JPS58143684A - Color signal processing device of color recorded information reproducing device - Google Patents

Abstract

PURPOSE:To execute correctly the color demodulation in the scan mode of a video disc, by detecting the mutual inversion of the phase inverted state of a color burst signal of the PAL system to perform the PAL phase inversion. CONSTITUTION:A PAL color video signal is separated into a luminance signal and a chrominance signal by an LPF13 and a BPF14. The chrominance signal including the color burst signal is inputted to a PAL phase inverter 15. The burst signal is extracted from the chrominance signal. The burst signal has the polarity inverted at every 1H in a polarity inverter 19. This signal and a subcarrier signal are multiplied to demodulate the burst signal. A switch 17 is controlled by the demodulated signal to obtain a reproduced color burst waveform which is inverted with an accurate phase.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color signal processing device for reproducing color recorded information, and particularly to a PAL (Phase Alter-
The present invention relates to a color signal processing device for a reproducing apparatus that reproduces color recorded information using the nation line (Nation Line) method.

The PAL color signal Ep is Ep='y'+ (B-Y) sin ωst±(R-
Y)・COSωst (1) It is given by the following formula. Here, Y is the luminance signal.

B and R indicate blue and red signals, and ωS is the angular frequency of the color subcarrier, approximately 4.43 MHz.
It is. The symbol in equation (1) means phase inversion for each horizontal scanning line, and the R-Y component of the carrier color signal is 1
COS with 180” phase difference from each other for each horizontal scan line
The subcarrier signal ωst is AM-modulated and transmitted. To avoid this, the color burst signal must also serve as information for inverting the phase of the (RY) component subcarriers for each rice on the image receiving side. Therefore, as shown in the vector diagram in Figure 2, the color burst signal is switched line by line to a phase of ±135° around the B-Y axis, and the phase-inverted signal is sent out. There is.

FIG. 1 is a schematic block diagram of a receiver for demodulating such a PAL color video signal. The color video signal is separated into Y signal and C (chroma) by Y-C separator 1.
The C signal is input to a burst phase discriminator 2 and a carrier color signal separator 3. In the burst phase discriminator 2, the burst signal is extracted and sent to the subcarrier signal generator 4, and this burst signal sin (
A signal sinωS with an average phase of ωst±135°)
Subcarrier signal 5in with a 90° phase difference with respect to t
(ωst+90°)−COSωst is obtained. This generator 4 has a PLL (phase locked loop) circuit configuration, and is obtained using the output of a VCO (voltage controlled oscillator) within the PLL circuit.

This signal COSωSt serves as a single input for the switch 6 and is also input to the phase shifter 5. 9 in phase shifter 5
0° and 180° phase-shifted outputs are obtained, and the signal COSωst is phase-shifted by 90° to become sinωst, which becomes a subcarrier signal for detection by the synchronous detector 7. Further, the signal 180° phase-shifted, 1 aOSωst, is the output of the switch 6, and one of the COSωst signals selected by the switch 6 becomes a subcarrier signal for detection by the synchronous detector 8.

Each input of the synchronous detector 7.8 receives (B-Y) sin ωst and ±(R-Y
) cos mst signals are applied to the output of each detector 7.8 via LPFs 9 and 10.
B-Y) and (RY) signals. On the other hand, a synchronous separator 11 is provided to obtain a horizontal drive pulse, and the output of an FF (flip-flop) 12 triggered by this horizontal drive pulse serves as a switching signal for the switch 6. In addition, the burst phase discriminator 2
, it is detected whether or not the phase inversion state of the color burst signal is regularly made for each horizontal scanning period;
If this phase inversion state is reversed (1), the FF 12 is reset.

In other words, the PAL color signal is as described above.
Since the polarity of the carrier color signal component of RY) is reversed every horizontal scanning cycle, in order to perform correct color demodulation on the receiver side, it is necessary to determine the phase inversion state of the color 4\st signal. (R-
It is necessary to always invert the polarity of the subcarrier signal of the Y) component in a constant direction every horizontal scanning period. Therefore,
The burst phase discriminator 2 discriminates the phase inversion state of this color burst, and when the subcarrier signal inversion operation by the switch 6 is reversed and demodulating -(RY), the FFI 2 is reset; From then on, powerful demodulation begins.

However, if the response of the burst phase discriminator 2 is made faster, if noise is superimposed on the input color video signal, an erroneous set pulse will be generated in response to this noise, which is undesirable. Therefore, it is common practice to set a certain time constant so that a reset pulse is generated only when an incorrect l1111 is performed during the period, thereby making it resistant to noise. In this way, the method of providing a time constant is effective when receiving television broadcast waves, but when a video disc on which color video information is recorded is played back using a VDP (video disc player), this playback output is When using the above-mentioned receiver by inputting it, the following drawbacks occur. In other words, in the vDP, a so-called tracking servo device is added to ensure that the pickup information detection point always accurately tracks the recording track. There is a so-called scan mode in which information is searched for by sending it in the radial direction of the recording disk. During this scan mode operation, the tracking servo loop is on as described above, so the pickup information detection point tracks the recording track for a certain period of time and reads information, but the pickup detection point is biased. For example, when the tracking mirror reaches the movable eye field, it bounces back to the other limit position of the movable range and repeats the operation of tracking the information detection point along the recording track from that position again.

The so-called CAV (C
instant Anular Velocit
y) system, the horizontal synchronizing signal recording sections are aligned on the same radius line, so the rotation servo system of the recording disk is not disturbed depending on the scan mode, so the subcarrier signal generator 4 PLL
Since the phase pull-in of the burst lock oscillator (VCO) of the circuit is good, the PLL is sufficiently controlled within the track jumping operation ll11 field of the pickup detection point mentioned above.
locks. The problem here is that the number of interlaced tracks at the time of interlacing is not constant but unspecified, so the phase inversion state of the color burst signal before and after it is
There is a possibility that the situation can be reversed as shown in the figure.

In this state, as mentioned above, the response of the burst phase discriminator 2 shown in FIG. The color reproduction of time becomes unsightly.

Therefore, it is an object of the present invention to provide a color signal processing device for a color recorded information reproducing apparatus, which enables color demodulation of a receiver to always be performed correctly in scan mode without making any modifications to the existing receiver. The goal is to provide the following.

The color signal processing @ of the PAL type color recorded information reproducing apparatus according to the present invention detects that the phase inversion states of the reproduced color burst signals before and after the track skip in the scan mode are mutually reversed. The present invention is characterized in that the PAL phase inversion of the reproduced signal ((RY) COS ωS of the color burst signal and the carrier color signal) is forcibly performed.

The present invention will be explained below with reference to the drawings.

FIG. 4 is a block diagram of an embodiment of the present invention, in which a reproduced RF (6 frequencies) signal from a recording disk is converted into a PAL color video signal by a detector (not shown), and a luminance signal and carrier color signal are converted by an LPF 13 and a BPF 14. signals (including color burst signals). The 4.43 MHz carrier color signal containing the color burst signal is input to the PAL phase inverter 15 . This phase inverter 15 uses, for example, a well-known heterodyne conversion method, and is composed of a multiplier 151 and a BPF 152. In the multiplier 151, the output from the multiplier 16, that is, the signal Co52ωst, is multiplied by the carrier color signal. , only the fundamental wave component (ωS) of the beam frame result is selectively derived by the BPF 152 and becomes the single-manpower switch 17. The output of the 8PF14 is directly applied to the other inputs of the switch 17.

The output of the BPF 14 is input to the burst gate 18, where the burst signal (b+) is extracted and applied to the polarity inverter 19 and subcarrier signal generator 20 (which is a PLL circuit with the same configuration as circuit 4 in FIG. 1). will be done.Polarity reversal!1
19, the polarity inversion command signal (ω) having a period of 2H (H indicates one horizontal scanning period) is used to invert the polarity of the color burst signal every 1H. This output (C1 is the burst signal In the converter 21, the output COSωst of the subcarrier signal generator 20 is multiplied by the output COSωst, and the demodulated output (small) is applied to the zero level comparator 22. The output of the comparator 22 controls the switching of the switch 17. Its switching selection output (e)
is added to the luminance signal again in the adder 23, and the reproduced P
This serves as an input to the receiver shown in FIG. 1 as an AL color signal output.

5 and 6 are operation waveform diagrams of the blocks in FIG.
) to +e+ are shown, respectively. FIG. 5 shows a case where the phase inversion state of the color burst signal (b) every 1H is normal, and in the polarity inverter 19, the color burst signal every 1H having a phase of -135° is inverted in the second As shown by the vector indicated by the dotted line in the figure, the polarity is inverted and a signal with a phase of +45° is obtained. Therefore, the output signal (C) of the inverter 19
is sih (ωst+135°) and sin
A signal of (ωst+45°) will appear every day. In the burst demodulator 21, this output signal (0)
and the output signal COSωst of the subcarrier signal generator 20
Since only the low frequency components are derived, the 11M output (small is a waveform with a positive level as shown in FIG. 5).

This is clear from the calculation formula below. In other words, sin (ωst+135”) −cos ωs
t= 1 /2−(sin (2ωst+ 135°
) +sin 135' )・・・・・・(2) Sin ((iJ St+ 45°)φCO8ω5t
=1/2・(sin (2ωst+45°) +si
n 45°) (3) Therefore, both DC components are positive. Therefore, the output of the zero level comparator 22 generates a high level control signal to cause the switch 17 to select the output of the BPF 14 as it is. Therefore, P.A.
PAL in correct phase state without L phase inversion
A color reproduction video signal is introduced to the receiver.

Next, when the phase inversion state of the reproduced color burst signal is opposite to that shown in FIG. 5(b), the waveform becomes as shown in FIG. 6. The output from the polarity inverter 19 is as shown in Figure (C), sin (ωst -135°) and sin (-
45") is obtained. In this case, the output of the burst demodulator 21 has negative polarity as shown in (d). That is, sin (ωst -135") - cos ωs
t= 1/2-(8in (2ωSt-135°
)+sin (-135”))・・・・・・(4
) sin (ω5t-45') -cos ωst
-1/ 2-(sin ()ω5t-45°)+si
n (-45°)) (5) This is because both DC components are negative.

Therefore, the output of the level comparator 22 becomes a low level, and the switch 17 is controlled to select the output of the PAL phase inverter 15. To explain the PAL phase inverter 15, if the carrier color signal including the color burst signal is sin (ωst+φ), the output of the multiplier 151 is cos 2ω5t-stn (ωat+φ)-1/2
−(sin (3ωst+φ) +Sin ((i
Jst-φ))...(6) Only the fundamental wave component is extracted by the BPF 152, and the sin (ωSt-φ) component is obtained. Here, since the BY component of the carrier color signal has φ=0 (see FIG. 2), the output of the BPF 152 becomes sinωst and is not subjected to phase inversion. Similarly, the R-Y component is φ-π/
2, the output of BPF152 is Sin (ω5t
-7 (/2), and undergoes phase inversion with respect to input 5 inches (ωst +π/2). Also, since the color burst signal is φ=±135°, the input sin (ωst±1
35°), the output of BPFI52 is sin (ωs
t 135') and similarly undergoes phase inversion. Therefore, it can be seen that PAL phase inversion is possible.

It goes without saying that the PAL phase inverter 15 may be of the glass delay line type instead of the heterodyne conversion type of this example. From the above, the reproduced color burst waveform in this case becomes as shown in FIG. 6(e), and is correctly controlled to be in the same inverted state as in FIG. 5+e> and sent to the receiver.

As described above, according to the present invention, color reproduction can be performed correctly in scan mode or still image playback by simply adding a simple circuit to the regenerator, so existing receivers can be used as they are without any modification. It is convenient because it can be used as a playback monitor for VDP.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a color signal processing circuit of a PAL color receiver, FIG. 2 is a vector diagram of a color carrier signal, and FIG. 3 is a diagram explaining the phase state of a color burst signal in VDP scan mode. FIG. 4 is a block diagram of an embodiment of the present invention, and FIGS. 5 and 6 are operation waveform diagrams of the blocks in FIG. 4. Explanation of symbols of main parts 15...PAL phase inverter 17...Switch 18...Polarity inverter 20 for burst gate 19...Sub Carrier signal generator 21...
...burst ll1i device

Claims (1)

[Scope of Claims] 1) Color signal processing v41f of a color recorded information reproducing apparatus according to the PAL system in which one of the carrier color signals and a color burst signal are recorded with phase inversion every one horizontal scanning period, detecting that the phase inversion states of the reproduced color burst signals before and after the period are reversed, and phase inverts one of the reproduced carrier color signals and the reproduced color burst 1~ signal; A color signal processing device characterized by: 2) polarity inversion means for inverting the polarity of the reproduced color burst signal every horizontal scanning period, and multiplying the output signal of the polarity inversion means by a signal having the same phase and frequency as one subcarrier of the carrier color signal; 2. The apparatus according to claim 1, further comprising means for obtaining a low-frequency component thereof, and wherein phase inversion control of the carrier color signal is performed using the low-frequency component.