JPH09154153A - Video signal processing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the processing unit by which a color signal is reproduced in a television receiver of the PAL system in the case of reception of an NTSC system composite video signal when a video tape recorder of the PAL system is stopped. SOLUTION: A carrier circuit 11 outputs a signal whose frequency is expressed as 2 fSC+(27+9/64}fH}, where fSC is a subcarrier frequency of the NTSC system and fH is a horizontal scanning frequency, and balanced-modulated with an NTSC system carrier chrominance signal from a 1st BPF 6 and a 1st balanced modulator BM8 to convert the frequency of the signal outputted from the carrier circuit 11. An output of the 1st modulator BM8 is given to a 2nd BPF 9, in which an undesired component is eliminated, the result is given to a system converter 10, where the signal is converted into the PAL system carrier chrominance signal, it is added to a luminance signal extracted from the 1st LPF 3 at an adder 4, then a composite video signal whose carrier chrominance signal is converted into the PAL system is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PAL video tape recorder for converting an NTSC video signal into a P video signal.
The present invention relates to a video signal processing device for converting an AL system video signal.

[0002]

2. Description of the Related Art In recent years, in a video signal processing device of a PAL video tape recorder, not only recording and reproduction of a PAL video signal but also recording and N.C.
When playing a video tape recorded in the TSC system, P
It is becoming more common to have a function of converting to an AL system video signal.

A video signal processing device of a conventional PAL video tape recorder will be described below.

FIG. 5 and FIG. 7 are block diagrams of a video signal processing device of a conventional PAL system video tape recorder at the time of recording, stopping and reproducing, respectively.

In FIG. 5, reference numeral 1 indicates the input of the input composite video signal.
Input terminal 2 is automatic gain control that keeps the amplitude of the luminance signal constant.
Circuit (hereinafter abbreviated as AGC) 3 is a composite video signal
The first process for extracting the luminance signal by removing the carrier color signal from the
-Pass filter (hereinafter abbreviated as LPF), 5 is a TE
Output terminal to revision, 6 is a composite video signal to luminance signal
Bandpass filter that removes the signal and extracts the carrier color signal
(Hereinafter, abbreviated as BPF), 7 is the amplitude of the carrier color signal.
Automatic gain control circuit for keeping constant (hereinafter abbreviated as ACC)
You. ), 8 are first balanced modulators (hereinafter abbreviated as BM)
You. ), 12 are phases of ACC7 and voltage controlled crystal oscillator 1
Phase that outputs the phase comparison error signal by comparing with the phase of 4
Comparator, 13 is the phase comparison output from the phase comparator 12.
Fourth LPF for smoothing error signal, 14 is fourth LPF
Voltage controlled crystal oscillator controlled by 13 (hereinafter referred to as VXO
Abbreviated. ) And 15 are voltage controlled oscillators (hereinafter referred to as VCO
Abbreviated. ), 16 from the output oscillation frequency of the VCO 15
 1/2 f_HIs a subtracter for subtracting
The first frequency divider for dividing the force signal by 1/4, 18 is 2
f _sc’+ 40f_H'And 40f_H'Outputs two frequency signals
The second BM, 19 that does
40f_H'Of the second LPF, 20 is the second
The second component that divides the output signal of the LPF 19 of
A frequency divider, 21 is a horizontal sync from the output signal of the sync separation circuit 25.
A horizontal synchronizing circuit for producing a signal synchronized with only the signal, 22
Is the phase of the second frequency divider 20 and the phase of the horizontal synchronizing circuit 21.
A phase comparator for comparing and outputting an error signal, 23 is a phase ratio
Third LP for smoothing the error signal output from the comparator 22
F and 24 divide the output oscillation frequency of the VCO 15 by a quarter
Is the third frequency divider, 25 is the output signal of the first LPF3?
A sync separation circuit for separating the sync signal from the
A frequency modulator that frequency-modulates the output signal of F3 (hereinafter,
It is abbreviated as FM modulator. ), 29 is the output of the first BM8
Fifth LPF for extracting low-pass conversion color signal from signal, 30
Is the output signal of the FM modulator 28 and the output of the fifth LPF 29
An adder for adding the signal and the output 31 to the video head
Terminal.

Further, in FIG. 7, there are the following blocks in addition to the blocks common to FIG. 4 is an adder, 9 is a second BP
F and 10 are format converters (hereinafter abbreviated as Convert), 32 is an input terminal for a signal from the video head, and 33
Is a high-pass filter (hereinafter abbreviated as HPF) that extracts a luminance signal from a reproduction signal input from the input terminal 32, 34 is a limiter, and 35 is a frequency demodulator (hereinafter, F
Abbreviated as M demodulator. ), 36 is a sixth L for extracting the low-frequency conversion color signal from the reproduction signal input from the input terminal 32.
PFs and 37 are comb filters (hereinafter abbreviated as Comb) for removing adjacent crosstalk from the carrier color signal, and 3.
Reference numeral 8 is a phase comparator for comparing the phase of the VXO 14 and the phase of the second BPF 9.

Regarding the video signal processing device of the conventional PAL video tape recorder having the above-mentioned structure,
The operation will be described below.

First, regarding the operation at the time of recording and at the time of stop in FIG. 5, a PAL system composite video signal is inputted from the input terminal 1. This composite video signal is controlled by the AGC 2 so that the amplitude of the luminance signal is constant, and is output from the output terminal 5 to a television receiver (not shown). Also, AGC
In the second output composite video signal, the carrier color signal is removed and the luminance signal is extracted in the first LPF 3. The first LPF 3 has a frequency characteristic having a trap characteristic at about 4.43 MHz, which is a subcarrier frequency (hereinafter, abbreviated as f _sc ') of the PAL system in order to remove the carrier color signal. The output luminance signal of the first LPF 3 is FM-modulated by the FM modulator 28 and output to the adder 30. On the other hand, in the first BPF 6, the luminance signal is removed from the composite video signal,
The carrier color signal is extracted. At this time, the center frequency of the pass band of the first BPF 6 is about 4.43 MHz.
The output carrier color signal of the first BPF 6 is controlled by the ACC 7 so that the amplitude is constant, and is frequency-converted by the first BM 8. Further, the LPF 29 removes an unnecessary component generated at the time of frequency conversion, so that the low-frequency converted color signal is taken out and supplied to the adder 30. The adder 30 adds the FM-modulated luminance signal and the low-frequency converted color signal, and outputs the result to the output terminal 31.
Supply to The output signal from the output terminal 31 is recorded on the video tape via the head during recording. The phase comparator 12 compares the phase of the color burst signal of the output carrier color signal of the ACC 7 with the output signal of the VXO 14 equipped with a crystal having a variable oscillation range of f _sc ′. This phase comparison error signal is smoothed by the LPF 13 and controls the VXO 14. As a result, the oscillation frequency of the VXO 14 becomes f _sc . VCO15 is

[0009]

(Equation 3)

The frequency of is held in a variable range. VCO1 now
5 oscillation frequency,

[0011]

(Equation 4)

Assume that It is assumed that f _H 'is slightly deviated from f _H. The subtracter 16 subtracts 1 / 2f _H 'from the output oscillation frequency of the VCO 15. As a result, the subtractor 1
The output signal frequency of 6 is

[0013]

(Equation 5)

## EQU1 ## Further, by dividing the frequency by 1/4 by the first frequency divider 17, the output signal frequency becomes

[0015]

(Equation 6)

## EQU1 ## In the second BM18, VXO14
And the output signal of the first frequency divider 17 are balanced-modulated. As a result, from the second BM 18,

[0017]

(Equation 7)

Two frequency signals of 40 and 40f _H 'are output. The second LPF 19 removes the high frequency to extract the 40 f _H ′ signal. Next, the second frequency divider 2
The frequency is divided into 1/40 by 0, and the signal of f _H 'is output. By the way, the output luminance signal of the first LPF 3 is separated by the synchronization separation circuit 25. From this synchronizing signal, the horizontal synchronizing circuit 21 creates a signal synchronized only with the horizontal synchronizing signal. From this, the output signal frequency of this horizontal synchronizing circuit becomes f _H. The phase comparator 22 compares the phases of the output signal of the second frequency divider 20 and the output signal of the horizontal synchronizing circuit 21. As a result, the difference between f _H 'and f _H is output as an error signal from the phase comparator 22, and this error signal is smoothed by the third LPF 23 to control the VCO 15. From the above, the oscillation frequency of the VCO 15 is f _H '
And the difference between f _H is corrected,

[0019]

(Equation 8)

Will be controlled. The frequency is about 20.24 MHz. The third frequency divider 24 divides the output oscillation frequency of the VCO 15 into quarters. From this, the first BM carrier signal frequency is

[0021]

(Equation 9)

As a result, the subcarrier frequency of the low-frequency converted color signal output from the LPF 29 is VHS.PA.
This is a standard for L-type video tape recorders.

[0023]

(Equation 10)

## EQU1 ## Each of the blocks described above has a known content, but the operation of subtracting the frequency of the subtractor 16 is not general, and will be described with reference to FIG.

In FIG. 6, (a) and (b) are circuit diagrams of the subtractor 16, and (c) is a timing diagram of (b). Further, 26, 39, 40 are input terminals, 27, 4
1 is an output terminal. F6 and F7 are D-type flip-flops, G3 is an exclusive OR element, and G4 to G
Reference numeral 13 is an inverter element. The output signal of the second frequency divider 20 of FIG. 5 is input to the input terminal 26. This signal frequency is f _H, which is divided by the operation of F6 into a half frequency and output from the output terminal 27. Therefore, a signal of 1 / 2f _H is output from the output terminal 27. The output terminal 27 is connected to the input terminal 39. Input terminal 40
The output signal of the VCO 15 of FIG. F7
Then, the signal from the terminal 39 is latched at the falling timing of the terminal 40. G4 to G13 are for setting a delay amount equal to or larger than the delay amount required for F7 to rise or fall. As a result, the output signal of G3 delays the signal from the input terminal 40 by 180 degrees when the output signal of F7 rises and falls, as shown in the timing chart. That is, during one cycle of the output signal of F7, a signal obtained by subtracting one cycle from the signal from the input terminal 40 is output from the output terminal 41 via G3. This means that the frequency signal obtained by subtracting the frequency of F7 from the signal frequency of the input terminal 41 is output from the output terminal 41. Output signal frequency of F7 and input terminal 3
Since the signal frequencies input to 9 are the same, the frequency signal obtained by subtracting the input signal frequency of the input terminal 39 from the input signal frequency of the input terminal 40 is output from the output terminal 41. Since a 1/2 f _H signal is now input to the input terminal 39, the output oscillation frequency of the VCO 15 becomes 1 / f.
2f _H will be reduced.

Further, when a composite video signal of NTSC system is inputted from the input terminal 1, it is dealt with by switching each block as follows. First, the trap frequency of the first LPF 3 is set to about 3.58 MHz.
Next, the center frequency of the pass band of the first BPF 6 is set to about 3.
58 MHz. Furthermore, the VXO 14 switches to a crystal having f _sc (about 3.58 MHz) in the variable oscillation range. Also, the VCO 15

[0027]

[Equation 11]

The frequency (about 16.84 MHz) is switched so that it has a variable range. Finally, the function of the subtractor 16 is stopped.

[0029] The subcarrier frequency of the low frequency converted color signal by the above, it is possible to 40f _H is a standard VHS · NTSC system, the output terminal 31 can output a recording signal in accordance with the standards . At this time, the NTSC composite video signal is directly output from the output terminal 5.

Next, regarding the reproducing operation of FIG. 7, a case of reproducing a tape recorded by the PAL system will be described first. A reproduction signal reproduced from the tape is input from the input terminal 32 via the video head. In HPF33,
The low-frequency conversion color signal is removed, and the FM-modulated luminance signal is extracted. Next, the limiter 34 makes the amplitude constant, and the FM demodulator 35 demodulates it into a luminance signal. The first LPF 3 removes unnecessary components from the luminance signal, and the adder 4
Supplied to On the other hand, the LPF 36 removes the FM-modulated luminance signal and extracts the low-frequency converted color signal. The low-pass conversion color signal has a constant amplitude by ACC7,
The frequency is converted by the BM. In this frequency-converted signal, unnecessary components are removed by the first BPF having a pass band of about 4.43 MHz, and the carrier color signal is extracted. Comb 37 removes adjacent crosstalk from the carrier color signal. In recent years, the Comb is composed of a charge coupled device (hereinafter abbreviated as CCD). In the second BPF 9 whose pass band has a center frequency of about 4.43 MHz, unnecessary components such as a clock generated in the CCD are removed. The color burst signal of the carrier color signal output from the second BPF 9 is compared in phase by the phase comparator 38 with the signal from the VXO 14 oscillating at f _sc ′. This phase error signal is smoothed by the LPF 23 and controls the VCO 15. At this time, the oscillation frequency of the VCO 15 is (Equation 8)
Becomes The output oscillation frequency of the VCO 15 is halved by the third frequency divider 24,

[0031]

(Equation 12)

It becomes the output signal of and is supplied to the first BM 8. The subcarrier frequency of the low-frequency conversion color signal input to the first BM8 is

[0033]

(Equation 13)

Therefore, as a result, the output signal of the first BM 8 includes the carrier color signal whose subcarrier frequency is f _sc ′, and the second BPF 9 outputs the carrier color signal. In the case of the PAL system, the Convert 10 does not perform any processing and supplies it to the adder 4. In the adder 4, the luminance signal from the first LPF and the Converter
The carrier color signals of the PAL system passing through t10 are added and output as a PAL system composite video signal from the output terminal 5 to the television.

Next, the case of reproducing a tape recorded by the NTSC system will be described. The operation of each block is
Except for Convert10, it is almost the same as that of the PAL reproduction signal. However, since the subcarrier frequency of the low-frequency conversion color signal output from ACC7 is 40 f _H , the VCO
The oscillation frequency of 15 is (Equation 11). As a result, the output signal of the second BPF 9 becomes an NTSC carrier color signal having a subcarrier frequency of f _sc ′. In the Convert 10, the carrier color signal is converted into the PAL system and output. As a result, the carrier color signal from the adder 4 becomes PA.
The composite video signal converted into the L system is output and output from the output terminal 5 to the television. As a result, even when the television is the PAL system, it is possible to reproduce the tape recorded in the NTSC system and reproduce the color signal as well as the luminance signal on the television screen.

The operation of the Convert 10 will be described with reference to FIGS. 8 and 9. (A) of FIG. 8 is Conve
It is a block diagram of rt10. (B) is a waveform diagram of the output signal. FIG. 9 is a vector diagram of signals related to FIG. In FIG. 8A, 39 is an input terminal, 40 is an output terminal, 41 is a switch circuit, 42 is a control circuit, 43 is a DC voltage source, and 44 is a first phase shift that shifts the phase of an input signal by +45 degrees. And 45 is a second phase shifter for shifting the phase of the input signal by -45 degrees. A vector diagram of the NTSC system carrier color signal input to the input terminal 39 is shown in FIG. In FIG. 9A, e is a color burst signal and f is a color signal. The first phase shifter 44 shifts the phase of the signal from the input terminal 39 by +45 degrees. In the second phase shifter 45, the input terminal 3
The signal from 9 is shifted by -45 degrees. The output amplitudes of the first and second phase shifters 44 and 45 are half the input amplitude.

Now, let the signal at the input terminal 39 be a, the output signal of the first phase shifter 44 be b, the output signal of the second phase shifter 45 be c, and the output signal of the DC voltage source 43 be d. . The switch circuit 41 inputs and selects four signals a, b, c, and d, and outputs one of them to the output terminal 40. The selection is controlled by the control circuit 42. This control method will be described with reference to the waveform diagram of FIG.

First, the horizontal scanning period is divided into a color burst signal period and the other color signal periods, and the signal c, the signal a during the color signal period, and the next horizontal scanning during the color burst signal period of the first horizontal scanning period are divided. The signal b is selected in the color burst signal period of the signal period, and the signal d is selected in the color signal period, and the switch circuit 41 is controlled so that these are repeated. At this time, vector diagrams of the first horizontal scanning period and the next horizontal scanning period of the signal output from the switch circuit 41 are shown in (b) and (c) of FIG. 9, respectively. In (b), c is a color burst signal and a is a color signal. The amplitude of c is half that of the color burst signal e of the input signal, and the phase is shifted by -45 degrees. Further, a is the same as the color signal of the input signal. In (c), the amplitude of b is half that of the color burst signal e of the input signal, and the phase is +
It is shifted by 45 degrees. Since d is the output signal of the DC voltage source 43, it is located on the origin. This (b),
When (c) is alternately output, the PAL system television adds the signal of one horizontal period before to create a baseband chrominance signal, so that the amplitudes of the color burst signals, which are the reference of saturation, are c and b. And the color signal part is the sum of a and d. For this reason, the amplitude of the color signal is halved, but the amplitudes of the color burst signals c and b are half the amplitude of the original color burst signal. The amplitude ratio of can be secured. In this way, the NTSC carrier color signal whose subcarrier frequency is f _sc 'is converted into a PAL carrier color signal.

[0039]

However, in the above-mentioned conventional configuration, since the NTSC system video tape which has been recorded once is converted into the PAL system carrier color signal and outputted at the time of reproduction, the PAL system television. Although the color signal can be reproduced with, when the input signal is an NTSC composite video signal at the time of recording and at the time of stop, the composite video signal is output in the same format, so that the color signal can be reproduced by the PAL television. Had the problem that it could not be reproduced.

The present invention solves the above-mentioned conventional problems and provides a video tape recorder capable of reproducing a color signal in a PAL system television even when an input signal is an NTSC system composite video signal. The purpose is to do.

[0041]

In order to achieve this object, a video signal processing apparatus of the present invention comprises a first band pass filter for extracting a carrier color signal from an NTSC composite video signal and an NTSC system sub-filter. When the carrier frequency is f _sc and the horizontal scanning frequency is f _H ,

[0042]

[Equation 14]

A carrier circuit for producing the frequency signal of
A first balanced modulator that uses the output signal of the carrier circuit as a carrier signal to frequency-convert the output signal of the first bandpass filter, and the first balanced modulator that uses a PAL subcarrier frequency as a substantially center frequency. A second bandpass filter for removing unnecessary components from the output signal of
System converter for converting the output signal of the band pass filter of the above into a PAL system carrier color signal, a first low pass filter for extracting a luminance signal from the NTSC system composite video signal, and an output of the first low pass filter It has a configuration including an adder for adding and outputting the luminance signal and the PAL system carrier color signal output from the system converter.

With this configuration, it is possible to obtain a video tape recorder capable of reproducing a color signal in a PAL system television even when the input signal is an NTSC system composite video signal.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION A first bandpass filter for extracting a carrier color signal from a composite video signal of NTSC system, according to the first, third and fourth aspects of the present invention,
When the subcarrier frequency of the NTSC system is f _sc and the horizontal scanning frequency is f _H ,

[0046]

(Equation 15)

A carrier circuit for generating the frequency signal of
A first balanced modulator that uses the output signal of the carrier circuit as a carrier signal and frequency-converts the output signal of the first bandpass filter, and a subcarrier frequency of the PAL system as a substantially central frequency, and the first balanced A second bandpass filter for removing unnecessary components from the output signal of the modulator, a system converter for converting the output signal of the second bandpass filter into a carrier color signal of the PAL system, and the composite video of the NTSC system A first low-pass filter for extracting a luminance signal from the signal, and an adder for adding and outputting the output luminance signal of the first low-pass filter and the PAL system carrier color signal output from the system converter. Yes, NTSC
This has the effect of converting the carrier color signal of the system composite video signal into the carrier color signal of the PAL system.

According to a second aspect of the invention, the carrier circuit is

[0049]

(Equation 16)

A voltage-controlled oscillator having a variable range of a frequency of a predetermined integer multiple of, a subtracter for subtracting a frequency of a predetermined integer multiple of 9 / 64f _H from the output oscillation frequency of the voltage-controlled oscillator, and an output of the subtractor A first frequency divider for dividing the signal frequency by a predetermined integer, a crystal oscillator controlled to be phase-locked to the subcarrier frequency of the NTSC composite video signal, and an output signal of the crystal oscillator A second balanced modulator that balance-modulates the output signal of the first frequency divider; a second low-pass filter that extracts a frequency signal of 27f _H from the output signal of the second balanced modulator; A second frequency divider that divides the output signal frequency of the second low-pass filter into 1/27; a horizontal synchronizing circuit that creates a signal synchronized with the horizontal synchronizing signal from the synchronizing signal; and an output signal of the horizontal synchronizing circuit. The second A phase comparator that compares the phases of the output signals of the frequency divider and an output phase error signal of the phase comparator are smoothed, and the voltage controlled oscillator is controlled to have a frequency that is a predetermined integer multiple of (Equation 16). A third low-pass filter and a third frequency divider that divides the output signal frequency of the voltage controlled oscillator into a predetermined integral multiple of 1/2, which is a sub-carrier of an NTSC carrier color signal. Carrier frequency is PA
It has an effect of creating a carrier signal used for the BM for converting to the L-system subcarrier frequency.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a block diagram of a video signal processing device of a PAL video tape recorder when a composite video signal of the NTSC system of the present invention is input and is stopped.

In FIG. 1, the same components as those of the prior art are designated by the same reference numerals and the description thereof will be omitted. In addition,
Reference numeral 11 indicates a carrier circuit. Further, it is assumed that the recording is switched to the conventional block diagram shown in FIG. 5 at the time of stop when the PAL system composite video signal is input, and at the time of reproduction is switched to the conventional block diagram of FIG.

In FIG. 1, the difference from the conventional block diagram at the time of stop of FIG. 5 when an NTSC composite video signal is input to the input terminal 1 is that the operation of the carrier circuit 11 is
The output of the first BM is supplied to the second BPF, and Conv
The luminance signal from the first LPF is added by the adder 4 through the ert 10 and output from the output terminal 5 to the television. First, in the carrier circuit 11, the VCO
The oscillation frequency of 15 is

[0054]

[Equation 17]

It is controlled so that Therefore, the subtraction frequency in the subtractor 16 is 9 / 16f _H , and the output signal frequency is

[0056]

(Equation 18)

Is as follows. First frequency divider 17, phase comparator 1
2, the operation of the LPF 13, the VXO 14, the second BM 18, and the second LPF is the same as the conventional one, so the output signal frequency of the second LPF is 27f _H. In the second frequency divider 20, the 27f _H signal frequency is divided into 1/27 and f
Create an _H output signal. Since the operations of the horizontal synchronizing circuit 21, the phase comparator 22, and the third LPF are the same as those of the conventional one,
The oscillation frequency of the VCO 15 is

[0058]

[Equation 19]

Is as follows. The third frequency divider divides the output oscillation frequency of the VCO 15 by a factor of two, and thus the first BM8
The signal frequency output to is (Equation 20).

[0060]

(Equation 20)

Here, the operation of the subtracter 16 will be described with reference to FIG. 2A is a circuit diagram of a part of the subtractor 16, and FIG. 2B is a timing chart thereof.
In FIG. 2A, 26 is an input terminal for inputting the frequency signal of f _H from the second frequency divider 20, 27 is an output terminal, F1 to F5 are D type flip-flops, and G1 is an exclusive OR. The element, G2, is an inverter element. As shown in FIG. 2B, from the output terminal 27,
Since the output signal of 9 cycles is output during 16 cycles of the input signal of the terminal 26 whose frequency is f _H , the frequency is 9 /
It becomes 16f _H. When this signal is input to the input terminal 39 of the circuit diagram shown in FIG. 6B, the output signal of the VCO 15 input from the input terminal 40 is input from the output terminal 41 of FIG. From the frequency of 9/16
A frequency signal obtained by subtracting f _H is output.

The NTSC system carrier color signal output from the ACC 7 is expressed by the following equation.

[0063]

(Equation 21)

Now

[0065]

(Equation 22)

Then, the output signal of the third frequency divider 24 is expressed by the following equation.

[0067]

(Equation 23)

Here, ω _cr = 2πf _cr . First BM
The output signal of 8 is represented by the product of (Equation 21) and (Equation 22). As a result, the output signal of the first BM 8 is represented by the following (Equation 24).

[0069]

(Equation 24)

This signal has a high frequency component removed by the second BPF 9 whose center frequency in the pass band is about 4.43 MHz, and becomes a signal represented by the following formula.

[0071]

(Equation 25)

This signal is converted by the Convert 10 into a carrier color signal of the PAL system. The operation of the Convert 10 will be described with reference to FIGS.

The structure of the Convert 10 is the same as the block diagram shown in FIG. Figure 3 is Conv
It is a wave form diagram of the output signal of ert10. As shown in FIG. 3, the signals a, b, c, and d in FIG. 8A are sequentially changed to c, d, b, and d in the color burst signal period and the color signal period.
Control is performed so that selection is performed in the order of a. 4 (a) is a vector diagram of the input signal of the Convert 10 shown in (Equation 21), FIG. 4 (b) is a vector diagram of the first horizontal scanning period of the waveform diagram shown in FIG. 3, and FIG. FIG. 3C shows a vector diagram in the horizontal scanning period subsequent to the waveform diagram shown in FIG. When (b) and (c) of FIG. 4 are output alternately, P
In the AL system television, since the baseband color signal is created by adding the signal of one horizontal period before, the amplitude of the color burst signal which is the reference of the saturation is the sum of c and b, and the color signal part is a. And d are the sum. Therefore, although the amplitude of the color signal is halved, the color burst signal c,
Since the amplitude of b is half the amplitude of the original color burst signal, the amplitude ratio between the color burst signal and the color signal in the television can be secured. In this way, the carrier color signal of the PAL system in which the subcarrier frequency is (Equation 2) is converted. (Equation 2) is about 4.43 MH
z, which is within the range in which the phase can be locked in the PAL television, the color signal can be reproduced.
The PAL-system carrier color signal output from the Convert 10 is added to the luminance signal from the first LPF 3 by the adder 4 to form a PAL-system composite video signal, which is output from the output terminal 5 to the television.

As described above, according to the present embodiment, NT
First to extract carrier color signal from SC composite video signal
BPF 6, a carrier circuit 11 that creates a frequency signal of (Equation 1), a first BM 8 that frequency-converts the output signal of the first BPF 6 using the output signal of the carrier circuit 11 as a carrier signal, and the PAL system. The sub-carrier frequency of the first BM8 is substantially the center frequency, the second BPF 9 for removing unnecessary components from the output signal of the first BM8, and the Conve for converting the output signal of the second BPF 9 into the carrier color signal of the PAL system.
rt10, a first LPF3 for extracting a luminance signal from the NTSC composite video signal, and the first LPF3.
Output luminance signal of P and P output from Convert10
By providing the adder 4 for adding and outputting the AL system carrier color signal, when the NTSC system composite video signal is input when the PAL system video tape recorder is stopped, the carrier system color signal is transmitted. Since the carrier color signal can be converted and output, the color signal can be reproduced even in a PAL television. Further, the configuration can be easily configured because it is possible to change some connections of blocks that exist in the related art and some changes of some block functions.

[0075]

As described above, according to the present invention, when the composite video signal of the NTSC system is input when the PAL system video tape recorder is stopped, the carrier color signal of the composite video signal of the NTSC system is transmitted.
Since it can be converted into an L-type carrier color signal and output, the color signal can be reproduced even in a PAL-type television. In addition, the configuration can cope with a change in some connections of existing blocks and a slight change in some of the block functions, so that an excellent effect that the configuration can be easily achieved is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video signal processing device according to a first embodiment of the present invention.

FIG. 2A is a circuit diagram of the video signal processing device according to the first embodiment. FIG. 2B is a timing diagram of the video signal processing device according to the first embodiment.

FIG. 3 is a waveform diagram for explaining the operation of the video signal processing device according to the first embodiment of the present invention.

FIG. 4 is a vector diagram for explaining the operation of the video signal processing device according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a conventional video signal processing device during recording and when stopped.

6A is a circuit diagram of a main part of a conventional video signal processing device, FIG. 6B is a circuit diagram of a main part of a conventional video signal processing device, and FIG. 6C is a timing diagram of a conventional video signal processing device.

FIG. 7 is a block diagram of a conventional video signal processing device during reproduction.

FIG. 8A is a block diagram showing a configuration of a main part of a conventional video signal processing device during reproduction. FIG. 8B is a waveform diagram of a conventional video signal processing device during reproduction.

FIG. 9 is a vector diagram of a conventional video signal processing device during reproduction.

[Explanation of symbols]

 1 Input Terminal 2 AGC 3 1st LPF 4 Adder 5 Output Terminal 6 1st BPF 7 ACC 8 1st BM 9 2nd BPF 10 Convert 11 Carrier Circuit 12 Phase Comparator 13 LPF 14 VXO 15 VCO 16 Subtraction Device 17 First frequency divider 18 Second BM 19 Second LPF 20 Second frequency divider 21 Horizontal synchronizing circuit 22 Phase comparator 23 Third LPF 24 Third frequency divider 25 Synchronous separation circuit

Claims (4)

[Claims] 1. A first bandpass filter for extracting a carrier color signal from an NTSC composite video signal, and NTSC
The sub-carrier frequency of the system is f _sc and the horizontal scanning frequency is f _H
When, , A first balanced modulator that uses the output signal of the carrier circuit as a carrier signal to frequency-convert the output signal of the first bandpass filter, and a subcarrier frequency of the PAL system A second bandpass filter having a center frequency for removing unnecessary components from the output signal of the first balanced modulator, and a system converter for converting the output signal of the second bandpass filter into a carrier color signal of PAL system. A first low-pass filter for extracting a luminance signal from the composite video signal of the NTSC system, an output luminance signal of the first low-pass filter, and a PAL-system carrier color signal output from the system converter, An image signal processing device comprising: an adder for outputting. 2. The carrier circuit has: A voltage controlled oscillator having a variable range of a frequency which is a predetermined integral multiple of 9/64 from the output oscillation frequency of the voltage controlled oscillator
a subtractor for subtracting a frequency that is a predetermined integer multiple of f _H , and a first frequency divider that divides the output signal frequency of the subtractor by a predetermined integer
And a crystal oscillator controlled to be phase locked to the subcarrier frequency of the NTSC composite video signal,
A second balanced modulator that balance-modulates the output signal of the crystal oscillator and the output signal of the first frequency divider, and a second balance signal that extracts a frequency signal of 27f _H from the output signal of the second balanced modulator Low-pass filter, a second frequency divider that divides the output signal frequency of the second low-pass filter into 1/27, a horizontal synchronizing circuit that creates a signal synchronized from the synchronizing signal to the horizontal synchronizing signal, A phase comparator that performs phase comparison between the output signal of the horizontal synchronizing circuit and the output signal of the second frequency divider, and the output phase error signal of the phase comparator is smoothed, and the voltage controlled oscillator is A third low-pass filter for controlling the frequency to be a predetermined integer multiple, and the output signal frequency of the voltage controlled oscillator is a half of a predetermined integer.
2. The video signal processing device according to claim 1, wherein the video signal processing device comprises a third frequency divider that divides the frequency into a frequency signal of (3), and an output signal of the third frequency divider is output as a frequency signal of (Equation 1). . 3. The system converter includes a phase of an input signal of +45.
The phase of the input signal with the first phase shifter
A second phase shifter that shifts the input signal, an input signal, an output signal of the first phase shifter, an output signal of the second phase shifter, and four signals of a DC voltage source, and input one of them. The video signal processing device according to claim 1, further comprising a switch circuit for outputting and a control circuit for controlling the switch circuit, wherein the video signal processing device converts the carrier color signal into a PAL system. 4. A carrier color signal is extracted from a composite video signal of NTSC system, and when a subcarrier frequency of NTSC system is f _sc and a horizontal scanning frequency is f _H , a frequency signal of (Equation 1) is created, The carrier color signal is frequency-converted using the frequency signal as a carrier signal, an unnecessary component is removed from the frequency-converted signal with the subcarrier frequency of the PAL system being substantially the center frequency, and the carrier color signal of the PAL system is converted. Extracting luminance signal from NTSC composite video signal,
A video signal processing apparatus, wherein the luminance signal and the PAL system carrier color signal are added and output to convert the carrier color signal of the NTSC system composite video signal into a PAL system carrier color signal.