JPS58188324A - Video tape recorder - Google Patents

Abstract

PURPOSE:To attain ease of insert recording even for a VTR having no fixed head, by winding a video tape on a rotary cylinder by >=200 deg., taking a video signal frequency-modulated on a video track formed at a region being >=200 deg. as a bias, and recording a pilot signal. CONSTITUTION:The video tape 2 is wound on the rotary cylinder by 205 deg.-220 deg. to for a over-track 11 with alpha (=15-30 deg.), and the pilot signal taking the frequency-modulated video signal as a bias is recorded. Since a video head 6 reads out the pilot signal on the over-track 11 at the insert recording, the insert video recording is done easily even for the VTR having no fixed head.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new recording method for a video tape recorder (particularly concerned with a video signal distribution method that does not require a fixed head and is capable of in-lt-i+ recording).

The fixed heads required in conventional video tapes are an audio signal head and a tracking/trawl head. In order to eliminate the audio signal head, it has been known for a long time to record the audio signal in a video track by frequency multiplexing it. A method for removing the control head is known as the V-2000 method that uses pilot signals.

The problem here is that if the control head is removed in the V-2000 system, insert recording cannot be performed.

This problem will be explained in detail below.

Insert recording is a technique for partially re-recording a recorded tape in order to insert titles and other information later.

Specifically, you need to do the following: First, a playback state is entered, a normal tracking operation is performed, and the insert start point is reached. At the insert start point, the video head is switched from the playback state to the recording state, and recording continues until the insert end point. At the insert end point, the video head is switched from the recording state to the playback state, and the insert operation is completed.

The important technical issues in insert recording are the insert starting point,
The question is whether to connect the vertical synchronization phase and the video track phase to η1 at both end points. In a video chip recorder having a control head, the above technical problem is achieved by keeping the tracking control circuit (servo circuit) always in the reproducing state and keeping only the video head operation in the recording state only during the insert period.

However, in the V-2000 system, there is no control head, and the pilot signal for tracking control is read out by the video head, so when the video head is switched to the recording state, the pilot signal cannot be read out. Therefore, although there is no problem at the insert starting point, the phase connection at the insert starting point is not ensured and the reproduced image is disturbed.

Figure 1 shows the input to the rotating cylinder in V-2000.
Figure 2 shows the tape pattern of V-2000.

#! In FIG. 1, 1 is a rotating cylinder, 2 is a video tape, 3 is a video cassette, and 6 and 7 are (2) rotating video heads. In the V-2000 system, tape input and output 11
There is an overramp of approximately 5° per frame, totaling 190°.
It is wrapped around.

In FIG. 2, numeral 4 is a video track written on a rotating video with a gutter 6, and 5 is an audio track written with a fixed head. As shown in the figure, pilot signals of four different frequencies are written on video track 4.

Suppose now that the video head 6 is tracing the video track on which the pilot signal of f3 was recorded. In this case, the pilot signal read out by the video head 6 is f2. f3. It becomes f4. Therefore, by performing tracking control so that the magnitudes of f2 and f4 are equal, accurate track tracing can be performed.

The problem here is that in order to perform accurate track tracing, the video head 6 must read the pilot signal written on the video track 4.

At the insert start point mentioned above, the video recorder/node 6 is reproducing the pilot signal until just before that point, so it is possible to connect and record the vertical synchronization at the seam, the video track pattern, the pilot signal order, etc. ! : is possible.

17, tracking control using pilot signals cannot be performed during insertion, and only control is performed to keep the tape speed constant. For this reason, if insert number 4 < son number 3, insert recorded video? Disconnectivity occurs in the vertical synchronization phase, video track phase, pilot signal 11, number 6, etc. between the pre-recorded video tracks when adjusting the track. When playing this L phase discontinuous videotape,
The last child of the above insert causes screen disturbances.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the drawbacks of the prior art described above, and to provide a video recorder that records a 4F tape pattern without a conte/coal head and is capable of insert sickle printing.

In accordance with the present invention, a videotape is placed in two parts in a rotating cylinder.
It is wound around 05° to 220° to form video tracks corresponding to 205J to 2200. Then, a pilot signal is recorded on all video tracks using the same wave number modulated video signal as a bias. By doing so, during insert recording, it is possible to reproduce the video trunk in the overlap portion of 15 to 30 degrees formed in excess and read out the pilot signal.

Hereinafter, an example of the present invention will be described. This will be explained with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing a mechanism for winding a tape around a rotating cylinder used in the present invention.

In Fig. 3, is approximately 190°, is 15° to 30°, and the total winding angle is 205° to 220°. 8 in FIG. 3 is an audio head provided as an option.

FIG. 4 is a diagram showing an example of the tape pattern of the present invention produced by the mechanism shown in FIG. 3. 9 and 10 in Figure 4
is an obscene track that does not specify a purpose. This portion is a tape edge, which is a dead space that is difficult for a rotating head to record.

θ in FIG. 3 corresponds to video track 4 in FIG. 4, and numeral θ in FIG. 3 corresponds to overlap track 11 in the fourth section.

In FIG. 4, at least a frequency-modulated luminance signal and a pilot signal are recorded on the video track 4 and the overlap track 11. ! (Approximately 5 minutes from the boundary between video track 4 and O74-lap trunk 11)
H~about 8H!・) will be recorded.

FIG. 5 is a diagram showing an example of a tape pattern after insert recording of the tape (FIG. 4) recorded with the video tape recorder of the present invention.

In FIG. 5, the shaded track 137'<
This shows a track that has been re-recorded using insert recording.

In FIG. 5, both video heads 6 and 7 are in the playback state up to the insertion start point, and normal tracking operations are performed.

When the insert starts, the video controller 6.7 puts the overlap track 11 in the playing state while tracing, and
While the video track 4 is being traced, it is controlled to be in a recording state. By doing so, the pilot signal can be reproduced, albeit intermittently, even during insert recording, so that normal tracking operation can be performed. Therefore, even at the insert end point, the video track phase, vertical synchronization phase, pilot phase, etc. can be made continuous, and no screen disturbance occurs when this tape is played back.

Insert functionality is not a necessary feature for all videotape recorders. However, it is desirable that any tape recorded with any video tape recorder be capable of insert recording using a video tape recorder with an insert function, and it is important to form the tape pattern shown in FIG. 4.

FIG. 6 is a diagram showing an example of a tape pattern diagram when audio is further after-recorded on the insert-recorded tape (FIG. 5).

In Figure 6, the horizontally lined track 14 is a PCM audio track formed by the video heads 6 and 7 by after-recording. When recording an audio signal by converting it into PCM and time-compressing it, in the case of 2ch audio, 15° is required in the case of 3001 chfi-voice.

At 8 in FIG. 6, the video head 6.7 is in the playback state while tracing the video track 4, and in the recording state while tracing the overlap track 11 (that is, the PCM audio track 14). By reproducing the video track 4, the S pilot signal can be reproduced, thus allowing normal tracking operation.

Pilot signals in the order shown in Figure 6 are also recorded on the PCM audio track 14 so that the videotape in Figure 6 can be further inserted recorded.

Should.

The PC+4 audio track 14 is formed on the automatic wrap track 11 by overwriting it. The luminance FM signal is easily erased by overwriting, but the pyro signal and low-frequency conversion chroma signal are not erased very much. Pyrog l-
Unerased signals do not pose much of a problem since the same signal is re-recorded.However, unerased chroma signals interfere with the PCM audio signal and tend to degrade the error rate of the PCM decoding circuit. Therefore, it is desirable to select a PCM recording method that is less susceptible to the effects of unerased chroma signals.

Alternatively, it is also conceivable not to record the chroma signal on the overlap track. Dayme IJ in this case
y l- has a slight recording circuit! jI is to become sloppy.

Another solution would be to provide a fly erase head in advance of the video head 6.7 to sufficiently reduce the amount of chroma signal left unerased.

FIG. 7 is a diagram showing another row of tape pattern diagrams when audio is further recorded after insert recording 1Ikl completed 6 tapes.

In FIG. 7, reference numeral 15 indicates an audio track formed by the fixed audio head 8. In FIG. If the audio track 15 is 2ch, then the area occupied on the tape is approximately 30° in terms of pivot points, and 1ch is approximately 15°.

A feature of FIG. 7 is that since the overlap track 11 has been rewritten to the audio track 15, insert recording is no longer possible. Therefore, the seventh
When performing audio after-recording as shown in the figure, insert recording must be performed prior to this.

FIG. 8 is a block diagram showing a main part of an embodiment of a recording circuit of a video tape recorder used in the present invention, and FIG. 9 is a waveform diagram of each part in FIG.

In FIG. 8, reference numeral 16 denotes an input of a voice signal, and 118 denotes an F'M audio signal generation circuit, which outputs a continuous signal such as 40. 17 is a video signal input terminal, 19 is F
'A continuous signal like 39 is obtained in the MJ degree signal generation circuit. 20.22 is a low-conversion chroma signal generation circuit which generates a signal 41 at its output.

21 is a converter, 25 is a BPF', 26 is a converter, and 27 is a phase shift circuit. In NTSC, no phase shift is performed on the first track, and a 180° phase shift is performed on the @2 track every half period of water. Do (PAL(ζ
In this case, no phase shift is performed on the first track, and the second
28 is a frequency divider and the NTSC
In the case of ↑ (PAL II coalescence, even N'rSC, 29
f) For i378fHVco, ~), for NTSC with 29iVCO, the oscillation frequency is 189fH (fn is the horizontal synchronization frequency) (for PAL, the oscillation station wave number is 375fH)
, 378fH in the case of NTSC), 3
0 is a phase comparator, 31 is a sync separation circuit, and 27.30 supplies a horizontal sync pulse. 32 is a frequency divider, and in the case of NTSC, (29 is 189 even in the case of -1NTSC in the case of PAL)
375378
fuV CO(1)Ijh union), 33, 34,
35.36 is a frequency divider for generating a via 80ft signal. Hao”s7+,
6 #,; 14j> f! In the case of NTSC, the output of the switch 37 is fl"II -2i-, fHW
6.517fH, fHwm ] "fHwm 7.56
fH, fs mI B f ” Toxic 10.50 f t
l, f 4 ++ s+ 1Ef n ax g. 45f
H (for PAL, fI ”, -, -, fH = 6.466
fH, fHW, fHm 7.5QfH.

f3 2 茫fH=10.417fH%f4z -茫fH-
9,375f [()'s pyro y) signal 42 is obtained. 23
is a distribution amplifier, 24 is a rotary transformer, and 38 is a frame pulse input terminal, which receives a pulse 38 from the servo circuit of approximately 30Hz for NTSC (approximately 25Hz for PAL).
is supplied.

When two video heads 6.7 are driven in parallel by one recording amplifier 23 as shown in Figure JJrB, the video head // formed by the video heads 6.7 becomes 43.
44, the pilot signal of overlap track 4 and the video track 4 signal are different. 1 @4 When installing the oval lap track 11 at the leading Beaucilon of the video track 4 as shown in the figure,
The pilot signal frequency of the overlap track 11 is a frequency -° ahead of the pilot signal of the video track 4.

When installing the overlap track lli video track 4 on the trailing beautiful run, - what is the upper d self]
The pilot signal frequency written on the overlap track becomes the next Aid of the video track.

10 is a circuit diagram showing an embodiment of a recording amplifier used in the present invention.

In the resistance diagram 10, 39 is a circuit that mixes the low frequency conversion chroma signal 41, pilot signal 42, and FM audio signal 4o, 41 is a variable resistor that collectively adjusts the recording current of the above three signals, and 4o is a luminance FM signal. Set the record of C
This is a variable resistor. Ql is a recording current supply transistor for the luminance PM signal, and Q2 is a recording current supply transistor for the chroma, audio, and pilot signals. Qi,
A signal voltage of 3 to 4 VpP is required to the collector of Q2 (from the 611 amplifier to the inductance of 3 to 5 μH when looking at the rotary transformer, we try to minimize the energy consumption in the form of a class A amplifier. It is desirable to increase the dynamic range by selecting and Vcc as low as possible, and by setting the dummy negative # to an inductance of 42.Furthermore, reduce the idle current.When the idle current is reduced, the nonlinearity of the recording amplifier causes intermittent hearing, resulting in disturbances. For this reason, separate numbers are provided for Ql and Q2.The signal level of Q2 is fa compared to Ql, and the γ idle current of Q2 does not cause any problem even if it flows sufficiently, so the three signals are Mix and Q
Amplify with 2. Qs, Q4, and Q5 are electronic switches for switching between recording and reproduction. If the collector of Qs is connected to the collector of Ql, a large current will flow through the inductor 42 at t15 during PB, so the DC cut capacitor 4
There are 4. - A resistor 43 is provided so that RECIIIQ3 does not become conductive due to the signal voltage.

In FIG. 10, the recording current frequency characteristic of the FM signal is almost flat.

11 is a circuit diagram showing another embodiment of the recording amplifier used in the present invention.

Reference numeral 45 in 3 in FIG. 11 is a summing amplifier, which mixes and outputs an FM brightness signal 39, an FM audio signal 40, a chroma signal 411, and a pilot signal 42. transistor Q
61Q7, Qs is 8th grade pushpull record 4rump.

The characteristic of FIG. 11 is that even if the idle current is small, the distortion is small and it is easy to reduce the power, but on the other hand, in order to extract a signal output of 3 to 4 Vppc7), approximately VCc+w9V is required. Further, in FIG. 11, since the video head, which is an inductance load, is driven by a constant voltage circuit, it is suitable for the case where the recording current frequency characteristic of the luminance FM signal is made into a low frequency emphasized type.

The tape recorded with the video tape recorder of the present invention can easily be inserted into a video tape recorder without a fixed head.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional tape winding mechanism, FIG. 2 is a plan view of a conventional tape pattern, FIG. 3 is a block diagram showing an example of the tape winding mechanism of the present invention, and FIG. FIG. 5 is a plan view showing an example of the tape pattern after insert recording of the invention, and FIG. 6 is a plan view showing an example of the tape pattern of the invention after insert recording. Figure 47 is a plan view showing an example of the tape pattern of the trowel after performing the /er/er lid recording. 8 is a block diagram showing the main parts of an embodiment of the 2-imaginary circuit used in the present invention, FIG. 9 is a waveform diagram showing the waveforms of each part of FIG. 8, and FIG. , FIG. 11 is a diagram II!l1118 showing an embodiment of the recording amplifier used in the present invention. 1. Circulation cylinder 2. Video tape 4.
・Bi/Odorak 11 ・・1-Bar rough butt rack 39- F″M, 1xiN No. 42 ・・Pa-1 1ko) To wound Thread 1] O 2nd 5th mouth 10 O b Eye off

Claims (1)

[Claims] A-sho, which wraps the tape over 200 degrees around the rotating roller,
A winding of approximately 190 degrees is provided with a writing device that forms a video hook corresponding to a corner, and a winding of approximately 10 degrees or more is provided with a writing device that forms an overlap track corresponding to a corner, and the video track is provided with a writing device that forms a video hook corresponding to a corner. A video tape recorder which aims at writing a pilot signal into the overrun track using at least an FM luminance signal as a bias.