JPS5819171B2 - automatic channel selection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic channel selection device that automatically performs a preset channel selection operation.

In general, in television receivers, tuning is often done by rotating the channel knob, but especially when continuously variable tuning is used, such as when selecting UHF channels, the tuning operation is cumbersome and cumbersome. there were.

Furthermore, in the case of television receivers equipped with touch-type or remote-control type channel selection devices, it is easy to select a single station when changing channels, but preset channel selection operations at the time of initial installation are still cumbersome and inexperienced. It was difficult for amateurs.

The present invention relates to an automatic tuning device designed in view of the above points, and is capable of automating preset tuning operations by sequentially and automatically storing the tuning voltage of each automatically tuned channel. This provides an automatic channel selection device.

In particular, the present invention provides an automatic channel selection device that can accurately receive television signals that arrive mixed with various interference waves and noise, and that does not malfunction due to noise or the like.

Furthermore, the present invention provides an automatic tuning device that can accurately receive and receive signals even in areas where two adjacent channels can be received at the same time and will not malfunction.

In other words, in general, broadcasting station channels are arranged so that adjacent channels are left open and staggered every other channel, but in certain areas it is possible to receive both adjacent channels at the same time. If the automatic channel selection operation is activated, there is a risk of malfunction, and the present invention is an improvement on this point.

The present invention will be described below according to embodiments shown in the drawings.

Figure 1 of the drawings is a block diagram showing an example of a television receiver having an automatic channel selection device.
is the antenna, 2 is the tuner, 3 is the intermediate frequency circuit, 4 is A
FT circuit, 5 is video circuit.

6 is a synchronous separation circuit, 7 is a deflection circuit, 8 is a picture tube,
These constitute a normal television receiver.

Here, these are the start/stop circuit 9. Tuning voltage generation circuit 10. memory circuit 11, signal discrimination circuit 12,
and a noise skip circuit 13 are added to constitute an automatic channel selection device.

When a search start command (automatic tuning command) is given to the start/stop circuit 9 during preset tuning, a search start pulse is generated from the circuit 9 and supplied to the tuning voltage generation circuit 10.

At this time, the tuning voltage generating circuit 10 generates a sweep voltage or staircase voltage that gradually increases or decreases, and this is supplied as a tuning voltage to the tuning diode of the tuner 2 via the memory circuit 11.

Therefore, at this time, the receiving frequency at the tuner 2 is gradually changed.

When the television radio waves of the current channel are received in this way, a television video signal is derived from the intermediate frequency circuit 3, and in conjunction with this, a synchronization signal is derived from the synchronization separation circuit 6 and supplied to the start/stop circuit 9.

On the other hand, the AFT detection output from the AFT circuit 4 is also supplied to the start/stop circuit 9.

Here, especially when a television radio wave is exactly received, the polarity of the AFT detection output voltage changes.

Therefore, this time is detected and a television synchronization signal is derived from the start/stop circuit 91.The synchronization signal is supplied to the noise cap circuit 13, where it is determined whether it is a regular television vertical synchronization signal or noise. It is determined by its level.

! In particular, if this is determined to be a regular vertical synchronization signal, it is applied to the signal discrimination circuit 12 and simultaneously supplied to the tuning voltage generation circuit 10 as a search stop pulse, but on the other hand, it is determined that this is not a synchronization signal but noise. is supplied to the start/stop circuit 9 as a re-search start pulse, thereby repeating the same operation as when the above-described first search start command was given.

Note that here, the vertical synchronization signal obtained from the noise skip circuit 13 also serves as a search stop pulse.

In addition, this noise skip circuit 13 detects whether or not there is a beat frequency signal of 1.5 MHz, which is the difference between the video carrier wave and the audio carrier wave of the adjacent channel, in the video signal obtained from the intermediate frequency circuit 3 at this time. When this beat frequency signal is detected, even if it is determined to be a regular vertical synchronizing signal, a re-search start pulse is derived, which is supplied to the start/stop circuit 9 to restart the search operation.

In this way, the noise skip circuit 13
When no beat frequency signal or noise is detected and a vertical synchronizing signal is derived, this signal is supplied as a search stop pulse to the tuning voltage generating circuit 10.
At 0, the sweep wave (or staircase wave) generation operation is stopped, and from then on, this instantaneous voltage is held and supplied to the tuner 2 via the memory circuit 11 as a tuning voltage.

On the other hand, at this time, the vertical synchronizing signal derived from the start/stop circuit 9 is supplied to a signal discriminating circuit 12, where it is again determined whether or not the signal is a regular television synchronizing signal.

The signal discrimination circuit 12 is disclosed in, for example, Japanese Patent Application No. 52-5152.
No. 8 or Japanese Patent Application No. 52-51531, the number of synchronization signals is counted and whether or not a predetermined number of synchronization signals are present during a certain period of time is used to determine whether the signal is a regular television synchronization signal. When it is determined that this is a regular synchronizing signal, a memory command is derived from the signal discriminating circuit 12, and the command is supplied to the memory circuit 11, whereby the memory circuit 11 receives the signal from the tuning voltage generating circuit 10. The tuning voltage that is applied is memorized.

However, when the pseudo synchronization signal is erroneously derived from the noise skip circuit 13, this signal is detected by the signal discrimination circuit 1.
2, and the circuit 12 generates a re-search start pulse.

This pulse is supplied to the start/stop circuit 9, whereby the same operation as when the above-mentioned first search start command was given is repeated again.

In this way, the same operation is repeated until a true television vertical synchronization signal is derived from the start/stop circuit 9 and the noise skip circuit 13, that is, until correct reception is performed at the tuner 2, and the reception state of a certain channel is accurately achieved. Only then is a memory command issued from the signal discrimination circuit 12, and the tuning voltage at this moment is memorized in the memory circuit 11, and thereafter this memory voltage is supplied from the memory circuit 11 to the tuner 2.

Once the preset tuning operation for a specific channel as described above is performed, if a tuning command is given to this memory circuit 11 by touch or remote control during normal channel selection, the memory circuit 11 will be The memory voltage is supplied to the tuner 2 as a tuning voltage, and this channel is selected and received.

Although only one memory circuit 11 is shown here, similar memory circuits are actually provided for the number of preset stations, and the tuning voltage stored in each memory circuit is used for preset tuning operation (automatic tuning). operations) are sequentially performed by operations similar to those already described.

As described above, according to the automatic tuning device of this embodiment, when a search start command is given during automatic tuning and a search start signal is supplied from the start/stop circuit 9, the tuning voltage generating circuit 10 generates a sweep wave (or Staircase wave) generation operation starts, and the tuning voltage obtained here is applied to memory circuit 1.
1 to the tuner 2, and the receiving frequency is gradually changed.

In this way, when the search stop signal is derived from the noise skip circuit 13 when receiving television radio waves, etc., the sweep wave generation operation of the tuning voltage generation circuit 10 is temporarily stopped.
Thereafter, the tuning voltage supplied to the tuner 2 is held constant for a certain period of time.

During this time, the signal discrimination circuit 12 determines whether the received signal is a legitimate television signal, and confirms that it is a legitimate television signal.
The circuit 11 is supplied with a tuned voltage output circuit 10.
The resulting tuning voltage is stored in the memory circuit 11, and the automatic tuning operation for one station is completed.

On the other hand, when noise is derived from the noise skip circuit 13 or when the signal discrimination circuit 12 discriminates that it is not a regular television signal, a re-search start signal is supplied to the start/stop circuit 9 and the above operation is repeated again. It is done.

In this way, each time the memory operation, that is, the preset tuning operation for one station, is completed in the memory circuit 11°, a search start command is again given to the start/stop circuit 9, and the tuning voltage of each station is changed to each separate one by the same operation as described above. The signals are sequentially memorized in the memory circuit, and the preset channel selection operation is completed.

The noise skip circuit 13 will now be described in more detail with reference to FIG. 2, which shows a specific circuit configuration diagram. and transistor Q
1. and a noise detecting section 15 consisting of a skip level adjusting variable resistor ■R0, etc., a synchronizing signal amplifying section 16 consisting of a transistor R2, etc., and a transistor Q3. Coil L1. L2°L3, capacitors C4, C5, C6, a diode D1% resistor R3, and a bandpass filter 17.

Here, it is assumed that the base bias voltage of the transistor Q1 of the noise detection section 15 is set to, for example, about 0.2 volts by the skip level adjusting variable resistor VR1.

When television radio waves are now being received in this state and a regular television vertical synchronizing signal is derived from the start/stop circuit 9, this is integrated by the integrating circuit section 14, and a signal as shown in Figure 3 is generated. can get.

Normally, the noise component superimposed on this synchronization signal is extremely small, so that the positive voltage of this signal does not reach the conduction level (0.6 volts) of transistor Q1, and transistor Q is in a cut-off state.

Therefore, at this time, no output signal, ie, a re-search start pulse, is derived from the noise detection section 15.

On the other hand, at this time, the synchronization signal is applied to the base of the transistor Q2 via the capacitor C1 (Fig. 3), and once amplified, a positive vertical synchronization signal as shown in Fig. 3 is output from the collector of the transistor Q2. The signal is derived and supplied to the signal discrimination circuit 12, and also to the tuning voltage generation circuit 10 as a search stop pass.

However, due to the variable resistor VR, the transistor Q
If the base bias voltage of 1 is set to about 0.5 volts, for example, when a particularly strong television radio wave is received and a regular vertical synchronization signal is derived, the level of the noise component superimposed on this synchronization signal will be Since it is extremely small, there is no need to turn on transistor Q1 to derive a re-search start pulse.

However, when weak radio waves are received, even if a regular vertical synchronization signal is derived from the start/stop circuit 9, the noise component superimposed on the synchronization signal is relatively thick, so the superposition of this noise component causes As shown in a, the conduction level (0.6 volts) of transistor Q may be exceeded, and the fourth voltage from the collector of transistor Q is
A pulse output as shown in FIG. 3 is obtained, which is returned to the start/stop circuit 9 as a re-search start pulse, and a re-search operation is performed.

Note that when a nozzle signal that is different from the synchronization signal is derived from the start/stop circuit 9, this noise signal has both positive and negative polarity components as shown in FIG. .

Since the conduction level becomes higher than the conduction level, the transistor Q is turned on each time, and a pulse output as shown in FIG. 5 is obtained from the collector of the transistor Q.

This is returned to the start/stop circuit 9 as a re-search start pulse, and a re-search operation is performed.

On the other hand, in the above-mentioned noise skip circuit 13, if the automatic channel selection device is operated in an area where television radio waves of two adjacent channels can be received simultaneously and this search operation is performed, the video carrier wave of the lower channel and the upper When receiving the audio carrier wave of the channel at the same time,
A regular vertical synchronizing signal is derived from the start/stop circuit 9, but at this time, since a beat frequency signal of 1°5 MHz is superimposed on the composite video signal obtained from the intermediate frequency circuit 3, the beat frequency signal is extracted through the bandpass filter 17, and at this time, the transistor Q3 is turned on.

Along with this, the transistor Q1 is also turned on, and a re-search start pulse is derived from the collector of the transistor Q1, and at this time, the re-search operation is performed again.

In this manner, the noise skip circuit 13 determines whether the signal obtained from the start/stop circuit 9 is a regular synchronization signal or a noise signal based on the positive voltage level of the signal, and performs synchronization.

The signal is supplied to the signal discrimination circuit 12 and the tuning voltage generation circuit, and the noise signal is supplied to the start/stop circuit 9 as a re-search start pulse.

Furthermore, even if it is determined to be a regular vertical synchronizing signal, when a 1.5 MHz beat frequency signal is detected, a re-search start pulse is derived and supplied to the start/stop circuit 9, and the re-search operation is continued. Ru.

Therefore, according to the automatic tuning device using the noise skip circuit as described above, not only a search stop command is not erroneously given to the tuning voltage generating circuit 10 due to the noise signal, but also a search stop command is not erroneously given to the tuning voltage generating circuit 10 due to the noise signal. Even when used in

In the above embodiment, when a 1.5 MHz beat frequency signal is detected through the band pass filter 17 of the noise skip circuit 13, the transistor Q1 is directly turned on based on the detection output to obtain a re-search start pulse. Here, an AND gate circuit is further inserted and the transistor Q1 is turned on based on the AND gate output of the output of the synchronous amplifier section 16 and the output of the band pass filter 17, and the search is started again especially when a beat frequency signal is detected during the synchronous signal period. If the pulses are derived, there is no possibility that the apparatus will malfunction due to the 1.5 MHz components contained in one composite video signal, and the apparatus will be more effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the automatic tuning device of the present invention, FIG. 2 is a circuit diagram of a noise skip circuit used in the embodiment, and FIGS. 3 to 5 are block diagrams of the noise skip circuit used in the embodiment. It is a signal waveform diagram of each part in a circuit. 1...Antenna, 2...Tuner, 3
......Intermediate frequency circuit, 4...Pa...AFT circuit, 5...Video circuit. 6... Synchronization separation circuit, 7... Deflection circuit, 8... Picture tube, 9... Start/stop circuit, 10... 9. . Tuning voltage generation circuit, 11...Memory circuit, 1
2... Signal discrimination circuit, 13... Noise skip circuit. 14...Integrator circuit section, 15...Noise detection section. 16... Tuning signal amplification section, 17... Band pass filter.

Claims (1)

[Claims] 1. Detecting a search start command for automatic channel selection operation and an incoming television signal to derive a search start/stop signal, and controlling the operation of a tuning voltage generation circuit based on the search start/stop signal. In an automatic channel selection device that
It has a noise detection means for detecting the noise level of an incoming television signal, and a beat frequency detection means for detecting a beat frequency signal of a video carrier wave and an audio carrier wave of an adjacent channel, and each of the above means detects noise exceeding a predetermined value. An automatic tuning device characterized by comprising a noise skip circuit that gives a search start/stop command to start a search again when a beat frequency signal is detected or when a beat frequency signal is detected. 2. Patent 3, characterized in that a 1.5 MHz bandpass filter is used as the beat frequency detection means. 3. Claim 3, characterized in that the beat frequency detection means detects a beat frequency signal during a synchronization signal period. The automatic channel selection device described in 1.