JPH01140888A - Video tape recorder - Google Patents

Abstract

PURPOSE:To deal with the color video signal of a wide band, and at the same time, to prevent the deterioration of the vertical resolution of a reproduced color picture at the time of high density recording by providing a recording system with two stages of subtraction type comb line filters, which are cascade- connected. CONSTITUTION:The low band component of a carrier chrominance signal, taken out from the comb line filter 21 and a band-pass filter 22, is supplied to a frequency conversion circuit 24 through an ACC circuit 23, and after being frequency converted, it is recorded in a magnetic tape T by rotary magnetic heads HA, HB through an addition circuit 16 and a recording amplifier 17. The low band component of the chrominance signal, obtained by the comb line filter 26 and the band-pass filter 27, is supplied to a subtracter 13, and the high band component of a luminance signal and the carrier chrominance signal is outputted from this subtracter 13. This signal is FM modulated by an FM modulator 15, and is frequency-multiplexed with the converted low band component from the frequency conversion circuit 24, and is recorded on the magnetic tape T.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a color under one type video tape recorder.

[Requirement of the invention]

This invention provides a color under-type VTR in which two cascade-connected subtractive comb filters are provided in the recording system, and the low-frequency components of the color signal that has passed through only one stage of the comb filter are frequency-converted. At the same time, the sum signal of the high frequency component of the color signal and the luminance signal is separated from the composite color video signal using the low frequency component of the color signal that has passed through a two-stage comb filter, and is recorded as an FM signal. By doing so, it is possible to compensate for the delay in the low-frequency component of the reproduced color signal due to the subtractive comb filter for preventing crosstalk from adjacent tracks, and it is possible to support wide-band color video signals. This prevents deterioration of the vertical resolution of the image.

[Conventional technology]

Traditionally, home VTRs have adopted a color under system, in which, during recording, the luminance signal is converted to an FM signal, and the carrier color signal is frequency-converted to a lower frequency range than the FM luminance signal. The converted carrier color signal and the FM luminance signal are frequency-multiplexed and recorded, and the original color video signal is reproduced by performing signal processing that is opposite to that during recording during reproduction.

[Problem that the invention seeks to solve]

By the way, in the case of the NTSC system, as shown in FIG. 3A, the band of the luminance signal Y is about θ to 4.2 MFIZ,
The band of the carrier color signal C is equal to the color subcarrier frequency fsc (each 3.
58MHz) asymmetrically above and below, fsc +0
．． 5MHz.

fsc -1.5MHz.

However, in conventional color under one-type VTRs, due to the lack of recording and playback bandwidth, etc.
The upper limit of the YFMO sideband of the M luminance signal is restricted, and the lower limit of the sideband is restricted to the low-band converted color signal, as shown in Figure B, so the low-band converted carrier color Unable to secure sufficient bandwidth for the signal, +1! The band of the I color sending signal C becomes narrow to about ±0.5 MIIz symmetrically above and below fsc.

On the other hand, the band of the recorded and reproduced luminance signal Y is set as shown in FIG. There is.

Therefore, when a color video signal is recorded and played back using a color under type VTR, a reproduced image is generated.

In particular, there was a problem in that the resolution of color images deteriorated.

In order to solve the above-mentioned problems, the applicant has filed a patent application filed in 1983.
No. 2-66292, the high-frequency components of the luminance signal and the carrier color signal are converted into FM signals and recorded and reproduced at the same time,
A VTR has already been proposed in which the resolution of color images is particularly improved by converting the frequency of the low-frequency components of the carrier color signal to a lower frequency than that of the FM signal for recording and reproduction.

Hereinafter, the already proposed VTR will be explained with reference to FIGS. 4 to 6.

Examples of the configuration of the recording system and reproduction system of the previously proposed VTR are shown in FIGS. 4 and 5, respectively.

In FIG. 4, a composite color video signal (Y+Cw) as shown in FIG. 6A is input from the input terminal +1) to the AGC circuit (
11) and a delay line (12) to a subtraction circuit (13), and is also supplied to a subtraction comb filter (21), where a wideband carrier color signal Cw having a burst signal B is taken out and passed through a bandpass filter. (22). The pass band of this band filter (22) is set narrowly, for example, ±0.3 MHz with fsc as the center. As a result, from the filter (22), as shown in FIG. is taken out, and this signal CL is sent to the switch circuit (1
8) to the subtraction circuit (13).

In this case, the switch circuit (18) is connected to the control terminal (
According to the burst flag from 2), the connection state shown in the figure is set during the non-burst period, and the connection state is switched to the opposite connection state from that shown during the burst period.

Therefore, during the non-burst period, the subtraction circuit (13) subtracts the low frequency component CL from the signal (Y+Cv), so the subtraction circuit (13) outputs the carrier color signal Cw as shown in FIG. A sum signal (Y+CH) of the high-frequency component CH (strictly speaking, the outer band component of the signal CL that is modulated by the high-frequency component of the color difference signal) and the luminance signal Y is extracted, and the sum signal (Y+CH) is extracted during the burst period. Since no subtraction is performed in the subtraction circuit (13), the luminance signal Y having the burst signal B is extracted as shown in the figure.

Then, the signal (Y+CH) from this subtraction circuit (13)
and signal Y are supplied to the group modulation circuit (15) through the pre-emphasis circuit (14), as shown in FIG.
The FM signal distributed on the high frequency side is converted to (Y + CH) FM or (Y + B) FM (hereinafter abbreviated as VCFM),
This FM signal is supplied to an adder circuit (16).

Further, the signal CL from the filter (22) is supplied to the frequency conversion circuit (24) through the 〇〇 circuit (23), and the local oscillation circuit (25) having an AFC/APC configuration.
to frequency (fsc + fn) *For example, fj=43
．． 75fh (every 688KHz, f h is horizontal frequency)
The local oscillation output of signal CL is supplied to the frequency conversion circuit (24), and as shown in FIG.
SC is converted to fn, and this converted signal CL is supplied to an adder circuit (16).

Therefore, as shown in FIG. E, the adder circuit (16) outputs a frequency multiplexed signal (VCFM+C
L) is taken out.

This signal (VCFM+CL) is then supplied to the rotary magnetic heads HA and HB through the recording amplifier (17), and is recorded on the magnetic tape T as one diagonal magnetic track for each field period and as a guard track. The data is recorded sequentially in bands.

On the other hand, in FIG. 5, signals (YCFM+CL) are reproduced from heads HA and IIB. However, in this case, the signals Y, CH, and CL in this reproduced signal have jitter, and each synchronization frequency is the normal frequency fh, fs.
Frequency with jitter fhj, fscj from c, fn
.

fnj.

Then, the reproduced signals from the heads IIA and HB are supplied to the bandpass filter (32) through the regenerative amplifier (31) to extract the FM signal VCFM, and this signal VCFM is supplied to the FM demodulation circuit (34) through the limiter (33). The signal (Y+CH) is demodulated during the non-burst period, and the signal Y is demodulated during the burst period.

These signals (Y10H) and signal Y are supplied to the switch circuit (36) through the de-emphasis circuit (35).

This switch circuit (36) is controlled by a burst flag from a control terminal (3), and is in the illustrated connection state only during a non-burst period to output an input signal. Therefore, the signal (Y+CH
) are extracted. Note that this signal (Y+CH) has jitter as described above, and each synchronization frequency is fhj,
fscj.

In addition, the signal (VCFM +
CL) is supplied to a low-pass filter (41) to extract a low-pass component CL (color subcarrier frequency is fjj) of the carrier color signal C, and this signal CL is passed through an ACC circuit (42) to a frequency conversion circuit (43). Although the details will be described later, a local oscillation output of a jittery frequency (fscj + fnj) is supplied from the second frequency conversion circuit (44) to the frequency conversion circuit (43), and the signal CL is Carrier frequency fjj is converted to carrier frequency fscj, and this frequency-converted signal CL is supplied to an adder circuit (37).

Therefore, in the adder circuit (37), the signal (Y+C
Since H) and signal CL are added, the addition circuit (37)
The original color video signal (Y+Cw) is extracted from. However, this signal (Y + Cν) has jitter, and each synchronous frequency has frequencies fhj, fscj
It is.

Therefore, this signal (Y+cv) is
), and the original color video signal (Y+Cv) without jitter is taken out at the output terminal (4).

Then, the local oscillation output having jitter as described above is generated by two oscillation circuits (50) having an AFC/APC configuration.

(60) as follows.

That is, the signal (Y
+CH) and signal Y are supplied to a synchronization separation circuit (51), a horizontal synchronization signal with frequency rhj having jitter is extracted and supplied to a first oscillation circuit (50).

Also, the signal (Y+C) from the de-emphasis circuit (35)
M) and signal Y are supplied to a burst gate circuit (56) to generate a burst signal B of frequency fscj with jitter.
is taken out and supplied to the oscillation circuit (50).

As a result, the oscillation output of the first oscillation circuit (50) has a frequency fscj and a phase having jitter corresponding to the jitter of the signal (Y+CH) from the de-emphasis circuit (35), and is transmitted to the frequency conversion circuit (44). Supplied.

Furthermore, the signal (Y+C) from the de-emphasis circuit (35)
H) and signal Y are supplied to the synchronous separation circuit (61),
A horizontal synchronizing signal having a frequency fhj having jitter is extracted and supplied to the second oscillation circuit (60).

Further, the signal CL from the frequency conversion circuit (43) is supplied to the burst gate circuit (66), a burst signal B having a frequency fscj having jitter is taken out, and this burst signal B is supplied to the oscillation circuit (60). Ru.

As a result, the oscillation signal of the second oscillation circuit (60) becomes a frequency fij having jitter, and the oscillation signal of the second oscillation circuit (60) becomes the frequency fij having jitter.
4).

Therefore, in the conversion circuit (44), the reoscillation circuit (5
Frequency addition of the oscillation outputs of 0) and (60) is performed, and the conversion circuit (44) outputs a frequency (fscj
The local oscillation output of +fjj) is taken out, and as a result, the frequency of the signal CL is converted in the first frequency conversion circuit (43) as described above.

Therefore, with respect to the signal CL from the frequency conversion circuit (43), the first oscillation circuit (50) generates an oven signal based on the horizontal synchronization signal and burst signal of the output signal (Y+CH) of the de-emphasis circuit (35). Loop AFC
/APC operation is performed, and the second oscillation circuit (6
0), a closed-loop Arc
/APC operation is performed, so the signal (Y+C)l) supplied to the adder circuit (37) and the signal CL have equal jitter, and the adder circuit (37) outputs a The original broadband carrier color signal Cw, in which the frequency component CH and the low frequency component CL are correctly combined, and the luminance signal Y
is taken out.

By the way, in the above-mentioned existing proposals, guard bands are formed between tracks, but when performing so-called azimuth recording without forming guard bands between tracks, such as in 8 mm video, the well-known method is used. Thus, if a subtractive comb filter is provided at the next stage of the frequency conversion circuit (43) in the reproduction system, crosstalk from adjacent tracks to the reproduced color signal can be removed.

However, since this comb filter has an IH delay line, a problem arises in that the vertical resolution of the reproduced color image deteriorates.

In view of the above, an object of the present invention is to provide a video tape recorder that can handle wideband color video signals and prevents deterioration of the vertical resolution of reproduced color images during high-density recording.

[Means for solving problems]

The present invention provides subtractive first and second comb filters (2
1) and (26) are connected in cascade to supply a composite color video signal, frequency converting the low frequency component CL (IH) of the carrier color signal obtained from the output of the first comb filter,
The low frequency component CL(211) of the carrier color signal obtained from the output of the second comb filter is subtracted from the composite color video signal to obtain the luminance signal Y and the high frequency component Cw CL(2) of the carrier color signal.
11), record the FM signal of this sum signal and the frequency-converted low-frequency component on a magnetic tape, and reproduce the FM signal and the frequency-converted low-frequency component from this magnetic tape. , Regenerated F? The l signal is demodulated to obtain a sum signal of the luminance signal and the high frequency component of the carrier color signal, and the reproduced low frequency component is reconverted to the original frequency band, and this reconverted low frequency component CL This is a video tape recorder in which (Il+) is added to a sum signal of a luminance signal demodulated via a subtractive comb filter and a high frequency component of a carrier color signal.

[Function] According to this configuration, during high-density recording, the delay of the low frequency component of the reproduced color signal due to the comb filter for preventing crosstalk from adjacent trunks is compensated for, thereby reducing the deterioration of the vertical resolution of the reproduced color image. is prevented.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a video tape recorder according to the present invention will be described below with reference to FIGS. 1 and 2.

The configurations of a recording system and a reproducing system according to an embodiment of the present invention are shown in FIGS. 1 and 2, respectively.

In FIG. 1, (1) to (25) correspond to each part of the previously proposed example shown in FIG. 4 mentioned above.

(26) is a second subtractive comb filter, to which the output of the first subtractive comb filter (21) is supplied in common with the bandpass filter (22);
The output of is passed through the bandpass filter (27) to the switch (
18) is supplied to the movable contact. Double band filter (22
) and (27) are assumed to have the same characteristics. The rest of the configuration is the same as that shown in FIG. 4 above.

Also, in Figure 2, (3) to (44), (50)
-(66) correspond to each part of FIG. 5 mentioned above.

(45) is a third subtractive comb filter, which is inserted between the frequency conversion circuit (43) and the addition circuit (37). The rest of the configuration is the same as that shown in FIG. 5 above.

The operation of this embodiment is as follows.

In the recording system shown in FIG. 1, the low frequency component CL of the carrier color signal taken out from the bandpass filter (22) is delayed by IH by the square filter (21).
(IH), the second bandpass filter (27)
The low frequency component CL of the carrier color signal extracted from the carrier color signal is further delayed by 1 (CL(2)I) by the second comb filter (26), so it is expressed as CL(2)I).

In the subtracter (13), this low frequency component CL (211)
is subtracted from the composite color video signal Y + Cv, and the high frequency component of the I-cross color feeding signal taken out from the subtracter (13) becomes CM = Cw CL (2H). This is converted into an FM signal together with the luminance signal Y, frequency-multiplexed with the converted low-frequency component CL (IH) from the frequency conversion circuit (24) in the adder circuit (37), and recorded on the magnetic tape T.

In the playback system shown in Figure 2, this tape T is played back,
Along with the luminance signal Y, Cv-CL (2H) is taken out from the switch (36) as the high frequency component CH of the carrier color signal.

On the other hand, the low frequency component CL (IH) of the carrier color signal taken out from the frequency conversion circuit (43) is further delayed by IH by the third comb filter (45), and the low frequency component CL (2
H) becomes.

As mentioned above, the high frequency component Cw-CL (2
H) and low frequency component CL (2H) are added to the adder circuit (37).
When added at 2■ delayed low frequency component CL
(2) 1) is canceled out, and the amount of delay between the high-frequency component and the low-frequency component of the carrier color signal does not differ through the recording system and playback system as in the previously proposed VTR, and the original Since the broadband carrier color signal Cw is reproduced, the vertical resolution of the color image is not degraded.

For simplicity, a regeneration comb filter (45) is used.
Although different symbols are used for the recording system comb filters (21) and (26), it is of course possible for either one to be used as the other.

〔Effect of the invention〕

As detailed above, according to the present invention, two cascade-connected
A multi-stage subtraction type (a comb-shaped filter is provided in the recording system, and the low-frequency components of the color signal that has passed through only one stage of the comb-shaped filter are frequency-converted and recorded, and the color signal that has passed through the two-stage comb-shaped filter is Since the sum signal of the high frequency component of the color signal and the luminance signal is separated from the composite color video signal using the low frequency component and recorded as an FM signal, a subtractive type signal is used to prevent crosstalk from adjacent tracks. A color under one-type system that compensates for the delay in the low-frequency components of the reproduced color signal caused by the comb-shaped filter and is compatible with wideband color video signals, as well as preventing deterioration of the vertical resolution of the reproduced color image during high-density recording. A video tape recorder is obtained.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing the configuration of a recording system and a reproducing system, respectively, of an embodiment of a video tape recorder according to the present invention, and FIGS. 3 and 6 are frequency layouts for explaining the present invention, respectively. FIGS. 4 and 5 are block diagrams respectively showing configuration examples of a recording system and a reproducing system of a previously proposed video tape recorder. (15) is an FM modulator, (21), (26),
(45) is a subtractive comb filter, (24) , (
43) is a frequency converter, and (34) is an FM demodulator.

Claims (1)

[Claims] First and second subtractive comb filters are connected in cascade to supply a composite color video signal, and a low frequency component of a carrier color signal obtained from the output of the first comb filter is provided. At the same time, the low frequency component of the carrier color signal obtained from the output of the second comb filter is subtracted from the composite color video signal to obtain a combination of the luminance signal and the high frequency component of the carrier color signal. Obtaining a sum signal, recording the FM signal of this sum signal and the frequency-converted low-frequency component on a magnetic tape, and reproducing the FM signal and the frequency-converted low-frequency component from the magnetic tape, The reproduced FM signal is demodulated to obtain a sum signal of the luminance signal and the high frequency component of the carrier color signal, and the reproduced low frequency component is reconverted to the original frequency band. A video tape recorder characterized in that the converted low-frequency component is added to the sum signal of the demodulated luminance signal and the high-frequency component of the carrier color signal via the subtractive comb filter.