JP3147662B2 - Sound reproduction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound reproducing apparatus for detecting a sound reproduced from a speaker used in various kinds of audio equipment with a microphone and correcting the sound reproduced from the speaker based on the detection signal.

[0002]

2. Description of the Related Art A conventional sound reproducing apparatus of this type will be described with reference to the drawings.

FIG. 86 is a block diagram showing the configuration of a conventional sound reproducing apparatus using a feedback circuit. A signal is input from an input terminal 50, passes through a subtracter 51, and passes through a power amplifier 52.
, And a signal is applied to the speaker 53. An acoustic signal output from the speaker 53 is detected by a microphone 54, and the signal is detected by a microphone amplifier 55
, And the output signal is connected to the subtractor 51 through the filter 56.

FIG. 87 is a block diagram showing a configuration in which the speaker 53 of the sound reproducing apparatus shown in FIG. 86 is incorporated in a speaker box 58 using a passive radiator 57. The obtained signal is amplified by a power amplifier 52 through a subtracter 51, and an output signal of the power amplifier 52 is reproduced by a speaker 53 coupled inside a speaker box 58. A closed acoustic space 58A is provided on the rear surface of the speaker 53, and a closed acoustic space 58B is also provided on the front surface. The passive radiator 57 connected to the closed space 58B and the opening of the speaker box 58 provides a speaker box. 58
An acoustic output signal radiated from the passive radiator 57 is detected by the microphone 54, and the detected signal is amplified by the microphone amplifier 55, and the input terminal 50 is connected through the filter 56. In this configuration, a negative feedback loop is formed by connecting to the negative input terminal of the subtractor 51.

[0005]

However, in the above-mentioned conventional configuration, the phase difference between the electric signal input to the speaker 53 and the acoustic signal radiated from the speaker 53 is disturbed as shown in FIG. Negative feedback is provided around °, but positive feedback is provided at all around + 180 ° or -180 °, which causes a problem that a sufficiently unstable feedback system cannot provide sufficient negative feedback.

Further, when the band is limited by the filter 56 in order to secure a transmission margin, there is a problem that the sound output is limited to only a limited frequency band and the sound output cannot be sufficiently improved. .

In the conventional configuration using the passive radiator 57 shown in FIG. 87, the phase difference between the electric signal input to the speaker 53 and the acoustic output signal radiated from the passive radiator 57 is + 180 ° or more. -180 °
Therefore, stable negative feedback cannot be obtained, and the acoustic signal input to the microphone 54 also detects extraneous sounds other than the acoustic signal radiated from the passive radiator 57. Signal to noise ratio (S /
N ratio) could not be secured, and high-frequency components were removed through the filter 56 to try to secure the S / N ratio. However, there was a problem that a sufficient S / N ratio could not be obtained.

An object of the present invention is to solve such a conventional problem and to provide an audio reproducing apparatus capable of exhibiting stable performance.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a sound reproducing apparatus according to the present invention comprises a subtracter connected to an input terminal, a power amplifier for amplifying an output signal of the subtractor, and a power amplifier for the power amplifier. A speaker for reproducing the output signal,
A microphone for detecting an acoustic output signal radiated from the speaker, a microphone amplifier for amplifying the acoustic output signal detected by the microphone, and adding or subtracting an output signal of the microphone amplifier and an input signal of the power amplifier. It comprises an adder / subtractor, and an output signal of the adder / subtractor is connected to the subtractor to constitute a feedback circuit.

In a sound reproducing apparatus using a speaker box in which a passive radiator is incorporated, the sound reproducing apparatus reproduces an output signal of a power amplifier in a closed acoustic space on an upper surface of a magnetic circuit of a speaker or a rear surface of the speaker, or a passive radiator in front of the speaker. A microphone is arranged in a closed acoustic space between the microphones, an output signal of the microphone is added to and subtracted from an input signal, and the signal is further subtracted from the input signal.

[0011]

According to this configuration, the phase difference between the electric signal input to the speaker and the sound output signal radiated from the speaker is added or subtracted by the adder / subtractor in accordance with the difference, so that the phase difference is changed. Oscillation (howling) due to positive feedback is less likely to occur, and feedback can be stably applied over a wide frequency range.

In a sound reproducing apparatus using a speaker box incorporating a passive radiator, an acoustic signal radiated from a speaker is electrically controlled with respect to a passive radiator air-coupled to an acoustic space to provide acoustic characteristics. Can be improved.

[0013]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the structure of a sound reproducing apparatus according to a first embodiment of the present invention. In FIG. 1, a signal inputted from an input terminal 1 is inputted to a subtracter 2 and The output signal is input to the power amplifier 3, a speaker 4 is connected to the output side of the power amplifier 3, an acoustic output is emitted from the speaker 4, and the acoustic output signal is detected by the microphone 5.

The detected signal is amplified by a microphone amplifier 6, and the output signal of the subtractor 2 is subtracted or added by an adder / subtractor 7 from the output signal. A feedback circuit is formed by inputting the output signal of the adder / subtractor 7 to the subtractor 2. The adder / subtracter 7 is used as an adder when the sound output signal of the speaker 4 is in the normal phase, and is used as a subtractor when the sound output signal of the speaker 4 is in the opposite phase.

The transfer function of the circuit constituting the sound reproducing apparatus according to the first embodiment can be expressed as follows: V _out / V _in = A / (2 + A · T (S)) Here, A: amplification factor of the power amplifier 3, T (S): (including microphone transmission characteristic) transfer function of the loudspeaker 4, V _in: input voltage, V _out: the output voltage of the power amplifier 3.

[0017] In this context, if is sufficiently large _{A V out / V in ≒ 1} / T (S) , and becomes an inverse characteristic of the transfer characteristic of the speaker 4. However, in practice, oscillation (howling) occurs, so the size of A is limited. In general, when | 2 + AT (S) |> 1, negative feedback | 2 + AT (S) | <1 The time is positive feedback.

[0018] Clearly when the block diagram shown in FIG. 87 as a conventional example expressed in the same manner as described _{above, V out / V in = A} / (1 + A · T (S)) becomes, which when compared with the transfer function of the present invention It can be seen that the amount of feedback can be increased as compared with the conventional case.

FIG. 28 shows the frequency characteristics of the speaker 4 according to this embodiment, and FIG. 29 shows the output voltage versus frequency characteristics of the power amplifier 3 at this time.

The position of the microphone 5 in this embodiment is indicated by reference numeral 5e in FIG.
As shown in the position of ス ピ ー カ, the speaker 4 is installed above the center of the center pole of the lower plate 35 of the speaker 4, and has a mid-range characteristic (700 Hz to 1.
5 KHz) has been improved.

(Embodiment 2) A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing a configuration of a sound reproducing apparatus according to a second embodiment, in which a signal from an output terminal of a power amplifier 3 is connected to an input signal of an adder / subtractor 7. Other configurations are the same as those in the first embodiment.

Further, the transfer function of this circuit, it is possible to increase the feedback amount than _{V out / V in = A /} (1 + A + A · T (S)) , and the similar to the first embodiment conventional Things.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a block diagram showing a configuration of a sound reproducing apparatus according to a third embodiment. In addition to the configuration of the first embodiment, a filter 8 is provided between a microphone amplifier 6 and an adder / subtractor 7. The other configuration is the same as that of the first embodiment.

FIG. 30 shows the characteristics of the filter 8, and the higher the frequency, the higher the amplification. The phase characteristic of this filter has a phase lead of about 60 ° at 1.5 KHz.

In general, the phase characteristics of a loudspeaker lag from the frequency band exceeding the piston motion range (about 800 Hz) toward -180 ° as shown in FIG. 30, and the phase characteristics in the split resonance region are disturbed. However, edge resonance also occurs near the highest frequency of the piston motion, and since there is a large variation depending on the speaker, the amplitude and phase may become unstable when the feedback is performed. Therefore, the filter 8 having the above-described phase lead characteristic is inserted on the output side of the microphone amplifier 6 to secure a phase margin.

However, since the frequency characteristics also increase toward higher frequencies, a diagram showing a location where acoustically the frequency characteristics of the speaker gradually decrease as the frequencies increase, for example, a microphone arrangement position which will be described in detail later. Reference numeral 5e of 27,
By installing the microphones 5 at the positions 5f, 5g, and 5h and correcting the phase with the filter 8 as described above, it is possible to expand the band to which feedback can be stably applied.

(Embodiment 4) Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.

FIG. 4 is a block diagram showing the configuration of a sound reproducing apparatus according to a fourth embodiment. In addition to the configuration of the second embodiment, a filter 8 is inserted between a microphone amplifier 6 and an adder / subtractor 7. The other configuration is the same as that of the second embodiment.

In the present embodiment, the filter 8
As in the third embodiment, the stability of the feedback system can be improved, and a detailed description thereof will be omitted.

Embodiment 5 Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings.

FIG. 5 is a block diagram showing the structure of a sound reproducing apparatus according to the fifth embodiment.
A high-pass filter 11 and a second adder / subtractor 10 are added to the configuration of the embodiment, and the output signal of the microphone amplifier 6 and the input signal of the power amplifier 3 are subjected to the second addition / subtraction through the high-pass filter 11. The output signal is input to the adder 10 and connected so that the output signal added / subtracted by the second adder / subtractor 10 is fed back to the subtractor 9.

The transfer function of this circuit is represented by a first adder / subtracter 7
The subtractor, the second adder-subtracter 10 and an adder, when the transfer characteristic of the high-pass filter 11 and _{T (F) V out / V} in = A / (2 + A · T (S) + T (F) - A ・ T (S) ・
T (F)), and from this transfer function, if T (F) is a first-order high-pass filter and is a frequency band that blocks a signal, T (F)
(F) ≒ 0, and the transfer function is V _out / V _in ≒ A / (2 + AT (S)), which is the same transfer function as in the first embodiment. Further T
When (F) is a frequency band that passes a signal, T (F) ≒
It becomes 1 and the transfer function becomes V _out / V _in ≒ A / 3.

That is, in this circuit configuration, the same feedback as in the first embodiment is applied in the frequency cut-off band of T (F), and the transfer characteristic T (S) of the speaker 4 when T (F) is the pass frequency band. Irrespective of this, the amplification degree becomes constant.

In this circuit, for example, when the split resonance of the speaker 4 exists in a high frequency range and the phase rotation is so severe that howling cannot be avoided, the band limited by T (F) is further fed back in parallel to transmit the signal from the speaker 4. Howling can be prevented regardless of the characteristics.

(Embodiment 6) Hereinafter, a sixth embodiment of the present invention will be described with reference to the drawings.

FIG. 6 is a block diagram showing the configuration of a sound reproducing apparatus according to the sixth embodiment. The difference from the fifth embodiment is that one end of the first adder / subtractor 7 is connected to the output terminal of the power amplifier 3. That is the point.

This circuit also uses the first adder / subtractor 7 as a subtractor and the second adder / subtractor 10 as an adder, as in the fifth embodiment, and the transfer function of the high-pass filter 11 is represented by T (F). Then, the transfer function is: V _out / V _in = A / (1 + A + AT (S) + AT (F) -AT
(S) · T (F) ) and can be represented, (in the case of _{F) ≒ 0, V out /} V in = A / (1 + A + A · T (S) T) becomes, T (F) of ≒ 1 case is that eliminates the dependence of _{V out / V in = a /} (1 + 2A) , and the transfer characteristic of the pass band only speaker 4 T (F) with respect to the example 2 T (S).

Embodiment 7 Hereinafter, a seventh embodiment of the present invention will be described with reference to the drawings.

FIG. 7 is a block diagram showing a configuration of a sound reproducing apparatus according to a seventh embodiment.
The filter 8 used in the third embodiment is inserted between the first adder / subtracter 7 and the parallel circuit of the high-pass filter 11, and the rest is the same as the fifth embodiment.

In the present embodiment, the stability of the feedback system can be improved by the filter 8 in the same manner as in the third embodiment, and a detailed description thereof will be omitted.

Embodiment 8 Hereinafter, an eighth embodiment of the present invention will be described with reference to the drawings.

FIG. 8 is a block diagram showing the configuration of the sound reproducing apparatus according to the eighth embodiment, in which the microphone amplifier 6 is connected between the first adder / subtractor 7 and the parallel circuit of the high-pass filter 11 according to the eighth embodiment. The third embodiment has the same configuration as the sixth embodiment except that the filter 8 used in the third embodiment is inserted.

In this embodiment, the stability of the feedback system can be improved by the filter 8 in the same manner as in the third embodiment, and a detailed description thereof will be omitted.

(Embodiment 9) Hereinafter, a ninth embodiment of the present invention will be described with reference to the drawings.

FIG. 9 is a block diagram showing the configuration of a sound reproducing apparatus according to a ninth embodiment. A first subtractor 12 and a second subtracter 13 are connected in series to an input terminal 1 and 1
The input terminal of the power amplifier 3 is connected to the minus terminal of the subtractor 12, and the output of the microphone amplifier 6 is connected to the minus terminal of the second subtractor 13. 3, the output signal of the microphone amplifier 6 is subtracted from the output signal of the first subtractor 12 by the second subtractor 13, and the output signal is connected as the input signal of the power amplifier 3. It is configured.

The transfer function of this circuit is for _{V out / V in = A /} (2 + A · T (S)) , and the same transmission characteristic as in Example 1 to obtain, the transfer characteristic described above in Example 1 and the detailed description is omitted.

(Embodiment 10) Hereinafter, a tenth embodiment of the present invention will be described with reference to the drawings.

FIG. 10 is a block diagram showing the structure of a sound reproducing apparatus according to the tenth embodiment. The present embodiment is different from the ninth embodiment in that the first subtractor 12 connected to the input terminal 1 is connected. The other point is that the output of the power amplifier 3 is connected to the minus terminal of the power amplifier 3, and the other configuration is the same as that of the ninth embodiment. The first subtracter 12 subtracts the output signal of the power amplifier 3 from the input signal. The output signal of the microphone amplifier 6 is subtracted from the output signal of the first subtractor 12 by the second subtractor 13, and the output signal is connected as the input signal of the power amplifier 3.

The transfer function of this circuit is for _{V out / V in = A /} (1 + A + A · T (S)) , and the same transmission characteristic as in Example 2 to obtain, the transfer characteristic described above in Example 2 and the detailed description is omitted.

Embodiment 11 Hereinafter, an eleventh embodiment of the present invention will be described with reference to the drawings.

FIG. 11 is a block diagram showing the configuration of the sound reproducing apparatus according to the eleventh embodiment. In this embodiment, the output of the microphone amplifier 6 and the second subtractor 13 are added to the configuration of the ninth embodiment. This is a configuration in which the filter 8 used in the third embodiment is inserted between a minus input terminal and the other configuration is the same as that of the ninth embodiment.

In this embodiment, the stability of the feedback system can be improved by the filter 8 in the same manner as in the third embodiment, and a detailed description thereof will be omitted.

Embodiment 12 Hereinafter, a twelfth embodiment of the present invention will be described with reference to the drawings.

FIG. 12 is a block diagram showing a configuration of a sound reproducing apparatus according to a twelfth embodiment. In this embodiment, in addition to the configuration of the tenth embodiment, the negative input of the microphone amplifier 6 and the second subtractor 13 is provided. This is a configuration in which the filter 8 used in the third embodiment is inserted between the terminal and the terminal. The other configuration is the same as that of the tenth embodiment.

In this embodiment, the stability of the feedback system can be improved by the filter 8 in the same manner as in the third embodiment, and a detailed description thereof will be omitted.

Embodiment 13 Hereinafter, a thirteenth embodiment of the present invention will be described with reference to the drawings.

FIG. 13 is a block diagram showing a configuration of a sound reproducing apparatus according to a thirteenth embodiment. In this embodiment, the microphone amplifier 6 and the minus terminal of the second subtractor 13 are added to the configuration of the ninth embodiment. And an output terminal of the second subtractor 13 is branched and connected to the input terminal of the adder / subtractor 7, and the output signal of the microphone amplifier 6 and the second The output signal of the subtractor 13 is subjected to addition and subtraction processing by the adder / subtractor 7, the output signal is connected to the minus input terminal of the second subtractor 13, and the first subtractor 12 is connected to the stage before the second subtractor 13. They are connected in series, and the output signal of the second subtractor 13 is input to the minus input terminal of the first subtractor 12.

The transfer function of this circuit is as follows: V _out / V _in = A / (3 + AT · (S)) From this, the present embodiment uses the feedback amount further than the circuit described in the first embodiment. Can be increased.

Embodiment 14 Hereinafter, a fourteenth embodiment of the present invention will be described with reference to the drawings.

FIG. 14 is a block diagram showing the structure of a sound reproducing apparatus according to a fourteenth embodiment. This embodiment is different from the thirteenth embodiment in that the input of the adder / subtractor 7 and the first subtractor 1 are different.
The output signal of the power amplifier 3 is connected to the negative input terminal 2 of the second embodiment, and the other configuration is the same as that of the thirteenth embodiment.

The transfer function of this circuit is as follows: V _out / V _in = A / (2 + A + A · T (S)). From this, using this embodiment, the amount of feedback is more than that of the circuit described in the second embodiment. Can be increased.

Embodiment 15 Hereinafter, a fifteenth embodiment of the present invention will be described with reference to the drawings.

FIG. 15 is a block diagram showing the structure of a sound reproducing apparatus according to the fifteenth embodiment. The filter 8 used in Example 3 in between
Are inserted, and the rest is the same as the thirteenth embodiment.

This embodiment can improve the stability of the feedback system by using the filter 8 as in the case of the third embodiment, and a detailed description thereof will be omitted.

Embodiment 16 Hereinafter, a sixteenth embodiment of the present invention will be described with reference to the drawings.

FIG. 16 is a block diagram showing a configuration of a sound reproducing apparatus according to a sixteenth embodiment. In this embodiment, in addition to the configuration of the fourteenth embodiment, the output of the microphone amplifier 6 and the input of the adder / subtractor 7 are used. The filter 8 used in Example 3 in between
Are inserted, and the rest is the same as the fourteenth embodiment. This embodiment can improve the stability of the feedback system in the same manner as the third embodiment by using the configuration using the filter 8, and a detailed description thereof is omitted.

Embodiment 17 Hereinafter, a seventeenth embodiment of the present invention will be described with reference to the drawings.

FIG. 17 is a block diagram showing the configuration of the sound reproducing apparatus according to the seventeenth embodiment. In the present embodiment, the subtractor 2 provided in the input section of the first embodiment is used as a second subtractor 13, and the input terminal of the second subtractor 13 is further connected to the first subtractor 12, and Input terminal 1 for signal input is connected to the input terminal, and power amplifier 3 is connected to the negative input terminal.
Is input.

With this configuration, the output signal of the microphone amplifier 6 and the input signal of the power amplifier 3 are added or subtracted by the adder / subtractor 7, and the output signal of the adder / subtractor 7 is subtracted from the output signal of the first subtractor 12. And the output signal of the power amplifier 3 is subtracted from the input signal by the first subtractor 12. The transfer function of this circuit is as follows: V _out / V _in = A / (2 + A + A · T (S)), and this transfer characteristic is the same as that of the fourteenth embodiment, and a detailed description thereof will be omitted.

Embodiment 18 Hereinafter, an eighteenth embodiment of the present invention will be described with reference to the drawings.

FIG. 18 is a block diagram showing the configuration of the sound reproducing apparatus according to the eighteenth embodiment. In the present embodiment, the subtractor 2 provided in the input section of the second embodiment is used as a second subtractor 13, and an input terminal of the second subtractor 13 is further connected to a first subtractor 12, and The input terminal 1 for signal input is connected to the input terminal, and the output signal of the second subtractor 13 is input to the minus input terminal.

With this configuration, the output signal of the power amplifier 3 and the output signal of the microphone amplifier 6 are added or subtracted by the adder / subtractor 7, and the output signal of the adder / subtractor 7 is subtracted from the output signal of the first subtractor 12. Further, the input signal of the power amplifier 3 is subtracted from the input signal by the first subtractor 12, and the transfer function of this circuit is as follows: V _out / V _in = A / (2 + A + A · T ( S)).

The transfer characteristics are the same as those of the fourteenth embodiment, and the detailed description is omitted.

(Embodiment 19) Hereinafter, a nineteenth embodiment of the present invention will be described with reference to the drawings.

FIG. 19 is a block diagram showing a configuration of a sound reproducing apparatus according to a nineteenth embodiment. In this embodiment, in addition to the configuration of the seventeenth embodiment, the output of the microphone amplifier 6 and the input of the adder / subtractor 7 are added. The filter 8 used in Example 3 in between
Are inserted, and the other configuration is the same as that of the seventeenth embodiment.

This embodiment can improve the stability of the feedback system similarly to the third embodiment by employing the configuration using the filter 8, and a detailed description thereof will be omitted.

(Embodiment 20) Hereinafter, a twentieth embodiment of the present invention will be described with reference to the drawings.

FIG. 20 is a block diagram showing the configuration of a sound reproducing apparatus according to a twentieth embodiment. In this embodiment, in addition to the configuration of the eighteenth embodiment, the output of the microphone amplifier 6 and the input of the adder / subtractor 7 are connected. The filter 8 used in Example 3 in between
Are inserted, and the other configuration is the same as that of the eighteenth embodiment.

This embodiment can improve the stability of the feedback system similarly to the third embodiment by employing the configuration using the filter 8, and a detailed description thereof will be omitted.

Embodiment 21 Hereinafter, a twenty-first embodiment of the present invention will be described with reference to the drawings.

FIGS. 21 and 22 are block diagrams showing the structure of the sound reproducing apparatus according to the twenty-first embodiment.

FIG. 21 is a basic block diagram showing a case where a plurality of speakers and microphones are used and a single power amplifier 3 is used to perform acoustic feedback. Usually, speakers 4a, 4b, and 4c are used. Filters 14a, 14b, 14c and feedback circuit 15
The characteristics of the filters 16a, 16b, and 16c connected to the outputs of a, 15b, and 15c, respectively, are used.

The feedback circuits 15a, 15b,
Reference numeral 15c can be used as long as it has a circuit configuration in which the input of the power amplifier 3 and the output (or filter output) of the microphone amplifier 6 are added or subtracted in the first to twentieth embodiments. .

FIG. 22 shows the circuit configuration shown in FIG. 21 more specifically. A two-way loudspeaker system is constructed, and a low-pass circuit is provided by the coil 18 and a high-pass circuit is provided by the capacitor 19. And are connected to the bass speaker 4d and the treble speaker 4e, respectively. After the outputs of the microphones 5a and 5b are amplified by the microphone amplifiers 6a and 6b, the adders / subtractors 7a and 5b are amplified.
At 7b, the output signals of the subtracters 2a and 2b connected to the inputs are added and subtracted and connected to the minus input terminals of the subtracters 2a and 2b.

A filter 1 is applied to the outputs of the subtracters 2a and 2b.
After passing through 6e and 16d, they are added and input to the power amplifier 3. At this time, the filters 16e and 16d have the same characteristics as the output filter of the power amplifier 3 to suppress the interference between the speakers 4d and 4e of the microphones 5a and 5b.

With this configuration, it is possible to feed back the multi-way speaker system.

Embodiment 22 Hereinafter, a twenty-second embodiment of the present invention will be described with reference to the drawings.

FIGS. 23 and 24 are block diagrams showing the structure of a sound reproducing apparatus according to the twenty-second embodiment. FIG.
Shows the basic configuration of the present embodiment, and the speaker 4
The same number of microphones 5a to 5c as the number of microphones a to 4c (three in this embodiment)
The configuration is such that a filter is provided for the outputs of a to 5c to perform an addition / subtraction process, and then a feedback circuit 20 is provided to feed back to one subtractor.

FIG. 24 is a circuit showing this more specifically, in which the coil 18 and the capacitor 1 are connected to the output of the power amplifier 3.
9 are connected to the bass speaker 4d and the treble speaker 4e, respectively. The sound output is detected by the microphones 5a and 5b, and the microphone amplifiers 6a and 6b are detected.
b, and then subtracted through filters 8a and 8b.
And the respective signals are added and subtracted, and the output is connected to the minus terminal of the subtractor 2.

In this circuit configuration, all the configurations of the feedback circuits of the first to twentieth embodiments can be used, and the number of parts can be relatively smaller than that of the twenty-first embodiment. Can be.

Embodiment 23 Hereinafter, a twenty-third embodiment of the present invention will be described with reference to the drawings.

FIG. 25 is a block diagram showing the structure of the sound reproducing apparatus according to the twenty-third embodiment. This embodiment has a configuration in which a feedback circuit and a voltage controlled amplifier are used in an audio reproducing apparatus having a sound quality adjusting function. When the dynamic range of the system is restricted, for example, for a vehicle-mounted audio system or a hall acoustic system. It is the most suitable for the sound reproducing device.

As shown in FIG. 25, the signal input from the input terminal 1 passes through the voltage control amplifier 21, passes through the sound quality adjustment filter 22 (for example, a graphic equalizer), passes through the feedback circuit 23, and enters the power amplifier 3. Is done.
It is to be noted that the feedback circuit 23 can use any circuit that performs the addition / subtraction processing of the input signal of the power amplifier 3 and the output (or the filter output) of the microphone amplifier 6 in the first to 22th embodiments. It is.

In general, when acoustic feedback is applied or the frequency characteristic is changed by a sound quality adjustment filter, the dynamic range may be insufficient at a high level and clipping may occur at a high input level. In this embodiment, in order to solve this problem, the input voltage of the power amplifier 3 is detected by the level detector 24 to detect a voltage at which the output of the power amplifier 3 is not clipped, and the voltage higher than the detected voltage is detected by the AC / DC converter 25. To the voltage-controlled amplifier 2
The operation of decreasing the degree of amplification of 1 is performed.

By using the circuit of this embodiment having the above-described configuration, the clipping of the power amplifier 3 can be minimized regardless of the state of the sound quality adjustment filter 22 and the state of the feedback system. Things.

Embodiment 24 Hereinafter, a twenty-fourth embodiment of the present invention will be described with reference to the drawings.

FIG. 26 shows the configuration of the sound reproducing apparatus according to the twenty-fourth embodiment.
In the case where the configuration of the power amplifier 3 used in the twenty-third embodiment is different, that is, in a vehicle-mounted audio system, the power amplifier 26 is BTL (balanced, transformerless) connected, and is connected between its output terminal and ground. When a DC voltage of about half the power supply (battery) voltage is applied, only a DC component is extracted from the output of the power amplifier 26 and used as a power supply for the microphone 27.

When the power supply voltage is, for example, 14 V, the BT
An output terminal (positive output, negative output) of the power amplifier 26 connected to L is applied with a DC voltage of about 7 V between the output terminal and the ground, and AC signals oscillate in opposite phases with respect to the voltage. By adding these two signals by the resistors 28 and 29, AC components having phases opposite to each other are removed, and only a DC component (about 7 V) can be extracted. The capacitor 30 forms a low-pass filter with the resistors 28 and 29,
The DC voltage is stabilized.

In general, an electret condenser microphone is used as the microphone 27, and a field effect transistor is built in the microphone capsule. A resistor 31 is a bias resistor of the field effect transistor. Is taken out.

In general, when this sound reproducing apparatus is used in a vehicle, the connection cord of the microphone 27 uses a shielded wire. However, with the configuration of the present embodiment, the output resistance of the microphone 27 can be reduced. Is hardly affected by noise even with a single wire.

(Example 25) The following Examples 25 to 30
The embodiment described in the above describes a case where the arrangement of the microphones described in the above embodiments 1 to 24 is changed, and a twenty-fifth embodiment of the present invention will be described with reference to the drawings.

FIG. 27 shows a speaker of a sound reproducing apparatus according to the twenty-fifth embodiment. A microphone 5d for detecting a sound output signal is arranged on the front surface of a dust cap 34 connected to the center of a diaphragm 33. It is configured.

By arranging the microphone 5d in this portion, most of the frequency characteristics of the speaker can be detected.

Embodiment 26 Hereinafter, a twenty-sixth embodiment of the present invention will be described with reference to the drawings.

FIG. 27 shows a speaker of a sound reproducing apparatus according to the twenty-sixth embodiment, in which a microphone 5e for detecting a sound output signal is arranged on a center pole of a lower plate 35 constituting a magnetic circuit. Things.

By arranging the microphone 5e in this portion, a signal from the low frequency range to the limit value of the piston motion is detected, and the high frequency component thereafter is attenuated.

Embodiment 27 Hereinafter, a twenty-seventh embodiment of the present invention will be described with reference to the drawings.

FIG. 27 shows a speaker of the sound reproducing apparatus according to the twenty-seventh embodiment, in which a microphone 5f for detecting a sound output signal is arranged below the center hole of the lower plate 35.

By arranging the microphone 5f in this portion, the resonance (peak) of the center hole of the lower plate 35 appears in the high band as in the case of the twenty-sixth embodiment.

Embodiment 28 Hereinafter, a twenty-eighth embodiment of the present invention will be described with reference to the drawings.

FIG. 27 shows a speaker of a sound reproducing apparatus according to the twenty-eighth embodiment. A microphone 5g for detecting an acoustic output signal is arranged between a center pole of a lower plate 35 and a magnet 36 constituting a magnetic circuit. The configuration is such that:

When the microphone 5g is arranged in this portion, almost the same characteristics as those of the twenty-sixth embodiment can be obtained.

(Embodiment 29) Hereinafter, a twenty-ninth embodiment of the present invention will be described with reference to the drawings.

FIG. 27 shows a speaker of a sound reproducing apparatus according to the twenty-ninth embodiment. A microphone 5h for detecting a sound output signal is connected to the lower surface of a suspension 38 supporting a voice coil 40 and a frame 39 (or an upper plate 37). ).

The characteristic in the case where the microphone 5h is arranged in this portion is such that the high frequency of Example 25 is attenuated gently.

(Embodiment 30) Hereinafter, a thirtieth embodiment of the present invention will be described with reference to the drawings.

FIG. 27 shows a speaker of a sound reproducing apparatus according to the thirtieth embodiment, in which a microphone 5i for detecting a sound output signal is arranged between the diaphragm 33 and the frame 39.

When the microphone 5i is arranged in this portion, the characteristics substantially similar to those of the twenty-fifth embodiment can be obtained.

Embodiment 31 Hereinafter, a thirty-first embodiment of the present invention will be described with reference to the drawings.

FIG. 31 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment. In FIG. 31, 1 is an input terminal, 2 is a subtractor, 3 is a power amplifier, 5 is a microphone, 6 is a microphone amplifier, 7 Is an adder / subtractor,
The feedback circuit configured as described above is the same as in the first embodiment.

Reference numeral 41 denotes a closed space 41 communicating in the front-rear direction.
A and 41B are formed in the speaker box. The speaker box 41 has a closed space 41A on the rear room side.
, A passive radiator 43 is connected to the closed space 41B on the front room side, and the passive radiator 43 is driven by the speaker 42 via the closed space 41B.
Are driven to perform sound reproduction.

FIG. 32 is a half sectional view showing a speaker 42 connected to the speaker box 41. The microphone 5 is mounted on the center upper surface of the magnetic circuit 42A of the speaker 42.
And the voice coil 42B and the dust cap 42
A sound output signal generated in a space surrounded by C is detected,
Feedback is applied using the detected sound output signal.

The sound reproducing apparatus according to the present embodiment having the above-described configuration converts the input signal amplified by the power amplifier 3 through the subtractor 2 from the input terminal 1 as shown in FIG.
The sound is reproduced by the speaker 42 indicated by the symbol, and the acoustic output signal radiated from the speaker 42 is detected by the microphone 5,
After the output signal of the microphone 5 is amplified by the microphone amplifier 6, the output signal of the microphone amplifier 6 and the output signal of the subtractor 2 connected to the input terminal 1 are subjected to addition / subtraction (addition or subtraction) processing by the addition / subtraction unit 7. This is configured to be connected to the negative input terminal of the subtractor 2.

The transfer function of this circuit is T (S), the transfer function of the acoustic system including the speaker 42 and the microphone 5 is A (constant), the adder / subtracter 7
When the amplification degree of the subtracter 2 is 1, the input voltage is V _in , and the output voltage of the power amplifier 3 is V _out , V _out / V _in = A / (2 + A · T (S)) Similarly, the transfer function of the block diagram of the sound reproducing apparatus described with reference to FIG. 87 in the conventional example is as follows: V _out / V _in = A / (1 + A · T (S))

That is, since the frequency characteristic of the microphone 5 is almost flat, T (S) is equal to the speaker 42, the passive radiator 43, and the front and rear closed spaces 41A, 41A.
B becomes a transfer function of an acoustic system composed of B, and a phase difference between a signal output from the power amplifier 3 and an output signal of the microphone 5 due to resonance (low-band resonance) including the speaker 42, the passive radiator 43, and the closed spaces 41A and 41B. When the phase changes by plus or minus 180 degrees (the phase is inverted), T (S) becomes minus one, and the power amplifier 3
Assuming that the amplification factor A is 1, the denominator becomes 0 and oscillates in the circuit of the conventional configuration, but the transfer function of the circuit according to the present embodiment is 1, and the stability of feedback under the same conditions can be secured. It can be seen that it is.

Further, since the position of the microphone 5 has a very large sound pressure and external noise is greatly attenuated by the passive radiator 43, a high S / N ratio can be obtained.

FIGS. 33, 34 and 35 show the frequency characteristics of the input signal of the sound reproducing apparatus of the present embodiment, the frequency characteristics when the acoustic output of the passive radiator 43 is controlled by the feedback circuit, and the frequency characteristics when the control is not performed. , Respectively, and it can be seen that the characteristics subjected to feedback are closer to the input original signal.

FIG. 36 shows an acoustic signal waveform radiated from the passive radiator 43 when a 60 Hz tone burst wave (10 waves on, 1 wave off) is input in the case of control, and FIG. 37 shows an acoustic signal waveform in the case of no control. It is an acoustic signal waveform. When these are compared, it can be understood that the level is reduced by controlling the portion where one wave is off, and the rise and fall characteristics of the passive radiator 43 are improved as compared with the uncontrolled signal waveform.

Embodiment 32 Hereinafter, a thirty-second embodiment of the present invention will be described with reference to the drawings.

FIG. 38 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment, in which a filter 44 is inserted between the microphone amplifier 6 and the adder / subtractor 7, and the other configuration is the same as that of the above embodiment. Same as Example 31.

With this configuration, it is possible to control the sound quality and frequency characteristics of the system in the same manner as in the thirty-first embodiment.

Embodiment 33 Hereinafter, a thirty-third embodiment of the present invention will be described with reference to the drawings.

FIG. 39 is a block diagram showing the configuration of the sound reproducing apparatus according to the present embodiment, in which a phase shift circuit 45 is inserted between the microphone amplifier 6 and the adder / subtractor 7, and other configurations are the same. This is the same as Example 31 above.

With this configuration, it is possible to control the sound quality and frequency characteristics of the system in the same manner as in the thirty-first embodiment.

Embodiment 34 Hereinafter, a thirty-fourth embodiment of the present invention will be described with reference to the drawings.

FIG. 40 is a block diagram showing a configuration of the sound reproducing apparatus according to the embodiment, in which a filter 44 and a phase shift circuit 45 are inserted between the microphone amplifier 6 and the adder / subtractor 7, and Is the same as that of the third embodiment.
Same as 1.

With this configuration, it is possible to control the feedback band and phase in the same manner as in the thirty-first embodiment.

(Embodiment 35) Hereinafter, a thirty-fifth embodiment of the present invention will be described with reference to the drawings.

FIG. 41 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment. The output of the microphone amplifier 6 is branched into two, and the branched outputs are divided into a first filter 46A and a first filter 46A having different characteristics. Filter 46B of 2
And the output of the first filter 46A and the output of the second filter 46B passed through an inverting circuit 47 are connected to an adder 48. The output of the adder 48 is
The other configuration is the same as that of the above-described embodiment 31.

With this configuration, it is possible to expand the degree of freedom in controlling the sound quality and frequency characteristics of the system as in the case of the thirty-first embodiment.

(Embodiment 36) A thirty-sixth embodiment of the present invention will be described below with reference to the drawings.

FIG. 42 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment. In this embodiment, a phase shift circuit 45 is used instead of the inverting circuit 47 of the embodiment 35 described with reference to FIG. Except for this configuration, the configuration is the same as that of the embodiment 35.

With this configuration, it is possible to expand the degree of freedom in controlling the sound quality and frequency characteristics of the system as in the case of the thirty-fifth embodiment.

(Embodiment 37) A thirty-seventh embodiment of the present invention will be described below with reference to the drawings.

FIG. 43 is a block diagram showing the structure of the sound reproducing apparatus according to this embodiment. In this embodiment, the microphone 5 shown in FIG. Is arranged in the closed space portion 41A of the third embodiment.
Same as 1.

In the sound reproducing apparatus of the present embodiment thus configured, the output signal of the power amplifier 3 is connected to the speaker 42, and the speaker 42 is driven to drive the closed space 41 in the front.
B causes a pressure change. At this time, the rear sealed space 41A generates a pressure change having a phase different from that of the front sealed space 41B, and the pressure change in the rear sealed space 41A is detected by the microphone 5, and the rear sealed space 41A is configured. The pressure change at
When the speaker 42 and the passive radiator 43 resonate in opposite phases, they become maximum at the frequency at which the passive radiator 43 resonates in phase.

Therefore, it is possible to improve the transient characteristics when the speaker 42 and the passive radiator 43 resonate in phase.

Embodiment 38 Hereinafter, a thirty-eighth embodiment of the present invention will be described with reference to the drawings.

FIG. 44 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment. In this embodiment, the microphone amplifier 6 and the adder / subtractor 7 of the 37th embodiment described with reference to FIG. The configuration is such that a filter 44 is inserted between them, and the other configuration is the same as that of the 37th embodiment.

With this configuration, the sound quality and frequency characteristics of the system can be controlled in the same manner as in the thirty-seventh embodiment.

(Embodiment 39) Hereinafter, a thirty-ninth embodiment of the present invention will be described with reference to the drawings.

FIG. 45 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment. In this embodiment, the microphone amplifier 6 and the adder / subtractor 7 of the 37th embodiment described with reference to FIG. The configuration is such that a phase shift circuit 45 is inserted between them, and the other configuration is the same as that of the 37th embodiment.

With this configuration, the sound quality and frequency characteristics of the system can be controlled in the same manner as in the thirty-seventh embodiment.

(Embodiment 40) Hereinafter, a fortieth embodiment of the present invention will be described with reference to the drawings.

FIG. 46 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment. In this embodiment, the microphone amplifier 6 and the adder / subtractor 7 of the 37th embodiment described with reference to FIG. Filter 44 and phase shift circuit 45 between
Are inserted, and the other configuration is the same as that of the 37th embodiment.

With this configuration, the sound quality and frequency characteristics of the system can be controlled in the same manner as in the thirty-seventh embodiment.

(Embodiment 41) A forty-first embodiment of the present invention will be described below with reference to the drawings.

FIG. 47 is a block diagram showing the structure of the sound reproducing apparatus according to this embodiment. In this embodiment, two outputs of the microphone amplifier 6 having the structure of the 37th embodiment described with reference to FIG. Are connected to a first filter 46A and a second filter 46B having different characteristics, and an inverting circuit 47 is connected to the output of the first filter 46A and the output of the second filter 46B. The passed output is connected to an adder 48, and the output of the adder 48 is connected to the adder / subtractor 7. The other configuration is the same as that of the embodiment 37.

With this configuration, the degree of freedom in controlling the sound quality and frequency characteristics of the system can be increased, as in the thirty-seventh embodiment.

(Embodiment 42) Hereinafter, a forty-second embodiment of the present invention will be described with reference to the drawings.

FIG. 48 is a block diagram showing the configuration of the sound reproducing apparatus according to the present embodiment. In this embodiment, a phase shift circuit 45 is used instead of the inverting circuit 47 of the embodiment 41 described with reference to FIG. The other configuration is the same as that of the forty-first embodiment.

With this configuration, it is possible to expand the degree of freedom in controlling the sound quality and frequency characteristics of the system, as in the forty-first embodiment.

(Embodiment 43) A forty-third embodiment of the present invention will be described below with reference to the drawings.

FIG. 49 is a block diagram showing the structure of the sound reproducing apparatus according to this embodiment. In this embodiment, the location of the microphone 5 shown in FIG. The configuration is arranged inside the closed space portion 41B on the side, and the other configuration is the same as that of the embodiment 31.

In the sound reproducing apparatus of this embodiment thus configured, the signal input from the input terminal 1 is connected to the subtractor 2, the output signal of the subtracter 2 is connected to the power amplifier 3, 3 is connected to the speaker 42, and the speaker 42 is driven by the output signal of the power amplifier 3. The pressure change by the speaker 42 is transmitted to the air in the front sealed space 41B, the pressure change in the sealed space 41B is transmitted to the passive radiator 43, and the sound of the passive radiator 43 is radiated to the outside by the vibration.

The microphone 5 detects a pressure change in the front closed space 41B that vibrates the passive radiator 43. The detected signal is supplied to the microphone amplifier 6
The output signal of the microphone amplifier 6 and the output signal of the subtractor 2 are connected to the adder / subtractor 7, and the adder / subtractor 7 performs subtraction or addition processing. The output signal of the adder / subtractor 7 is connected to the subtractor 2 to form a feedback circuit.

The adder / subtractor 7 is used as an adder when the output signal of the microphone 5 is in phase with the signal at the input terminal 1, and is used as a subtractor when the output signal is out of phase. The transfer function of the entire system in this case can be expressed as follows.

V _out / V _in = G / (2 + GH) where G: amplification degree of power amplifier, H: transfer function of speaker / microphone, V _in : input voltage, V _out : output voltage of power amplifier It is.

In the above transfer function, G: the amplification degree of the power amplifier is set to 1, and H: the transfer function of the speaker / microphone is also set to 1. Considering a case where a steady positive-phase signal is fed back, V _out / V _in = 1/3 and made whereas, the transfer function V _out / V _in = 1/2 next to when the feedback signal before the loudspeaker 42 rises becomes 0 until the speaker 42 begins to operate, the power amplifier 3 , About 3.6 dB higher power is supplied to the speaker 42.

Further, the transfer function in the case where the negative-phase signal is fed back is V _out / V _in = 1, which indicates that no oscillation (howling) occurs.

[0173] Comparing this transmission of a general single feedback loop function V _out / V _in = G / a (1 + G · H), the output power difference of the power amplifier 3 of the operation before and after the start of the speaker 42 is a 6dB However, when the negative-phase signal is fed back, V _out / V _in = ∞, which indicates that oscillation (howling) occurs.

FIG. 50 shows the output characteristic of the microphone 5 in the closed space 41B in front of the sound reproducing apparatus according to the present embodiment. The microphone 5 has two resonance peaks _f01 and _f02, and has a phase between them. Turns one rotation. Further, it is understood that the sound pressure at the portion where the phase is inverted between the f ₀₁ and f ₀₂ is reduced.

[0175] By applying a positive phase consisting feedback at f ₀₁ and f ₀₂ Therefore, the improvement of the transient characteristics at the resonant frequency, the sound pressure increases in a portion where the sound pressure between f ₀₁ and f ₀₂ is reduced It can be seen that it can be realized.

The tone burst output waveforms (10 waves on, 1 wave off) with and without feedback control in the sound reproducing apparatus of this embodiment are the same as the characteristics shown in FIGS. 36 and 37. It can be seen that the output is clearly stopped when the control is applied.

(Embodiment 44) A forty-fourth embodiment of the present invention will be described below with reference to the drawings.

FIG. 51 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment. In this embodiment, the microphone amplifier 6 and the adder / subtractor 7 of the forty-third embodiment described with reference to FIG. The configuration is such that a filter 44 is inserted between them, and the other configuration is the same as that of the forty-third embodiment.

With this configuration, the sound quality and frequency characteristics of the system can be controlled in the same manner as in the forty-third embodiment.

(Embodiment 45) A forty-fifth embodiment of the present invention will be described below with reference to the drawings.

FIG. 52 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment. In this embodiment, the microphone amplifier 6 and the adder / subtractor 7 of the 43rd embodiment described with reference to FIG. The configuration is such that a phase shift circuit 45 is inserted between them, and the other configuration is the same as that of the forty-third embodiment.

With this configuration, the frequency characteristics of the negative feedback and the positive feedback can be controlled by controlling the phase of the output signal of the microphone amplifier 6, and the sound quality of the system can be controlled in the same manner as in the forty-third embodiment. And frequency characteristics can be controlled.

(Embodiment 46) A forty-sixth embodiment of the present invention will be described below with reference to the drawings.

FIG. 53 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment. In this embodiment, the microphone amplifier 6 and the adder / subtractor 7 of the forty-third embodiment described with reference to FIG. Filter 44 and phase shift circuit 45 between
Are inserted, and other configurations are the same as those of the forty-third embodiment.

With such a configuration, the microphone
The output signal of the lophone amplifier 6 is
Range control and the phase shift circuit 45
Can be controlled. For example, as shown in FIG.
Roller f₀₁Pass higher frequencies and start with positive feedback
And f₀₂Using a phase shift circuit that provides negative feedback at
₀₁In the following band, high output sound pressure without feedback is realized, and f
₀₁In the above band, negative feedback is applied to the entire reproduction band.
It can achieve excellent sound quality with excellent transient characteristics.

(Embodiment 47) A forty-seventh embodiment of the present invention will be described below with reference to the drawings.

FIG. 54 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment. In this embodiment, two outputs of the microphone amplifier 6 having the configuration of the forty-third embodiment described with reference to FIG. 49 are used. Are connected to a first filter 46A and a second filter 46B having different characteristics, and an inverting circuit 47 is connected to the output of the first filter 46A and the output of the second filter 46B. The passed output is connected to an adder 48, and the output of the adder 48 is connected to the adder / subtractor 7. The other configuration is the same as that of the forty-third embodiment.

With such a configuration, the output signal of the microphone amplifier 6 is divided into signals of two bands, each of which is divided into a positive feedback and a negative feedback, and is subjected to feedback. The degree of freedom to control the characteristics increases.

[0189] For example a bandwidth of less than f ₀₁ where shown in FIG. 50, divided into f ₀₁ or more bands, positive feedback bandwidth of less than f _01, by a negative feedback to f ₀₁ or more bands, the The characteristic that the band of _f01 or less is increased in the sound quality shown in the embodiment 31 is obtained.

Embodiment 48 Hereinafter, a forty-eighth embodiment of the present invention will be described with reference to the drawings.

FIG. 55 is a block diagram showing the configuration of the sound reproducing apparatus according to this embodiment. In this embodiment, a phase shift circuit 45 is used in place of the inverting circuit 47 of the embodiment 47 described with reference to FIG. The configuration is the same as that of the forty-seventh embodiment except for this configuration.

With such a configuration, the output signal of the microphone amplifier 6 is divided into signals of two different bands, and feedback is performed separately in positive feedback and negative feedback. Connected second filter 46B
, The polarity of the feedback can be changed in the band, and the degree of freedom for controlling the sound quality and frequency characteristics of the system increases.

[0193] divided for example into f ₀₁ below the band and a high frequency band higher than f ₀₁ where shown in FIG. 50 begins with the positive feedback of the frequency band higher than f _01, using a phase shift circuit as a negative feedback in f ₀₂ If so, negative feedback can be applied in the entire reproduction band of the speaker system.

(Embodiment 49) A forty-ninth embodiment of the present invention will be described below with reference to the drawings.

FIG. 56 is a block diagram showing the configuration of the sound reproducing apparatus according to the present embodiment. Two microphones for detecting the sound output signal radiated from the speaker 42 are arranged in the speaker box 41, and one microphone is provided. Is on the upper surface of the magnetic circuit of the speaker 42, and the other is the rear closed space 4
First and second microphones 5A and 5B are provided in 1A, respectively.

The output signals of the two microphones 5A and 5B are connected to first and second microphone amplifiers 6A and 6B, respectively. The output signals of the first and second microphone amplifiers 6A and 6B are , A second adder / subtractor 7B, and an output signal of the second adder / subtractor 7B and an output signal of the subtractor 2 are connected to a first adder / subtractor 7A. The output signal is connected to the subtractor 2 to form a feedback circuit.

With this configuration, for example, when the second adder / subtractor 7B is a subtractor, the low frequency (f
₀₁ or less) and the feedback signal of 500 Hz or more, in which the phase is completely inverted, can be reduced.
It can be seen that the reproduction band of f ₀₁ or more, which is indicated by 0, is stable even if the feedback amount is increased.

Further, the second adder / subtractor 7B is used as an adder, and a signal in which the output signals of the first and second microphone amplifiers 6A and 6B have opposite phases is added to the input signal.
Further, by adding the output signal of the second adder / subtractor 7B by the first adder / subtractor 7A, it is possible to control the sound quality and frequency characteristics of the loudspeaker system, such as producing a signal for low-frequency reproduction in which high-frequency components are cut. It is possible to provide a system having a greater degree of freedom than the above embodiments.

(Embodiment 50) Hereinafter, a fiftieth embodiment of the present invention will be described with reference to the drawings.

FIGS. 57 and 58 are block diagrams showing the structure of the sound reproducing apparatus according to this embodiment. In the embodiment shown in FIG. 57, a filter 44 is connected to the output signal of the second microphone amplifier 6B, 44 output signal and the first
And the output signal of the microphone amplifier 6A is connected to a second adder / subtractor 7B.

In the embodiment shown in FIG. 58, the filter 44 is connected to the output signal of the first microphone amplifier 6A, and the output signal of the filter 44 and the output signal of the second microphone amplifier 6B are subjected to the second addition and subtraction. 57 and FIG. 58, and the other configuration is the same as that of the forty-ninth embodiment.

With this configuration, it is possible to reduce the amount of positive feedback by adding another microphone signal to the frequency at which one microphone becomes positive feedback. Also, with one microphone, it is possible to apply an output signal from another microphone and apply feedback to a band where the phase shift becomes 90 ° with respect to the input signal and no feedback is applied.
Further increase the degree of freedom of control, sound quality of the speaker system,
The frequency characteristics can be created more precisely.

(Embodiment 51) A 51st embodiment of the present invention will be described below with reference to the drawings.

FIGS. 59 and 60 are block diagrams showing the structure of the sound reproducing apparatus according to this embodiment. The phase shift circuit 45 is used in place of the filter 44 of the embodiment 50 described with reference to FIGS. 57 and 58. In the embodiment shown in FIG. 59, a phase shift circuit 45 is connected to the output signal of the second microphone amplifier 6B, and the output signal of the phase shift circuit 45 is connected to the output signal of the first microphone amplifier 6A. The output signal is connected to a second adder / subtractor 7B.

In the embodiment shown in FIG. 60, a phase shift circuit 45 is connected to the output signal of the first microphone amplifier 6A, and the output signal of this phase shift circuit 45 and the output signal of the second microphone amplifier 6B are connected. It is configured to be connected to the second adder / subtractor 7B.
Other configurations are the same as those of the above-described embodiment 50.

With this configuration, the phase shift
By the path 45, f shown in FIG. ₀₁Invert the above band
When the second adder / subtractor 7B is operated as a subtractor.
In this case, the first microphone amplifier 6A and the second microphone
The output signal of the phone amplifier 6B has the same phase as the input signal.
Some f₀₁The following signal and both output signals are inverse to the input signal
It is possible to reduce the phase of the mid-high range signal,
A feedback signal limited to the reproduction band of the speaker system
It can be created.

When the output signals of the first and second microphone amplifiers 6A and 6B have opposite phases in the band where feedback control is desired and the feedback signal decreases, the phase shift where the phase is inverted at the opposite frequency point. Circuit 4
By using 5, it becomes possible to match the phase of the feedback signal, and it is possible to prevent the feedback signal from decreasing.

With the above configuration, the feedback band can be limited and the amount of feedback can be increased, and the stability of the system can be improved.

(Embodiment 52) Hereinafter, a 52nd embodiment of the present invention will be described with reference to the drawings.

FIG. 61 is a block diagram showing the configuration of the sound reproducing apparatus according to the embodiment. In this embodiment, in addition to the configuration of the embodiment 49 described with reference to FIG. 56, the output of the first microphone amplifier 6A is shown. The signal is connected to the first filter 44A, the output signal of the second microphone amplifier 6B is connected to the second filter 44B, and the output signal of the first filter 44A and the output signal of the second filter 44B are further connected. The configuration is connected to the second adder / subtractor 7B, and the other configuration is the same as that of the forty-ninth embodiment.

With such a configuration, the signals of the microphones 5A and 5B can be band-limited, and only the band in which the signals of the microphones 5A and 5B are in phase with the input signal is extracted. Second
Or the adder / subtractor 7B of the other microphone works as an adder, or a band in which the signal of one microphone is in phase with the input signal, and a band in which the signal of the other microphone is in phase with the input signal is extracted. By extracting a band in which the signal has a phase opposite to that of the input signal and causing the second adder / subtractor 7B to function as a subtractor,
Compared to a single microphone, it is possible to apply deeper feedback or to apply negative feedback over a wider band.

(Embodiment 53) Hereinafter, a fifty-third embodiment of the present invention will be described with reference to the drawings.

FIGS. 62 and 63 are block diagrams showing the structure of the sound reproducing apparatus according to this embodiment. The embodiment shown in FIG. 62 has the structure of the embodiment 49 described with reference to FIG.
The output signal of the first microphone amplifier 6A is connected to the filter 44, and the second microphone amplifier 6A is connected to the filter 44.
The output signal of B is connected to the phase shift circuit 45, and the output signal of the filter 44 and the output signal of the phase shift circuit 45 are connected to the second adder / subtractor 7B. Is the same as

In the embodiment shown in FIG. 63, the phase shift circuit 45 is connected to the first microphone amplifier 6A, and the filter 44 is connected to the second microphone amplifier 6B. Is the same.

With such a configuration, the output signal of the microphone connected to the phase shift circuit 45 is feedback-controlled as the main signal, and the frequency at which the feedback amount is to be increased or the feedback amount is to be reduced is determined. The other microphone signal is filtered and added or subtracted by the second adder / subtractor 7B, whereby the frequency and amount of feedback can be controlled, and the sound quality and frequency characteristics of the system can be controlled. It can expand the range that can be done.

(Embodiment 54) A 54th embodiment of the present invention will be described below with reference to the drawings.

FIGS. 64 and 65 are block diagrams showing the structure of the sound reproducing apparatus according to this embodiment. The embodiment shown in FIG. 64 is the same as the embodiment 49 described with reference to FIG.
The output signal of the first microphone amplifier 6A is connected to a first filter 44A and the first filter 4A is connected to the first filter 44A.
The output signal of 4A was connected to a phase shift circuit 45, and the output signal of the phase shift circuit 45 and the output signal from the second microphone amplifier 6B passed through the second filter 44B were connected to a second adder / subtractor 7B. It has a configuration.

In the embodiment shown in FIG. 65, the output signal from the second microphone amplifier 6B passed through the second filter 44B is connected to the phase shift circuit 45, and the output signal of the phase shift circuit 45 and the first The output signal from the microphone amplifier 6A through the first filter 44A and the second adder / subtracter 7
The configuration is connected to B, and the other configuration is the same as that of the forty-ninth embodiment.

With such a configuration, the microphone signal on the side to which the phase shift circuit 45 is connected
The passband is expanded beyond the band shown in Embodiment 52,
By using a phase shift circuit in which the phase is inverted in the band where positive feedback is provided, stable feedback can be realized in a wider band, and the degree of freedom in controlling the sound quality and frequency characteristics of the speaker system can be increased.

(Embodiment 55) Hereinafter, a fifty-fifth embodiment of the present invention will be described with reference to the drawings.

FIG. 66 is a block diagram showing the structure of the sound reproducing apparatus according to this embodiment. The second microphone 5 for detecting pressure is provided in the closed space 41B in front of the speaker 42.
B, the first microphone 5A is installed in the space (the upper surface of the magnetic circuit) defined by the pole piece center of the speaker 42 and the dust cap, and the other configuration is described with reference to FIG. This is the same as Embodiment 49.

With this configuration, it is possible to detect the operating state of the diaphragm of the speaker 42 and the pressure in the closed space 41B that drives the passive radiator 43. In this case, the transient characteristics are improved by applying a negative feedback by the first microphone 5A when the operation of the speaker 42 is started. When the passive radiator 43 does not operate even if the speaker 42 operates for the first time, the front closed space is Part 41B
Is increased, and the information is detected by the second microphone 5B.

By using the information of the second microphone 5B as positive feedback, the front closed space 41B
It works in a direction to further increase the internal pressure, so that the rise time of the passive radiator 43 can be further shortened, and thus the transient characteristics can be greatly improved.

(Embodiment 56) A 56th embodiment of the present invention will be described below with reference to the drawings.

FIGS. 67 and 68 are block diagrams showing the structure of the sound reproducing apparatus according to this embodiment. In the embodiment shown in FIG. 67, in addition to the structure of the embodiment 55 described with reference to FIG. The output signal of the microphone amplifier 6B is connected to the filter 44, and the output signal of the filter 44 is
Connected to the adder / subtractor 7B.

In the embodiment shown in FIG. 68, the output signal of the first microphone amplifier 6A is connected to the filter 44, and the output signal of the filter 44 is connected to the second adder / subtracter 7B.
The other configuration is the same as that of Embodiment 55 described above.
Is the same as

With this configuration, as in the case of the fifty-fifth embodiment, the control range of the sound quality and frequency characteristics of the system can be expanded.

(Embodiment 57) Hereinafter, a fifty-seventh embodiment of the present invention will be described with reference to the drawings.

FIGS. 69 and 70 are block diagrams showing the structure of the sound reproducing apparatus according to this embodiment. The embodiment shown in FIG. 69 is similar to the embodiment 55 shown in FIG. The output signal of the microphone amplifier 6B is connected to the phase shift circuit 45, and the output signal of the phase shift circuit 45 is connected to the second
Connected to the adder / subtractor 7B.

In the embodiment shown in FIG. 70, the output signal of the first microphone amplifier 6A is connected to the phase shift circuit 45, and the output signal of the phase shift circuit 45 is connected to the second adder / subtracter 7B.
The other configuration is the same as that of the above-described embodiment 55.

By adopting such a configuration, the feedback band can be limited and the amount of feedback can be increased, as in the fifty-fifth embodiment, and the stability of the system can be improved.

(Embodiment 58) Hereinafter, a fifty-eighth embodiment of the present invention will be described with reference to the drawings.

FIG. 71 shows the structure of the sound reproducing apparatus according to this embodiment. In this embodiment, in addition to the structure of the embodiment 55 shown in FIG. 66, a first microphone amplifier 6A and a second microphone amplifier 6A are provided. The first filter 44A is inserted between the adder / subtractor 7B of the second microphone amplifier 6B and the second microphone amplifier 6A.
B and a second filter 44B between the second adder / subtractor 7B.
Are inserted, and the other configuration is the same as that of the above-described embodiment 55.

By adopting such a configuration, it is possible to apply deep feedback as in Embodiment 52 or to apply negative feedback over a wider band.

(Embodiment 59) Hereinafter, a fifty-ninth embodiment of the present invention will be described with reference to the drawings.

FIGS. 72 and 73 are block diagrams showing the structure of the sound reproducing apparatus according to this embodiment. The embodiment shown in FIG. 72 is similar to the embodiment 55 shown in FIG. The filter 44 is inserted between the microphone amplifier 6A and the second adder / subtractor 7B, and the phase shift circuit 45 is inserted between the second microphone amplifier 6B and the second adder / subtractor 7B.

In the embodiment shown in FIG. 73, the phase shift circuit 45 is provided between the first microphone amplifier 6A and the second adder / subtractor 7B, and the phase shift circuit 45 is provided between the second microphone amplifier 6B and the second adder / subtractor 7B. The configuration is such that a filter 44 is inserted between them, and the other configuration is the same as that of the above-described embodiment 55.

With such a configuration, the frequency characteristics of the feedback signal can be controlled in the same manner as in the fifty-third embodiment, and the range in which the sound quality frequency characteristics of the system can be controlled can be expanded.

(Embodiment 60) A 60th embodiment of the present invention will be described below with reference to the drawings.

FIGS. 74 and 75 are block diagrams showing the structure of the sound reproducing apparatus according to this embodiment. In the embodiment shown in FIG. 74, in addition to the structure of the embodiment 58 described with reference to FIG. 7 has a configuration in which a phase shift circuit 45 is inserted between the filter 44A and the second adder / subtractor 7B.
In the embodiment shown in FIG. 5, a phase shift circuit 45 is inserted between the second filter 44B and the second adder / subtractor 7B, and the other structure is the same as that of the embodiment 58. .

By adopting such a configuration, stable feedback can be realized in a wide band, and the degree of freedom in controlling the sound quality and frequency characteristics of the loudspeaker system can be increased, as in the fifty-fourth embodiment.

(Embodiment 61) Hereinafter, a 61st embodiment of the present invention will be described with reference to the drawings.

FIG. 76 is a block diagram showing the structure of the sound reproducing apparatus according to this embodiment. The first microphone 5 for pressure detection is provided in the closed space 41A behind the speaker 42.
A has a second microphone 5B installed in the front closed space portion 41B.

In addition, the first and second microphones 5
A and 5B are connected to first and second microphone amplifiers 6A and 6B, respectively, and the output signals of the first and second microphone amplifiers 6A and 6B are connected to a second adder / subtractor 7B.
And the output signal of the second adder / subtractor 7B and the output signal of the subtractor 2 are connected to the first adder / subtractor 7A. The other configuration is the same as that of the above-described embodiment 55. is there.

With such a configuration, the first microphone 5A detects a pressure change in which the speaker 42 and the passive radiator 43 vibrate in phase, and detects a pressure change in which the speaker 42 and the passive radiator 43 vibrate in opposite phase. 5B, and pressure changes at all resonances can be detected.

Further, by using the second adder / subtractor 7B as an adder, feedback can be canceled in a band in which the rear enclosed space 41A and the front enclosed space 41B have opposite phases, and the lowest resonance can be achieved. It is possible to increase the output sound pressure below the frequency.

Alternatively, by using the second adder / subtractor 7B as a subtractor, it is possible to deeply apply feedback when the speaker 42 and the passive radiator 43 resonate in opposite phases. The feedback to the resonance of the system can be more accurately applied.

(Embodiment 62) A 62nd embodiment of the present invention will be described below with reference to the drawings.

FIGS. 77 and 78 are block diagrams showing the structure of the sound reproducing apparatus according to this embodiment. In the embodiment shown in FIG. 77, the output signal of the first microphone amplifier 6A is connected to the filter 44, 44 output signal and the second
The output signal of the microphone amplifier 6B is connected to a second adder / subtractor 7B.

In the embodiment shown in FIG. 78, the output signal of the second microphone amplifier 6B is connected to a filter 44, and the output signal of the filter 44 and the output signal of the first microphone amplifier 6A are connected to a second adder / subtracter. 7B, and the other configuration is the same as that of the embodiment 61.

With this configuration, it is possible to reduce the amount of positive feedback by adding a signal from another microphone to a frequency point at which one microphone becomes positive feedback.

Only the frequency for which the feedback amount is to be increased is 2
It can expand the way of control, such as adding a microphone signal from a book.

Embodiment 63 Hereinafter, a 63rd embodiment of the present invention will be described with reference to the drawings.

FIGS. 79 and 80 are block diagrams showing the configuration of the sound reproducing apparatus according to the embodiment. In the embodiment shown in FIG. 79, the output signal of the first microphone amplifier 6A is connected to the phase shift circuit 45, The output signal of the phase shift circuit 45 and the second
The output signal of the microphone amplifier 6B is connected to the second adder / subtractor 7B.

In the embodiment shown in FIG. 80, the output signal of the second microphone amplifier 6B is connected to the phase shift circuit 45, and the output signal of the phase shift circuit 45 and the output signal of the first microphone amplifier 6A are connected to the first microphone amplifier 6A. The configuration is connected to the second adder / subtractor 7B, and the other configuration is the same as that of the embodiment 61.

By adopting such a configuration, even when two microphones have frequencies opposite to each other and are not feedbackable, the feedback frequency can be increased by using a phase shift circuit having the same phase. .

Further, by using a phase shift circuit having an opposite phase at a frequency at which both microphones have positive feedback, the amount of positive feedback can be reduced by reducing a feedback signal.

With the above configuration, the feedback amount and the stability can be increased, and the control range of the sound quality and frequency characteristics of the system can be expanded.

(Embodiment 64) A sixty-fourth embodiment of the present invention will be described below with reference to the drawings.

FIG. 81 is a block diagram showing the structure of the sound reproducing apparatus according to the embodiment.
In addition, the output signal of the first microphone amplifier 6A is connected to the first filter 44A, and the output signal of the second microphone amplifier 6B is connected to the second filter 44A.
B, and the output signal of the first filter 44A and the output signal of the second filter 44B are connected to the second adder / subtractor 7B. Other configurations are the same as those of the embodiment 61. It is.

With such a configuration, both microphone signals can be band-limited. For example, when only negative feedback is desired to be realized, each microphone output passes only the band where negative feedback is provided.
By adding and combining the feedback signals, it is possible to realize stable feedback over a wide frequency range as compared with a single microphone.

Embodiment 65 Hereinafter, a 65th embodiment of the present invention will be described with reference to the drawings.

FIGS. 82 and 83 are block diagrams showing the structure of the sound reproducing apparatus according to this embodiment. The embodiment shown in FIG. 82 is similar to the embodiment 61 shown in FIG. The output signal of the first microphone amplifier 6A is connected to a phase shift circuit 45, the output signal of the second microphone amplifier 6B is connected to a filter 44, and the output signal of the phase shift circuit 45 and the output signal of the filter 44 are 2 is connected to the adder / subtractor 7B.

In the embodiment shown in FIG. 83, the output signal of the first microphone amplifier 6A is connected to the filter 44, and the output signal of the second microphone amplifier 6B is connected to the phase shift circuit 45. And the output signal of the phase shift circuit 45 are connected to the second adder / subtractor 7B.
Same as 1.

With such a configuration, feedback is controlled in the same manner as in the above-described embodiment 64, mainly using a microphone connected to the phase shift circuit 45, and further increasing the amount of feedback or reducing the amount of feedback. A desired frequency can be obtained by filtering another microphone signal, and by adding or subtracting it, more stable feedback can be realized in a wide frequency range.

(Embodiment 66) A 66th embodiment of the present invention will be described below with reference to the drawings.

FIGS. 84 and 85 are block diagrams showing the configuration of the sound reproducing apparatus according to this embodiment. The embodiment shown in FIG. 84 has the same structure as the embodiment 61 described with reference to FIG. The output signal from the microphone amplifier 6A through the first filter 44A is connected to the phase shift circuit 45, and the output signal from the phase shift circuit 45 and the output from the second microphone amplifier 6B through the second filter 44B. The signal is connected to the second adder / subtractor 7B.

In the embodiment shown in FIG. 85, the output signal passed from the second microphone amplifier 6B through the second filter 44B is connected to the phase shift circuit 45, and the output signal of the phase shift circuit 45 and the first The output signal from the microphone amplifier 6A passing through the first filter 44A is converted into a second adder / subtractor 7B.
The other configuration is the same as that of the above-described embodiment 61.

By adopting such a configuration, for example, when it is desired to realize only negative feedback, in addition to extracting the frequency band to be negative feedback by the filter 44A or 44B, the microphone signal connected to the phase shift circuit 45 is positive feedback. In this case, stable feedback can be realized in a wide band by passing the signal through the band up to the band and making the band that becomes the positive feedback the opposite phase by the phase shift circuit 45.

[0270]

As described above, the use of the sound reproducing apparatus according to the present invention makes it possible to apply feedback stably, fully exploit the advantage of negative feedback, and improve the acoustic characteristics of the speaker and its surroundings. It is possible to obtain excellent characteristics.

Also, in the sound reproducing apparatus using the speaker box incorporating the passive radiator, the acoustic characteristics of the speaker in which the passive radiator is connected to the closed space connected before and after the speaker and the closed space in front of the speaker are greatly improved. It is possible to automatically correct the acoustic characteristics even if the characteristics of the speaker or the passive radiator change because the detection signal of the microphone is used as a reference. The degree of contribution is great.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a sound reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a sound reproducing apparatus according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a sound reproducing apparatus according to Embodiment 3 of the present invention.

FIG. 4 is a block diagram illustrating a sound reproducing apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a sound reproducing apparatus according to Embodiment 5 of the present invention.

FIG. 6 is a block diagram showing a sound reproducing apparatus according to a sixth embodiment of the present invention.

FIG. 7 is a block diagram showing a sound reproducing apparatus according to a seventh embodiment of the present invention.

FIG. 8 is a block diagram showing an audio reproducing apparatus according to an eighth embodiment of the present invention.

FIG. 9 is a block diagram showing a sound reproducing apparatus according to Embodiment 9 of the present invention.

FIG. 10 is a block diagram showing a sound reproducing apparatus according to Embodiment 10 of the present invention.

FIG. 11 is a block diagram showing a sound reproducing apparatus according to Embodiment 11 of the present invention.

FIG. 12 is a block diagram showing a sound reproducing apparatus according to Embodiment 12 of the present invention.

FIG. 13 is a block diagram showing a sound reproducing apparatus according to Embodiment 13 of the present invention.

FIG. 14 is a block diagram showing a sound reproducing apparatus according to Embodiment 14 of the present invention.

FIG. 15 is a block diagram showing a sound reproducing apparatus according to Embodiment 15 of the present invention.

FIG. 16 is a block diagram showing a sound reproducing apparatus according to Embodiment 16 of the present invention.

FIG. 17 is a block diagram showing a sound reproducing apparatus according to Embodiment 17 of the present invention;

FIG. 18 is a block diagram showing a sound reproducing apparatus according to Embodiment 18 of the present invention.

FIG. 19 is a block diagram showing a sound reproducing apparatus according to Embodiment 19 of the present invention.

FIG. 20 is a block diagram showing a sound reproducing apparatus according to Embodiment 20 of the present invention.

FIG. 21 is a block diagram showing a basic configuration of a sound reproducing device according to Embodiment 21 of the present invention.

FIG. 22 is a block diagram showing a sound reproducing apparatus according to Embodiment 21 of the present invention.

FIG. 23 is a block diagram showing a basic configuration of a sound reproducing device according to Embodiment 22 of the present invention.

FIG. 24 is a block diagram showing a sound reproducing apparatus according to Embodiment 22 of the present invention.

FIG. 25 is a block diagram showing a sound reproducing apparatus according to Embodiment 23 of the present invention.

FIG. 26 is a block diagram showing a sound reproducing apparatus according to Embodiment 24 of the present invention.

FIG. 27 is a half sectional view showing an arrangement of speakers and microphones of the sound reproducing apparatus according to Embodiments 25 to 30 of the present invention.

FIG. 28 is a characteristic diagram showing frequency characteristics according to the first embodiment.

FIG. 29 is a characteristic diagram illustrating frequency characteristics according to the first embodiment.

FIG. 30 is a characteristic diagram illustrating frequency characteristics according to the third embodiment.

FIG. 31 is a block diagram showing a sound reproducing apparatus according to Embodiment 31 of the present invention.

FIG. 32 is a half sectional view showing the speaker according to the embodiment.

FIG. 33 is a frequency characteristic diagram of an input signal of the sound reproducing apparatus according to the embodiment.

FIG. 34 is a frequency characteristic diagram when the passive radiator of the sound reproducing device according to the embodiment is controlled.

FIG. 35 is a frequency characteristic chart when the control is not performed.

FIG. 36 is an acoustic signal waveform diagram when the passive radiator of the audio reproduction device according to the embodiment is controlled.

FIG. 37 is an acoustic signal waveform chart when the control is not performed.

FIG. 38 is a block diagram showing a sound reproducing apparatus according to Embodiment 32 of the present invention.

FIG. 39 is a block diagram showing a sound reproducing apparatus according to Embodiment 33 of the present invention.

FIG. 40 is a block diagram showing a sound reproducing apparatus according to Embodiment 34 of the present invention.

FIG. 41 is a block diagram showing a sound reproducing apparatus according to Embodiment 35 of the present invention.

FIG. 42 is a block diagram showing a sound reproducing apparatus according to Embodiment 36 of the present invention.

FIG. 43 is a block diagram showing a sound reproducing apparatus according to Embodiment 37 of the present invention.

FIG. 44 is a block diagram showing a sound reproducing apparatus according to Embodiment 38 of the present invention.

FIG. 45 is a block diagram showing a sound reproducing apparatus according to Embodiment 39 of the present invention.

FIG. 46 is a block diagram showing a sound reproducing apparatus according to Embodiment 40 of the present invention.

FIG. 47 is a block diagram showing a sound reproducing apparatus according to embodiment 41 of the present invention;

FIG. 48 is a block diagram showing a sound reproducing apparatus according to embodiment 42 of the present invention.

FIG. 49 is a block diagram showing a sound reproducing apparatus according to embodiment 43 of the present invention.

FIG. 50 is an output characteristic diagram of a microphone of the sound reproducing device according to the embodiment.

FIG. 51 is a block diagram showing an audio reproducing apparatus according to embodiment 44 of the present invention.

FIG. 52 is a block diagram showing a sound reproducing apparatus according to Embodiment 45 of the present invention.

FIG. 53 is a block diagram showing a sound reproducing apparatus according to Embodiment 46 of the present invention.

FIG. 54 is a block diagram showing an audio reproducing apparatus according to embodiment 47 of the present invention.

FIG. 55 is a block diagram showing an audio reproducing apparatus according to embodiment 48 of the present invention.

FIG. 56 is a block diagram showing an audio reproducing apparatus according to embodiment 49 of the present invention.

FIG. 57 is a block diagram showing a sound reproducing apparatus according to Embodiment 50 of the present invention.

FIG. 58 is a block diagram showing a sound reproducing apparatus according to Embodiment 50 of the present invention.

FIG. 59 is a block diagram showing a sound reproducing apparatus according to Embodiment 51 of the present invention.

FIG. 60 is a block diagram showing a sound reproducing apparatus according to Embodiment 51 of the present invention.

FIG. 61 is a block diagram showing a sound reproducing apparatus according to Embodiment 52 of the present invention.

FIG. 62 is a block diagram showing a sound reproducing apparatus according to Embodiment 53 of the present invention.

FIG. 63 is a block diagram showing a sound reproducing apparatus according to Embodiment 53 of the present invention.

FIG. 64 is a block diagram showing a sound reproducing apparatus according to Embodiment 54 of the present invention.

FIG. 65 is a block diagram showing a sound reproducing apparatus according to Embodiment 54 of the present invention.

FIG. 66 is a block diagram showing a sound reproducing apparatus according to Embodiment 55 of the present invention.

FIG. 67 is a block diagram showing a sound reproducing apparatus according to Embodiment 56 of the present invention.

FIG. 68 is a block diagram showing a sound reproducing apparatus according to Embodiment 56 of the present invention.

FIG. 69 is a block diagram showing a sound reproducing apparatus according to Embodiment 57 of the present invention.

FIG. 70 is a block diagram showing an audio reproducing apparatus according to Embodiment 57 of the present invention.

FIG. 71 is a block diagram showing a sound reproducing apparatus according to Embodiment 58 of the present invention.

FIG. 72 is a block diagram showing a sound reproducing apparatus according to Embodiment 59 of the present invention.

FIG. 73 is a block diagram showing a sound reproducing apparatus according to Embodiment 59 of the present invention.

FIG. 74 is a block diagram showing a sound reproducing apparatus according to Embodiment 60 of the present invention.

FIG. 75 is a block diagram showing a sound reproducing apparatus according to Embodiment 60 of the present invention.

FIG. 76 is a block diagram showing a sound reproducing apparatus according to Embodiment 61 of the present invention.

FIG. 77 is a block diagram showing an audio reproducing apparatus according to Embodiment 62 of the present invention.

FIG. 78 is a block diagram showing a sound reproducing apparatus according to Embodiment 62 of the present invention.

FIG. 79 is a block diagram showing a sound reproducing device according to Embodiment 63 of the present invention.

FIG. 80 is a block diagram showing a sound reproducing apparatus according to Embodiment 63 of the present invention.

FIG. 81 is a block diagram showing an audio reproducing apparatus according to Embodiment 64 of the present invention.

FIG. 82 is a block diagram showing a sound reproducing apparatus according to Embodiment 65 of the present invention.

FIG. 83 is a block diagram showing a sound reproducing apparatus according to Embodiment 65 of the present invention.

FIG. 84 is a block diagram showing a sound reproducing apparatus according to Embodiment 66 of the present invention.

FIG. 85 is a block diagram showing a sound reproducing apparatus according to Embodiment 66 of the present invention.

FIG. 86 is a block diagram showing a configuration of a conventional sound reproducing device.

FIG. 87 is a block diagram showing a configuration of a sound reproducing apparatus using a speaker box incorporating a conventional passive radiator.

FIG. 88 is a characteristic diagram showing frequency characteristics according to a conventional example.

[Explanation of symbols]

1 Input terminal 2, 9, 12, 13 Subtractor 3, 26 Power amplifier 4, 4a, 4b, 4c, 4d, 4e Speaker 5, 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5
h, 5i, 27 microphone 5A first microphone 5B second microphone 6, 6a, 6b microphone amplifier 6A first microphone amplifier 6B second microphone amplifier 7, 7a, 7b, 10 adder / subtractor 7A first adder / subtractor 7B Second adder / subtracter 8, 8a, 8b Filter 11 High-pass filter 14a, 14b, 14c Filter 15a, 15b, 15c, 20, 23 Feedback circuit 16a, 16b, 16c, 16d, 16e Filter 17 Adder 18 Coil 19 , 30 Capacitor 21 Voltage Control Amplifier 22 Sound Quality Adjustment Filter 24 Level Detector 25 AC / DC Converter 28, 29, 31 Resistance 32 Output Terminal 33 Vibration Plate 34 Dust Cap 35 Lower Plate 36 Magnet 37 Upper Plate 38 Damper 39 Frame 40 Voice coil 41 Speaker box 41A Sealed space at rear 41B Sealed space at front 42 Speaker 42A Magnetic circuit 42B Voice coil 42C Dust cap 43 Passive radiator 44 Filter 44A First filter 44B Second filter 45 Phase shift circuit 46A first filter 46B second filter 47 inverting circuit 48 adder

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-206999 (JP, A) JP-A-58-63207 (JP, A) JP-A-5-300600 (JP, A) JP-A-49-49 46930 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04R 3/04 101

Claims (61)

(57) [Claims] 1. A subtracter having an input terminal connected thereto, a power amplifier for amplifying an output signal of the subtractor, a speaker for reproducing an output signal of the power amplifier, and detecting an acoustic output signal radiated from the speaker. A microphone, an amplifier for amplifying an acoustic output signal detected by the microphone, and an adder / subtractor for adding or subtracting an output signal of the microphone amplifier and an input signal of the power amplifier, and an output signal of the adder / subtractor. Is connected to the subtractor to form a feedback circuit. 2. The sound reproducing apparatus according to claim 1, wherein the adder / subtracter adds or subtracts an output signal of the microphone amplifier and an output signal of the power amplifier. 3. The sound reproducing apparatus according to claim 1, wherein a filter is provided between the microphone amplifier and the adder / subtractor. 4. A subtractor having an input terminal connected thereto, a power amplifier for amplifying an output signal of the subtractor, a speaker for reproducing an output signal of the power amplifier, and detecting an acoustic output signal radiated from the speaker. Microphone, a microphone amplifier for amplifying an acoustic output signal detected by the microphone, a first adder / subtractor for adding or subtracting an output signal of the microphone amplifier and an input signal of the power amplifier, and a high-pass filter The first adder / subtracter performs a subtraction process on the output signal of the microphone amplifier and an input signal of the power amplifier that have passed through the second adder / subtractor, and a second adder / subtractor performs the addition process on the subtraction process. And an audio reproducing apparatus in which a feedback circuit is formed by connecting an output signal of the second adder / subtractor to each of the subtractors. 5. A first adder / subtracter adds or subtracts an output signal of a microphone amplifier and an output signal of a power amplifier, and a second adder / subtractor outputs an output signal of the microphone amplifier passed through a high-pass filter. 5. The sound reproducing apparatus according to claim 4, wherein the first adder / subtractor performs a subtraction process on the output signal of the power amplifier when the addition process is performed, and performs an addition process on the subtraction process. 6. The filter according to claim 4, wherein a filter is provided on the output side of the microphone amplifier, and an output signal of the microphone amplifier is input to the first adder / subtractor and the high-pass filter through the filter. Sound reproduction device. 7. A first subtractor having an input terminal connected thereto, and a first subtractor connected in series to an output side of the first subtractor and branching its output signal to a minus terminal of the first subtractor. A connected second subtractor, a power amplifier for amplifying an output signal of the second subtractor, a speaker for reproducing the output signal of the power amplifier, and a microphone for detecting an acoustic output signal radiated from the speaker And a microphone amplifier for amplifying a sound output signal detected by the microphone, and the output signal of the microphone amplifier is connected to the second subtractor to constitute a feedback circuit. 8. The sound reproducing apparatus according to claim 7, wherein the signal connected to the minus terminal of the first subtractor is an output signal of a power amplifier. 9. The sound reproducing apparatus according to claim 7, wherein a filter is provided between an output of the microphone amplifier and a minus terminal of the second subtractor. 10. An adder / subtractor is provided between a microphone amplifier and a minus terminal of the second subtractor, and an output signal of the second subtracter is branched and connected to an input terminal of the adder / subtractor. Sound reproduction device. 11. The sound reproduction according to claim 8, wherein an adder / subtractor is provided between the microphone amplifier and the minus terminal of the second subtractor, and an output signal of the power amplifier is branched and connected to an input terminal of the adder / subtractor. apparatus. 12. The sound reproducing apparatus according to claim 10, wherein a filter is provided between an output of the microphone amplifier and an input of the adder / subtractor. 13. A first subtracter having an input terminal connected thereto,
A second subtractor connected in series to the output side of the first subtractor; amplifying the output of the second subtractor and branching the amplified output signal to reduce the output signal of the first subtractor. A power amplifier connected to the terminal, a speaker that reproduces an output signal of the power amplifier, a microphone that detects an acoustic output signal radiated from the speaker, a microphone amplifier that amplifies the acoustic output signal detected by the microphone, A sound reproducing apparatus comprising an adder / subtractor for adding or subtracting an output signal of the microphone amplifier and an input signal of the power amplifier, and connecting an output signal of the adder / subtractor to the second subtractor to constitute a feedback circuit. . 14. A signal connected to a minus terminal of a first subtractor is an input signal of a power amplifier, and an adder / subtracter adds or subtracts an output signal of a microphone amplifier and an output signal of the power amplifier. Claim 13
The sound reproducing device according to claim 1. 15. The sound reproducing apparatus according to claim 13, wherein a filter is provided between the microphone amplifier and the adder / subtractor. 16. A plurality of feedback circuits to which input terminals are connected, a plurality of filters respectively connected to the output sides of the plurality of feedback circuits, and an adder for adding signals passing through the plurality of filters, A power amplifier that amplifies the output signal of the adder, a plurality of speakers that respectively reproduce the output signal of the power amplifier through a passive filter, and a plurality of microphones that respectively detect acoustic output signals radiated from the plurality of speakers. And a sound reproducing device in which each sound output signal detected by the plurality of microphones is connected to the plurality of feedback circuits. 17. A subtractor having an input terminal connected thereto, a power amplifier for amplifying an output signal of the subtractor, a plurality of speakers for reproducing output signals of the power amplifier through respective passive filters, and a plurality of speakers. A plurality of microphones respectively detecting the radiated sound output signals, a plurality of microphone amplifiers respectively amplifying the sound output signals detected by the plurality of microphones, and a filter connected to the output side of the plurality of microphone amplifiers. A plurality of adder / subtractors for adding or subtracting the output signal of the microphone amplifier and the output signal of the subtractor, respectively, and each output of the plurality of adder / subtractors was connected to the subtractor to form a feedback circuit. Sound reproduction device. 18. A power amplifier for amplifying an input signal, a speaker for reproducing an output signal of the power amplifier, a microphone for detecting an audio output signal radiated from the speaker, and a sound output signal detected by the microphone. A microphone amplifier for amplifying, a feedback circuit for feeding back an output signal of the microphone amplifier to an input signal,
A detector connected to the output side of the feedback circuit and detecting the input voltage input to the power amplifier; a converter for converting the voltage detected by the detector into a DC voltage; A sound reproducing apparatus comprising: a voltage control amplifier for amplifying an input signal by using a voltage control amplifier; and a sound quality adjustment filter connected to an output side of the voltage control amplifier, and connecting a signal passed through the sound quality adjustment filter to the feedback circuit. 19. A BT power amplifier for amplifying an input signal
19. The sound reproducing apparatus according to claim 1, wherein an L connection is made, only an output of a DC component is extracted from an output signal of the power amplifier, and the extracted DC voltage is connected to a microphone. 20. The sound reproducing apparatus according to claim 1, wherein a microphone for detecting an acoustic output signal radiated from the speaker is arranged on a front surface of a diaphragm of the speaker. 21. The sound reproducing apparatus according to claim 1, wherein a microphone for detecting an acoustic output signal radiated from the speaker is arranged on an upper surface of a central portion of a magnetic circuit of the speaker. 22. The sound according to any one of claims 1 to 19, wherein a microphone for detecting an acoustic output signal radiated from the speaker is arranged at a lowermost end of a through hole provided in a center portion of a magnetic circuit of the speaker. Playback device. 23. The sound reproducing apparatus according to claim 1, wherein a microphone for detecting a sound output signal radiated from the speaker is disposed inside a magnetic circuit of the speaker. 24. The sound reproducing apparatus according to claim 1, wherein a microphone for detecting a sound output signal radiated from the speaker is arranged between a magnetic circuit of the speaker and a damper. 25. The sound reproducing apparatus according to claim 1, wherein a microphone for detecting a sound output signal radiated from the speaker is disposed between an inner surface of the frame of the speaker and the diaphragm. 26. A speaker for reproducing an output signal of a subtracter to which an input terminal is connected via a power amplifier is internally connected, a closed space is formed before and after the speaker, and a passive radiator is connected to an opening. A speaker box, a microphone arranged on the upper surface of a magnetic circuit of the speaker for detecting an acoustic output signal emitted from the speaker, a microphone amplifier for amplifying the acoustic output signal detected by the microphone, and an output of the microphone amplifier A sound reproducing apparatus comprising an adder / subtractor for adding or subtracting a signal and an input signal of the power amplifier, and connecting an output signal of the adder / subtractor to the subtractor to form a feedback circuit. 27. The sound reproducing apparatus according to claim 26, wherein a filter is provided between the microphone amplifier and the adder / subtractor. 28. The sound reproducing apparatus according to claim 26, wherein a phase shift circuit is provided between the microphone amplifier and the adder / subtractor. 29. The sound reproducing apparatus according to claim 26, wherein a filter and a phase shift circuit are provided between the microphone amplifier and the adder / subtractor. 30. The output of a microphone amplifier is connected to a first filter and a second filter having different characteristics, and is branched. An output of the first filter and an output of the second filter are passed through an inverting circuit. 27. The output of the adder is connected to an adder, and the output of the adder is connected to an adder / subtractor.
The sound reproducing device according to claim 1. 31. An output of a microphone amplifier is connected to a first filter and a second filter having different characteristics, and branched, and a phase shift circuit is provided between the output of the first filter and the output of the second filter. 27. The output passed through is connected to an adder, and the output of the adder is connected to an adder / subtractor.
The sound reproducing device according to claim 1. 32. The sound reproducing apparatus according to claim 26, wherein a microphone for detecting an acoustic output signal radiated from the speaker is disposed in a closed space on a rear surface of the speaker. 33. The sound reproducing apparatus according to claim 32, wherein a filter is provided between the microphone amplifier and the adder / subtractor. 34. The sound reproducing apparatus according to claim 32, wherein a phase shift circuit is provided between the microphone amplifier and the adder / subtractor. 35. The sound reproducing apparatus according to claim 32, wherein a filter and a phase shift circuit are provided between the microphone amplifier and the adder / subtractor. 36. An output of the microphone amplifier is connected to a first filter and a second filter having different characteristics, and is branched. An output of the first filter and an output of the second filter are passed through an inversion circuit. 33. The output of the adder is connected to an adder, and the output of the adder is connected to an adder / subtractor.
The sound reproducing device according to claim 1. 37. An output of the microphone amplifier is connected to a first filter and a second filter having different characteristics, and branched, and a phase shift circuit is provided between the output of the first filter and the output of the second filter. 33. The output passed through is connected to an adder, and the output of the adder is connected to an adder / subtractor.
The sound reproducing device according to claim 1. 38. The sound reproducing apparatus according to claim 26, wherein a microphone for detecting a sound output signal radiated from the speaker is disposed in a closed space in front of the speaker. 39. The sound reproducing apparatus according to claim 38, wherein a filter is provided between the microphone amplifier and the adder / subtractor. 40. The sound reproducing apparatus according to claim 38, wherein a phase shift circuit is provided between the microphone amplifier and the adder / subtractor. 41. The sound reproducing apparatus according to claim 38, wherein a filter and a phase shift circuit are provided between the microphone amplifier and the adder / subtracter. 42. The output of the microphone amplifier is connected to a first filter and a second filter having different characteristics, and branched, and the output of the first filter and the output of the second filter are passed through an inverting circuit. 38. An output of the adder is connected to an adder, and an output of the adder is connected to an adder / subtractor.
The sound reproducing device according to claim 1. 43. An output of the microphone amplifier is connected to a first filter and a second filter having different characteristics and branched, and a phase shift circuit is provided between the output of the first filter and the output of the second filter. 38. The output of the adder is connected to an adder, and the output of the adder is connected to an adder / subtractor.
The sound reproducing device according to claim 1. 44. A speaker for reproducing an output signal of a subtracter to which an input terminal is connected via a power amplifier is coupled inside, a closed space is formed before and after the speaker, and a passive radiator is coupled to an opening. A speaker box, first and second microphones respectively disposed in a closed space on an upper surface and a rear surface of a magnetic circuit of the speaker for detecting an acoustic output signal radiated from the speaker; First and second microphone amplifiers for respectively amplifying acoustic output signals detected by the microphone, a second adder / subtractor for adding or subtracting the output signals of the first and second microphone amplifiers, and the second A first adder / subtractor for adding or subtracting the output signal of the adder / subtractor and the input signal of the power amplifier; An audio reproducing apparatus in which a feedback circuit is formed by connecting an output signal of a subtractor to the subtractor. 45. The sound reproducing apparatus according to claim 44, wherein a filter is provided between one of the first microphone amplifier and the second microphone amplifier and the second adder / subtracter. 46. The sound reproducing apparatus according to claim 44, wherein a phase shift circuit is provided between one of the first microphone amplifier and the second microphone amplifier and the second adder / subtracter. 47. The sound reproducing apparatus according to claim 44, wherein a filter is provided between each of the first microphone amplifier and the second microphone amplifier and the second adder / subtracter. 48. A filter provided between one of the first microphone amplifier and the second adder / subtractor or between the second microphone amplifier and the second adder / subtractor, and a phase shift circuit on the other. Item 45. The sound reproducing device according to Item 44. 49. A filter and a phase shift circuit are provided between one of the first microphone amplifier and the second adder / subtractor or between the second microphone amplifier and the second adder / subtractor, and the other is provided with a filter. The sound reproducing device according to claim 44. 50. A speaker for reproducing an output signal of a subtracter to which an input terminal is connected via a power amplifier is internally connected, a closed space is formed before and after the speaker, and a passive radiator is connected to an opening. A speaker box, first and second microphones respectively disposed in a closed space on the upper surface and the front surface of a magnetic circuit of the speaker for detecting an acoustic output signal radiated from the speaker, and the first and second microphones. First and second microphone amplifiers for respectively amplifying acoustic output signals detected by the microphone, a second adder / subtractor for adding or subtracting output signals of the first and second microphone amplifiers, and a second adder / subtractor A first adder / subtractor for adding or subtracting the output signal of the adder / subtractor and the input signal of the power amplifier; An audio reproducing apparatus in which a feedback circuit is formed by connecting an output signal of a subtractor to the subtractor. 51. The sound reproducing apparatus according to claim 50, wherein a filter is provided between one of the first microphone amplifier and the second microphone amplifier and the second adder / subtracter. 52. The sound reproducing apparatus according to claim 50, wherein a phase shift circuit is provided between one of the first microphone amplifier and the second microphone amplifier and the second adder / subtracter. 53. The sound reproducing apparatus according to claim 50, wherein a filter is provided between each of the first microphone amplifier and the second microphone amplifier and the second adder / subtractor. 54. A filter provided between one of the first microphone amplifier and the second adder / subtractor or between the second microphone amplifier and the second adder / subtractor, and a phase shift circuit on the other. Item 50. The sound reproducing device according to Item 50. 55. A filter and a phase shift circuit are provided between one of the first microphone amplifier and the second adder / subtractor or between the second microphone amplifier and the second adder / subtractor, and the other is provided with a filter. 51. The sound reproducing device according to claim 50. 56. A speaker for reproducing an output signal of a subtracter to which an input terminal is connected via a power amplifier is internally connected, a closed space is formed before and after the speaker, and a passive radiator is connected to an opening. A speaker box, first and second microphones respectively disposed in a closed space portion on a rear surface of the speaker and in a closed space portion on a front surface of the speaker for detecting an acoustic output signal radiated from the speaker; First and second microphone amplifiers for amplifying the acoustic output signals detected by the two microphones, a second adder / subtracter for adding or subtracting the output signals of the first and second microphone amplifiers; And a first adder / subtractor for adding or subtracting the output signal of the second adder / subtractor and the input signal of the power amplifier. An audio reproducing apparatus in which an output signal of an adder / subtractor is connected to the subtractor to form a feedback circuit. 57. The sound reproducing apparatus according to claim 56, wherein a filter is provided between one of the first microphone amplifier and the second microphone amplifier and the second adder / subtractor. 58. The sound reproducing apparatus according to claim 56, wherein a phase shift circuit is provided between one of the first microphone amplifier and the second microphone amplifier and the second adder / subtracter. 59. The sound reproducing apparatus according to claim 56, wherein a filter is provided between each of the first microphone amplifier and the second microphone amplifier and the second adder / subtractor. A filter is provided between one of the first microphone amplifier and the second adder / subtractor or between the second microphone amplifier and the second adder / subtractor, and the other is provided with a phase shift circuit. Item 60. The sound reproducing device according to Item 56. 61. A filter and a phase shift circuit are provided between one of the first microphone amplifier and the second adder / subtractor or between the second microphone amplifier and the second adder / subtractor, and the other is provided with a filter. The sound reproducing device according to claim 56.