JPS6345982A - System converter for television receiver - Google Patents

Abstract

PURPOSE:To set a converter the reception state of an optical system by stopping the function of a m system priority circuit when a system selection switch is depressed to detect the change in the signal state thereby recovering the function of the M system priority circuit. CONSTITUTION:A trap circuit of an IF signal processing circuit 7 is switched based on a television set by the control of a controller 3. The output of the IF signal processing circuit 7 is fed to a NTSC decoder 9, a PAL decoder 10, a SECAM decoder 121 and also to a sound circuit 8. A separated synchroniz ing signal is fed to a M system detection circuit 14 and the detection output of the M system detection circuit 14 is fed to the controller 3. When it is detected that the field frequency is 60Hz or the number of scanning lines is 525, then the M system reception state is set with priority.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a format conversion device for a television receiver that can receive television signals of different formats.

[Summary of the invention]

This invention is a system conversion device for a television receiver, by stopping the function of the M system priority circuit when the system selection button is pressed. This makes it possible to perform playback even in such cases.

[Conventional technology]

Various television systems are used in each country. Television receivers are generally set to match the television system of the country. Therefore, if the television system is different, playback cannot be performed. The Kara one style also differs depending on the country. Television receivers are set to match the country's color system, and cannot reproduce color images if the color system is different.

A multi-system compatible television receiver can be used even in countries with different television systems and color unidirectional systems. If such a television receiver is used, reproduction can be performed even in countries where the television system and color system are different.

In other words, standard television systems range from system A to system N. The B and G systems are mainly used in Western Europe. Among Western European countries, the UK has 1
In France, the L method has been adopted. Method D is mainly adopted in Eastern Europe. The M method has been adopted in the United States, Canada, and Japan. The N method is used in Argentina.

The main differences between the systems are the field frequency and number of scan lines, and the audio carrier frequency relative to the video carrier. The field frequency and number of scanning lines are 60 for the M method.
H! , 525 pieces, B, G method, 1 method, L method,
D, K system 1M system is 50Hz, 625 lines. The audio carrier frequency for the video carrier wave is 5 for B and G systems.
．． 5MHz, 1 method is 6Mtlz, L method is 6.5
M1 (6.5 MHz for Z, D, K methods, 4.5 MB for M methods, 4.5 MB for N methods) Iz.

Color one-sided systems include PAL system, NTSC system, and SECAM system.
There is a method. The PAL system is mainly adopted in Western European countries. The NTSC system is used in the United States, Canada, and Japan.

The SF':CAM method is adopted in France and Eastern European countries.

Even if the field frequency and the number of scanning lines are 60Hz and 525 lines, a multi-system compatible television receiver will
It can also handle cases of 0Hz and 625 lines. Trap circuits corresponding to audio carrier frequencies for video carrier waves in each television system are provided.

These trap circuits are switched depending on the television system of the received television signal. Also, P.A.
It has a color decoder that is compatible with L, NTSC, and SECAM color systems.

Conventional multi-system television receivers are provided with an automatic M mechanism that automatically sets the M system reception state when an input television signal is M system. M
Most of the countries that have adopted the television system have adopted the NTSC system as a color one-way system. Therefore, at this time, many devices are set to the M system reception state and also set to the N''I'SC color reproduction state.

Whether the input television signal is of the M format can be determined by determining whether the field frequency is 60 Hz and the number of scanning lines is 525. That is, among the television systems currently widely used, only the M system has a field frequency of 6011z.

The number of scanning lines is 525, and the field frequency of other systems is 50.
Hz, and the number of scanning lines is 625. Therefore, by counting vertical synchronization signals for a certain period of time or by counting the number of scanning lines in one screen, it can be determined whether the M system is used.

[Problem that the invention seeks to solve]

As described above, conventional multi-system compatible television receivers are provided with an automatic M mechanism. At this time, the M system reception state is set, and the MTSC system color reproduction state is set. Such an automatic M mechanism, when the input signal is an M format television signal,
It is very convenient because it is automatically set to receive the M method.

However, on the other hand, inconveniences occur in the following cases.

For example, when playing back a video disc using such a television receiver, depending on the disc, playback may not be possible. In other words, when an NTSC disc is played back by a PAL video disc player, the format of the output television signal from the video disc player is that the synchronization system has a field frequency of 60 Hz, the number of scanning lines is 525, and the audio frequency relative to the video carrier wave is B,G
method.

1 system, and the color one system becomes the PAL system.

At this time, the field frequency of the television receiver is 6.
Since it is 0 Hz, the automatic M mechanism will set it to the M method.

For example, in Brazil, the M system is adopted as the television system, and the PAL system is adopted as the color one-way system. In this case, since the television system is the M system, the automatic M mechanism sets the M system reception state, and the N
The color reproduction state of the TSC method is set. On the other hand, since the color input television signal is PAL, color reproduction cannot be performed.

In order to solve the above-mentioned problems, it is conceivable to provide a special switch for canceling automatic Ml1m. However, when such a switch is provided, the switch must be operated each time a disc is reproduced, resulting in poor operability and the provision of such a switch leads to an increase in cost.

Therefore, it is an object of the present invention to enable playback of different discs in a single-color system and PA without the need for a special switch.
An object of the present invention is to provide a system selection device for a television receiver that allows reproduction of L system in countries using M system.

[Means for solving problems]

This invention has an M system priority circuit and a system selection switch, and when the system selection switch is pressed, the function of the M system priority circuit is stopped, a change in the signal state is detected, and the M system selection switch is activated.
This is a system conversion device for a television receiver that restores the function of the system priority circuit.

[Effect]

When the system switch 1 is pressed, the function of the M system priority circuit is stopped, and by pressing the system switch 1, the receiving state can be set to any system. When the channel switch 2 is pressed, the M system priority circuit is restarted and the automatic M mechanism is activated.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

In this embodiment, M method, 1 method, B, and G methods are used.

D. You can set the reception status of the television system. Additionally, the reception status of NTSC, PAL, and SECAM systems can be set. In FIG. 1, 1 is a system switch for setting the method. The system switch 1 is a toggle switch, and by pressing the system switch 1, the television system can be switched. 2
is a channel switch for setting the reception channel.

When the receiving state of the M method is set, the trap circuit of the IF signal processing circuit 7 is switched to a 4.5 MHz one for the video carrier wave by a command from the controller 3,
The audio circuit 8 demodulates the audio signal from the beat component with a frequency of 4.5 M)+2. When the reception state of 1 system is set, the trap circuit of the IF signal processing circuit 7 is switched to the 6M) IzO one for the video carrier wave, and the trap circuit of the IF signal processing circuit 7 is switched to the 6M) IzO one for the video carrier wave
Then, the audio signal is demodulated from the 6 MHz beat component.

When set to the B or G reception state, the IF signal processing time W! The trap circuit of I7 is 5.5 to the video carrier.
5.5 in audio circuit 8.
An audio signal is demodulated from the beat component at MHz. D.
When the receiving state of the method is set, the IF signal processing circuit 7
The trap circuit is switched to a 6.5 MHz trap circuit for the video carrier wave, and the audio circuit 8 demodulates the audio signal from the 6.5 MHz beat component.

Most of the countries that have adopted the M system as their television system have adopted the NTSC system as their color system, System 1, and B as their television system.

Most countries that use the G system use the PAL system as the color system, and the television system as the television system.
Most of the countries that have adopted the K system have adopted the SECAM system as a one-sided system.

Therefore, in this embodiment, when the M system reception state is set, the NTSC decoder 9 enters the operating state, and the NTSC decoder 9 enters the operating state.
The output of the C decoder 9 is outputted via the selector 12,
When set to receive mode 1, B, and G, the PA
L, decoder lO becomes operational, and PAL decoder 1
0 is output via the selector 12, and D, K
When set to receive mode, SECAM decoder 1
1 is in the operating state, and the output of the SECAM decoder 11 is outputted via the selector 12.

Note that a system switch for switching between the color and one-way systems may be provided separately so that the color and one-way systems can be set independently of the setting of the television system.

In FIG. 1, a television signal received by a television antenna 5 is supplied to a receiving circuit 6. As shown in FIG. The receiving circuit 6 selects the television signal of the channel specified by the channel switch 2. The output of the receiving circuit 6 is IF
4Jj can be supplied to the signal processing circuit 7. As described above, the trap circuit of the IF signal processing circuit 7 is switched based on the set television system under the control of the controller 3. The output of the IF signal processing circuit 7 is sent to the NTSC decoder 9. PAL decoder 10.3 ECAM decoder 11
and is also supplied to the audio circuit 8. Also,
A synchronizing signal from the video signal output from the IF signal processing circuit 7 is extracted and supplied to the deflection circuit 13.

Based on the synchronization signal separated by the deflection circuit 13, sawtooth waves for horizontal and vertical deflections are formed. This sawtooth wave is applied to the horizontal deflection coil and vertical deflection coil of the cathode ray tube 15. Note that the deflection circuit 13 is designed to be compatible with both cases where the field frequency is 60 Hz and the number of scanning lines is 525, and the case where the field frequency is 50112 and the number of scanning lines is 625.

Further, the separated synchronization signal is supplied to the M method detection circuit 14, and the M method detection circuit 14 detects whether the field frequency of the received signal is 60)1z or the number of scanning lines is 525. It will be done. Field frequency is 60H
z, the only television signal with 525 scanning lines is an M system television signal, so it can be determined whether the received signal is an M system or something else. However, if a video disc playback signal is input,
The method cannot be determined from the field frequency or the number of scanning lines. The detection output of the M method detection circuit 14 is supplied to the controller 3. When the M method detection circuit 14 detects that the field frequency is 60 Hz or the number of scanning lines is 525, the M method reception state is preferentially set.

Whether the field frequency is 60 Hz or not can be easily determined by counting vertical synchronization signals for a certain period of time.

Also, whether or not the number of scanning lines is 525 can be determined by controlling the AND gate 21 by a pulse (1) of a time corresponding to one frame formed by the vertical synchronization signal, as shown in FIG.
Time interval corresponding to frame, horizontal synchronization signal H5VNC
is supplied to the counter 22 via the AND game) 21, and 1
This can be determined by counting the horizontal synchronization signals of the frames.

In the M system reception state, the output of the NTSC decoder 9 is outputted via the selector 12, and the output of the selector 12 is supplied via the adder circuit 16 to the cathode ray tube 15. The display circuit 17 generates display characters indicating the M system and the NTSC system according to a command from the controller 3, and the display characters are superimposed in the addition circuit 16. An audio signal is demodulated from the 4.degree. 5 MHz beat component in the audio circuit 8, and an audio output signal is supplied to the speaker 18.

In the 1-system reception state, the output of the FAI and decoder 10 is output via the selector 12, and the output of the selector 12 is supplied via the adder circuit 16 to the cathode ray tube 15. 1 from the display circuit 17 according to a command from the controller 3.
A display character indicating that the system is a PAL system is generated, and the display character is superimposed in an adding circuit 16. An audio signal is demodulated from the 6 MHz beat component in the audio circuit 8, and an audio output signal is supplied to the speaker 18.

In the B, G system reception state, the output of the PAL decoder 10 is outputted via the selector 12, and the output of the selector 12 is supplied via the adder circuit 16 to the cathode ray tube 15.

From the display circuit 17, based on the command from the controller 3,
Display characters indicating the B, G system, and PAL system are generated, and the display characters are superimposed in the adding circuit 16. The audio circuit 8 demodulates the audio signal from the 5.5 MHz filtered component and supplies the audio output signal to the speaker 18.

In the receiving state of the D, method, the output of the SECAM decoder 11 is outputted via the selector 12, and the output of the selector 12 is supplied via the adder circuit 16 to the cathode ray tube 15. In response to a command from the controller 3, the display circuit 17 generates display characters indicating that the system is D, the SECAM system, and the adder circuit 16 superimposes the display characters.

An audio signal is demodulated from the 6 MHz beat component in the audio circuit 8, and an audio output signal is supplied to the speaker 18.

As mentioned above, in this embodiment, the M method detection circuit 1
Based on the detection output No. 4, the M method is set preferentially. By the way, when the reproduction signal of the video disc is supplied to the receiving circuit 6 and the video disc is reproduced, it is not necessary to determine whether the field frequency is 60 Hz or the number of scanning lines is 52.
It is determined whether it is the M method or not depending on whether there are 5 or not. If it is determined to be the M method, the reception state is set to the M method and NTSC method. If it is determined that it is not the M method, it is set to the M method and NTSC method.
If the C format cannot be set, it will not be possible to play back an NTSC format disc with a PAL video disc, for example. Therefore, as shown in the flowchart of FIG. 3, even if the M method is set as a priority, by pressing the system switch 1, it is possible to shift to the receiving state of another method. Then, when the channel switch 2 is pressed, the M method is set preferentially again.

That is, as shown in FIG. 3, it is determined whether the field frequency is 60 Hz based on the output of the M method detection circuit 14 (step 2). Note that it may be determined whether the number of scanning lines is 525 or not. If the field frequency is 60Hz, it can be set to M method (step ■)
. It is determined whether system switch 1 has been pressed (
In step (2), if the system switch 1 is not pressed, the setting state of the M method is maintained. In this way,
Automatic M mechanism operates.

If the field frequency is not 60 Hz in step (2), or if system switch 1 is pressed in step (2), the system is set to 1 (step (2)). 1 method is set, it is determined whether the system switch is pressed (step ■), and if the system switch is not pressed, it is determined whether channel switch 2 is pressed (step ■), and the channel If switch 2 is not pressed, the process returns to step (2) and the 1 method setting state is reached.

In step ■, if the system switch l is pressed, the B and G methods are set (step ■), and it is determined whether the system switch is pressed (step ■)
. If system switch 1 is not pressed, it is determined whether channel switch 2 is pressed (step ■), and if channel switch 2 is not pressed, the process returns to step ■, and the B and G method setting state is returned. Become.

In step (2), if system switch 1 is pressed, method D is set (step [phase]), and it is determined whether system switch 1 is pressed (step (2)). If system switch l is not pressed, it is determined whether channel switch 2 is pressed (step @), and if channel switch 2 is not pressed, the process returns to step [phase] and enters the D and K method setting state. Become.

If the system switch 1 is pressed in step q), the process returns to step (2) and the M method setting state is entered.

If it is determined in step (2), step (2), and step @ that the channel switch 2 has been pressed, the process returns to step (2).

As can be understood from this flowchart, when the received television signal is 6011z, the M
Set to method.

Even if the M method is automatically set, if the system switch 1 is pressed, the automatic M mechanism is canceled, and by pressing the system switch 1, the system 1-I3. G method-D
, the reception state can be switched to method-M method.

When the channel switch 2 is pressed, the automatic M mechanism is activated again, and if the received television signal is 60112, the M system is automatically set.

〔Effect of the invention〕

According to this invention, when the system switch 1 is pressed,
The automatic M mechanism is stopped and the reception state can be set to any method. For this reason, for example, when playing an NTSC disc on a PAL video disc player, the synchronization system is the M system, and the audio frequency is the B and G systems.

It is also possible to reproduce television signals of PAL format. Then, when the channel switch 2 is pressed, the automatic M mechanism operates again. As described above, according to the present invention, the automatic M mechanism can be canceled without providing a special switch for canceling the automatic M mechanism, resulting in cost reduction and good operability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of this invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
FIG. 3 is a block diagram used to explain the method of detection, and FIG. 3 is a flowchart used to explain one embodiment of the present invention. Explanation of main symbols in the drawings 1. System switch, 2. Channel switch,
3: Controller, IIM method detection circuit. Agent Patent Attorney Masato Sugiura Figure 3

Claims (1)

[Claims] It has an M system priority circuit and a system selection switch, and when the system selection switch is pressed, the function of the M system priority circuit is stopped, a change in the signal state is detected, and the M system selection switch is activated.
A system conversion device for a television receiver that restores the function of the system priority circuit.