JPS5838692Y2 - Shyan Regyure Tatsuki O-Day Out Cairo - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an audio output circuit with a shunt regulator for a television receiver that does not cause the screen to move even when the volume knob is turned quickly or when a large audio signal is input, and consumes less power.

Conventionally, audio output I for audio on a television receiver
The C circuit had the following drawbacks.

In other words, when the audio signal becomes large, the power consumed by the IC circuit and the speaker increases, causing a large amount of current to flow.On the other hand, when the audio signal is small, the amount of current decreases, and this current change causes flyback. This will adversely affect other circuits through the transformer.

This adverse effect is particularly noticeable in the vertical circuit; when the audio becomes louder or softer, the change appears in the vertical circuit, causing the screen to twitch.

In order to overcome this drawback, an audio IC circuit has been devised in which a shunt regulator circuit 1 (hereinafter referred to as S and R circuits) is added to the audio IC circuit, as shown in FIG.

The basic function of this S-R circuit 1 is that when the current consumption in the audio out circuit 2 is large, the current C consumed in the S and R circuits 1 is small, and the current consumption B in the audio out circuit 2 is small. When it is low, the current C consumed by S and R circuits 1
Adjustments are made so that the total current A consumed by the IC circuit is always constant when viewed from the power supply S side by increasing
(See Figure 2).

In FIG. 1, 3 indicates a speaker, and F, B, and T indicate a flyback transformer.

However, when this S, R circuit 1 is added, as is clear from FIG. 2, there is a drawback that since a constant current is always flowing, the amount of current is large, and therefore the power consumption is also large.

A proposal as shown in FIG. 3 has been made in order to improve the drawback of causing such large power consumption.

In other words, in the block diagram of FIG. 3, when the volume knob of the volume control circuit 4 is set in the direction of low sound, the total current becomes small, and when the volume control circuit 4 is set in the direction of high sound, the total current becomes large. Adjust the shunt regulator bias supply circuit 5 to adjust the currents in the S and R circuits 1, and turn the volume knob to change the total current as shown in Figure 4, keeping the volume knob fixed. A constant current is always flowing, and when the volume knob is turned in a direction that reduces the sound, the total current is reduced and power consumption is reduced.

However, this circuit also has the drawback that when the volume knob is rotated quickly, the total current changes accordingly, which adversely affects the vertical circuit and the like, causing the screen to move.

The present invention solves the above-mentioned drawbacks of the conventional circuit, and will be described in detail below with reference to the drawings.

The present invention is characterized in that a filter 6 is inserted before the S and R circuits 1, as shown in FIG.

In FIG. 5, when the volume knob is suddenly turned, the outputs of the S and R bias supply circuits 5 change suddenly, as in the case of FIG. 3.

This sudden change in bias voltage is applied directly to the S and R circuits 1.
If the total current is added to , the total current will also change rapidly and the screen will move.

However, in the present invention shown in FIG.
Adjust the bias voltage supplied to S and R so that it changes at an appropriate speed when you turn the volume knob quickly.
In addition to circuit 1, the time constant of filter 6 is determined so that the total current changes in an optimal state, so the total current can be changed relatively slowly, so the screen moves like a conventional one. There is no such thing.

FIG. 6 shows an example of a specific circuit of the present invention.

In FIG. 6, the voltage appearing on the volume knob R1 is the voltage appearing on the transistor Tr1. The signal is divided by resistors R2 and R3 and resistors R4 and R5 through a buffer consisting of Tr2, and then supplied to the volume control circuit 4 and the shunt regulator bias supply circuit 5.

This S, R bias supply circuit 5 is made up of a transistor Tr3 and resistors R6 and R7, and the collector voltage of the transistor Tr3 is high when the volume knob is set to a low volume, and low when the volume is high.

Now, assuming that the collector voltage of the transistor Tr3 is constant, when the current consumption in the audio out circuit 2 is large, the terminal voltage appearing on the resistor R8 of the S, R circuit 1 becomes large, and the emitter voltage of the PNP transistor Tr4 decreases. However, since the base voltage of the transistor Tr4 and therefore the collector voltage of the 1-transistor Tr3 are constant, the transistor Tr4 is in the cut-off direction, and the transistor T
The collector current of r4 and hence the base current of transistor Tr5 stop flowing, transistor Tr5 is also cut off, transistor Tr6 is also cut off, and no current flows through S and R circuits 1.

Conversely, when the current consumption during auto-out is small, the terminal voltage appearing on resistor R8 becomes small, and transistor Tr4. Tr5. Tr6 is turned on, and a constant current always flows through the S and R circuits 1.

Next, the transistor Tr3 of the S, R bias supply circuit 5
When the collector voltage of the transistor T changes, that is, when the volume knob is turned to decrease the volume, the transistor T
The collector voltage of r3, that is, the base voltage of transistor Tr4 becomes high, the current flowing through S and R circuits 1 decreases, and when the volume knob is turned toward the loudest direction, the base voltage of transistor Tr4 becomes low, and S ,
The current flowing through the R circuit increases, resulting in the characteristics shown in FIG.

Next, the filter 6, which is a feature of the present invention, will be explained in detail.

This filter 6 includes a capacitor C that applies a bias voltage (E, ) to the collector of the transistor Tr3 of the S, R bias supply circuit 5, and a collector resistor R7. The rapid change in voltage appearing at the base of the circuit is made into a slow voltage change by the time constant of these resistor R7 and capacitor C.

This slow voltage change directly changes the current in the S and R circuits 1 and does not have any adverse effect on the screen.

Now, let El be the collector voltage of transistor Tr3 when the volume knob is maximized, let Eo be the DC voltage applied to the negative side of capacitor C at this time, and let El be the collector voltage of transistor Tr3.
and E.

Set the voltage to a slightly higher voltage.

When the switch is turned on with the volume knob set to maximum, the potential on the positive side of capacitor C becomes E.

, current immediately flows through the S and R circuits 1, and the collector voltage of the transistor Tr3 becomes El in the time determined by the time constant of the capacitor C and the resistor R7, but E and El
Since the voltage difference between is small, the collector voltage is E.

Even if this happens, too much current will not flow through the S and R circuits 1.

By applying a bias voltage to the capacitor of the filter 6 in this way, when the switch is turned on, the screen does not move due to changes in the sound, and furthermore, a large amount of current does not flow.

Next, we will discuss the case where the capacitor is not biased.

If the capacitor C is grounded to the earth side, the collector potential of the transistor Tr3 becomes Qv when the switch is turned on, and a large amount of current flows through the S and R circuit 1, which may destroy the transistor Tr6.

Furthermore, when C is connected to the power supply side, when the switch is turned on, the collector potential of the transistor Tr3 becomes the same voltage as the power supply, the S and R circuits 1 are turned off, and as the capacitor C charges, the collector voltage of the transistor Sr3 becomes It descends and goes through the S and R circuits for 1 minute.

This time is related to capacitor C and resistor R7, so
It takes a while, and if you turn up the volume knob and hear loud audio, the screen will shake.

The present invention can eliminate the above-mentioned drawbacks and can also be expected to have the following effects.

(1) Volume Since the volume knob is turned quickly by hand, the screen will move if the time constant of the filter is not large enough.The time constant of this filter is determined by resistor R7 and capacitor C, the resistance value of R7. If C is sufficiently large and, for example, 10kQ, the capacitance of capacitor C is 47μF.
There is almost no cost increase due to the insertion of the capacitor.

(2) Since the terminal voltage across the resistor R8 of the S, R circuit 1 is used as the comparison voltage of the S, R circuit, both ends of the resistor R8 are connected to the pins of the IC, as shown in Figure 6. Even if the capacitor C is inserted in this way, there is no burden on the number of pins, and by appropriately changing the capacitance of the capacitor C, the time constant can be changed as appropriate.

(3) Volume When turning the volume knob quickly,
It is completely unsuitable to insert a filter (teeth coupling) into the power supply line.

This is because, as mentioned above, a time constant of Q, about 5 seconds is effective, so it is necessary to increase the capacitor or resistance of the filter, but if a resistor is inserted into the power supply line, the current flowing through it is large, so the voltage drop will be large. Since it becomes too large, we have no choice but to make the capacitor larger.

Now, if the resistance is 10Ω, the time constant Q is 5 seconds, the capacitor has an extremely large capacity of 50,000 μF, and is no longer practical.

According to the present invention, there is no need to use such a large capacity, and there is no power supply voltage drop.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional S, R circuit type audio out, and FIG. 2 shows the audio output current and S for the audio output in the block diagram of FIG. A diagram showing the relationship between the R circuit current and the total current, Figure 3 is a saving type S, R circuit block and lock diagram that changes the bias voltage of the S and R circuits according to the volume knob, and Figure 4 is a block diagram of Figure 3. Figure 5 is a block diagram of the present invention in which a filter circuit is inserted into the S and R bias supply circuits. FIG. 6 is a diagram showing an example of a specific circuit of the present invention. 1... Shunt regulator (S, R), 2.
... Audio output circuit, 3 ... Speaker, 4 ... Volume control circuit, 5 ...
...Shunt regulator bias supply circuit, 6.
·····filter.

Claims (1)

[Claims for Utility Model Registration] An audio output circuit and a shunt regulator circuit to which a power supply voltage is supplied from a flyback transformer, a volume control circuit equipped with a volume knob, and a volume control circuit that uses the voltage from the volume control circuit as a human power source. The shunt regulator is configured so that when the knob is turned in a direction that produces less sound, the total current that flows through the audio output circuit and the shunt regulator circuit becomes smaller, and when the volume knob is turned in a direction that produces more sound, the total current that flows through the audio out circuit and the shunt regulator circuit becomes larger. Equipped with a shunt regulator bias supply circuit that controls the circuit,
This shunt regulator bias supply circuit has a filter circuit on the output side consisting of a capacitor and a resistor to which a bias voltage is applied, and the bias voltage is supplied to the shunt regulator circuit through this filter circuit. Auto output circuit.