JPS6194488A - Chrominance components processing device - Google Patents

Abstract

PURPOSE:To make a circuit simple, to improve performance and to decrease the number of parts by sampling a burst part of two demodulated color difference signal digital data, and generating control signals of ACC action, APC action, and color killer action. CONSTITUTION:After passing an ACC amplifier 2, a low area converting chrominance components are fed to an A/D converter 33, a clock for converting is set to the frequency of four times of a low range converting carrier wave, the clock phase is controlled so that converting data may repeat digital data of B-Y, R-Y, -(B-Y) and -(R-Y), a decoder 34 inverts and separates a code, two color difference signal data are obtained, then the data is added by comb- shaped filters 35 and 36 to the data before one period, data (R-Y) and (B-Y) are obtained, an encoder 37 inverts a code, the output is repeatedly executed by a four times clock of a reference carrier frequency, and after D/A conversion 38 is applied, a carrier chrominance component is obtained through BPF39. The burst part of the data (R-Y) and (B-Y) is sampled by a gate 40, and the signal for controlling respective actions of ACC, APC and a killer is generated at the circuit 53.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a color signal for recording and reproducing color signals in a magnetic recording and reproducing apparatus (VTR), which performs color correction of the modulation frequency, signal level correction, and black and white signal discrimination. It relates to a processing device.

Configuration of Conventional Example and Its Problems FIG. 1 is a block diagram showing the configuration of a conventional color signal processing device. A conventional example will be described below with reference to the drawings.

During recording, a carrier color signal with a carrier frequency of /5c (3.68 MH2 in the NTSC system) is input from terminal 1, and the carrier color signal is
After the level is adjusted to an appropriate level by a C amplifier (CC) 2, the signal is supplied to one input of a frequency converter 3. The other input of the frequency converter 3 has a low frequency conversion frequency fc.
(In the VH8 system, the horizontal frequency f is 40 times I, which is 629K.
A carrier with a frequency fsa '' fc which is the sum of the carrier frequency fsc of the carrier color signal inputted from the terminal 1 is inputted to the carrier color signal H2) and the carrier color signal whose level has been adjusted and the frequency. 3, and the resulting low-pass conversion color signal at the carrier frequency is extracted by a low-pass filter (LPF) 4 and sent to a killer switch (KIL) via a switch 6 for recording/reproducing output.
LER3W)7. The control terminal of the killer switch 7 (this terminal is supplied with the result of determining the presence or absence of a color signal, and is used to switch whether or not to supply the low-frequency conversion color signal from the switch 6 to the output terminal 8. I am doing it.

During playback, a low frequency converted color signal with a carrier frequency of 10 is input from a terminal 1, the level is adjusted by an A'CG amplifier 2, and the signal is supplied to one of the frequency converters 3.

The other terminal of the frequency converter 3 is connected to the terminal 1.
The frequency fs is the sum of the carrier frequency f of the low-pass converted color signal input from the input carrier and the reference carrier frequency fsc for the reproduced carrier color signal.
c ten fc carriers are supplied. The level-adjusted low-pass conversion color signal and the carrier of frequency fsc+fc are multiplied by a frequency converter 3, and the resulting carrier color signal of base carrier frequency fsc is passed through a bandpass filter (BPF).
) is extracted and output to terminal 8 via switch 6 and killer switch. The killer signal is controlled as a result of determining the presence or absence of a recording time-like color signal. In the above-mentioned recording and reproducing system, the ACC amplifier 2 performs a CC operation to adjust the carrier color signal input from terminal 1 or the low-frequency conversion color signal to an appropriate level, and adjusts the carrier color signal input from terminal 1 to an appropriate level. The carrier of frequency jsc+fc supplied to the frequency converter 3I is given a similar phase jitter to match the phase jitter of the carrier wave of the signal or low-pass converted color signal. The PC operates to set the phase to a predetermined value, determines whether a carrier color signal or a low-frequency conversion color signal is input from terminal 1, and does not output a signal to the terminal if there is no color signal. Color killer motion has traditionally been performed in the following manner.

The switch 9 captures the carrier color signal after passing through the CC amplifier 2 during recording, and captures the frequency-converted reproduced carrier color signal after passing through the bandpass filter 6 during playback. The burst part is extracted by zo.

Regarding the ice operation, during recording and reproduction, the peak level of the extracted burst is detected by the ice detector (ACCDET) 11, and the peak level is detected by the low pass filter (LPF) 12.
The signal is converted to a level and supplied to the ACC amplifier 2 as a gain control signal. For example, the ACC amplifier 2 operates in a direction in which the gain decreases when the DC voltage of the gain control signal is high, that is, when the burst level is large, and conversely, when the DCi voltage of the gain control signal is low, the gain increases. The feedback loop described above operates so that the level C of the color signal becomes constant. Regarding the APC operation, during recording, the signal generator (v*o) 13 works as a voltage controlled oscillator and oscillates at the color subcarrier frequency fsc, and this oscillation output and the burst extracted by the burst gate 10 are sent to the phase comparator (PCl). ) 1a, and the result is fed back to the frequency control input of the signal generator 13 via a low-pass filter (LPF) 16 and a switch 16, whereby the signal generator 13 performs synchronous detection using a phase comparator 14, and outputs the result to the low-pass filter. It oscillates at a frequency where the result of passing through 15 is O. The oscillation output from the signal generator 13 becomes a color subcarrier synchronized with the extracted burst with a phase difference of 90°, and is supplied to one input of the frequency converter 17. A low-frequency converted carrier wave is supplied to the other side of the frequency converter 17, which is first supplied to the phase comparator (PO2) 1 during recording.
8. Low pass filter (LPF: z9, switch 20,
Voltage controlled oscillator (VCO) 21, frequency divider ('/n) 22
A phase locked loop (hereinafter PLL) consisting of
) creates a signal with a frequency nfB, which is the frequency of the horizontal synchronizing signal input from the terminal 23 multiplied by n (n is a positive integer), and divides the frequency in the signal creation circuit (PS/PI) 24. Based on the recording track discrimination signal PG and the horizontal synchronization signal input from the terminal 25, the phase is softened by 900 in the opposite direction in each trunk every horizontal period (hereinafter referred to as PS processing), and every other track is It is created by performing processing to invert the phase every horizontal period (hereinafter referred to as PI processing), and the frequency f0 is 409 when recording an NTSC television signal using the VH8 system, and 90 times per horizontal period. It will be shifted while moving. During recording, the frequency converter 17 multiplies the color subcarrier of frequency fsc by the low frequency converted carrier of frequency fc, and the frequency converter 17 multiplies the color subcarrier of frequency fsc by the low frequency converted carrier of frequency fc.
PF) 26 extracts a signal of HJti number fsc + fc and supplies it to the frequency converter 3. From this, the low-frequency conversion carrier wave of the low-frequency conversion color signal that is finally output from the terminal 8,
It operates so that it is synchronized with the low frequency conversion color signal created by the signal creation circuit 24. Furthermore, during reproduction, the signal generator 13 is frequency controlled by a constant voltage from a constant voltage circuit (REF) 27 via a switch 16, so it becomes a reference oscillator that generates a color subcarrier of the reference frequency/sc, The phase comparator 14 is a low-pass filter 16 and a switch 2
0 to a voltage-controlled oscillator 21, the burst of frequency-converted reproduced carrier color signal finally output from terminal 8 is supplied to the voltage-controlled oscillator 21 via the reference signal generator 13. operates in synchronization with the color subcarrier of

Regarding the killer operation, during recording and reproduction, the burst extracted by the burst gate 1o is rotated at 90° with respect to the color subcarrier from the signal generation circuit 13 by the APC operation described in 1iiJ.
Since it has a phase difference of
KrLLERDICT) 29, and the extracted burst is passed through a synchronous I wave L and a low pass filter (LPF).
The comparator (, GOM
P) 29 determines the presence or absence of a color signal and supplies a switch control signal to the killer light cap.

In the conventional color signal processing device as described above, ACC,
In order to perform the operation of the PC and color killer, the peak level detection of the burst is performed, and the CC detector 11 detects the peak level of the burst.
, a phase comparator 14 that synchronously detects the burst and the color subcarrier from the signal generator 13, and a killer detector that synchronously detects the burst and the color subcarrier from the signal generator 13 shifted by 90 degrees. The three detection circuits of the detector 29 are required, and each circuit is complex and requires many peripheral circuits to obtain predetermined characteristics, and the performance of each operation is determined by the characteristics of the detection circuit and the subsequent analog low-pass filter. Therefore, it is difficult to set constants, and furthermore, the number of external parts is small.
, a human PC, makes it possible to simplify the circuit, improve performance, and reduce the number of parts by standardizing a part of the circuit that performs burst detection, especially for performing color killer operation, and further digitizing it - Color An object of the present invention is to provide a signal processing device.

Structure of the Invention The color signal processing device of the present invention includes means for demodulating a low-pass converted color signal into two color difference signal digital data, extracting a burst i portion of the two color difference signal digital data, and extracting the burst i portion of the two color difference signal digital data. After arithmetic processing of the two color difference signal digital data for i minutes, a control signal for adjusting the color difference signal level, a control signal for controlling the frequency and phase of the color signal, and a color signal are generated through a D/A converter, an analog filter, and a comparator. control signal generation means for generating a control signal for determining whether or not to output a color signal;
Operations: Performs various operations necessary for recording and reproducing carrier color signals, such as one-person PC operation and color killer operation.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram of a color signal processing device according to an embodiment of the present invention, and its operation will be explained below.

During recording, a carrier color signal with a carrier frequency fsc is supplied from terminal 1, its level is adjusted by an ACC amplifier (AGO) 2, and a low signal is sent to terminal 8 via a frequency converter 3, a low-pass filter 4, a switch 6, and a killer switch. The gamut-converted color signal is supplied as usual.

During playback, the low frequency converted color signal after passing through the ACC amplifier 2 is sampled by an A/D converter (A/D) 33 via a switch 32 using an integer multiple clock synchronized with the carrier wave of the low frequency converted color signal. gam/D conversion, and then a decoder (
DKCODE) 34, two color difference signal digital data I'l-Y,
B-Yl is digitally demodulated. In one embodiment of the present invention, the clock of the A/D converter 33 is operated at a frequency 41o that is four times as high as the low-frequency conversion carrier wave, and the M/D converted data is a color difference signal B-Y, R- Y, -(B-Y).

The phase of the clock is controlled so that -(RY) digital data is repeated, and the digital data is subjected to sign inversion and separation processing by a decoder 34 to obtain two color difference signal digital data. The two color difference signal digital data are processed by a digital comb filter (COMB).
) 36. At 36, it is added to the data of one horizontal period @ (two horizontal periods ago in the case of a PAL color video signal),
Two color difference signal digital data (R-Y)' from which harmonics due to crosstalk and sampling have been removed (
B-Y)' is obtained. The obtained two color difference signal digital data are sign-inverted by an encoder (KNCODE) 37 and set at a frequency 4 which is four times the reference carrier frequency fsc.
(RY)', (B-Y)' at 1S O's clock.

-(RY)' and -(B-Y)' are repeatedly output in the order of The components are removed to obtain a carrier color signal having a carrier frequency of /sc. The obtained carrier color signal is supplied to the terminal 8 via the switch 6 and the killer switch (KILLER5W) 7 as in the conventional manner.

During recording, the burst information necessary for Mu CC operation, Mu PC operation, and Color Killer operation is sent to the A/D converter 33 by a switch 32 after passing through the low-pass filter 4.
and the same two color difference signal digital data (
RY)', (B-Y)', and the color difference signal digital data (RY)', both during recording and reproduction.
, (BY)' is obtained by extracting the digital data of the burst portion with a burst gate (BG) 40.

Regarding ACC operation, if demodulation is performed accurately,
In the case of recording a color video signal using the NTSC system, the color difference signal data in the burst part has a certain negative magnitude as (B-Y)' data, and the absolute value of the (B-Y)' data is the same as that of the burst. This is equivalent to the peak level detection result and becomes burst level data. In addition, when demodulation is not performed accurately or when the color video signal of the PAL system (B
-Y)' has a constant negative magnitude and (RY)' has a certain magnitude.The burst level data as described above is obtained as digital data by the muca detector (ACCDET) 41. After being converted into an analog value by a D/A converter (D/A) 42, it is fed back to the human CG amplifier 2 via a low pass filter (LPF) 43, thereby controlling the level of the color signal to be constant.

The ACC detector 41 has a reference level for level control as digital data inside the above-mentioned song number,
The burst level digital data obtained above is compared with the reference level digital data, and digital data corresponding to the difference is supplied to the D/A converter 42. For example, the D/A converter 42 is configured as a current output type. The signal may be integrated by the low-pass filter 43 and used as a control signal for the ACC amplifier. Also A
Considering the response speed and stability of CC operation, the D/A converter 4
The digital data sent to 3 may be processed to have non-linearity. Furthermore, by averaging the color difference signal data in the burst section or the average of the burst level data in the ACiC detector 41, malfunctions due to noise contained in the low frequency converted color signal are also reduced.

Regarding human PC operation, whether the two color difference signal digital data (R-Y)' and (B-Y)' extracted by Burst Game 1-40 are accurately demodulated during recording and playback. By determining this, a phase error detection circuit (PCl) 44 supplies a value corresponding to the phase error as digital data to a D/A converter (D/A) 45,
The phase error is converted to an analog value and passed through a low-pass filter (
(LPF) 46 to obtain a control voltage for frequency one-phase control of carrier waves during recording and reproduction. For example, when recording and reproducing an NTSC color video signal, the D/A converter 45 uses the human CC digital data as a phase error.
and data (R, -Y)'.

Digitally calculate the above θ from (B-Y)' and tan θ=(R-Y)'/(B-Y')' (if calculated, 0 is nothing but a phase error).

Also, in the case of PAL color video signals (R-
Y)' Since the data is inverted every horizontal period, if we add the data (RY)' and (B-Y)' with the data one horizontal period ago, we get (B-Y)' (RY) ' component is canceled and treated in the same way as MTSCj method data.

In addition, as in the case of λCC operation, the phase error detection circuit 44
In consideration of the response speed and stability of the APC operation, processing may be performed to impart nonlinearity to the data sent to the D/A converter 45, or the average of the color difference signal data or the average of the phase error in the burst period may be calculated. This function can reduce malfunctions caused by noise. The method of performing APC operation using the side voltage of frequency 1 phase control described above requires a signal generator (VXO) 48 that oscillates at a frequency of 4 fsC to operate the encoder 37 during playback, so this is controlled by voltage control during recording. It is operated as an oscillator.

The control voltage after passing through the low-pass filter 46 is supplied to a signal generator 48 via a switch 47, and the resulting signal with a frequency of 4fSG is passed through a frequency divider (1/4) 49 to obtain a signal with a frequency of fsc. , multiplied by the frequency converter 17 with the low frequency converted color signal, and passed through the bandpass filter 2S.
extracts a signal with frequency fsa+fa and supplies it to the frequency converter 3, and the low-frequency converted carrier wave of the low-frequency converted color signal finally taken out from the terminal 8 is synchronized with the low-frequency converted carrier wave supplied to the frequency converter 17. controlled like this. As in the conventional example, the low-frequency conversion carrier wave supplied to the frequency converter 17 is composed of a phase comparator (PO2) 18, an o-pass filter (LPF) 19, a switch 20, and a voltage regulator a1 output ii (
The frequency 9 of the horizontal synchronizing signal input from the terminal 23 is multiplied by n by a PLL composed of a frequency divider (1//n) 21 and a frequency divider (1//n) 22, and becomes 4fc-, which is four times the low frequency conversion frequency.
n/, I are created, and the signal creation circuit (PS/
PI) 24 and the horizontal synchronization signal and terminal 25
PS or P according to the track discrimination signal PG input from
It is created by performing I processing. Further, the signal with the frequency 'fa is supplied to the human/D converter 33 as a clock, and the low frequency conversion carrier wave with the frequency fc is supplied to the decoder 34,
It is also used as a signal for demodulating the low frequency converted color signal into two color difference signal dental data both during recording and reproduction. Reproduction special program In order to convert the demodulated two color difference signal digital data (R-Y)I, (B'-Y)' into a carrier color signal with a reference carrier frequency fsc, the signal generator 48 performs frequency 1 phase control. Since the constant voltage from the constant voltage circuit (REF) 50 becomes the control input via the switch 45, a signal with a reference frequency of 4fSG is generated and supplied to the encoder 37.

APO operation is controlled by passing through the low-pass filter 46.
, the subsequent control voltage is passed through the switch 20 to the voltage controlled oscillator 2.
1 and the frequency 4/c supplied to the human/D converter 33.
The signal generating circuit 24 controls the frequency 1 phase of the signal with the frequency f0 supplied to the clock and decoder 34, and finally converts the burst of low frequency converted color signal after passing through the CC amplifier 2 into the signal generating circuit 24.
The low-frequency conversion carrier created by
', CB-Y)' is obtained.

For killer operation, it is sufficient to obtain a signal equivalent to the output of synchronous detection, which is nothing but a value with the sign of the B-Y data in the burst part inverted. For example, a killer detector (
KILLERDICT) sl burst part (B-Y
)' Invert the sign of the data, create a boundary for determining whether or not to perform the internally set color killer operation, perform discrimination and counting every horizontal period, and supply the counting results to the comparator (GOMP) 52; Based on the counting results, the comparator 52 activates the color killer when the value is lower than the boundary for 5 consecutive horizontal periods, and releases the color killer when the value is higher than the boundary for 6 consecutive horizontal periods. By controlling switch 7, all operations can be performed digitally, and (B-Y)' data is directly D/A converted, passed through a low-pass filter as in the conventional example, and then converted to color killer using an analog comparator. It is also possible to decide whether to perform an action or not. As explained above, in the present invention, the ACC detector 4 receives data for performing the person CC operation, single person PC operation, and color killer operation from two color difference signal digital data, and performs the main detection operation.
1. The basic parts of the phase error detection circuit 44 and killer detector 61 are digitized, and the common operations of each circuit, such as the operation of averaging the color difference signal data of the burst portion, are performed in one circuit. This makes it possible to share the circuit and configure it as one digital circuit 53. In addition, the operation that was performed by the three detection circuits in the conventional example is already partly performed by demodulating the two color difference signal digital data of the burst part using the A/D converter 33 and the decoder 34. It is becoming common and digital.

One embodiment of the present invention has been described above, and the demodulation circuit corresponding to the A/D converter 33 and decoder 34 converts the low frequency converted color signal into two demodulation axes whose frequency 1 phase is synchronized with the low frequency converted color signal. Other digital circuits may be used as long as they convert color difference signals into digital data. Further, as a frequency conversion method during reproduction, it is also possible to perform frequency conversion using the conventional frequency converter 3 and provide a digital demodulation circuit for supplying two color difference signal digital data to the burst gate (BG).

Effects of the Invention As is clear from the above description, by demodulating the low frequency conversion color signal into two color difference signal digital data and then arithmetic processing the digital data of the burst portion of the digital data, the MuCC operation and the Apc operation can be performed. Since the control signals for each operation of the color killer operation are created, the only three detection circuits that were conventionally required are all digitized, and the common operation parts are shared, which has the effect of simplifying the circuit. Furthermore, by digitizing and performing arithmetic processing, control signals can be created freely, increasing the degree of freedom in circuit design, and improving the detection characteristics of each operation.

In addition to improving the response characteristics and creating characteristics that match the circuit devices to be combined and the signals to be processed, it also has the effect of achieving higher integration and lower power consumption by using MO5IC.

-Furthermore, during recording, the low-range converted color signal that has been low-range converted for recording is digitally demodulated, and during playback, the low-range converted color signal reproduced from the magnetic tape is digitally demodulated;
During playback, each of the above operations is performed from the data of the burst portion of the digitally demodulated low frequency conversion color signal, so as with the conventional example, the circuits that perform each of the above operations can be used in common for recording and playback, simplifying the circuit. It has the effect of

Furthermore, as a frequency conversion method for converting the low frequency converted color signal to a predetermined carrier frequency during reproduction, after demodulating the low frequency converted color signal into two color difference signal digital data, the two color difference signal digital data are converted to a predetermined carrier frequency. If the method of converting into a carrier color signal is used, there is no need to separately provide a circuit for demodulating the low-frequency converted color signal into two color difference signal digital data for performing each of the above operations, and the circuit can be simplified.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a conventional color signal processing device, and FIG. 2 is a block diagram of an embodiment of the color signal processing device of the present invention. 1.8, 23.25--Terminal, 2- AC amplifier, 3, 17- Frequency converter, 4.19.43゜46
・Low pass filter, 6.20.32.47・ Switch, 7... Killer switch, 18 ・Phase comparator, 2
1... Voltage controlled oscillator, 22.49... Frequency divider, 24...- Signal creation circuit, 26, 39... Band pass filter, 33 ・Mu/D converter, 34 Decoder, 35 , 36...Digital comb filter, 37...Encoder, 3B, 42. 46. D/mu converter, 40-purst gate, 41.
... Mu CO detector, 44 ・ Phase error detection circuit,
48...signal generator, 60...constant voltage circuit, 61
... ・Killer detector, 62 ・Comparator,
63- ・Digital circuit.

Claims (3)

[Claims] (1) demodulating means for digitally demodulating a low-pass converted color signal into two color difference signal digital data; extracting a burst portion of the two color difference signal digital data; and extracting the two color difference signal digital data of the extracted burst portion. After arithmetic processing, it passes through a D/A converter, an analog filter, and a comparator to determine the presence or absence of a control signal for adjusting the color signal level, a control signal for controlling the frequency and phase of the color signal, and a color signal, and outputs the color signal. Color signal processing characterized in that the color signal processing comprises a control signal generating means for generating a control signal for controlling whether or not the image is displayed, and an ACC operation, an APC operation, and a color killer operation are performed by the control signal obtained by the control signal generating means. Device. (2) During recording, the demodulating means demodulates the recorded low-frequency converted color signal into two color difference signal digital data for recording, and during playback, demodulates the reproduced low-frequency converted color signal reproduced from the magnetic tape into two color difference signal digital data. The color signal processing device according to claim 1, wherein the color signal processing device demodulates the color difference signal into digital data. (3) As a frequency conversion method for converting the low frequency converted color signal to a predetermined carrier frequency during reproduction, after demodulating the low frequency converted color signal into two color difference signal digital data, the two color difference signal digital data are converted to a predetermined carrier frequency. In order to perform the ACC operation, APC operation, and color killer operation, the demodulation means demodulates the low-pass converted color signal used as the frequency conversion method into two color difference signal digital del data using a method of converting it into a carrier color signal. 2. The color signal processing device according to claim 1, wherein the color signal processing device also serves as demodulation means.