JPH062338Y2 - Loudness circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a loudness circuit mainly used for an audio circuit.

[Prior art]

As is well known, in the human ear, it becomes difficult to hear both low and high frequencies as the sound pressure decreases. The Fletcher-Manson isoloudness curve illustrates this property well. Therefore, in the audio circuit, a loudness circuit is used which corrects the sound volume in the low range and the high range in response to the decrease in the sound volume and flattens the audible characteristics.

[Problems to be solved by the invention]

By the way, the conventionally known loudness circuit can perform appropriate auditory sense correction when the input signal is attenuated up to about 20 dB. However, when the input signal S is attenuated to a maximum of −40 dB, especially 0 to −2
There is a problem that proper audibility correction cannot be performed in the 0 dB attenuation range.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a loudness circuit capable of performing good auditory sense correction over the entire attenuation range of 0 to -40 dB.

[Means for solving problems]

In order to solve the above problems, in the present invention, a high frequency boost circuit inserted between an input terminal to which an input signal is applied and an output terminal to which an output signal is output, and one end of which is connected to the input terminal. A variable resistor having a single intermediate tap, the slider being connected to the output terminal, and a first low-pass boost circuit interposed between the intermediate tap and a ground end, A second low-frequency boost circuit interposed between the other end of the variable resistor and the grounded end, and the resistance value from the one end to the other end of the variable resistor is the variable resistor. In the state where the slider of the variable resistor is located between the one end and the intermediate tap and the amount of attenuation of the output signal with respect to the input signal is small, the variable resistor causes the large resistance component between the intermediate tap and the other end to To reduce the effect of the second low range boost circuit As a result, the predetermined low-frequency boost characteristic corresponding to the equal loudness curve in the state where the attenuation amount is small has a variable resistor portion from the one end to the intermediate tap of the variable resistor and the first low-frequency boost circuit. When the slider of the variable resistor is located between the intermediate tap and the other end and the amount of attenuation of the output signal with respect to the input signal is large, the amount of attenuation is A predetermined low-pass boost characteristic corresponding to the equal loudness curve in a large value adjusts the variable resistor portion from the intermediate tap to the other end of the variable resistor and the second low-pass boost circuit. The maximum attenuation of the output signal with respect to the input signal is large, and the low-range boot that almost matches the equal loudness curve over the entire attenuation range is set. It is characterized in that to obtain a preparative amount.

[Action]

In the present invention, the resistance value from one end to the other end of the variable resistor is such that the slider of the variable resistor is located between the one end and the intermediate tap and the attenuation amount of the output signal with respect to the input signal is small. Then, by reducing the influence of the second low-frequency boost circuit by the large resistance component between the center tap and the other end of the variable resistor, a predetermined low value corresponding to the equal loudness curve in the state where the attenuation amount is small is obtained. The region boost characteristic is a resistance value that can be defined by the variable resistor portion from one end to the intermediate tap of the variable resistor and the first low-frequency boost circuit, and the slider of the variable resistor is from the intermediate tap. When the attenuation amount of the output signal with respect to the input signal is large, which is located between the other ends, the predetermined low-frequency boost characteristic corresponding to the equal loudness curve in the state where the attenuation amount is large is that of the variable resistor. It is set to a resistance value from the intermediate tap Chi can be defined by adjusting the variable resistor portion and the second bass boost circuit to the other end.

As a result, the mutual influence of the first and second low-frequency boost circuits becomes small, and the low-frequency boost characteristics corresponding to the equal loudness curve of the attenuation amount with respect to the attenuation amount corresponding to each low-frequency boost circuit. Can be given.

Therefore, for example, if the total attenuation range is set to 0 to -40 dB and the position of the intermediate tap is set to a position corresponding to -20 dB, a good low range is obtained by the first low range boost circuit in the range of 0 to -20 dB attenuation. In the attenuation range of -20 dB to -40 dB, the second low-frequency boost circuit obtains a good low-frequency boost characteristic, which is good in the entire attenuation range of 0 to -40 dB. It is possible to perform various audible corrections.

〔Example〕

First, before describing an embodiment of the present invention, a loudness circuit which is a premise of the present invention will be described with reference to FIG. In this figure, reference numeral 1 is an input terminal to which an audio input signal S is applied, 2 is an output terminal, and 3 is a variable resistor for adjusting the volume. Further, the series circuit of the resistor 4 and the capacitor 5 serves as a high-frequency boost circuit that raises the level of the high frequency component of the input signal S, and the series circuit of the resistor 6 and the capacitor 7 raises the level of the low frequency component of the input signal S. Each low-frequency boost circuit is configured. Then, the input signal S is attenuated according to the position of the slider of the variable resistor 3, and high-frequency boost and low-frequency boost are performed and output from the output terminal 2.

FIG. 8 shows the values of the resistors 4 and 6, the variable resistor 3 and the capacitors 5 and 7 in the circuit of FIG.
It is a figure which shows the frequency characteristic of an output signal at the time of making Ω, 100 kΩ, 680 pF, 0.22 μF, and capable of attenuating the input signal S up to -40 dB, and in this figure, a curve L1 shows sliding of the variable resistor 3. When the child is near the terminal 3a, the curve L5 is when the slider is at the position of the terminal 3b. As shown in this figure, the circuit of FIG.
In the range of -20 dB to -40 dB attenuation, good boost characteristics can be obtained in both the low range and the high range.
In the -20 dB attenuation range, the low-frequency boost is not particularly sufficient, and therefore proper hearing correction cannot be performed.
That is, it can be seen that the loudness circuit shown in FIG. 7 has the same problem as the conventional loudness circuit.

Next, a loudness circuit according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of a loudness circuit according to an embodiment of the present invention. In this figure, reference numeral 11 is an input terminal to which an input signal S is applied, 12 is an output terminal, and a resistor 1 is provided between these input terminal 11 and output terminal 12.
3, a high frequency boost circuit 15 including a capacitor 14 is inserted. Reference numeral 16 is a variable resistor for adjusting the volume having an intermediate tap 16c, and its terminal 16a is the input terminal 1
1 and the slider 16d is connected to the output terminal 12 via the resistor 17. Further, a first low-frequency boost circuit 2 in which a resistor 18 and a capacitor 19 are connected in series between the intermediate tap 16c of the variable resistor 16 and the ground.
0 is inserted, and a resistor 21 and a capacitor 22 are connected in series between the terminal 16b of the variable resistor 16 and the ground.
The low-frequency boost circuit 23 is inserted.

In the above configuration, the high frequency boost is performed by the high frequency boost circuit 15 as in the circuit shown in FIG. On the other hand, the low-frequency boost includes the first and second low-frequency boost circuits 2
0,23. That is, first 0 to -20
In the attenuation range of dB, the first low-frequency boost circuit 20
The level of the low frequency component of the input signal S rises above the level of the middle frequency component based on the CR characteristic of. In this case, since the resistance between the slider 16d of the variable resistor 16 and the terminal 16b is large, the influence of the second low-frequency boost circuit 23 is small. Next, in the attenuation range of -20 dB to -40 dB, the resistance between the slider 16d and the terminal 16b of the variable resistor 16 becomes small, and as a result, the CR characteristic of the second low-frequency boost circuit 23 is mainly increased. Based low range boost is performed. The resistor 17 is inserted to reduce the amount of attenuation in the high frequency region near the maximum attenuation (-40 dB). Then, the high frequency change characteristic is first adjusted in the attenuation range of 0 to -20 dB by adjusting the resistor 13 of the high frequency boost circuit 15 so as to obtain an appropriate high frequency attenuation amount in this range, and then set to -20 to 20. As the attenuation range of −40 dB, the resistor 17 may be adjusted here, and further, it may be set so that an appropriate high frequency attenuation amount can be obtained even in this range. In addition,
Here, the resistors 13 and 17 can be adjusted substantially independently of each other.

FIG. 2 shows a variable resistor 16, a resistor 13,
The values of 17, 18, 21 and capacitors 14, 19, 22 are respectively 200KΩ, 27KΩ, 470Ω, 8.2Ω, 5
It is a figure which shows the frequency characteristic of an output signal at 60 Ω, 680 PF, 0.015 μF, and 0.22 μF. In this figure, a curve K1 is a curve when the slider 16d of the variable resistor 16 is near the terminal 16a. K2 to K4 are when the slider 16d is located between the terminals 16a and 16b, and curve K5 is when the slider 16d is located at the terminal 16b. As is clear from comparing FIG. 2 and FIG. 8, according to the circuit of FIG.
Even in the dB attenuation range, a sufficient low range boost characteristic can be obtained.

[Other Embodiment (1)] FIG. 3 shows another embodiment of the present invention. In FIG. 3, the same parts as those in FIG. 1 are designated by the same reference numerals. In this circuit, the insertion position of the high frequency boost circuit 15 in FIG. 1 is changed so that it is connected between the terminal 16a of the variable resistor 16 and the intermediate tap 16c. Also by this, almost the same effect as that of the embodiment shown in FIG. 1 can be obtained.

[Other Embodiment (2)] FIG. 4 shows still another embodiment. In FIG. 4 as well, parts common to those in FIG. 1 are designated by the same reference numerals.
In this circuit, the variable resistor 16 shown in FIG. 1 is replaced with a variable resistor 16 'having a special structure. The variable resistor 16 'has substantially two internal resistors, and when the slider 16d slides from the terminal 16a to the terminal 16b through the intermediate tap 16c, the terminal Between 16a and the intermediate tap 16c, the slider 16d slides on the first resistor r1 connected between the terminal 16a and the intermediate tap 16c, and between the intermediate tap 16c and the terminal 16b. The slider 16d slides on a second resistor r2 having one end connected to the terminal 16b and the other end connected to a position corresponding to the intermediate tap 16c, and the intermediate tap of the first resistor r1. It is configured to come into contact with a conductor c that extends from the side of 16c to a position corresponding to the terminal 16b. In the case of such a configuration, although the variable resistor 16 'itself is a little complicated and the cost is increased, the resistances r1 and r2 are made independent from each other so that the attenuation range is 0 to -20 dB and -20 to -40 dB. Circuit mutual interference can be eliminated, and each resistor r
Since the characteristics of 1 and r2 can be individually optimized and set, the loudness change characteristics can be made closer to an ideal shape.

As shown in FIG. 5 or FIG. 6, a loudness circuit having characteristics equivalent to those of the circuit in FIG. 1 can be configured by using two variable resistors 25 in series. However, in the case of these circuits, since two variable resistors 25 are required in series, the cost and space efficiency are deteriorated as compared with the circuit in FIG.

[Effect of device]

As described above, according to this invention, the variable resistor with the intermediate tap is used as the variable resistor for adjusting the volume, and the first low-frequency boost circuit is inserted between the intermediate tap of this variable resistor and the ground. Since the second low-frequency boost circuit is inserted between the other end of the variable resistor and the ground, it is possible to obtain the effect that good auditory sense correction can be performed over the entire attenuation range of 0 to -40 dB.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a loudness circuit according to an embodiment of the present invention, FIG. 2 is a diagram showing a frequency characteristic of an output signal of the loudness circuit, and FIG. 3 is a configuration of another embodiment of the present invention. FIG. 4 is a diagram showing a configuration of still another embodiment of the present invention, FIGS. 5 and 6 are circuit diagrams showing other configuration examples of the loudness circuit, and FIG. 7 is a conventional loudness. FIG. 8 is a circuit diagram showing a circuit configuration, and FIG. 8 is a diagram showing frequency characteristics of an output signal of the loudness circuit shown in FIG. 11 ... Input terminal, 12 ... Output terminal, 15 ... High frequency boost circuit, 16, 16 '... Variable resistor, 16c ...
Middle tap, 16d ... Slider, 17 ... Resistance, 20 ...
... first low-frequency boost circuit, 23 ... second low-frequency boost circuit.

Claims (1)

[Scope of utility model registration request] 1. A high-frequency boost circuit interposed between an input terminal to which an input signal is applied and an output terminal from which an output signal is output, and one end of which is connected to the input terminal and which is connected to the output terminal. A variable resistor having a single center tap, to which the slider is connected, a first low-frequency boost circuit interposed between the center tap and a ground end, and the other end of the variable resistor. And a second low-frequency boost circuit interposed between the variable resistor and the ground end, and the resistance value from the one end to the other end of the variable resistor is a slider of the variable resistor. When the attenuation amount of the output signal with respect to the input signal is small between the one end and the intermediate tap, the second low-frequency boost is generated by the large resistance component between the intermediate tap and the other end of the variable resistor. By reducing the effect of the circuit, the amount of attenuation A predetermined low frequency boost characteristic corresponding to the equal loudness curve in a small state has a resistance value that can be defined by the variable resistor portion from the one end to the intermediate tap of the variable resistor and the first low frequency boost circuit. In the state where the slider of the variable resistor is located between the intermediate tap and the other end and the attenuation amount of the output signal with respect to the input signal is large, the equal loudness curve in the state where the attenuation amount is large is present. Is set to a resistance value that can be specified by adjusting the variable resistor portion from the intermediate tap to the other end of the variable resistor and the second low frequency boost circuit. Therefore, the maximum amount of attenuation of the output signal with respect to the input signal is large, and a low-frequency boost amount that approximately matches the equal loudness curve is obtained over the entire attenuation range. Loudness circuit according to claim.