JPH0423593A - Magnetic recording/reproducing device and signal processing circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a system configuration of a magnetic recording/reproducing device or a digital signal processing circuit, and in particular, to a system configuration of a magnetic recording/reproducing device and a cross section of a luminance/chromaticity separation circuit and a reproduced chromaticity signal. This invention relates to a system configuration for dual-use talk removal circuits.

[Conventional technology]

A magnetic recording/reproducing device that records a chromaticity signal by converting it to a low frequency requires a Y/C separation circuit that separates a composite video signal into a luminance signal and a chromaticity signal during recording. In an NTSC luminance signal, signal energy is often concentrated at a position that is an integral multiple of f, (9 is 1 horizontal scanning frequency). Utilizing this, the chromaticity signal is subjected to hue phase modulation at a carrier frequency (rsc) located in a frequency band between them. Therefore, the phase of the chromaticity signals indicating the same color is reversed every IH ( ], H is one horizontal scanning period).

In this way, the chromaticity signal is frequency interleaved and superimposed within the band of the luminance signal. Therefore, in a magnetic recording/reproducing device that records all bands of luminance signals, for example, IH
A so-called comb filter is used which separates a luminance signal and a chromaticity signal by adding or subtracting signals of two vertically adjacent lines using delay means. However, if the luminance signal and chromaticity signal are separated using only a comb filter, if there is no correlation between the chromaticity signals of two adjacent lines, so-called dot interference occurs in which part of the chromaticity signal turns into a luminance signal. do. Therefore, this dot interference can be prevented by detecting the vertical correlation of the chromaticity signals and appropriately switching between a comb filter and a band pass filter (hereinafter referred to as BPF) in accordance with the correlation. Here, we explained that the phase of chromaticity signals indicating the same color is reversed for each line.
On the other hand, when the signals of two adjacent lines are in phase, it is impossible to distinguish from the information of the two lines alone whether it is a luminance signal or whether it is due to hue inversion. Therefore, in order to accurately determine the vertical correlation of chromaticity signals, 2
H or more delay means are provided, and at least 3 vertically adjacent delay means are provided.
Vertical correlation is determined based on the phase information of the signal above the line.

On the other hand, the separated chromaticity signal is converted to a lower frequency and then recorded. However, at low frequencies, the effect of removing crosstalk from adjacent tracks by azimuth recording is small.

Therefore, so-called PS processing or PI processing is performed so that the crosstalk components from adjacent tracks mixed into the reproduced chromaticity signal have an opposite phase for each line considering the phase of the original chromaticity signal.
It is recorded after performing phase processing called processing. As a result, crosstalk components from adjacent tracks mixed into the reproduced chromaticity signal are present in the same phase for each line, that is, in a frequency band in which a luminance signal exists in a composite video signal. Therefore, this crosstalk component can be removed by using a comb filter.

However, if crosstalk is removed using only a comb filter, the vertical resolution of the chromaticity signal will deteriorate. Therefore, as with the Y/C separation circuit during recording, it is necessary to determine the vertical correlation by some method and control the on/off of the comb filter. As mentioned above, National Technical Report VO1, 34N (16Decl, 988P, 4
8-55 “S-V H5VTR high image quality technology”
Examples include the magnetic recording/reproducing device described in .

Also, have we explained about NTSC signals so far?
Similarly, in the case of the PAL signal, by utilizing the fact that the energy of the luminance signal is concentrated at an integral multiple of fi+, phase modulation of the hue is performed at a carrier frequency located in the frequency band between the chromaticity signal and the chromaticity signal. has been done.

However, in PAL chromaticity signals, signals indicating the same color are LH
The phase changes by a quarter period every time, that is, it is inverted every 2H. Therefore, in order to configure a comb filter, a 2H delay means is required, and
In order to perform vertical correlation detection, a delay of 1H is performed using a 4H delay means.
Phase information of every other three adjacent lines is required. An example of detecting vertical correlation using the above delay means configuration is a color signal crosstalk removal circuit described in Japanese Patent Laid-Open No. 1-162090.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into consideration the fact that the main parts of the adaptive Y/C separation circuit during recording and the adaptive chromaticity comb filter during playback can be shared, and there is a problem with increasing the scale of the system. Ta.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording and reproducing apparatus in which the main parts of the adaptive Y/C separation circuit and the adaptive chromaticity comb filter are used in common, and the system is streamlined.

Another object of the present invention is that when the adaptive Y/C separation circuit and the adaptive chromaticity comb filter are used together, LH (2
H) In addition to providing a reasonable luminance signal delay means for the above delays, if the shared system is configured by digital signal processing, a system that also shares peripheral circuits necessary for digitalization and analogization. Our goal is to provide the following.

[Means to solve the problem]

In order to achieve the above object, it was decided to use the vertical correlation determining means of the Y/C separation circuit during recording as the vertical correlation determining means of the chromaticity signal crosstalk removal circuit during reproduction.

Furthermore, it was decided to provide a dedicated delay circuit for the luminance signal in order to delay the chromaticity signal during reproduction due to vertical correlation determination.

In particular, when the Y/C separation/chromaticity signal cross-removal circuit itself is configured with digital signal processing to improve stability and vertical correlation detection accuracy, the delay means for the reproduced luminance signal also uses digital signals. Constructed by processing. At this time, as a means for analogizing this luminance signal, two digital-to-analog converters (hereinafter referred to as D/A) are used for the luminance signal and chromaticity signal during recording, but one is left over during playback, so by reusing this, We have streamlined the system as much as possible.

[Effect]

The Y/C separation circuit during recording is composed of a BPF, a chromaticity comb filter, a vertical correlation detection circuit, and a subtracter that subtracts the chromaticity signal from the composite video signal to obtain a luminance signal. here,
If the vertical correlation detection circuit determines that there is a correlation, the chromaticity signal is separated and extracted by the chromaticity comb filter. Also,
If it is determined that there is no correlation, the chromaticity signal is separated and extracted by the BPF. In this way, the chromaticity signal adaptively separated and extracted by the vertical correlation detection circuit is subtracted from the composite video signal to extract the luminance signal. On the other hand, when operating as a chromaticity signal crosstalk removal circuit during reproduction, chromaticity comb filter processing is performed when the vertical correlation detection circuit determines that there is a correlation. However, if it is determined that there is no correlation, the current signal is output as is, or a signal obtained by performing simple delay adjustment processing on the current signal is output. This ensures that the chromaticity signal has the same B during recording and playback.
Since the signal does not pass through the PF twice, there is no concern about deterioration of frequency characteristics in this circuit.

Further, especially when the Y/C separation/chromaticity signal crosstow removal circuit and the reproduced luminance signal delay circuit are configured by digital signal processing, all of their operations are strictly controlled by the clock.

Therefore, so-called comb shift, in which the comb frequency of the comb filter deviates, and delay time differences between luminance and chromaticity do not occur.

Furthermore, there is no need to worry about an increase in noise due to temperature rise.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

First, the configuration shown in FIG. 1 will be explained. 1 is an adaptive Y/C separation circuit during recording and a circuit that operates as an adaptive chromaticity crosstalk removal circuit during playback (hereinafter referred to as a Y/C separation/chromaticity crosstalk removal circuit); 2 is an IH delay line (hereinafter referred to as IT- 3 is a recording chromaticity signal processing circuit that typically performs low frequency conversion processing, 4 is a recording luminance signal processing circuit that typically uses FM modulation, 5 and 14 are adders, 6 is a recording amplifier, and 7 is a cylinder. 8 is a magnetic tape, 9 is a reproduction amplifier, 10 is a low-frequency leakage circuit (FLPF), 11 is a high-frequency leakage circuit, and 12 converts the chromaticity signal converted to the low frequency to the original A reproduced chromaticity signal processing circuit typically performs processing for restoring to a frequency band, 13 is a reproduced luminance signal processing circuit typically performs FM demodulation, and 15 to 19 are switches.

Next, the operation of this embodiment will be explained. When recording,
The composite video signal input to the composite video signal input Vin is input to the Y/C separation and chromaticity crosstalk removal circuit via the switch 15. Here, the signal is adaptively separated into a luminance signal and a chromaticity signal according to the vertical correlation. The separated luminance signals are input to the recording luminance signal processing circuit via switches 19 and 16. Further, this luminance signal is added to the chromaticity signal at the output 5out and the adder 14, and outputted to Vout for monitoring. The chromaticity signals separated in step 1 are input to the recording chromaticity signal processing circuit via switch 17. Also, like the luminance signal, it is added to the luminance signal at 5out and the adder 14 and V
A monitor output is output to out. The chromaticity signal and luminance signal processed in steps 3 and 4 are added together in an adder 5 to form a single signal, which is then amplified by a recording amplifier, passed through a switch 18, and is recorded onto a tape by a cylinder bed.

be done. When luminance/chromaticity separation input is used during recording, Y/C separation processing is not necessary, so recording luminance signal processing is performed via switches 16 and 17, respectively.

Input to recording chromaticity signal processing. After this, the processing up to recording on tape is as described above. Next, at the time of reproduction, the signal recorded on the tape is read out by the cylinder head, passed through the switch 18, and amplified by the reproduction amplifier. From this signal, a chromaticity signal which has been converted to a low frequency by an LPF is separated and inputted to a reproduced chromaticity signal processing circuit.

Further, the luminance signal that has been FM modulated by the HPF is separated and input to the reproduced luminance signal processing circuit. The chromaticity signal restored to the original frequency band at step 12 is input to the Y/C separation and chromaticity crosstalk removal circuit via switch 15.

Here, crosstalk components from adjacent tracks are removed from the chromaticity signal according to the vertical correlation. The chromaticity signal obtained in this manner passes through the switch 17 and is outputted 5 out in the same manner as during recording.

It is output to Vout. In addition, the luminance signal FM demodulated in step 13 is delayed and matched with the chromaticity signal by I HD L, and then passed through switches 19 and 16 to the 5o signal as during recording.
As described above, a magnetic recording/reproducing apparatus can be constructed in which the adaptive Y/C separation circuit during recording and the adaptive chromaticity crosstalk removal circuit during reproduction are combined. This has the effect of streamlining the system of the magnetic recording/reproducing device.

Next, we will explain specifically how the Y/C separation and chromaticity crosstalk removal circuit is dual-purposed, as shown in Figure 2.
This will be explained using the specific example shown in FIG.

First, the configuration of FIG. 2(a) will be explained. 20°2
0' is I HDL, 21.22.23 is coefficient unit, 24
is an adder, 25.29 is a subtracter, ' 26.27.2
7' is a BPF, 28°28', 28'' is a delay circuit (
DL), 30 is a detection circuit, 31.31', 3
2 is a switch.

Next, the operation of this specific example will be explained. When operating as a Y/C separation circuit, a composite video signal is input from VCin and delayed by IH and 2H by I HD L20, 20'. Here, the subtracter 25 subtracts the currently input signal and the signal input 2H ago. Therefore, the temporal center of gravity of the signal output from this subtractor is IHDL20
corresponds to the output signal of It also has a comb filter characteristic, and its null point is f,. ±−f, , (n is an integer, the same applies hereafter).

The energy of the signal is concentrated around fSC±f11. Further, when the vertical correlation of the chromaticity signal is strong, the energy of the signal is concentrated around fsc nf. In other words, it can be said that the above-mentioned comb filter characteristic has a large output when the vertical correlation is weak. FIG. 3(b) shows this relationship. Therefore, after the output signal of the subtracter 25 is limited to the chromaticity signal band by BPFI, the vertical non-correlation detection is performed by detecting the signal at 30. On the other hand, the current input signal and IHDL20 (7) output and 1HDL20
By adding the three signals of the outputs of "■ and 24" in the adder 24, a chromaticity comb filter with null points at fSC±fI+ is constructed.The output of this chromaticity comb filter has a chromaticity of After limiting the signal band to the signal band, the signal is input to the switch 32 via the switch 31'.The output signal of the LHDI 20, which corresponds to the output signal of this chromaticity comb filter and the temporal center of gravity, is
After being band-limited by the chromaticity signal by the BPF 2 of 7', the signal is inputted to the switch 32 via the switch 31. This switch 32 operates to select the output of the switch 31' when there is a correlation in the previous vertical non-correlation detection signal, and to select the output of the switch 31 when there is no correlation. In this way, the chromaticity signals separated according to the vertical correlation are extracted from the output of the switch 32. Furthermore, the signal of 1HDL20 is
After delaying with a delay circuit 28'' having the same amount of delay as 2, by subtracting the output signal of the switch 32 with a subtracter 29,
The luminance signal is separated. Next, a case will be described in which the circuit operates as a chromaticity crosstalk removal circuit. The determination method of the vertical correlation detection, the characteristics of the chromaticity comb filter, and the control of the switch 32 are the same as in the case of Y/C separation. The different parts are the output of the chromaticity comb filter and 1
The output of the HDL 20 is not band-limited by the BPF 2 of 27.27', but only the delay is adjusted by the DL of 28.28'. This is because the input chromaticity signal has already been band-limited, and if the band-limiting of BPF2 is performed again, the horizontal resolution of the chromaticity signal will deteriorate.
I try not to do this.

I have explained the operation above, but these are all NTS
This holds true for the C signal. I won't go into details, but in the case of PAL signals, IHDL20 and I
Similar processing becomes possible by setting the delay time of the HDL 20' to a length of 2H. However, in this case, IHDL2, which is the delay means for the reproduction luminance signal shown in FIG. 1, must also be changed to 2H.

As can be seen in this specific example, most of the adaptive Y/C separation circuits and adaptive chromaticity crosstalk removal circuits can be used in common.

Next, a second specific example of the Y/C separation/chromaticity crosstalk circuit will be described with reference to FIG. First, the configuration of FIG. 3(a) will be explained. The parts that overlap with FIG. 2(a) are omitted. 35.35' is a phase inversion circuit.

36, 36', 39 are circuits that output the larger of the two input signals (hereinafter referred to as MAX), 37.38.
38' is a circuit that outputs the smaller of the two input signals (hereinafter referred to as MIN), 40 is an adder, 33.33',
33" BPF, 34 is DL, 56.56',
56'', 56''' are switches.

Next, the operation will be explained using FIG. 3(b). When operating as a Y/C separation circuit, the composite video signal input to VCin is IHDL20 and 1HDL20'
delay by IH and 2H, respectively. The respective signals are band limited to the chromaticity signal band by B P F33.33'33''.

The outputs of BPFs 33 and 33'' are input to MAX and MIN via switches 56 and 56''. Also, BPF33
The output of ' is inputted to MAX and MIN after passing through a switch 56' and having its phase inverted by a switch 35.

Here, if the output of the switch 33 is the output of the a9 reverse rotation 35, and the output of the switch 33'' is C, then a.

The magnitude relationship between b and c is basically classified into the six patterns shown in (b). For these six patterns, M I N
If the outputs of 37 and MAX39 are x and y, respectively, then x
, y are as shown in (b). here,
If we consider that the phase of b is inverted, we get
If there is even a slight vertical correlation in the high frequency components of the luminance signal (b)
It can be seen that it belongs to ■～■. Also, (b) ■～■
Either x or y of is always b. Also, those who are not b are a
Alternatively, it can be seen that a value closer to b is selected among C. That is, in the case of (1) to (2), the adder 50 performs chromaticity comb filter processing between two lines between b and a signal with a stronger correlation.

Further, since there is no correlation between ■ and ■ in the high frequency band of the luminance signal, b is selected for both x and y, and as a result, the output of the adder 50 also becomes b. In other words, chromaticity signal extraction was performed by band separation using the BPF 33.

It becomes. As described above, the chromaticity signal extracted according to the vertical correlation is outputted from the adder 40.

The output of the adder 40 is converted to 1 by a coefficient unit 41 for gain adjustment.
After being multiplied by 72, the signal is returned to its original phase by an inverting circuit 35' and output. In addition, the brightness signal is IHDL2
This is obtained by delaying the output of 0 by the DL 34 by the same amount as the BPF 33' and then adding it to the coefficient unit 41. When operating this circuit as a reproduction chromaticity gloss removal circuit, switch 56.56', 56756'' is set to BP.
This can be achieved by selecting from the side that does not pass through F or DL. This is a measure to prevent the reproduction chromaticity signal band from being impaired, similar to what was explained in FIG. 2. In addition, this specific example also describes all NTSC signals, but like the example in FIG. 2, IHDL
By setting the length of 20 and IHDL20' to 2H, P
A similar operation can be realized for AL signals as well.

The first embodiment has been described above, including a specific example of a circuit that serves as both a Y/C separation circuit and a crosstalk removal circuit.According to this embodiment, "20 adaptive Y/C separation during recording" By combining the circuit and the adaptive chromaticity crosstalk removal circuit during playback, it is possible to keep the system configuration small and provide an image without displacement between the luminance signal and the chromaticity signal.

Next, a second embodiment of the present invention will be described using FIG. 4. This embodiment has a different structure within the dotted line frame of FIG. 1, which is a block diagram showing the first embodiment, and only that part is illustrated. Its structure is (a
), a simple IHDL was used as a means for delaying a luminance signal during reproduction, but the luminance feedback noise retainer (hereinafter referred to as YNR) of 43 was used. Here, a specific configuration example of YNR is shown in (b). Its operation is
A difference is taken between the input luminance signal and the output of the 1HDL 49, and from this difference, a signal with a minute amplitude is extracted by a limiter 47. This is considered to be a noise component and is appropriately attenuated by a coefficient multiplier 46, and then converted into an input signal. The noise component is suppressed by feedback. Currently, CCD delay lines are the most commonly used means for delaying luminance signals.

Although CCDs are relatively inexpensive and easy to use, they also have drawbacks such as poor signal-to-noise ratio.

Therefore, as a means of delaying the reproduced luminance signal, a simple IHD
By using YNR instead of L, S/
N can be improved. Therefore, according to this embodiment, the luminance signal can be simultaneously delayed without deteriorating the S/N ratio of the luminance signal.

In addition, as shown in Figures 2(a) and 3(a), Y/
IHDL is also used in the C separation and chromaticity crosstalk removal circuit. Therefore, the S/N of the luminance signal may deteriorate here as well. In order to fundamentally improve this point, as shown in Figure 4(C), a Y/C separation and chromaticity crosstalk removal circuit is constructed using digital signal processing.
It is conceivable to configure IHDL with digital memory.

Next, a third embodiment of the present invention will be described using FIG. 5. If the delay processing circuit is configured by digital signal processing as shown in FIG. 4(C), there is no need to worry about S/N deterioration. Further, by digital signal processing for the delay processing of the reproduced luminance signal, a circuit configuration that does not require the use of a YNR circuit can be achieved. At this time, the fifth
By employing the configuration shown in FIG. 2A, the increase in peripheral circuits accompanying digital signal processing can be reduced to some extent. In other words, the circuit that controls the memory means for delaying the luminance signal is configured on the same IC as the Y/C separation and chromaticity crosstalk removal circuit, and only the control signal is transferred to the IC.
It is output from within (here, as an example, clock CK and reset Re5et). Furthermore, since the memory output and the IC output are used in mutually exclusive modes, by controlling one output to high impedance, the D/A
Converters can be shared. Furthermore, by making it possible to delay the chromaticity signal including the delay amount of the chromaticity signal by digital signal processing of other chromaticity signals as shown in FIG. 5(b),
Another advantage is that it is possible to easily follow the upgrading of chromaticity signal processing. Examples of various chromaticity signal processing include TV Science and Technology Report Vol. 1.13 Nα38PP, 11-16.
(Aug, 1989) Chroma noise reducer described in ``Development of roman noise reducer for VTR'' and TV magazine Vol. 1.44 N (12PP, 183-18
6 (Feb, 1990) "Digital Color Enhancer for rS-VH3 VTR", etc.

Further, when a D/A converter is also built into the same IC as in the example shown in FIG. 6, a configuration similar to that shown in FIG. 5 can be achieved by providing a digital input.

〔Effect of the invention〕

According to the present invention, it is possible to combine the adaptive Y/C separation circuit during recording and the adaptive chromaticity comb filter during playback, so it is possible to configure a magnetic recording and playback device with a streamlined system, and at the same time This has the effect of reproducing images without displacement between the chromaticity signal and the chromaticity signal.

Furthermore, according to the present invention, if the adaptive Y/C separation circuit and adaptive chromaticity comb filter combination circuit are constructed using digital signal processing, the /A converter required for analogization can be used for recording and playback. In addition to being effective in reducing the size of the system, it is also possible to provide a system with a degree of freedom in which the delay time of the luminance signal can be easily adjusted for the addition of other chromaticity signal processing.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention;
The figure is a block diagram showing a configuration example of an adaptive Y/C separation circuit and adaptive chromaticity crosstalk removal circuit, and FIG.
A block diagram showing a second configuration example of a C separation circuit/adaptive chromaticity crosstalk removal circuit, FIG. 4 is a block diagram 1 showing a second embodiment of the present invention, and FIG. 5 is a block diagram showing a third embodiment. FIG. 6 is a block diagram showing another configuration example of FIG. 5(a). 1... Adaptive Y/C separation circuit/adaptive chromaticity crosstalk removal circuit 2... IH delay line 3... Recording chromaticity signal processing circuit 4... Recording luminance signal processing circuit 12... Reproduction chromaticity signal processing circuit 13...Reproduction luminance signal processing circuit 30...Correlation detection circuit 31...Luminance line noise reducer 50...Analog-digital converter 51...Digital-analog converter 52... ...Memory control circuit 53...Memory 54...Various chromaticity signal processing G ■ ■ ■

Claims (1)

[Scope of Claims] 1. In a video signal magnetic recording and reproducing device that performs low-frequency conversion processing on chromaticity signals, the correlation between chromaticity signal components of at least three or more vertically adjacent lines of a composite video signal during recording is determined. vertical chromaticity correlation determining means; inter-line chromaticity comb filter means for extracting chromaticity signal components when the vertical chromaticity correlation determining means determines that there is a correlation; and the vertical chromaticity correlation determining means a bandpass filtering means for extracting a chromaticity signal when it is determined that there is no correlation; and a chromaticity signal extracted by the bandpass filtering means and the chromaticity comb filtering means is subtracted from the decoded video signal to determine the luminance. and a subtraction means for extracting a signal, and the vertical chromaticity correlation determination circuit appropriately switches on/off of the chromaticity comb filter means to convert the chromaticity signal during playback to the composite video signal during recording. A magnetic recording/reproducing device characterized by extracting a magnetic signal. 2. A/D conversion means for digitizing the composite video signal; means for performing the vertical chromaticity correlation determination on the digital signal; means for performing the chromaticity comb filter processing on the digital signal; means for performing the bandpass filtering on the digital signal, means for subtracting the chromaticity signal from the composite signal to obtain a luminance signal, and extraction by the digital chromaticity comb filter means and the digital bandpass filtering means. The first D/
A converting means, and a second D converting the luminance signal into analog.
/A converting means, digitizing the chromaticity signal during reproduction by the A/D converting means, and appropriately switching on/off of the digital chromaticity comb filter means by the digital vertical chromaticity correlation determining means. second A/D converting means for converting the extracted chromaticity signal into analog by the first D/A converting means and digitizing the luminance signal during reproduction;
comprising memory means for delaying the digitized luminance signal and means for controlling the delay time of the memory means;
At least the digital vertical chromaticity correlation determination means, the digital chromaticity comb filter means, and the digital bandpass filter means are integrated on the same IC, and the reproduced luminance signal output from the memory means is transmitted to the second 2. The magnetic recording/reproducing apparatus according to claim 1, wherein the data is converted into analog data by a D/A conversion means. 3. The reproduced chromaticity signal is converted to S/S by digital signal processing.
chromaticity signal processing means, which is a means for enhancing the contour of the reproduced chromaticity signal; or a means for simultaneously performing the digital chromaticity S/N improvement means and the contour enhancement means; 3. The memory control means is provided before or after the first D/A converter, and the memory control means is capable of performing delay control including a delay time caused by the chromaticity signal processing. magnetic recording and reproducing device. 4. In the digital signal processing means, means for outputting a memory control signal that makes it possible to realize a delay of the same amount as the signal delay time caused by the digital signal processing is provided on the same IC chip as the digital signal processing means. A digital signal processing circuit characterized in that it is configured as follows.