JPH07135436A - Variable loudness circuit - Google Patents

Abstract

PURPOSE:To attain smooth correction of an accoustic sense in a high frequency signal by connecting a 1st element and a loudness control variable resistor in the variable loudness circuit and connecting a slider contact of the control variable resistor and a 2nd element. CONSTITUTION:When the accoustic sense of a low frequency signal is corrected, since the low frequency signal hardly passes through capacitors C1, C2 and a branch is open, the gain of the low frequency signal is increased by 8dB to correct the listening sense. When the accoustic sense of a medium frequency signal is corrected, since the medium frequency signal easily passes through capacitors C2 and a resistor is closed, the gain of the medium frequency signal is suppressed within 1dB. When the accoustic sense of a high frequency signal is corrected, since the high frequency signal easily passes through capacitors C1, C2 and resistors R1, R2 are closed, the resistor R1 and the loudness control variable resistor VR1 are connected in the variable loudness circuit 3 thereby connecting the slider contact of the variable resistor VR1 and the resistor R2. Thus, the voltage division ratio obtained by the parallel resistance of the resistors Rb, R2 follows the change in the position of the variable resistor VR1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable loudness circuit, and more particularly to a audibility correction of a high frequency signal.

[0002]

2. Description of the Related Art Generally, at a low volume, human hearing ability is deteriorated for low-frequency signals and high-frequency signals rather than mid-frequency signals. This is well known as the Fletcher-Manson characteristic or Church-King characteristic.

For this reason, in an audio device, as shown in FIG. 6, a low-frequency signal and a high-frequency signal are raised relative to a mid-frequency signal so as to correct the hearing ability (this is called loudness). Is called). A variable type correction circuit for this purpose is called a variable loudness circuit.

Since this variable loudness circuit is required only when the volume is low, as shown in FIG. 10, the adjustment amount of the loudness becomes smaller as the volume becomes higher.

11 and 12 show an example of a conventional variable loudness circuit. The input signal is adjusted by the loudness operation volume control, and the auditory sense-corrected signal is output. Conventionally, such a variable loudness circuit has been used.

[0006]

However, the above conventional circuit has the following problems.

First, it is assumed that the sliding contact of the voice adjusting volume VR ₂₂ is at the midpoint for simplification of calculation. The resistor R ₂₃ is set to R ₂₃ = (1/10) · VR ₂₂ (1) in order to match the rotation angle of the sound adjusting volume VR ₂₂ with the human sense of hearing.

Further, assuming that the input voltage is vi and the output voltage is vo, the parallel resistance value of the resistors R ₁ and R ₂ ((R ₁ ·
R ₂ ) / (R ₁ + R ₂ )) is represented by R ₁ ∥R ₂ .

Further, the capacitance of the capacitor C ₂₂ is made larger than that of the capacitor C ₂₁ , and the capacitor C ₂₂ (C ₁₂ )
Indicates that the impedance becomes small for signals in the mid range and above, and the capacitor C ₂₁ has small impedance for high frequency signals.

The loudness control volume VR ₂₁
(VR ₁₁ ) has the smallest loudness effect in the state of FIG. 13a and the maximum in the state of FIG. 13b. In the following, the problems will be mentioned by classifying them into low-frequency, mid-frequency, and high-frequency signals.

1. In the case of the low frequency signal in the circuit of FIG. 11, first, in the circuit of FIG. 11, since the capacitors C ₂₁ and C ₂₂ have high impedance with respect to the low frequency signal, this branch is in an open state, and is equivalent to the circuit of FIG. Become.

[0012] input-output characteristic of this _{case, (vo / vi) Fig14 =} A / (A + VR 22/2) ··· (2) _{wherein, R A = (R 23 +} VR 21) ‖ (VR _22/2 ).

When the loudness is minimum (min) (see FIG.
3a reference), because it is VR ₂₁ = 0, (1), equation (2), the R _A = VR _22/12.

Substituting this equation into (2), (vo / vi) _Fig14min = _1/7 (3) When the loudness is maximum (max) (see Fig. 13b),
_Assuming that the maximum boost amount of the low frequency signal is 8 dB (about 2.5 times), (vo / vi) _Fig14max = 2.5 · (vo / vi) _Fig14min This equation and (1), (2), (3) According to the equation, VR ₂₁ = (21/40) · VR ₂₂ ≈ (1/2) · VR ₂₂ ... (4) According to the equations (1) and (4), VR ₂₁ = 5 · R ₂₃ ... (5 ) Therefore, in order to obtain the boost amount of the low frequency signal, VR ₂₁ >
Must be R ₂₃ .

In the case of mid-range signal Next, in the audibility correction of the mid-range signal, since C ₂₂ has a smaller impedance than the mid-range signal, R ₂₂ is in a closed state, which is equivalent to the circuit of FIG. The output characteristics of the _{case, (vo / vi) Fig15 =} B / (B + VR 22/2) ··· (6) _{wherein, R B = ((VR 21} ‖R 22) + R 23) ‖ (VR ₂₂
/ 2).

Similarly, when the loudness is the minimum (min), (vo / vi) _Fig15min = _1/7 (7) In order to lower the _midrange signal relatively, the _midrange signal when the loudness is maximum The maximum boost amount of 1 dB (about 1.125
_Times ), (vo / vi) _Fig15max = 1.125 · (vo / vi)
_Fig15min R _B = (9/94) · VR _{22 according to} this equation and equations (6) and (7) R ₂₂ = (14/732) VR ₂₂ ≈ (1 / 50) VR ₂₂ (8) R ₂₂ ≈ (1/5) R ₂₃ according to equations (1) and (8) Therefore, in order to reduce the maximum boost amount in the mid range to 1 dB, R ₂₃ > R ₂₂ And have to.

Further, according to the equation (5), R ₂₂ ≈ (1/25) VR ₂₁ (9) By this, the boost amount of the low frequency signal is increased and the boost amount of the mid frequency signal is suppressed. Becomes VR ₂₁ >> R ₂₂ .

In the case of high-frequency signal Next, in the auditory sense correction of the high-frequency signal, since C ₂₁ and C ₂₂ have a smaller impedance with respect to the high-frequency signal, both R ₂₂ and R ₂₁ are in the closed state, and the condition shown in FIG. It is equivalent to a circuit. The input / output characteristics in this case are (vo / vi) based on electric circuit theory: _Fig16 = (2C · R ₂₁ + 2C · R ₂₃ + 2R ₂₁ · R ₂₃ + C · R ₂₂ ) / (4C · R ₂₁ + 4C · R _{23 + 4R 21 · R 23 + C} · R 22 + R 21 · VR 22) ··· (10) where it is R _C = VR ₂₁ ‖R _22.

When the loudness is the minimum (min), similarly, (vo / vi) _Fig16min = _1/7 (11) The maximum boost amount of the high frequency signal at the maximum loudness is 6
_Assuming dB (about 2 times), (vo / vi) _Fig16max = 2 · (vo / vi) _Fig16min (12) R ₂₁ = by the equations (1), (4), (10) to (12) (14/167) · VR ₂₂ ≈ (1/12) · VR ₂₂ As a result, the auditory sense correction is performed for each band, and FIG.
The following characteristics can be obtained.

However, in the audibility correction of a high frequency signal,
There were the following problems.

In FIG. 16, as described above, VR ₂₁ >>
Since R ₂₂ and R _C = VR ₂₁ ‖R ₂₂ , VR ₂₁
The parallel resistance R _C does not increase due to the existence of the small resistance R ₂₂ no matter how large. For example, VR ₂₁ is 25
If KΩ and the resistance R ₂₂ are 2 KΩ, the parallel resistance R _C is 1.85 KΩ, and even if VR ₂₁ is 50 KΩ, it is 1.9.
It becomes 2KΩ and does not change much. Therefore, the boost amount with respect to the change of VR _{21 has} the characteristic shown in FIG. That is, in the audibility correction of the high frequency signal, since the gradient of the volume adjustment is steep, the VR ₂₁ reaches the maximum boost amount with a small value, and smooth adjustment is difficult and unnatural correction occurs. there were.

2. In the case of a low-frequency signal in the circuit of FIG. 12, since this low-frequency signal does not easily pass through the capacitor C ₁₂ , this branch is in an open state, which is equivalent to the circuit of FIG. Further, in the middle and high frequency signals, the capacitor C ₁₂ is easily passed and is short-circuited in this branch, which is equivalent to the state of the circuit in FIG.
R ₁₁ cannot be adjusted. This state is shown in FIG. That is, the circuit of FIG. 12 also has a problem that it is difficult to correct the audibility of high frequency signals.

An object of the present invention is to solve the above problems and provide a variable loudness circuit capable of smooth audible correction of high frequency signals.

[0024]

The variable loudness circuit according to claim 1 is provided between a first input end, a second input end, and between the first input end and the second input end, and the audibility correction is performed. A loudness operating volume for performing the first, which is provided between the first input end and the loudness operating volume, and which changes impedance according to frequency to pass only high frequency signals.
Element, sliding contact of loudness control volume and second
Is provided between the first input terminal and the second input terminal, which is provided between the first input terminal and the second element, which is provided between the second input element and A volume adjusting volume to be adjusted, a third element provided between the sliding contact of the loudness operating volume and the center tap of the volume adjusting volume, and a first element connected to the sliding contact of the volume adjusting volume. An output end and a second output end connected to the second input end are provided.

A variable loudness circuit according to a second aspect of the present invention is provided with a first input end, a second input end, and between the first input end and the second input end, and the loudness control knob for correcting the audibility is provided. A first capacitor provided between the first input end and the loudness control knob for passing only a high-frequency signal and a first resistor, a sliding contact of the loudness control knob, and a second input end. A second resistor provided between the second resistor and a second capacitor that passes only signals in the midrange or higher, and a volume adjuster that is provided between the first input end and the second input end to adjust the volume. A volume, a third resistor provided between the sliding contact of the loudness operating volume and the center tap of the volume adjusting volume, a first output end connected to the sliding contact of the volume adjusting volume,
And a second output end connected to the second input end.

[0026]

In the variable loudness circuit according to the first aspect of the present invention, the first element and the loudness operating volume are connected at the time of a high frequency signal, and the sliding contact of the loudness operating volume is connected to the second element. I am trying. Therefore, since the voltage is divided into the series resistance of the first element and the loudness control volume and the parallel resistance of the second element and the loudness control volume, the change of the loudness control volume in the auditory correction of the high frequency signal. The gradient of the change in the boost amount with respect to can be made gentle.

In the variable loudness circuit according to a second aspect of the present invention, the first resistance and the loudness operating volume are connected when a high frequency signal is supplied, and the sliding contact of the loudness operating volume is connected to the second resistance. I am trying. Therefore, the voltage is divided into the first resistance and the series resistance of the loudness control volume and the parallel resistance of the second resistance and the loudness control volume, so that the loudness control volume change in the auditory correction of the high frequency signal. The gradient of the change in the boost amount with respect to can be made gentle.

[0028]

1 shows a variable loudness circuit 3 according to an embodiment of the present invention. This circuit 3 has a first input terminal IN
₁ , second input terminal IN ₂ , loudness control volume V
R1, the center tapped volume control volume VR _2, the first capacitor C ₁ and the first resistor R _1, the second capacitor C ₂ and the second resistor R _2, a third resistor R _3, the first It has an output terminal OUT ₁ and a second output terminal OUT ₂ .

The first input terminal IN _1, the between the second input terminal IN ₂ first capacitor C ₁ and the first resistor R _1, and the loudness operating volume VR _1, further performing audibility correction provided There is.

Further, between the first input terminal IN ₁ and the second input terminal IN ₂ , a volume adjusting volume V for adjusting the volume is provided.
R ₂ is provided.

A second capacitor C ₂ and a second resistor R ₂ are provided between the sliding contact of the loudness operating volume VR ₁ and the second input end IN ₂ . Further, a third resistor R ₃ is provided between the sliding contact of the loudness operating volume VR ₁ and the center tap of the volume adjusting volume VR ₂ .

The first output terminal OUT ₁ is connected to the sliding contact of the volume adjusting volume VR ₂ . Also, the second
The second output terminal OUT ₂ is connected to the input terminal IN ₂ .

The operation of the variable loudness circuit 3 will be described below with reference to FIGS.

First, in the case of the audibility correction of the low frequency signal, in the circuit of FIG. 1, since the low frequency signal is difficult to pass through the capacitors C ₁ and C ₂ , this branch is in an open state, which is equivalent to the circuit of FIG. . Since this circuit is the same as the circuit shown in FIG. 14, the gain of the low frequency signal is increased by 8 dB, and the audibility correction is performed in the same manner as in the conventional case.

Next, in the case of the audibility correction of the mid-range signal, in the circuit of FIG. 1, since the mid-range signal easily passes through the capacitor C ₂ , the resistor R ₂ is closed and becomes equivalent to the circuit of FIG. . Since this circuit is the same as the circuit of FIG. 15, the gain of the mid-range signal can be suppressed within 1 dB.

In the audibility correction of the high frequency signal, the high frequency signal easily passes through the capacitors C ₁ and C ₂ , so that the resistor R ₂ and R ₁ are in a closed state, which is equivalent to the circuit of FIG. Here, the upper resistance value of the loudness operation volume VR ₁ is Ra, and the lower resistance value thereof is Rb.

The input-output characteristic in this case is based on the electrical circuit _{theory, (vo / vi) Fig4 =} (2D · (R 1 + Ra) + 2D · R 3 +2 (R 1 + Ra) · R 3 + D · R 2 ) / (4D · (R ₁ + Ra) + 4D · R ₃ +4 (R ₁ + Ra) · R ₃ + D · R ₂ + (R ₁ + Ra) · VR ₂ ) ... (13) where D = Rb‖ When R ₂ loudness is minimum (see FIG. 5a), R
Since b = 0, according to the equations (1) and (13), (vo / vi) _Fig4min = _1/7 (14) When the loudness is maximum (max) (see FIG. 5b), R
Since a = 0, according to the equations (10) and (13), (vo / vi) _Fig4max = (vo / vi) _Fig16max (15) Therefore, the variable loudness circuit 3 is the circuit diagram of FIG. The same audibility correction can be performed.

As a result, the audibility correction is performed for each band, and the audibility correction as shown in FIG. 6 is performed.

However, the variable loudness circuit 3 is significantly different from the conventional circuit.

[0040] In this variable loudness circuit 3, when the high-frequency signal, the resistor R ₁ and to connect the loudness operating volume VR _1, for connecting the sliding contact of the loudness operating volume VR ₁ and resistor R ₂ I am trying.

Therefore, the loudness control volume VR
_In the sliding contact ₁ , the series resistance of the resistance R ₁ and the resistance Ra on the upper side of the loudness control knob VR ₁ and the resistance R ₂
And the lower resistance Rb of the loudness control knob VR ₁
And parallel resistance with. That is, the conventional (1
The resistance corresponding to the resistance R ₂₁ in the expression (0) is (R ₁ + Ra) in the expression (13). Therefore, the partial pressure ratio of the parallel resistance value and D of the resistor Rb and R ₂ and (R ₁ + Ra) is to follow smoothly to changes in loudness operating volume VR _1. FIG. 7 shows the relationship between changes in the loudness operation volume and changes in the boost amount.

Thus, in the audibility correction of the high frequency signal,
The gradient of the change in the boost amount with respect to the change in the loudness operation volume VR ₁ can be made gentle as compared with the conventional FIG. As a result, it becomes possible to perform a smooth audible correction not only for the low frequency signal but also for the high frequency signal.

In this embodiment, the capacitor and the resistor are used as the element that changes the impedance depending on the frequency, but a coil and a resistor may be used.

[0044]

According to the variable loudness circuit of the first aspect, the first element and the loudness operating volume are connected to each other at the time of a high frequency signal, and the sliding contact of the loudness operating volume is connected to the second element. I am trying to do it. Therefore, the first
Since the voltage is divided into the series resistance of the element and the loudness operation volume and the parallel resistance of the second element and the loudness operation volume, the boost amount of the boost amount with respect to the change of the loudness operation volume in the auditory compensation of the high frequency signal is divided. The slope of change can be moderate.

As a result, it is possible to provide a variable loudness circuit capable of smooth audible correction of high frequency signals.

According to a second aspect of the variable loudness circuit, the first resistance and the loudness operating volume are connected to each other when a high frequency signal is supplied, and the sliding contact of the loudness operating volume is connected to the second resistance. I have to. Therefore, the series resistance of the first resistance and the loudness control volume, and
Since it is divided into the second resistance and the parallel resistance of the loudness control knob, in the audibility correction of the high frequency signal,
The slope of the change in the boost amount with respect to the change in the loudness operation volume can be made gentle.

[Brief description of drawings]

FIG. 1 is a diagram showing a variable loudness circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a variable loudness circuit for a low frequency signal.

FIG. 3 is a diagram showing a variable loudness circuit for a mid-range signal.

FIG. 4 is a diagram showing a variable loudness circuit for a high frequency signal.

FIG. 5 is a diagram showing adjustment of a loudness operation volume.

FIG. 6 is a diagram showing a characteristic curve of audibility correction.

FIG. 7 is a diagram showing a relationship between changes in loudness operation volume and changes in boost amount.

FIG. 8 is a diagram showing a state of loudness with respect to a change in volume.

FIG. 9 is a diagram showing a conventional variable loudness circuit.

FIG. 10 is a diagram showing a conventional variable loudness circuit.

FIG. 11 is a diagram showing adjustment of a loudness operation volume.

FIG. 12 is a diagram showing a conventional variable loudness circuit for a low frequency signal.

FIG. 13 is a diagram showing a variable loudness circuit for a conventional mid-range signal.

FIG. 14 is a diagram showing a conventional variable loudness circuit for a high frequency signal.

FIG. 15 is a diagram showing a characteristic curve of conventional audibility correction.

FIG. 16 is a diagram showing a relationship between a change in a conventional loudness operation volume and a change in a boost amount.

FIG. 17 is a diagram showing a conventional variable loudness circuit for a low frequency signal.

FIG. 18 is a diagram showing a variable loudness circuit for a conventional mid-high range signal.

FIG. 19 is a diagram showing a characteristic curve of a conventional auditory sense correction.

[Explanation of Codes] IN ₁ ... First input end IN ₂ ... Second input end VR ₁ ... Loudness control volume (upper Ra,
Lower side Rb) VR ₂ ... Volume adjusting volume C ₁ ... First capacitor R ₁ ... First resistor C ₂ ... Second capacitor R ₂ ... Second resistor R ₃ ... 3rd resistance OUT ₁ ... 1st output end OUT ₂ ... 2nd output end

Claims (2)

[Claims] 1. A first input end, a second input end, a loudness operation volume provided between the first input end and the second input end for performing auditory sense correction, and a first input end. A first element that is provided between the loudness operating volume and changes impedance depending on the frequency to pass only a high frequency signal, and is provided between a sliding contact of the loudness operating volume and a second input end. , A second element that changes impedance according to frequency to pass signals in the mid-range or higher, a volume adjusting volume provided between the first input end and the second input end to adjust the volume, and a loudness operation The third element provided between the sliding contact of the volume control knob and the center tap of the volume control knob, the first output terminal and the second input terminal connected to the sliding contact of the volume control knob, respectively. Contact Variable loudness circuit comprising the second output terminal, that is. 2. A first input end, a second input end, a loudness operating volume provided between the first input end and the second input end for performing auditory sense correction, and a first input end. A first resistor provided between the loudness control knob and a first capacitor for passing only a high frequency signal, a first capacitor provided between the sliding contact of the loudness control knob and the second input end. 2 resistance and a second capacitor that passes only signals in the mid range or higher, a volume adjusting volume that is provided between the first input terminal and the second input terminal and adjusts the volume, and a loudness operating volume. A third resistor provided between the sliding contact and the center tap of the volume adjusting volume, a first output end connected to the sliding contact of the volume adjusting volume, and a second input end connected to the second input end. With a second output end, Variable loudness circuit, characterized in that.