JPS5814083B2 - voltage control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a voltage control circuit, and is applicable to a volume adjustment circuit of a television receiver, etc., in which the gain of a voltage-controlled amplifier circuit is controlled by a DC control voltage to adjust the volume. It is an object of the present invention to provide a voltage control circuit in which two systems of control means are provided as means for generating control voltages for controlling this amplifier circuit, and each system can be controlled independently.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a pulse generator, and in FIGS.
A pulse with a constant period as shown in the figure is generated and applied to the amplitude limiting circuit 2.

The pulse width of the output pulse from the pulse generator 1 can be changed by the pulse width control circuit 5 of the first control system by moving the trailing edge of the pulse back and forth as shown in FIG.

Further, the output of the amplitude limiting circuit 2 can change the amplitude of the pulse as shown in FIG. 3 by the pulse amplitude control circuit 6 of the second control system.

The output of the amplitude modulation circuit 2 is smoothed by the filter circuit 3, so that when the pulse width is wide or the pulse amplitude is large, it becomes a high DC voltage value as shown in FIG. 4a,
When the pulse width or pulse amplitude is medium, the DC voltage value is as shown in FIG. 4B, and when the pulse width is narrow or the pulse amplitude is small, the DC voltage value is low as shown in FIG. 4C.

The controlled circuit 4 can be controlled by the output of the filter circuit 3, and can be controlled by two control systems.

Next, an example in which this control system is used in a volume adjustment circuit of a television receiver will be explained.

In Fig. 5, 7 and 8 are normally open push buttons connected in series between the power supply and ground, and are used so that when push button 7 is pressed, the volume increases, and when push button 8 is pressed, the volume decreases. .

When the push button 7 is pressed, the MOSFET 11 is connected to the power supply voltage VCC with the time constant set by the resistor 9 and capacitor 10.
The gate potential rises, and a DC voltage corresponding to the gate potential appears at the source.

On the other hand, when the push button 8 is pressed, the charge in the capacitor 10 flows toward the ground, reducing the DC voltage of the source.

The capacitor 10 used has a low leakage current,
Furthermore, if the parts surrounded by the dashed-dotted lines are sealed together with a high-resistance resin, the charge stored in the capacitor 10 will be retained without being discharged even after the power switch is turned off, and the DC voltage corresponding to the charge will be It is something that will be remembered.

Such composite devices are commercially available as analog memories.

The source of the MOSFET 11 is connected to the collector of a transistor 14 via a resistor 13.

12 is a source resistance.

15 is a transmitter of the remote control device, and when a remote control signal for changing the volume is emitted from this transmitter 15,
Receiver 16 of a remote control device installed in a television receiver
By receiving this remote control signal, the pulse width of the output pulse of the pulse generator 17 can be widened or narrowed.

That is, the pulse generator 17 is composed of a microcomputer, and when the power is turned on, the pulse generator 17 has a duty ratio of 50:5, for example.
It is preprogrammed so that a zero pulse appears at the output.

When a signal to increase the volume is emitted from the transmitter 15, the output of the counter in the pulse generator 17 increases sequentially while the transmission continues, and the pulse width of the output pulse is determined based on the output of this counter. It is something that expands.

When the volume is to be reduced, the operation is the opposite of the above.

The output pulse of the pulse generator 17 is applied to the base of the transistor 190 via the resistor 18 and amplified.

A power supply voltage VCC is applied to the collector of the transistor 19 via a resistor 20.

The output pulse of the pulse generator 17 is transmitted to the transistor 19.
Since the polarity is reversed, the signal is applied to the base of the transistor 14 via the resistor 21, and the polarity is reversed again and amplified.

The output pulse appearing at the collector of the transistor 14 is converted into a DC voltage by a filter circuit consisting of a resistor 22 and a capacitor 23, which controls the volume control circuit 24 and outputs the speaker 2.
Adjust the volume of the sound emitted from 5.

That is, the push button 7 provided on the television receiver body,
8 or by operating the transmitter 15 of the remote control device, the volume can be adjusted independently.

To explain the actual operation, when the television receiver is turned on for viewing, the pulse generator 17 generates a pulse output with a duty of 50:50, while the capacitor 1
0, an electric charge proportional to the volume of the previous viewing is stored, so the output pulse of the pulse generator 17 is generated by the transistor 14, and its peak amplitude is based on the electric charge of the capacitor 10. is suppressed by the source voltage of capacitor 1, smoothed by the filter circuit,
The volume control circuit 24 uses a DC voltage proportional to the amount of charged charge of 0.
is controlled, and sound is emitted from the speaker 25.

When the push button 7 is pressed in this state, the voltage charged in the capacitor 10 increases, and the sound becomes louder.When the push button 7 is stopped, the volume stops increasing.

On the other hand, when the push button 8 is pressed, the charge in the capacitor 10 is discharged, so the voltage becomes low, and the sound decreases accordingly.When the push button 8 is stopped, the decrease in volume stops.

In this way, the volume can be freely adjusted by simply pressing the two push buttons 7 and 8 on the television receiver main body side.

In addition, the discharged charge in the capacitor 10 is not discharged and is retained for a long time even after the television receiver is turned off, so the sound can be heard at the original volume even when the power is turned on again. It is.

On the other hand, when adjusting the volume using a remote control device, the transmitter 15 can change the duty of the pulse generated from the pulse generator 17, and the width of the pulse applied to the base of the transistor 14 can be changed to adjust the volume. Can change.

In this case, if the duty of the output pulse of the pulse generator is set to 50 when not remotely controlled, the width of the pulse generator's output pulse can be increased up to twice by remotely controlling it, so the width of the output pulse of the pulse generator can be increased up to twice as much by using push buttons 7 and 8. You can increase the volume up to twice the volume.

The waveform shown in FIG. 6 shows a state in which the amplitude of the pulse is changed by the push buttons 7 and 8, and can be controlled approximately from VCC (power supply voltage) to O.

After smoothing this waveform, the DC control voltage is 0-VCC/2
It is variable within the range of .

In Figure 7, the output voltage of MOSFET 11 is set to V by pressing buttons 7 and 8.
The DC control voltage after smoothing this waveform, which shows the variable range due to the pulse width change of the remote control device when the voltage is set to s, is variable within the range of 0-Vs.

Television receivers with a push-button volume adjustment function that have recently appeared on the market use a method that changes only the pulse duty, and do not have a volume memory function when the power is turned off, and when the power is turned off again. The volume when it is turned on is a pulse with a duty set in advance at the manufacturing factory, and the volume is relatively low, so the disadvantage is that the viewer has to raise the volume to his or her preference. Since the invented device memorizes the volume, this drawback is overcome and the device becomes easier to use.

As described above, according to the present invention, when using a pulse generator that can freely change the pulse width, it is possible to create a control voltage with both pulse amplitude and pulse width, and to control volume, etc. It is used to produce a dog-like effect.

Also, the voltage value determined by the control of a pair of switches is M
Since it can be maintained by an OS transistor and a capacitor, the same voltage can be generated the next time the power is turned on, and it is also possible to obtain a voltage greater than the voltage maintained by the capacitor and MOS transistor by remote control. be.

In the above embodiment, the present invention is limited to the volume adjustment circuit of a television receiver, but the present invention is not limited thereto, and can be used for various adjustments such as color saturation and hue.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a voltage control circuit according to an embodiment of the present invention, FIGS. 2, 3, and 4 are operational waveform diagrams of the same circuit, FIG. 5 is a specific circuit diagram of the same circuit, and FIG. 7 are operational waveform diagrams of the same circuit. DESCRIPTION OF SYMBOLS 1... Pulse generator, 2... Amplitude limiting circuit, 3... Filter circuit, 4... Controlled circuit, 5... Pulse width control circuit, 6... Pulse amplitude control circuit, 9... Resistor, 10... …
Capacitor, 15... Transmitter, 16... Receiver, 17...
...Pulse generator.

Claims (1)

[Claims] I MOS} A capacitor is connected between the gate of the transistor and the ground, and a resistor is connected between the gate and one terminal of each of the pair of switches, and the capacitor and the resistor constitute a charge/discharge circuit, and the The other end of one of the switches is grounded, the other end of the other switch is connected to a DC power supply terminal, the source of the MOS transistor is grounded through a resistor, and the collector of the transistor is connected through the resistor. A pulse generator is connected to the transistor, and a pulse from a pulse generator is applied to the pace of this transistor, and the pulse from the collector of the transistor is converted to DC and applied to the controlled circuit, and the pulse width of the output pulse of the pulse generator is controlled by a remote control device. A voltage control circuit characterized in that the voltage is changed by a remote control signal sent from a transmitter.