JPS6342512A - Tone control circuit - Google Patents

Abstract

PURPOSE:To reduce the number of switches to simplify the constitution by making it possible to connect a capacitor or the like between a sound signal source and a variable resistance or between two variable resistances. CONSTITUTION:The sound signal from a sound signal source 34 passes a high band stop filter 8 from a line 7 and is given to an integrated circuit 9. The integrated circuit 9 is provided with a low band boosting circuit 10. This circuit 10 includes a capacitor C2. The third switch S3 is interposed between a terminal 12 as one end of the first resistances R11-R1k and a connection point 16 near the middle position of the second resistances R21-R2l. A switch control circuit 17 is operated by the control signal which is given through a terminal 19 from a processing circuit 18 consisting of a microcomputer or the like and selectively closes/opens the first switches S11-S1(k+1), the second switches S21-S2(l+1), and the third switch S3.

Description

Detailed Description of the Invention Technical Field The present invention relates to a sound quality and ii1!1 circuit, and more specifically to a sound quality adjustment circuit that can be suitably implemented in an electronic volume integrated circuit with a built-in so-called tone control circuit. .

Background technology The basic configuration of the high frequency cutoff circuit is shown in FIG.

The resistor R41 to which the acoustic signal from the acoustic signal source 1 is applied via the line 2, the capacitor C41, and the resistor R42 of the variable resistor 1 for adjusting sound quality play the role of cutting off high frequencies and are variable. By moving the connecting end 3 of resistor 1 to the upper side of FIG. 7, the high frequency range is greatly reduced. This circuit further includes a resistor R43, a capacitor C42, and an audio variable resistor WV2.

FIG. 8 shows the basic configuration of the loudness circuit.

A relative treble adjustment circuit, etc., indicated by reference numeral 4, is arranged upstream of this loudness circuit. This loudness circuit includes a resistor R51, a capacitor fc51, a switch S51, S52, a resistor R52, and a capacitor C52.
and a sound j1.1 adjustment variable resistor v2 are provided. When the loudness operation for enhancing the low and high frequencies at low volume is not performed, the switch S51 is cut off and the switch S52 is kept conductive. When the loudness operation is performed, the switch SSI is made conductive and the switch s52 is cut off. As a result, at low fffi when the connecting end 5 of the variable resistor (2) is located at the lower side in FIG. 8, the low and high frequencies are enhanced.

When trying to realize the high-frequency cutoff circuit shown in FIG. 7 and the loudness circuit shown in FIG. 8 using a common integrated circuit, the circuit shown in FIG. 9 can simply be considered. Dew. In FIG. 9, resistor R61 and capacitor C61 correspond to resistor R41 and capacitor C41 in FIG. 7, and similarly, in FIG. 8, resistor I? 5
1 and capacitor C51. capacitor C62
corresponds to capacitor C42 in FIG. 7, and similarly corresponds to capacitor C52 in FIG. Resistor R11
~R1n and switch Sll~S1 (n+1) have sound quality i11! Corresponds to i variable resistor ■1. Resistance R
21 to R2+e and switches 321 to S2 (logic+1) correspond to variable resistor 2 for volume 31g.

When performing the same operation as the high frequency cutoff circuit shown in FIG. 7, the switch S61 is turned on, and the switch S62
and 83 are cut off, and one of Sll-5l(n+1) is made conductive to adjust the sound quality. To achieve a function similar to the loudness circuit shown in FIG.
GI is cut off, switch S11 is turned on, and S12 to S
1 (n+1) or switch Sll~
5l(n+1) and when no loudness operation is performed, the switch S62 is turned on and the switch S62 is turned on.
Block 3. When performing the loudness operation, the switch SG2 is cut off and the switch S3 is made conductive.

Problems to be Solved by the Invention In the configuration shown in FIG. 9, the number of switches increases, and when such a configuration is realized by an integrated circuit, by making each switch an analog switch, The switch occupies a large area on the semiconductor chip, making it impossible to reduce the cost.

In addition, when high-frequency cutoff operation is performed, the resistance when the analog switch is turned on is large, for example, several hundred Ω (therefore, the performance is severely degraded. In particular, the switch S
Among ll to Sl (mouth+1), when the switch closer to switch Sll is turned on, the change in characteristics is most noticeable when the attenuation in the high frequency range is small.The conductive switch 161 is connected in series with the switches Sit to Sin. In general, in high-frequency cutoff circuits, where the negative effect is large when these analog switches conduct, the resistance value near both ends of resistors R11 to R10 is set low, and therefore, the resistance value when the analog switch conducts is set low. The degree of change in characteristics increases.

The configuration shown in FIG. 9 is for one channel, and in the case of stereo reproduction, etc., the configuration shown in FIG. 9 is provided for both channels, and the above-mentioned problem occurs in each channel.

An object of the present invention is to provide a sound quality adjustment circuit that can simplify the configuration by reducing the number of switches and improve characteristics.

Means for resolving the points between the two resistors The present invention provides a plurality of hc@1 resistors connected in series, and a plurality of hc@1 resistors connected in series, and a plurality of A variable resistance circuit for adjusting sound quality having one switch, a plurality of second resistors connected in series, and one end connected to the connection point of the second resistors! A variable resistance circuit for sound quality adjustment having a plurality of second switches whose @ ends are commonly connected; an m3 switch interposed between one end of the ml resistor and near the intermediate position of the second resistor; and an fjS1 resistor. a third resistor interposed between the other end and the vicinity of the intermediate position of the second resistor, and a circuit that selectively controls conduction/cutoff of the ml~third switch, A capacitor or the like can be connected between one end of the first resistor and the other end of the second resistor, and the common connection point of the first switch is connected to the other end of the second resistor. This is a sound quality adjustment circuit characterized in that it is connected.

According to the present invention, during high frequency cutoff and loudness operation, a capacitor is connected between the acoustic signal source and one end of the f:tS1 resistor, and a capacitor is connected between the other end of the first resistor and the second resistor. Connect a capacitor between the other end.

During the high frequency cutoff operation, the third switch is cut off, any one of the first switches is made conductive, and the remaining first switches are cut off to adjust the sound quality.

2. When not performing the loudness operation, the third switch is cut off. When performing the loudness operation, all the first switches are cut off while the third switch is conductive, or the middle f of the first switch is turned off. Establish conduction through one installed near the device.

For ffff1 adjustment, one of the tjS2 switches is turned on and the rest of the second switches are turned off.

Further, according to the present invention, by blocking the acoustic signal source and -i of the first resistor and blocking the third switch, any one of the first switches is selectively made conductive. This allows low-frequency boost operation to be performed.

Furthermore, according to the present invention, the other end of the first resistor and the other end of the second resistor remain electrically connected, or one of the first switches on the other end side of the first resistor remains electrically conductive, In this state, when the third switch is turned off, one of the first switches can be selectively turned on to cut off the high frequency range.

Embodiment FIG. 1 is an electrical circuit diagram of an embodiment of the present invention. Acoustic signal! The acoustic signal from 234 is applied to integrated circuit 9 via line 7 and high-frequency cutoff filter 8 . The high-frequency cutoff filter 8 includes a resistor R1 and a capacitor C1. Associated with the integrated circuit 9 is a low frequency boost circuit 10 . This low frequency boost circuit 10 includes a capacitor C
Contains 2.

The sound quality adjustment variable resistance circuit 11 includes a plurality of ml resistors R11 to R1k connected in series, and a first resistor R of C2.
A plurality of (k+1) first switches Sll~ whose one end is connected to the connection point of 11~R1k and whose other ends are commonly connected
5l(k+1). One end of the first resistor is terminal 12
and the other end? Connected to child a 13.

¥! The first adjustment variable resistance circuit V114 includes a plurality of second resistances R21 to R2J? connected in series. And those second resistors R21 to R2J? A plurality of second switches 321 to S2 (
, /+1). fjS2 resistance R21~R2,i
One end of F is connected to terminal 6, and the other end is connected to terminal 15.

The m3 switch S3 is interposed between a terminal 12, which is one end of the first resistors R11 to R1k, and a connection point 16 near an intermediate position between the second resistors R21 to R2. The third resistor R3 is
It is interposed between the terminal 13, which is the other end of the first resistors R11 to R1k, and the connection point 1G. Resistor R2j among the second resistors R21 to R27 is 1/2 of the numerical value l or an integer around 1/2 thereof.

The switch control circuit 17 operates in response to a control signal that connects the terminal 19 from a processing circuit 18 implemented by a microcomputer or the like, and operates the first switch Sll to 5t (
k+1), second switch 321 to S2 (, iF+1),
and selectively conducts/cuts the third switch S3,
These switches are realized by analog switches.

The first resistors R11 to R1k are determined, for example, as shown in table m1, where k=12, and the total resistance in series of these first resistors R11 to R1k is 10Ω.

(Margin below) Chapter 1 Table The third resistor R3 is IKΩ.

In order to cause the integrated circuit 9 to perform the same operation as the high-frequency cutoff circuit shown in FIG.
The resistance R1 is set to 3.3Ω, and the capacitor C1
is set to 0.1 μF, and the capacitor C2 in the low-frequency boost circuit 10 is set to 1.0 μF. :jS3 Switch S3 remains cut off. At this time, the first switch S
One of ll~S 1 (k+1) can be made conductive and the rest blocked, thereby adjusting the sound quality.

The Pt52 diagram is a graph showing the characteristics of the high-frequency cut-off motion 11= shown in FIG. 1 for Ji switches Sll to S1 (
When the switch closer to switch S11 among the switches (k+1) is made conductive and the remaining ones are cut off, a characteristic indicated by reference numeral 20 is obtained. By changing the conductive switch from switch Sll to the upper part of FIG. 1, a characteristic 21 in which the low frequency range is raised can be obtained. Such characteristics can be obtained by selectively conducting one of the switches 811 to Sli up to the vicinity of the first switch Sli corresponding to the resistor R1i located approximately in the middle of the first resistors R11 to R1k. It will be done. The numerical value i is 1/2 of k or an integer close to it. mi switch 811-51 (k+
1) Connect the conductive switch to the switch S near the middle position.
By also moving li yoi) upwards in Figure 1,
As shown by characteristic 22 in FIG. 2, a characteristic is obtained in which the low frequency range is further lifted and the high frequency range is attenuated.

In order to enable the integrated circuit 9 to perform the loudness operation corresponding to the above-mentioned FIG. do.

The capacitor C1 is set to 0.0022 to 0.01 μF. The capacitor C2 in the low frequency boost circuit 10 is
Set at 0.22 to 0.33 μF. When the loudness operation is not performed, the third switch S3 is kept shut off.

The lowest switch S11 of the Pt51 switches 811 to 51 (k+1) is made conductive, and the remaining switch 812
~S 1 (k+1) is cut off, switch S1
1 may be made conductive, and instead of making the switch Sll conductive, a switch near it, for example S12
The series resistance of the first resistors R11 to R1k, which may be electrically conductive, is, for example, about 10Ω as described above, and there is little adverse effect on the first resistors R11 to R1 when the loudness is not activated.

When performing the loudness circuit, the third switch S3 is turned on. All of the first switches Sll to S 1 (k+1) are cut off, or instead of this, the first switch Sll
~31 (k+1) The switch near the intermediate position, for example Sli, may be made conductive and the remaining first switch may be turned off. When the integrated circuit 9 is used as a loudness circuit, the sound 1 signal source 34 and the terminal 14 may be turned on. There is a bus between
A treble adjustment circuit may also be provided.

Note that the volume can be adjusted by turning on one of the switches 321 to 52()+1) and cutting off the remaining ones. The acoustic signal No. 13 is sent from the terminal 35 to the amplifier circuit 23, and is connected to the speaker 2.
4 is driven.

FIG. 3 is an electrical circuit diagram of another embodiment of the invention. This embodiment is similar to the previous embodiment and corresponding parts are provided with the same reference numerals. In this embodiment, the terminal 6 of the integrated circuit 9 is connected via a line 7 to an acoustic echo signal source 34. Directly from? An IF7 signal is provided.

Terminal 12 is left open. The third switch S3 remains shut off. According to this embodiment, by selectively turning on one of the first switches Sll to S 1 (k+1) in this order, the characteristics 25, 2 f3, 27 shown in FIG. obtained in order, the low range is enhanced and a low range boost is performed.

FIG. 5 is an electrical circuit diagram of another embodiment of the invention. This embodiment is also similar to the previous embodiment, but it should be noted that terminals 13.15 are connected by line 28. The third switch S3 remains closed. By selectively conducting one of the first switches 811 to S 1 (k+1) in this order, the characteristics change in this order as shown by lines 29 to 31 in FIG.

In this way, a high-frequency cutoff circuit is performed.

In another embodiment of the invention, terminal 13. Is line 2
8, remove that line 28 and connect the first
Switch Sll or a nearby switch, for example S1
2 may be left short-circuited.

'ts amount adjustment variable resistance circuit 14, the second resistance R
The lower half resistance of 21 to R2, that is, R21 to R2
The total series resistance of J is determined to be, for example, IOKΩ, and the total series resistance of the upper half resistances R2(j+1) to R2 is
9 is set to Ω.

Effects As described above, according to the present invention, it is possible to reduce the number of analog switches when realized by an integrated circuit, thereby reducing cost and miniaturization. It is possible to prevent the adverse influence of resistance when the switch is turned on, and it is possible to improve the characteristics.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram of an embodiment of the present invention, Fig. fjS2 is a graph for explaining the operation of the embodiment shown in Fig. 1, and Fig. 3 is an electrical circuit diagram of an embodiment of the present invention. l! l Pneumatic diagram, 4th
Figure 5 is a graph showing the characteristics of the embodiment shown in Figure m3.
The figure is an electric circuit diagram of yet another embodiment of the present invention, and FIG. 6 is a graph showing the characteristics of the embodiment shown in FIG. 5.
The figure is an electrical circuit diagram showing the basic configuration of the high-frequency cutoff circuit.
The figure is an electric circuit diagram showing the basic configuration of the loudness circuit, and FIG. 9 is an electric circuit diagram proposed for use as a high-frequency cutoff circuit and a loudness circuit. 34...Acoustic signal source, 8...High frequency cutoff filter,
9... integrated circuit, 10... low range boost circuit, 11
...Variable resistance circuit for adjusting sound quality, 14...Variable resistance circuit for adjusting volume, 17...Switch control circuit, 18...
- Processing circuit, 23... Amplification circuit, 24... Speaker, 34... Acoustic signal source, R11-Rlk... First
Resistor, Sll-S 1 (k+1)...first switch, R21 to R2, +2... second resistor, 321 to 52
(l+1)...Second switch, S3...Third switch, R1...Resistor, CI, C2...Capacitor agent Patent attorney Number of strokes Keibu No. 2 Figure Shu; Support Kai No. 4 Inshu Arrest Chou No. 6 Figure 1%! l beach comparison

Claims (1)

[Claims] A sound quality adjustment device comprising a plurality of first resistors connected in series and a plurality of first switches having one end connected to a connection point of the first resistors and the other end connected in common. A variable volume adjustment device having a variable resistance circuit, a plurality of second resistors connected in series, and a plurality of second switches having one end connected to a connection point of the second resistors and the other end connected in common. a resistor circuit; a third switch interposed between one end of the first resistor and an intermediate position of the second resistor; and a third switch interposed between the other end of the first resistor and an intermediate position of the second resistor. a third resistor; and a circuit that selectively controls conduction/cutoff of the first to third switches; The sound quality adjustment circuit is characterized in that a capacitor or the like can be connected between the first switch and the other end, and a common connection point of the first switch is connected to the other end of the second resistor.