JPS5840701Y2 - Television receiver power control device - Google Patents

Description

[Detailed explanation of the invention] If you fall asleep while watching a TV broadcast late at night, the receiver will not turn on even though the TV broadcast has ended, which is very dangerous. I don't like it from above either.

Taking these points into consideration, power control devices are known that turn off the power to the receiver immediately after a broadcast ends.

That is, this power supply control device detects the absence of broadcast waves, supplies the detection output to a time constant circuit, and turns off the power to the receiver after a predetermined time determined by the time constant circuit.

Usually, the predetermined time is selected so that the power is turned off 10 to 20 seconds after the broadcast ends.

By the way, if the above-mentioned predetermined time is selected to be relatively short, about 10 to 20 seconds, a malfunction such as the power being turned off during UHF channel selection may occur.

That is, in general, to switch to a UHF channel, VHF
Since the desired station on the UHF channel is selected after switching the knob on the tuner to the UHF channel, this channel selection time takes a relatively long time.

``It usually takes about 30 seconds to 1 minute to achieve an accurate station.

Since television broadcast waves are not completely received during this channel selection period, it is equivalent to a state in which there are no broadcast waves during the channel selection period.

Therefore, if this channel selection time takes several tens of seconds, the above-mentioned power supply control device will operate and turn off the power.

In order to eliminate such defects, the above-mentioned predetermined time period UH
Even in the case of F, it is sufficient to set the predetermined time relatively long, for example, about 19, so as not to malfunction, but it is not preferable to select a long predetermined time in this way because the responsiveness during UHF broadcast reception will deteriorate.

The present invention takes these points into consideration, especially when receiving UHF and V.
By changing the time constant of the above-mentioned time constant circuit when receiving HF, the response is improved regardless of which channel is being received, and the power saving effect is further increased. It is something.

Hereinafter, the power control device for a television receiver according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of a power supply control device according to the present invention.
is a television set, to which operating voltage is supplied from a power supply 2.

A power switch SW1 is interposed on the operating voltage transmission path, and this switch SW1 is controlled depending on the presence or absence of broadcast waves.

3 shows a circuit for controlling this switch SW1,
Assume that this includes, for example, a relay that controls on/off of the switch SW1 and a circuit that controls this relay.

It is assumed that when there is a broadcast wave, the relay is energized and the power switch SW1 is turned on.

The switch control circuit 3 generates a control signal S corresponding to the presence or absence of broadcast waves.

However, in this example, the video output is used together with the audio output to detect the presence or absence of broadcast waves on the reception channel.

Although it is possible to detect the presence or absence of broadcast waves using only one of the outputs, when only one of the outputs is used in this way, the following malfunction may occur.

In other words, when there is no broadcast wave of a channel adjacent to a receiving channel, it is possible to detect the presence or absence of a broadcast wave of that channel simply by detecting the presence or absence of audio output. When a wave exists, the audio output of the adjacent channel is drawn in by the presence of the AFT circuit built into the television set 1.
As a result, even though there is no audio output from the receiving channel, an output is obtained as if there were audio output.

Therefore, the presence or absence of broadcast waves cannot be accurately detected using only this audio output.

Similarly, even when only video is output, a similar malfunction occurs when broadcast waves of the lower adjacent channel are present.

This example is an example in which the presence or absence of a broadcast wave of a receiving channel can be reliably detected even when a broadcast wave of a lower adjacent channel is present, taking such points into consideration.

First, the circuit system for detecting the presence or absence of the audio output SA will be explained, but the presence or absence of the audio output can be determined by detecting the presence or absence of noise.

If a noise component exists, the audio output SA also exists, so the audio output SA in the receiving channel is supplied to the coupling terminal 5, and this audio output SA is supplied to the bypass filter 6 to output the audio. Detect the noise component SN included in .

The noise component SN is supplied to the first comparison circuit 8 through the detection circuit 7.

This first comparator circuit 8 is constituted by an operational amplifier, and a predetermined reference voltage E1 is supplied to its child terminal.

Therefore, the first comparison output SH1 is obtained only when the audio output SA is not present.

On the other hand, the video output Sv in the reception channel supplied to the terminal 11 is sent to the second comparison circuit 13 via the smoothing circuit 12.
is supplied to

A reference voltage is supplied to a child terminal of the second comparator circuit 13.

The selection of this reference voltage E2 will be explained with reference to FIG.

If we now consider a negative polarity output as shown in FIG. 2 as the video output Sv, when the video output Sv exists, the average level of the video output Sv becomes 1.

However, when there is no video output Sv, that is, when there is no signal, the level becomes level 2, which corresponds to the own level.

However, if there is a broadcast wave on the lower adjacent channel even though there is no video output Sv, the average level of the video output Sv at that time is not the white level ■2 but the sync level ■
It becomes 3.

Therefore, in this example, the reference voltage E2 is set to an intermediate voltage level between (1) and (3).

If the reference voltage E2 is selected in this way, the second comparison circuit 1
The second comparison output SH2 is obtained only when the smoothed output supplied to the reference voltage E2 is lower than the reference voltage E2, that is, when the level of the smoothed output corresponds to the voltages 1 and 2.

In other words, the second comparison output SH2 is obtained only when there is a broadcast wave of the receiving channel, when the broadcast wave of the receiving channel ends, and when there is no broadcast wave of the lower adjacent channel.

The first comparison output SHI mentioned above is obtained when there is no audio output SA, so if this and this second comparison output SH2 are supplied to the AND circuit 15 and the AND output is taken, it is determined that the broadcast wave of the receiving channel is present. AND output S only when

will be obtained. This AND output S.

is the above-mentioned switch control circuit 3 via the time constant circuit 20.
is supplied to

Therefore, AND output S.

As long as is obtained, the relay will continue to be energized,
The power switch SW1 is always on, and power continues to be supplied to the set 1.

However, if there is no broadcast wave of the receiving channel, and even if there is a broadcast wave of the lower adjacent channel, the AND output So cannot be obtained. Control signal S for switch control circuit 3.

As a result, the power switch SW1 is turned off and power is no longer supplied to the television set 1.

Here, in the present invention, the time constant of the time constant circuit 20 is set to UH.
This is changed when receiving the F channel and when receiving the VHF channel.

In this example, in order to speed up the response, the time constant is selected to be about 10 seconds, for example, when receiving a VHF channel, while the time constant is several times longer, about 19 seconds, when receiving a UHF channel. is selected.

In order to realize such a time constant change, the time constant value may be changed when the channel is switched to UHF.

That is, when the time constant circuit 20 is configured with a first capacitor 22a connected in parallel to the resistor 21 as shown in the figure, a second capacitor 22a is connected in parallel to the first capacitor 22a. 22 b, and a control switch SW2 between this second capacitor 22 b and ground.
For example, the switch SW2 may be provided in association with the tuner selection axis so as to be turned on when the channel is switched to UHF.

Therefore, if the channel is changed to UHF, switch SW
2 is turned on, the time constant of the time constant circuit 20 becomes longer, and the time constant is selected to be about 19, for example, as described above.

If the time constant of the time constant circuit 20 is configured to be switched between when receiving a UHF channel and when receiving a VHF channel in this way, when a broadcast ends when receiving a VHF channel, the time constant of the time constant circuit 20 can be changed for 10 seconds from the end point. The power is turned off before and after the broadcast, and on the other hand, when the broadcast ends during UHF reception, the power is turned off about 19 minutes after that point.

Therefore, during the normal channel selection period, even if the channel selection time takes several tens of seconds, the power switch SW1 will not be accidentally turned off.

As explained above, in the present invention, the time constant of the time constant circuit is changed when receiving a VHF channel and when receiving a UHF channel. The power supply will not turn off, and even if the UHF channel broadcast waves disappear, or even if the VHF channel broadcast waves disappear, both will occur after a predetermined period of time. In some cases, the power can be turned off.

Of course, the predetermined time during reception of the VHF channel is extremely short, about 10 seconds, so responsiveness is good and power saving effects can be achieved accordingly.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an example of a power supply control device for a television receiver according to the present invention, and FIG. 2 is a waveform diagram for explaining its operation. 1 is a television set, 2 is a power supply, SWl is a power switch, 3 is a switch control circuit, 20 is a time constant circuit, SA
is an audio output, Sv is a video output, S W2 is a control switch, and 22 a and 22 b are first and second capacitors.

Claims (1)

[Scope of utility model registration request] A power control device for a television receiver that detects the end of broadcasting, supplies the detection output to a time constant circuit, and turns off the power of the television receiver after a predetermined time determined by the time constant circuit. By changing the time constant of the time constant circuit when receiving a VHF channel or a UHF channel, ■ the above-mentioned predetermined time when receiving a UHF channel is made longer than the above-mentioned predetermined time when receiving an HF channel. Power control device for television receivers.