JPH1056684A - Speaker system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve middle and high sound frequency characteristics and sound quality of middle and high sound frequency signals of a digital driven electromagnetic coupling speaker. SOLUTION: A primary coil 24 to which a current in response to an input voice signal is supplied is provided in the vicinity of an air gap GP in a magnetic circuit. A secondary coil unit 25 consisting of a short-circuit coil in which a current in response to the current flowing through the primary coil 24 is induced and to which a main diaphragm 29 is fitted is provided in the air gap GP, A sub diaphragm 26 is formed to the secondary coil unit 25 as an integrated component. The primary coil 24 is driven by the digital voice signal.

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 first magnetic yoke and a plate with a magnet interposed between a first magnetic yoke called a pole piece and a second magnetic yoke called a plate. The speaker unit in which the primary coil is fixed in the gap of the magnetic circuit, and is fixed to the diaphragm so as to face the secondary coil, and the secondary coil is arranged in the gap of the magnetic circuit, is electromagnetically coupled (electromagnetically coupled). It has been put to practical use as an induction speaker.

In this electromagnetically coupled speaker, a secondary current is induced in the secondary coil by a signal current flowing through the primary coil, and the secondary current is converted into a secondary current by an interaction with a magnetic flux generated in a gap in the magnetic circuit. A driving force corresponding to 2
The diaphragm to which the next coil is fixed vibrates.

[0005] In this electromagnetically coupled speaker, the primary coil through which the signal current flows is fixed to the first and / or second magnetic yoke made of a magnetic material such as iron. There is an advantage that can be tolerated Further, if the secondary coil is formed of a non-magnetic conductive material, for example, aluminum, or a short coil formed of a pipe or a cylindrical body forming a one-turn coil, distortion can be reduced.

On the other hand, a conductive speaker in which a voice coil is disposed in a gap of a magnetic circuit has been put into practical use. In this conductive speaker, power is supplied to the voice coil and the speaker is unnecessary for a vibration system including the voice coil. The voice coil is joined to a terminal provided on the speaker frame by a lead wire made of a tinsel wire so as not to give an excessive vibration or resistance.

Further, in this conductive speaker, the voice coil is divided into the number of bits of the digital audio signal, and each coil is directly associated with each bit of the digital audio signal, and directly receives the data of each bit. It is considered to be driven.

[0008]

As described above, the electromagnetically coupled speaker is excellent in heat dissipation, has the advantage of withstanding a large input, and can reduce distortion.
However, if the length of the air gap in the magnetic circuit is increased, the sensitivity of the loudspeaker is reduced, so that the number of turns of the primary coil and the secondary coil cannot be increased.

Therefore, the inductance of the primary coil and the secondary coil cannot be increased, and the electromagnetic coupling force that induces the secondary current in the secondary coil by the signal current flowing through the primary coil is several kHz to 1 kHz. It becomes smaller in the following low frequency range, and it is impossible to reproduce up to 20 Hz necessary for reproducing sound. Therefore, the electromagnetic coupling speaker
It is mainly used only as a speaker for reproducing high-pitched sounds.

On the other hand, as described above, in a conductive speaker, a voice coil is joined to a terminal provided on a speaker frame by a lead wire made of a tinsel wire. Also,
In a conductive speaker, it has been considered that a voice coil is divided into the number of bits of a digital audio signal, and each coil is directly driven by data of each bit of the digital audio signal.

However, at present, when digitizing an audio signal, the digital audio signal is generally 16 bits in order to faithfully reproduce the audio. Therefore, when a voice coil is driven by a digital audio signal in a conductive speaker, one speaker needs 16 pairs of lead wires.

However, the tinsel wire, which is the lead wire, swings greatly with the vibration of the voice coil, so that the distance between them cannot be reduced. Therefore, it is very difficult to provide as many as 16 pairs of tinsel wires on a small speaker.

Therefore, the inventor of the present invention has proposed a novel speaker device that enables reproduction to a low frequency range by driving an electromagnetically coupled speaker with a digital signal.

FIG. 16 is a sectional view showing the structure of an example of an electromagnetically coupled speaker unit used in the novel speaker device.

As shown in FIG. 16, a speaker unit of the electromagnetic coupling type of this embodiment has a cylindrical center pole portion 1a.
Yoke 1 provided with a disk-shaped flange portion 1b
And a donut-shaped plate 2 forming a second yoke
A magnetic circuit is constituted by a donut-shaped magnet 3 disposed between the flange portion 1b of the first yoke 1 and the plate 2, and a magnetic gap GP between the plate 2 and the center pole portion 1a.

The magnet 1 is mounted on the flange 1b.
And a magnet guide 15 composed of a step for making the center position of the center pole portion 1a coincide with that of the center pole portion 1a. When assembling the magnetic circuit, a jig called a gap guide is used so that the center of the center pole portion 1a and the center of the plate 2 coincide with each other.
Of the plate 22 and the inner peripheral surface of the plate 22.

A drive coil as a primary coil is arranged on one or both of the outer peripheral surface of the center pole portion 1a and the inner peripheral surface of the plate 2 opposed to each other with the magnetic gap GP interposed therebetween. In this embodiment, the primary coil 4 is arranged on the outer peripheral surface of the center pole portion 1a.
In order to arrange the primary coil 4, the center pole portion 1a
In the vicinity of the top, a small diameter portion 1c having a length corresponding to the winding width of the primary coil 4 is provided, and the primary coil 4 is provided in the small diameter portion 1c.

In the case of this example, the primary coil 4 comprises a number of coil groups corresponding to the number of bits of the input digital signal. For example, when the input digital signal is a 16-bit / 1-sample binary code in which the most significant bit MSB is a sign bit (positive or negative bit), the primary coil 24 excludes the MSB corresponding to the number of bits. Fifteen coils are provided.

Each of the 15 coils has a number of turns corresponding to the weight of each corresponding bit. If the digital audio signal is linearly quantized, the number of turns of the 15 coils is determined by the least significant bit LSB.
To the geometric series corresponding to each bit from to the most significant bit MSB. For example, if the coil corresponding to LSB has two turns, the coil corresponding to 15SB is four turns, and the coil corresponding to 14SB is eight turns.
The number of turns is increased, such as 16 turns for the coil corresponding to 13 SBs, and so on.

Lead wire pair 1 derived from primary coil 4
7 (actually, there are 15 pairs, but only one pair is shown in the figure for simplicity of description) passes through the through hole 14 provided in the flange portion 1b of the first magnetic yoke 1 and passes through the flange portion 1b.
Extended to the back of the Each of the lead wire pairs 17 is connected to fifteen input terminals 18 (only one input terminal is shown in the figure for simplicity of description) provided on the back side of the flange portion 1b.

In this case, in order to radiate heat from the lead wire pair 17, the lead wire pair 17 is adhered to the outer surface of the center pole portion 1a and is led out in the direction of the flange portion 1b of the first magnetic yoke 1. .

Then, a secondary coil 5C composed of a short coil that is electromagnetically coupled to the primary coil 4 is inserted into the gap GP. In the case of this example, as shown in FIG. 17, the secondary coil units 5 constituting the secondary coil 5C are each made of a non-magnetic material, and a conductive material, for example, aluminum is formed in a cylindrical shape. It is a one-turn short coil. In this example, the coil bobbin is omitted, and the secondary coil unit 5 is constituted only by the short coil 5C. Of course, a secondary coil unit can also be configured by winding a coil around the coil bobbin and short-circuiting both ends.

The secondary coil unit 5 having the above configuration
Is attached to the speaker frame 11 via the damper 10. A cone paper 9 as an example of a diaphragm is attached to the secondary coil unit 5 by bonding. The cone paper 9 is attached to the speaker frame 11 by a gasket 12 via a flexible edge 9e. Finally, the cap 13 is attached to the cone paper 9 or the top edge of the secondary coil unit 5 by bonding.

By applying signal inputs corresponding to the respective bits of the digital signal to the input terminals 18 corresponding to the number of bits of the electromagnetically coupled speaker described above, each of the plurality of coils constituting the primary coil 4 can be provided. In accordance with the flowing current, a current is induced in the short coil as the secondary coil 5C, and the secondary coil unit 5 vibrates up and down according to Fleming's left-hand rule due to interaction with the magnetic flux in the gap GP.

In this case, the sampling frequency for digitizing the audio signal is 44.1 kHz or 48 k.
20k which is said to be the upper limit of audible frequency such as Hz
The frequency is higher than twice the Hz. Therefore, a low-frequency component such as several kHz to 1 kHz or less of the audio signal before being digitized has a high frequency exceeding 20 kHz as the digital audio signal.

In addition, the electromagnetically coupled speaker is designed so that the length of the air gap in the magnetic circuit is reduced so that the sensitivity of the speaker does not decrease, and the number of turns of the primary coil and the secondary coil is reduced. The frequency of the signal current flowing through the
When the frequency is higher than z, the electromagnetic coupling force does not decrease and the sound can be reproduced.

In the loudspeaker device of the present invention configured as described above, the primary coil of the electromagnetically coupled speaker is driven by the digital audio signal.
The low-frequency component of the audio signal before being digitized also has a high frequency exceeding 20 kHz as a signal current flowing through the primary coil. Therefore, reproduction up to low frequencies can be performed by the electromagnetically coupled speaker.

Like a general loudspeaker, the vibration system of the loudspeaker unit is hardly responsive to high frequencies, especially at 20 kHz.
High-frequency components exceeding the above are hardly reproduced. Therefore, the plurality of primary coils are 44.
Even when driven by a digital signal having a sampling frequency of 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 incorporate it into the speaker unit.

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

By the way, in this electromagnetically coupled speaker, the mid-high range sound is radiated from the center of the cone paper 9 and the cap 13. For this reason, the secondary coil unit 5, the cone paper 9 and the cap 13 need to be firmly bonded and fixed for the vibration in the middle and high frequencies.

However, the cone paper 9 and the cap 13 and aluminum as the secondary coil unit are
Since they are adhered by an adhesive such as an epoxy agent, the strength is lower than that of an integrated product, so that the mid-high range characteristics and the mid-high range sound quality may be deteriorated.

In view of the above, the present invention provides a speaker device using the above-described novel electromagnetically coupled speaker unit, which can improve the mid-high range characteristics and the mid-high range sound quality. With the goal.

[0034]

In order to solve the above-mentioned problems, according to the present invention, a primary coil fixed to a portion near a gap in a magnetic circuit, and the primary coil disposed in the gap, and
A secondary coil composed of a short coil in which a secondary current corresponding to a current flowing in the secondary coil is induced, and a secondary coil attached to a coil bobbin of a secondary coil unit in which the secondary coil is formed, and via an edge portion. The main diaphragm fixed to the speaker frame and the above-described 2
A speaker unit including a sub-diaphragm attached to a next coil, and a speaker driving circuit for driving the primary coil of the speaker unit by a digital audio signal are provided.

The secondary coil has a cylindrical shape made of a non-magnetic and conductive material, and the coil bobbin is omitted to constitute a secondary coil unit. The secondary diaphragm is formed of a secondary coil having this cylindrical shape. It is good to form as an integral part.

According to the present invention having the above-described structure, middle and high range sounds are reproduced by the sub-diaphragm formed as an integral part of the secondary coil unit. Therefore, the mid-high range characteristics are improved, and the sound quality in the mid-high range is improved.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a speaker device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of one embodiment of a speaker unit used in a speaker device according to the present invention.

As shown in FIG. 1, the speaker unit of this embodiment is composed of an electromagnetically coupled speaker, and is different from the structure of the speaker unit of the above-described example of FIG. 16 only in the structure of the secondary coil unit. Other parts are almost the same.

That is, in the speaker unit of this example, a first yoke 21 having a columnar center pole portion 21a and a disk-shaped flange portion 21b, and a donut-shaped plate 22 forming a second yoke. And the first
A magnetic circuit is formed by a donut-shaped magnet 23 disposed between the flange portion 21b of the yoke 21 and the plate 22, and a magnetic gap GP between the plate 22 and the center pole portion 21a.

The magnet 23 is mounted on the flange 21b.
And a magnet guide 35 formed of a step to make the center position of the center pole portion 21a coincide with that of the center pole portion 21a.

The outer peripheral surface of the center pole portion 21a opposed to each other with the magnetic gap GP therebetween,
A drive coil as a primary coil is disposed on one or both of the inner peripheral surface portion and the inner peripheral surface portion. In this example,
Similarly to the above-described example, the primary coil 24 is disposed on the outer peripheral surface of the center pole portion 21a. In order to dispose the primary coil 24, a small-diameter portion 21c having a length corresponding to the winding width of the primary coil 24 is provided near the top of the center pole portion 21a.
The primary coil 24 is fixed to the small diameter portion 21c.

This primary coil 24 is also
The input digital signal is composed of a number of coil groups corresponding to the number of bits of the input digital signal.
6 bits / 1 sample, and the most significant bit MSB is a sign bit (positive / negative bit). For example, in the case of a 2 'complement code, the primary coil 24 has 15 bits corresponding to the number of bits. A coil is provided.

Each of the 15 coils has a number of turns corresponding to the weight of the corresponding bit. If the digital audio signal is linearly quantized, the number of turns of the 15 coils is determined by the least significant bit LSB.
To the geometric series corresponding to each bit from to the most significant bit MSB.

When the analog audio signal is non-linearly quantized and converted into a digital audio signal, the number of turns of the plurality of coils constituting the primary coil 24 is, as described above, a geometric series. It is not changed, but changed according to the non-linear characteristic of the non-linear quantization.

FIG. 2A shows an example of the primary coil 24. This example is a case where the primary coil 24 has an air-core coil configuration. That is, as shown in FIG. 2A, the primary coil 24 has fifteen coils LA having different numbers of turns.
~ LG, LI ~ LP, each coil LA ~ LG, L
From I to LP, a pair of lead wires 37a to 37g and 37i to 37p at the beginning and end of the winding are derived. The primary coil 24 is inserted into and adhered to the small diameter portion 21c of the center pole portion 21a shown in FIG.
It is fixed in the state as shown in FIG.

The primary coil 24 may be formed by winding a wire around a magnetic bobbin 36 as shown in FIG. 3A, or as shown in FIG. 3B.
The wire may be directly wound around the small diameter portion 21c of 1a and attached.

The fifteen pairs of lead wires 37 a to 37 p derived from the primary coil 24 pass through one or a plurality of through holes 34 provided in the flange part 21 b of the first magnetic yoke 21, and It extends to the back side of the portion 21b. Each of these lead wire pairs 37a to 37p (in FIG. 1, only one pair is represented as 37) is provided with 15 input terminals 38a to 38p (represented in FIG. 1) provided on the back side of the flange portion 21b. (Only one is described as a number 38).

In this case, in order to radiate heat from the lead wire pairs 37a to 37p, the lead wire pairs 37a to 37p are adhered to the outer surface of the center pole portion 21a and are directed toward the flange portion 21b of the first magnetic yoke 21. Is derived. In addition,
Instead of bonding, as shown in FIG. 3B, for example, a paper 39 is wound from above the lead wire pair of the center pole portion 21a, and the lead wire pair is used for the lead wire pair of the center pole portion 21a.
You may make it press so that it may contact a side.

In this embodiment, a secondary coil 25C made of a short coil electromagnetically coupled to the primary coil 24 is inserted into the gap GP. In the case of this example, the secondary coil 25C is a secondary coil unit 2
5, formed as such. Secondary coil unit 2
5 can be constructed by inserting a secondary coil made of a cylindrical ring into a coil bobbin, or can be constructed by winding a short-circuited coil around the coil bobbin by connecting both ends to each other. As in the example, and as shown in FIG. 4, a non-magnetic and conductive material, for example, aluminum is formed in a cylindrical shape,
The coil bobbin is omitted by the secondary coil 25C which is a short-turn coil, and the secondary coil unit 25
Is composed.

Then, as shown in FIG. 4, a sub diaphragm 26 is formed integrally with the secondary coil unit 25. The sub diaphragm 26 is mainly for reproducing and radiating the sound in the middle and high frequencies, and has a predetermined inclination and a shape of a bottom. The integrated component 27 composed of the secondary coil unit 25 and the sub diaphragm 26 forms a part of the sub diaphragm 26 by performing, for example, a processing called “spatching” on a cylindrical aluminum ring. Is molded.

The auxiliary bobbin 28 or the secondary coil 25C is fixedly disposed on the outer peripheral portion of the secondary coil unit 25 above the magnetic gap GP of the integrated component 27 having the above configuration. Then, by attaching the auxiliary bobbin 28 or the secondary coil 25C to the speaker frame 31 via the damper 30, the component 27 including the secondary coil unit 25 and the sub diaphragm 26 is attached.

A cone paper 29 as an example of a main diaphragm is attached to the auxiliary bobbin 28 or the secondary coil 25C. The cone paper 29 is attached to the speaker frame 31 by a gasket 32 via a flexible edge 29e.

For example, as shown in FIG. 5A, the auxiliary bobbin 28 is a bobbin 28 B
And a reinforcing paper 28P wound thereon. The inner diameter of the bobbin 28B is set substantially equal to the outer diameter of the secondary coil unit 25. FIG. 6 shows a state in which a predetermined position of the secondary coil unit of the component 27 is adhesively fixed to the auxiliary bobbin 28 in the example of FIG. 5A.

As the auxiliary bobbin 28, one having a spiral bobbin 28S as shown in FIG. 5B can be used.

The method of assembling the speaker unit having the above configuration will be described below.

As shown in FIG. 2B, the primary coil 24
Is inserted into the small diameter portion 21c above the center pole portion 21a and adhered.

Next, a pair of lead wires 37a from the fifteen coils LA to LA and LI to LP constituting the primary coil 24
To 37g and 37i to 37p are pulled out to the back side of the yoke 21 through the through holes 34, and the input terminals 38a to 3p are pulled out.
Solder to 8g and 38i-38p and fix. In addition, the lead wire portion in contact with the center pole portion 21a is bonded to the center pole portion 21a for the purpose of heat dissipation. The above-described fixing of the primary coil 24 is performed in a process before the assembly of the magnetic circuit.

Next, an adhesive is applied to the front surface of the flange portion 21b of the yoke 21 and the magnet 23 is placed thereon. The inner diameter of the magnet 23 and the outer diameter of the magnet guide 35 formed as a step between the front surface of the flange portion 21 are formed. And the center pole portion 21a and the magnet 23
Are aligned so that the centers of are almost coincident.

Next, an adhesive is applied to the upper surface of the magnet 23 and the plate 22 is placed. Then, a jig called a gap guide is inserted so that the inner diameter of the plate 22 and the outer diameter of the center pole portion 21a are concentric.

The speaker frame 31 is attached to the plate 22 in advance by caulking or the like. Alternatively, after the magnetic circuit is completed, the speaker frame 31 may be attached to the plate 22 by means such as screws.

After the adhesive between the plate 22 and the magnet 23 has dried, the gap guide is
Pull out from a. This completes the main body of the speaker.

Next, a jig called an auxiliary bobbin 28 or a secondary coil 25C and a coil spacer is prepared. This coil spacer is a jig whose outer diameter matches the inner diameter of the auxiliary bobbin 28 or the secondary coil 25C, and whose inner diameter matches the outer diameter of the center pole portion 21a.

Then, the coil spacer is inserted into the inside of the auxiliary bobbin 28 or the secondary coil 25C, and the positioning is performed so that the auxiliary bobbin 28 or the secondary coil 25C comes to a predetermined position above the gap GP. The coil spacer is inserted into the center pole part 21a.

Next, in this state, the outer peripheral portion of the damper 30 is adhered and fixed to the speaker frame 31 and the inner peripheral portion of the damper 30 is adhered to the outer peripheral portion of the auxiliary bobbin 28 so that the secondary coil unit 25 is formed. Center pole part 21a
In the direction of the axis of.

Next, the outer peripheral portion of the cone paper (main diaphragm) 29 with the edge 29e is bonded and fixed to the outer peripheral portion of the speaker frame 31 via the gasket 32. Further, the inner peripheral portion of the cone paper 29 is bonded and fixed to the auxiliary bobbin 28 or the outer peripheral portion of the secondary coil 25C. After the adhesive is dried, the coil spacer is pulled out from the center pole portion 21a.

When the damper 30 and the cone paper 29 are attached to the secondary coil 25C, the speaker 33 is completed by bonding the cap 33 to the vicinity of the top of the sub diaphragm 26 and magnetizing the magnet 23.

Next, the secondary coil unit 2 shown in FIG.
The part of the secondary coil unit 25 of the integrated component 27 with the sub-diaphragm 26 is inserted into the inner peripheral side of the auxiliary bobbin 28, and the secondary coil 25C comes to a predetermined position in the magnetic gap GP. After adjusting the position as described above, the adhesive is fixed. At this time,
A coil spacer different from the above is prepared, and it is inserted between the secondary coil unit 25 and the center pole portion 21a.

After the adhesive between the auxiliary bobbin 28 and the component 27 has dried, the coil spacer is removed from the center pole portion 21.
Pull out from a.

Then, the cap 33 is bonded to the vicinity of the top of the sub diaphragm 26. After the adhesive is dried, the magnet 23 is magnetized, and the speaker device is completed.

The input terminals 38a to 38g and 38i to 38p of the speaker unit of the electromagnetic coupling type described above
By adding a signal input corresponding to each bit of the digital signal,
Depending on the current flowing through the primary coil 24, the secondary coil 25
A current is induced in C, and the secondary coil unit 25 vibrates up and down according to Fleming's left-hand rule due to interaction with the magnetic flux in the gap GP. In this case, the change period of the digital signal is the sampling frequency of 44.1k.
Hz or 48 kHz, and the inductive coupling force between the secondary coil 25C and the primary coil 24 does not decrease, and it is possible to reproduce from a low tone to a middle and high tone range.

In the electromagnetically coupled speaker unit of this example, the secondary coil 25C (secondary coil unit 2
5) is formed in an aluminum cylindrical shape, and the sub-diaphragm 26 for middle and high sounds is provided integrally therewith. Therefore, the Young's modulus of the joint between the secondary coil unit 25 and the sub-diaphragm 26 is , Is very large compared to bonding, and has high rigidity, so that deterioration of the mid-high range characteristics and the sound quality of the mid-high range is small.

That is, since the bonding portion between the cone paper 29 as the main diaphragm and the secondary coil unit 25 has a small Young's modulus, there is a possibility that the mid-high range characteristics and the mid-high range sound quality may be deteriorated. The sub diaphragm 26 provided integrally with the secondary coil unit 25
, The middle-high range characteristics and the sound quality of the middle-high range are improved.

Although the above-described embodiment is an example in which the secondary coil unit is constituted only by the secondary coil composed of the cylindrical short coil, the cylindrical short coil is inserted into the bobbin or the short coil is inserted into the bobbin. It may be wound. In that case, the sub diaphragm is provided as an integral part with the bobbin of the secondary coil unit.

In this specification, the term “integral” is not limited to the case of processing an integrated object such as a spatula drawing, but it is not limited to welding. It also includes those which are joined and integrated into one component by a joining method such as welding or welding.

Next, an example of an audio reproduction system using the speaker unit according to the present invention is shown in FIG. The example of FIG. 7 is a case where audio is reproduced by a digital audio signal from a digital audio output device.

The digital audio output device 210 is a CD player, a DAT (Digital Audio Tape Recorder), or the like.
Stereo audio signals consisting of left and right channel audio signals 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.

The 16-bit digital audio signal of the serial data from the digital audio output device 210 is supplied to the serial / parallel converter 220, where the left / right channel digital audio signals are separated. Are converted into parallel data, and the 16-bit left and right digital audio signals as the parallel data are supplied to the left and right channel speaker devices 100L and 100R.

Although not shown, the serial / parallel converter 220 obtains a clock at a bit rate, and the clock at the bit rate is supplied to the decoder 70.

In this example, the loudspeaker devices 100L and 100R have a decoder 70 and a loudspeaker drive circuit 4 respectively.
0 and a speaker unit 110. The speaker unit 110 includes the electromagnetically coupled speaker unit described with reference to FIGS.

In the case of this example, the speaker device 10
In 0L and 100R, the decoder 70 generates a control signal, which will be described later, from the 16-bit left and right digital audio signals converted into parallel data from the serial / parallel converter 220 in the decoder 70. The primary coil 2 of the speaker unit 110 is supplied to the
4 is driven.

When the primary coil 24 is composed of a plurality of coils, a 16-bit digital audio signal is
In the case of a 2 'complement code as shown in FIG. 8, the MSB (most significant bit) is used as a sign bit, and as described above, and as shown in FIGS. Coil LA-LG, LO
~ LP. Then, the coil LA is made to correspond to the LSB (least significant bit), for example, two turns.
Coil LB, LC, LD, LE, LF, LG, LI, L
J, LK, LL, LM, LN, LO, LP, 15S
B, 14SB, 13SB, 12SB, 11SB, 10S
B, 9SB, 8SB, 7SB, 6SB, 5SB, 4S
B, 3SB, 2SB, 4 turns each,
The number of turns is twice as many as the number of turns of the coil corresponding to the next lower bit, such as 8 turns, 16 turns, and so on.

When the analog audio signal is non-linearly quantized and converted into a digital audio signal, the number of turns of the plurality of coils constituting the primary coil 24 is, as described above, a geometric series. It does not change in a linear manner, but changes in accordance with the nonlinear characteristics of the nonlinear quantization.

FIG. 10 shows an example of a portion of the decoder 70 and the speaker drive circuit 40 shown in FIG. 7, and the speaker drive circuit 40 includes 15 coils LA of the primary coil 24.
, And 15 coil drive circuits 40A to 40G and 40I to 40P corresponding to .about.LG, LI.about.LP.

Then, each coil drive circuit 40A
-40G and 40I-40P are respectively composed of four FETs 51-54 as switching elements and a primary coil 24.
Of the coils LA to LG and LI to LP are connected in bridge, and the constant current source 41 is connected in series.

Then, the FETs 51 and 53 are turned on,
When 52 and 54 are turned off, the current Ia of the constant current source 41 is applied to the coil corresponding to each bit (hereinafter referred to as the corresponding primary coil) in the positive direction among the plurality of coils of the primary coil. Flow, FETs 51 and 53 are off, F
When the ETs 52 and 54 are turned on, the constant current source 41
Is caused to flow in the negative direction to the corresponding primary coil.

Coil driving circuits 40A-40G, 40I-
The currents of the 40P constant current sources 41 are all set to the same current value as indicated by the current Ia. When all of the FETs 51 to 54 are turned on or off in the same coil drive circuit, no current flows through the corresponding primary coil.

The decoder 70 has fifteen control signal generation circuits corresponding to the fifteen coils LA to LG and LI to LP of the primary coil 24, ie, corresponding to 15 bits excluding the MSB of the digital audio signal. 70A to 70G, 70I
To 70P, and the respective control signal generation circuits 70A to 70P.
From 70G and 70I to 70P, the MSB of the digital audio signal converted into parallel data from the serial / parallel converter 220 and the control signal generation circuits 70A to 70A
0G, lower bits corresponding to 70I to 70P (LSB to
2SB), four control signals G1 to G4, which will be described later, are obtained, and the control signals G1 to G4 correspond to the FETs of the corresponding coil driving circuit of the speaker driving circuit 40.
It is supplied to the gates 51-54.

When the MSB of the input digital audio signal is 0 and the corresponding lower-order bit is 1, the four control signals G1 to G4 are the levels at which the control signals G1 and G3 turn on the FETs 51 and 53, and the control signal G2 , G4 are FETs 52, 5
4 is turned off, and the corresponding primary coil
The current Ia flows in the plus direction. On the other hand, when the MSB of the digital audio signal is 1 and the corresponding lower bit is 0, the control signals G1 and G3 are at a level for turning off the FETs 51 and 53, and the control signals G2 and G4 are at a level for turning on the FETs 52 and 54. The current Ia flows through the corresponding primary coil in the opposite negative direction.

When the MSB of the digital audio signal is 0,
When the corresponding lower bit is also 0 or when the MSB is 1
When the corresponding lower bit is also 1, the control signal G1
G4 becomes a level for turning off the FETs 51 to 54,
No current flows in the corresponding primary coil.

It should be noted that the control signals G1 to G4 correspond to the FETs 51 to
By turning on all 54, it is also possible to prevent current from flowing through the corresponding primary coil. In that case, a current always flows through the circuit, and a stable operation can be performed.

The driving force F of the vibration system of the electromagnetically coupled speaker is
As 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, F = B · L · 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 25 is proportional to the product of the signal current flowing through the primary coil and the number of turns of the primary coil.

In the above example, the primary coil 24
, The number of turns of each of the coils LA to LG and LI to LP is made proportional to the weight of each bit excluding the MSB of the input digital audio signal.
Corresponding to the coil in which the current Ia flows as a signal current among the five coils, the secondary coil 25C has the above-mentioned primary coil 24 in the direction corresponding to the value of the MSB of the digital audio signal. A secondary current having a current value proportional to the weight of the bit corresponding to the coil through which the current Ia flows is induced.

That is, a secondary current having a total sum of current values proportional to the weight of a bit corresponding to the coil of the primary coil 24 through which the current Ia flows flows through the secondary coil 25C. Thereby, the cone paper 29, which is a diaphragm to which the secondary coil unit 25 is fixed, vibrates in a direction corresponding to the value of the MSB of the input digital audio signal by an amount proportional to the digital data value of the one sample, In the speaker unit 110, sound is faithfully reproduced according to the input digital sound signal.

The coil driving circuits 40A to 40G, 4
The switching elements of 0I to 40P are not limited to FETs, and other elements that operate at high speed can be used.

In the above-described example, the number of turns of each of the coils LA to LG and LI to LP constituting the primary coil 24 is set to a number of turns in proportion to the weight of each bit excluding the MSB of the input digital audio signal. In the case of reproducing the difference in the weight of each bit of the input digital audio signal, the number of turns of each of the coils LA to LG and LI to LP is the same,
Corresponding coil drive circuits 40A to 40G, 40
By changing the current value of the constant current source of I-40P,
The difference in the weight of each bit of the input digital audio signal can be reproduced.

FIG. 11 shows an example of this case, in which fifteen coils LA to LG and LI to L constituting the primary coil 24 are shown.
P has the same number of turns, for example, 50 turns, and the constant current sources 4LA-41G, 41I-41P of the coil drive circuits 40A-40G, 40I-40P corresponding to the coils LA-LG, LI-LP. Current Ia-I
g, Ii to Ip are changed as described later. The rest is the same as the example of FIG.

As described above, the speaker unit 110
Is proportional to the secondary current i induced in the secondary coil, and the secondary current i is proportional to the product of the signal current flowing through the primary coil and the number of turns of the primary coil. I do.

Therefore, in this example, although omitted in FIG. 11, as shown in FIGS. 8 and 9, the current of the constant current source of the coil drive circuit corresponding to the coil LB corresponding to 15SB of the digital audio signal is used. Ib is set to twice the current Ia of the constant current source 41A of the coil drive circuit 40A corresponding to the coil LA corresponding to the LSB of the digital audio signal. That is, Ib = 2Ia.

Hereinafter, 14SB, 13 of the digital audio signal will be described.
Coil LC, LD, LE corresponding to SB, 12SB, ...
, Ic, I of the constant current source of the coil drive circuit corresponding to.
are twice as large as the currents Ib, Ic, Id,.

Therefore, as in the example of FIG. 10, in speaker unit 110, diaphragm 29 adjusts the weight of the bit corresponding to the primary coil through which the signal current flows in the direction corresponding to the value of the MSB of the digital audio signal. It vibrates by a proportional amount, and the sound is reproduced faithfully according to the input digital sound signal.

In the case where 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 drive coil as the primary coil can be made one. The primary coil in this case is attached to either the center pole portion 21a or the plate 22.

FIG. 12 shows an example in that case. However,
In this example, the input digital audio signal, that is, 1 as the parallel data from the serial / parallel converter 220
This is a case where a 6-bit digital audio signal is a natural binary code.

In this example, the primary coil 111 is composed of one coil, and currents Ia, Ib,.
, 61P are connected via switch circuits 62A, 62B,..., 62P, respectively, and the switch circuits 62A, 62B,. It is switched by the data of the corresponding bit of the signal.

That is, when a certain bit of the input digital audio signal is 1, the corresponding switch circuit is turned on, and the current of the corresponding constant current source flows through the primary coil 111. The current Ib of the constant current source 61B is twice the current Ia of the constant current source 61A. Hereinafter, the current of the constant current source corresponding to each bit of the digital audio signal corresponds to the next lower bit. It is twice the current of the constant current source.

Therefore, in this example, in the speaker unit 110, the diaphragm 29 vibrates in one direction by an amount proportional to the weight of each bit of the input digital audio signal, and the sound is reproduced faithfully to the input digital audio signal. Is done.

The number of primary coils 111 is not one,
It is also possible to provide two or more coils having the same number of turns, divide the current corresponding to each bit of the 16 bits into a corresponding number of groups, and flow the current of each group to one coil. . For example, a primary coil is constituted by one coil provided on the center pole portion 21a and one coil provided on the plate 22, and the digital signal is divided into upper 8 bits and lower 8 bits. ,
It is possible to adopt a configuration in which a group of currents corresponding to each of the two currents flows through the two coils.

Even when the input digital audio signal is a 2 'complement code, the coil drive circuits 40A to 40P as shown in FIG. 11 can be switched by the corresponding bit data of the digital audio signal. By doing so, the primary coil 111 can be reduced to one.

Further, by combining 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, the difference in the weight of each bit of the digital audio signal can be reproduced.

FIG. 13 shows an example in that case. However,
In this example, the input digital audio signal, that is, 1 as the parallel data from the serial / parallel converter 220
This is a case where a 6-bit digital audio signal is a natural binary code.

In this example, the primary coil is composed of four coils 111S, 111T, 111 having a turn ratio as described later.
U, 111V, and each coil 111S,
Driving blocks S, T, U, and V are provided for 111T, 111U, and 111V, and the driving blocks S, T, U, and V include currents Ia, Ib, and Ib, respectively.
The constant current sources Ic and Id are respectively connected to the corresponding coils 111S, 111T, 111U or 111V via switch circuits.

That is, in the drive block S, the constant current sources 61A, 61B, 61C, 61D are connected to the corresponding coils 111S via the switch circuits 62A, 62B, 62C, 62D, respectively. The current sources 61E, 61F, 61G, and 61H are respectively connected via switch circuits 62E, 62F, 62G, and 62H.
In the drive block U, the constant current sources 61I, 61J, 61K, and 61L are connected to the corresponding coil 111U via switch circuits 62I, 62J, 62K, and 62L, respectively. Then, the constant current sources 61M, 61N, 61O, 61P
Are the switch circuits 62M, 62N, 62O, 6
The switch circuits 62A, 62B,... 62N, 62 are connected to the corresponding coil 111V via the 2P.
O and 62P are switched by the data of the corresponding bit of the input digital audio signal.

The coils 111S, 111T, 111U, 1
Turns ratio of 11V is from 1: 16: 16 ^2: is 16 ^3. The constant current source 61A, 61B, 61C, the current Ia of 61D, Ib, Ic, Id ratio is 1: 2: ² 2: is 2 ^3. That, Ib = 2 · Ia, Ic = 2 2 · Ia, are Id = 2 ³ · Ia.

As described above, the speaker unit 110
Is proportional to the secondary current i induced in the secondary coil, and the secondary current i is proportional to the product of the signal current flowing through the primary coil and the number of turns of the primary coil. I do.

Therefore, in this example, when a certain bit of the digital audio signal becomes 1, the corresponding one of the switch circuits 62A, 62B... 62P is turned on, and the primary coil 111S, 111T, 111U or 1
When the current Ia, Ib, Ic or Id flows through 11 V, the ratio of the secondary current induced in the secondary coil matches the ratio of the weight of each bit of the digital audio signal.

Therefore, as in the example of FIG. 12, in the speaker unit 110, the diaphragm 29 is moved in one direction.
The audio signal is shifted by an amount proportional to the weight of each bit of the digital audio signal, and the audio is reproduced faithfully to the input digital audio signal.

In this example, the minimum number of turns 1
Primary coil 111S and primary coil 111 having the largest number of turns
The ratio of the number of turns to V can be made as small as 1:16 ³ = 1: 2 ¹² , and the ratio of the current value between the minimum current value Ia and the maximum current value Id can be reduced. , 1:
It can be significantly reduced and so 2 ^3.

Although not shown, the primary coil is composed of four coils having a turn ratio of 1: 2: 4: 8, and each of the coils is provided with a switch circuit. , The ratio of the current values is 1:16:16 ² : 16
³ , four constant current sources are connected, and the combination of the four constant current sources having the minimum current value and each coil is made to correspond to the LSB, 2SB, 3SB, and 4SB of the input digital audio signal, respectively. The combinations of the four constant current sources having the second smallest values and the coils correspond to the input digital audio signals of 5SB, 6SB, 7SB, and 8SB, respectively, and the four constant current sources having the second largest current values And the combination of each coil with 9SB, 10
The combinations of the four constant current sources having the maximum current values and the respective coils corresponding to SB, 11SB, and 12SB are used as the digital audio signals of 13SB, 14SB, 15SB, and M, respectively.
In this case, the ratio of the number of turns between the primary coil having the minimum number of turns and the primary coil having the maximum number of turns may be significantly reduced, such as 1: 8. it is possible to, the minimum ratio of the current value between the current value and the maximum current value of 1: 16 can be significantly reduced that so called ^3.

In this way, it is possible to reproduce low to high tones with flat frequency characteristics, and to reproduce audio directly from a digital audio signal without using a D / A converter or a power amplifier. Thus, a speaker device having a large maximum output can be realized.

FIG. 14 shows another example of 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 supplied to a chopper circuit 520, and the analog audio signal Ao shown in FIG.
As shown by c, the chopping is performed at a frequency higher than the audio frequency, that is, at a frequency fc exceeding 20 kHz which is the upper limit of the audio frequency.

Here, the chopping frequency fc is
It is desirable that the frequency be about twice as high as 20 kHz, for example, 40 kHz. In addition, the time width of the chopping period is sufficiently shorter than the chopping cycle Tc.

Then, the chopped analog audio signal Ac from the chopper circuit 520 is amplified by the power amplifier 530, and
0 is supplied to the primary coil 111. In this case, the speaker unit 110 has one primary coil 111. When the audio signal current is supplied to the primary coil 111, a secondary current is induced in the secondary coil, and the diaphragm vibrates.

As described above, the speaker unit 110, which is an electromagnetically coupled speaker, has an electromagnetic coupling force that induces a secondary current i in the secondary coil due to a signal current flowing through the primary coil 111, from several kHz to 1 kHz or less. Becomes smaller in the low frequency range.

However, according to the example of FIG. 14, the analog audio signal is intermittently transmitted at a frequency fc higher than the audible frequency and is supplied to the primary coil 111 of the speaker unit 110. Also, the signal current flowing through the primary coil 111 has a high frequency exceeding 20 kHz. Therefore, the speaker unit 110, which is an electromagnetically coupled speaker, has a flat frequency characteristic from a low band to a high band and can reproduce sound with good sound quality.

[0125]

As described above, according to the present invention, the secondary coil unit of the digitally driven electromagnetically coupled speaker unit is provided with the sub-diaphragm for reproducing the middle and high frequency range integrally. In addition, the mid-high range characteristics and the sound quality of the middle high range can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a structure of an example of a speaker unit used in an embodiment of a speaker device according to the present invention.

FIG. 2 is a diagram illustrating an example of a primary coil used in the speaker unit of FIG. 1;

FIG. 3 is a diagram illustrating another example of a primary coil used in the speaker unit of FIG. 1;

FIG. 4 is a diagram showing an example of an integrated part of a secondary coil and a sub diaphragm used in the speaker unit of FIG. 1;

FIG. 5 is a diagram showing an example of an auxiliary bobbin used in the speaker unit of FIG. 1;

6 is a view showing a state in which the integrated component of FIG. 4 is attached to the auxiliary bobbin of the example of FIG. 5;

FIG. 7 is a diagram showing an example of a sound reproduction system using an example of a speaker device according to the present invention.

FIG. 8 is a diagram for explaining an input digital signal.

FIG. 9 is a diagram for explaining the driving principle of the speaker device according to the present invention.

FIG. 10 is a circuit diagram showing a specific example of the partial circuit of FIG. 7;

FIG. 11 is a diagram showing an example of a sound reproduction system using another example of the speaker device according to the present invention.

FIG. 12 is a diagram showing an example of a sound reproduction system using another example of the speaker device according to the present invention.

FIG. 13 is a diagram showing an example of a sound reproduction system using another example of the speaker device according to the present invention.

FIG. 14 is a diagram showing an example of a sound reproduction system using another example of the speaker device according to the present invention.

FIG. 15 is a diagram for explaining the example of FIG. 14;

FIG. 16 is a sectional view of a structure of a conventional speaker device.

FIG. 17 is a diagram showing an example of a secondary coil unit of the conventional speaker device of FIG.

[Explanation of symbols]

21: first magnetic yoke, 21a: center pole portion,
21b: Flange portion, 22: Second magnetic yoke (plate), 23: Magnet, 24: Drive coil (primary coil), 25: Secondary coil, 26: Sub diaphragm, 27: Integrated component, 28: Auxiliary coil, 29 ... cone paper as an example of main diaphragm, 29e ... edge, 30 ... damper, 31 ...
Speaker frame, 32 gasket, 33 cap, 34 through hole, 35 magnet guide, 37a-
37g and 37i-37p ... Lead wire pairs, 38a-3
8g and 38i to 38p: input terminal, GP: magnetic air gap

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H04S 5/02 H04S 5/02 B

Claims (6)

[Claims] A primary coil fixed to a portion near a gap in a magnetic circuit; and a short coil arranged in the gap and inducing a secondary current corresponding to a current flowing through the primary coil. A secondary coil configured; a main diaphragm attached to a secondary coil unit on which the secondary coil is formed and fixed to a speaker frame via an edge portion; and the secondary coil unit as an integral part And a sub-diaphragm attached to the speaker device. 2. The secondary coil has a cylindrical shape made of a non-magnetic material and a conductive material, and the secondary coil unit is constituted by omitting the coil bobbin. The speaker device according to claim 1, wherein the speaker device is formed as an integral part with the secondary coil having the shape. 3. The speaker device according to claim 1, wherein a signal that changes at a rate higher than an audible frequency is supplied to the primary coil. 4. The speaker device according to claim 1, further comprising a speaker driving circuit for driving said primary coil by a digital audio signal, wherein said primary coil has a different number of turns from each other, and And the speaker drive circuit has a number of drive sources corresponding to the number of bits of the digital audio signal, for supplying a signal current to each coil constituting the primary coil. A loudspeaker device, the respective driving sources of which are controlled by different bits of the digital audio signal. 5. The speaker device according to claim 3, wherein the primary coil is formed of one coil having one or more turns, and the speaker driving circuit is configured to control the one coil so that signals of different current values are supplied to the one coil. A loudspeaker device having a number of drive sources for supplying current corresponding to the number of bits of the digital audio signal, each of which is controlled by a different bit of the digital audio signal. 6. The speaker device according to claim 1, wherein the primary coil includes a plurality of coils having different numbers of windings, and the speaker driving circuit is different from each other for each of the plurality of coils. A speaker device, wherein a plurality of drive sources for supplying a signal current having a current value are connected, and each of the plurality of drive sources is controlled by a different bit of the digital audio signal.