JPH0244165B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a volume adjustment circuit used in audio equipment and the like, and particularly to a volume adjustment circuit that adjusts the volume by pressing a lead.

This type of volume adjustment circuit includes a push button switch for increasing the volume and a push button switch for decreasing the volume, a counter that adds or subtracts the clock signal when these push buttons are pressed, and a counter that counts the clock signal by adding or subtracting, respectively. A variable gain amplifier circuit whose gain changes depending on the data is provided, and the input signal is outputted through the variable gain amplifier circuit.

By the way, in this type of volume adjustment circuit,
When the power of the device (such as an audio device equipped with this volume adjustment circuit) is cut off, the counting data of the counter is lost, so when the power is turned on, the volume must be adjusted again by operating the push button switch, which is an inconvenience. There is. For this reason, there is a demand for this type of volume adjustment circuit to be able to obtain a desired volume immediately when the power is turned on. On the other hand, in this type of volume adjustment circuit, since the amount of change in volume is proportional to the pressing time of the push button switch, it takes a long time to make a large change in volume. Therefore, there is an inconvenience that, for example, if you want to suddenly turn down the volume when a visitor arrives or when you receive a telephone call, you cannot respond immediately. For this reason, there is a desire for this type of volume adjustment circuit to be able to change the volume instantly and significantly even when the power is turned on.

The present invention aims to provide a volume adjustment circuit that can satisfy both of the above-mentioned demands, and includes a counter that presets data when a load signal is supplied, and a gain that corresponds to the count data output by this counter. a variable gain amplifier circuit that amplifies and outputs an input signal; a first time constant circuit that supplies a load signal to the counter when power is turned on and stops supplying the load signal after a time period corresponding to a time constant; a second time constant circuit that outputs a first drive signal when the circuit is turned on and stops outputting the first drive signal after a time period corresponding to a time constant greater than a time constant of the first time constant circuit; A first preset data output circuit outputs first data to the counter when a drive signal of 1 is supplied, and a second preset data output circuit supplies the load signal to the counter when a preset switch is operated. The apparatus includes a preset switch means for outputting a drive signal, and a second preset data output circuit for outputting second data to the counter when the second drive signal is supplied.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention. In this figure, 1 is an up-down type binary counter (counter) that performs binary counting and is capable of data presetting. This counter 1 is connected to the enable input terminal CE.
If a “0” signal is supplied to the control input terminal U/D, the clock signal supplied to the clock input terminal CK
CLOCK is added and counted, and if a "1" signal is supplied to the control input terminal U/D, the clock signal is
CLOCK is subtracted and counted, and this count data is output as a binary code (a binary code in which a "1" signal is true) from data output terminals A to E. Also, this counter 1 has 2 inputs to the load input terminal LD.
“0” of value logic signal (binary logic signal with positive potential signal as “1” signal and ground potential signal as “0” signal)
When the signal is supplied, the 5-bit data (the "1" signal is considered true) is supplied to the data input terminals a to e (data input terminal a corresponds to the most significant bit and data input terminal e corresponds to the least significant bit). (binary code) and preset it. A clock generating circuit 2 generates a clock signal CLOCK of a predetermined period to be supplied to the clock input terminal CK of the counter 1. 3 is a push button switch for increasing the volume,
4 is a push button switch for reducing the volume; one contact point of each of these push button switches 3 and 4 is grounded;
Each other contact is the input terminal 5a of the counting control circuit 5,
5b, respectively. The counting control circuit 5 is
When the input terminal 5a is grounded, the output terminals 5c and 5d
When the input terminal 5b is grounded, the output terminal 5c outputs a "1" signal, the output terminal 5d outputs a "0" signal, and both input terminals 5a and 5b are grounded. If not, the configuration is such that a "1" signal is output from the output terminal 5d. Output terminal 5 of this counting control circuit 5
c, 5d are control input terminals U/D of the counter 1.
and enable input terminal CE, respectively. Reference numeral 6 designates a first preset circuit for presetting data (first data) corresponding to a desired volume into the counter 1 when a device equipped with this volume adjustment circuit is powered on. In this preset circuit 6, 7 is a switch group for determining the above data, and this switch group 7 is made up of five switches _7-1 to _7-5 . Reference numeral 8 denotes a power supply terminal to which power supply voltage +B of a device equipped with this volume adjustment circuit is supplied, and the power supply voltage +B of this power supply terminal 8 is supplied to each part of this volume adjustment circuit. A resistor 10 (value:
R ₁ ) and a capacitor 11 (value C ₁ ) are successively inserted in series, and at the same time, a resistor 13 (value R ₂ ) and a capacitor 14 (value C ₂ ) forming the integrating circuit 12 are successively inserted in series. ing. The connection point between the resistor 10 and the capacitor 11 is connected to the load input terminal LD of the counter 1, and the connection point between the resistor 13 and the capacitor 14 is common to one contact point of each of the switches _7-1 to _7-5 . It is connected. Switch 7 _-1 ~7
The other contacts of _-5 are connected to data input terminals a to e of counter 1, respectively. 15, when the device equipped with this volume adjustment circuit is operating,
This is a second preset circuit for presetting the counter 1 with data (second data) corresponding to the volume desired by the operator. In this preset circuit 15, numeral 16 is a switch group for determining the above data, and this switch group 16 consists of five switches 16 _-1 to 16 _-5 . 17
is a push button switch (preset switch) which is operated when presetting the data determined by the switch group 16 into the counter 1. One contact of this push button switch 17 is grounded, and the other contact is connected to one end of a resistor (pull-up resistor) 18 and the cathode of a diode 19, and is commonly connected to one contact of each of the switches 16 _-1 to 16 _-5 . has been done. The other end of the resistor 18 is connected to the power supply terminal 8,
The anode of the diode 19 is connected to the load input terminal LD of the counter 1. Also switch 1
The other contact point of each of 6 _-1 to 16 _-5 is a diode 20
_-1 to 20 _-5 cathodes, respectively, and anodes of these diodes 20 _-1 to 20 _-5 are connected to data input terminals a to e of the counter 1, respectively. Reference numeral 21 denotes a variable gain amplification circuit that amplifies the signal supplied to the signal input terminal 22 (signal for which the volume should be adjusted) with a gain corresponding to the count data outputted by the counter 1 and outputs it from the signal output terminal 23. In this variable gain amplifier circuit 21, 24 is a D/A
This D/A converter 24 is a converter (digital-to-analog converter), and the D/A converter 24 includes resistors 25 _-1 to 2 whose one end is connected to the data output terminals A to E of the counter 1, respectively.
5 _-5 and the other ends of the resistors 25 _-1 and 25 _-2 , between the other ends of the resistors 25 _-2 and 25 _-3 , and the resistor 25
_-3 , 25 _-4 between the other ends of said resistors 25 _-4 , 25 _-5
Resistors 26 _-1 to 26 _-4 respectively connected between the other ends of
and a resistor 27 connected between the connection point of the resistors 25 _-1 and 26 _-1 and the ground point. In this case, these resistors 25 _-1 to 25 _-6 , 26 _-1 to 2
The respective resistance values of 6 _-4 and 27 are such that the analog voltage obtained at the connection point of resistors 25 _-5 and 26 _-4 is proportional to the value of count data output from data output terminals A to E of counter 1. configured to change.
A connection point between the resistors 25 _-5 and 26 _-4 is connected to a control input terminal 28C of a voltage controlled amplifier (hereinafter simply referred to as VCA) 28. The input terminal 28a of the VCA 28 is connected to the signal input terminal 22, and
The output terminal 28b of the VCA 28 is the signal output terminal 23
It is connected to the.

Next, the operation of this volume adjustment circuit having the above configuration will be explained.

Now, when a device equipped with this volume adjustment circuit is powered on, the power supply voltage at the terminal 8 rises from zero (V) to +B (V). At this time, the voltage at the connection point of resistor 10 and capacitor 11 and the voltage at the connection point of resistor 13 and capacitor 14 are respectively time constant R ₁ · C ₁ and time constant R ₂ ·C with respect to the power supply voltage +B. The voltage +B is reached with a delay of time corresponding to ₂ . Here, the time constant R ₂ · C ₂ is set larger than the time constant R ₁ · C ₁ , so when the power is turned on, a “0” signal is transiently supplied to the load input terminal LD of counter 1, and at that time, Data determined by the open/closed states of switches _7-1 to _7-5 (closed state is "1" and open state is "0") is preset in counter 1, and as a result, it is output from signal output terminal 23. The volume of the signal has a value corresponding to the data determined by the open/closed states of the switches 7 _-1 to 7 _-5 . In addition, under normal conditions after the power is turned on, a "1" signal is supplied to the load input terminal LD, and when push button switch 3 is pressed in the normal up-down count mode, the count data at counter 1 is As a result, when the push button switch 4 is pressed, the count data of the counter 1 decreases according to the pressing time, and as a result, the sound volume decreases. Also, when the push button switch 17 is pressed, the load input terminal LD becomes a "0" signal, and in this case, the switch 16 is pressed.
The data determined by the open/closed state of switches 16 _-1 to _{16 -5} (closed state is "1" and open state is "0") is preset to counter 1, and as a result, the volume is set to 16 _-1 to 16 The value corresponds to the data determined by the open/close status of _-5 .

As described above, according to this embodiment, the volume obtained immediately after the power is turned on can be automatically adjusted to an arbitrary amount determined by the switches _7-1 to _7-5 . By pressing the switches 3 and 4, the volume can be increased or decreased as desired. Furthermore, if necessary, press the push button switch 1.
By pressing 7, switches 16 _-1 to 16
Can be instantly adjusted to any amount determined by _-5 .

Next, FIG. 2 is a circuit diagram showing a first modification of the embodiment shown in FIG. 1. In the modification shown in FIG. 2, when push button switch 17 is pressed, data input terminals a to e of counter 1 are all grounded via diodes 20 _-1 to 20 _-5 .

Note that FIG. 3 shows an example of the arrangement of the push button switches 3, 4, and 17 in FIG. 2 on an operation panel (not shown).

According to the configuration shown in FIG. 2, the volume when the power is turned on is determined by the open/closed states of the switches _7-1 to _7-5 , and the volume during normal operation can be adjusted to any value using the pushbutton switches 3 and 4. Also, push button switch 17 (push button switch for muting)
You can immediately reduce the volume to zero by pressing . This push button switch 17 is convenient to use, for example, when a visitor arrives or when a telephone call arrives.

Next, FIG. 4 is a circuit diagram showing a second modification of the embodiment shown in FIG. 1. The modification shown in this figure differs from the previous embodiment in the following points. That is, when the push button switch _17-1 is pressed, the data input terminals a to e of the counter 1 are grounded via the diodes _20-11 to _20-15 , and the load input terminal LD is grounded via the diode _19-1 , thereby reducing the volume. becomes zero. Also push button switch 17 _-2
When is pressed, only the data input terminals b and d are grounded via diodes 20 _-22 and 20 _-24 , and the load input terminal LD is grounded via diode 19 _-2 , so that the volume becomes moderate. Further, when the push button switch _17-3 is pressed, only the data input terminal d is grounded via the diode _20-34 , and the load input terminal LD is grounded via the diode _19-3 , making the volume relatively high.

Incidentally, FIG. 5 shows an example of the arrangement of the push button switches 3, ₄ , 17-1, _17-2 , and _17-3 in FIG. 4 on the operation panel.

According to the configuration shown in FIG. 4, the volume when the power is turned on is determined by the open/closed states of the switches _7-1 to _7-5 , and the volume in normal times can be adjusted to any value using the pushbutton switches 3 and 4. By pressing the push button switches _17-1 , _17-2 , and _17-3 , the volume can be instantly changed to zero, medium volume, and high volume, respectively.

In the embodiments and modifications described above, an up-down type binary counter capable of data presetting is used as the counter 1, but this counter 1 is an up-down type BCD capable of data presetting of BCD code input/output. Of course, it is also possible to use counters in various counting formats, such as counters.

As is clear from the above description, the volume adjustment circuit according to the present invention includes a counter that presets data when a load signal is supplied, and amplifies the input signal with a gain according to the count data output by this counter. a variable gain amplifier circuit that outputs a variable gain amplifier circuit, and supplies a load signal to the counter when the power is turned on;
a first time constant circuit that stops supplying the load signal after a time period corresponding to a time constant; and a time constant that outputs a first drive signal when the power is turned on, the time constant being larger than the time constant of the first time constant circuit. a second time constant circuit that stops outputting the first drive signal after a time period corresponding to the time has elapsed; and a first preset data output that outputs first data to the counter when the first drive signal is supplied. a preset switch means for supplying the load signal to the counter and outputting a second drive signal when the preset switch is operated; Since it is equipped with a second preset data output circuit that outputs the second data, the desired volume can be automatically obtained when the power is turned on, and even during normal operation, the volume can be increased suddenly and immediately. It becomes possible to change. Further, the volume adjustment circuit according to the present invention, when the power is turned on,
Since the desired volume can be obtained automatically, it is convenient to use in a timer device or alarm device, etc. Also, since the volume can be changed suddenly and instantly, it can be used, for example, to reduce the volume when a visitor arrives or when there is a phone call. It is extremely effective when used for Furthermore, by operating the preset switch when the power is turned on, the volume can be set to the second preset data from the beginning, so even if the volume according to the first preset data is not appropriate, you can immediately respond. Can be done. Furthermore, since the time constant of the second time constant circuit is set longer than the time constant of the first time constant circuit, the first preset data is output for a longer time than the load signal output time when the power is turned on. This ensures that the first preset data is being output even at the timing when the load signal stops, providing the advantage that the first preset data is reliably loaded.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a circuit diagram showing a first modification of the same embodiment, and FIG. 3 is an example of the arrangement of push button switches in the same modification. 4 are diagrams showing a second modification of the embodiment, and FIG. 5 is a diagram showing an example of the arrangement of push button switches in the modification. 1...Counter (up-down counter), 6...
First preset circuit, 15... Second preset circuit, 17... Preset switch, 21... Variable gain amplifier circuit.

Claims (1)

[Scope of Claims] 1. A counter that presets data when a load signal is supplied, a variable gain amplifier circuit that amplifies and outputs an input signal with a gain according to count data output by the counter, and when the power is turned on. a first time constant circuit that supplies a load signal to the counter and stops supplying the load signal after a time period corresponding to a time constant; a second time constant circuit that stops outputting the first drive signal after a time period corresponding to a time constant greater than a time constant of the circuit; a first preset data output circuit that outputs a preset data output circuit; a preset switch means that supplies the load signal to the counter and outputs a second drive signal when the preset switch is operated; A volume adjustment circuit comprising: a second preset data output circuit that outputs second data to the counter when a signal is supplied.