JP2565153B2 - System conversion device for television receiver - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a system conversion device of a television receiver capable of receiving television signals of different systems.

[Outline of Invention]

The present invention, in the system conversion device of the television receiver, stops the function of the M system priority circuit when the system switch is pressed, so that, for example, when a television signal when a disc of a different system is reproduced is displayed, It is designed so that it can be reproduced even in special cases.

[Conventional technology]

Various television systems are used in each country. Television receivers are generally set to comply with the television system of the country. Therefore, if the television system is different, the reproduction cannot be performed.
The color system also differs from country to country. The television receiver is set to match the color system of the country, and if the color system is different, the color image cannot be reproduced.

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

That is, there are standard television systems from A system to N system. The B and G methods are mainly used in Western Europe. Among Western European countries, I in England
The method is adopted, and the L method is adopted in France. The D, K method is mainly used in Eastern Europe. The M method is adopted in the United States, Canada, and Japan. The N method is adopted in Argentina.

The main differences between the systems are the field frequency, the number of scanning lines, and the audio carrier frequency with respect to the video carrier. The field frequency and the number of scanning lines are 60 for the M method.
Hz, 525 lines, B, G method, I method, L method, D, K method, M method 50H
It is z, 625. Audio carrier frequency for video carrier is 5.5MHz for B and G systems, 6MHz for I system, 6.5MHz for L system, D and K
The system is 6.5MHz, the M system is 4.5MHz, and the N system is 4.5MHz.

Color systems include PAL system, NTSC system, and SECAM system.
The PAL method is mainly used in Western European countries. The NTSC system is adopted in the United States, Canada and Japan. The SECAM 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 television receiver compatible with the multi-system has 50Hz and 625
We can handle books as well. Then, a trap circuit corresponding to an audio carrier frequency with respect to a video carrier in each television system is provided. These trap circuits are switched according to the television system of the received television signal. Also, PAL system, NTSC system,
It has a color decoder compatible with the SECAM color system.

A conventional multi-system compatible television receiver is provided with an automatic M mechanism that automatically sets the reception state of the M system when the input television signal is the M system.
Most of the countries that have adopted the M system television system have adopted the NTSC system as a color system. Therefore, at this time, many are set to the M system reception state and the NTSC system color reproduction state.

Whether the input television signal is the M system can be determined by determining whether the field frequency is 60 Hz and the number of scanning lines is 525. That is, of the currently widely used television systems, only the M system has a field frequency of 60 Hz and 525 scanning lines, and the other systems have a field frequency of 50 Hz and 625 scanning lines. Therefore, if the vertical synchronizing signal for a certain period of time is counted or the number of scanning lines of one screen is counted, it is possible to know whether it is the M system or not.

[Problems to be solved by the invention]

As described above, the conventional multi-system television receiver is provided with the automatic M mechanism. And
At this time, the M system reception state is set and the MTSC system color reproduction state is set. Such an automatic M mechanism is used when the input signal is an M type television signal.
It is very convenient because it is automatically set to the reception state of the system. However, on the other hand, inconvenience occurs in the following cases.

For example, when a video disc is played back using such a television receiver, some discs cannot be played back. That is, when the NTSC system disc is played back by the PAL system video disc player, the format of the output television signal of the video disc player is that the synchronous system has a field frequency of 60 Hz, the number of scanning lines is 525, and the audio frequency for the video carrier is It corresponds to B, G, and I methods, and the color method becomes the PAL method. At this time, since the field frequency of the television receiver is 60 Hz, the M system is set by the automatic M mechanism.

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

In order to solve the above-mentioned problems, it is possible to specially provide a switch for canceling the automatic M mechanism. However, when such a switch is provided, the switch has to be operated, for example, every time the disc is reproduced, and the operability is poor, and the provision of such a switch leads to an increase in cost.

Therefore, an object of the present invention is to reproduce a disc of a different color system and to perform a PA without a special switch.
It is an object of the present invention to provide a system selection device for a television receiver which is capable of being reproduced in the country of the L system and the M system.

[Means for solving problems]

The present invention has an M system priority circuit and a system selection switch. When the system selection switch is pressed, the function of the M system priority circuit is stopped, and a change in the signal state is detected to make the function of the M system priority circuit. It is a system conversion device for a television receiver that is adapted to be restored.

[Action]

When the system switch 1 is pressed, the function of the M system priority circuit is stopped, and by pressing the system switch 1, it is possible to set a reception state of an arbitrary system. When the channel switch 2 is pressed, the M system priority circuit is restored and the automatic M mechanism operates.

〔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, the reception states of the M, I, B, G, D, and K television systems can be set. Also, NTSC system, P
AL system and SECAM system reception status can be set. In FIG. 1, reference numeral 1 is a system switch for setting the method. The system switch 1 is a toggle switch, and the television system is switched by pressing the system switch 1. Reference numeral 2 is a channel switch for setting a reception channel.

When the reception mode of the M system is set, the trap circuit of the IF signal processing circuit 7 is switched to the one of 4.5 MHz for the image carrier by the command from the controller 3, and the audio circuit 8 changes the beat component of the frequency 4.5 MHz from the beat component. The audio signal is demodulated. When set to the reception state of the I system, the trap circuit of the IF signal processing circuit 7 is switched to the one of 6 MHz for the video carrier, and the audio circuit 8 demodulates the audio signal from the beat component of 6 MHz. When the reception state of B, G system is set, the trap circuit of the IF signal processing circuit 7 is switched to 5.5 MHz for the image carrier, and the audio circuit 8 is 5.5 M
The audio signal is demodulated from the beat component in Hz. When the D, K reception mode is set, the trap circuit of the IF signal processing circuit 7 is switched to 6.5 MHz for the video carrier, and the audio circuit 8 demodulates the audio signal from the 6.5 MHz beat component. It

Most of the countries that have adopted the M system as the television system have adopted the NTSC system as the color system, and most of the countries that have adopted the I system, B, G system as the television system have PAL as the color system. Most of the countries that have adopted the system and have adopted the D, K system as the television system have adopted the SECAM system as the color system.

Therefore, in this embodiment, when the reception mode of the M system is set, the NTSC decoder 9 enters the operating state, the output of the NTSC decoder 9 is output through the selector 12, and the reception of the I system and the B and G systems is performed. When it is set to the state, the PAL decoder 10 becomes the operation state, the output of the PAL decoder 10 is output through the selector 12, and when it is set to the D, K system reception state, S
The ECAM decoder 11 is in the operating state, and the output of the SECAM decoder 11 is output via the selector 12.

A system switch for switching the color system may be separately provided so that the color system can be set independently of the setting of the television system.

In FIG. 1, the television signal received by the television antenna 5 is supplied to the receiving circuit 6. The receiving circuit 6 selects the television signal of the channel designated by the channel switch 2. The output of the receiving circuit 6 is IF
It is 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 supplied to the NTSC decoder 9, the PAL decoder 10, the SECAM decoder 11 and the audio circuit 8. Further, the synchronizing signal in the video signal output from the IF signal processing circuit 7 is extracted and the deflection circuit 13
Is supplied to.

A sawtooth wave for horizontal deflection and vertical deflection is formed based on the synchronizing signal separated by the deflection circuit 13. This sawtooth wave is passed through the horizontal and vertical deflection coils of the cathode ray tube 15. Even if the deflection circuit 13 has a field frequency of 60 Hz and 525 scanning lines,
It is designed to be compatible with 50 Hz and 625 scanning lines.

Also, the separated sync signal is supplied to the M-system detection circuit 14, and the M-system detection circuit 14 detects whether the received signal has a field frequency of 60 Hz or the number of scanning lines is 525. Since the television signal with the field frequency of 60 Hz and the number of scanning lines of 525 is only the television signal of the M system, it can be known from this that the received signal is of the M system or other. However, when the reproduction signal of the video disc is input, the method cannot be determined from the field frequency and the number of scanning lines. The detection output of the M type detection circuit 14 is supplied to the controller 3.
When the M system detection circuit 14 detects that the field frequency is 60 Hz or the number of scanning lines is 525, the M system reception state is preferentially set.

Whether the field frequency is 60 Hz or not can be easily determined by counting vertical sync signals for a certain period of time. Further, as shown in FIG. 2, whether the number of scanning lines is 525 is determined by opening the AND gate 21 for a time corresponding to one frame by the pulse V _{P for} a time corresponding to one frame formed by the vertical synchronizing signal. , The horizontal synchronizing signal H _SYNC is supplied to the counter 22 via the AND gate 21 and the horizontal synchronizing signal of one frame is counted.

In the reception state of the M system, the output of the NTSC decoder 9 is output through the selector 12, and the output of the selector 12 is the adder circuit.
It is supplied to the cathode ray tube 15 via 16. In response to a command from the controller 3, the display circuit 17 generates a display character indicating the M system or the NTSC system, and the addition circuit 16 superimposes the display character. The audio circuit 8 demodulates the audio signal from the beat component of 4.5 MHz and supplies the audio output signal to the speaker 18.

In the reception state of the I system, the output of the PAL decoder 10 is output via the selector 12, and the output of the selector 12 is the addition circuit.
It is supplied to the cathode ray tube 15 via 16. In response to a command from the controller 3, the display circuit 17 generates a display character indicating the I system or the PAL system, and the addition circuit 16 superimposes the display character. The audio circuit 8 demodulates the audio signal from the beat component of 6 MHz and supplies the audio output signal to the speaker 18.

In the B / G reception state, the output of the PAL decoder 10 is output through the selector 12, and the output of the selector 12 is an adder circuit.
It is supplied to the cathode ray tube 15 via 16. The display circuit 17 generates a display character indicating the B, G method, or the PAL method in response to a command from the controller 3, and the addition circuit 16 superimposes the display character. The audio circuit 8 demodulates the audio signal from the 5.5 MHz beat component and supplies the audio output signal to the speaker 18.

In the D, K system reception state, the output of the SECAM decoder 11 is output via the selector 12, and the output of the selector 12 is supplied to the Braun tube 15 via the adder circuit 16. From the display circuit 17, by the command from the controller 3, D, K system, SECAM
A display character indicating that the system is used is generated, and the addition circuit 16
The displayed character is superimposed with. The audio circuit 8 demodulates the audio signal from the beat component of 6 MHz and supplies the audio output signal to the speaker 18.

As described above, in this embodiment, the M type detection circuit is used.
Based on the detection output of 14, the M method is preferentially set. By the way, when the reproduction signal of the video disc is supplied to the receiving circuit 6 and the reproduction of the video disc is performed, it is judged whether or not it is the M system depending on whether the field frequency is 60 Hz or the number of scanning lines is 525, and the M system is determined. If it is judged, set to M system, NTSC system reception state, and M
If it is judged that it is not the system, if you set it so that it cannot be set to M system or NTSC system, for example, NTSC system disk is PAL.
It is not supported when playing back on a video disc of the same system. Therefore, as shown in the flow chart of FIG. 3, even if the M method is preferentially set, it is possible to shift to the reception state of another method by pressing the system switch 1. Then, when the channel switch 2 is pressed, the M method is preferentially set again.

That is, as shown in FIG. 3, it is judged from the output of the M method detection circuit 14 whether or not the field frequency is 60 Hz (step). Note that it may be determined whether the number of scanning lines is 525. When the field frequency is 60 Hz, the M method is set (step). It is judged whether or not the system switch 1 is pressed (step), and if the system switch 1 is not pressed, the setting state of the M system is held. In this way, the automatic M mechanism operates.

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

When the system switch 1 is pressed in the step, the B or G method is set (step), and it is determined whether or not the system switch is pressed (step). If system switch 1 is not pressed,
It is determined whether or not the channel switch 2 has been pressed (step). If the channel switch 2 has not been pressed, the process returns to step and the B, G system setting state is set.

When the system switch 1 is pressed in the step, the D, K method is set (step), and it is determined whether the system switch 1 is pressed (step). If the system switch 1 is not pressed, it is determined whether the channel switch 2 is pressed (step). If the channel switch 2 is not pressed, the process returns to the step and the D, K system setting state is set.

When the system switch 1 is pressed in step, the process returns to step and the M system setting state is set.

When it is determined that the channel switch 2 is pressed in step, step, step, the process returns to step.

As can be seen from this flowchart, when the received television signal is 60 Hz, the M system is automatically set.

System switch 1 even if automatically set to M mode
If is pressed, the automatic M mechanism is released, and by pressing the system switch 1, the reception state can be switched to I system → B, G system → D, K system → M system.

When the channel switch 2 is pressed, the automatic M mechanism operates again, and when the received television signal is 60 Hz, the M system is automatically set.

〔The invention's effect〕

According to the present invention, when the system switch 1 is pressed, the automatic M mechanism is stopped and the reception state can be set to an arbitrary method. Therefore, for example, as when playing back an NTSC disc with a PAL video disc player, the synchronization system is the M system, and the audio frequencies are the B, G systems, and I system.
It is also possible to play back PAL system television signals in color and system. And channel switch 2
When is pressed, the automatic M mechanism operates again. As described above, according to the present invention, since the automatic M mechanism can be released without providing a special switch for releasing the automatic M mechanism, the cost can be reduced and the operability is good.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG.
FIG. 3 is a block diagram used to explain the method detection, and FIG. 3 is a flowchart used to explain one embodiment of the present invention. Description of main symbols in the drawings 1: System switch, 2: Channel switch, 3: Controller, 14: M type detection circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kyoji Baba 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Within Sony Corporation (56) Reference JP-A-57-185776 (JP, A) JP-A-SHO 59-92681 (JP, A) Actual development Sho 59-76176 (JP, U)

Claims (1)

(57) [Claims] 1. A field frequency of 60 Hz or a horizontal scanning line number of approximately 525 makes it possible to judge that the input signal is the M system and select the demodulation signal of the NTSC decoder. It has a system priority circuit and a system selection switch for selecting and outputting demodulated signals of different color system decoders. When the system selection switch is pressed, the function of the M system priority circuit is stopped and the NTSC A system converter for a television receiver, which selects a demodulated signal from a decoder of a color system other than the above and restores the function of the M system priority circuit in conjunction with the switching of the receiving channel.