JPS6027094B2 - How to adjust a magnetic recording/playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a one-head rotating magnetic green image reproduction system (hereinafter referred to as VT).
(referred to as R), and provides a method for accurately and easily adjusting and setting the mounting positions of the control head and the audio head.

In other words, the tape recorded on the first VTR is transferred to the second VTR.
When playing back with TR, in order to eliminate the time lag between picture and sound, the relative positions of the video recording/playback head and the audio recording/playback head must match in the two VTRs.

If the above positional relationships do not match each other, the first VTR
When playing back a tape recorded on a second VTR, the picture and sound will be out of sync with each other in time, so if there is background music, etc., there will be no problem even if you watch the playback picture on a television receiver. Although this does not occur, the appearance of people speaking seems to be extremely out of sync, making it impossible to achieve so-called lip synchronization. Referring to FIG. 1, which shows a plan view of the main parts of a VTR, 1 is a magnetic head for recording and reproducing video signals (hereinafter referred to as a video head);
Attached to the tip of the head bar 2, the head cylinder 3
It is stored inside and can be rotated.

4 is a magnetic tape that is wound once around the outer circumferential surface of the head cylinder 3 and runs in the direction of arrow A, and the tape 4 is a magnetic tape that is wound once around the outer peripheral surface of the head cylinder 3 and runs in the direction of arrow A. It is held between a capstan 7 and a pinch roller 6 and runs at a constant speed.

Y is a portion where the video signal recording head 1 is in contact with the video width of the magnetic tape 4, and is a portion where one field of an image is recorded. In reality, it is difficult to wrap the magnetic tape 4 completely 3,600 times, and the portion where the magnetic tape 4 enters (or exits) is not recorded well. Therefore, the vertical synchronization signal in the video signal is recorded in this part. x is the distance from the end of the recorded portion of one field to the gap of the composite head 5. If this X value changes for each VTR, the timing of the reproduction signal of the video signal and the audio signal will be shifted.

In extreme cases, the movements of the lips and the voice heard may be out of sync. Also, this X value is the control pitch, n
A deviation other than the pitch (n=1, 2, 3, . . . ) causes a tracking deviation, and the best reproduced image cannot be seen at the position where tracking is fixed. Therefore, to adjust the position of the compound head, first play a recorded tape recorded on a VTR with the compound head in the correct position on the VTR to be adjusted, set the tracking shifter to a fixed state, and then play the tape. The position of the composite head was adjusted so that the output of the video signal reproducing amplifier was maximized.

This adjustment is based on the premise that the composite head will not deviate by more than the control pulse pitch recorded on the tape. For example, for a two-head VTR with a tape speed Vt of 190.5 rails/sec, such as a VTR compliant with the Electronic Machinery Industry Association standard, when recording an NTSC standard television signal, the vertical synchronization signal frequency nv is 59. ．． Since it is group mZ,
The control pulse pitch Pc is Pc=2Vt/5V, and Pc is approximately 6.36 ribs. However, the tape speed V
If the television signal described above is recorded on a rotating one-head VTR with t=8 mosquitoes/sec, Pc will be about 1.33. In the previous example of a two-head VTR, if you install a composite head at a position that is shifted by one pitch, you can clearly see the difference between the image and sound, but in the later one-head VTR, the difference between one pitch or several pitches is clearly visible. Even if it is adjusted to the correct position, it is difficult to visually understand.

For this reason, in the above-mentioned adjustment method in which a standard tape is played back on a VTR to be adjusted and the playback video output of the playback intensifier is maximized, the position of the compound head may be adjusted in a rotational manner. In this case, the X value will be different between the two VTRs, and the timing of the image and sound will deviate from each other. The present invention proposes a method that can easily and accurately adjust the position of a compound head even in a single-head rotation type NTR with a low tape speed.
In other words, the purpose is to propose a method to solve one problem of compatibility. An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the same parts as in FIG. 2 are given the same numbers and will be explained. In FIG. 2, a magnetic tape 4 is held by a capstan 7 and a pinch roller 6 and is made to run in the direction of arrow A. 2 is a head bar with the video head 1 attached to its tip; 8 is a magnet attached to the head bar 2; 39 is a magnetic head fixedly attached to the main body facing the magnet 8; and the magnetic head 39 constitute a rotational position/false detector for the head bar 2.

Reference numeral 11 denotes a motor for driving the head bar, and the motor shaft 10 and the head bar shaft 9 may be integrated, or the motor shaft and the head bar shaft may each be provided with pulleys and belted.

Reference numeral 12 denotes a control system for the head bar drive motor 1, which controls the detection signal from the rotational position detection magnetic head 39 and the vertical synchronization signal applied from the video signal input terminal 20 to have a constant relationship during recording. controlled.

The output from the rotational position/false detection magnetic head 39 is intensified by the pulse intensifier 13 and triggers the 1/5 frequency dividing circuit 14 . Next, recording and reproduction of video signals and audio signals in a normal case will be explained. In a normal case, the switch SW is connected to the N side.

During recording, switches SW2, SW3, SW4, and SW5 are all set to R.
connected to the side. The video signal applied to the video signal input terminal 201 is amplified by the input video signal intensifier 21,
The FM modulator 22 modulates the signal, and the modulated signal is sent to the recording intensifier 23. When the switch SW, is connected to the N side, the recording intensifier 23 uses the FM modulator 2.
The output signal of No. 2 is incremented as it is and is recorded on the magnetic tape 4 by the video head 1 via the SW 2 as diagonal tracks as shown in FIG. The audio signal is applied to the audio signal input terminal 34, multiplied by the input multiplier 37, the frequency characteristics of the recording side of the input signal are maintained by the equalizer 36, and the voltage is supplied to the recording multiplier 35. be done.

When the switch SW is on the N side, the signal input to the recording intensifier 35 is intensified as it is and output, combined with the output of the high frequency oscillator 38 for high frequency bias recording, and then sent via the switch SW5. , is recorded on the audio track by the composite head 5. During playback, switch SW2 and switch SW5 are connected to the P side.

As shown in FIG. 3, the video signal recorded on diagonal tracks on the magnetic tape 4 is reproduced by the video head 1 and supplied to the reproduction intensifier 29 via the switch SW2.
The output of the regenerative multiplier 29 is input to the limiter 28 , where it is limited, demodulated by the demodulator 27 , and then supplied to the synchronizing signal switching circuit 26 . In the synchronization signal exchange circuit 26, part of the demodulated signal (before and after the vertical synchronization signal) is exchanged with the signal from the pseudo synchronization signal generator 40. The output of the synchronizing signal switching circuit 26 is multiplied by the multiplier 25 and then output to the output terminal 24 . The audio signal is generated by reproducing the signal recorded on the audio track with the composite head 5 and passing it through the switch SW5 to the reproduction intensifier 30.
is applied to

The output of the regenerative multiplier 30 is compensated for the frequency characteristics on the reproducing side by an equalizer 31, and then supplied to a multiplier 32, and after being amplified, is applied to an output terminal 33. Next, the case of creating this standard tape will be explained. Switch SW, is connected to the X side. The output of the rotational position detection magnetic head 39 is
After being intensified by the pulse intensifier 13 and delayed in time by the mono multivibrator 41, 1/ear frequency dividing circuit 1 4
The frequency is divided into 1/8. As shown in FIG. 4, the delay time of the mono multi-viprator 13 is determined by the vertical synchronization signal VS and the rotational position detection signal RD in the head control system 12.
Since the rotation is controlled, the mono multivibrator 41
As shown in FIG. 4 MV, the output of is the time at which the vertical synchronizing signal VS arrives from the detection time of the position detection signal RD. 1/5
The output of the frequency dividing circuit 14 is supplied to a video signal recording intensifier 23 and an audio signal recording intensifier 35 via a switch SW.

In the video signal recording intensifier 23, when there is an input to the 1'5 frequency dividing circuit, a gate is applied to the output of the FM modulator 22, and the signal is recorded on the magnetic tape as a signal as shown in FIG. 4 RC. Similarly for the audio signal, the output of the equalizer 36 is gated by the output of the 1' ear frequency dividing circuit 14, and the output of the recording intensifier is as shown in FIG. 4 SC, which is synthesized with the high frequency bias signal. , is recorded on the audio track by the composite head 5 via the switch SW5.

Of course, if this is recorded, the x value in Figure 1 is adjusted accurately using a fixed length tape or the like.

The recorded standard tape created in this way is
When applied to TR, the signal of the video signal reproduction intensifier 29 is
It will look like Figure 4 PB.

The reason why there is sufficient output at both ends of one field of the signal PB is that there is insufficient contact between the video head 1 and the magnetic tape 4 at the beginning of the magnetic tape 4 touching the head cylinder and at the beginning of the output. This is because recording and playback cannot be performed sufficiently. Further, the reproduced signal of the audio signal, that is, the output of the reproducing intensifier 30 is as shown in FIG. 4 SP. Signal PB
, SP in this case, of course, will be like this even if the position of the composite head 5 is correct or if the self-alignment is performed. However, when the power of the composite head 5 is not in the normal position, the output PB of the video signal reproduction intensifier 29 and the output SD of the audio signal reproduction intensifier 30 become as shown in FIG.

When these two signals are observed with a two-phenomenon oscilloscope, the times at which the signals are missing are different, as shown in FIG. This can be adjusted by shifting the position of the composite head 5 so that the missing times of the signals PB and SP match. In this way, by using a recorded standard tape created using Honryoma, the mounting position of the composite head 5 can be easily adjusted. Next, control of the rotating video head will be explained.

During recording, switches SW3 and SW4 are connected to the R side. The signal input from the video signal input terminal 20 is amplified by the video intensifier 21 and then sent to the vertical synchronizing signal separation circuit 1.
The vertical synchronization signal is separated at 8, which triggers the mono multivibrator 19 on the one hand, and is applied to the head control system 12 via the switch SW3. The signal converted into a square wave by the mono multivibrator 19 is amplified by the recording intensifier 17, and then recorded on the control track by the compound head 5 via the switch SW4. The head control system 12 compares the phases of the output of the vertical synchronization signal separation circuit 18 and the output of the pulse intensifier 13, which is an intensified signal from the rotational phase detection head, and the two signals are determined as shown in FIG. , RD, and the position of the fixed magnetic head is adjusted so that a vertical synchronizing signal is generated when the magnetic head reaches the tape entrance. The phase comparison signal is increased, the increased signal is supplied to the motor 11, and the relationship between the vertical synchronization signal and the rotational position detection signal is controlled as described above.

Further, during reproduction, switches SW3 and SW4 are connected to the P side. The signal recorded on the control track during recording is
After being reproduced by the composite head 5, the signal is amplified by the control signal intensifier 16 via the switch SW4, and then supplied to the head control system 12 via the switch SW3. The head control system 12 compares the phase of the control signal with the output of the rotational position detector, increases the output signal of the phase comparator so that the video head 1 traces the recorded video track, and controls the motor. V is supplied to 1 and 1, and the tracking servo is performed. FIG. 3 is a pattern diagram of the adjustment tape according to the present invention.

55 is an audio track, 56 is a video track, 5
7 is a control track.

58 is an unrecorded portion of the video track, and 59 is an unrecorded portion of the audio signal.

W is the magnetic tape width, Vt is the tape speed, mev is the vertical synchronization signal frequency in the video signal, and control pitch P
c becomes Pc=Vt/〆v. In FIG. 4, VS is the output of the vertical synchronization signal separation circuit 18, and RD is the rotational position detection head 39.
PA is the output of the pulse intensifier 13, MU is the output of the mono multivibrator 41, DC is the output of the 1/ear division signal, RC is the output of the recording intensifier 23, and PB is the reproduction intensifier. The output of the amplifier 29, SC is the output of the audio signal recording intensifier 35, and S
P and SD are the outputs of the audio signal reproducing intensifier 30. Fifth
The figure shows another embodiment of the present invention, in which a gate circuit 15 is added and a part of the track is left unrecorded instead of leaving one field unrecorded.

To explain only the difference from FIG. 2, the delay amount of the mono multivibrator 41 is later than the timing when the vertical synchronization signal comes, and the signal VS and MM in FIG.
The relationship will be like this. The output of the mono multivibrator 41 triggers the 1/frequency divider circuit 14. Gate reward 15
Now, a signal as shown in FIG. 7 DM is created using the output of the 1/8 frequency divider circuit 14 and the output of the monomulti-by-player 41. The output of this gate circuit 15 gates the video signal and the audio signal to create a standard tape. FIG. 6 is a pattern diagram of this embodiment, and as is clear from the diagram, only a portion of one video track is unrecorded. FIG. 7 is a time relationship diagram between the video signal and the audio signal in the second embodiment, where VS is the output of the vertical synchronizing signal circuit 18, RO is the output of the pulse detector 39, and PA is the pulse intensifier 13. , MM is the output of the mono multivibrator 41, DC' is the output of the 1/5 frequency divider circuit 14, and D
M is the output of the gate circuit 15, RC' is the recording intensifier 23
PB' is the output of the reproducing intensifier 29, SC' is the output of the audio signal recording intensifier 35, and SP' and SD' are the outputs of the audio signal reproducing intensifier 30.

As explained above, the position adjustment of the composite head can be performed by using the magnetic tape recorded with the device and the device according to the present invention.
This can be easily carried out with just a two-phenomenon oscilloscope, without adding any particular circuit or adjustment mechanism to the VTR to be adjusted, and the work efficiency of the production line can be improved.

Furthermore, if the linearity of the tape pattern of this apparatus for creating the adjustment tape is accurately adjusted, it is possible to sufficiently adjust the VTR even if the video track is slightly missing. In this manner, the control pulse pitch is 4.0 mm, and the head position adjustment in a VTR can be easily and accurately set.

[Brief explanation of the drawing]

FIG. 1 is a plan view of essential parts of a VTR, FIG. 2 is a block diagram of a standard tape recording VTR used in the adjustment method for a magnetic green screen playback device in an embodiment of the present invention, and FIG. 3 is a magnetic tape recording VTR. A diagram showing the recording pattern above, Figure 4 is the VT of Figure 2.
5 is a block diagram of a VTR in another embodiment, FIG. 6 is a diagram showing a recording pattern on a magnetic tape, and FIG. 7 is a waveform diagram explaining the operation of each part of the VTR shown in FIG. 5. FIG. 1... Magnetic head for recording and reproducing video signals, 4...
Magnetic tape, 5... Composite head. Fig. 1 Fig. 7 Fig. N Rudder diagram of ship chart

Claims (1)

[Claims] 1. Recording of a video signal is stopped for a fixed period of time every few fields using a signal obtained from a vertical synchronization pulse, and a standard tape is recorded by intermittent audio signals in synchronization with the intermittent intermittent of the video signal. The standard tape is produced by a playback device, the standard tape is played back by a second magnetic recording and playback device to be adjusted, and the control head and audio head for the magnetic head for video signal recording and playback of the second magnetic recording and playback device are integrated. 1. A method for adjusting a magnetic recording and reproducing device, which comprises correctly adjusting the relative position of a compound head that has been converted into a magnetic head.