JP3423695B2 - Speaker 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 speaker device in which a plurality of amplification means such as a class B power amplifier and a driving means such as a voice coil are configured to drive a load such as a speaker in parallel. .

[0002]

2. Description of the Related Art Generally, a multi-voice coil speaker system in which one speaker cone is vibrated by a plurality of voice coils includes a voice coil into which a low tone of an L signal of a stereo signal is input and a voice coil into which a low tone of an R signal is input. It is used for a so-called 3D type central speaker that drives one speaker cone with two voice coils of, and a voice coil is connected to each of a plurality of amplifiers to drive one speaker cone and Used to increase overall maximum output.

The reason why this multi-voice coil speaker system is used to increase the maximum output of the entire amplifier driving the speaker is as follows. The maximum output value P0 (MAX) of a class B power amplifier, which is a commonly used speaker driving power amplifier, is P0 (MAX) = Vcc ² / where Vcc is the power supply voltage and RL is the impedance of the voice coil. 8RL Equation (1) is obtained. Therefore, in order to increase the value of P0 (MAX), increase the power supply voltage Vcc or the impedance R of the voice coil.
Either method of lowering L is necessary. However, it is difficult to increase the battery power supply voltage in order to increase Vcc in car audio equipment, etc.
It is not easy to lower L because of the manufacturing of the voice coil or the restriction of wiring impedance. Therefore, a plurality of B
A multi-voice coil speaker system using parallel class power amplifiers is used.

FIG. 14 is a block diagram showing a first conventional multi-voice coil speaker system. In this figure, 1a and 1b are class B power amplifiers for amplifying an input signal A to drive a multi-voice coil speaker 2 (described later), 2 are two voice coils 2a and 2b, and one speaker cone 3 (described later). It is a multi-voice coil speaker that vibrates. The input signal A is input in parallel to the class B power amplifiers 1a and 1b, and each output is a voice coil 2
It is input to a and 2b. Reference numeral 3 is a speaker cone that functions as a diaphragm driven by the voice coils 2a and 2b.

Next, the relationship between the output of the class B power amplifier and the internal loss will be described. Here, if the output of the class B power amplifier is P0 and the internal loss is PC, the relation between them is PC = (Vcc / 2) x (P0 / RL) ^1/2 -P0 (2) Has been. Therefore, if one class B power amplifier is used and the class B power amplifier is driving the speaker with the output P0A, and the internal loss at this time is PCA, then PCA = (Vcc / 2) × (P0A / RL) ^1/2 −P0A (3). On the other hand, when two class B power amplifiers are used, each class B power amplifier must take half of the output POA in order to obtain the output P0A with these two class B power amplifiers. Internal loss PCB of class B power amplifier
From the equation (2), PCB = (Vcc / 2) × {(P0A / 2) / RL} ¹ / 2- (P0A / 2) (4) Therefore, the total internal loss 2PCB of the two class B power amplifiers is 2PCB = 2 × [(Vcc / 2) × {(P0A / 2) / RL} ^1/2 − (P0A / 2)] = (Vcc / 2) × 2 ^1/2 × (P0A / RL) ^1/2 −P0A (5) Equation becomes, and when the same output P0A is output by comparing Equation (5) and Equation (3), It can be seen that the speaker system having two class B power amplifiers has a larger internal loss than the speaker system having one class B power amplifier. Further, FIG. 15 is a characteristic diagram of a class B power amplifier in which the horizontal axis represents the output value and the vertical axis represents the internal loss. The curve A in FIG. 15 shows the output and the internal loss of one class B power amplifier. The curve A shows the relationship between the total output and the total internal loss of the two class B power amplifiers. From this figure, it can be seen that the speaker system with two class B power amplifiers has a larger internal loss than the speaker system with one class B power amplifier.

FIG. 16 is a circuit diagram showing a class B power amplifier. In this figure, the input signal to the class B power amplifier is input from the input 1d and is input to the base of the transistor 1e in the first stage. This input signal is amplified by the transistor 1e, and the collector load resistance 1 of the transistor 1e is amplified.
It is taken out from f and added to the base of the next-stage transistor 1g. The input signal is further amplified and transistor 1g
Is taken out from the collector load resistance 1h and input to the push-pull driver circuit constituted by the final stage transistors 1i and 1j. The diodes 1k and 1L are for giving the base bias of the transistors 1i and 1j. Since the connection point between the emitters of the transistors 1i and 1j is biased to the power source Vcc by the voltage of Vcc / 2, the voltage of Vcc / 2 is applied to both ends of the output capacitor 1c.

If a signal is applied to the input terminal 1d and the bases of the transistors 1i and 1j are swung in the positive direction, the transistor 1i turns on and the output capacitor 1
A current is pushed out from the + terminal to the-terminal of c, and a speaker drive current flows through the voice coil 2a from the hot side (indicated by + in the figure) to the ground side (indicated by-in the figure). On the contrary, when the bases of the transistors 1i and 1j are swung in the negative direction, the transistor 1j is turned on to draw a current from the − terminal of the output capacitor 1c in the + terminal direction, and the voice coil 2a is turned from the ground side to the hot side. The speaker drive current flows to.

Thus, in order to prevent the output capacitor 1c from passing a direct current to the voice coil 2a in the class B power amplifier 1a, it is possible to pass a current in the forward and reverse phase directions to the voice coil 2a. It is provided to do so.

FIG. 17 is an explanatory diagram showing a transient current flowing through the class B power amplifier. Here, class B power amplifier 1
Considering the transient state when the power source voltage Vcc in a is turned on and off, when the power source Vcc is supplied to the class B power amplifier 1a, the capacitor 1c is charged, so that FIG.
A transient current as shown in (4) flows into the voice coil 2a. When the power supply Vcc of the class B power amplifier 1a is turned off, the transient current as shown in FIG. 17B flows in the reverse direction to the voice coil 2a due to the discharge of the capacitor 1c. In this way, when the power of the class B power amplifier is turned on and off, a transient current flows in the voice coil 2a, and this transient current is input to the speaker, and shock noise causing discomfort for the user is emitted from the speaker.

FIG. 18 is a configuration diagram showing a second conventional multi-voice coil speaker system, and FIG. 19 is a relational diagram showing a relation between internal loss and output in a plurality of class B power amplifiers as a whole. In FIG. 19, the curve a shows the characteristic per class B power amplifier, and the curve a shows the characteristic as the whole class B power amplifier. In these figures, 5a, 5b, 5c and 5d are class B power amplifiers having the same characteristics as the class B power amplifiers 1a and 1b in the first conventional multi-voice coil speaker system. 5b, 5c, and 5d amplify the input signal, and the voice coils 6a, 6b, and 6 respectively.
It outputs to c and 6d, and drives one speaker cone 7. In the multi-voice coil speaker system configured as above, the characteristics of the entire class B power amplifier are shown in FIG.
Since the curve A of FIG. 9 is obtained, as can be seen by comparing the curve A and the curve A, the second conventional multi-voice coil speaker system is similar to the first conventional multi-voice coil speaker system. In addition, the internal loss increases and the efficiency of driving the speaker decreases.

[0011]

Since the first conventional multi-voice coil speaker system or the second conventional multi-voice coil speaker system is configured as described above, it is driven by one class B power amplifier. You can increase the power to drive the speaker more than if
Since the internal loss increases, the efficiency of driving the speaker decreases and the amount of heat generated increases.

Further, when the power of the class B power amplifier is turned on and off, a transient current transiently flows through the voice coil, which is emitted as shock noise from the speaker.

The present invention has been made to solve the above problems, and an object thereof is to obtain a speaker device in which shock noise is not generated.

[0014]

A speaker device according to the present invention includes a pair of amplifying means having the same characteristics for amplifying one input signal, one speaker driven by the pair of amplifying means, and the pair of amplifying means. It is provided with a phase inverting means provided before and after one of the amplifying means.

Also, a first amplifying means for inputting and amplifying the input signal, a first voice coil connected to the first amplifying means for driving a speaker cone, and the input signal being inputted through the phase inverting means. And a second voice coil which is connected to the second amplifying means and drives the speaker cone, and which is connected to the first amplifier. The polarity of the wiring with the first voice coil is connected in an opposite phase to the polarity of the wiring with the second amplifier and the second voice coil connected thereto.

Further, a first amplifying means for inputting and amplifying the input signal, a first voice coil connected to the first amplifying means for driving the speaker cone, and the input signal being inputted through the phase inverting means. And a second voice coil which is connected to the second amplifying means and drives the speaker cone, and which is connected to the first amplifier. The polarity of the wiring with the first voice coil is connected in an opposite phase to the polarity of the wiring with the second amplifier and the second voice coil connected thereto, and the polarity with respect to the input signal is The driving forces of the speaker cones generated in the two voice coils are in the same direction.

[0017]

In the speaker device according to the present invention, the noise generated from the inside of one amplifying means cancels out the noise generated from the inside of the other amplifying means.

[0018]

EXAMPLES Further, the examples are summarized as follows. The speaker device according to this embodiment includes a signal level limiting means for limiting and outputting an input signal to a predetermined signal level or less, a subtraction calculating means for outputting a difference between an input signal and an output of the signal level limiting means, and a signal. It is driven by a first amplifying means for amplifying the output of the level limiting means, a second amplifying means for amplifying the output of the subtraction calculating means, and an output of the first amplifying means and an output of the second amplifying means. One speaker is provided.

With this configuration, the input signal below the predetermined signal level is amplified by the first amplifying means, and the difference between the input signal and the input signal below the predetermined level is the second.
Is amplified by the amplifying means and the output of the first amplifying means and the output of the second amplifying means are combined to drive one speaker. The first amplifying means and the second amplifying means The internal loss of the speaker can be reduced and the efficiency of driving the speaker can be improved.

Further, it has a plurality of signal level limiting means for limiting and outputting the signal level of the input signal and a plurality of subtraction calculating means for outputting the difference between the signal levels before and after the signal level limiting means. Signal level range dividing means for dividing one input signal into a plurality of signal level areas, a plurality of amplifying means for amplifying each of the plurality of signal level areas, and one speaker driven by the outputs of the plurality of amplifying means. And are provided.

With this configuration, one input signal is divided into a plurality of signal level areas by the signal level area dividing means, each of which is amplified to drive one speaker, and a plurality of amplifying means. It is possible to reduce the internal loss in, and improve the efficiency of driving one speaker.

Further, a pair of amplifying means having the same characteristics for amplifying one input signal, one speaker driven by the pair of amplifying means, and one of the pair of amplifying means before and after the amplifying means. And the phase inversion means provided in and. With this configuration, the noise generated from the inside of one amplifying unit cancels out the noise generated from the inside of the other amplifying unit, so that the noise generated in the amplifying unit can be reduced.

Further, low-frequency attenuation means is provided between the signal level limiting means and the subtraction calculation means. With this configuration, since the signal in which the low frequency range is attenuated is input from the signal level limiting means to the subtraction operation means, the output of the subtraction operation means increases the low frequency range, and particularly the low frequency range. When used in a place where noise is generated, the low range can be supplemented.

Further, a first high frequency attenuation means for attenuating a high frequency band of a predetermined value or more of the input signal is provided in a stage preceding the subtraction calculation means,
Provided between the subtraction calculation means and the signal level limiting means,
The second high frequency attenuation means having the same frequency characteristic as the first high frequency attenuation means is provided between the subtraction calculation means and the signal level limiting means. By configuring in this way,
The noise of the high frequency component which is generated from the inside of the signal level limiting means and is equal to or higher than a predetermined value is not output from the subtraction operation means. Therefore, the second amplifying means does not operate with a high frequency component equal to or higher than a predetermined value, and it is possible to reduce internal loss and improve the efficiency of driving the speaker.

The amplifying apparatus according to this embodiment includes signal level limiting means for limiting the signal level of one input signal, subtraction computing means for outputting the difference between the input signal and the output of the signal level limiting means, and the signal. First to amplify the output of the level limiting means
Amplifying means, second amplifying means for amplifying the output of the subtraction calculating means, and output signal output means for outputting one output signal by the output of the first amplifying means and the output of the second amplifying means. Is provided. By configuring in this way,
The input signal below the limited signal level is amplified by the first amplifying means, and the difference between the input signal and the input signal below the limited signal level is amplified by the second amplifying means, The combined output of the output and the output of the second amplifying means is output as one output signal.
Therefore, it is possible to reduce internal loss in the first amplifying means and the second amplifying means and improve efficiency.

The load driving device according to this embodiment outputs a signal level limiting means for limiting and outputting one input signal to a predetermined signal level or less, and a difference between the one input signal and the output of the signal level limiting means. The ratio between the increase in internal loss and the increase in driving force (increase in internal loss / Increased driving force)
Is driven by the first drive means and the second drive means, the first drive means having the characteristic of decreasing as the drive force increases, the second drive means operating by the output of the subtraction calculation means, And a load. With this configuration, the first driving means to which the input signal below the predetermined signal level is inputted and the second driving means to which the difference between the input signal and the input signal below the predetermined signal level is inputted. It drives one load. Therefore, it is possible to reduce the internal loss in the first driving unit and the second driving unit and improve the efficiency of driving the load.

Example 1. 1 is a block diagram showing a first embodiment of the present invention, and FIG. 2 is a block diagram showing a gain limiting means.
11a and 11b are class B power amplifiers having the same characteristics. 12 is two voice coils 12a and 12b and this 2
A multi-voice coil speaker having one speaker cone 12c vibrated by two voice coils 12a and 12b, 13 is a gain limiting means for limiting the output to a certain voltage or less by limiting the gain, and 14 is 2 A signal having a voltage value obtained by subtracting the voltage value of the signal input to the input terminal 100 from the voltage value of the signal input to the input terminal 101, which has two input terminals 100 and 101, is output terminal 102.
It is a subtraction calculation means for outputting from.

Here, the gain limiting means 13 has an input terminal B.
From the input terminal 100 of the subtraction calculation means 14 and the class B power amplifier 11a, and outputs the signal v2 whose gain is limited. The subtraction calculation means 14 has an input terminal 100.
Signal v2 is input to the input terminal 101, and the signal v1 is input to the input terminal 101, and the signal v3 is output from the output terminal 102 to the class B power amplifier 11b. The class B power amplifier 11a outputs to the voice coil 12a, and the class B power amplifier 11b outputs to the voice coil 12b.

FIG. 2 is a block diagram showing the gain limiting means 13 in FIG. In this figure, a signal v1 is input to the input, passes through a VCA (voltage controlled variable gain amplifier) 13a,
It is output as signal v2. The gain of this VCA 13a is controlled as follows. The output of the VCA 13a is level-detected by the envelope detector 13b and the rectifier 13c, and the level-detected level and the reference level output unit 13 are detected.
The comparator 13e compares the reference level output from d with the reference level. If the output of the rectifier 13c is larger than the reference level output section 13d, the control voltage generation section 13f outputs VCA.
A control voltage is generated to reduce the gain of 13a, and the VCA 13a is feedback-controlled so that the output of the reference level output unit 13d ≧ the output of the rectifier 13c. As a result, the output of the gain limiting circuit 13 is determined below the reference level,
A so-called "limiter" operation is performed in which the signal v2 does not become an output higher than the reference level.

FIG. 3 is a block diagram showing the subtraction calculation means 14 in FIG. Reference numeral 14a is an operational amplifier, 14b is a resistor having a resistance value R, which are connected as shown in FIG.
It constitutes a differential amplifier circuit. Therefore, the subtraction calculation means 14 subtracts the voltage value of the signal v2 from the voltage value of the signal v1 from the signal v2 input to the input terminal 100 and the signal v1 input to the input terminal 101 (v1-v2). A signal v3 having a voltage value is output.

Next, the operation will be described. FIG. 4 is a diagram showing the relationship between the input / output voltage of the subtraction calculation means 14 and the voltage value of the signal v1, and FIG. 4 (a) is the relationship between the voltage value at the input terminal 101 and the voltage value of the signal v1. 4b, which is a diagram showing
Is a diagram showing the relationship between the voltage value of the signal v2 and the voltage value of the signal v1, and FIG. 4 (c) is a diagram showing the relationship between the voltage value of the signal v3 and the voltage value of the signal v1. Here, the signal v1 is input to the gain limiting means 13 and the input terminal 101 of the subtraction calculating means 14. Therefore, FIG.
As shown in, the voltage value of the signal v1 is directly input terminal 10
The voltage value is 1. On the other hand, since the signal v2 input to the input terminal 100 of the subtraction calculation means 14 is the output of the gain limiting means 13 that does not output a signal of a certain level or higher, the signals v2 and v1 are shown in FIG. The relationship is as shown. Therefore, the signals v3 and v1 of the subtraction calculation means 14
As for the relationship with, the subtraction calculation means 14 outputs the voltage of the difference between the voltage value of the signal v1 and the voltage value of the signal v2.
FIG. 4B is subtracted from FIG.
The relationship is as shown in (c).

As shown in FIG. 4, when the signal v1 is small, the signal v3 is not output, but when the signal v1 reaches a certain level, the signal v3 increases as the signal v1 increases.
Will increase. That is, when the signal v1 increases, the pair of class B power amplifiers 11a and 11b initially operate only the class B power amplifier 11a, and when the signal v1 reaches a certain value, the class B power amplifier 11a. Holds its output and operates so that the class B power amplifier 11b outputs for the first time based on the signal v3 corresponding to the increment of the signal v1. Here, as shown in FIG. 4, the sum of the signal v2 and the signal v3 is the signal v
Therefore, the speaker cone 12c is driven similarly to the case where the speaker cone 12c is driven by amplifying the signal v1.

FIG. 5 is a diagram showing the relationship between the output of the class B power amplifier and the internal loss. Here, the internal loss with respect to the output in the first embodiment will be described. In the first embodiment, the signal level at which the gain limiting means 13 functions and the output is limited is set to a value immediately before the output of the class B power amplifier 11a starts to be distorted, and the relationship between the output power and the internal loss at this time is shown in FIG. "Point a" shown in 5. This point is generally the region where the internal loss decreases conversely with the increase in the output as is clear from FIG. 5, so that the ratio of (internal loss / output) is small and the driving efficiency is good. It can be said that it is a point.

By the way, as described above, in this embodiment, the two class B power amplifiers are first classified into the class B power amplifier 11a.
Since only the class B power amplifier 11b operates and the output reaches a certain level, the class B power amplifier 11b operates so as to output the subsequent increment. Therefore, the total output vs. the total internal loss characteristics of the class B power amplifiers 11a and 11b are as follows. At the point “point a” in FIG. 5 where the driving efficiency of the class B power amplifier 11a is high, the output vs. internal loss characteristic of the class B power amplifier 11b is connected, and the characteristic is shown by the curve c in FIG. Here, the curve a in FIG. 5 is the characteristic in parallel driving of two class B power amplifiers shown in FIG. 15 of the first conventional example. In FIG. 5, since the curve c is plotted on the lower side with respect to the curve a, the driving method according to the present embodiment is a method having a high driving efficiency with less internal loss as compared with the first conventional example. I understand that. Needless to say, the heat generated from the class B power amplifier is reduced if the internal loss is small.

Example 2. FIG. 6 is a configuration diagram showing a multi-voice coil speaker system according to a second embodiment in which four class-B power amplifiers drive a multi-voice coil speaker having four voice coils. 16 is a multi-voice coil speaker, and 16a, 16b, 16
Reference numerals c and 16d are the first, second, third and fourth voice coils, respectively, and 17a, 17b, 17c and 17d are class B power amplifiers for driving them. The gain limiting means 18a, 18b and 18c similar to the gain limiting means in the first embodiment are provided in the preceding stage of each class B power amplifier, and the preceding stages of the gain limiting means 18b and 18c are similar to those in the first embodiment. Subtraction operation means 19 and 20 are provided, and a subtraction operation means 21 similar to the subtraction operation means in the first embodiment is provided in the preceding stage of the class B power amplifier 17d.
Are connected. The subtraction calculation means 19, 20, 21 have gain limiting means 18a, 18b, at their two input terminals.
A signal input to 18c and gain limiting means 18a, 18
The signals output from b and 18c are input, and signals having a voltage (voltage of input signal-voltage of output signal) of the gain limiting means 18a, 18b, and 18c are output.

Next, the operation will be described. First, when the input signal C is input, the input signal C is input to the gain limiting means 18
The class B power amplifier 17a is driven via a. here,
Since the gain limiting means 18a is the same as that of the first embodiment, when the signal input is small, its input and output are the same signal. Therefore, since the subtraction calculation means 19 does not output a signal, the class B power amplifier 17b is not driven. Similarly, the class B power amplifiers 17c and 17d are not driven. Next, when the input signal increases and the gain limiting means 18a operates, the class B power amplifier 17b outputs an output equal to or larger than a predetermined input value, as in the first embodiment. Here, when the input signal further increases, the gain limiting means 18b starts operating, and the class B power amplifier 17c is similarly driven. Hereinafter, the same operation is performed for the class B power amplifier 17d.

FIG. 7 is a diagram showing the relationship between the output and the internal loss in the class B power amplifier. As shown in FIG. 7, four class B power amplifiers 17a, 1
7b, 17c, and 17d start operation in order. Therefore, according to the same concept as in the case of the first embodiment including two amplifiers, the relationship between the total output and the total internal loss of these four class B power amplifiers is as follows: The relationship shown in the curve A in FIG. 7 is obtained by connecting the loss curves to each other at the output point where each gain limiting means operates. Curve A in FIG. 7 is a curve of total output versus internal loss when four amplifiers are driven in parallel. It can be confirmed from the comparison between curves A and B in FIG. 7 that the configuration according to this embodiment is a driving method with less internal loss and higher efficiency.

In the second embodiment, the configuration operation when the number of voice coils is 4 is described, but the similar configuration is not limited to the case where the number of voice coils is only 4, but a multi-voice coil speaker having a plurality of voice coils. Of course, the same effect can be obtained for the system.

Further, in the gain limiting means in each of the above embodiments, the reference level output from the reference level output section is changed according to the frequency of the input signal, thereby performing the gain limiting according to the frequency characteristic, It is also possible to eliminate audible unnaturalness.

Example 3. Further, the combination of the drive target and the drive means is not limited to the combination of the multi-voice coil speaker and the class B power amplifier, and is used in a motor drive device that drives one load by a plurality of motors as shown in the third embodiment. It is possible. FIG. 8 is an explanatory view showing the third embodiment of the present invention. 20a-20
Reference numeral c is a drive motor having a region where the ratio of the increase in output to the increase in internal loss decreases. Reference numerals 21a to 21c are transistors, and 22 is a power supply supplied to the motor via the transistor 21. 23a and 23b function as so-called limiters that limit the output to a certain voltage (the voltage at which the input to the motors 20a to 20c becomes a region in which the ratio of the increase in output and the increase in internal loss decreases) and below. The gain limiting means 23a,
Reference numeral 23b has the same configuration as the gain limiting means 13 in the first embodiment. Reference numerals 24a and 24b denote subtraction calculation means for outputting a difference between two inputs, and the subtraction calculation means 24a and 24b.
Has the same configuration as the subtraction calculation means 14 in the first embodiment. Reference numeral 25 is a motor control voltage input to which a motor control voltage is input from the outside. 26a to 26c are motors 20a to
A belt pulley that transmits the rotational force of 20c to the belt 27, and the load 28 is driven by the belt 27.

Next, the operation will be described. The motor control voltage input from the motor control voltage input 25 from an external control device or the like is limited to a certain voltage or less by the first gain limiting means 23a and is input to the base of the first transistor 21a. Further, the motor control voltage and the output of the first gain limiting means 23a are input to the first subtraction calculating means 24a. A value obtained by subtracting the output of the first gain limiting means 23a from the motor control voltage is output from the first subtraction calculating means 24a. Similarly to the first gain limiting means 23a, the second gain limiting means 23b limits the output of the first subtraction calculating means 24b to a certain voltage or less, and the second transistor 2
Output to the base of 1b. Also, the first subtraction calculation means 2
The output of 4a and the output of the second gain limiting means 23b are the second
Is input to the subtraction calculation means 24b, and the difference between these inputs is output to the base of the third transistor 21c. Here, the transistors 21a to 21c output the input from the power supply 22 to the motors 20a to 20c based on the input to the base. This output causes the motors 20a to 20c to rotate the belt pulleys 26a to 26c and drive the load 28 via the belt 27. Example 3 configured in this way
In the above, it is possible to drive the load 28 with a plurality of motors while reducing the internal loss.

Further, although the motor is used in the third embodiment, it may be any one that can generate a driving force of an engine of an internal combustion engine or the like.

Example 4. FIG. 9 is a configuration diagram showing the fourth embodiment, and FIG. 10 is a circuit diagram showing the phase inverting means. 51a
And 51b are class B power amplifiers having the same characteristics, 52 is a multi-voice coil speaker having two voice coils 52a and 52b, and 53 is a phase inverting means as shown in FIG. The phase inverting means 53 is connected in front of the class B power amplifier 51b, and the input signal D is input to the phase inverting means 53 and the class B power amplifier 51a. On the other hand, the class B power amplifiers 51a and 51b are connected to the voice coils 52a and 52b, respectively, and the polarity of the wiring between the class B power amplifier 51b and the voice coil 52b connected thereto is the same as that of the class B power amplifier 51a. Are connected to the voice coil 52a connected in the opposite phase with respect to the polarity of the wiring. The phase inverting means 53 is composed of, for example, a general operational amplifier circuit 53 as shown in FIG. In FIG. 10, 53a is an operational amplifier, 53b is a resistor, and one is an input terminal of the circuit and the inverting input terminal of the operational amplifier 53a (in the figure-
, And the other is the operational amplifier 53.
It is inserted between the inverting input terminal and the output terminal of a. Since these two resistors have the same value, the operational amplifier circuit 53 outputs a signal whose amplitude is the same and whose phase is inverted.
Function as.

Next, the operation will be described. Now, assuming that the power is turned on and the apparatus is in a sufficiently stable state, the input signal D is input to the class B power amplifier 51a in a positive phase, but the phase inverting means 53 is included in the class B power amplifier 51b. Since the signals are input in the opposite phase via the, the class B power amplifier 51a and the class B power amplifier 51 are applied to the input signal D.
They operate in opposite phases to b. Therefore, the output of the class B power amplifier 51b has a phase opposite to that of the class B power amplifier 51a, but the class B power amplifier 51b is connected to the voice coil 52b in a phase opposite to that of the class B power amplifier 51a and functions as a phase inverting means. In one positive cycle of the input signal D, the direction of the current flowing through the voice coil 52a is from the + terminal to the-terminal of the voice coil 52b. This is in the same direction as the direction of the current flowing to the voice coil 52a in this half cycle. In the negative half cycle of the input signal D, the direction of the current flowing through the voice coil 52a is also the same. Therefore, the driving forces of the speaker cones generated in the two voice coils with respect to the input signal D are in the same direction, and the speaker 52 is driven by the same output as in the conventional example.

Considering the time immediately after the power is turned on, the class B power amplifiers 51a and 51b transiently flow a transient current from their + output terminals as shown in the conventional example. This transient current is the voice coil 52a. Flows from the + terminal to the − terminal, and to the voice coil 52b from the − terminal to the + terminal. Therefore, the speaker cone driving forces generated in the respective voice coils due to the transient current have opposite directions, so that they cancel each other out and the speaker does not generate shock noise due to the transient current.
Even immediately after the power is turned off, the class B power amplifier 5
1a and 51b draw the transient current from the + output terminal, but the speaker cone driving force does not occur because the direction of the current flowing through the voice coils 52a and 52b is opposite to that at the time of turning on, so that the shock noise due to the transient current is generated. Does not occur. Further, although the transient current has been described here, it goes without saying that shock noise is not generated by canceling out noise generated in other class B power amplifiers in the same manner.

Although the case where the number of class B power amplifiers is two has been described here, it is needless to say that when there are three or more class B power amplifiers, the phase inverting means is provided in half of the class B power amplifiers to perform the same operation. Nor.

Example 5. FIG. 11 is a configuration diagram showing the fifth embodiment. In this figure, the input to the subtraction calculation means 14 is opposite to that in the first embodiment, and the signal v1 output from the input terminal B is input to the input terminal 100, and the input terminal 1
The signal v2 output from the gain limiting means 13 is input to 01. The output of the class B power amplifier 11b is connected to the voice coil 12b in antiphase.

Next, the operation will be described. Input terminal 10 of subtraction calculation means 14 in the preceding stage of class B power amplifier 11b
0 and the input terminal 101 are interchanged and wired, so when the gain limiting means 13 is operating (signal v
2 voltage-voltage of signal v1) signal v4 is output. By the way, ((voltage of signal v2−voltage of signal v1)
= − (Voltage of the signal v1−voltage of the signal v2)), while the subtraction calculation means 14 outputs the signal (voltage of the signal v1−voltage of the signal v2) in the first embodiment, the signal v4 Becomes the opposite phase of the signal v3. However, since the connection between the class B power amplifier 11b and the voice coil 12b is in the opposite phase, a current having the same phase as the signal v1 flows in the voice coils 12a and 12b, and the speakers are normally driven in parallel. At this time, class B power amplifier 11
Since the transient current flowing when the power source of b is turned on and off has a reverse phase to the transient current flowing in the class B power amplifier 11a and flows into the voice coil 12b, the two voice coils cancel each other in the opposite direction. The effect is that shock noise is not generated when the power is turned on and off.

Example 6. FIG. 12 is a sixth embodiment according to the present invention.
The configuration of is explained. In the sixth embodiment, the input terminal 100 of the gain limiting means 13 and the subtraction calculating means 14 of the first embodiment is used.
The low-pass attenuation means 61 such as a general low-frequency pass filter is inserted between and.

Next, the operation will be described. Low frequency attenuation means 6
1 attenuates the low range of the signal v2 and outputs the signal v5.
Since the signal v5 is input to the input terminal 100 of the subtraction calculation means 14 and the signal v1 whose low frequency band is not attenuated is input to the other input terminal 101, the signal output from the subtraction calculation means 14 v6 includes the low frequency signal attenuated by the low frequency attenuation means 61. Therefore, the class B power amplifier 11b amplifies the signal v6 including the low frequency band, while
Since the class power amplifier 11a amplifies the normal signal v2, the low frequency band increases from the output of the speaker. This works regardless of whether the signal passing through reaches the output level at which the gain limiting means 13 operates. Other configurations and operations are the same as those in the first embodiment, and thus the description thereof will be omitted.

As described above, in the sixth embodiment, while the effect of increasing the driving efficiency of the amplifier of the first embodiment is obtained, the bass signal is enhanced by using the low-pass attenuating means such as the low-pass filter, especially in the vehicle interior. It is intended to improve the bass feeling that tends to be insufficient.

Example 7. FIG. 13 is a configuration diagram showing a seventh embodiment according to the present invention. The seventh embodiment is a gain limiting means 1
3 and the input terminal 100 of the subtraction calculation means 14, a high-frequency attenuation means 71a using a general high-pass filter or the like is inserted between the input terminal B and the input terminal 101 of the subtraction calculation means 14. A high-frequency attenuation means 71b having the same characteristics as the high-frequency attenuation means 71a is inserted in the.

Next, the operation will be described. Depending on the characteristics of the gain limiting means 13, the phase of the output of the gain limiting means 13 may change when the output is in a high frequency range, resulting in a deviation from the input signal of the gain limiting means 13 and subtraction. The calculation unit 14 outputs the difference signal to drive the class B power amplifier 11b, which increases the internal loss and reduces the efficiency of the device. In order to prevent this, in order to input only the signal in the frequency band in which the phase characteristic of the gain limiting means 13 does not change to the subtraction calculating means 14, the high frequency attenuating means 71a attenuates the high frequency area, and the input is performed. A high-frequency attenuation means 71b is provided in order to keep the high frequency components of the input to the terminal 100 and the input to the input terminal 101 the same. The other configurations and operations are the same as those in the first embodiment, and the description thereof will be omitted.

Although the class B power amplifier is used in each of the above embodiments, a BTL amplifier in which two class B power amplifiers are paired and balance-connected may be used.

Further, in each of the above embodiments, the power amplifiers do not necessarily have to have the same output, and B having several different outputs matching the total output to be driven.
It can be configured with a combination of class power amplifiers.

Needless to say, not only the class B power amplifier but also a class AB power amplifier or the like may be used.

[0057]

In the speaker device according to the present invention, the noise generated in one amplifying means cancels out the noise generated in the other amplifying means, so that the noise generated in the amplifying means is reduced. You can

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a gain limiting unit according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing a subtraction calculation means according to the first embodiment of the present invention.

4 shows Embodiment 1 of the present invention, FIG. 4a is a diagram showing the relationship between the voltage at one input of the subtraction calculation means and the voltage at the input terminal B, and FIG. 4b is the subtraction calculation means. A diagram showing the relationship between the voltage of the other input of the above and the voltage of the signal input terminal B,
FIG. 4c is a diagram showing the relationship between the voltage of the output of the subtraction calculation means and the voltage of the signal input terminal B.

FIG. 5 is a diagram showing the relationship between the internal loss and the output of two class B power amplifiers according to the first embodiment of the present invention.

FIG. 6 is a configuration diagram showing a second embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between internal loss and output of four class B power amplifiers according to the second embodiment of the present invention.

FIG. 8 is a configuration diagram showing a third embodiment of the present invention.

FIG. 9 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 10 is a configuration diagram showing a phase inverting means in embodiment 4 of the present invention.

FIG. 11 is a configuration diagram showing a fifth embodiment of the present invention.

FIG. 12 is a configuration diagram showing a sixth embodiment of the present invention.

FIG. 13 is a configuration diagram showing a seventh embodiment of the present invention.

FIG. 14 is a configuration diagram showing a first conventional multi-voice coil speaker system.

FIG. 15 is a graph showing the relationship between the output level and the internal loss of the class B power amplifier in the first conventional multi-voice coil speaker system.

FIG. 16 is a configuration diagram showing a class B power amplifier in a first conventional multi-voice coil speaker system.

FIG. 17 is a waveform diagram showing a transient current in the first conventional multi-voice coil speaker system.

FIG. 18 is a configuration diagram showing a second conventional multi-voice coil speaker system.

FIG. 19 is a diagram showing a relationship between internal loss and output of a class B power amplifier in a second conventional multi-voice coil speaker system.

[Explanation of symbols]

1a ... Class B power amplifier, 1b ... Class B power amplifier, 2
… Multi-voice coil speaker, 2a… Voice coil,
2b ... Voice coil, 3 ... Speaker cone, 5a ... Class B power amplifier, 5b ... Class B power amplifier, 5c ... Class B power amplifier, 5d ... Class B power amplifier, 6a ... Voice coil, 6b ... Voice coil, 6c ... Voice coil, 6d
... voice coil, 7 ... speaker cone, 11a ... class B power amplifier, 11b ... class B power amplifier, 12 ... multi-voice coil speaker, 12a ... voice coil, 12b
... voice coil, 12c ... speaker cone, 13 ... gain limiting means, 14 ... subtraction calculation means, 16a ... voice coil, 16b ... voice coil, 16c ... voice coil, 1
6d ... Voice coil, 17a ... Class B power amplifier, 17
b ... Class B power amplifier, 17c ... Class B power amplifier, 1
7d ... Class B power amplifier, 18a ... Gain limiting means, 18
b ... Gain limiting means, 18c ... Gain limiting means, 19 ... Subtraction arithmetic means, 20 ... Subtraction arithmetic means, 21 ... Subtraction arithmetic means,
20a ... 1st motor, 20b ... 2nd motor, 20c
... third motor, 21a ... first transistor, 21b
... second transistor, 21c ... third transistor,
23a ... 1st gain limiting means, 23b ... 2nd gain limiting means, 24a ... 1st subtraction calculating means, 24b ... 2nd subtraction calculating means, 28 ... Load, 51a ... Class B power amplifier,
51b ... Class B power amplifier, 52 ... Multi-voice coil speaker, 52a ... Voice coil, 52b ... Voice coil, 53 ... Phase inversion means, 61 ... Low-frequency attenuation means, 71a
... high-frequency attenuation means 71b ... high-frequency attenuation means.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI // H02P 7/68 H02P 7/68 D 7/69 7/69 (58) Fields investigated (Int.Cl. ⁷ , DB name) ) H03F 3/26 H03F 3/68 H04R 3/14 H02P 7/68 H02P 7/69 H04R 3/00 310 H03F 1/00

Claims (3)

(57) [Claims] 1. A pair of amplifying means having the same characteristics for amplifying one input signal, one speaker driven by the pair of amplifying means, and a preceding stage of one of the pair of amplifying means. A speaker device comprising a phase inverting means provided at a subsequent stage. 2. A first input signal for receiving and amplifying the input signal
Amplification means, a first voice coil connected to the first amplification means to drive a speaker cone, and a second amplification having the same characteristics as the first amplification means for amplifying the input signal by inputting the input signal through the phase inversion means. Means and a second voice coil connected to the second amplifying means to drive the speaker cone, wherein the polarity of the wiring between the first amplifier and the first voice coil connected to the first amplifier is the second amplifier. And a speaker device connected in a phase opposite to the polarity of the wiring with the second voice coil connected thereto. 3. A first input signal for receiving and amplifying the input signal
Amplification means, a first voice coil connected to the first amplification means to drive a speaker cone, and a second amplification having the same characteristics as the first amplification means for amplifying the input signal by inputting the input signal through the phase inversion means. Means and a second voice coil connected to the second amplifying means to drive the speaker cone, wherein the polarity of the wiring between the first amplifier and the first voice coil connected to the first amplifier is the second amplifier. And the second voice coil connected to the second voice coil are connected in reverse phase with respect to the polarity of the wiring,
A speaker device in which driving forces of speaker cones generated in one voice coil are in the same direction.