JPH1175286A - Automatic variable gain device in microphone signal amplifier system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a gain of a microphone signal amplifier system properly and automatically. SOLUTION: In the automatic variable gain equipment, a signal strength detection section 13 detects a signal strength of a song signal S1 for a prescribed period and holds a maximum signal strength detection results and uses a signal gain setting section 15 to set a gain of a signal amplifier section 12 amplifying the song signal S1 to be a prescribed gain corresponding to the maximum signal strength detection result, when a maximum signal strength subject to holding is high, the signal is amplified at a small gain and conversely when the holding maximum signal strength is small, the signal is amplified at a high gain, resulting that a song signal S2 with proper signal strength and proper gain is automatically adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic gain varying device in a microphone signal amplifying system, and more particularly to a signal intensity adjustment degree suitable for an input audio signal obtained from a microphone in accordance with the level of audio input to the microphone. The technology for automatically setting the

[0002]

2. Description of the Related Art In a karaoke apparatus, for example, a singing signal (input voice signal) obtained from a microphone in accordance with a singing voice input (voice input) to a microphone is amplified by a microphone signal amplifying system and then mixed by a mixing signal amplifying system. After being mixed with the accompaniment signal from the karaoke sound source, it is sent to the speaker. The singer's song flows from the speaker with accompaniment. In the case of this karaoke apparatus, an unspecified number of singers often take turns and sing with a microphone in their place, but the voice volume of many singers varies widely and individual differences are large. In general, the difference in voice volume between a loud and a loud person is about 10 dB, and the difference in voice volume between an extremely loud and a loud person is about 20 dB.

Therefore, if the gain of the microphone signal amplification system is appropriate for a person with a small voice, the singing of a person with a large voice will be over-amplified and the volume will be excessive if left untouched.
The listener is uncomfortable. Conversely, if the gain of the microphone signal amplification system is appropriate for a loud voice person, the song of a low voice person will not be amplified sufficiently and the volume will be insufficient, and the song will not be heard well, which is not interesting. Therefore, in a conventional karaoke apparatus, a gain adjustment volume (variable resistor) of a manual adjustment method is provided in the microphone signal amplification system, and the knob of the volume is manually turned according to the volume of the singer's voice, to thereby control the microphone signal amplification system. Adjust the gain,
Sound is output from the speaker at an appropriate volume.

[0004]

However, it is quite troublesome to adjust the gain of the microphone signal amplifying system by the gain adjusting volume of the conventional manual adjustment method. In particular, when the singer changes one after another, the gain adjustment volume must be frequently turned, which is quite troublesome. On the other hand, if the gain adjustment of the microphone signal amplifying system is not good, the loud sound reverberating in the room may buy other customers' dissatisfaction or the room may not have enough singing voice, and the customers who come to the store looking forward to singing It is not easy to neglect the gain adjustment of the microphone signal amplifying system because it makes you feel bad.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an automatic gain variable device in a microphone signal amplifying system in which accurate gain adjustment of the microphone signal amplifying system is automatically performed.

[0006]

In order to solve the above-mentioned problems, an automatic gain varying device in a microphone signal amplifying system according to the first aspect of the present invention provides an automatic gain varying device for converting an input audio signal obtained from a microphone with an audio input to the microphone. Signal strength adjusting means for adjusting the signal strength, signal strength detecting means for detecting the signal strength of the input audio signal from the microphone for a predetermined period, and a signal for holding the maximum signal strength detection result detected by the signal strength detecting means Strength holding means, and adjustment degree setting means for setting the degree of adjustment of the signal strength in the signal strength adjustment means to a certain degree of adjustment after the lapse of the predetermined period in accordance with the maximum signal strength detection result held by the signal strength holding means. ing.

According to a second aspect of the present invention, in the automatic gain varying device in the microphone signal amplifying system according to the first aspect, the degree of adjustment setting means switches on and off the switches by combining a plurality of switches and resistors. And a variable resistance variable resistance means whose resistance value discretely changes with the change of the resistance value by selecting the ON / OFF state of the switch performed according to the held maximum signal strength detection result. It is configured to set a certain degree of adjustment.

According to a third aspect of the present invention, in the automatic gain variable device in the microphone signal amplifying system according to the first aspect, the adjustment degree setting means includes a variable resistance means whose resistance value changes continuously. Then, by setting the set resistance value of the variable resistance means in accordance with the held maximum signal strength detection result, a constant adjustment degree of the signal strength adjustment means is set.

[0009]

Next, the operation when the gain is adjusted by the automatic gain variable device (hereinafter abbreviated as "automatic gain variable device" as appropriate) in the microphone signal amplification system of the present invention will be described. In the automatic variable gain device according to claim 1, first,
The signal strength detection means detects the signal strength of the input audio signal from the microphone for a predetermined period, and the signal strength holding means holds the maximum signal strength detection result detected by the signal strength detection means.
After a lapse of a predetermined period in which signal strength detection is performed, the adjustment degree setting means adjusts the signal strength adjustment degree of the signal strength adjustment means according to the maximum signal strength detection result held by the signal strength holding means. The degree of adjustment is automatically set, and thereafter, the signal strength of the input audio signal is adjusted at the set constant degree of adjustment. When the held maximum signal strength is large, a small fixed degree of adjustment is set, and when the held maximum signal strength is small, a large fixed degree of adjustment is set.

[0010] Therefore, for a large input voice signal having a large voice volume, the signal strength is adjusted to a low degree by the signal strength adjusting means. On the other hand, a small input voice signal having a small voice volume is sufficiently amplified by the signal strength control means with a high degree of adjustment. Be avoided. That is, in the automatic gain varying device according to the present invention, the voice level is detected in real time for a predetermined period, and the signal intensity adjusting means for adjusting the signal intensity of the input voice signal in accordance with the detected actual voice volume is adjusted. By automatically setting the degree, accurate automatic gain adjustment of the microphone signal amplification system is realized.

In the case of the automatic variable gain device according to the second aspect, a plurality of switches and resistors are combined, and the ON / OFF state of the switches is determined.
The resistance value of the variable resistance means is selected according to the maximum signal strength detection result held by the signal strength holding means based on the on / off state of the switch of the variable resistance variable resistance means in which the resistance value discretely changes according to the off state. A change occurs, and the degree of adjustment of the signal strength of the signal strength adjusting means is set to a constant degree of adjustment by the change in the resistance value. In the automatic gain varying device according to the second aspect, since the adjustment degree setting means can be easily realized by a combination of a plurality of switches and resistors, the invention is easily implemented.

In the automatic gain varying device according to the third aspect, the set resistance value of the variable resistance means whose resistance value changes continuously is selected in accordance with the maximum signal strength detection result held by the signal strength holding means. Accordingly, the degree of adjustment of the signal strength of the signal strength adjusting means is set to a constant degree of adjustment. In the automatic gain varying device according to the third aspect, the degree of adjustment of the signal strength of the signal strength adjusting means for adjusting the signal strength of the input audio signal is changed by the variable resistance means which does not require a switch. The degree of adjustment of the signal strength can be set finely.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the automatic gain varying device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of a karaoke apparatus in which the automatic gain varying device according to the embodiment is incorporated, and FIG. 2 is a block diagram showing the overall configuration of the automatic gain varying device of the embodiment. The karaoke apparatus shown in FIG. 1 includes a microphone 1, a microphone signal amplifying system 2 for amplifying a singing signal (input voice signal) obtained from the microphone 1 in accordance with a singing voice input (voice input) to the microphone 1, a recording tape or a disk. An accompaniment sound source device 3 for reading and outputting an accompaniment signal stored in a memory medium such as the above, a mixing signal amplifying system 4 for superimposing a song signal and an accompaniment signal, a speaker 5, and the like.

The microphone signal amplification system 2 first amplifies a weak singing signal from the microphone 1 to a certain level (for example, amplifies it by about 30 dB).
An automatic gain adjusting device 7 for performing automatic gain adjustment on the singing signal sent from the head amplifier 6 in accordance with the volume of the singer, and a microphone amplifier 8 having an amplifying function and a sound quality adjusting function and serving as an intermediate amplifier. And are connected in series. In FIG. 1, the microphone 1
, The configuration from the microphone 1 to the automatic gain variable device 7 is installed in only one row. Usually, the configuration from the microphone 1 to the automatic gain variable device 7 is installed in a plurality of rows, and only one microphone amplifier 8 is installed. In many cases, a plurality of singing signals obtained by the microphones 1 are gain-adjusted by the automatic gain varying device 7 and then superimposed by the microphone amplifier 8.

The mixing signal amplifying system 4 includes a mixing amplifier 9 for superposing a song signal sent from the microphone amplifier 8 and an accompaniment signal (non-microphone signal) sent from the accompaniment tone generator 3, and a mixing signal amplifying system 4.
And a power amplifier 11 for power-amplifying a mixed signal of a singing signal and an accompaniment signal so that the speaker 5 can sound.
And are connected in series. The output of the power amplifier 11 is sent to the speaker 5. For the manual gain adjustment volume 10, for example, a variable resistor for normal volume adjustment is used, and knob adjustment is performed so that sound flows from the speaker 5 at an appropriate volume with respect to the input of a standard signal. Will be The knob adjustment of the gain adjustment volume 10 is rarely readjusted once performed.

Next, the configuration of the automatic gain varying device 7 provided in the microphone signal amplification system 2 will be further described as a feature of the present invention. As shown in FIG. 2, the automatic gain varying device 7 includes a signal amplifying section (signal strength adjusting means) 12 for amplifying the song signal S1 output from the head amplifier 6, and a signal strength of the song signal S1 for a predetermined period. A signal strength detection unit 13 for detecting only for a period (for example, 10 seconds after the beginning of singing), a signal strength holding unit 14 for holding at least a maximum signal strength detection result detected by the signal strength detection unit 13, and after a predetermined period has elapsed. Indicates the gain (degree of adjustment of the signal strength) in the signal amplifying section 12 and the signal strength holding section 14
Signal gain setting unit (adjustment degree setting means) 1 for setting a constant gain according to the maximum signal strength detection result held by
5 is provided.

In the automatic gain varying device 7, when the held maximum signal intensity is large, a small constant gain is set in the signal amplifier 12, and the large song signal S1 is amplified while being kept low. Conversely, when the held maximum signal strength is small, a large constant gain is set in the signal amplifier 12, and the small song signal S1 is sufficiently amplified. That is, the song signal S1 that is too large is weakened, and the song signal S1 that is too small is strengthened and output as an appropriate song signal S2.

The automatic gain varying device 7 detects the voice level of the current singer in real time for a certain period, and amplifies the singing signal S1 in accordance with the detected actual voice volume.
By automatically setting the gain of the microphone 2, the automatic gain adjustment of the microphone signal amplifying system 2 is realized, the singing signal S1 is adjusted to an intensity corresponding to the singer's voice volume, and the next microphone is set as an appropriate singing signal S2. The configuration of the automatic gain varying device 7 will be specifically described below.

FIG. 3 shows the signal amplifier 1 of the automatic gain varying device 7.
2 and a block diagram showing a detailed configuration of a signal gain setting unit 15, FIG. 4 is a block diagram showing a detailed configuration of a signal strength detection unit 13 and a signal strength holding unit 14 of the automatic gain varying device 7,
FIG. 5 is a graph showing a singing signal and a signal obtained by envelope detection of the singing signal. FIG. 6 is a graph showing signal waveforms of the signal strength detection unit 13 and the signal strength holding unit 14.

As shown in FIG. 3, the signal amplifying section 12 is composed of a non-inverting type amplifier having the same input and output polarities composed of an operational amplifier OP1 and feedback resistors RS1 to RS3. On the other hand, the signal gain setting unit 15 includes a series connection of a switch SW1 and a resistor R1, a series connection of a switch SW2 and a resistor R2,..., A series connection of a switch SWK and a resistor RK,. A discrete variable resistor (discrete variable resistor means) connected in parallel with a connector is provided, and switches SW1 to SW are provided by a signal strength holding unit 14 (described in detail later).
The resistance value is discretely changed by selecting the ON / OFF state of N. The switch S
Semiconductor switches and micro relays are used for W1 to SWN.

As will be described later in detail, the discrete variable resistor as the signal gain setting unit 15 is a feedback resistor RS
3, and the gain of the signal amplifying unit 12 changes as the resistance between the feedback resistor RS2 and the signal line SL changes according to the resistance change of the variable resistor.

The output of the signal amplifying unit 12 is output via a preset volume 16 for voltage division. The manual preset volume 16 is manually turned to adjust in advance so that the output of the signal amplifying unit 12 is appropriately divided. This preset volume 16
Is rarely readjusted once performed.

As shown in FIG. 4, the signal intensity detector 13 detects and rectifies the singing signal S1 to obtain a single-wave envelope signal S3, and the N comparators CP1 to CP.
N, a comparator CPa for detecting that the singing signal S1 is being generated, a multivibrator MB1, and a timer TMa for clocking a predetermined period Ta.

As shown in FIG. 5A, when the singing signal S1 with a large voice volume is input, the envelope detecting section 17
As shown in FIG. 5B, the envelope signal S having a high signal strength is obtained.
5 is output. Conversely, as shown in FIG. 5C, when the singing signal S1 with a small voice volume is input, as shown in FIG. 5D, the envelope signal S3 having a low signal intensity is output. Is output.
For both the singing signal S1 and the envelope signal S3, the signal strength increases as the voice volume increases, and the signal strength of the envelope signal S3 corresponds to the signal strength of the singing signal S1. Therefore, detecting the signal strength of the envelope signal S3 means detecting the signal strength of the song signal S1. In FIG. 5, each waveform diagram is shown as a step waveform for convenience of drawing, but it is needless to say that these waveforms are continuous waveforms that change smoothly.

As shown in FIG. 6, each of the output signals S4 to S7 of the comparators CP1 to CPN has a constant value (threshold voltage value) in which the signal strength (voltage value) of the envelope signal S3 is predetermined. While the voltage exceeds V1 to VN, it is at the H level (however, V1 <V2 <... <VK <... VN). In the illustration of FIG. 6 and the following description, for convenience, it is assumed that there are only four comparators CP1, CP2, CPK, and CPN and four corresponding constant values V1, V2, VK, and VN.

The output signal S8 of the comparator CPa is H while the magnitude of the envelope signal S3 exceeds the noise level.
Level, and the output signal S9 of the multivibrator MB1 maintains the H level for a predetermined period every time the output signal S8 changes from the L level to the H level. Therefore, if the output signal S8 shifts from the L level to the H level one after another until a certain period elapses, the output signal S9 continuously maintains the H level as shown in FIG. And the singer finishes singing No. 1,
When the singing signal S1 disappears and the envelope signal S3 also disappears, and the output signal S8 of the comparator CPa does not shift from the L level to the H level during a certain period, the output signal S9 of the multivibrator MB1 becomes L for the first time. Return to level. That is, while the singer is singing each number (one chorus) of the song, the output signal S9 of the multivibrator MB1 is
Keeps the H level, and the output signal S9 is at the L level while the song is interrupted by the prelude, interlude, or later. Therefore, the output signal S9 changes from the L level to the H level.
The transition to the level is the timing of the beginning of the singing of one chorus.

When the output signal S9 shifts from the L level to the H level, the timer TMa starts timing, and at the same time, the output signal S10 of the timer TMa shifts from the L level to the H level as shown in FIG. H during the timing of
When the level is maintained and the timer TMa measures a predetermined time Ta (for example, about 10 seconds), the output signal S10 returns from the H level to the L level. The output signal S10 of the timer TMa is inverted by the inverting unit 18. Of course, the reversing unit 18
Is an inverted signal of the H level and the L level of the output signal S10.

On the other hand, the signal strength holding unit 14
1 to RAN, latches RB1 to RBN,
AND (AND circuit) AN1 to ANN are provided. The latches RA1 to RAN output the output signal S10 of the timer TMa.
Performs a latch operation while the output signal S1 is at the H level.
The latch operation is canceled in accordance with the transition of 0 to the L level.
On the other hand, the latches RB1 to RBN are connected to the multivibrator M
The latch operation is performed while the output signal S9 of B1 is at the H level, and the latch operation is canceled with the transition of the output signal S9 to the L level. And (AND circuits) AN1 to AN1
ANN outputs the output signals S12 to S12 of the latches RB1 to RBN.
The operation is such that when both the signal 15 and the output signal S10 of the inverting section 18 are at the H level, the signal becomes H level;

As shown in FIG. 6, latches RA1 to RAN
Output signals S12 to S15 are output from the comparator CP of the preceding stage.
If there is a transition from 1 to CPN to the H level, this is latched and the transition is made to the H level. Then, the latches RA1 to RA
In response to the shift of the N output signals S12 to S15 to the H level, the output signals S16 to S19 of the latches RB1 to RBN also shift to the H level. When the output signal S10 of the timer TMa shifts to the L level, the output signals S12 to S15 return to the L level, but since the output signal S9 of the multivibrator MB1 maintains the H level, the latches RB1 to
The RBN output signals S16 to S19 maintain the H level.

As shown in FIG. 6, before the predetermined time Ta elapses, the output signal S11 of the inverting section 18 is always at L level, so that the output signals S16 to S16 of the latches RB1 to RBN are output.
Even if 19 is at the H level, ANDs AN1 to AN1
Although the N output signals S20 to S23 are at the L level, the output signal S11 of the inverting unit 18 is at the H level after the elapse of the predetermined time Ta, so that the output signals S1 of the latches RB1 to RBN are output.
If there is an H level in 6 to S19, AND
The output signals S20 to S23 of 1 to ANN shift to the H level.

The output signals S20 to S23 of these ANDs AN1 to ANN are respectively guided to switches SW1 to SWN of the signal gain setting section 15, as shown in FIG. Will be. In the case of the embodiment, the output signals S20 to S23 are L
When the level is at the level, the switches SW1 to SWN are turned on, and when the output signals S20 to S23 are at the H level, the switches SW1 to SWN are turned off.

Before the elapse of the predetermined time Ta, the output signal S20
To S23 are all at the L level,
SWN is turned on. Therefore, the gain AG of the signal amplifier 12
AG = [RS1 + RS2 + (RS3 // R1 // R2 /
//.../RK//RN)]÷[RS2+(RS3//R
1 // R2 //...// RK // RN)], and the signal amplifier 12 is set to the highest gain (maximum gain). After the elapse of the predetermined time Ta, the value of the held maximum signal strength becomes very large, and the output signals S20 to S20
23 are all at H level, the switches SW1 to SWN
Are all turned off. Therefore, the gain AG of the signal amplifier 12
AG = (RS1 + RS2 + RS3) ÷ (RS2 + RS
3) The signal amplifier 12 is set to the lowest gain (minimum gain). Note that RS1 to RS3 in the above equation
And R1 to RN indicate the resistance values of the corresponding resistors.
Indicates a parallel connection of resistors. Therefore, the output signals S20 to S20 which become H level according to the detection result of the maximum signal strength of the song signal
23, the number of signals at the H level is different, and the gain AG of the signal amplifying section 12 is changed according to the number of signals at the H level.
Is set between the maximum gain and the minimum gain. Before the predetermined time Ta elapses, the gain need not always be set to the maximum gain, but may be set to an intermediate gain.

Summarizing the above, all the comparators CP1 to CPN having threshold values up to the maximum signal strength of the envelope signal S3 shift to the H level until the predetermined time Ta elapses, and After the elapse of time Ta, H
AND1 corresponding to the comparator that has shifted to the level
ＡＮANN output signals S20〜S23 are maintained at H level and switches SW1ＳＷSWN are turned off to change the resistance value, so that signal amplifying unit 12 adjusts the maximum signal strength detection result of song signal S1 for a predetermined period. Is automatically set.

Next, the automatic gain setting operation by the automatic gain varying device 7 having the above configuration will be described with reference to the drawings. FIG. 7 is a flowchart showing the flow of the automatic gain setting operation of the embodiment. [Step ST1] Until the input of the song signal S1 starts,
The output signals S20 to S23 of the ANDs AN1 to ANN are all at the L level, the switches SW1 to SWN are all on, and the gain setting of the gain AG of the signal amplifier 12 is the maximum gain.

[Step ST2] With the start of the input of the song signal S1, an envelope signal S3 is generated, the output signal S9 of the multivibrator MB1 shifts to the H level, and the output signal S10 of the timer TMa also shifts from the L level. The level shifts to the H level, and the timing of the predetermined time Ta, which is the signal strength detection time of the song signal S1, starts.

[Step ST3] Until the predetermined time Ta elapses, the detection of the signal strength of the singing signal S1 is executed and the output signals S20 to S2 of the ANDs AN1 to ANN are executed.
3 remain at the L level, the gain AG of the signal amplifier 12 also remains at the maximum gain.

[Step ST4] The maximum signal strength detection result is held at the same time when the predetermined time Ta elapses, and the corresponding one of the output signals S20 to S23 of the ANDs AN1 to ANN maintains the H level.

[Step ST5] ANDs AN1 to ANN
Of the output signals S20 to S23 are sent to the switches SW1 to SWN, and only the corresponding switches are turned from on to off.

[Step ST6] Switches SW1 to SW
The gain AG of the signal amplifying unit 12 is set to a constant gain corresponding to the maximum signal strength detection result due to the change in the feedback resistance accompanying the change in the ON / OFF state of N.

[Step ST7] The song is interrupted and the song signal S
1 disappears, the output signals S2 of AND1 to AN1
0 to S23 all return to the L level.

[Step ST8] All ANDs AN1 to AN
With the return of the N output signals S20 to S23 to the L level, all the switches SW1 to SWN are turned on, and the set gain of the gain AG of the signal amplifier 12 also returns to the maximum gain. [Step ST9] When the song is restarted and the input of the song signal S1 is started again, the operations in and after step ST2 are repeated. Of course, if there is no re-input of the song signal S1, the operation ends.

Next, another embodiment of the automatic gain varying device according to the present invention will be described. FIG. 8 is a block diagram showing a configuration of an automatic gain varying device according to another embodiment, and FIG. 9 is a graph showing signal waveforms of respective parts. Since other configurations are substantially the same as those of the previous embodiment, Illustration and explanation of common parts are omitted. As shown in FIG. 8, in an automatic gain varying device according to another embodiment, an attenuator (signal strength adjusting means) 21 using a variable resistor 22 having a continuously changing resistance value, and a maximum signal strength to be held. An attenuation setting unit (adjustment setting means) 23 for selecting a set resistance value of the variable resistor 22 in accordance with the detection result and setting a constant attenuation (adjustment of signal intensity) of the attenuator 21; ing.

As shown in FIG. 8, the song signal S1 is applied between the fixed terminals 22a and 22b of the variable resistor 22, and the song signal S2 is extracted from the movable terminal 22c of the variable resistor 22. The movable terminal 22c moves according to the rotation direction of the motor 26. The amount of movement of the movable terminal 22c is proportional to the amount of rotation of the motor 26. The singing signal S1 is divided according to the stop position (set resistance value) of the movable terminal 22c and output as the singing signal S2. In this embodiment, the attenuation can be continuously changed by the variable resistor 22, so that the signal strength can be finely adjusted.

As described above, since the constant attenuation (adjustment of the signal intensity) set by the attenuator 21 is determined by the stop position of the movable terminal 22c, the attenuation setting unit 23 sets the maximum signal to be held. Movable terminal 22c according to the strength detection result
Is performed to select the stop position (i.e., the set resistance value). Hereinafter, the configuration of the attenuation setting unit 23 will be described more specifically.

At first, the attenuation degree setting unit 23
c (preset control of the movable terminal 22c) to move the movable terminal 22c to the initial stop position (for example, the center position), and control to move the movable terminal 22c as necessary in accordance with the held maximum signal strength detection result (the movable terminal 22c (This set control).

The outline of the preset control of the movable terminal 22c is as follows. The amount of rotation of the motor 26 for moving the movable terminal 22 c is controlled by the motor 2 via the motor driver 25.
6 is determined by the output signal of the controller 24 transmitted to the controller 6. A slip mechanism is provided at a connection portion between the movable terminal 22c and the motor 26, and the movable terminal 22c is
When reaching the end point on the a side or the end point on the fixed terminal 22b side, even if the motor 26 is rotating, the slip mechanism operates and the movable terminal 22c stops at the end point. Therefore, when presetting the movable terminal 22c,
Regardless of the position of 2c, an output signal is provided from the controller 24 to the motor 26 so as to always move to the end point, and after moving to the end point, just after the end point,
An output signal is provided from the controller 24 to the motor 26 so that the motor 26 rotates in the reverse direction by the amount that the movable terminal 22c returns to the center position.

When the singer enters the interlude period after singing No. 1 or turns on the power, a signal for presetting the movable terminal 22c is sent to the controller 2.
4 to the motor 26, the movable terminal 22c is always returned to the initial stop position and waits.

The main set control of the movable terminal 22c is as follows. As in the case of the previous embodiment, the signal intensity is detected based on the envelope signal S3 only during the predetermined period Ta, and the output signals S20 to S23 of ANDs AN1 to ANN are obtained, as shown in FIG. Are input to the timers TM1 to TMN. Timers TM1 to TMN are AND1 to AN
When an H-level output signal is received from NN, the clocking operation is started, while the output signals S24 to S27 of the timers TM1 to TMN are at the H level during the clocking operation. Timer TM1
To TMN output signals S24 to S27
Sent to The controller 24 includes timers TM1 to TM
Among the output signals S24 to S27 of the MN, only the output signal of the timer connected to the AND (AND circuit) corresponding to the maximum signal strength is selected and sent to the motor 26.

H level period T of output signals S24 to S27
The length of b1 to TbN is directly proportional to the distance between the initial stop position of the movable terminal 22c and the stop position corresponding to a certain degree of attenuation. Further, when moving from the initial stop position to the fixed terminal 22a side and when moving to the fixed terminal 22b side,
Since the rotation direction of the motor 26 is reversed, the fixed terminals 22a
When moving to the side, the controller 24 inverts the output signal of the timer to the negative polarity and then sends it out. Therefore, when the detected signal strength value is the smallest (and A
When only the output signal of N1 is at H level, the longest positive control signal is given to the motor 26, and when the detected signal strength value is the largest (and AN1 to AN1 to A1).
NN output signals are all at H level), the longest negative control signal is given to the motor 26.
However, when an output signal is output from the timer in which the set position is the initial stop position, the controller 24 does not send the output signal to the motor 26. This is because, at this time, it is not necessary to move the movable terminal 22c from the initial stop position.

Further, the attenuation setting section 23 has a structure necessary for the preset control for returning the movable terminal 22c moved by the above-mentioned main set control to the initial stop position during the interlude period.
It is provided in. For example, until the singer finishes singing No. 1 and starts singing No. 2, as shown in FIG.
Although the output signal S9 of the multivibrator MB1 changes from H level to L level, the movable terminal 22c is returned to the initial stop position during this L level period.

Output signal S9 of multivibrator MB1
Is inverted by the inverting unit 27, and the output signal S2 of the inverting unit 27 is
8 is delayed for several microseconds by the delay unit 28 and then sent to the latch 29. The output signal S29 of the delay unit 28 becomes the clock signal of the latch 29, and the output signal S2 of the inversion unit 27
8 becomes the reset signal, and as a result, the output signal S
30 is as shown in FIG. The delay of several microseconds by the delay unit 28 is for keeping the operation of the latch 29 normal.

Then, the output signal S30 of the latch 29 is sent to the timer 30, and the timer 30 outputs the output signal S31 which becomes H level for a certain period Tc to the analog inverting section 31 to invert to the negative polarity. The output signal S32 of the analog inverting unit 31 is further supplied to the analog synthesizing unit 32.
Sent to On the other hand, the output signal S31 of the timer 30 is also sent to the inverting unit 33 and is inverted. The output signal S32 of the inverting unit 33 is sent to the timer 34, and the timer 30 outputs to the analog synthesizing unit 32 an output signal S34 that goes high for a certain period Td.

The analog synthesizing unit 32 outputs the output signals S32,
S34 is synthesized and an output signal S35 is sent to the controller 24. The output signal S35 is sent from the controller 24 to the motor 26. The rotation of the motor 26 due to the minus signal portion of the fixed period Tc of the output signal S35 causes the movable terminal 22 to rotate.
After moving c to the end point on the fixed terminal 22a side, the movable terminal 22c is returned to the center initial stop position by the reverse rotation of the motor 26 by the plus signal portion of the subsequent fixed period Td to perform the preset control of the movable terminal 22c. Complete. When the power is turned on, the same as the output signal S35, for a certain period T
A signal in which a minus signal portion of c and a plus signal portion of Td for a certain period of time are automatically output to the motor 26, thereby executing preset control of the movable terminal 22c.

Next, an automatic gain setting operation by another embodiment device having the above configuration will be described with reference to the drawings. FIG. 10 is a flowchart showing the flow of the automatic gain setting operation of the device of another embodiment. [Step STA] Controller 24
Sends a signal for preset control to the motor 26, and the movable terminal 22c of the variable resistor 22 moves to the center initial stop position.

[Step STB] With the start of input of the song signal S1, detection of the signal strength of the song signal S1 is executed for a predetermined time Ta.

[Step STC] The maximum signal strength detection result is held as soon as the predetermined time Ta elapses.

[Step STD] The output signal of the timer corresponding to the result of detection of the maximum signal strength is sent from the controller 24 to the motor 26 as a set control signal.

[Step STE] The motor 26 rotates by the required amount in accordance with the set control signal and the movable terminal 22c moves, so that the attenuation of the attenuator 21 becomes a constant attenuation corresponding to the maximum signal strength detection result. Is set.

[Step STF] The song is interrupted and the song signal S
When 1 disappears, the output signal S9 of the multivibrator MB1 becomes L level.

[Step STG] Multivibrator M
As the output signal S9 of B1 becomes L level, a signal for preset control is sent from the analog synthesis unit 32 to the controller.

[Step STH] The motor 26 rotates according to the preset control signal from the controller 24,
The movable terminal 22c of the variable resistor 22 returns to the center initial stop position.

[Step STI] When the song is restarted and the input of the song signal S1 is started again, the operations in and after step STB are repeated. Of course, if there is no re-input of the song signal S1, the operation ends.

(1) In the above embodiment, the automatic gain variable device is applied to the karaoke device. However, the automatic gain variable device in the microphone signal amplification system of the present invention may be applied to a device other than the karaoke device. Needless to say.

(2) The signal strength detector 13, signal strength holding unit 14, and signal gain setting unit 15 are not limited to those having the illustrated circuit configuration. Further, in the embodiment shown in FIG. 3, a variable resistor may be used instead of the combination of the switch and the resistor.

[0065]

As is apparent from the above description, according to the automatic gain varying device in the microphone signal amplifying system according to the first aspect of the present invention, the maximum signal strength of the input voice signal obtained from the microphone during a predetermined period is detected. • After a predetermined period of time after being held, the degree of adjustment of the signal strength adjusting means for adjusting the signal strength of the input audio signal is automatically set to a constant degree of adjustment corresponding to the held maximum signal strength. . That is, the signal intensity is adjusted with a low degree of adjustment for a large input audio signal having a large voice volume, so that even a person with a large voice can avoid a situation in which a sound is excessively loudly output from a speaker. Conversely, since the signal intensity is adjusted with a high degree of adjustment for a small input voice signal having a small voice volume, it is possible to avoid a situation in which even a person with a small voice outputs sound due to insufficient volume from a speaker. Thus, according to the present invention,
Regardless of the volume of the voice of the person who uses the microphone, since the sound is output from the speaker at an appropriate volume, accurate automatic gain adjustment of the microphone signal amplification system is realized.

In the case of the automatic gain varying device according to the second aspect, the degree of adjustment of the signal strength adjusting means for adjusting the signal strength of the input audio signal is determined by turning on / off the switches by combining a plurality of switches and resistors. Accordingly, the present invention can be easily implemented because it can be easily realized by the discrete variable resistance means whose resistance value changes discretely.

In the automatic gain varying device according to the third aspect, the degree of adjustment of the signal strength adjusting means for adjusting the signal strength of the input audio signal is changed by the variable resistance means, so that the degree of adjustment can be set finely. can do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a karaoke apparatus using an automatic gain varying device according to an embodiment.

FIG. 2 is a block diagram illustrating an overall configuration of an automatic gain varying device according to an embodiment.

FIG. 3 is a block diagram showing a signal amplifying unit and a signal gain setting unit of the device according to the embodiment.

FIG. 4 is a block diagram illustrating a signal strength detection unit and a signal strength holding unit of the apparatus according to the embodiment.

FIG. 5 is a graph showing a song signal and an envelope signal obtained by performing envelope detection on the song signal.

FIG. 6 is a graph showing signal waveforms in a signal strength detection unit and a signal strength holding unit.

FIG. 7 is a flowchart showing a flow of an automatic gain setting operation of the embodiment.

FIG. 8 is a block diagram illustrating a configuration of a main part of a device according to another embodiment.

FIG. 9 is a graph showing a signal waveform of each unit of another embodiment device.

FIG. 10 is a flowchart illustrating a flow of an automatic attenuation setting operation according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Microphone 7 ... Automatic gain variable device 12, 21 ... Signal amplification part 13 ... Signal strength detection part 14 ... Signal strength holding part 15, 23 ... Signal gain setting part 22 ... Variable resistors R1-RN ... Resistance S1 ... Song signal

Claims (3)

[Claims] 1. A signal strength adjusting means for adjusting a signal strength of an input voice signal obtained from a microphone in accordance with a voice input to a microphone, and a signal strength detecting a signal strength of the input voice signal from the microphone for a predetermined period. Detection means, signal strength holding means for holding the maximum signal strength detection result detected by the signal strength detection means,
A microphone signal amplifier comprising an adjustment degree setting means for setting the adjustment degree of the signal strength in the signal strength adjustment means to a constant adjustment degree in accordance with the maximum signal strength detection result held by the signal strength holding means after the lapse of the predetermined period. Automatic gain variable device in the system. 2. The automatic gain varying device according to claim 1, wherein the adjustment degree setting means includes a combination of a plurality of switches and a resistor, and the resistance value is discrete as the switch is turned on and off. A variable resistance variable means is provided which changes to a constant value, and a constant degree of adjustment of the signal strength adjusting means can be set by a resistance value change by selecting an ON / OFF state of a switch performed according to the held maximum signal strength detection result. An automatic gain varying device in a microphone signal amplification system configured to perform. 3. The automatic gain variable device according to claim 1, wherein the adjustment degree setting means includes a variable resistance means having a resistance value which continuously changes, and the held maximum signal. An automatic gain variable device in a microphone signal amplifying system configured to set a constant degree of adjustment of a signal intensity adjusting means by selecting a set resistance value of a variable resistance means according to an intensity detection result.