JPH0110008Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a volume adjustment circuit used in audio equipment and the like, and particularly relates to a volume adjustment circuit in which the volume is adjusted by operating a push button or the like.

2. Description of the Related Art Conventionally, as this type of push button type volume adjustment circuit, one shown in FIG. 1 is known. The volume adjustment circuit shown in this figure amplifies a signal supplied to an input terminal 1 by an amplifier 2 and outputs the sound from a speaker 3. A voltage-controlled amplifier ( (hereinafter referred to as VCA)
4 is inserted, and while the push button switch 5 for the volume increase command is pressed, the output (clock signal) of the clock generation circuit 6 is added and counted, and the push button switch 7 for the volume decrease command is pressed. an up-down counter 8 that subtracts and counts the clock signal while the up-down counter 8
A digital-to-analog converter (hereinafter referred to as a D/A converter) that converts the counted contents into a corresponding value of voltage.
9 is provided, and the output voltage of this D/A converter 9 is
By supplying the gain control voltage to the VCA 4, the volume increases when the push button switch 5 is pressed, and decreases when the push button switch 7 is pressed.

However, in the conventional volume adjustment circuit shown in FIG. 1, the count content of the up-down counter 8 changes in proportion to the pressing time of the push button switch 5 or the push button switch 7, so the volume cannot be adjusted. There is a drawback that when changing, it takes time depending on the amount of change. Although this problem can be solved by shortening the period of the clock signal, this poses a problem in that it becomes difficult to finely adjust the volume. Also,
In such a conventional volume adjustment circuit, the count contents of the up-down counter 8 are lost when the power is turned off, so in order to obtain a predetermined volume when the power is turned on, the power supply must be turned off as shown in Figure 1. A preset circuit 10 must be provided to set the count of the up-down counter 8 to a predetermined value when the power is turned on.

In view of the above circumstances, this invention aims to provide a push-button volume adjustment circuit that can instantly obtain a predetermined volume and also finely adjust the volume. A first voltage setting circuit which converts the counted contents of an up-down counter into a voltage by a D/A converter and outputs the voltage, which is added or subtracted according to the voltage, and a plurality of voltages set by a variable resistor. a second voltage setting circuit that outputs a voltage of It is equipped with a variable gain amplifier whose gain is changed by the output of the voltage selection circuit, and can instantly select the volume corresponding to the voltage set by the variable resistor, as well as issue a volume increase command and a variable gain amplifier. The volume can also be finely adjusted by issuing a volume reduction command.

Hereinafter, embodiments of this invention will be described in detail with reference to the drawings.

FIG. 2 is a circuit diagram showing the configuration of a first embodiment of this invention, and in this figure, parts corresponding to those in FIG. 1 are given the same reference numerals. Second
In the figure, a push button switch 5 for volume increase command,
A portion consisting of a push button switch 7 for volume reduction command, a clock generation circuit 6, an up-down counter 8, a D/A converter 9, and a preset circuit 10 constitutes a first voltage setting circuit 11. The configuration of this voltage setting circuit 11 is the same as the control voltage generation portion of the VCA 4 in FIG. Reference numeral 12 is a second voltage setting circuit, and this voltage setting circuit 12 is
A reference voltage generator 13 that generates a reference voltage of a predetermined value from a power supply +B, and three variable resistors 14 to 16 inserted in parallel between the output end of this reference voltage generator 13 and a ground point. The voltage is taken out from each sliding terminal of these variable resistors 14 to 16. Next, reference numeral 17 indicates the output voltage of the D/A converter 9 in the voltage setting circuit 11 and the variable resistors 14 to 17 in the voltage setting circuit 12.
This is a voltage selection circuit for selecting any one voltage from the voltages output from each of the 16 sliding terminals.
In this voltage selection circuit 17, 18 _-1 to 18 _-4
are momentary type push button switches, and the push button switch 18 _-1 selects the output of the D/A converter 9, and the push button switches 18 _-2 to 18 _-4 select the respective sliding terminals of the variable resistors 14 to 16. are provided for selecting the outputs obtained in each case. One contact point of each of these push button switches _18-1 to _18-4 is commonly connected and grounded, and each other terminal is connected to the selector 1.
9 input terminals _I1 to _I4 , respectively. When the ground potential is supplied to any one of the input terminals I ₁ to _{I 4} , the selector 19 outputs the output terminal.
Among _D1 to _D4 , the output terminal corresponding to the input terminal to which the ground potential is supplied is held exclusively at the ground potential, and among the output terminals _O1 to _O4 , the ground potential is not supplied. A drive signal is exclusively output from an output terminal corresponding to the input terminal, and this drive signal is held. The input terminal _I3 of this selector 19 is connected to an initialization circuit 20 which outputs a ground potential signal of a predetermined time width when the power is turned on.
is connected to the output terminal of Also output terminal D ₁
~ _D4 , the anode is connected to the power supply +B via the resistor 21
It is connected to each cathode of light emitting diodes 22 _-1 to 22 _-4 connected to. Each drive signal output from the output terminals O ₁ to O ₄ is supplied as a contact drive signal to each switch 24 _-1 to 24 _-4 (normally open switch) in the analog switch circuit 23. The contacts of each of the switches 24 _-1 to 24 _-4 are an output terminal of the D/A converter 9, a sliding terminal of the variable resistor 14, a sliding terminal of the variable resistor 15,
are connected to the sliding terminals of the variable resistor 16, and the other contacts of the switches _24-1 to _24-4 are
They are commonly connected and connected to the control input terminal of VCA4 (variable gain amplifier).

Moreover, FIG. 3 is a front view of the operation panel in the above embodiment, and the push button switches 5, 7, _18-1
18 _-4 and the respective knobs 14a to 16a of the variable resistors 14 to 16 are arranged as shown in this figure. In addition, push button switches 18 _-1 to 18
The light emitting diodes 22 _-1 to 22 _-4 are provided inside each push button _-4 to illuminate each of these push buttons.

Next, the operation of this embodiment with the above configuration will be explained. When the push button switch _18-1 is pressed, the light emitting diode _22-1 lights up and the push button switch _18-1 is illuminated, and at the same time, the switch _24-1 is turned on. ₁
is closed. As a result, the output voltage of the D/A converter 9 is supplied to the VCA 4, so pressing the push button switch 5 increases the volume, and pressing the push button switch 7 decreases the volume.
That is, in this case, the volume can be finely adjusted manually by pressing the push button switches 5 and 7. When the push button switch _18-2 is pressed, the light emitting diode _22-2 lights up to illuminate the push button switch _18-2 , and the switch _24-2 is closed. As a result, variable resistor 1
Since the voltage at the sliding terminal 4 is now supplied to the VCA 4, the volume corresponding to the voltage preset by the variable resistor 14 is immediately selected.
Also, push button switch _18-3 or push button switch 1
When _8-4 is pressed, the volume corresponding to the voltage preset by variable resistor 15 or variable resistor 16 is immediately selected, as in the above case. In this case, the voltages V ₁ , V ₂ , V ₃ obtained at the sliding terminals of the variable resistors 14 to 16 are set by the knobs 14a to 16a so that V ₁ <V ₂ <V ₃ . If you put it, push button switch 18 _-2 , 18
As you operate _-3 , 18 _{and -4} in order, the volume will increase step by step.

Note that in this embodiment, the initialization circuit 20
Therefore, when the power is turned on, the volume corresponding to the voltage set by the variable resistor 15 is automatically selected. Further, in this embodiment, since the initialization circuit 20 is provided, the preset circuit 10 is not necessarily required.

Next, FIG. 4 is a circuit diagram showing the configuration of a second embodiment of this invention. The configuration of this second embodiment differs from that of the first embodiment in the following points. That is, variable resistors 14 to 16
In addition to this, a variable resistor 25 is newly added. The output voltage of the D/A converter 9 and the output voltage of the reference voltage generator 13 supplied via the resistor 27 are supplied from the adder circuit 26 to the non-grounded sides of these variable resistors 14 to 16, 25. The sum of the voltages is supplied. The voltage obtained at the sliding terminal of variable resistor 25 is supplied to one terminal of switch 24 _-1 . Further, the output terminal of the initialization circuit 20 is connected to the input terminal I2 of the selector 19, and the output terminal of the initialization circuit 20 is connected to the input terminal _I2 of the selector 19.
0 has been removed. Note that terminal 28 is VCA4
This terminal is connected to a control input terminal (not shown).

FIG. 5 is a front view of the operation panel in this second embodiment, and in this figure, the knob 25a is the knob of the variable resistor 25.

In the above configuration, when the push button switch 18 _-1 is pressed, the switch 24 _-1 is closed and the voltage obtained at the sliding terminal of the variable resistor 25 is supplied to the terminal 28 . As a result, the volume corresponding to the preset position of the variable resistor 25 is immediately selected, and from this state the push button switch 5 is pressed.
Alternatively, by pressing the push button switch 7, the volume preset by the variable resistor 25 can be finely increased or decreased in accordance with the operation of the push button switches 5 and 7. Also, push button switch 18 _-2
18 _-4 is pressed, the volume corresponding to the preset position of the variable resistors 14 to 16 is immediately selected in the same way as the above operation, and if push button switch 5 or push button switch 7 is pressed from this state, This preset volume can be finely increased or decreased.

In this embodiment, the volume corresponding to the preset position of the variable resistor 14 is automatically selected by the action of the initialization circuit 20 immediately after the power is turned on.

As is clear from the above explanation, the volume adjustment circuit according to this invention uses a D/A converter to handle the count contents of the up-down counter, which performs addition and subtraction counts in response to volume increase and decrease commands. a first voltage setting circuit that outputs a voltage set by a variable resistor; a second voltage setting circuit that outputs a plurality of voltages set by a variable resistor; It is constructed by providing a voltage selection circuit that selects any one voltage from a plurality of voltages obtained based on each output voltage, and a variable gain amplifier whose gain is changed depending on the output of this voltage selection circuit. Therefore, the volume preset by the variable resistor can be immediately selected, and the volume can also be finely adjusted by the volume increase command and the volume decrease command. In particular, when the voltage selection circuit is configured to select any one voltage from each output voltage of the second voltage setting circuit to which the output voltage of the first voltage setting circuit is added, the variable resistor Therefore, a preset volume can be immediately selected, and at the same time, the selected volume can be finely adjusted by a volume increase command and a volume decrease command.

In addition, this invention provides that if the voltage selection circuit is configured to automatically select a specific voltage when the power is turned on, the volume after the power is turned on can be set using an extremely simple circuit without the need for a memory device or the like. This is particularly effective for audio equipment that starts a timer.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an example of the configuration of a conventional volume adjustment circuit, Figure 2 is a circuit diagram showing the configuration of a first embodiment of this invention, and Figure 3 is a front view of the operation panel in the same embodiment. 4 is a circuit diagram showing a second embodiment of this invention, and FIG. 5 is a front view of the operation panel in the same embodiment. 4...variable gain amplifier (voltage controlled amplifier),
8...Up-down counter, 9...Digital-to-analog converter, 11...First voltage setting circuit, 1
2... Second voltage setting circuit, 17... Voltage selection circuit.

Claims (1)

[Claims for Utility Model Registration] (1) The count contents of an up-down counter, which performs addition and subtraction in response to volume increase and decrease commands, are converted into corresponding voltage values by a digital-to-analog converter. a first voltage setting circuit that outputs a plurality of voltages set by a variable resistor; and a second voltage setting circuit that outputs a plurality of voltages set by a variable resistor; and a variable gain amplifier whose gain is changed according to the voltage selected by the voltage selection circuit. volume adjustment circuit. (2) The voltage selection circuit selects any one voltage from the output voltage of the first voltage setting circuit and each output voltage of the second voltage selection circuit. The volume adjustment circuit described in item 1. (3) The voltage selection circuit selects any one voltage from among the output voltages of the second voltage setting circuit to which the output voltages of the first voltage setting circuit are added. Claim 1
Volume adjustment circuit described in section.