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JP2001285985

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DESCRIPTION JP2001285985
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker apparatus in which a plurality of amplifier means such as class B power amplifiers and
driving means such as voice coils are configured to drive loads such as speakers in parallel. .
[0002]
2. Description of the Related Art In general, in a multi voice coil speaker system in which one
speaker cone is vibrated by a plurality of voice coils, a voice coil to which a bass of L signal of
stereo signal is input and a voice coil to which a bass of R signal is input Is used as a so-called 3D
central speaker that drives one speaker cone by two voice coils, or a voice coil is connected to
each of a plurality of amplifiers to drive one speaker cone, an amplifier Used to increase the
overall maximum power.
[0003]
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.
Assuming that the power supply voltage is Vcc and the impedance of the voice coil is RL, the
maximum output value P0 (MAX) of the class B power amplifier, which is a commonly used
speaker drive power amplifier, is P0 (MAX) = Vcc2 / 8RL Equation (1) is obtained. Therefore, in
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order to increase the value of P0 (MAX), it is necessary to either increase the power supply
voltage Vcc or lower the impedance RL of the voice coil. However, it is difficult to raise the
battery power supply voltage to raise VCC in automotive audio equipment and the like, and it is
not easy to lower RL because of limitations in manufacturing voice coils or wiring impedance.
Therefore, a multi-voice coil speaker system using a plurality of class B power amplifiers in
parallel is used.
[0004]
FIG. 14 is a configuration 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 a single speaker cone 3 (described later) with two
voice coils 2a and 2b. It is a multi voice coil speaker to be vibrated. An input signal A is input in
parallel to the B-class power amplifiers 1a and 1b, and the output of each is input to voice coils
2a and 2b. A speaker cone 3 functions as a diaphragm driven by the voice coils 2a and 2b.
[0005]
Next, the relationship between the output of the class B power amplifier and the internal loss will
be described. Here, assuming that the output of the class B power amplifier is P0 and the internal
loss is PC, it is known that the relation is PC = (Vcc / 2) × (P0 / RL) 1 / 2−P0 (2) It is done.
Therefore, if one B-class power amplifier is used, and if the B-class power amplifier drives the
speaker with the output P0A, then assuming that the internal loss at this time is PCA, from
equation (2), PCA = (Vcc / 2) * (P0A / RL) 1/2-P0A (3) It becomes Formula. On the other hand,
when two B-class power amplifiers are used, each B-class power amplifier needs to handle half
the output POA in order to obtain the output P0A with these two B-class power amplifiers. The
internal loss PCB of the class B power amplifier is PCB = (Vcc / 2) * {(P0A / 2) / RL} 1 / 2- (P0A /
2) (4) from the equation (2). Therefore, the total value 2PCB of internal losses of two class B
power amplifiers is: 2PCB = 2 × [(Vcc / 2) × {(P0A / 2) / RL} 1 / 2− (P0A / 2) = (Vcc /) 2) ×
21/2 × (P0A / RL) 1 / 2−P0A (When the same output P0A is to be output by comparing the
equations (5) and (3), the class B power amplifier It can be seen that the internal loss of the class
B power amplifier in the two speaker systems is higher than that in the one speaker system.
Further, FIG. 15 is a characteristic diagram of the class B power amplifier in which the horizontal
axis represents the output value and the vertical axis represents the internal loss, and curve A in
FIG. 15 represents the output of one class B power amplifier and the internal loss. The
relationship is shown, and curve i shows the relationship between the total output of the two
class B power amplifiers and the total internal loss. It can also be seen from this figure that the
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internal loss of the speaker system with two B-class power amplifiers is larger than that with one
speaker system.
[0006]
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 1 d and is input to the base of the transistor 1
e of the first stage. This input signal is amplified by the transistor 1e, taken out of the collector
load resistor 1f of the transistor 1e, and applied to the base of the transistor 1g of the next stage.
The input signal is further amplified, taken out from the collector load resistor 1h of the
transistor 1g, and input to the push-pull driver circuit constituted by the final stage transistors 1i
and 1j. The diodes 1k and 1L are for providing a 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 supply
Vcc by the voltage Vcc / 2, the voltage Vcc / 2 is applied across the output capacitor 1c.
[0007]
Assuming that 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 is turned on to push a current from the +
terminal of the output capacitor 1c toward the-terminal to make the voice coil 2a hot. The
speaker drive current flows from the side (indicated by + in the figure) to the earth side
(indicated by-in the figure). On the other hand, when the bases of the transistors 1i and 1j are
swung in the negative direction, the transistor 1j is turned on to draw current from the negative
terminal of the output capacitor 1c to the positive terminal, and the voice coil 2a is hot from the
ground side Loudspeaker drive current flows.
[0008]
As described above, in order to prevent the output capacitor 1c from flowing a direct current to
the voice coil 2a in the class B power amplifier 1a and to allow a current in the positive /
negative direction to flow in the voice coil 2a. It is provided.
[0009]
FIG. 17 is an explanatory view showing a transient current flowing in the class B power amplifier.
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Here, considering the transition state when the power supply voltage Vcc in the class B power
amplifier 1a is on and off, when the power supply Vcc is supplied to the class B power amplifier
1a, charging is performed as shown in FIG. Such a transient current flows to the voice coil 2a. On
the other hand, when the power supply Vcc of the B-class power amplifier 1a is turned off, a
transient current as shown in FIG. 17 (b) flows to the voice coil 2a in the reverse direction due to
the discharge of the capacitor 1c. As described above, when the power supply of the class B
power amplifier is turned on and off, a transient current flows through the voice coil 2a, and this
transient current is input to the speaker and a shock noise causing the user's discomfort is
generated from the speaker.
[0010]
FIG. 18 is a block diagram showing a second conventional multi-voice coil speaker system, and
FIG. 19 is a relationship diagram showing the relationship between internal loss and output
among a plurality of class B power amplifiers. In FIG. 19, the curve a shows the characteristics
per class B power amplifier, and the curve i shows the characteristics as a whole for the class B
power amplifier. In these figures, 5a, 5b, 5c and 5d are class B power amplifiers having
characteristics similar to those of class B power amplifiers 1a and 1b in the first conventional
multi voice coil speaker system, and this class B power amplifier 5a , 5b, 5c, 5d respectively
amplify the input signal and output it to the voice coils 6a, 6b, 6c, 6d to drive one speaker cone
7. In the multi-voice coil speaker system configured as described above, the characteristics of the
entire class B power amplifier are as shown by curve A in FIG. 19, so as can be seen by
comparing this curve a and curve i, In the above-described conventional multi-voice coil speaker
system as well as the first conventional multi-voice coil speaker system, the internal loss is
increased and the efficiency of driving the speaker is reduced.
[0011]
Since the first conventional multi-voice coil speaker system or the second conventional multivoice coil speaker system is configured as described above, it is driven by one B-class power
amplifier. Although the power for driving the speaker can be increased more than in the case, the
internal loss is increased, so that the efficiency for driving the speaker is reduced or the amount
of heat generation is increased.
[0012]
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In addition, when the power of the class B power amplifier is turned on and off, a transient
current transiently flows in the voice coil, and this is generated as a shock noise from the
speaker.
[0013]
The present invention has been made to solve such problems, and it is an object of the present
invention to provide a speaker device that does not generate shock noise.
[0014]
A speaker apparatus according to the present invention comprises a pair of amplifying means for
amplifying one input signal, a speaker driven by the pair of amplifying means, and the pair of
amplifying means. It is equipped with the phase inversion means provided in the front | former
stage of the one amplification means among the amplification means, and the back | latter stage.
[0015]
Further, a first amplification means for inputting an input signal and amplifying it, a first voice
coil connected to the first amplification means for driving a speaker cone, the input signal is
inputted via a phase inverting means, and is amplified A second amplification means having the
same characteristics as the first amplification means, and a second voice coil connected to the
second amplification means for driving the speaker cone, the first amplifier and the first
connected to the first amplification means The polarity of the wiring with the voice coil is
connected in the opposite phase to the polarity of the wiring between the second amplifier and
the second voice coil connected thereto.
[0016]
Further, a first amplification means for inputting an input signal and amplifying it, a first voice
coil connected to the first amplification means for driving a speaker cone, the input signal is
inputted via a phase inverting means, and is amplified A second amplification means having the
same characteristics as the first amplification means, and a second voice coil connected to the
second amplification means for driving the speaker cone, the first amplifier and the first
connected to the first amplification means The polarity of the wiring with the voice coil is
connected in reverse phase to the polarity of the wiring between the second amplifier and the
second voice coil connected thereto, and the two voices are connected to the input signal. The
driving forces of the speaker cones respectively generated in the coils are in the same direction.
[0017]
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In the speaker device according to the present invention, the noise generated from the inside of
one of the amplification means cancels out the noise generated from the inside of the other
amplification means.
[0018]
EXAMPLES The following is a summary of the examples.
The speaker apparatus according to this embodiment comprises: signal level limiting means for
limiting an input signal to a predetermined signal level or less and outputting the same;
subtraction operation means for outputting a difference between the input signal and the output
of the signal level limiting means; It is driven by the first amplification means for amplifying the
output of the level limiting means, the second amplification means for amplifying the output of
the subtraction operation means, and the output of the first amplification means and the output
of the second amplification means One speaker is provided.
[0019]
With this configuration, the input signal below the predetermined signal level is amplified by the
first amplification means, and the difference between the input signal and the input signal below
the predetermined level is amplified by the second amplification means, the first One speaker is
driven by an output obtained by combining the output of the amplification means and the output
of the second amplification means, thereby reducing the internal loss in the first amplification
means and the second amplification means, and driving the speakers Efficiency can be improved.
[0020]
In addition, 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 operation means for outputting the
difference between the signal levels before and after this signal level limiting means. A signal
level area dividing means for dividing an input signal into a plurality of signal level areas, a
plurality of amplifying means for amplifying the plurality of signal level areas, and a speaker
driven by the outputs of the plurality of amplifying means are provided. It is
[0021]
According to this configuration, one input signal is divided into a plurality of signal level areas by
the signal level area dividing means and amplified respectively to drive one speaker. The loss can
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be reduced, and the efficiency of driving one speaker can be improved.
[0022]
In addition, a pair of amplification means for amplifying one input signal, one speaker driven by
the pair of amplification means, and one stage before and one stage of one of the pair of
amplification means are provided. And the phase inverting means.
With this configuration, the noise generated from the inside of one amplification means cancels
out the noise generated from the inside of the other amplification means, so the noise generated
in the amplification means can be reduced.
[0023]
Also, low-pass attenuation means is provided between the signal level limiting means and the
subtraction operation means.
With such a configuration, the signal of which the low range has been attenuated is input from
the signal level limiting means to the subtraction means, so that the output of the subtraction
means increases the low range, especially the low range. The low frequency can be compensated
when used in the place where the noise is generated.
[0024]
Further, a first high-frequency attenuation means for attenuating high frequencies above a
predetermined value of the input signal is provided in the front stage of the subtraction
operation means, and provided between the subtraction operation means and the signal level
limiting means A second high band attenuation means having the same frequency characteristic
as the high band attenuation means is provided between the subtraction operation means and
the signal level limiting means.
With this configuration, the noise of the high frequency component above the predetermined
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value generated from the inside of the signal level limiting means is not output from the
subtraction operation means.
Therefore, the second amplification means does not operate with the high frequency component
equal to or more than the predetermined value, so that the internal loss can be reduced and the
efficiency of driving the speaker can be improved.
[0025]
The amplifying apparatus according to this embodiment comprises: signal level limiting means
for limiting the signal level of one input signal; subtraction operation means for outputting a
difference between the input signal and the output of the signal level limiting means; and signal
level limiting means A first amplification means for amplifying the output of the second
amplification means for amplifying the output of the subtraction operation means, an output of
the first amplification means, and an output of the second amplification means And output signal
output means for outputting.
With this configuration, the input signal below the restricted signal level is amplified by the first
amplification means, and the difference between the input signal and the input signal below the
restricted signal level is amplified by the second amplification means An output obtained by
combining the output of the first amplification means and the output of the second amplification
means is output as one output signal.
Therefore, the internal loss in the first amplification means and the second amplification means
can be reduced, and the efficiency can be improved.
[0026]
The load driving device according to this embodiment performs subtraction operation for
outputting a difference between a signal level limiting means for limiting and outputting one
input signal to a predetermined signal level or less and an output of the one input signal and the
signal level limiting means. Means and an output of the signal level limiting means, the ratio of
the increase in internal loss to the increase in driving force when the signal level of the output of
the signal level limiting means is a predetermined signal level (increasing of internal loss /
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driving force By a first drive unit having a characteristic in which the increase) decreases with an
increase in drive force, a second drive unit operated by the output of the subtraction operation
unit, and a first drive unit and a second drive unit One load to be driven is provided.
With such a configuration, the first drive unit to which an input signal at a predetermined signal
level or less is input and the second drive unit to which a difference between the input signal and
an input signal at a predetermined signal level or less is input It drives one load.
Therefore, the internal loss in the first drive means and the second drive means can be reduced,
and the efficiency of driving the load can be improved.
[0027]
Example 1
FIG. 1 is a block diagram showing Embodiment 1 of the present invention, and FIG. 2 is a block
diagram showing gain limiting means. 11a and 11b are class B power amplifiers having the same
characteristics. 12 is a multi-voice coil speaker having two voice coils 12a and 12b and one
speaker cone 12c vibrated by the two voice coils 12a and 12b, and 13 has its output less than a
fixed voltage by limiting its gain. Gain limiting means for limiting and outputting, has two input
terminals 100 and 101 and has 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 The subtraction operation means outputs a signal from the output terminal 102.
[0028]
Here, the signal v1 is inputted to the gain limiting means 13 from the input terminal B, and the
gain limited signal v2 is outputted to the input terminal 100 of the subtraction operation means
14 and the class B power amplifier 11a. The subtraction operation means 14 receives the signal
v2 at the input terminal 100, receives the signal v1 at the input terminal 101, and outputs the
signal v3 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.
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[0029]
FIG. 2 is a block diagram showing the gain limiting means 13 in FIG. In this figure, the signal v1
is input to the input, passes through the VCA (voltage control gain variable amplifier) 13a, and is
output as the signal v2. The gain of this VCA 13a is controlled as follows. The level of the output
of the VCA 13a is detected by the envelope detector 13b and the rectifier 13c, and the level
detected by this level is compared with the reference level output from the reference level output
unit 13d by the comparator 13e. If it is larger than the reference level output unit 13d, the
control voltage generation unit 13f generates a control voltage so as to decrease the gain of the
VCA 13a, and feedback controls the VCA 13a so that the output of the reference level output unit
13d 整流 the rectifier 13c output. As a result, the output of the gain limiting circuit 13 becomes
settled below the reference level, and a so-called "limiter" operation is performed in which the
signal v2 does not become an output above the reference level.
[0030]
FIG. 3 is a block diagram showing the subtraction operation means 14 in FIG. The reference
numeral 14a denotes an operational amplifier, and the reference numeral 14b denotes a resistor
of resistance R, which are connected as shown in FIG. 3 to constitute a differential amplifier
circuit. Therefore, the subtraction operation means 14 subtracts the voltage value of the signal
v2 from the voltage value of the signal v1 from the signal v2 inputted to the input terminal 100
and the signal v1 inputted to the input terminal 101 (v1-v2) It outputs a signal v3 having a
voltage value.
[0031]
Next, the operation will be described. FIG. 4 is a diagram showing the relationship between the
input / output voltage of the subtraction operation means 14 and the voltage value of the signal
v1. FIG. 4 (a) is the relationship between the voltage value at the input terminal 101 and the
voltage value of the signal v1. 4 (b) shows the relationship between the voltage value of signal v2
and the voltage value of signal v1. FIG. 4 (c) shows the relationship between the voltage value of
signal v3 and the voltage value of signal v1. FIG. Here, the signal v 1 is inputted to the gain
limiting means 13 and also to the input terminal 101 of the subtraction operation means 14.
Therefore, as shown in FIG. 4A, the voltage value of the signal v1 becomes the voltage value at
the input terminal 101 as it is. On the other hand, since the signal v2 input to the input terminal
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100 of the subtraction operation means 14 is the output of the gain limiting means 13 which
does not output a signal of a predetermined level or more, the signals v2 and v1 are as shown in
FIG. The relationship is as shown. Accordingly, the relationship between the signal v3 of the
subtraction operation means 14 and the signal v1 is that the subtraction operation means 14
outputs the voltage of the difference between the voltage value of the signal v1 and the voltage
value of the signal v2 as shown in FIG. 4 (b) from FIG. 4 (b), resulting in the relationship as
shown in FIG. 4 (c).
[0032]
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. That is, when the
signal v1 increases, at first, only the B class power amplifier 11a operates first, and the class B
power amplifier 11a starts when the signal v1 reaches a certain value. Holds the output and
operates so that the class B power amplifier 11b outputs the signal based on the signal v3
corresponding to the increment of the signal v1 for the first time. Here, as shown in FIG. 4, since
the sum of the signal v2 and the signal v3 is the signal v1, the speaker cone 12c is driven as in
the case of being driven by amplifying the signal v1. Become.
[0033]
FIG. 5 is a diagram showing the relationship between the output of the class B power amplifier
and the internal loss. Here, how the internal loss with respect to the output is obtained in the first
embodiment will be described. In the first embodiment, the signal level to which output limitation
is applied by the gain limiting means 13 is set to a value immediately before the output of the
class B power amplifier 11a starts to be distorted. The relationship between output power and
internal loss at this time is shown in FIG. 5 is the “point a” shown in FIG. Generally, this point
is a region where the internal loss decreases inversely with the increase of the output as shown
in FIG. 5, so the ratio of (internal loss / output) is small and the driving efficiency is good. It can
be said that it is the point.
[0034]
As described above, in the present embodiment, only the B class power amplifier 11a operates
first and the B class power amplifier 11b outputs the subsequent increment after the B level
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power amplifier 11a operates and the output reaches a predetermined level. Therefore, the
overall output vs. total internal loss characteristic of the class B power amplifiers 11a and 11b is
the output vs internal loss of the class B power amplifier 11b at the point “a” in FIG. 5 where
the drive efficiency of the class B power amplifier 11a is high. The characteristics are connected
to each other, and the characteristics shown by the curve c in FIG. 5 are obtained. Here, the curve
i 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 i, the driving method according to the present embodiment is a method
having a high driving efficiency with a small internal loss apparently compared to the first
conventional example. I understand that. Further, it goes without saying that if the internal loss is
small, the heat generated from the class B power amplifier is also reduced.
[0035]
Example 2 FIG. 6 is a block diagram showing a multi voice coil speaker system according to a
second embodiment in which four B class power amplifiers drive a multi voice coil speaker
having four voice coils. 16 is a multi voice coil speaker, 16a, 16b, 16c and 16d are first, second,
third and fourth voice coils respectively, and 17a, 17b, 17c and 17d are class B driving them. It is
a power amplifier. Gain limiting means 18a, 18b and 18c similar to the gain limiting means in the
first embodiment are provided at the front stage of each class B power amplifier, and further, the
same as in the first embodiment are provided at the front stage of the gain limiting means 18b
and 18c. The 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 connected to the
front stage of the class B power amplifier 17 d. The subtraction operation means 19, 20, 21
receives at its two input terminals the signals input to the gain limiting means 18a, 18b, 18c and
the signals output from the gain limiting means 18a, 18b, 18c, respectively. A signal having a
voltage (voltage of input signal-voltage of output signal) of the gain limiting means 18a, 18b, 18c
is output.
[0036]
Next, the operation will be described. First, when the input signal C is input, the input signal C
passes through the gain limiting means 18a and drives the class B power amplifier 17a. Here,
since the gain limiting means 18a is the same as that of the first embodiment, when the signal
input is small, the input and the output are the same signal. Therefore, since the subtraction
operation 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
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increases and the gain limiting means 18a operates, the class B power amplifier 17b outputs an
output equal to or greater than the predetermined value of the input as in the first embodiment.
Here, when the input signal further increases, the gain limiting means 18b starts operation, and
the class B power amplifier 17c is similarly driven. The same operation is performed for the class
B power amplifier 17 d hereinafter.
[0037]
FIG. 7 is a diagram showing the relationship between the output and the internal loss in a class B
power amplifier. As shown in FIG. 7, the four class B power amplifiers 17a, 17b, 17c and 17d
start to operate in order as the signal input increases. Therefore, in the same way as in the first
embodiment in which two amplifiers are provided, the relationship between the total output of
these four B class power amplifiers and the total internal loss is the output of one B class power
amplifier to internal The loss curve has the relationship shown in curve a of FIG. 7 connected at
the output point at which each gain limiting means operates. Curve i in FIG. 7 is a curve of total
output versus internal loss when four amplifiers are driven in parallel. From the comparison
between curve a and curve b in FIG. 7, it can be confirmed that the configuration according to
this embodiment is an efficient driving method with less internal loss.
[0038]
Further, although the configuration operation in the case where the number of voice coils is four
has been described in the second embodiment, the same configuration is not limited to only four,
and the multi voice coil speaker system having a plurality of voice coils is also possible. Of
course, the same effect can be obtained.
[0039]
Further, in the gain limiting means in each of the above embodiments, the gain is limited
according to the frequency characteristic by changing the reference level output from the
reference level output unit according to the frequency of the input signal. It is also possible to
eliminate the unnaturalness.
[0040]
Example 3
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13
Furthermore, 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 apparatus for driving one load with a plurality of motors as shown in the third
embodiment. It is possible.
FIG. 8 is an explanatory view showing Embodiment 3 of the present invention. Reference
numerals 20a to 20c denote driving motors having a region in which the ratio between the
increase in output and the increase in internal loss decreases. Reference numerals 21 a to 21 c
denote transistors, and reference numeral 22 denotes 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 fixed
voltage (voltage at which the input to the motors 20a to 20c becomes a region where the ratio
between the increase in output and the increase in internal loss decreases) The gain limiting
means 23a and 23b have the same configuration as the gain limiting means 13 in the first
embodiment. Reference numerals 24a and 24b denote subtraction operation means for
outputting the difference between the two inputs. The subtraction operation means 24a and 24b
have the same configuration as the subtraction operation means 14 in the first embodiment.
Reference numeral 25 denotes a motor control voltage input to which a motor control voltage is
input from the outside. Reference numerals 26a to 26c denote belt pulleys for transmitting the
rotational force of the motors 20a to 20c to the belt 27, and the load 28 is driven by the belt 27.
[0041]
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 predetermined voltage
or less by the first gain limiting means 23a, and is input to the base of the first transistor 21a.
The motor control voltage and the output of the first gain limiting means 23a are input to the
first subtraction operation means 24a. The first subtraction operation means 24a outputs a value
obtained by subtracting the output of the first gain limiting means 23a from the motor control
voltage. The second gain limiter 23b limits the output of the first subtraction operator 24b to a
constant voltage or less as in the first gain limiter 23a, and outputs it to the base of the second
transistor 21b. The output of the first subtraction operation means 24a and the output of the
second gain limiting means 23b are input to the second subtraction operation means 24b, and
the difference between these inputs is the base of the third transistor 21c. Output to 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 bases. By this output, the motors 20a to 20c rotate the belt pulleys 26a
to 26c and drive the load 28 through the belt 27. In the third embodiment configured in this
manner, it is possible to drive the load 28 by reducing the internal loss by the plurality of motors.
09-05-2019
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[0042]
Moreover, although the motor was used in the said Example 3, it should just generate driving
force, such as an engine of an internal combustion engine, for example.
[0043]
Example 4
FIG. 9 is a block diagram showing the fourth embodiment, and FIG. 10 is a circuit diagram
showing phase inversion means. Reference numerals 51a and 51b denote B-class power
amplifiers having the same characteristics, 52 denotes a multi-voice coil speaker provided with
two voice coils 52a and 52b, and 53 denotes phase inverting means as shown in FIG. The phase
inversion means 53 is connected to the front stage of the class B power amplifier 51b, and the
input signal D is input to the phase inversion means 53 and the class B power amplifier 51a. On
the other hand, class B power amplifiers 51a and 51b are connected to voice coils 52a and 52b,
respectively, and the polarity of wiring between class B power amplifier 51b and voice coil 52b
connected thereto is class B power amplifier 51a and this Are connected in reverse phase with
respect to the polarity of the wiring with the voice coil 52a connected to. For example, as shown
in FIG. 10, the phase inverting means 53 is constituted by a general operational amplifier circuit
53 or the like. In FIG. 10, 53a is an operational amplifier, 53b is a resistor and one is inserted
between the input terminal of the circuit and the inverting input terminal (indicated by-in the
figure) of the operational amplifier 53a, and the other is an operational amplifier 53a It is
inserted between the inverting input terminal and the output terminal. Since these two resistors
are equal in value, the operational amplifier circuit 53 functions as phase inverting means 53 for
outputting a signal whose amplitude is the same and the phase is reversed.
[0044]
Next, the operation will be described. Now, assuming that the power supply is turned on and the
device is in a sufficiently stable state, the input signal D is inputted to the class B power amplifier
51a in the positive phase, but the phase inversion means 53 to the class B power amplifier 51b.
For the input signal D, the B-class power amplifier 51a and the B-class power amplifier 51b
operate in opposite phases with respect to the input signal D. Therefore, although the output of
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the class B power amplifier 51b is in reverse phase to the class B power amplifier 51a, the class B
power amplifier 51b is connected in reverse phase to the voice coil 52b and has a function as
phase inverting means. In a positive half cycle of one cycle of the input signal D, the direction of
the current flowing through the voice coil 52a is from the + terminal of the voice coil 52b toward
the-terminal. This is the same direction as the direction of the current flowing to the voice coil
52a in this half cycle. Also in the negative half cycle of the input signal D, the direction is the
same as the direction of the current flowing to the voice coil 52a. Therefore, the driving forces of
the speaker cones respectively 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 that of the
conventional example.
[0045]
Here, considering that immediately after the power is turned on, class B power amplifiers 51a
and 51b transiently flow a transient current from their + output terminal as shown in the
conventional example, but this transient current is transmitted to voice coil 52a. The voice coil
52b flows from the-terminal to the + terminal in the direction from the + terminal to the-terminal.
Therefore, since the speaker cone driving force generated in each voice coil due to the transient
current is in the opposite direction, the speakers cancel each other out and the shock noise due
to the transient current is not generated. Also immediately after the power is turned off, the class
B power amplifiers 51a and 51b draw in a transient current from the + output terminal, but the
direction of the current flowing through the voice coils 52a and 52b is reversed as in the on
state. Since no cone driving force is generated, there is no generation of shock noise due to
transient current. Further, although the transient current has been described here, it is needless
to say that the noise generated inside the other class B power amplifier is similarly canceled out
and no shock noise is generated.
[0046]
Further, although two B-class power amplifiers are described here, it is needless to say that the
same operation is performed by providing phase inverting means in half of the B-class power
amplifiers when there are three or more.
[0047]
Example 5
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FIG. 11 is a block diagram showing a fifth embodiment. In this figure, the input to the subtraction
operation means 14 is reverse to that of the first embodiment, and the signal v1 outputted from
the input terminal B is inputted to the input terminal 100, and the gain limiting means is inputted
to the input terminal 101. A signal v2 output from 13 is input. Further, the output of the class B
power amplifier 11b is connected to the voice coil 12b in reverse phase.
[0048]
Next, the operation will be described. Since the input terminal 100 and the input terminal 101 of
the subtraction operation means 14 in the previous stage of the class B power amplifier 11b are
interchanged and wired, when the gain limiting means 13 is operating (voltage of signal v2signal and outputs a signal v4 of a voltage of v1). By the way, ((voltage of signal v2-voltage of
signal v1) =-(voltage of signal v1-voltage of signal v2)), while in the first embodiment, the
subtraction operation means 14 (voltage of signal v1-signal) Since the signal of voltage v2) is
output, the signal v4 has the reverse phase of the signal v3. However, since the connection
between the B-class power amplifier 11b and the voice coil 12b is in reverse phase, a current
having the same phase as the signal v1 flows through the voice coils 12a and 12b, and the
speakers are normally driven in parallel. At this time, the transient current flowing at the time of
power on / off of the class B power amplifier 11b is in reverse phase to the transient current
flowing to the class B power amplifier 11a and flows to the voice coil 12b, so the two voice coils
cancel each other in opposite directions. Therefore, as in the fourth embodiment, an effect that
shock noise is not generated when the power is on and off can be obtained.
[0049]
Example 6 FIG. 12 illustrates the configuration of the sixth embodiment according to the present
invention. In the sixth embodiment, a low frequency attenuation means 61 such as a general low
frequency range filter is inserted between the gain limiting means 13 of the first embodiment
and the input terminal 100 of the subtraction operation means 14.
[0050]
Next, the operation will be described. The low band attenuation means 61 attenuates the low
band of the signal v2 and outputs a signal v5. Since the signal v5 is input to the input terminal
09-05-2019
17
100 of the subtraction operation means 14 and the signal v1 whose low band is not attenuated is
input to the other input terminal 101, the signal output from the subtraction operation means 14
v6 will include the low band signal attenuated by the low band attenuation means 61. Therefore,
the class B power amplifier 11b amplifies the signal v6 including the low band, and the class B
power amplifier 11a amplifies the normal signal v2, so that the low 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. The other configurations and
operations are the same as those of the first embodiment, and thus the description thereof is
omitted.
[0051]
As described above, in the sixth embodiment, although the effect of increasing the driving
efficiency of the amplifier of the first embodiment is obtained, the low band attenuation means
such as the low band filter is used to enhance the low band signal, and particularly in the vehicle
interior It is an attempt to improve the feeling of low bass.
[0052]
Example 7
FIG. 13 is a block diagram showing Embodiment 7 according to the present invention. In the
seventh embodiment, a high-frequency attenuation means 71a using a general high-pass filter or
the like is inserted between the gain limiting means 13 and the input terminal 100 of the
subtraction operation means 14, and the input terminal B and the subtraction operation means A
high band attenuation means 71 b having the same characteristic as the high band attenuation
means 71 a is inserted between the fourteen input terminals 101.
[0053]
Next, the operation will be described. Depending on the characteristics of the gain limiting means
13, the phase may be changed when the output of the gain limiting means 13 is in the high
frequency range, and there may be a difference between the input signal of the gain limiting
means 13 and the subtraction. Since the calculating means 14 outputs a difference signal to drive
the class B power amplifier 11b, the internal loss increases and the efficiency of the device is
reduced. In order to prevent this, the high frequency attenuation means 71a attenuates the high
09-05-2019
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frequency band to input only the signal of the frequency band where the phase characteristic of
the gain limiting means 13 does not change to the subtraction operation means 14 In order to
maintain the identity of high frequency components of the input to the terminal 100 and the
input to the input terminal 101, high-frequency attenuation means 71b is provided. The other
configurations and operations are the same as those of the first embodiment, and thus the
description thereof is omitted.
[0054]
Furthermore, although a B-class power amplifier is used in each of the above embodiments, a
BTL amplifier in which two B-class power amplifiers are connected in a balanced manner may be
used.
[0055]
Further, in each of the above embodiments, the power amplifiers need not all have the same
output, but can be configured as a combination of class B power amplifiers having several
different outputs matched to the total output to be driven.
[0056]
Furthermore, it goes without saying that not only a class B power amplifier but also, for example,
a class AB power amplifier may be used.
[0057]
According to the speaker device of the present invention, the noise generated from the inside of
one of the amplification means cancels the noise generated from the inside of the other
amplification means, so that the noise generated in the amplification means is reduced. Can.
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