JPS5924232Y2 - Dual color television receiver - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a dual-system color television receiver, which is one of two predetermined systems among PAL system color television broadcasting, SECAM system color television broadcasting, and NTSC system color television broadcasting. To provide a dual-system color television receiver that can selectively receive color television broadcasting of one of the systems and automatically select and receive only the color television broadcasting of the desired system accurately and without malfunction. The purpose is to

FIG. 1 shows a block system diagram of an example of a conventional PAL-5ECAM dual system color television receiver.

In the figure, the carrier color signal in the PAL color television signal or the SECAM color color television signal color signal input from the input terminal 1 is sent to the PAL color signal processing circuit 2 and the SECAM color signal processing circuit 3, respectively. Supplied.

The PAL color signal processing circuit 2 demodulates only the PAL carrier color signal in the input signal and outputs it.

On the other hand, the SECAM color signal processing circuit 3 demodulates and outputs only the SECAM type carrier color signal in the input signal.

The output color signal of the PAL color signal processing circuit 2 and the SECA
The output color signals of the M color signal processing circuit 3 are supplied to switching circuits 6, respectively.

A killer circuit 4 is included in the PAL color signal processing circuit 2, and when receiving black and white television broadcasting, the output DC voltage of this killer circuit 4 is applied to the PAL color signal processing circuit 2.
stop working.

Similarly, a killer circuit 5 is included in the SECAM color signal processing circuit 3, and when receiving black and white television broadcasting, the output DC voltage of this killer circuit 5 is used to control the SECAM color signal processing circuit 3.
The operation of the color signal processing circuit 3 is stopped.

Here, in a PAL-8ECAM dual system color television receiver, the desired received television signal is
Switching circuit 6 depending on L method or SECAM method
In order to simplify the operability of television receivers, a function to automatically perform the switching is required.

Therefore, generally, the above-mentioned dual system color television receiver uses the output DC voltage of one of the killer circuits 4 and 5 to determine the color signal system, and the output DC voltage of the killer circuit is determined by using the output DC voltage of one of the killer circuits 4 and 5. The voltage is applied to the switching terminal 7 of the switching circuit 6 to switch the switching circuit 6, thereby automatically switching the color signal.

Here, the method using the output DC voltage of the killer circuit 4 is called the PAL detection type, and the method using the output DC voltage of the killer circuit 5 is called the SECAM detection type.

The conventional receiver shown in Fig. 1 has a SECAM color signal processing circuit 3.
The output DC voltage of the killer circuit 5 in the switching circuit 6
SEC configured to be applied to switching terminal 7 of
It is considered to be an AM detection type.

In the case of this SECAM detection type, the output DC voltage of the killer circuit 5 is high when receiving SECAM color television broadcasting, and is low when receiving PAL color television broadcasting or black and white television broadcasting.
At the same time as operating or stopping the AM color signal processing circuit 3, the switching circuit 6 is caused to output the output color signal of the SECAM color signal processing circuit 3 from the switching circuit 6 when receiving SECAM color television broadcasting, and on the other hand,
When receiving an AL color television signal or a monochrome television broadcast, switching is performed so that only the output signal of the PAL color signal processing circuit 2 passes through the switching circuit 6.

Note that when receiving a black and white television broadcast, the killer circuit 4 stops the color signal processing operation of the PAL color signal processing circuit 2, so no output signal is taken out from the PAL color signal processing circuit 2, and therefore no output signal is taken out from the switching circuit 6. is not taken out.

The color signal taken out from the above switching circuit 6 is
It is supplied to the cathode ray tube 8 together with a luminance signal from a luminance signal processing system in the receiver (not shown), and thereby the SECA
Correct color images are reproduced by automatically switching the color signal output corresponding to the above-mentioned broadcasting system of the desired channel in areas where both M system and PAL system television broadcasting can be received.

However, in the case of the above-mentioned SECAM detection type dual system color television receiver, the color subcarrier frequency of the PAL system color television signal and the color subcarrier frequency of the SECAM system color television signal are extremely close to each other. , deterioration of signal-to-noise ratio due to long-distance reception,
When the reception condition of PAL color television broadcasting deteriorates due to ghost waves in urban areas or interference from adjacent channel broadcasting stations, the killer circuit 5 becomes unable to determine whether the broadcast being received is PAL format or SECAM format. Even though PAL color television broadcasting is being received, the output DC voltage of the killer circuit 5 in the SECAM color signal processing circuit 3 sometimes becomes high, causing the switching circuit 6 to be switched to the SECAM side.

In addition, in the case of a PAL detection type dual system color television receiver, if the reception condition of SECAM system color television broadcasting deteriorates due to the same reason as above, the killer circuit 4 which outputs the switching DC voltage of the switching circuit 6 The output DC voltage became high, and the switching circuit 6 was sometimes switched to the PAL side even though SECAM color television broadcasting was being received.

In this way, the conventional PAL SECAM dual system color television receiver shown in Fig. 1 automatically switches depending on the format of the color television signal of the desired channel to be received. Circuit 6 malfunctions,
It had a major drawback in that it was unable to receive the intended color television broadcast.

FIG. 2 shows a block system diagram of another example of a conventional PAL-5ECAM dual system color television receiver.

In the figure, the same parts as in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted.

In FIG. 2, reference numeral 9 denotes a manual changeover switch having three contacts P, A, and S, the movable contact piece of which is connected to the changeover terminal 7 of the switching circuit 6.

The changeover switch 9 is normally connected to the contact A position, thereby providing an automatic switching operation similar to that shown in FIG.

However, if the reception condition of color television broadcasting is poor, the changeover switch 9 is connected to contact P when receiving PAL color television broadcasting, and a low DC voltage is applied to the switching terminal 7, thereby switching the switching circuit. 6 is forcibly switched to pass the output signal of the PAL color signal processing circuit 2.

Also, when receiving SECAM color television broadcasting,
If the reception condition is poor, the changeover switch 9 is switched to the contact S side so that a voltage higher than the DC power supply 10 is not applied to the changeover terminal 7, thereby forcing the switching circuit 6 to process the SECAM color signal. It is switched to pass the output signal of circuit 3.

As a result, like the television receiver shown in the first diagram,
It is possible to eliminate the drawback that the switching circuit 6 malfunctions when the reception condition deteriorates, making it impossible to receive the television broadcast of a desired channel.

However, in the conventional dual system color television receiver shown in Figure 2, each time a user in an area with poor reception changes the receiving channel, it is checked whether the channel is being broadcast in the SECAM system or the PAL system. If the color television broadcasting method of the channel to be received is different from the previously received channel, it is necessary to switch the selector switch 9 to the position of contact P or S, which makes the operation of the color television receiver extremely complicated. It had drawbacks.

The present invention eliminates the above-mentioned drawbacks, and the following third points are explained below.
One embodiment will be described with reference to the drawings.

FIG. 3 shows a block system diagram of an embodiment of the dual color television receiver according to the present invention.

In the figure, the same parts as in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted.

In this embodiment, a changeover switch 11 having contacts a and b is provided at the input part of a changeover terminal 7 of a switching circuit 6, and the switch 11 is connected to the point where the killer circuits 4 and 5 can arbitrarily select the switching DC voltage generated. Has characteristics.

That is, when the changeover switch 11 is connected to the contact a side, the output terminal of the killer circuit 4 is connected to the changeover terminal 7 via the changeover switch 11, so it becomes a PAL detection type, and the receiver,
When the changeover switch 11 is connected to the contact side, the output end of the killer circuit 5 is connected to the changeover terminal 7 via the changeover switch 11, resulting in a SECAM detection type.

This configuration was based on the inventor's attention as follows.

Firstly, in general, there are many regions in the Middle East where both PAL and SECAM color television broadcasting can be received, and relatively small countries are adjacent to each other.
The color television broadcasting system of one's own country and the color television broadcasting system of a neighboring country are different, and the color television broadcasting of one's own country has good reception because it is received over a short distance, but the color television broadcasting from a neighboring country is received over a long distance. Reception is often poor.

That is, in the above-mentioned areas, reception conditions for either the PAL system or the SECAM system are poor, but the reception condition for the other is often good.

Second, as mentioned above, in the SECAM detection type, the received color television broadcast is in the PAL system and malfunctions occur if the reception condition is poor; on the other hand, in the PAL detection type, the received color television broadcast is in the SECAM system and malfunctions. It malfunctions if the reception condition is poor.

In addition, if the reception condition of the received SECAM color television broadcast is poor in the SECAM detection type, or if the
If the reception condition of the received PAL color television broadcast is poor in the AL detection type, the killer circuit will simply stop the operation of the color signal processing circuit, which will cause the malfunction to be determined as a color television broadcast of another system. does not occur.

In view of the above two points, the present invention provides a changeover switch 11 as shown in FIG.
1 switching is performed.

That is, in areas where the reception condition of SECAM color television broadcasting is good but the reception condition of PAL color television broadcasting is poor, the changeover switch 11 is connected to the contact a side to provide a PAL detection type.

On the other hand, contrary to the above, in areas where the reception condition of PAL color television broadcasting is good but the reception condition of SECAM color television broadcasting is poor, it is possible to connect the selector switch 11 to the contact side and switch to the SECAM detection type. do.

With such a switching connection of the changeover switch 11, as explained in conjunction with FIG. 1, color signal processing systems of PAL and SECAM systems can be automatically switched to the desired channel without causing any malfunction. only those signals are selectively received.

According to the dual system color television receiver of this embodiment, the malfunction of automatic switching, which is a drawback of the conventional dual system color television receiver shown in FIG. 1, does not occur.

Moreover, since conventional automatic switching dual system color television receivers have been configured with either a SECAM detection type or a PAL detection type (the one shown in Figure 1 is a SECAM detection type), for example, in the case of a SECAM detection type, In areas with poor reception of PAL color television broadcasting, use is restricted due to the above malfunction.
According to this embodiment, by switching the changeover switch 11, S
It can be used in most areas where both ECAM and PAL color television broadcasts can be received.

Further, the above-mentioned switching operation of the changeover switch 11 may be performed only once depending on the receiving area of the color television receiver, and thereafter, if the receiving channel is PAL color television broadcasting, the PAL color signal will be used. Only the color signal from processing circuit 2 is output, and the receiving channel is SEC.
SECAM for AM color television broadcasting
so that only the color signal from the color signal processing circuit 3 is output.
The switching circuit 6 will be automatically switched.

Therefore, unlike the conventional dual-system color television receiver shown in FIG. 2, the complicated operation of switching the manual selector switch 9 each time depending on the color or color reception channel is eliminated according to this embodiment. It disappears completely.

In the above embodiment, the switching DC voltage of the switching circuit 6 is supplied to the killer circuits 4 and 5 for operating and stopping the PAL color signal processing circuit 2 and the SECAM color signal processing circuit 3. Although the output DC voltage is shared, the output DC voltage of the killer circuits 4 and 5 is not limited to this, and the related DC voltage that changes in the same way as the output DC voltage of the killer circuits 4 and 5 is shared with other parts of the killer circuits 4 and 5. Alternatively, it may be taken out from another circuit section and used.

In addition, in the above embodiment, for convenience of explanation, PAL system and S
Although we have described a television receiver that can selectively receive ECAM color television broadcasts, we will also cover color television receivers that can selectively receive NTSC and PAL color television broadcasts, or NTSC and SECAM color television broadcasts. Of course, it can also be applied in the same way.

As described above, the dual color television receiver according to the present invention includes a killer circuit in the first color signal processing circuit that processes the carrier color signal in the first color television signal. the output DC voltage or the related DC voltage and the output DC voltage of the killer circuit in the second color signal processing circuit for signal processing of the carrier color signal in the second color one-way color television signal; A switching DC voltage is applied to a switching terminal of a switching circuit that selectively switches and outputs one of the output signals of the first and second color signal processing circuits. Since the configuration is provided with a change-over switch for applying the same color, the change-over switch can be operated in advance according to the reception status of both the first color one-way type and the second color one-way color television signals. , without causing any malfunction to the switching circuit, automatically switching only the output signal of the first or second color signal processing circuit that is compatible with the color type of the selectively received color television signal from the switching circuit. In addition, there is no need to change the manual selection switch each time depending on whether the reception channel is color-only or not. It only needs to be operated once, so there is no need to perform any other operations, so the operability is improved compared to conventional manual television receivers that have a manual switch to prevent malfunction of the switching circuit. It is something that you have.

[Brief explanation of the drawing]

1 and 2 are block system diagrams showing each side of a conventional dual system color television receiver, respectively, and FIG. 3 is a block system diagram showing an embodiment of the dual system color television receiver according to the present invention. It is a diagram. 1...Carrier color signal input terminal, 2...P
AL color signal processing circuit, 3... SECAM color signal processing circuit, 6... Switching circuit, 9.11
・・・・・・Choice switch.

Claims (1)

[Scope of utility model registration request] An output signal of a first color signal processing circuit that processes a carrier color signal in a first color one-way color television signal; A dual-system color television that has a switching circuit that selects and passes only one of the output signals of a second color signal processing circuit that performs signal processing according to the switching DC voltage applied to the switching terminal. In the John receiver, the output DC voltage of the killer circuit in the first color signal processing circuit or the DC voltage related thereto;
Selectively transfer only one of the output DC voltage of the killer circuit in the second color signal processing circuit or the related DC voltage to the switching DC voltage to the switching terminal of the switching circuit. A dual-system color television receiver equipped with a changeover switch for applying the same voltage.