JPS5983490A - Recorder of color video signal - Google Patents

Abstract

PURPOSE:To compensate the time axis fluctuation of a recording signal due to unevenness of rotation of a head, by detecting a rotating frequency of the rotary head and using this detecting signal as a carrier signal in forming a low converting chrominance signal. CONSTITUTION:A recording signal appearing at an output terminal 22 of a recording amplifier 21 is applied to rotary heads 23A, 23B and recorded on a magnetic tape 25. A magnetic disc 28 is fixed to a drum rotary shaft 26 of the rotary head and a magnetism sensor 29 is provided near the disc 28. A detecting signal from the sensor 29 is applied to PLL circuits 31, 32 via a waveform shaping amplifier 30. The PLL circuit 31 generates a sub-carrier signal, which is applied to balancing modulation circuit 3, 4, the PLL circuit 32 generates the carrier signal having, e.g., 175fH/4 (fH: horizontal scanning frequency) of low converting frequency, and the signal is applied to a circuit 8 converting the chroma signal into the converted chroma signal of the low carrier frequency via a switch circuit 33.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a color video signal recording device that is applied to a device in which a color imaging device and a rotary head type VTR are integrated.

"Background Art and Its Problems" FIG. 1 shows one possible configuration when recording the output of a color imaging device using a rotating head type VTR.

In FIG. 1, reference numeral 1 indicates an image pickup tube (~, whose image pickup surface is provided with an optical filter for color separation and an index electrode. The 1° signal extraction unit 2 is supplied with a luminance signal Y, a red color difference signal R-Y, and a blue color difference signal B-Y. The color imaging device is composed of a low-pass filter, an IH delay circuit for extracting color difference signals, a phase detection circuit, etc. This color imaging device is called an electronic index phase separation method.

The color difference signals R-Y and B-Y are processed by the balanced modulation circuit 3゜4.
are supplied respectively. The balanced modulation circuit 4 has a frequency fsc (3.58 Ml (z
) are supplied to the balanced modulation circuit 5, and the subcarriers having a relative phase difference of 90' are supplied to the balanced modulation circuit 5 by a phase shifter 6. The outputs of these balanced modulation circuits 3 and 4 are supplied to a mixing circuit 9 via a bandpass filter 7.8. In this mixing circuit 9, a burst signal from a terminal 10 is also added, and its output is supplied to a mixing circuit 11, to which a luminance signal Y and a synchronization signal from a terminal 12 are added.

A composite color video signal is then obtained at the output terminal 13 of the mixing circuit 12.

This composite color video signal is supplied to a low-pass filter 14 and a band-pass filter 15, and is separated into a luminance signal and a carrier color signal. This separated luminance signal is supplied to a luminance signal recording circuit 16. Luminance signal recording circuit 16
It consists of a Nori-emphasis circuit, a clip circuit, a flange circuit, an FM modulation circuit, and a bypass filter.
The output KFM modulated j11 signal appears, and this modulated luminance signal is supplied to the mixing circuit 17.

Further, the carrier color signal separated by the bandpass filter 15 is supplied to the frequency converter 18 . A carrier signal for low frequency conversion is supplied to this frequency converter 18 from a carrier 3 generation circuit 19 . A low-pass filter 20 is provided at the output of the frequency converter 18, and the output of the low-pass filter 20 is supplied to the mixing circuit 11. The output of this mixing circuit 17 is taken out to an output terminal 22 via a recording amplifier 21. This output terminal 22 is provided with two rotary heads 1 via a rotary transformer (not shown), and these rotary heads record the recording signal for one field as one video track. Ru.

In order to perform high-density recording without providing guard bands between adjacent video tracks, the direction in which the gap between the rotary heads forming the adjacent 10,000 video tracks extends, and the other video track 1 The extending direction of the gap of the rotary head forming the rotary head is different from that of the rotary head. In this way, by recording with two rotary heads whose gap propagation directions are shifted from each other, crosstalk from adjacent trunks can be suppressed during playback.

-4= This suppression of crosstalk using azimuth loss is effective for modulated luminance signals, but does not hold true for converted color signals with low frequencies. Therefore, the converted color signal is
Fully control the phase or frequency of the carrier signal for low frequency conversion,
Crosstalk from adjacent tracks is removed by a comb filter provided in the reproduction circuit.

In the configuration shown in FIG. 1, the subcarriers from the terminal 5 are generated by a stable oscillator such as a crystal oscillator, and the carrier signal for low frequency conversion formed by the carrier generation circuit 19 is also generated by a stable oscillator such as a crystal oscillator. It is formed using the above-mentioned subcarriers. Therefore, the recorded signal should have no time axis fluctuations. However, due to jitter due to uneven rotation of the rotating head,
The recorded signal includes time axis fluctuations. When the magnetic chip 79 recorded in this manner is reproduced, the reproduced signal contains not only the jitter that occurs during reproduction, but also the time axis variation added during recording as described above.

−[As HJ, uneven rotation of the rotating head during recording, =
5 - Assuming that a time axis variation of ε is included due to unevenness in the running speed of the magnetic tape, etc., the frequency of the subcarrier on the recording pattern is fr.

(1+ε).

``Object of the Invention'' The overall object of the present invention is to realize a color video signal recording apparatus in which the influence of jitter during recording is reduced.

"Summary of the Invention" The present invention reduces the influence of jitter during recording in color signal processing. This invention detects the rotational frequency of a rotating head, supplies this detection signal to a frequency multiplier circuit or a PI loop circuit, and uses the output signal of the frequency multiplier circuit or PLL circuit as a carrier in the process of forming a low frequency conversion color signal. It is designed to be used as a signal.

``Example'' Hereinafter, a second example of an example applied to a color video signal recording apparatus having the configuration shown in FIG. 1 will be described.
This will be explained with reference to the figures.

A recording signal appearing at the output terminal 22 of the recording amplifier 21 is supplied to the rotary heads 23A and 23B, and the tape guide drum 2
The information is recorded on a magnetic tape 25 wound around 40 circumferences. The rotating heads 23A and 23B are connected to the tape guide drum 24.
(e.g., the upper drum).

This drum rotating shaft 26 is directly connected to the rotating shaft of a drum motor 27, and is rotated at the frame frequency of the rotating heads 23A, 23Be, so that the rotating heads 23A, 23B
Recording signals for one field are alternately recorded from the VC.

Then, the magnetized disk 28 is fixed to the drum rotating shaft 26. The circumferential surface of the magnetized disk 28 is magnetized at a predetermined pitch.

A magnetic sensor 29 (magnetoresistive element, Hall element, etc.) is provided adjacent to the magnetized disk 28, and a detection signal of a predetermined frequency (fT) is obtained from this magnetic sensor 29.

This detection signal is supplied to a PLL circuit 31 and a PLL circuit 32 via a waveform shaping amplifier 30. One PLL circuit 31 generates a subcarrier signal of frequency fsc, and the other one generates a subcarrier signal. The subcarrier signal from this PLL circuit 31 and the subcarrier signal phase-shifted by Th90' are supplied to balanced modulation circuits 3 and 4,
It is modulated by color difference signals R-Y and B-Y. Also, P
The output signal of the LL circuit 32 is supplied to one input terminal of the switch circuit 33, and is also phase-inverted by the inverter 34 and supplied to the other input terminal.

This switch circuit 34 is controlled by a switching pulse from a terminal 35. This switching pulse has a constant level in one field, and the level inverts every horizontal period in the next field. By subjecting the recorded color signal to phase inversion processing in this manner, the crosstalk components of the color signal occurring between adjacent tracks can be removed by a comb filter provided in the full reproduction system.

If jitter ε (a function of time) exists in the rotational speed V of the rotating drum (the drum to which the rotating heads 23A and 23B are attached) during recording, the running speed of the magnetic tape 25 will vary from the rotational speed V. Since the relative velocity between the rotary heads 23A and 23B and the magnetic tape 25 is sufficiently small compared to the above, the relative speed is v(1+ε).

In the embodiment of the present invention described above, the magnetic sensor 29 generates a detection signal with a frequency of fT (1+g), and PL
The L circuit 31 generates a subcarrier signal with a frequency of fsc (1+ε'), and the PLL circuit 32 generates a subcarrier signal with a frequency of fsc (1+ε'). (1
+g') (however, fc-fsc + fr,) a conversion carrier is generated. In the frequency converter 18, foC1+g') -, fsc(1+g')-fj
A frequency conversion operation of (1+g') is performed. Therefore, one wavelength λ of the low frequency conversion color signal recorded on the magnetic tape 25 is ('÷ε'), so that the influence of jitter on λ can be reduced.

9--FIG. 3 shows another embodiment of the invention. In this example,
When performing quadrature two-phase modulation on the color difference signals RY and BY' appearing from the signal extraction section 2, a low frequency carrier is used as the subcarrier.

Similar to the previous embodiment, the detection signal of the magnetic sensor 29 via the amplifier 30 is supplied to the PLL1 path 32,
A carrier with a low frequency fL is formed by the LL circuit 32. This carrier is subjected to phase inversion processing by a switch circuit 33 and an inverter 34, and then a balanced modulation circuit 4
It is also supplied to the balanced modulation circuit 3 via the phase shift circuit 6. The output of this balanced modulation circuit 3.4 is supplied to a mixing circuit 9, and the output of this mixing circuit 9 is supplied to a mixing circuit 17 via a low-pass filter 20.

In this mixing circuit 17, the signal is mixed with the FM modulated luminance signal and taken out via the recording amplifier 21 to the output terminal 22.

In the embodiment shown in FIG. 3, the number of frequency converters and filters can be reduced compared to the configuration shown in FIG.
In addition to simplifying the configuration, the quality of the recorded signal can be improved. Furthermore, the frequency f of the detection signal obtained from the magnetic sensor 29
Since T cannot be set to a high frequency, it is difficult to form a subcarrier fsc. However, other embodiments of the present invention have the advantage that such problems do not occur because it is sufficient to form carriers of low frequencies.

"Application Example" In addition to the PLL circuit, a frequency multiplier circuit may be used to form a subcarrier and a carrier for low frequency conversion from the detection signal.

In addition, in order to eliminate crosstalk of color signals between adjacent tracks, the present invention is configured such that the phase of the carrier is changed by 90° in total.
It can also be applied to a case where the phase shift is shifted every horizontal period and the direction of this phase shift is reversed between adjacent tracks.

Furthermore, it has an all-in-one configuration with a color video camera and VTR,
A magnetic chain 7'' is wound around the tape guide drum, for example, over 300', and scanning of the effective screen of a color image pickup tube is generated by one head rotating at the field frequency (or two rotating heads with different azimuthal gaps). The present invention can be applied to a color video signal recording apparatus having a tape guide drum having a small diameter, and can be reproduced by an existing rotary two-head VTR.

The present invention may be fully applied when the color video signal is of the PAL system.

"Effects of the Invention" According to the present invention, even if jitter is present during recording, the entire color video signal can be recorded so that the carrier of the color signal has a regular frequency in the recording pattern formed on the magnetic tape.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an example of a color video signal recording device to which the present invention can be applied, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 3 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of another embodiment of the present invention. 1...... Image tube, 3, 4...
・・・・・・Balanced modulation circuit, 16・・・・・・・・・
...Brightness signal recording circuit, 23A, 23B...
. . . Rotating head, 25 . . . Magnetic tape, 29 . . . Magnetic sensor, 31.
32・・・・・・・・・PLL circuit. Agent Masato Sugiura 13- Fig. 1 1% Kaisho 59-83490 (5) Fig. 2 + -Y MOD + LPF Y, REC914 -Y BPF LPF + 4 8 1582017 9σ 33 5 6 U7'r5'' ″
″ ”°′−〒

Claims (1)

[Claims] In a video signal recording device in which a color imaging device and a rotary head type VTR are operated by a common synchronizing signal, the color signal from the color imaging device is converted to a converted color signal of a low carrier frequency. a conversion circuit for performing full FM modulation of the luminance signal from the color imaging device;
a modulation circuit, a rotary head for recording a recording signal in which the converted color signal and the FM modulated luminance signal are mixed on a magnetic tape, a detector for detecting the rotational frequency of the rotary head, and a detector for forming the converted color signal. A recording device for color video signals, which is equipped with a circuit that forms all the carrier signals required for the output signal from the above-mentioned detector.