JPH0231886B2 - KAHENINPIIDANSUKAIRONOSEIGYOKAIRO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention enables automatic volume control after adjustment of a variable impedance circuit other than volume control, such as tone control or balance control.

Generally, audio equipment uses a large number of variable impedance circuits such as balance control, tone control, and volume control. These variable impedance circuits usually have a variable resistor connected directly to the signal transmission line, but some of them do not connect the variable resistor directly to the signal transmission line, but instead use a transistor connected to the signal transmission line. An electronic volume is also used in which impedance circuits such as the following are controlled by corresponding variable resistors.

However, when using such conventional variable impedance circuits, variable resistors corresponding to the number of variable impedance circuits are required, and the number of operation knobs for the variable resistors increases, so the area of the operation panel for car audio equipment etc. is small. This has become a major problem in the design of electronic devices. Among various operations such as balance control, tone control, and volume control in audio equipment, volume control is relatively frequently used and important.

Therefore, the present invention enables tone control, balance control, and volume control to be operated using a single variable resistor, and also enables volume control to be performed automatically even after performing tone control and balance control. .

This will be explained below with reference to the drawings.

FIG. 1 shows a conventional example.

In FIG. 1, 1 is a variable resistor H ₁ to _{H 3} which controls the output voltage of the variable resistor 1 to the respective control terminals G ₁ to H 3 .
_G3 is a hold-through gate that is held or passed depending on the control signal applied to it, _A1 to _A3 are volume controls, tone controls, and balances whose transfer impedance changes depending on the output voltage of the hold-through gates _H1 to _H3 . Control variable impedance circuits S ₁ to _{S 3} represent switches for switching control voltages of hold-through gates H ₁ to _{H 3} .

To describe the operation of this circuit, when switch S ₁ is closed and switches S ₂ and S ₃ are open, control terminal G ₁ of hold-through gate H ₁ becomes low level, and hold-through gate H ₁ enters through mode. Become.

Then, the voltage at the output terminal of the variable resistor 1 is directly supplied to the variable impedance circuit _A1 as a control signal. As a result, when the operating knob (not shown) of the variable resistor 1 is operated to change the voltage at the output terminal of the variable resistor 1, the transfer impedance of the variable impedance circuit _A1 changes accordingly, and the volume is controlled. During this time, the hold-through gates H ₂ and _{H 3} are in the hold mode and hold the output voltage of the variable resistor 1 immediately before opening _the switches S ₂ and S ₃ , respectively. Therefore, the transfer impedance of variable impedance circuits A ₂ and A ₃ can be kept constant.

For tone control, close switch S ₂ and open switches S ₁ and S ₃ .

In this case the control terminal of the hold-through gate _H2
G ₂ becomes low level, hold through gate
_H2 is in through mode.

The voltage at the output terminal of the variable resistor 1 is then directly supplied to the variable impedance circuit _A2 as a control signal. As a result, when the operating knob (not shown) of the variable resistor 1 is operated to change the voltage at the output terminal of the variable resistor 1, the transfer impedance of the variable impedance circuit _A2 changes accordingly, and tone control is performed.

The balance control can be operated in the same way as the volume control and tone control, so the explanation will be omitted.

In the conventional example described above, when changing the variable impedance for each of the volume control, tone control, and balance control adjustment, each changeover switch S ₁ , S ₂ or S ₃ is used.
Unless a variable impedance circuit is selected, it is impossible to select a variable impedance circuit, which has the disadvantage of poor operability.

In view of the fact that variable impedance circuits for volume control adjustment are used more frequently than other variable impedance circuits in such audio equipment, the present invention has been developed so that even if tone control or balance control is adjusted, volume control is automatically adjusted afterwards. It has been made possible to do so.

FIG. 2 is a block diagram of the main parts of the car audio equipment according to the first embodiment of the present invention, in which 1 is a variable resistor, 4 is an inverter, 5 is an AND circuit, and 6 to 8 are OR circuits. , H ₄ to _{H 6} are hold-through gates that hold or pass the output voltage of variable resistor 1 according to control signals applied to control terminals G ₄ to _{G 6} , and 9 to 11 are hold-through gates.
Variable impedance circuit for volume control, tone control and balance control whose transfer impedance changes according to the output voltage of H ₄ to _{H 6} , 12 and 13 are NAND circuits, 14
is a one-shot multi, 15 is a timer that responds to the output of the one-shot multi 14, Y and Z are circuit changeover switches, X is closed while variable resistor 1 is changing, and is closed while variable resistor 1 is stopped. 16 and 17 are sample and hold circuits, 18 and 19 are both comparators whose output is high level when A<B, and output is low level when A≧B, and 20 is an OR circuit. .

The operation of the circuit shown in FIG. 2 will be described.

As an initial state, circuit changeover switches Y and Z are
When the variable resistor 1 is turned OFF and the movement of the variable resistor 1 is stopped, the outputs of the comparators 18 and 19 are both low level, so the output of the OR circuit 20 is low level, and the circuit changeover switch X is in the open state.

Therefore, the output of the OR circuit 6 is at a high level.

and the control terminal G ₄ of the hold-through gate H ₄
becomes high level, hold through gate H ₄
is in the hold mode, so the transfer impedance of the variable impedance circuit 9 is kept constant.

Also, since circuit changeover switches Y and Z are OFF,
The output of the NAND circuit 13 is at a low level, and the one-shot multi 14 does not generate a pulse because the output of the NAND circuit 13 is at a low level, and the output of the timer 15 remains at a high level.

As a result, the control terminals G _{5 and} G ₆ of the hold-through gates H 5 and H ₆ become high level, and the hold-through gates H ₅ and H ₆ enter the hold mode, so that the transfer impedance of the variable impedance circuits 10 and 11 is also constant. is maintained.

Next, let's talk about volume control.

When the variable resistor 1 is rotated to the right, that is, in the direction in which the output of the variable resistor 1 increases, the output of the comparator 18 becomes high level, and the output of the comparator 1 becomes high.
Since the output of 9 becomes low level and the output of OR circuit 20 also becomes high level, the circuit changeover switch
is also turned on in conjunction with the output of variable resistor 1. However, circuit changeover switches Y and Z should remain OFF.

When the circuit changeover switch X is closed, the output of the NAND circuit 13 becomes high level. The one-shot multi 14 generates a pulse when the output of the NAND circuit 13 is inverted to high level, and the output of the timer 15 becomes low level.

Inverter 4 converts the low level output of timer 15 to high level. In addition, the NAND circuit 12
The output is at low level because circuit changeover switches Y and Z are OFF.

As a result, the output of the AND circuit 5 becomes a low level, and the output of the OR circuit 6 becomes a low level. Then, the control terminal of the hold-through gate _H4 becomes low level, and the hold-through gate _H4 enters the through mode, so the transfer impedance of the variable impedance circuit 9 changes according to the output of the variable resistor 1, and the volume is controlled. .

During volume control, the hold-through gates H ₅ and H ₆ are in the hold mode because the circuit changeover switches S ₄ and S ₅ are OFF, so the transfer impedance of the variable impedance circuits 10 and 11 is kept constant.

Next, when the variable resistor 1 is rotated to the left, that is, in a direction that decreases the output of the variable resistor 1, the output of the comparator 18 becomes low level, the output of the comparator 19 becomes high level, and the output of the OR circuit 20 Since the output voltage becomes high level, the circuit changeover switch X is also turned on in conjunction with the output of the variable resistor 1. However, circuit changeover switches Y and Z should remain OFF.

After the circuit changeover switch X is closed, the hold-through gate _H4 enters the through mode as described above, so that volume control is performed. Note that hold-through gates H ₅ and H ₆ are in hold mode, and variable impedance circuits 10 and 11
The transfer impedance of is kept constant.

Next, let's talk about tone control.

First, turn on circuit changeover switch Y and turn off Z.
shall be. When the variable resistor 1 is rotated, the circuit changeover switch X is brought into a closed state in conjunction with the variable resistor 1. Also, turn on the circuit changeover switch Y and Z.
is turned off, so the output of the NAND circuit 13 becomes high level. The one-shot multi 14 generates a pulse because the output of the NAND circuit 13 becomes high level, the output of the timer 15 becomes low level, and as a result, the output of the OR circuit 7 becomes low level. and the control terminal of hold-through gate _H5
G5 is in the through mode, and the output voltage of the variable resistor 1 is directly supplied to the variable impedance circuit 10 as a control signal, and the transfer impedance of the variable impedance circuit 10 changes according to the output voltage, and tone control is performed. It will be done.

At this time, turn on the circuit changeover switch Y and turn on the circuit changeover switch Z.
In order to turn it off, the output of the timer 15 is at a low level, and a high level is input to the OR circuit 6 via the inverter 4 and the AND circuit 12, which outputs a high level. Also, OR circuit 8 is switch Z
Since is OFF, the output is set to high level regardless of the operation of timer 15.

As a result, since the control terminals G ₄ and G ₆ are at high level, the hold-through gates H ₄ and H ₆ are in the hold mode, and the hold-through gates H ₄ and H ₆ continue to hold the previously set output voltage. Therefore,
The transfer impedance of variable impedance circuits 9 and 11 is kept constant.

Regarding the balance control, the explanation of the operation is the same as that of the tone control except that the circuit changeover switch Z is turned on and the circuit changeover switch Y is turned off, so a description thereof will be omitted.

FIG. 3 is a block diagram of the main parts of a car audio device according to a second embodiment of the present invention. In the figure, 2 is formed by connecting resistors R ₁ to _{R o} in series between the power supply and the ground. DC voltage generator and the resistor
A regulating voltage generator consisting of switches S ₀ to _{S o} connected between each connection point of R ₁ to _{R o} and output terminal 3, 4 an inverter, 5 an AND circuit, 6 to 8 an OR circuit,
H ₄ to _{H 6} are hold-through gates that hold or pass the output voltage of the regulated voltage generator 2 according to control signals applied to control terminals G ₄ to _{G 6} ; 9 to 11 are hold-through gates H ₄ to _{H 6} Variable impedance circuits for volume control, tone control, and balance control whose transfer impedance changes according to the output voltage of 12 and 1.
3 is a NAND circuit, 14 is a one-shot multi, 1
5 is a timer that responds to the output of the one-shot multi 14, Y and Z are circuit changeover switches, and X is a switch.
It shows a switch that closes in conjunction with closing any one of S ₀ to S _o .

The operation of the circuit shown in FIG. 3 will be described.

As an initial state, circuit changeover switches Y and Z are
When it is turned OFF and the switches S ₀ to S _o are opened, the circuit changeover switch X is also opened. As a result, the output of the OR circuit 6 becomes high level. Then, the control terminal of hold-through gate _H4 becomes high level,
Since the hold-through gate _H4 is in the hold mode, the transfer impedance of the variable impedance circuit 9 is kept constant. At this time, in order to turn off the circuit changeover switches Y and Z, the NAND circuit 13
The output of the timer 15 becomes low level, the one shot multi 14 does not generate a pulse because the output of the NAND circuit 13 is low level, and the output of the timer 15 remains high level.

Also, since switches Y and Z are off, the control terminals G ₅ and G ₆ of the hold-through gates H ₅ and H ₆ are always at high level, and the hold-through gates H ₅ and H ₆
is in the hold mode, so the transfer impedance of the variable impedance circuits 10 and 11 is also kept constant.

Next, let's talk about volume control.

When an arbitrary switch in the switch group 2 is closed and turned ON, the circuit changeover switch X is brought into the closed state in conjunction with this.

However, circuit changeover switches Y and Z should remain OFF.

When the circuit changeover switch X is closed, the output of the NAND circuit 13 becomes high level. The one-shot multi 14 generates a pulse when the output of the NAND circuit 13 is inverted to high level, and the output of the timer 15 becomes low level.

Inverter 4 converts the low level output of timer 15 to high level. Further, the output of the NAND circuit 12 is at a low level because the circuit changeover switches Y and Z are OFF.

As a result, the output of the AND circuit 5 becomes a low level, and the output of the OR circuit 6 becomes a low level. Then, the control terminal of the hold-through gate _H4 becomes low level, and the hold-through gate _H4 enters the through mode, so the transfer impedance of the variable impedance circuit 9 also changes according to the output of the adjustment voltage generator 2, and the volume is controlled. Ru.

During volume control, hold-through gates H ₅ and H ₆ have circuit changeover switches Y and Z OFF.
Therefore, the transfer impedance of the variable impedance circuits 10 and 11 is kept constant since the hold mode is established.

Next, let's talk about tone control.

Turn circuit changeover switch Y OFF and turn Z ON.

At this time, the output of the NAND circuit 13 becomes high level, and since the output of the NAND circuit 13 is high level, the one-shot multi 14 generates a pulse, and the timer 15 uses this pulse to set the output to low level.

As a result, the OR circuit 7 outputs a low level,
The control terminal _G5 of the hold-through gate _H5 becomes low level, and tone control is performed.

During tone control, the circuit changeover switch Z is open and the control terminals G ₄ and G ₆ are at high level, so the hold-through gates H ₄ and H ₆ are in the hold mode, and the variable impedance circuits 9 and 11 are in the hold mode. Transfer impedance is kept constant.

Regarding the balance control, the explanation of the operation is the same as that of the tone control except that the circuit changeover switch Z is turned on and the circuit changeover switch Y is turned off, so a description thereof will be omitted.

The embodiments of the present invention have been described above, but by using the present invention, not only can various operations such as volume control, tone control, and balance control be performed with one variable resistor, but also tone control, balance control, etc. After adjusting the variable impedance other than equal volume control, volume control can be easily performed without operating the volume control switch, which simplifies the switching operation and is extremely convenient.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional example, FIG. 2 is a block diagram of a first embodiment of the present invention, and FIG. 3 is a block diagram of a second embodiment of the present invention. 1... Variable resistor, 2... Adjustment voltage generator, 3
... Output terminal of adjustment voltage generator, 4 ... Inverter, 5 ... AND circuit, 6 to 8 ... OR circuit, 9
~11...variable impedance circuit, 12,13
...Nand circuit, 14...One shot multi,
15...Timer, 16,17...Sample hold circuit, 18,19...Comparator, 20...
OR circuit.

Claims (1)

[Claims] 1 A regulated voltage generator, a plurality of hold-through gates connected to the regulated voltage generator and capable of holding or passing the output of the regulated voltage generator, and each connected to the output side of the plurality of hold-through gates. a variable impedance circuit in which the transfer impedance of the signal transmission path changes according to the respective outputs; a control means for supplying a hold signal or a through signal to control terminals of the plurality of hold-through gates; means for selecting a predetermined hold-through gate from among the plurality of hold-through gates in response to an operation; and selection means for selecting a hold-through gate other than the predetermined hold-through gate to which a through signal should be supplied; The means is configured to always supply a through signal to the predetermined hold-through gate in response to the operation of the adjustment voltage generator when a hold-through gate other than the predetermined hold-through gate is not selected by the selection means. A control circuit for a variable impedance circuit featuring: