close

Вход

Забыли?

вход по аккаунту

?

JPH06283949

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH06283949
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
audio signal amplifier, and more particularly to howling of a microphone.
[0002]
2. Description of the Related Art In general, in a broadcast studio, a recording studio, a music
performance hall or the like, a microphone is used to enlarge the sound or extract only a
necessary sound. When using this microphone, an audio signal amplifier as shown in FIG. 13 is
required.
[0003]
This conventional device comprises a microphone 2, a head amplifier 4, a microphone amplifier
6, a power amplifier 8, a speaker 10, a howling cut filter 12, and a changeover switch 14. A
microphone volume 16 is connected to the output of the head amplifier 4 and a master volume
18 is connected to the output of the microphone amplifier 6.
[0004]
08-05-2019
1
In this case, the entire device loop is in a positive feedback state due to the amplification degree
of the device, the distance between the microphone 2 and the speaker 10, and the reflected
sound from the peripheral wall of the reproduction sound field, and a kind of oscillation
phenomenon at a predetermined high frequency. (Howling) may occur. In this case, an offensive
high-pitched "key" is output from the speaker 10. Once this howling occurs, it continues to be
output as it is without taking any action.
[0005]
One of the methods of not outputting howling is to manually turn the switch 14 to S1 and turn
on the fixed howling cut filter 12 to remove howling from the audio signal. However, since this
method does not stop howling occurrence itself, once the howling cut filter 12 is turned on, it is
usually left as it is.
[0006]
However, the above-mentioned audio signal amplifier has the following problems.
[0007]
When howling is stopped by a method such as the volume of the microphone volume 16 and the
volume of the master volume 18 being lowered, the user may forget to return the howling cut
filter 12 to the OFF state and leave it in the ON state.
In this case, the audio signal is always removed in the band of the howling cut filter 12, and there
is a problem that the high frequency characteristic of the microphone 2 is deteriorated.
[0008]
An object of the present invention is to solve the above problems and to improve sound quality
while effectively eliminating howling.
[0009]
An audio signal amplifier according to claim 1 is an audio signal amplifier comprising an audio
08-05-2019
2
input means, an amplifier, a gain adjustment means, and an audio output means, provided at a
predetermined portion of the apparatus. Howling elimination filter means for eliminating howling
generated in the audio signal, wherein the howling elimination filter means for starting the
operation by the start control signal and stopping the operation by the stop control signal; A
howling detection means for outputting a howling detection signal and outputting a start control
signal to a howling removal filter means, a simulation amplifier having substantially the same
frequency characteristics as the amplifier, and an output of the simulation amplifier are
interlocked with the gain adjustment means. Simulation gain adjustment means for adjusting the
gain, Simulation howling detection means for detecting whether or not howling has occurred in a
circuit loop formed by the simulation amplifier and the simulation / gain adjusting means, and
detecting the occurrence of howling, and outputting a simulation howling detection signal, A
means inserted in a circuit loop formed by the simulation amplifier and the simulation / gain
adjustment means, for adjusting the degree of coupling of the circuit loop, receiving the howling
detection signal from the howling detection means, and minimizing the degree of loop coupling A
voice signal amplification apparatus comprising: loop coupling degree adjusting means for
sequentially raising the loop coupling degree upon fixing the loop coupling degree upon
receiving the simulation howling detection signal from the simulation howling detection means,
the simulation signal generation apparatus comprising: Cowling detection means, after detecting
the simulation-howling detection signal when detecting the stop of the howling, is characterized
in, that outputs a stop control signal to the howling removal filter means.
[0010]
According to the sound signal amplifier of the present invention, when howling occurs in the
sound signal, the howling detection means detects the howling and outputs a start control signal.
The howling removal filter means operates in response to the start control signal and the
howling is removed.
[0011]
On the other hand, a circuit formed by the simulation amplifier and the simulation gain
adjustment means and having no howling removal filter means is provided, and the loop coupling
degree of this circuit is detected until the simulation howling detection signal is detected by the
loop coupling degree adjustment means. It raises one by one and generates almost the same
howling as the howling.
08-05-2019
3
[0012]
Thereafter, when the howling is stopped while the howling removal filter means is operating, in
the circuit without the howling removal filter means, the simulation howling detection that the
howling stops substantially the same as the howling with the stopping of the howling is stopped.
A means detects and outputs a stop control signal to disable the howling removal filter means.
[0013]
Therefore, when the howling occurs in the audio signal, it is automatically removed, and when
the howling is stopped while the howling removal filter means is operating, the high frequency
characteristic is degraded by not operating the howling removal filter means. To improve sound
quality.
[0014]
DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows the basic configuration of an
audio signal amplifier 5 according to an embodiment of the present invention.
This device 5 comprises a main circuit 7 and a simulation circuit 9.
[0015]
The main circuit 7 is a circuit comprising an audio input means 20 for inputting an audio signal,
an amplifier 22 for amplifying an audio signal, a gain adjusting means 24 for adjusting the gain
of the amplifier 22, and an audio output means 26 for outputting an audio signal. The following
means are provided.
[0016]
When the howling detection means 30 detects howling generated in the audio signal, it outputs a
howling detection signal to the simulation circuit 9 and outputs a start control signal to the
howling removal filter means 28.
The howling removal filter means 28 is provided between the amplifier 22 and the gain
adjustment means 24 and starts operation by the start control signal to remove howling.
08-05-2019
4
[0017]
On the other hand, the simulation circuit 9 is a circuit that generates howling substantially the
same as the howling generated in the main circuit 7, and includes the following means.
[0018]
The simulation amplifier 32 has substantially the same frequency characteristics as the amplifier
22 of the main circuit 7.
The simulation / gain adjustment means 34 receives the output of the simulation amplifier 32
and adjusts the gain in conjunction with the gain adjustment means 24 of the main circuit 7.
[0019]
The loop coupling degree adjusting means 38 is inserted in the circuit loop formed by the
simulation amplifier 32 and the simulation / gain adjusting means 34 to adjust the degree of
coupling of the circuit loop.
When howling occurs in the main circuit 7, the howling detection signal is received from the
howling detection means 30, and the degree of loop coupling is sequentially increased from the
minimum.
Then, when howling substantially the same as the howling generated in the main circuit 7 occurs,
the simulation howling detection signal is received from the simulation howling detection means
36 and the degree of loop coupling is fixed.
[0020]
The simulation howling detection means 36 outputs a simulation howling detection signal when
it detects the occurrence of howling in the simulation circuit 9.
08-05-2019
5
Thereafter, when the gain of the gain adjusting means 24 of the main circuit 7 is lowered to stop
howling of the main circuit 7, the gain of the simulation gain adjusting means 34 is also lowered
in conjunction with this. When the howling of the simulation circuit 9 is stopped, it is considered
that the howling is stopped also in the main circuit 7 without the howling removal filter means
28. For this reason, the stop of the howling of the simulation circuit 9 is detected, and a stop
control signal is output to the howling removal filter means 28 to stop the operation.
[0021]
FIG. 2 shows a block diagram of the apparatus 5 when each means of FIG. 1 is configured in a
specific hardware. This device 5 comprises a main circuit 7 and a simulation circuit 9.
[0022]
The main circuit 7 includes a microphone 2 as sound input means, a head amplifier 4 as
amplifier, a microphone amplifier 6 and a power amplifier 8, a speaker 10 as sound output
means, a microphone volume 16 as gain adjustment means, a master volume 18 and howling A
howling cut filter 28 which is a removal filter means, a howling detection circuit 30 which is a
howling detection means, and a changeover switch 70 are provided.
[0023]
The simulation circuit 9 includes a simulation amplifier (S), a head amplifier 74, a simulation (S),
a microphone amplifier 76 and a simulation (S) amplifier 78, which are simulation amplifiers, and
an automatic attenuator (automatic attenuator) 38, which is loop coupling degree adjustment
means. And simulation (S) microphone volume 86, simulation (S) master volume 88, and
simulation howling detection circuit 36, which are simulation / gain adjustment means.
The head amplifier 4 and the simulation head amplifier 74, the microphone amplifier 6 and the
simulation microphone amplifier 76, and the power amplifier 8 and the simulation power
amplifier 78 have substantially the same frequency characteristics. Further, the microphone
volume 16 and the simulation microphone volume 86, the master volume 18 and the simulation
master volume 88 are linked together.
08-05-2019
6
[0024]
In this device 5, in the normal case, the terminal of the changeover switch 70 is connected to s1,
so the audio signal input to the microphone 2 is amplified from the speaker 10 through the head
amplifier 4, the microphone amplifier 6, and the power amplifier 8. Is output.
[0025]
Here, it is assumed that the entire loop of the main circuit 7 is in a positive feedback state, and
howling of the microphone 2 occurs.
Once this howling P is generated, its amplitude is successively amplified and continues to
oscillate, so it becomes saturated at power amplifier 8 and is a signal with a high frequency and a
larger amplitude than a normal audio signal. (See FIG. 3a). The device 5 first applies the
generated howling P to the howling detection circuit 30. The howling detection circuit 30
determines whether or not the amplitude of the howling P exceeds the reference amplitude K,
and if it exceeds the reference amplitude K (see FIG. 3 b), a control signal generated based on the
occurrence of the howling P Output C (start control signal). Then, the output of the control signal
C turns on the howling cut filter 28 to remove the howling P (see FIG. 3C).
[0026]
In this embodiment, the control signal C is a signal for turning on the howling cut filter 28 and
turning it off after a predetermined time (see FIG. 8 r). This is because, in the case of sudden
howling, once the howling is removed by the howling cut filter 28, since the howling does not
occur thereafter, the howling cut filter 28 is immediately turned OFF.
[0027]
However, when the howling P remains in spite of how many times the control signal C is output,
it is judged that the howling P continues to occur, and the howling cut filter 28 is kept in the ON
state. This eliminates the subsequent howling.
08-05-2019
7
[0028]
On the other hand, if the howling cut filter 28 is in the ON state, the high frequency
characteristics of the audio signal are degraded. For this reason, it is preferable to prevent
howling from occurring even if the howling cut filter 28 is turned off by, for example, lowering
the volume of the master volume 18. However, if how much volume is lowered, it is not known
whether howling does not occur when the howling cut filter 28 is off.
[0029]
Therefore, in the present apparatus 5, a simulation circuit 9 is provided to confirm the stop of
the howling P when the howling cut filter 28 is off. That is, simulation circuit 9 is substantially
the same circuit as main circuit 7 except that there is no howling cut filter 28, and volumes 16
and 18 of main circuit 7 interlock with volumes 86 and 88 of the simulation circuit. Provided in
Then, howling P 'which is substantially the same as the actual howling P is generated. Thereafter,
when the volume of the master volume 18 is lowered, the simulation master volume 88 of the
simulation circuit 9 is also lowered accordingly, so that the howling P ′ is stopped in the
simulation circuit 9. When the stop of the howling P 'is detected, the control signal C (stop
control signal) is output to the howling cut filter 28.
[0030]
In the main circuit 7, it is determined that the howling P is stopped even if the howling cut filter
28 is turned OFF in response to the stop of the howling P 'being confirmed in the simulation
circuit 9 without the howling cut filter 28. Can. これにより、ハウリングカット・フィルタ28を
OFFにすることができる。
[0031]
Hereinafter, the howling detection circuit 30 outputting the control signal C (start control signal
and stop control signal) will be described, and the simulation circuit 9 outputting the control
signal C (stop control signal) will be described later.
[0032]
08-05-2019
8
The howling detection circuit 30 generates a control signal C based on the howling P.
As shown in FIG. 4, the circuit 30 includes a control signal generation circuit 66 (a start signal
generation circuit 62 and an end signal generation circuit 64) and a signal continuous generation
circuit 68. The start signal generation circuit 62 compares the amplitude of the audio signal with
a predetermined reference amplitude, and generates the start signal of the control signal C when
the amplitude of the audio signal exceeds the predetermined reference amplitude. The end signal
generation circuit 64 generates an end signal of the control signal C which is terminated for a
predetermined time from the start signal.
[0033]
The control signal C is input to the changeover switch 70, and the howling cut filter 28 is turned
on a predetermined time (0.6 seconds in this example) after howling P is generated, and then the
predetermined time (1.8 seconds in this example) I will turn it off later. FIG. 5 shows the start
signal generation circuit 62, and FIG. 6 shows the end signal generation circuit 64. Further, FIG.
7 shows a signal continuous generation circuit 68.
[0034]
Hereinafter, the operation of the apparatus 5 will be described with reference to the time chart of
FIG. First, in the start signal generation circuit 62 of FIG. 5, the start signal of the control signal C
is generated.
[0035]
The voice signal is integrated by the rectifying and integrating circuit 102 and then provided to
the comparator 104. The threshold value of the comparator 104 is set larger than that of the
normal audio signal, and when howling does not occur, the comparator 104 outputs nothing.
Here, when howling P occurs (FIG. 8a), a waveform as shown in FIG. 8b is outputted from the
rectifying and integrating circuit 102. Then, the waveform is shaped by the comparator 104 and
rises about 0.2 seconds after the generation of the howling P (a shown in FIG. 8).
08-05-2019
9
[0036]
Next, this signal is inverted by the inverter 106 and then applied to the integrating circuit 108,
the comparator 110, the inverter 112 and then to the integrating circuit 114, the comparator
116 and the inverter 118, and similarly about 0.2 seconds each in total. .4 seconds later (Figs.
8d, 7e). As a result, a howling P is generated from the toggle flip flop (toggle FF) 120, and rises
about 0.6 seconds later and rises (as indicated by β) signal M is extracted (FIG. 8e). This signal
β is used as the start signal of the control signal C.
[0037]
Next, the end signal generation circuit 64 in FIG. 6 generates an end signal of the control signal
C. The circuit 64 includes a first stage circuit 82 and a second stage circuit 84. First, in the first
stage circuit 82, the output of FIG. 8c is given to the integrating circuit 124 via the inverter 122
and integrated according to a predetermined time constant (FIG. 8f). Then, it is given to the
comparator 126 to obtain the signal R (FIG. 8g). This signal R is applied to the discharge circuit
130 through the integration circuit 128. In the discharge circuit 130, after a predetermined time,
the voltage of the capacitor of the integration circuit 124 is discharged to turn off the signal R
from ON (FIG. 8h). On the other hand, the differentiating circuit 132 creates a signal S for
producing an end signal (which rises 0.2 seconds after howling P is generated) (FIG. 8i). This
signal S and the signal R of the comparator 126 are applied to the OR 134 (FIG. 8j). The output of
OR 134 is applied to toggle FF 136 to produce signal T (FIG. 8k). Then, the inverted signal U (FIG.
8m) of the signal T is given to the reset FF 138. Thereafter, the output of the reset FF 138 (FIG.
8n) and the signal U are applied to the AND 140 to obtain the signal V (FIG. 8o). Next, this signal
V is input to the second stage circuit 84.
[0038]
In the second stage circuit 84, the signal V is applied to the integration circuit 142 and the
comparator 144. This output (FIG. 8p) is applied to the integrating circuit 146, the discharging
circuit 148, and the differentiating circuit 150, similarly to the first stage circuit 82. This output
signal and the signal S of FIG. 8i are applied to the OR 152. Then, the signal W output from the
toggle FF 154 rises at the signal S, and after a predetermined time (2.2 seconds), becomes a
signal (shown by γ) (FIG. 8 q). This signal γ is used as the end signal of the control signal C.
08-05-2019
10
[0039]
The signal W is a reset signal of the toggle FF 120 (see FIG. 5). As a result, the howling P is
generated from the toggle FF 120, and rises about 0.6 seconds later (β in the figure), and then
falls 1.8 seconds (γ in the figure) to output the control signal C (FIG. 8r). As described above, the
control signal C is generated.
[0040]
By this control signal C, the howling cut filter 28 is turned ON 0.6 seconds after the howling P
occurs, and the howling P is removed (PE in the dotted line in FIG. 8A). After 1.8 seconds, the
howling cut filter 28 is turned off.
[0041]
Here, when generation of howling P continues, the signal continuity creating circuit 68 of FIG. 7
is used. The circuit 68 includes toggle FFs 156, 158, 160, 162, an OR 164, and an inverter 166.
The inverted signal QB of the output Q of the toggle FF 120 is applied to the toggle FFs 156, 158,
160, 162 connected in series (four in this example). This output and the output Q of the toggle
FF 120 are applied to the OR 164, and as shown in FIG. 9, a signal in which the control signal C
continues four times is produced. As a result, when the howling P continuously occurs four times,
the howling cut filter 28 is kept in the ON state to remove the subsequent howling.
[0042]
Next, the simulation circuit 9 of FIG. 2 that generates substantially the same howling P 'as the
howling P generated in the main circuit 7 will be described.
[0043]
A circuit diagram of the automatic attenuator 38 is shown in FIG.
08-05-2019
11
The automatic attenuator 38 includes an attenuator unit 92 and a shifter circuit 94. The
attenuator unit 92 includes resistors 202 (2021 to 2027), analog switches 204 (2041 to 2047),
and a resistor 206 which are connected in series. A circuit diagram of the shifter circuit 94 is
shown in FIG. The shifter circuit 94 includes reset FFs 210 and 212 (212 1 to 2126) and 214
(214 1 to 2146), differentiation circuits 216 (216 1 to 2166), comparators 218 (218 1 to 2186),
and inverters 220 (202 1 to 2207) and 224 (2241). .About.2246), AND 226 (2261 to 2266). FIG.
12 shows a time chart of the operation of the automatic attenuator 38. As shown in FIG.
Hereinafter, the operation of the simulation circuit 9 will be described with reference to FIGS.
[0044]
First, when howling P is not generated in the main circuit 7, the shifter circuit 94 of FIG.
Accordingly, in FIG. 10, all of the analog switches 2041 to 2047 are short-circuited, and the
attenuator 92 is grounded, so that the automatic attenuator 38 does not output. That is, the
attenuation degree of the automatic attenuator 38 is maximum (the automatic attenuator output
is minimum).
[0045]
Next, when howling P occurs in the main circuit 7 (FIG. 12a), it is input to the shifter circuit 94 in
FIG. This signal (Q of the toggle FF 120) is first applied to the reset FF 210 (FIG. 12b) and
inverted by the inverter 2201 to output "L" as a shift signal (FIG. 12c). Receiving this, the
terminal of the analog switch 2041 is opened. As a result, the resistor 2021 is connected to the
circuit, and the attenuation of the automatic attenuator 38 is lowered from the maximum by the
distribution of the resistance of the resistor 2021 to the resistance of the resistor 206 (the
output of the automatic attenuator 38 is from 1 to 1). Rank up).
[0046]
This output is applied to the circuit loop of simulation head amplifier 74, simulation microphone
volume 86, simulation microphone amplifier 76, simulation master volume 88, and simulation
amplifier 78.
[0047]
08-05-2019
12
Next, in the shifter circuit 94, a shifter signal is generated.
First, the output of the reset FF 210 is given to the reset FF 2121 through the differentiating
circuit 2161, the comparator 2181, and the inverter 2202 (FIG. 12d to f). This output (FIG. 12g)
is provided to AND 2261. Since howling P has not yet occurred, “H” is output from the
simulation and howling detection circuit 36 (FIG. 12 h) and is given to one of the AND 2261.
These inputs cause the AND 2261 to output a signal "H" (FIG. 12i). Next, the output (FIG. 12 j) is
inverted by the inverter 2241 via the reset FF 2141, and “L” is output as the shifter signal
(FIG. 12 k). The shifter signal is delayed in timing from the shifter signal for a predetermined
time. The attenuator unit 92 receives the “L” of the shifter signal, and the terminal of the
analog switch 2042 is opened. Thereby, the resistor 2022 is connected to the circuit together
with the resistor 2021, and the attenuation of the automatic attenuator 38 is lowered by the
distribution to which the resistance value of the resistor 2022 is further added (the output of the
automatic attenuator 38 is ranked from 1 rank to 2 ranks) Go up to This output is also applied to
the circuit loop.
[0048]
Next, the output of the AND 2261 is given to the AND 2262 via the differentiating circuit 2162,
the comparator 2182, the inverter 2203, and the reset FF 2122. At this time, it is assumed that
howling P ′ occurs in the simulation circuit 9. The generation of the howling P 'is detected by a
simulation and howling detection circuit 36 provided with a rectifying and integrating circuit and
a comparator (both not shown), and a simulation and howling detection signal is output. Then,
since "L" is input to one side of the AND 2262, "L" is output from the AND 2262 this time, and
"H" is output as the shifter signal (FIG. 11m). Receiving this, the terminal of the analog switch
2043 is shorted.
[0049]
Then, similarly, “L” is output from the AND 2263 of the shifter signal to be generated next,
and “H” is output as the shifter signal. The attenuator unit 92 receives the “H” of the shifter
signal, and the terminal of the analog switch 2044 remains shorted. Hereinafter, similarly, the
terminals of the analog switches 2045 to 7 are shorted.
[0050]
08-05-2019
13
In this way, as shown in FIG. 10, the terminals of the analog switches 2043 to 2047 of the
attenuator unit 92 are connected, and the circuit loop is fixed at an attenuation that generates
approximately the same howling P 'as the howling P of the main circuit.
[0051]
In this state, when the volume of the master volume 18 is lowered, the simulation master volume
88 is also lowered synchronously, and the howling P 'in the simulation circuit 9 is stopped.
The simulation howling detection circuit 36 detects this stop signal, outputs a control signal C
(stop control signal), and connects the terminal of the changeover switch 70 to s1. As a result,
the howling cut filter 28 is turned off, so that the audio signal does not pass through the howling
cut filter 28 and the high frequency component thereof is not removed.
[0052]
In this embodiment, the howling P is detected based on the output of the power amplifier 8, but
based on any signal of the signal path, for example, any signal of the microphone 2, the head
amplifier 4 or the microphone amplifier 6. Howling P may be detected.
[0053]
Further, in this embodiment, the howling elimination filter means 28 is provided between the
amplifier 22 and the gain adjustment means 24. However, for example, between the voice input
means 20 and the amplifier 22 any means of the signal path may be provided. It may be
provided in
[0054]
According to the first aspect of the present invention, the howling elimination filter means
(howing cut filter) is provided at a predetermined portion of the audio signal amplifying device,
and the operation is started by the start control signal. Stop the operation to remove the howling
generated in the audio signal.
When the howling detection means detects howling generated in the audio signal, it outputs a
08-05-2019
14
howling detection signal and outputs a start control signal to the howling removal filter means.
[0055]
The simulation amplifier has substantially the same frequency characteristics as the amplifier.
The simulation / gain adjustment means receives the output of the simulation amplifier and
adjusts the gain in conjunction with the gain adjustment means. The simulation howling
detection means detects whether or not howling has occurred in the circuit loop formed by the
simulation amplifier and the simulation gain adjustment means, and outputs a simulation
howling detection signal when the occurrence of howling is detected. Do. The loop coupling
degree adjusting means (automatic attenuator) is a means inserted in the circuit loop formed by
the simulation amplifier and the simulation gain adjusting means to adjust the degree of coupling
of the circuit loop, the howling detection means In response to the detection signal, the degree of
loop coupling is sequentially increased from the minimum, and fixed to the degree of loop
coupling upon receiving the simulation howling detection signal from the simulation howling
detection means.
[0056]
Then, the simulation howling detection means detects the simulation howling detection signal
and then outputs a stop control signal to the howling removal filter means when it detects a stop
of the howling.
[0057]
Therefore, when the howling occurs in the audio signal, it is automatically removed, and when
the howling is stopped while the howling removal filter means 28 is operating, the high
frequency characteristics are not activated. Can be prevented, and the sound quality can be
improved.
As a result, it is possible to provide an audio signal amplifier that improves sound quality while
effectively eliminating howling.
08-05-2019
15
Документ
Категория
Без категории
Просмотров
0
Размер файла
25 Кб
Теги
jph06283949
1/--страниц
Пожаловаться на содержимое документа