JPS581382A - Detector for television signal - Google Patents

Abstract

PURPOSE:To detect a television signal, which is not influenced by noise, even in a weak electric field, by removing noise components contained in the television signal through an AND gate circuit and a resonating circuit. CONSTITUTION:When the intensity of an electric field is low, a horizontal synchronizing signal has small amplitude and a waveform containing noise. Therefore, a horizontal synchronizing signal which contains the noise only during some period of a flyback pulse is led out of an AND gate circuit 22. This signal is passed through a resonating circuit 5 to remove only the noise component coincident with the resonance frequency of the horizontal synchronizing signal frequency component. This output voltage becomes higher than the voltage of a constant-voltage power source 16 by adequately selecting the voltage of the power source 16, so a transistor 14 turns off, so that an audio signal is transferred normally without being muted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting an automatic television signal, which is used, for example, to mute the sound of a television receiver.

Nishi Vichi 1”lN fly system (1? Published in 1979: Official Gazette Ugly 4)
According to the above, if a television receiver receives a signal other than the television signal, a mechanism is required to clean the audio circuit so that the signal does not interfere with the television signal. It is a fairy tale that something is mandatory, and this invention corresponds to this regulation.

As a means to comply with the above regulations, it is possible to detect the presence or absence of reception of a television signal by detecting the horizontal synchronization signal with a beater.
However, with this method, the horizontal synchronization signal contains a large amount of noise when the electric field is weak, so if this is detected, the detection ratio will be poor, and for example, this detection port f will activate the 1st step of the sound sound. If the cylinder is closed, malfunction may occur.

This O-origin was made in consideration of the above-mentioned circumstances, and it can be used to ensure the presence or absence of a signal even in a weak electric field.
Another object of the present invention is to provide a separate and highly accurate television signal detection device.

Hereinafter, in allftlg in which an embodiment of the present invention will be explained according to the drawings, @ is a tended gate circuit.
This diode (1), (the input terminal of the phantom KAN-V, fp4wc, is the flybatter pulse from the flybatter pulse (not shown) and the horizontal synchronization signal from the Hiraoka J11 circuit (not shown). is input 5.

One of the diodes (1) and (common to both) is connected to the power supply through a resistor (3), and the other is connected to a capacitor through a resistor (4). Since it is from (6) and coil (7), it is common! Connect to Ii circuit (6). This parallel resonant circuit (6) functions as a one-pass filter that passes only the shoulder wave number corresponding to the pulse width of the horizontal same-layer signal. (9
) is connected to the above m circuit (currently) through the resistor (8), and this circuit (@ is the IF iris transistor (to), the capacitor (b), the resistor (b), (to) The base of the upper ε transistor # (to) is resistance Kc.
@, collector # is the power supply, and emitter is ground and resistor (b).

– are connected to each other. This beater detection circuit (9
) receives the signal from the above m circuit and outputs a detection signal having a signal level corresponding to the beater value of the signal passed through the filter. o4 is a driving current transistor located above the output from the upper ε beater detection circuit (9),
Colleta # is the audio amplification circuit (2) of the television receiver.
) and the audio output circuit -, the knob A that performs audio output *ors* with the output from the transistor #- is a resistor -
- is the constant voltage number n, m is the condenser of the eyebrows that prevent direct combing) is for subio.
a, sxaw (4) No L (stations must not receive television signals with strong electric fields) - 1st W ((transition) LAL (II) must not receive signals other than television signals L''Cvz
When it was 11, %@411 (萄いしく6) indicated that it had received a TV signal from -Denden.

At the same time, the two input terminals 4HtIc of the tended gate 4HtIc in the state of lI2 [11 (4) 17% self) are shown in (4) and (2). The fly batter pulse and the horizontal W4Mm'4 are filled as shown in the figure, respectively.
The resistance (the output of the ship is F1) is the resistance of both channels #M and 2. By selectively extracting the wave number component corresponding to the pulse width of the horizontal positive signal, this output waveform is shown in Figure 112).This output waveform is detected by the beater detection circuit (@) as no b a@
Since the DC voltage corresponding to FEt is extracted, the signal of IllgJ (9) in the above beater detection circuit (-)e is positive n beater value and becomes transistor #) is turned ON, and the capacitor! (b) is charged to a positive beater value in a short period of time, and the input message to the base of transistor #- is less than the positive beater value, and the beater value of Jiai and Emitsu #Hiromasa is maintained for Vh. , transistor base, engineering ivy rtsc
# is biased and Shiranjis # (to) is cut off. The electric charge accumulated in the amount of condensation (b) is the resistance -
, discharges at a long time** through the trout. As a result, the output waveform shown in at diagram (2) is obtained, and this output voltage is JP
summer! If the emitter voltage of the transistor (transistor) is very high, that is, if it is higher than the potential of the power supply indicated by the broken line of Jl, the output of the audio amplifier circuit (b) will be 01v. The voice message is not affected by Rungis # (b) and is normally transmitted to the next stage audio output circuit.Next, to explain the case of L (1) without INI diagram (A), In this case, the TV receiver is receiving the TV signal amount &-, so there is no horizontal V4N signal, but only noise as shown in the figure below. The output of the circuit 1 is full of noise due to one of the seven driver pulses, as shown in Part 1 (G). This noise is common! ! till(5) vc
Since all the noise except the one that matches the resonance shoulder wave number is removed, the output from the common 1m path (IS) is ll5FIi.
(9) As shown by K, it becomes zero. Therefore, the output of the beater detection circuit (9) 112Ii1 (as shown by Ifl, becomes almost zero. This voltage is sufficiently lower than the voltage of the constant voltage power supply Q4n shown by the broken line, and the output voltage is oM). The audio output signal f of the audio amplification circuit (b) is generated using a low impedance constant voltage 1 using the collector of the transistor (b).
i111I), the sound is not transmitted to the next stage audio output circuit 64 for 1 km, and the sound is muted and one f'
IC, Figure 44 (4) to 44) To calculate the case of 0 weak electric field strength. As shown in Jinnotoji 114g (2) (
%The horizontal synchronization signal has a small amplitude and is a wave containing noise, so the AND gate is used as a signal.
0) As shown in K, horizontal synchronization messages containing this noise can be extracted only during the &i period of the 7 driver pulses. This signal is a horizontal synchronizing signal fJ
This voltage waveform is 1!4g (denoted by II) in order to extract only the noise components that do not match the ms wave number in the il wave differential modification.

This output voltage will be higher than the voltage of the physical distribution power supply (b), so the transistor #(b) will be 011, and the audio signal will not be transmitted. , positive N.

That is, in the above-mentioned IC, as a means for detecting television broadcast signals, horizontal 1
By extracting the i1Jl11 signal and inputting it and the flybatter pulse to an AND gate circuit, 1 minute of noise in the '&- period of the flybatter pulse is removed.
8M improvement measures are carried out.Next, by moving the resonance circuit that resonates with the shoulder waves of the horizontal synchronization signal and the flybatter pulse, and by fighting the horizontal synchronization signal, eliminating all waves other than the wk component of L1 and L2. The 8th summer resonator was held. By removing the noise components contained in the television signal using the AND gauge circuit layer and the resonance circuit layer,
Even in a weak electric field, the television signal can be reliably detected without being affected by noise, and the audio output circuit 61In can be operated accurately using this signal. Audio fi of TV subscription machine
l f I would like to explain the application of automatic tuning uis.
It is also possible to apply VC such as the Diffie circuit of IT, and obtain the same effect as in the above embodiment.As described above, this generation @
According to the company, it is possible to provide a high-precision TV 124 detection device that can reliably determine whether the TV signal is ON or not, even in the world of 1ill and 11 in the world of television broadcasting. .

[Brief explanation of the drawing]

The first circuit layer is a circuit layer showing a television signal detection device according to an embodiment of the present invention, and 81281 to 411 are waves fiI#j! for explaining the operation of this embodiment. In J, SII (4) or tightening means that the television signal with a strong electric field cannot be received, and MS diagram (4) or 5L (6) means that it cannot receive a signal other than the television signal. When you are not
1141]! I(4) to (to)) indicates that the bird has received a weak electric field television signal. (6)...vmma filter, (9) -detection circuit, -
...And gate circuit. Agent Bankai Shin - (1 other person) Figure 2 0 -11111111---Figure 3
Chest 4

Claims (1)

[Claims] (1) Horizontal synchronization signal f @ Inputs the horizontal synchronization signal from the circuit and the 7-Lybatter pulse signal from the 7-Lybatter transformer. A band-pass filter that passes only the waste correspondence corresponding to the pulse @C of the synchronization signal; and 1) The band-pass filter circuit has a signal level corresponding to the beater value of the filter-transmitted signal in response to the amount of overconfidence passed through the filter of this band-pass filter circuit. A television signal detection device comprising a detection circuit that outputs a detection signal.