion 13 of the center pole portion 12 shown in FIG. The winding width L of the primary coil 1 is determined by the flange portion 12e of the magnetic bobbin 12A shown or the lower portion (rear side) of the concave portion 13 of the center pole portion 12 shown in FIG.
The magnetic body portion 12E is provided at a position rearward of the position of the outer peripheral surface 19c facing the rear of the speaker as the concave portion 19 on both sides of the outer peripheral surface facing the inner peripheral surface of the plate 22.
And an outer peripheral surface 19e facing the front of the speaker.

Therefore, the above-described speaker unit 1
0, in the gap 23 of the magnetic circuit 20, between the plate 22 and the outer peripheral surface 19c of the center pole portion 12 facing the rear of the speaker, as shown in FIG.
Also, between the plate 22 and the outer peripheral surface 19e of the center pole portion 12 facing the front of the speaker, the magnetic flux B
As a result, the range of the uniform magnetic field distribution in the gap 23 of the magnetic circuit 20 spreads forward and backward from the position of the thickness P of the plate 22 as shown by the broken line 9 in FIG.

The primary coil 1 which is a driving coil
Is a winding width L extending forward and rearward from the position of the thickness P of the plate 22, and is located in the range of the spread uniform magnetic field distribution.
The magnetic energy at the point is used efficiently.
Therefore, the sensitivity of the speaker is improved, the output sound pressure level is increased, and the distortion is reduced.

Further, by making the winding width L of the primary coil 1 larger than the thickness P of the plate 22, the primary coil 1 can be wound in one layer, and the length of the gap 23 of the magnetic circuit 20 is reduced. In this respect, the sensitivity of the speaker can be improved, and the output sound pressure level can be increased.

As shown in FIG. 6A, the outer peripheral surface 1
9c is a surface facing obliquely rearward of the speaker.
9e may be a surface facing obliquely forward of the speaker.
Further, as shown in FIG. 6B, the outer peripheral surface 19c may be a curved surface facing obliquely rearward of the speaker, and the outer peripheral surface 19e may be a curved surface facing obliquely forward of the speaker.

The above-described speaker unit 10 can be assembled by the following method. First, an opening 15 is formed in a flange portion 14 and a center pole portion 1 of a center pole yoke 11 to which a terminal plate 16 is attached.
2, the primary coil 1 is attached as shown in FIG. 2, FIG. 3 or FIG. Next, the coil lead wire 1 of the primary coil 1
7 is adhered to the peripheral surface of the center pole portion 12 to form an opening 15.
And soldered to the input terminal 18 on the terminal board 16.

Next, an adhesive is applied to the front surface of the flange portion 14 of the center pole yoke 11 so that the magnet 2
Put 1 on. At this time, the inner diameter of the magnet 21 is set to be equal to the outer diameter of the magnet guide 14a provided on the center pole yoke 11. In addition, magnet 2
An adhesive is applied to the front surface of 1 and the plate 22 is placed.

The speaker frame 35 is attached to the plate 22 in advance by caulking or the like. Alternatively, after completion of the magnetic circuit 20, the plate 22
The speaker frame 35 may be attached to the speaker frame by means such as screws. The following method is a case where the speaker frame 35 is attached to the plate 22 in advance.

Next, a gap guide (not shown) is inserted into the center pole portion 12 so that the inner diameter of the plate 22 and the outer diameter of the center pole portion 12 are concentric.
Next, a secondary coil 2 constituting a short coil and a coil spacer (not shown) are prepared.
The coil spacer is inserted into the inside of
The coil spacer is inserted into the center pole portion 12 so that the secondary coil 2 is located at the predetermined position 3.

Next, the outer periphery of the damper 34 is adhered to the speaker frame 35 and the inner periphery thereof is adhered to the secondary coil 2, respectively, and the cone 32 having the edge 31 on the outer periphery.
Attach the outer edge 31 and the gasket 36 to the speaker frame 35, and attach the inner periphery of the cone 32 to
Attach to secondary coil 2.

Next, after the adhesive is dried, the coil spacer is removed from the center pole portion 12, and the center cap 33 is bonded to the inner peripheral portion of the cone 32 or the tip of the secondary coil 2. After drying the adhesive, the magnet 21
Is completed, the assembly of the speaker unit 10 is completed.

FIG. 8 shows an example of a sound reproducing system using the speaker device of the present invention, in which sound is reproduced by a digital sound signal from a digital sound output device.

The digital audio output device 210 is a CD player, a DAT (Digital Audio Tape Recorder), or the like.
Stereo audio signals composed of left and right audio signals, which are digitized into 16 bits at a sampling frequency of z or 48 kHz, are output as serial data alternately for each sample of left and right audio data.

A 16-bit digital audio signal of serial data from the digital audio output device 210 is supplied to a serial / parallel converter 220, which separates the left and right digital audio signals from each other. Each of them is converted into parallel data, and the 16-bit left and right digital audio signals as the parallel data are converted into left and right speaker devices 100L, 100L.
00R.

In this example, the speaker devices 100L and 100R are respectively composed of a decoder 70 and a speaker driving circuit 4
0 and a speaker unit 10, and a decoder 70 generates a control signal, which will be described later, from a 16-bit digital audio signal converted into parallel data from the serial / parallel converter 220. The speaker unit 10 is supplied to the circuit 40 and driven by the speaker driving circuit 40.

The speaker unit 10 is the electromagnetically coupled speaker described above with reference to FIGS. 1 to 6, and in this example, the primary coil 1 as a drive coil is divided into fifteen coils 1A, 1B.
1N, 1P.

That is, in this example, the 16-bit digital audio signal from the serial / parallel converter 220 is linearly quantized with a 2's complement code as shown in FIG. Using the MSB (most significant bit) as a sign bit, as shown in FIGS. 9 and 10, the primary coil 1 is divided into fifteen coils 1A, 1B.
N, 1P, and the coil 1A is made to correspond to the LSB (least significant bit), for example, has two turns, and the coils 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1
J, 1K, 1L, 1M, 1N, 1P are converted to 15SB, 14
SB, 13SB, 12SB, 11SB, 10SB, 9S
B, 8SB, 7SB, 6SB, 5SB, 4SB, 3S
The number of turns is twice the number of turns of the coil corresponding to the next lower bit, such as 4 turns, 8 turns, 16 turns, etc., corresponding to B and 2SB.

FIG. 11 shows an example of the decoder 70 and the speaker drive circuit 40 shown in FIG. 8 in this case. The speaker drive circuit 40 includes 15 coils 1A to 1N and 1P of the primary coil 1. Correspondingly, there are 15 coil drive circuits 40A to 40N and 40P.

The respective coil drive circuits 40A
To 40N and 40P are constant current sources 41A to 41N and 41P.
And four FETs 5 as switching elements, respectively.
1 to 54 and the corresponding coils 1A to 1N and 1P are bridge-connected, and the FETs 51 and 53 are turned on.
When the FETs 52 and 54 are turned off, the current Ia of the corresponding constant current source flows in the corresponding coil in the plus direction, and when the FETs 51 and 53 are turned off and the FETs 52 and 54 are turned on, the corresponding constant current source Is caused to flow in the negative direction to the corresponding coil.

The currents of the constant current sources 41A to 41N and 41P are all set to the same current value as indicated by the current Ia. In the same coil drive circuit, FETs 51 to 54
Are turned on or off, no current flows through the corresponding coil.

The decoder 70 corresponds to the fifteen coils 1A to 1N and 1P of the primary coil 1, that is, the MSB of the digital audio signal from the serial / parallel converter 220.
15 control signal generation circuits 70A to 70N and 70P corresponding to the 15 bits except for the digital audio signal from the serial / parallel converter 220. MSB and
From the lower bits (LSB to 2SB) corresponding to the respective control signal generation circuits 70A to 70N and 70P, four control signals G1 to G4, which will be described later, are obtained, respectively.
The control signals G1 to G4 correspond to the FETs of the corresponding coil drive circuits 40A to 40N and 40P of the speaker drive circuit 40.
It is supplied to the gates 51-54.

When the MSB of the digital audio signal from the serial / parallel converter 220 is 0 and the corresponding lower bit is 1, the four control signals G1 to G4
1, G3 turns on the FETs 51 and 53, and the control signals G2 and G4 turn off the FETs 52 and 54. When the MSB is 0 and the corresponding lower bit is also 0, or when the MSB is 1, the corresponding When the lower bit to be set is also 1, the control signals G1 to G4 are at a level for turning off the FETs 51 to 54. When the MSB is 1 and the corresponding lower bit is 0, the control signals G1 and G3 are set to the FETs 51 and 54.
53 is a level to turn off, and control signals G2 and G4 are FETs
This is the level at which 52 and 54 are turned on.

Therefore, when the MSB is 0, only when a certain lower bit is 1, a current Ia flows in the corresponding primary coil in the plus direction. Conversely, when the MSB is 1, a certain lower bit is 0. Only when is the current Ia flowing in the negative direction to the corresponding primary coil.

The driving force F of the vibration system of the electromagnetically coupled speaker is
The product of the secondary current i induced in the secondary coil, the density B of the magnetic flux generated in the air gap of the magnetic circuit, and the length L of the secondary coil in the air gap of the magnetic circuit is represented by F = BLi. Since the magnetic flux density B and the length L are constant, the driving force F of the vibration system is proportional to the secondary current i induced in the secondary coil. The secondary current i induced in the secondary coil is proportional to the product of the signal current flowing through the primary coil and the number of turns (impedance) of the primary coil.

In the above-described example, the number of turns of each of the coils 1A to 1P of the primary coil 1 is set to be proportional to the weight of each bit excluding the MSB of the digital audio signal from the serial / parallel converter 220. Thus, when the current Ia flows as a signal current through a certain primary coil,
In the secondary coil 2, a secondary current having a current value proportional to the bit weight corresponding to the primary coil in a direction corresponding to the MSB value of the digital audio signal from the serial / parallel converter 220 is induced.

Therefore, the cone 32 to which the secondary coil 2 is fixed has an amount proportional to the weight of the bit corresponding to the primary coil in a direction corresponding to the MSB value of the digital audio signal from the serial / parallel converter 220. Only displaced,
In the speaker unit 10, sound is faithfully reproduced according to the digital sound signal from the serial / parallel converter 220.

In general, an electromagnetically coupled speaker is excellent in heat dissipation, can withstand a large input, and can reduce distortion. However, an electromagnetic coupling speaker in which a secondary current is induced in a secondary coil by a signal current flowing in a primary coil. The coupling force is reduced in a low frequency range of several kHz to 1 kHz or less, and it is difficult to reproduce sound up to 20 Hz necessary for reproducing sound. Therefore, the electromagnetically coupled speaker is mainly used as a speaker for reproducing high-frequency sound.

However, the digital audio signal from the serial / parallel converter 220 shown in FIG.
Each coil 1A of the primary coil 1 is digitized at a sampling frequency of 4.1 kHz or 48 kHz.
.About.1P are driven by digital signals of the same sampling frequency, so that several kHz of the audio signal before digitization
Even low frequency components such as z to 1 kHz or less have high frequencies exceeding 20 kHz as signal currents flowing through the coils 1A to 1P of the primary coil 1.

Therefore, the speaker unit 10 which is an electromagnetically coupled speaker enables reproduction in a low frequency range, thereby realizing a full-range speaker reproducing low to high frequencies.

As in the case of a general speaker, the vibration system of the speaker unit 10 is difficult to respond to high frequencies.
High frequency components exceeding Hz are hardly reproduced. Therefore, each of the coils 1A to 1P of the primary coil 1
Is driven by a digital signal having a sampling frequency of 44.1 kHz or 48 kHz, the sampling frequency component is hardly reproduced. Even if the sound is reproduced with a very small sound pressure, the sound exceeding 20 kHz can hardly be heard by the human ear, so that there is no trouble even when listening to music. Further, it is easy to intentionally form a mechanical filter having a stop band of 20 kHz or more and to incorporate the mechanical filter into the speaker unit 10.

Further, it is possible to realize a speaker device that reproduces sound directly by a digital sound signal without using a D / A converter and a power amplifier, that has a small distortion and a large maximum output.

The audio reproduction system shown in FIG. 8 integrates, for example, a serial-to-parallel converter 220 to a speaker drive circuit 40, connects this to a digital audio output device 210, and connects a speaker unit 10 thereto. Alternatively, the configuration from the serial / parallel converter 220 to the speaker unit 10 may be integrated and connected to the digital audio output device 210.

In the above-described example, the number of turns of each of the coils 1A to 1P constituting the primary coil 1 is set to a number of turns proportional to the weight of each bit excluding the MSB of the digital audio signal from the serial / parallel converter 220. In this case, the difference in the weight of each bit of the digital audio signal is reproduced, but the number of turns of each of the coils 1A to 1P is the same, and the constant current sources 41A to 41A of the corresponding coil drive circuits 40A to 40P By changing the current value of 41P,
The difference in the weight of each bit of the digital audio signal from the serial / parallel converter 220 can be reproduced.

FIG. 12 shows an example of this case. The 15 coils 1A to 1N and 1P constituting the primary coil 1 all have the same number of turns, for example, 10 turns, and the coils 1A to 1N, Constant current sources 41A to 41N, 4 of coil drive circuits 40A to 40N, 40P corresponding to 1P
The 1P currents Ia to In and Ip are changed as described later. The rest is the same as the example of FIG.

As described above, the driving force F of the vibration system of the speaker unit 10 is proportional to the secondary current i induced in the secondary coil 2, and the secondary current i is the signal current flowing through the primary coil 1. And the number of turns (impedance) of the primary coil 1.

For this reason, in this example, although omitted in FIG. 12, as shown in FIGS. 9 and 10, the 15SB of the digital audio signal from the serial / parallel converter 220 is used.
The current Ib of the constant current source of the coil driving circuit corresponding to the coil 1B corresponding to LSB is the current Ia of the constant current source 41A of the coil driving circuit 40A corresponding to the coil 1A corresponding to the LSB.
Is twice as large as That is, Ib = 2Ia.

The currents Ic, Id, Ie of the constant current sources of the coil drive circuits corresponding to the coils 1C, 1D, 1E,... Corresponding to 14SB, 13SB, 12SB.
b, Ic, Id...

Therefore, as in the example of FIG. 11, in the speaker unit 10, the cone 32 corresponds to the primary coil through which the signal current flows in the direction corresponding to the MSB value of the digital audio signal from the serial / parallel converter 220. The digital audio signal is shifted by an amount proportional to the weight of the corresponding bit, and the audio is reproduced faithfully to the digital audio signal from the serial / parallel converter 220.

Further, when the difference in the weight of each bit of the digital audio signal is reproduced by changing the current value of the constant current source, the primary coil 1 can be reduced to one.

FIG. 13 shows an example in that case. However,
In this example, when the 16-bit digital audio signal from the serial / parallel converter 220 is a natural binary code,
Alternatively, the digital audio signal of the 2's complement code as shown in FIG.
Is converted to a natural binary code.

In this example, the primary coil 1 is constituted by one coil, and currents Ia, Ib to In, Ip, I
q constant current sources 61A, 61B to 61N, 61P, 61Q
Are the switch circuits 62A, 62B to 62N, 6 respectively.
2P, 62Q, and switch circuits 62A,
62B to 62N, 62P, and 62Q are switched by the data of the corresponding bits of the digital audio signal from the serial / parallel converter 220.

That is, the serial / parallel converter 220
When a certain bit of the digital audio signal from is set to 1, the corresponding switch circuit is turned on, and the current of the corresponding constant current source flows through the primary coil 1. And 15
The current Ib of the constant current source 61B corresponding to SB is set to twice the current Ia of the constant current source 61A corresponding to LSB. Hereinafter, the current of the constant current source corresponding to each bit is set to the next lower bit. It is twice the current of the corresponding constant current source.

Therefore, in this example, in the speaker unit 10, the cone 32 is displaced in one direction by an amount proportional to the weight of each bit of the digital audio signal from the serial / parallel converter 220. The sound is reproduced faithfully to the digital sound signal from 220.

Even when the digital audio signal from the serial / parallel converter 220 is a 2's complement code as shown in FIG. 9, the coil drive circuits 40A to 40P as shown in FIG. The primary coil 1 can be made one by making it possible to switch by each bit data except the MSB of the digital audio signal.

Furthermore, the difference in the weight of each bit of the digital audio signal can be reproduced by a combination of the difference in the number of turns of the plurality of primary coils and the difference in the current value of the plurality of constant current sources.

FIG. 14 shows an example in that case. However,
Also in this example, when the 16-bit digital audio signal from the serial / parallel converter 220 is a natural binary code,
Alternatively, the digital audio signal of the 2's complement code as shown in FIG.
Is converted to a natural binary code.

In this example, the primary coil 1 is composed of 16 coils 1A, 1B... 1N, 1P, 1Q, and a block A including coils 1A to 1H and coils 1I to 1N,
Block I consisting of 1P and 1Q
A and 1I have 4 turns, coils 1B and 1J have 8 turns, coils 1C and 1K have 16 turns, and coils 1D and 1L have 32 turns.
Turns, coils 1E, 1M are 64 turns, coils 1F,
1N has 128 turns, coils 1G and 1P have 256 turns, and coils 1H and 1Q have 512 turns.

Further, constant current sources 61A to 61H of current Ia are connected to the coils 1A to 1H via switch circuits 62A to 62H, respectively.
For each of I to 1N, 1P, and 1Q, a constant current source 61
Constant current source 61 of the 16 ² times the current of A~61H current Ia
I to 61N, 61P, and 61Q are connected via switch circuits 62I to 62N, 62P, and 62Q, respectively, and the switch circuits 62A to 62N, 62P, and 62Q correspond to corresponding bits of the digital audio signal from the serial / parallel converter 220. Is switched according to the data of.

Therefore, as in the example of FIG. 13, in the speaker unit 10, the cone 32 is shifted in one direction by an amount proportional to the weight of each bit of the digital audio signal from the serial / parallel converter 220, The sound is reproduced faithfully according to the digital sound signal from the serial / parallel converter 220.

[0081] In this example, the minimum number of turns of the coil 1A, 1I and maximum number of turns of the coil 1H, the number of turns ratio between 1Q, 4: 512 = 1: 2 7 and so small And the ratio of the current value between the minimum current value and the maximum current value is 1:16 ² = 1:
It can be reduced so that 2 ^8.

In this example, the coils 1A to 1N, 1P, 1
Q is, for example, as shown in FIG. 15, the magnetic portions 12C and 12E of the center pole portion 12 described above with reference to FIG.
In between, the coil 512 having the maximum of 512 turns is wound inside, the coil 1Q having the same 512 turns is wound outside the coil 1H, and the coils 1G and 1P having 256 turns are vertically moved outside the coil 1Q. (Front side and rear side) and wound, 128, 64, 32, 1
6, 8 and 4 turn coils 1F, 1E, 1D, 1C, 1
B, 1A are wound around the outside of the coil 1G such that the smaller the number of turns, the more inward in the front-rear direction, and the coil 1 having 128, 64, 32, 16, 8, and 4 turns, respectively.
N, 1M, 1L, 1K, 1J, and 1I are wound around the outside of the coil 1P so that the smaller the number of turns, the more inside the coil. According to this, each coil 1A-1
In N, 1P, and 1Q, the pitch for one turn can be equalized.

In each of the above-described examples, when the digital audio signal for driving the primary coil 1 of the speaker unit 10 is linearly quantized and the primary coil 1 is composed of a plurality of coils, the plurality of coils are used. Number of turns, or each bit excluding MSB of digital audio signal, or MSB
In the case where the current value of the constant current source corresponding to each bit including is changed in geometric progression, when the digital audio signal driving the primary coil 1 is non-linearly quantized, Depending on the mode of quantization, when the primary coil 1 is composed of a plurality of coils, it corresponds to the number of turns of the plurality of coils, or each bit excluding the MSB of the digital audio signal, or each bit including the MSB. The current value of the constant current source may be changed.

FIG. 16 shows another example of an audio reproduction system using the speaker device of the present invention. In this example, an analog audio signal Ao from an analog audio output device 510 such as a cassette player or an FM tuner is transmitted to a chopper 52.
0, and the chopper 520, as shown by the analog audio signal Ac in FIG. 17, has a frequency higher than the audio frequency, that is, 20 kHz, which is called the upper limit of the audio frequency.
Chopping is performed at a frequency fc exceeding z.

However, the chopping frequency fc is
It is desirable that the frequency be about twice as high as 20 kHz, for example, 40 kHz. Further, the time width of the chopping period is sufficiently shorter than the chopping cycle Tc, and is, for example, 1/10 of the chopping cycle Tc.

Then, the chopped analog audio signal Ac from the chopper 520 is supplied to the power amplifier 5.
The signal is amplified at 30 and supplied to the primary coil 1 of the speaker unit 10 described above. However, the speaker unit 1
0 indicates that the primary coil 1 is one.

As described above, the speaker unit 10 which is an electromagnetically coupled speaker has an electromagnetic coupling force in which the secondary current i is induced in the secondary coil 2 by the signal current flowing through the primary coil 1 and is several kHz to 1 kHz or less. It becomes smaller at low frequencies.

However, according to the example of FIG. 16, the analog audio signal is intermittently transmitted at a frequency fc higher than the audible frequency and supplied to the primary coil 1 of the speaker unit 10, so that the low-frequency component of the analog audio signal is also reduced. The signal current flowing through the primary coil 1 has a high frequency exceeding 20 kHz. Therefore, reproduction up to low frequencies can be performed by the speaker unit 10 which is an electromagnetically coupled speaker.

FIG. 18 shows another example of the speaker device of the present invention, which is a case of a speaker unit of a dynamic speaker. In the speaker unit 90 of this example, a concave portion 19 described later is formed around the tip of the center pole portion 12 of the center pole yoke 11.

A magnet 21 is adhered to the front surface of the flange portion 14 of the center pole yoke 11, and a plate 22 is adhered to the front surface of the magnet 21. A magnetic circuit 20 having an air gap 23 between the magnetic circuit 20 and the inner peripheral surface is formed.

In the gap 23 of the magnetic circuit 20, the voice coil bobbin 6 and the voice coil 5 wound therearound are inserted. The voice coil bobbin 6 has an inner peripheral portion of a cone 32 having an edge 31 on an outer peripheral portion, a center cap 3
3, and the inner periphery of the damper 34 are attached.
A speaker frame 35 is attached to the plate 22, and the outer edge 31 of the cone 32 and the gasket 36 are attached to the speaker frame 35, and the outer periphery of the damper 34 is attached to the speaker frame 35.

A terminal plate 38 is mounted on the speaker frame 35, and the beginning and end of winding of the voice coil 5 pass through the inside of the voice coil bobbin 6 and the coil lead 3
7 and the coil lead wire 37 is connected to the input terminal 39 on the terminal plate 38.

Also in this example, the winding width of the voice coil 5, which is a driving coil, is made larger than the thickness P of the plate 22, and the width of the plate
Extending from the position of the thickness P to the front side and the rear side.

In addition, the center pole portion 12 is
9, a magnetic portion is provided at a position on the front side and the rear side from the position of the winding width of the voice coil 5, and has an outer peripheral surface facing obliquely rearward and an outer peripheral surface facing obliquely forward of the speaker. .

Therefore, also in the speaker unit 90 of the dynamic speaker, similarly to the speaker unit 10 of the electromagnetically coupled speaker shown in FIG.
A magnetic flux is also generated between the plate 22 and the outer peripheral surface of the center pole portion 12 that faces obliquely forward, and the plate 22. As shown by the broken line 9 in FIG. 7, the range of the uniform magnetic field distribution in the space 23 extends forward and backward from the position of the thickness P of the plate 22.

The voice coil 5 serving as a driving coil
Is a winding width extending forward and rearward from the position of the thickness P of the plate 22, and is located in this widened range of the uniform magnetic field distribution, so that the magnetic energy in the air gap 23 of the magnetic circuit 20 is reduced. It will be used efficiently. Therefore, the sensitivity of the speaker is improved, the distortion is reduced, and the allowable input is increased.

The above-described speaker unit 90 can be assembled by the following method. First, an adhesive is applied to the front surface of the flange portion 14 of the center pole yoke 11 having the concave portion 19 formed in the center pole portion 12, and the magnet 21 is mounted thereon. At this time, the inner diameter of the magnet 21 is set to be equal to the outer diameter of the magnet guide 14a provided on the center pole yoke 11.

Next, an adhesive is applied to the front surface of the magnet 21 and the plate 22 is placed thereon. At this time, a gap guide (not shown) is inserted into the center pole section 12 so that the inner diameter of the plate 22 and the outer diameter of the center pole section 12 are concentric.

The terminal plate 3 is provided on the plate 22 in advance.
The speaker frame 35 to which the speaker 8 has been attached is attached by means such as caulking. Alternatively, the magnetic circuit 20
After completion of the above, the speaker frame 35 to which the terminal plate 38 is attached may be attached to the plate 22 by means such as screws. The following method is a case where the speaker frame 35 is attached to the plate 22 in advance.

Next, a voice coil bobbin 6 around which the voice coil 5 is wound, and a coil spacer (not shown) are prepared, and the coil spacer is inserted into the inner diameter of the voice coil bobbin 6, and a predetermined position of the gap 23 of the magnetic circuit 20 is set. The coil spacer is inserted into the center pole portion 12 so that the voice coil 5 is located at the center.

Next, the outer peripheral portion of the damper 34 is adhered to the speaker frame 35, the inner peripheral portion is adhered to the voice coil bobbin 6, respectively, and the outer peripheral edge 31 of the cone 32 having the outer peripheral edge 31; 36
Is attached to the speaker frame 35, and the inner peripheral portion of the cone 32 is attached to the voice coil bobbin 6.

Next, after the adhesive is dried, the coil spacer is removed from the center pole portion 12 and the center cap 33 is bonded to the inner peripheral portion of the cone 32 or the tip of the voice coil bobbin 6. After the adhesive is dried, if the magnet 21 is magnetized, the assembly of the speaker unit 90 is completed.

In the speaker unit 90 of the dynamic speaker, the voice coil 5 as a driving coil thereof is driven by a digital audio signal, similarly to the primary coil 1 as a driving coil of the speaker unit 10 of the electromagnetically coupled speaker described above. be able to. Further, the voice coil 5 can be driven by an analog audio signal.

[0104]

As described above, according to the present invention, the efficiency of the speaker is improved, the output sound pressure level is increased, and the distortion is improved by efficiently utilizing the magnetic energy in the gap of the magnetic circuit. And the allowable input can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a speaker device according to the present invention.

FIG. 2 is a diagram illustrating an example of a drive coil unit of the speaker device of FIG. 1;

FIG. 3 is a diagram illustrating another example of the drive coil unit of the speaker device of FIG. 1;

FIG. 4 is a diagram illustrating still another example of the drive coil unit of the speaker device of FIG. 1;

FIG. 5 is a diagram provided for explaining a main part of the speaker device of FIG. 1;

FIG. 6 is a diagram provided for explaining a main part of the speaker device of FIG. 1;

FIG. 7 is a diagram provided for explaining a main part of the speaker device of FIG. 1;

FIG. 8 is a block diagram showing an example of a sound reproduction system using the speaker device of the present invention.

FIG. 9 is a diagram provided for describing an example of a digital audio signal.

FIG. 10 is a diagram showing an example of a coil configuration of the speaker device of the present invention.

FIG. 11 is a connection diagram illustrating an example of the speaker device of the present invention.

FIG. 12 is a connection diagram showing another example of the speaker device of the present invention.

FIG. 13 is a connection diagram showing still another example of the speaker device of the present invention.

FIG. 14 is a connection diagram showing still another example of the speaker device of the present invention.

FIG. 15 is a diagram illustrating an example of winding a drive coil of the speaker device of FIG. 14;

FIG. 16 is a block diagram showing another example of an audio reproduction system using the speaker device of the present invention.

FIG. 17 is a diagram provided for description of the audio reproduction system in FIG. 16;

FIG. 18 is a sectional view showing another example of the speaker device of the present invention.

FIG. 19 is a cross-sectional view illustrating an example of a conventional speaker device.

[Explanation of symbols]

10, 90 ... speaker unit, 1, 1A, 1B, 1
C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1
K, 1L, 1M, 1N, 1P, 1Q ... primary coil, 2 ...
Secondary coil, 5: Voice coil, 11: Center pole and yoke, 12: Center pole section, 12C, 12E ...
Magnetic parts, 19c, 19e: outer peripheral surface, 20: magnetic circuit, 21: magnet, 22: plate, 23: air gap,
32: cone, 40: speaker drive circuit, 40A-40
P: coil drive circuit, 41A to 41P, 61A to 61Q
... constant current source

Claims (4)

[Claims] 1. A magnetic circuit formed by a center pole yoke, a plate, and a magnet and having a gap between a center pole portion of the center pole yoke and the plate, wherein a magnetic circuit is provided in the gap of the magnetic circuit. A drive coil having a winding width extending from the position of the thickness of the plate to the front side and the rear side of the speaker, and the center pole portion being located on the front side and the rear side of the speaker from the position of the winding width of the drive coil. The speaker device includes a magnetic portion at each of the following positions, and has an outer peripheral surface facing rearward or obliquely rearward of the speaker and an outer peripheral surface facing forward or obliquely forward of the speaker. 2. A speaker unit comprising: a speaker unit; and a speaker drive circuit, wherein the speaker unit is formed by a center pole yoke, a plate, and a magnet, and is provided between a center pole portion of the center pole yoke and the plate. A drive coil having a winding width extending from the position of the thickness of the plate to the front side and the rear side of the speaker is disposed in the gap of the magnetic circuit, and the center pole portion is provided in the gap. A magnetic body portion is provided at a position on the front side and the rear side of the speaker from the position of the winding width of the drive coil, respectively, and an outer peripheral surface facing the rear or oblique rear of the speaker, and facing the front or oblique front of the speaker. Wherein the speaker drive circuit has a digital sound for the drive coil of the speaker unit. A speaker device driven by a voice signal. 3. The speaker device according to claim 1, wherein the drive coil is a primary coil fixed between the respective magnetic portions of the center pole portion, and a diaphragm is provided in the gap. And a secondary coil constituting a short coil fixed to the speaker device. 4. The speaker device according to claim 1, wherein the drive coil is fixed to a diaphragm and is a voice coil disposed in the gap.