JPS6129205A - Sound quality and sound volume controlling system of sound apparatus - Google Patents

Abstract

PURPOSE:To make loudness control by appropriate and stable correction characteristics by providing emitter grounding amplifier circuits for low frequency range and high frequency range and a diode that applies the output of to a sound quality controlling circuit. CONSTITUTION:Sound volume controlling voltage set in a sound volume controlling voltage source 51 is applied to an input terminal 28, and at the same time, supplied to a transistor TR50. Sound volume controlling voltage from the TR50 is amplified to opposite phase by TRs 40, 46 that form emitter amplifier circuits for low frequency range and high frequency range respectively. Accordingly, when the sound volume controlling voltage is lowered by setting of the voltage source 51, the collector voltage of TRs 40, 46 rises. When the collector voltage of TR40 goes up and the pole of voltage applied to a diode 38 becomes normal direction, the low frequency range controlling voltage impressed to an input terminal 26 goes up, and the low frequency range of sound signals is augmented. Similarly, the high frequency range of sound signals is augmented by rise of collector voltage of TR46. Thus, the loudness control can be performed by appropriate and stable correction characteristics.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a sound quality/volume control method for audio equipment, and more specifically to a loudness control function (as the sound pressure decreases, it becomes difficult to hear low and high frequencies). A function added to compensate for this.In other words, when the volume is raised, the frequency characteristics are almost flat, but when the volume is lowered, the degree of bass and treble enhancement increases.

) is related to a sound quality/volume control method.

[Background of the Invention] □ Conventionally, the volume of audio equipment has been controlled by a variable resistor for volume adjustment, and the sound quality has been controlled by a sound quality adjustment circuit consisting of a resistor and a capacitor. □When performing loudness control using such a circuit, the variable resistor for volume adjustment is linked to the sound quality adjustment circuit, and the characteristics of the filter made up of resistance and capacitance are changed to perform the control as shown on the left.

However, as a recent trend, instead of using a variable resistor or resistance and capacitance to control the volume and sound quality, it is possible to use a volume/sound quality control circuit that can control the volume and sound quality by input DC voltage. It's becoming common.

The volume/sound quality control circuit consists of a volume control circuit and a sound quality control circuit. For example, in the case of a volume control circuit, a DC voltage is input to the circuit, and the volume is increased by increasing the level of the DC voltage. It can be controlled in the direction of lowering K. That is, it is a circuit that allows the volume or sound quality to be easily and freely set to a desired value simply by changing the level of the input DC voltage.

Now, let's consider the case where loudness control is performed using such a volume/sound quality control circuit.

By the way, loudness control is the process of correcting audio signals using certain correction characteristics. It should be determined by how it sounds. Therefore, if the audio output of the audio equipment differs in five ways, such as one with a 5W output or one with an IOW output, naturally the correction characteristics will also differ.

Therefore, although many volume/sound quality control circuits are now being used as single-chip ICs, the circuits necessary to perform loudness control (hereinafter referred to as loudness control circuits) are Because the correction characteristics must be determined based on the audio output, the current situation is that the volume/sound quality control circuit is not integrated into the same chip. In other words, the loudness control circuit is composed of discrete elements (transistors) for devices with different audio outputs.

This can be easily handled by simply changing the resistance (resistance, etc.).

Generally, the following two methods can be considered for controlling loudness using a volume/sound quality control circuit.

One method is to correct the level of the DC voltage input to the sound quality control circuit (hereinafter referred to as the sound quality control voltage) by the DC voltage input to the volume control circuit (hereinafter referred to as the volume control voltage). The second method is to correct the level of the sound quality control voltage using a voltage obtained by rectifying the audio signal after the volume has been controlled. Among these methods, the method of performing loudness control using a volume control voltage has the advantage that the circuit configuration can be simplified compared to the method of performing loudness control using an audio signal.

Therefore, the following describes the case where loudness control is performed using the volume control voltage (.

As a conventional sound quality/volume control method that can perform loudness control using a volume control voltage, for example, Japanese Patent Laid-Open No. 56-61
A circuit such as that described in Japanese Patent Application No. 816 is shown in FIG. 2, and a circuit such as that described in Japanese Unexamined Patent Publication No. 1857-5412 is shown in FIG. 3.

In FIG. 2, VOLI, VOL2. VOL3 is the volume, bass range, and treble range control voltage source, 1゜2.3 is a buffer amplifier, respectively, 4 and 5 are error amplifiers, respectively.
6 is the audio signal input terminal, 7゜8.9 is the volume, respectively.
Bass range and treble range control amplifier; 10 is an output terminal for audio signals after the volume and sound quality have been controlled; 11, 12, 13, 14;
, 15 and 16 are level adjusters, respectively, and sl and s2 are switches, respectively. In this conventional example, loudness control is performed when the switches S1 and 82 are turned on.

Now, the operation will be explained.

As shown in FIG. 2, when switches sl and s2 are off,
The DC voltage set by the volume control voltage source VOL1 (
A volume control voltage) is input to the volume control amplifier 7 via the buffer amplifier 1, and the audio signal input from the input terminal 6 is amplified to a predetermined value to control the volume. Further, the DC voltage (low range control voltage) set by the low range control voltage source VOL 2 is input to the low range control amplifier 8 via the buffer amplifier 2 and the level adjuster 15, and only the low range of the audio signal is controlled. Amplify to the value of Further, the same operation is performed for the treble range. Next, when the switch 51pS2 is on, the volume control voltage output from the buffer amplifier 1 and the bass control voltage output from the buffer amplifier 2 are input to the error amplifier 4 via the level adjusters 11 and 12, respectively. The output thereof is input to the level adjuster 15.

Therefore, when the volume decreases (that is, the volume control voltage decreases due to the setting of the volume control voltage source VOL1), the difference between the volume control voltage and the bass control voltage widens, and the output of the error amplifier 4 increases. , the bass range of the audio signal is enhanced.

The same goes for the treble range.

Although this conventional example has the advantage of being able to perform loudness control according to the bass control voltage and treble control voltage set by the user, the loudness control of the error amplifier 4.5, buffer amplifiers 1, 2, 3, etc. When each component of the circuit is constructed discretely, there are disadvantages in that the number of circuit elements increases, the scale of the entire circuit increases, and the circuit configuration becomes complicated.

Next, FIG. 3 will be explained.

In FIG. 3, 17 is an input terminal for an amplified audio signal, 18 is an output terminal for an audio signal after the amplified volume and sound quality has been controlled, 19,
20.21 are bass range, treble range, and volume control amplifiers, respectively. 22, 23.24 are bass range, treble range, and volume control circuits, respectively. 25 is a volume/sound quality control circuit. 26.27.28
33 is a switch, 34 is an NPN) transistor, 35 is a Zener diode, and 36 is a loudness control circuit.

As shown in FIG. 3, the audio signal is input from the input terminal 17 and output from the output terminal 18. The sound quality and sound in the audio signal are determined by the low range control voltage and the high range control voltage (hereinafter, both are collectively referred to as sound quality control voltage) input to the input terminals 26 and 27, and the input terminal 28. Controlled by volume control voltage.

In this conventional example, loudness control is performed when the switch 33 is in the off state. That is, the volume control voltage set by the variable resistor 31 is applied to the Zener diode 35. resistance 3
Since it is input to the transistor 340 pace through the variable resistor 31, when the volume control voltage is lowered by the variable resistor 31, the 1 resistor 32 and the transistor 34 connected between the variable resistor 29.30 for sound quality control and the ground are input. The parallel impedance with the variable resistor 29,3 becomes large.
The sound quality control voltage determined at the midpoint of 0 is increased to enhance the bass and treble ranges.

In this conventional example, loudness control can be performed with a small number of parts, but since the transistor 34 is used in a location relatively close to the isolation region (that is, a location where the output impedance is high), the DC current amplification factor h? Due to variations in Ei, etc., it is difficult to obtain appropriate and stable characteristics. Also, in order to increase the correction value by loudness control, the resistor 32 must be made relatively large compared to the variable resistor 29.30;
If you increase the volume, if the volume is low, the variable resistor 29.3
There is also the drawback that the variable range of sound quality becomes smaller due to 0, and either the correction value or the variable range is sacrificed.

[Purpose of the invention]

The present invention has been made in order to eliminate the drawbacks of the prior art described above, and therefore, the purpose of the present invention has been expanded, the circuit configuration is simple, and the range of sound quality variable by the user is not sacrificed, and it is suitable and stable. It is an object of the present invention to provide a surface-to-tachi-tachi-boku control system for I2-inside (number -) -1 + 輔伽も茛BE〉Lshi with a correction characteristic that is similar to the above.

[Summary of the invention]

In order to achieve the above object, the present invention provides a sound quality control circuit that controls the bass and treble ranges using a DC control voltage obtained by dividing a constant DC power supply voltage by resistance, and a variable DC voltage source from a volume control voltage source. A sound quality/volume control system for audio equipment comprising a volume control circuit that controls volume by voltage, comprising a common emitter amplifier that receives the variable DC voltage as input, and its amplified output is superimposed on the DC control voltage for sound quality control. A means is provided to boost the bass and treble ranges according to the volume.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

In Fig. 1, the same K as the conventional example shown in Fig. 3 is shown.
The same numbers are given to all of them. Others, 37.43
Hiro each variable resistance, 3B, 44°F; 9-r%M! +
2 ChinatPsu1-41"E11--1."-'JQ-
AI-42.45, 47, 48, 49 are resistors, respectively.
40.46 are NPN ) transistors, 50 is P
NP) transistor, 51 is a volume control voltage source, 54 is a switch, VCCI pV. . 2 is a power supply (provided that VCC1≦VCC2).

First, the operation of the volume/sound quality control circuit 25 surrounded by a dotted line in FIG. 1 will be explained.

First, an audio signal is input from the input terminal 17, and its sound quality is determined by the bass, treble, and volume control voltages applied to the input terminals 26, 27, and 28, respectively.

The respective volumes are controlled and outputted from the output terminal 18. Incidentally, this volume/sound quality control circuit 25 has recently appeared and is often implemented as a one-chip IC as described above.

Next, each control voltage input to the volume/sound quality control circuit 25 is set using a variable resistor for controlling the sound quality (low range, treble range), and using a variable resistor or variable voltage source for controlling the volume. Generally speaking, in this embodiment, the low range control voltage is set by the variable resistor 37, the high range control voltage is set by the variable resistor 43, and the volume control voltage is set by the variable voltage source 51.

The above is the basic operation of volume/sound quality control, and next, the operation of the loudness control circuit will be explained.

The volume control voltage set in the volume control voltage source 51 is applied to the input terminal 28 and is also supplied to the PNP) run raster 500 base.

In addition to impedance conversion, this transistor 50 also serves to compensate for the temperature characteristics of the transistors 40 and 46 used for the next stage KRI and 2 loudness control.

Next, the volume control voltage output from the emitter of the transistor 50 is divided into two parts, one of which is connected to the pace of the transistor 40 for bass control via the resistor 42, and the other to the resistor 4.
8 to the pace of the transistor 46 for controlling the treble range.

The voltage applied to the base of transistor 400 connects transistor 40 and its emitter to ground.
1 and a resistor 39 connected between the collector and the power supply VCC2, the emitter amplifier circuit amplifies the signal in reverse phase and outputs it from the collector of the transistor 40. Similarly, the voltage applied to the base of transistor 46 also applies to transistor 46 and resistor 4.
The signal is amplified in opposite phase by an emitter amplifier circuit constituted by transistors 7 and 45, and outputted from the collector of transistor 46.

Therefore, when the volume control voltage decreases due to the setting of the volume control voltage source 51, the voltages applied to the bases of the transistors 40 and 46 decrease, so that the transistors 40.
The voltage between the collector of No. 6 and ground (hereinafter referred to as collector voltage) increases.

Then, when the collector voltage of the transistor 40 becomes higher than the voltage applied to the input terminal 26, the polarity of the voltage applied to the diode 38 becomes forward, so that the power supply V. o
2, the current flows through resistance 39. Diode 38. variable resistance 37
and applied to input terminal 26, i.e.
The bass range control voltage increases, and the bass range of the audio signal is enhanced. Similarly K.

When the collector voltage of the transistor 46 increases and the polarity of the voltage applied to the diode 44 becomes forward, the treble range control voltage increases and the treble range of the audio signal is enhanced.

Note that the operating range for the volume control voltage in this embodiment is collector resistance 39, 45, emitter resistance 41.47,
It can be arbitrarily selected depending on the relationship between the variable resistors 37 and 43. Therefore, it can be applied not only to a specific volume/sound quality control circuit, but also to a wide range of general volume/sound quality control circuits, and can easily handle changes in the gain of the subsequent audio output circuit.

The variable resistors 7 and 43 for sound quality control and the power supply for the loudness control circuit are separated from VCC1 and VCC2 by resistor 2, respectively, and oC□≦VCC2. This is to enable the voltage at the midpoint of 37°43 to be raised to the power supply voltage VCCI, and to provide flexibility in the correction characteristics by loudness control.

Also, the input terminal 26 in the volume/sound quality control circuit 25.
When the voltage applied to 27 exceeds the power supply voltage VCo0,
In the case of such two power supplies, the collector voltage of the loudness control transistors 40 and 46 must be higher than VCCI (power supply voltage) plus VF (forward voltage of diode 38 or 40) to avoid damaging the circuit. We need to make sure that this does not happen.

Therefore, the collectors of transistors 40 and 46 and the power supply VC
Connect diodes 52 and 53 between CI and
Maximize the collector voltage of transistors 40 and 46. . □
It is suppressed to +vF.

Furthermore, in this circuit, by connecting the cathodes of the diodes 52 and 53 to the switch 54 in common, the switch is turned on. It can be connected to the CI side to operate the loudness control circuit, and when it is off, it can be connected to ground to cut off the diode 38.44 and turn off the loudness control circuit, 2 circuits (low range control and treble range control) The loudness control circuits can be turned on and off simultaneously with a single switch.

Next, an example of the operating characteristics of this embodiment will be explained with reference to FIGS. 4 to 8.

FIG. 4 is a graph showing the relationship between the sound quality control voltage and the sound quality correction value in the volume/sound quality control circuit of FIG.

In addition, in FIG. 4, the sound quality control voltage refers to the input terminal 26.
The sound quality correction value indicates the degree of amplification/attenuation in the bass or treble range of the audio signal. .

The same applies to FIGS. 6 to 8, which will be described later.

As shown in FIG. 4, the volume/sound quality control circuit 2 shown in FIG.
5, when the sound quality control voltage is VCCI / 2, the sound quality correction value becomes ±OdB, and above that it becomes positive,
Sound quality control voltage is ■. When cl, the maximum value is +10 dB.

FIG. 5 is also a graph showing the relationship between the volume control voltage and the volume in the volume/tone quality control circuit of FIG. 1.

In FIG. 5, it goes without saying that the volume control voltage refers to the voltage applied to the input terminal 28.

The same applies to FIGS. 6 and 7, which will be described later.

As shown in FIG. 5, the volume/sound quality control circuit 25
1° is the maximum volume control voltage (specified maximum value)
When the volume control voltage is O, the volume is also maximum (assumed to be OdB), and when the volume control voltage is O, the volume is minimum.

It is assumed that the sound quality/volume control circuit 25 shown in FIG. 1 has the above characteristics, and that the midpoint voltage of the variable resistors 37 and 43 is V when the switch 54 is in the OFF state. If it is set to 5 so that C□/2 (set voltage), switch 5
4 is on, ie, is performing loudness control, the following operating characteristics are obtained.

A graph showing the relationship between the volume control voltage and the sound quality control voltage when the switch 54 in the sixth enlarged view of FIG. 1 is in the on state,
FIG. 7 is a graph showing the relationship between the volume control voltage and the sound quality correction value, and FIG. 8 is a graph showing the relationship between the audio frequency and the sound quality correction value when the volume control voltage is changed.

As shown in FIG. 6, when the volume control voltage is below VA, the sound quality is corrected by loudness control, and at vB, the 2 loudness control voltage (the voltage further superimposed on the set voltage by loudness control) reaches its maximum. That is, in this example, each emitter resistor 41.47 of the transistors 40, 46, each collector resistor 39.45, and the variable resistor 3 for sound quality control.
7 and 43, the above characteristics are set.

Therefore, the sound quality correction value for the clarity amount control voltage is as shown in FIG.

Further, when the correction characteristics by loudness control are expressed in terms of frequency characteristics, they become as shown in FIG. 8, and as the volume control voltage decreases from large to small, correction characteristics corresponding to the volume can be obtained from ■ to ■.

In the characteristics shown above, the middle point of variable resistor 37,430 is ■. o
This is the characteristic when the variable resistor is set at the 1/2 position, but the midpoint of the variable resistor can be set at any position, and correction characteristics can be obtained depending on the set position.

Furthermore, desired correction characteristics can be obtained by changing the correction characteristics of loudness control in the bass and treble ranges. moreover,
It is also possible to remove the circuit related to high frequency range control and correct only the low frequency range.

Next, FIG. 9 is a circuit diagram showing another embodiment of the present invention.

As shown in FIG. 9, variable resistor 37 during loudness control,
The two power supplies in FIG. 1 may be combined into one power supply (Vcc1=VCC2) depending on limitations on the midpoint voltage of 43, that is, the sound quality control voltage, and limitations on resistance values and circuit current consumption. Further, in FIG. 9, a transistor 50, which is the impedance conversion circuit in FIG. Although the resistor 49 is also omitted, there are cases where the output impedance of the volume control voltage source 51 is sufficiently low and the loudness control correction characteristic may have some temperature characteristics, or when the voltage W151 has an opposite temperature characteristic. In some cases, there is no problem in using such a circuit configuration.

Next, FIGS. 10 and 11 are circuit diagrams showing partial modifications of FIG. 1, respectively. That is, in FIGS. 10 and 11, compared to the circuit shown in FIG. 1, the circuit is designed to have a wider characteristic setting range, and only the low frequency range control side is shown as an example.

In the circuit shown in FIG. 10, variable resistor 37 and diode 3
8, the diode 38 is cut off when the loudness control is off, so the bass control voltage can be set only by the variable resistor 37, as shown in FIG. When the loudness control is on, a bass control voltage higher than the midpoint voltage of the variable resistor 37 can be applied to the input terminal 26, making it easy to set the correction characteristics of the loudness control. Furthermore, when the middle point of the variable resistor 37 is lowered to ground and the setting by the user is minimized, the bass range control voltage is limited by the ratio of the resistor 56 and the resistor 39.

In addition, the circuit line shown in FIG. 11, the variable resistor 37 shown in FIG.
This is an example in which 5 is replaced with 5 so that the midpoint voltage of is set by a resistor 57.58. In addition, the circuit lines shown in FIGS. 10 and 11 are also applied to Ic for the control of the treble range,
Also, it can be used in a case where a single power source is used as shown in FIG.

FIG. 9 is a circuit diagram showing a specific example of the switch in the 12th port enlarged in FIG. 9;

The loudness control switch shown in Fig. 9 has one diode as shown on the left in Fig. 12.

As shown in the figure on the right,
A double switch can also be used.

〔Effect of the invention〕

According to the present invention, one for each of the bass range and the treble range.
This can be achieved with a simple circuit configuration consisting of individual grounded emitter amplifier circuits and diodes that add their outputs to the sound quality control circuit, making it easy to set the operating range of loudness control and sacrificing the user's sound quality adjustment range. This has the effect of making it possible to perform loudness control according to the adjustment value with appropriate and stable correction characteristics without any noise.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, Figs. 2 and 3 are circuit diagrams showing conventional sound quality/volume control methods, respectively, and Fig. 4 is a circuit diagram showing the sound quality in the volume/sound quality control circuit of Fig. 1. A graph showing the relationship between the control voltage and the sound quality correction value, FIG. 5 is a graph showing the relationship between the volume control voltage and the volume, and the volume control voltage when the switch 54 in FIG. Figure 7 is a graph showing the relationship between the sound quality control voltage and the sound quality correction value. Figure 8 is a graph showing the relationship between the volume control voltage and the sound quality correction value. 9 is a circuit diagram showing another embodiment of the present invention, FIGS. 10 and 11 are circuit diagrams showing partial modifications of FIG. 1, and FIG. 12 is a circuit diagram showing a partial modification of FIG. FIG. 2 is a circuit diagram showing a specific example of a switch in FIG. Code explanation 17...Audio signal input terminal, 1B...
・Audio signal output terminal, 25... Volume/sound quality control circuit, 26... Bass range control voltage input terminal,
27...Treble range control voltage input terminal, 28...
...Volume control voltage input terminal, 37, 43...
・・Variable resistance, 38, 44° 52.53 ・・・・Video diode, 39, 41, 42, 45° 47.48.4
9... Resistor, 40, 46... NPN transistor, 50... PNP) U/Distor,
51... Volume control voltage source, 54... Switch agent Patent attorney Akio Namiki No. 111j1 M 2 Figure 3 Figure tA411i+ # ■ 5 Figure 6
MuT7 diagram - (111μ11 @ -1bE
-(11%su+lv Kamaishi Mi 8IIi1 11 smoke (茫- M9 figure 10 figure 11 figure 12+!!+

Claims (1)

[Claims] 1) A sound quality control circuit that controls the bass and treble ranges using a DC control voltage obtained by dividing a constant DC power supply voltage by resistance, and a sound quality control circuit that controls the bass and treble ranges using a variable DC voltage from a volume control voltage source. and a volume control circuit that controls the volume.
In the volume control method, a common emitter amplifier receiving the variable DC voltage as an input;
The sound quality of the audio equipment is characterized by providing means for superimposing the amplified output on the DC control voltage for sound quality control, and boosting the bass and treble ranges according to the volume.
Volume control method.