JPH0364282A - Automatic detecting circuit for end of tv broadcast - Google Patents

Abstract

PURPOSE:To automatically detect a fact that a TV broadcast is ended and to disconnect a power source of a TV receiver by providing three detecting circuits and a power source switch control circuit. CONSTITUTION:In a detecting circuit 2, amplitude of a VIE input becomes about '0', a higher voltage than the time of TV broadcast is outputted from an IFAGC circuit 3, and it is discriminated by a comparator 4. In a detecting circuit 5, whether a synchronizing signal is contained in a video signal or not is discriminated by locking and integrating the synchronizing signal by an AFC loop 6. A detecting circuit 11 discriminates whether an inputted signal is a video signal or only a noise by inputting a Y signal to a differential amplifier 13 together with a signal delayed by one horizontal period and checking the correlation. Subsequently, three detecting signal voltages are inputted to a power source switch control circuit 6, and only when the signal is continued for several minutes, a power source of a TV receiver is turned off. In such a way, by detecting automatically a fact that the TV broadcast is ended, the power source of the TV receiver can be turned off.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a TV receiver, and more particularly to a circuit for automatically turning off the power of a TV receiver.

[Conventional technology]

Conventional devices that automatically turn off the power of TV receivers include devices that use an OFF timer. Most of these devices allow you to set the time to turn off the power or the number of hours from now to turn off the power. ), the power is automatically turned off at a predetermined time. [Problem to be solved by the invention] One way to use the OFF timer is to turn off the TV receiver when a TV broadcast ends late at night. There is a way to turn off the power. However, the OFF timer has the trouble of having to set the time and time in advance. Keita, sight 11! ! Sometimes people forget to set the OFF timer and fall asleep for a while, leaving the TV receiver on all the time.

This invention was made to solve the above-mentioned problems, and it automatically detects the end of TV broadcasting.
The purpose is to obtain a circuit that turns off the power of a V receiver.

[Means to solve the problem]

The TV broadcast end automatic detection circuit according to the present invention includes a detection circuit that detects that the interpupillary distance of an input signal is much smaller than normal, and a detection circuit that detects that the input signal does not include a synchronization signal. , a detection circuit that detects that the input signal does not contain a video signal but only noise, and these three
The system is equipped with a power switch control circuit that determines when two detection circuits simultaneously satisfy the conditions and output a detection signal and this continues for several minutes and turns off the AM of the TV receiver.

[Effect]

The three detection circuits and power switch control circuit according to the present invention turn off the power of the TV receiver based on signals from the three detection circuits that detect when TV broadcasting ends.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, a video signal converted to an intermediate frequency is input to the input terminal il+. The detection circuit (2) determines that the amplitude of the input VIF has become very small compared to normal T''/broadcasting.When TV broadcasting is being performed, the d IFAGC circuit (3) Outputs the voltage. However, when the TV broadcast ends, the amplitude of the VIF input becomes #'
When t'r o is reached, H is output from the I FAGC circuit (3).
High voltage is output during TVTV broadcasting.

A comparator (4) determines this and outputs a signal voltage indicating that the end of the TV broadcast has been completely detected.

Next, the detection port v! A video signal detected and gain-controlled by the detection circuit (2) is input to rt51.

In the detection step (5), it is determined whether or not the video signal includes a synchronization signal. During normal 'r/broadcasting, the Kfl synchronization signal is locked in the AFC loop (6) and multiplier (7)
A certain voltage is output from the integrator (8) through the integrator (8).

However, at the end of the TV broadcast, only noise is input to the detection circuit (5) and there is no synchronizing signal, so the output voltage of the integrator (8) becomes smaller than during the TV broadcast. This is determined by a comparator (9), and a detection signal voltage is outputted through an inverter (1o).

Next, the video signal output from the detection circuit (2) is also input to the detection circuit (11). Detection circuit (II) ld
Determine whether the input signal is a video signal or only noise. The input video signal is Y/C separated by a Y/C separation circuit (!no), and a Y signal is output.

This signal is input to the differential amplifier 0 together with a signal delayed by one horizontal period. During normal TV broadcasting, there is a line correlation in the scanning lines, so the output pupil width of the differential amplifier becomes very small, and as a result, the output voltage of the integrator Q4 becomes small. However, After the TV broadcast ends, the detection circuit (21 gain-controlled noise with a large interpupillary distance is output. Since the noise has no line correlation, the integrator α4) outputs a higher voltage than during the TV broadcast. This is determined by the comparator (15) and the detection signal [BE
' is output.

When the TV broadcast ends, the three detection circuits +2j (f
A detection signal is output from i(11). These three signal voltages are input to the WL# switch control circuit (6), and A
The signal is input to the microcomputer 0 through the entire ND circuit. When the microcomputer α receives a detection signal indicating that the TV broadcast has ended, it activates a timer and outputs a power switch control signal only when the detection signal continues for several minutes to turn on the TV receiver. Turn off the power.

Also, if you set the tuner on your TV receiver to an empty channel, the situation will be the same as if the TV broadcast had ended.

However, in reality, it takes about several seconds to tune to an empty channel, and the setting time of the timer (I9) is set long so as not to malfunction when tuning to an empty channel.

In addition, although the above embodiment includes three detection circuits, this is to increase the reliability of the operation, and the same operation can be performed even if there are one or two detection circuits. I can do it. Therefore, if the end of TV broadcasting can be reliably detected even with one detection circuit, only one detection circuit is sufficient and costs can be reduced.

Furthermore, in the above embodiment, the detection circuit (2) for determining whether the amplitude of the input signal has become small can be applied not only to TV broadcasting but also to radio, radio, etc.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to automatically detect the end of TV broadcasting and turn off the power of the TV receiver, so it can be used in the same way as an OFF timer, and can also be used like an OFF timer. There is no need to worry about setting the time and time, and there is also the advantage of saving on electricity bills since there is no need to turn on the TV receiver even after the TV broadcast has finished.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an automatic TV broadcast end detection circuit according to an embodiment of the present invention. Referring to the figure, (1) is the input terminal, [21f5] f is the detection circuit, (3) is the IFAGC circuit, 141t9
+05) is a comparator, (6) is an AFC loop, (7) is a multiplier, (8) α4 is an integrator, (+01 is an inverter,
0 is a Y/C separation circuit, 03 is a differential amplifier, 00 is a power switch control circuit, 0 or an AND circuit, (I8) is a microcomputer, and Q (to) is a timer. 1

Claims (1)

[Claims] In a TV receiver, a detection circuit detects that the amplitude of an input signal is much smaller than normal; a detection circuit detects that the input signal does not include a synchronization signal;
A detection circuit detects that the input signal does not contain a video signal and is only noise, and the above three detection circuits simultaneously output a detection signal that satisfies the conditions, and it is determined if this continues for several minutes. An automatic TV broadcast end detection circuit consisting of a power switch control circuit that turns off the power to the TV receiver.