JPH0231887B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a level control device, and in particular to a level control device that can control a plurality of variable impedance circuits and display a level by selectively switching control levels of the plurality of variable impedances by operating a switch. Relating to a control device.

Generally, in audio equipment, a large number of variable impedance circuits are used, such as bass control, treble control, balance control, and volume control. In these variable impedance circuits, a variable resistor is usually connected directly to a signal transmission path. However, when such variable impedance circuits are used, variable resistors corresponding to the number of variable impedance circuits are required, and operation knobs corresponding to the number of variable impedance circuits are required. This is a major constraint in terms of panel design in audio equipment where the area of the operation panel is small, such as in-vehicle audio equipment.

The present invention provides a solution to the above-mentioned drawbacks and provides a level control device that can control a plurality of variable impedance circuits by operating a small number of switches.

Hereinafter, the present invention will be explained using examples thereof.
FIG. 1 is a block diagram of main parts of an audio device showing one embodiment of the present invention, in which 1 indicates an up switch 1a and a down switch 1b for increasing and decreasing the impedance of each variable impedance circuit 21, 22, 23. A push button switch consisting of 2 and 3
is a NAND circuit, 3 is a pulse oscillator with a strobe, 4 is a delay pulse generator for delay,
5 is an OR circuit, 7 is a variable impedance circuit 2
Level setting push button switch for setting each impedance value of 1, 22, 23, 8
1 is a code converter that outputs predetermined data when one of the push button switches 7 is pressed; 9, 10, and 11 are adder/subtractors;
3 and 14 are gate circuits; 15, 16, and 17 are switches for switching sound quality control, balance control, volume control, etc.;
18, 19, 20 are D-A converters, 21, 2
2 and 23 are variable impedance circuits.

Note that 24 is a switch that is switched in conjunction with switches 15, 16, and 17, 25 is a drive circuit for driving a display device 26, and 26 is a display device comprising, for example, a light emitting diode.

FIG. 2 is a front view of the main parts of the audio equipment related to FIG. 1, where 1a and 1b are the operating knobs 7a, 7b, and 7c of the push button switch 1, and 15', 16', and 17' are the operating knobs 15', 16', and 17' of the push button switch 7, respectively. is switch 15, 16,
The operating knob 17 and 26' are a display device 26 made of, for example, a light emitting diode.

The operation of the level control device configured as described above will be explained. First, sound quality control will be explained. Switch 15 is closed, and switches 16 and 17 are left open.

In this state, for example, the switch 7 for setting the higher control level among the push button switches 7 for setting three control levels: high, middle, and low.
When a is pressed, the code converter 8 outputs predetermined data indicating a high level, and this output causes the gate circuit 12 to send data for setting the sound quality to a control level indicating a high level. The signal is output to the A converter 18, and the variable impedance circuit 21 for sound quality control is set to a high control level. At this time, the output of the NAND circuit 6 of the adder/subtractor 9 is HI, and therefore the adder/subtracter 9 is in a standby state due to the HI signal input to the CS terminal of the adder/subtractor 9, and its output is off. After this, when the switch 1a of the push button switch 1 is closed to increase the impedance of the variable impedance circuit 21, for example, the output of the NAND circuit 2 becomes HI, and the pulse oscillator 3 outputs a predetermined pulse signal. . The pulse signal is
is input to the gate circuit 12 via the OR circuit 5,
In addition, push button switch 1a is connected to the up terminal of adder/subtractor 9.
When the control level setting switch 7a is pressed first, the output from the gate circuit 12 is input to the IN terminal of the adder/subtractor 9, and the data at this time is inputted to the IN terminal of the adder/subtractor 9. Addition or subtraction is performed in the adder/subtractor 9 as a reference. Then, this added and subtracted data is
The gate circuit 12 and the D-A converter 1 are output from the OUT terminal for each pulse from the pulse oscillator 3.
The signal is inputted to the variable impedance circuit 21 via 8, and the impedance is controlled to obtain the desired sound quality. Note that while the above-mentioned sound quality control is being performed, the switches 16 and 17 are open, and the respective gate circuits 13 and 14 are in a hold state, and the previously set respective output signals are held. . Therefore, the transfer impedance of the variable impedance circuits 22 and 23 is kept constant, and the balance and volume are not changed.

Next, balance control will be explained. At this time, close switch 16 and switch 1
5 and 17 are left open. By closing the switch 16, the gate circuit 13 is switched from the hold state to the through state. After this, when one of the push button switches 7, for example, the push button switch 7c for setting the control level is pressed in order to emphasize the right channel, a signal is inputted to the CS terminal of the adder/subtractor 10 via the NAND circuit 6 in the same manner as described above. As a result, the adder/subtractor 10 is in a standby state and the output is off. Further, predetermined data from the code converter 8 is input to the variable impedance circuit 22 via the gate circuit 13 and the DA converter 19.
Set to the right channel emphasis level. After this, when switch 1b of the push button switches 1 is pressed to make fine adjustments to further emphasize or weaken the right channel emphasis within the control range, the pulse signal from the pulse oscillator 3 is sent to the gate circuit 13 via the OR circuit 5. The pulse signal is input to the adder/subtractor 10 via the gate circuit 13, where it is subtracted from the data from the switch 7a, and the subtracted data is again input to the gate circuit 13.
The data is input to the variable impedance circuit 22 via the D-A converter 19,
The impedance of the variable impedance circuit 22 is reduced to achieve the desired balance control.

Note that while the balance control is being performed, the switches 15 and 17 are open, and the gate circuits 12 and 14 are in a hold state, so that the previously set output signals are held. Therefore, variable impedance circuits 21, 23
The transfer impedance of is kept constant and the tone and volume do not change.

Next, regarding the volume control, in this case, close switch 17 and turn switch 1.
Leave numbers 5 and 16 open. The subsequent operations are the same as those for tone control and balance control, and will not be described in detail, but volume control is accomplished by operating push button switches 7 and 1.

In addition, the contacts 24a and 2 of the switch 24 are
4b, 24c are switches 15, 16, respectively.
It is turned on and off in conjunction with D-A converter 17, and by being turned on, data from one of the D-A converters 18, 19, and 20 is input to the drive circuit 25,
The signal is converted into a signal for driving the display device 26, and the display device 26 is driven.

As described above, according to the level control device of the present invention, the first operating means for increasing or decreasing the impedance of the signal transmission path for each pulse signal;
a second operation means consisting of a plurality of switches for setting a rough level of impedance of the signal transmission path; a pulse oscillation means for generating the pulse signal; and a second operation means for each switch of the second operation means. code converting means for outputting predetermined data in response to opening/closing; a plurality of addition/subtraction means for performing addition/subtraction based on data from the code converting means and data from the first operation procedure; and the addition/subtraction means. a plurality of gate means for holding or passing data from the gate means, a plurality of variable impedance circuits in which the transfer impedance of the signal transmission path changes according to the data from the gate means, and any one of the plurality of gate means. a first selection means for selecting and setting it in a passing state; a second selection means for selecting one output of the plurality of gate means in conjunction with the first selection means; and the second selection means and a display device for displaying an output selected by the gate circuit, and the output of the selected gate circuit is supplied as a control signal to the corresponding variable impedance circuit, and is also supplied to the display device as a display signal. Therefore, by using only the output of the gate means selected by the two selection means as a control signal and a display signal, multiple control levels can be selectively displayed depending on the purpose of use, and a single display device can be used. can be used to display multiple levels, reducing the display space. Furthermore, since the circuit configuration becomes simple, it is possible to reduce costs, which has a great practical effect.

Note that the pulse interval from the pulse oscillator 3 may be controlled to be variable, and the speed of fine adjustment may be adjusted.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of an audio equipment showing one embodiment of the present invention, and FIG. 2 is a front view of the main parts of the audio equipment related to FIG. 1, 7...Push button switch, 2, 6...NAND
Circuit, 3...Pulse oscillator, 5...OR circuit, 8
...Code converter, 9,10,11...Adder/subtractor, 12,13,14...Gate circuit, 15,1
6, 17, 24...Switch, 18, 19, 20
...D-A converter, 21, 22, 23... Variable impedance circuit, 26... Display device.

Claims (1)

[Claims] 1. A first operating means for increasing or decreasing the transfer impedance of the signal transmission path for each pulse signal, and a second operating means consisting of a plurality of switches for setting the rough level of the transfer impedance of the signal transmission path. , a pulse oscillation means for generating the pulse signal, a code conversion means for outputting predetermined data in response to opening and closing of each switch of the second operation means, and a code conversion means for outputting predetermined data in response to opening and closing of each switch of the second operation means; a plurality of addition and subtraction means for performing addition and subtraction according to data from one operation means; a plurality of gate means for holding or passing data from the addition and subtraction means; and a plurality of gate means for holding or passing data from the addition and subtraction means; a plurality of variable impedance circuits in which the transfer impedance of the transmission line changes; a first selection means for selecting one of the plurality of gate means to put it in a passing state; A second selection means for selecting one output of a plurality of gate means, and a display device for displaying the output selected by the second selection means, the output of the selected gate circuit being variable. A level control device characterized in that the level control device is configured to supply a control signal to the impedance circuit and also to the display device as a display signal.