JP2552307Y2 - PAL / SECAM switching modulator - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PAL / SECAM switching modulator, and more particularly to a VTR (video deck) modulator which is applied to a PAL system and a SECAM system.

FIG. 3 shows a block diagram of an example of the prior art. In the figure, 1
Is a PAL dedicated IC, which comprises a clamp circuit 2, a clip circuit 3, an amplifier 4 (above, a video signal system), an amplifier 5, and an FM modulation oscillation circuit 6 (above, an audio signal system). Terminal 8
The video signal which has entered the video signal is mixed with the following audio signal via the clamp circuit 2, the clip circuit 3, and the amplifier 4.
When applied to the PAL system, connects the switch SW ₁ to SW ₄ to each terminal P side. The audio signal input to the terminal 10 is subjected to FM modulation by the FM modulation oscillation circuit 6 through the emphasis circuit 11 and mixed with the video signal through the amplifier 5 and the switches SW ₃ and SW _4. Is subjected to negative balanced modulation by a balanced modulator 9, extracted by an output terminal 12 and supplied to a television receiver. At the time of FM modulation, the FM modulation oscillation circuit 6 tunes and oscillates at the output of the tuning circuit 13, and uses this oscillation frequency signal as a carrier wave as an audio signal.
Modulate.

On the other hand, when applied to the SECAM system, the switch SW ₁ to SW ₄
Are connected to the terminals SW respectively. Audio signal AM modulator 15 which is incoming to the terminal 10, the ceramic filter 16, is mixed with the video signal via the switch SW _4, multiplied by the positive balanced modulation by balanced modulator 9, it is discharged from the output terminal 12 . At the time of AM modulation, the FM modulation oscillation circuit 6 tunes to the output of the tuning circuit 18 and oscillates.
It is supplied to the AM modulator 15 as a carrier wave through a switch SW _3.

Problems to be solved by the present invention In the conventional modulator, IC1 is exclusively for PAL,
The SECAM type AM modulator 15 is provided outside the IC 1,
The switch SW ₁ to SW ₄ in addition to this, such as the tuning circuit 13 and 18 is provided on the outside of the IC1. Further, the provision of the AM modulator 15 outside the IC 1 increases the pattern length and makes it easy for noise to be mixed in. Therefore, a ceramic filter 16 for suppressing high-frequency sound is required to prevent this. As described above, the conventional modulator requires a large number of external components provided outside the IC.

Therefore, if it is attempted to manufacture a modulator in which a tuning circuit is added to each of the circuit elements shown in the block diagram of FIG. It is not possible to use a printed circuit board with a compatible modulator, requires a relatively large printed circuit board, and the case outer dimensions are, for example, 44 mm
It is about × 62 mm, so that a new printed circuit board mold has to be designed, and there is a problem that it cannot be configured at low cost.

It is an object of the present invention to provide a PAL / SECAM switching modulator that can be used on the same small printed circuit board in up to four countries, and that can be made compact and low-cost.

Means for Solving the Problems The present invention relates to a PAL / SECAM switching module for selectively modulating a PAL or SECAM modulation method with a PAL or SECAM input video signal and an input audio signal, wherein the PAL input sound is A signal is supplied, an FM modulation oscillation circuit that performs FM modulation according to the PAL input audio signal, and an AM modulator that is supplied with the SECAM input audio signal and performs AM modulation according to the SECAM input audio signal An oscillation circuit for SECAM that supplies a carrier to the AM modulator; a switch circuit for switching the operation of the FM modulation oscillation circuit and the operation of the SECAM oscillation circuit according to a switching signal; and for the PAL or SECAM. An input video signal is supplied,
A video signal processing circuit for controlling the amplitude of an input video signal for PAL or SECAM is configured in one IC, and as an external component of the IC, connected to the FM modulation oscillation circuit, A PAL tuning circuit for tuning the circuit; a SECAM tuning circuit connected to the SECAM oscillation circuit for tuning the SECAM oscillation circuit; and a PAL input audio signal supplied to the PAL input audio signal. An emphasis circuit that applies emphasis to a signal and supplies the FM modulation oscillation circuit to the FM modulation oscillation circuit; and switches to supply the PAL input audio signal to the emphasis circuit when PAL is selected.
A switch for switching an input audio signal for ECAM so as to be supplied to the AM modulator; and an output modulated audio signal of the AM modulator or the FM modulation oscillation circuit and an output video signal of the video signal processing circuit are supplied. A balanced modulator that outputs a balanced modulated signal; an oscillation circuit that supplies a carrier to the balanced modulator; and a volume that switches between positive and negative balanced modulation according to the PAL or SECAM modulation method. Become.

Function In the present invention, the AM modulator is provided in the IC, so that the pattern length can be shortened compared to the conventional example in which the AM modulator is an external component of the IC. There is no need to provide such a ceramic filter as an external component of the IC, and the number of switches can be reduced. Therefore, the number of IC external parts can be reduced, so that the printed circuit board can be made smaller than the conventional example, and the same printed circuit board mold can be used for a modulator corresponding to up to four countries. Can be configured at low cost.

Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 1, reference numeral 20 denotes a PAL / SECAM IC, which is a clamp circuit 2, a clip circuit 3, an amplifier 4, (above, a video signal system), an AM modulator 21, an FM modulation oscillation circuit 6, and an oscillation circuit.
22, amplifier 24, switch circuit 25 (above, audio signal system)
, And constitute a main part of the present invention. Outside the IC 20, a switch SW ₁ , an emphasis circuit 11, a tuning circuit 13,
18 and so on are provided.

When applied to the PAL system, the connecting switches SW ₁ to the terminal P side, and supplies the oscillation operation switching control signal for FM modulation terminal 26. The audio signal input to the terminal 10 is subjected to FM modulation by the FM modulation oscillation circuit 6 through the emphasis circuit 11,
The signal is supplied to the balanced modulator 9 via the amplifier 24. At the time of FM modulation, the FM modulation oscillation circuit 6 is activated by the FM modulation oscillation operation switching control signal switched and output from the switch circuit 25, and is tuned by the output of the tuning circuit 13 to oscillate.

On the other hand, when applying to the SECAM system, switch SW _{1 is connected} to terminal S
Side, and supplies an oscillation control switch signal for AM modulation to a terminal 26. The audio signal input to the terminal 10 is subjected to AM modulation by the AM modulator 21 and supplied to the balanced modulator 9 via the amplifier 24. At the time of AM modulation, the oscillation circuit 22 is activated by the oscillation operation switching signal for AM modulation output from the switch circuit 25 and is tuned by the output of the tuning circuit 18 to oscillate.

In the present invention, the AM modulator 21 for the SECAM system, P
Since the FM modulation oscillation circuit 6, oscillation circuit 22, switch circuit 25, and the like for the AL system are provided in the IC 20, the number of IC external parts can be reduced. In this case, in particular, since the AM modulator 21 is provided inside the IC 20, the pattern length can be shortened as compared with the conventional example in which the AM modulator is configured as an external component of the IC, thereby reducing noise contamination. There is no need to provide the ceramic filter 16 for suppressing high-frequency sound as in the conventional example as an external component of the IC, and it is not necessary to provide the switches SW ₃ and SW ₄ as in the conventional example.

Therefore, if the same printed circuit board as that of the conventional example (corresponding to two countries) shown in FIG.
A tuning circuit for another one or two countries corresponding to the system can be provided. That is, as shown in FIG.
Four (four countries) tuning circuits 13, 18, 27, 28, etc. in a case 32 with external dimensions of about 44 mm (capacity is 30 cc) can be incorporated, and for three countries or four countries Case dimensions using a conventional printed circuit board (44mm x 60m
m), the same printed circuit board mold can be used for modulators corresponding to up to four countries, and the cost can be reduced compared to the conventional example. In this case, the tuning circuit 18
Is for the SECAM system, and the tuning circuits 13, 27 and 28 are for PAL. In FIG. 2, reference numeral 30 denotes a volume for switching between positive and negative balanced modulation schemes according to PAL / SECAM, and reference numeral 31 denotes a booster. The volume 30 is connected to the balanced modulator 9, and the voltage supplied to the balanced modulator 9 is controlled by rotating the volume 30. The voltage is set according to the rotational position of the volume 30.

The polarity to be modulated by the balanced modulator 9 is determined according to the voltage controlled by the volume 30. The balanced modulator 9 is
When the voltage supplied from the volume 30 is higher than a predetermined level, modulation is performed with a positive polarity, and the SECAM modulation method is performed. When the voltage supplied from the volume 30 is lower than a predetermined level, modulation is performed with a negative polarity. Is performed, and the PAL modulation method is performed. Also, switch SW ₁ and tuning circuits 13, 27, 28
Is provided on the back surface of the printed circuit board and is not shown in FIG.

Effect of the Invention As described above, according to the present invention, an audio signal FM modulation oscillation circuit for PAL, an audio signal AM modulator for SECAM,
A SECAM oscillation circuit for supplying a carrier to the AM modulator, a switch circuit for switching between the PAL FM modulation oscillation circuit and the SECAM oscillation circuit by an external PAL / SECAM switching signal, and a video signal system. By constructing the circuit and one IC, the conventional external AM modulator is built into the IC, and the PAL tuning circuit and SECAM tuning circuit can be directly connected to the IC without using a switch etc. Therefore, the number of external components can be reduced, so that the printed circuit board can be made smaller than before, and, for example, a modulator corresponding to up to four countries can be realized with the same printed circuit board mold.
It can be configured at lower cost than before.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a schematic plan view of one embodiment of the present invention, and FIG. 3 is a block diagram of an example of the related art. 6 FM modulation oscillator circuit, 9 balanced modulator, 10 audio signal input terminal, 11 emphasis circuit, 12 output terminal, 13, 18,
27, 28: tuning circuit, 14: oscillation circuit, 20: PAL / SECAM I
C, 21: AM modulator, 22: oscillation circuit, 25: switch circuit, 2
6… Oscillation operation switching control signal input terminal, 31… Booster, 32
… Case, SW ₁ … Switch.

Claims (1)

(57) [Scope of request for utility model registration] 1. A PAL / SECAM switching module for selectively modulating a PAL or SECAM modulation method by a PAL or SECAM input video signal and an input audio signal, wherein the PAL input audio signal is supplied, An FM modulation oscillating circuit that performs FM modulation in accordance with an input audio signal for PAL; an AM modulator to which the input audio signal for SECAM is supplied and performs AM modulation in accordance with the input audio signal for SECAM; and the AM modulator A SECAM oscillation circuit for supplying a carrier to the PAL or SECAM input video signal; a switch circuit for switching the operation of the FM modulation oscillation circuit and the operation of the SECAM oscillation circuit according to a switching signal. , Said PA
A video signal processing circuit for controlling the amplitude of the input video signal for L or SECAM is configured in one IC, and connected to the FM modulation oscillation circuit as an external component of the IC, and the FM modulation oscillation A PAL tuning circuit for tuning the circuit; a SECAM tuning circuit connected to the SECAM oscillation circuit for tuning the SECAM oscillation circuit; and a PAL input audio signal supplied to the PAL input audio signal. An emphasis circuit for applying an emphasis to a signal to supply the FM modulation oscillation circuit, and a PAL input audio signal is switched to be supplied to the emphasis circuit when PAL is selected, and the SEC is selected when SECAM is selected.
A switch for switching an AM input audio signal to be supplied to the AM modulator; and an output modulator audio signal of the AM modulator or the FM modulation oscillation circuit and an output video signal of the video signal processing circuit are supplied. A balanced modulator that outputs a balanced modulated signal; an oscillation circuit that supplies a carrier to the balanced modulator; and a volume that switches between positive and negative balanced modulation according to the PAL or SECAM modulation method. Naru PAL / SECAM
Switching module.