JPS60136493A - Chrominance signal processor - Google Patents

Abstract

PURPOSE:To allow demodulation of a low-band conversion chrominance signal digitally and to obtain a low-prices processor of a chrominance signal by preparing the demodulation axis of a low-band conversion chrominance signal by an A/D convertor circuit and a relatively simple digital circuit. CONSTITUTION:A low-band conversion chrominance signal (q) inputted from an input terminal 1 is A/D-converted in timing of a clock (b), and added to a code inverting circuit 6. The code inverting circuit 6 code-inverts only -P and -O parts out of A/D-converted output data (color-difference signal components P, O, -P and -O, provided that O is R-Y component and P is B-Y component) in timing of a code inverting pulse (f), and supplies them to latch circuits 7a and 7b. A phase of the code inverting pulse (f) advances by one clock at every hour when a field decision signal (i) is a logical value H, and delays by one clock when the decision signal (i) is a logical value L; therefore code inversion along a sampling demodulation axis is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for reproducing low frequency converted color signals recorded on a magnetic hoop in a rotary head type VTR or the like. Used as a removal method, the phase of the low-frequency conversion color signal is changed by 1 in the opposite direction in adjacent tracks (hereinafter referred to as △1 rack, 13 tracks).
A method in which PS processing is performed by shifting 90 degrees by 1- for every 1" (hereinafter referred to as PS method), and
- Invert the phase of the rack to 1Hfi3 1) Separate the low frequency conversion color signal recorded by jjffi (hereinafter referred to as 1) method) into two color difference signals m1ll-J
color signal processing)! This is related to the location.

Conventional configuration and problem A When recording and reproducing color video signals in a conventional rotary head type VTR, FM modulated lζ variable FJII
The luminance signal and the low frequency converted color signal converted to the low frequency carrier frequency fc are combined and recorded on the magnetic tape. In this case, in order to perform high-density recording without intervening a guard band between adjacent 1-racks, inclined azimuth recording is performed for modulated luminance signals, and for low-frequency conversion color signals, adjacent 1-racks are recorded. rack question
The PS method or the PI method-3 set is adopted so that the relationship of frequency interleaving can be established. As mentioned in 1 above, the low-pass converted color signal that has been subjected to I''S processing or PI processing returns its shifted or inverted phase to its original state during reproduction, and returns to its original high carrier frequency fsc (in the NTSC system). 3.58M
+-1,! ) It is necessary to convert the frequency to
The first method is to perform PS processing or PI processing in a circuit.
5I! 1111! A signal with a low carrier frequency fc is created, and the signal with the low carrier frequency fc and the frequency f
The standard signal of sa and the multiplication circuit are used to calculate the mold cylinder [c frequency fsc
+fc is created, and this frequency fsc +
The fc signal and the low frequency conversion color signal are multiplied by a multiplier circuit, and the carrier frequency is fsa+fc-fc=fs
There is a method to obtain a carrier color signal of c, but as a second method, the modulation axis of the low frequency conversion color signal is PS or PI5I! ll
[! Since it is considered to be a quadrature two-phase balanced modulated wave, the low-pass conversion color signal is demodulated into two -β color difference signals, and after demodulation, quadrature two-phase balanced modulation is performed using a carrier wave with a reference frequency fsc. It is also possible to obtain a carrier color signal of frequency fsa.

-4= 11. The first method is conventionally the most common method, but it requires two multiplication circuits, and it also requires two multiplication circuits to remove the upper sideband or lower sideband generated by multiplication. bandpass filters are required for each multiplier circuit,
The second method has the disadvantage of increasing the circuit scale, and the second method requires a low-frequency conversion fit (a circuit that creates a demodulation axis according to the PS method/PI method when demodulating the unevenness by inscribing it). A new circuit is required to perform VFI adjustment of the low frequency conversion color signal with reference to the demodulation axis.

OBJECTS OF THE INVENTION The present invention solves the drawbacks of the conventional methods described above, and when the second method is adopted as a method for reproducing low-frequency converted color signals, it The object of the present invention is to provide an inexpensive color signal processing device that is capable of creating a demodulation axis of a low-frequency conversion color signal and digitally demodulating the low-frequency conversion color f38.

Structure of the Invention In order to achieve the above objectives, the color signal processing-5- device of the present invention carries out low-frequency conversion color signals that have been subjected to phase shift and phase inversion processing. 1 non-pull hold and analog [1
A converting means for digital conversion, and a sign-inverted pulse J having the same frequency and phase synchronization as the low-frequency conversion burst based on the horizontal synchronizing pulse J, and) and r- field discrimination signal from the clock. pulse generating means for generating a color difference signal separation pulse having a frequency twice that of , and processing means for performing sign inversion and separation of the digital output from the conversion means using the sign inversion pulse and the color difference signal separation pulse. , l:,), which is configured to extract two color difference signal data by 1q from the low frequency converted color signal.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows how a low frequency converted color signal that has been subjected to PS processing according to an embodiment of the present invention is divided into two color difference signal data.
11 The circuit block diagram of the color signal processing device, Figure 2 is the low-frequency conversion urgent signal supplied to the circuit in Figure 1. In the circuit shown in Figure 1 (X
1 is a diagram of signal waveforms at various parts.

In Fig. 1, 1 is the input terminal to which the low-pass conversion color 4*j': Q is input, 2 is the input terminal for four times the low-pass conversion carrier frequency [1 b) is the input terminal for manual input, and 3) is the input terminal for inputting Δi. - Logical value 1 for rack and 81-rack, [field size >3' where [is reversed, l input @i is input manually, 4 is water sr,
This is the terminal to which the r synchronization pulse i1 is input. First, the low frequency conversion color signal q inputted from the input terminal 1 is inputted from the input terminal 2 by the A/D converter 5, and is subjected to an all-log digital conversion at the timing of lock 1). As shown in Fig. 2, the low-pass conversion color signal q has a phase of 90゛ in terms of the vector I~, and the 1'<-'l' component (), etc. of the color difference signal has a phase of 90゛ in vector I~. For example, h is generated by a PLL circuit from a horizontal synchronizing pulse h and a low-frequency conversion burst, and is shown in the timing shown in Fig. 3 in a steady state.
The A/D conversion output data C is the color difference signal components p, O, -p.
, -0 repeated data is 4-11 times. Next, the converted AD conversion output data C is
Sign inversion circuit 6 = 7 - J, 70 j3 At the timing of inversion pulse f, J, resotor -p, sign inversion is performed only at -o part,
The AD conversion data consists of repeated data of p and 0. The sign-inverted pulse f is obtained by dividing the clock b by 4 using the frequency divider 9, and then using the shift register 10 to create 4-phase pulses shifted by 1 clock.
It can be obtained by switching λ to 111 and outputting it.

The sign inversion pulse f is switched on the first rising edge of the horizontal synchronizing pulse h.
5 down, field discrimination signal @i flip-flop 1
1 to create a latched signal j, and use the signal j to switch the up/down operation of an up/down counter 12 that counts horizontal synchronizing pulses h.
This is done using the outputs Q4 and Qβ of 2. J to the above circuit configuration
:S, the sign inversion pulse f is) -f- When the field discrimination signal i is a logic value H, the phase advances by one clock of the clock b every day, and when the field discrimination signal i is a logic value 1, the phase advances by 11.
”, the sampling time will be delayed by one clock every time
An extreme sign inversion is performed on the i-key axis. Further, the sign-inverted pulse f is delayed by 1 [l] of the free 8-block flop 14 and the reflock 1). : Signal and exclusive OR circuit 1; J to i:
An exclusive OR is created. Flipf [1 tube 1G
latches the output of the exclusive OR circuit 15 and holds the two color X signal data d 1 and d 2 in the 0th order.
, color difference signal separation pulse Q1. The A/D conversion data 1 (passed through the sign inversion circuit 6) are latched by the latch circuits 7a and 7b based on the color difference a@separation pulse 01.(12). It is separated into two color difference signal data d1 and d2.This color difference signal data d
1 and d2 have the other color difference signal data due to timing, so in the end they are
Elb further applies a latch, and the color difference signal data e j , (
! It is set at 2.

In the waveforms of each part in FIG.
1) and the timing of the burst period (2F] that begins the next horizontal period. The phase of the low-pass conversion color signal q is shifted by 90° between the 11th and 21st days due to PS processing, and the phase of the low-pass conversion burst r is similarly shifted. are doing. Also, since the two color difference signal data e1 and 82 are obtained at 2rc, which is twice the low frequency carrier frequency fa, one color difference signal data is 1F4th and 21-1st based on the horizontal synchronization pulse h. “
The embedding point is 180°, the vertical phase shift is 1~, and the data h<
Cover with discontinuity. Therefore, in the circuit of this embodiment, the data of the previous sampling point is interpolated as the intermediate data of the sampling point using a zero-order hold filter, so that each color difference signal data is continuous and per 1F-1. It is assumed that the data output timing is aligned, making it easier to perform subsequent processing.

In the above explanation, the low-frequency conversion color signal q that has been subjected to PS processing is
We have described the case where the color difference signal is separated into two color difference signal data (!l, e2, but when dealing with a low-pass converted color signal that has been subjected to p+ processing, for example, as shown in Fig. 4, the method shown in Fig. 1) Shift 1 to register 10 are replaced with an inverter 17 that outputs two pulses: the quarter-frequency wave of lock b and its inverted output, and the up/down counter 12 is replaced with a frequency divider of 70 flips and 18. Furthermore, the output signal j of the flip-flop 11 becomes logic 1.
"11-Horizontal direction II which enters the tarok input of the fringe block 18 that creates a frequency-divided wave of the horizontal synchronizing pulse h"
By adding an AND circuit 19 that inhibits the pulse h, and operating the sign-inverted pulse f every 111 times using the field discrimination signal i, or outputting it continuously as it is, a color difference signal similar to that in PSS processing can be generated. data 01,
02 is reduced by 1q. Note that 20 is a data selector.

In addition, in P■ processing, the low carrier frequency is set to an odd multiple of 1/4 of the horizontal synchronization frequency 1H, and as in the case of PS processing, the 1H and 2) are based on the horizontal synchronization pulse h. The sampling point has a 180° phase shift between 1 and the eye.
However, since the frequency ringing becomes discontinuous, data in the middle of the sampling points is interpolated using zero-order hold, and the sampling frequency fs of the color difference signal data is set to 4 of the low carrier frequency fc.
It is converted into data that is continuous at multiples of -11- and is an integer multiple of fl,I. In addition, as in the case of recording and reproducing using the carrier color signals PS and Pr of the NTSC system, the above shows 11" correlated low-frequency conversion colors (
I have described the case of issue i, but if there is a two-day correlation between PAI one-way j;
The sampling R:1 wave number of each color difference signal data after interpolating the data between the sampling points is 4 times the low carrier frequency and an odd multiple of [1,l/2, and the data per 21-1 The output timings of the two can be aligned.

In order to obtain a carrier color signal with a carrier frequency fsc using the color signal processing circuit configured as described above, two color difference signal data are converted into analog data using a D/A converter, and then quadrature two-phase balanced barometric Alternatively, the obtained color difference signal data may be converted into carrier color signal data by a digital color-1-encoder, and then D/A converted to obtain the carrier color signal. The crosstalk component of the converted analog signal or the obtained carrier color signal is shifted by 1/2 of the horizontal synchronization frequency with respect to the original signal.
- Can be removed using a comb filter, PS treatment,
The effects of PI treatment are not lost.

Detailed explanation of the invention According to the present invention, a sampling means using an A/D converter and a digital circuit of a simple configuration.
:S-PS11! Low-frequency conversion color signals that have become discontinuous due to l or PI processing can be made into continuous digital color difference signals without losing the crosstalk removal effect of PS or PI processing, making subsequent signal processing easier. Since analog frequency conversion is not used, color signal processing can be easily digitized, and circuit integration and cost reduction are possible.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of a color signal processing device according to an embodiment of the present invention, FIG. FIG. 4 is a circuit block diagram of a color signal processing device in another embodiment of the present invention. 5... A/D converter, 6... Sign inversion circuit, 7a. -13- 7b-=-latch circuit, 8a, 8b, 11.1
4.16.18... Flip-flop, 9... Frequency divider, 10... Shift register, 12... Up/down counter, 13.20... Data selector, 15.
・・Exclusive OR circuit, 17・・Inverter, 19・
...Logic product circuit agent Yoshihiro Morimoto-14- Fig. 2 - (R-Y) axis I# Fig. 3

Claims (1)

[Claims] 1. A low frequency converted color signal that has been subjected to phase shift or phase inversion processing has a frequency four times as high as the low frequency carrier frequency [
One output is a low frequency conversion burst based on the horizontal synchronization pulse and field discrimination signal from the clock, a sign-inverted pulse and a sign-inverted pulse synchronized in phase with each other at the same frequency. pulse generating means for creating a color difference signal separation pulse having twice the frequency of the sign inversion pulse; A signal processing device configured to obtain two color difference signal data from the low frequency converted color signal.2. Na-1
- The pulse generating means generates four-phase pulses having the same frequency as the low-frequency carrier frequency from a clock having a frequency four times the low-frequency carrier frequency, and converts these four-phase pulses into one.
2. The color signal processing device according to claim 1, further comprising a configuration in which 1q pulses with the same sign and inversion are sequentially switched every horizontal period. 3. The low frequency conversion color signal is subjected to phase inversion processing, and the pulse generating means generates a frequency four times as high as the low frequency carrier frequency. Create two pulses: a frequency pulse and a pulse that is the inversion of this pulse.
1. The color signal processing device according to claim 1, wherein the color signal processing device is configured to switch the sign-inverted pulse to 1q by switching to 1q.