JPS58175378A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To ensure the tracking control during a slow reproduction, by recording and reproducing through video tracks (m) types (m>=3) of pilot signals having different frequencies, phases or time and space dispositions. CONSTITUTION:Four type of pilot signals f1-f4 of different frequencies are prepared. These pilot signals are added to the video signal on a magnetic tape 1, and tracks A1 and A2 are recorded by the 1st head. At the same time, tracks B1 and B2 are recorded by the 2nd head. The pilot signals of f1, f2, f3 and f4 are successively recorded on tracks A1, B1, A2 and B2 respectively. In a slow reproduction mode, the pilot signal of the scanning track and pilot signals of tracks adjacent to said scanning track are obtained. Then the levels of these pilot signals are detected to obtain an accurate tracking error signal which contains the tracking shift and its extent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing apparatus equipped with a device for fixing the position of a noise par appearing on a screen during slow motion scene reproduction.

In a magnetic recording and reproducing device that records and reproduces video signals by diagonally scanning a magnetic tape with a rotating video head, the magnetic tape is run at a slower speed than during recording in order to slow down the movement of the reproduced image and view it. A slow-mo scene playback time structure is used.

During slow playback, the video head scans across several video tracks.

A horizontally striped portion with a low sys ratio, that is, a noise par, appears on the reproduction surface. This noise bar will flow over one screen unless the ratio of the reproduction speed and recording speed of the magnetic tape is constant, making it very difficult to see and visually undesirable.

Therefore, in order to fix the position where this noise bar occurs, in conventional magnetic recording and reproducing devices, during slow playback, a tracking control control is recorded on the condominium hook at the bottom edge of the magnetic tape in relation to the recording position of the video track. The tape running phase is controlled using the signal.

Attempts have been made to make the magnetic tape always run at a constant speed. This control signal is a signal that is recorded by the control head in the longitudinal direction of the magnetic tape at a frequency that is half the vertical synchronization signal of the recorded Eirin signal, and is recorded on the tape at intervals corresponding to the tape speed at the time of recording. Ru. Therefore, by controlling the tape running so that the frequency of this reproduction control signal becomes constant during slow reproduction, the position where the noise bar occurs can be easily fixed.

However, in the tracking control method using this control signal, the video head and the control head are located far apart.

Since the tracking is deviated due to the driving of the tape length during that time, it becomes necessary for the user to adjust the tracking by looking at the reproduced image, and a tracking adjustment mechanism is essential.

Another drawback is that tracking errors can only be detected intermittently, making it impossible to obtain sufficient tracking control performance, especially when the pitch of the video track becomes narrower due to longer recording times.

Therefore, tracking errors can always be detected,
An automatic tracking zero control system has been devised that eliminates the need for a tracking adjustment mechanism.

A typical example is a method in which a pilot signal, which serves as tracking information during playback, is superimposed on the video signal and recorded on a video track of a magnetic tape using a rotating video head. When this pilot signal is regenerated to form a tracking error signal and tracking control is performed, automation of tracking control is achieved and its control performance is also improved.

However, on the other hand, this pilot method is different from the method using control signals described above.

There are no control signals recorded at equal intervals in the running direction of the tape, that is, in its longitudinal direction, in a predetermined phase relationship with the video track, nor a control head for recording and reproducing these signals.

Therefore, during slow playback, the conventional method of fixing the noise bar position f11 using a control signal cannot be applied, and it is necessary to devise a new method.

The purpose of the present invention is to solve the above problems by using a pilot signal recorded on a video track.

It is an object of the present invention to provide a means for fixing the generation position of a noise bar during slow playback in a magnetic recording and reproducing apparatus that performs tracking control.

In order to achieve the above purpose, the unexploded @FJ, shoulder types with different frequencies, phases, or temporal-spatial arrangements (
WaS integer) pilot signals are alternately recorded for each video track, the pilot signals are detected during playback to generate a tracking error signal, and tracking control is performed using this signal. The tracking error signal is sampled and held at a predetermined time point when the controller scans a predetermined point on the magnetic tape, and the sampled and held tracking error signal is supplied to the magnetic tape drive device, thereby suppressing the noise bar that appears during playback. It is configured to fix the generation position.

The present invention will be explained in detail below using the drawings.

FIG. 1 is a block diagram showing a configuration example of a rotating head helical scan type magnetic recording/reproducing apparatus according to the present invention, and FIG.
The figure is a tape pattern diagram showing a row of video tracks on a magnetic tape multiplexed on a pilot signal.
FIG. 3 is a circuit block diagram showing an embodiment of the tracking error detection device according to the present invention.

In FIG. 1, a magnetic tape 1 is driven by a capstan 2 and runs in the direction of the solid arrow. This capstan 2 is rotationally driven by a capstan motor 3. On the other hand, two video heads 5 and 6 mounted on the disk 4 at a distance of 180 degrees from each other are driven by a disk motor 7 and rotate in the direction of the dashed arrow. This disk 4 is attached to a rotating shaft inclined with respect to the longitudinal direction of the tape 1.
It is rotated at a frequency of .

Further, the tape IFi is wrapped around the disk 4 approximately in half a circle.

Therefore, the video head 5.6 ri alternately scans the tape 1 in diagonal directions from bottom to top.

The video signal is returned to each video track in units of one field of the sandwiched signal.

The video frames 5 and 6 have different azimuth angles, so that high-density recording can be performed without providing a guard band, as shown in FIG. 142.

First, during recording, the Eirin signal applied to the terminal 8 and the pilot signal generated by the pilot signal generation circuit 9 are added by the adder S unit 10, and then amplified by the recording amplifier 11. The signal is supplied to video heads 5 and 6 via the tape 1 and recorded on a video track on the tape 1.

FIG. 2 shows an example of a video track pattern when four types of pilot signals having different frequencies are used as the pilot number 45. In Figure 2, A1
and A2 are video tracks recorded by the video head 5, and Bs and Bz are video tracks recorded by the video head 6. Furthermore, C to f4 indicate the frequencies of the pilot signals recorded on the respective video docks.

In this way, four-frequency pilot signals are alternately recorded for each video track. The frequencies of these pilot signals are selected to be lower than the frequency band of the optical signals and are so low that they are not affected by the azimuth angle of the video head 5.6. Therefore, during playback, when the video head 5.6 is moved over a recorded video track, it detects not only the pilot signal of the video track that is being correctly scanned, but also the pilot signals from the video tracks adjacent to it on both sides. be able to. Therefore, by detecting the reproduction levels of the pilot signals from both adjacent tracks, it is possible to obtain an accurate tracking error signal that includes the direction and magnitude of the tracking error, as will be described later.

Next, the operation during playback will be explained. In FIG. 1, the video head 5 and 60 rotation phases are detected by the tack head 16,
This detection signal is sent to the phase A11 circuit 14, and its output is the head phase detection signal y and the reference signal RE of the quadruplets 15.
The video head 5.6 is driven by the reference signal RE
The video head is rotated at a constant phase and speed determined by F. If the frequency of this reference signal REF is selected to be approximately equal to 1/2 the frequency of the vertical synchronization signal of the recording video signal, the rotation speed of the video head 5 and 60 will be It will be almost the same as when recording.

With the video head 5.6 rotating at a predetermined speed, the running of the tape 10 is controlled by the tracking error signal, so that the video head 5.6 accurately scans the desired recording video track. to perform tracking control. Next, this tracking control operation will be described.

First, the rotational speed of the capstan 2 is detected by the speed detector 18, this detection signal is sent to the frequency discriminator 19 to convert the speed control voltage spK according to the rotational speed, and this voltage SP is added to the adder 21. By supplying power to the capstan motor 5 through the motor drive circuit 22, speed control is performed so that the capstan 2 rotates at a predetermined speed. In addition, 20
is a quick station decision circuit.

On the other hand, the signals reproduced from the tape 1 by the video heads 5 and 6 are sent to the preamplifier 2 via the rotary transformer 12.
5 and is amplified. This amplified reproduction signal U is further sent to a video signal reproduction circuit 24, and when it becomes a desired reproduction video signal, it is sent to a tracking error detection circuit 26 via a low-pass filter 25.

The high-frequency video signal is removed from the reproduced signal by the low-pass filter 25, and only the pilot signal PL is separated and extracted. From this pilot signal PL, a tracking error signal TR is formed by the tracking error detection circuit 26 by the method described in FIG. S below. This tracking difference signal fR is sent to the adder 2 via a switch 29.
Send to 1.

By adding it to the speed control voltage SP and supplying it to the capstan motor 5 via the motor drive circuit 224, the rotation of the capstan 20 is controlled. As a result, the running phase of the tape 1 changes to 1111 in accordance with the tracking error signal rR.
#, and tracking control is performed so that the video head 5.6 correctly scans the video track.

Next, an example of forming the tracking error signal rR from the reproduced pilot signal PL will be described with reference to FIG.

Now, the frequency of the 4J4 wave pilot signal shown in Fig. 2 is 71-10.5f1. fl-9, s7' wing h-6
,5fu, f4-7,5fH (here, fmtd
frequency of the horizontal synchronizing signal of the pinned image signal), then video track A1. In the case of At Y scanning, if the tracking shifts to the right, the r-f! +-1 bar f* I-fi
If the l component increases and shifts to the left, 1 bar f'l-171
-fzl=sfH component is increased. Also video track B1
．． In the case of Bsyl scanning, if the tracking shifts to the right, the 1H component increases, and if the tracking shifts to the left.

Gettle l-114-fsl-fil component increases. Therefore, in FIG. 3, a local pilot signal F having the same frequency as the pilot signal recorded on the main video track to be scanned is generated by the pilot signal generation circuit 9 during playback, and this local pilot signal F and the playback The pilot signal PL is sent to a mixer circuit 50 consisting of, for example, a double-balanced modulator, and its output is a signal having a frequency that is the difference between the frequencies of the two signals, ie, the fH described above.
A composite signal of the acid component and 5fH component is obtained. Next, from this composite signal, a bandpass filter 51. ! 52, the fH acid component 3fH component is separated, and the envelope detection circuit 55. When obtained, the differential voltage signals T and T of the fH acid component and the 5fys component are obtained as the differential output. The differential voltage signals T and T1 represent the level difference between pilot signals detected from adjacent tracks on both sides of the main track to be scanned.

At this time, when the main track is AI straddle As and when BIt
In the case of 1 iBz, as described above, the direction of increase/decrease of the difference frequency signal with respect to the direction of tracking deviation is reversed. Therefore, the differential amplifier 55 generates two differential voltage signals h(Ps-Pl)-r with different polarities.

kcP2-PI)-r, (A: number of feet) t/output, and 77) The differential outputs r and T are respectively supplied to the gate circuits 56 and 57. Then, a gate signal GT is generated from the head phase detection signal y by a gate signal forming circuit 59.
and.

Using the signal α with the opposite polarity in the inverter circuit 5B, the gate circuits 36 and 57 are connected to the respective gate signals GT.
, GT, the differential voltage signals having different polarities for each track are connected to obtain a continuous correct tracking error No. 48 TR.

In FIG. 5, the gate signal forming circuit 59 outputs - as its output signal Gr during normal playback as described above.
・Grot phase detection・) O, 5F, also 1//&
During double-speed slow playback (an integer of 2), it is configured to output a signal obtained by frequency-dividing the head phase detection signal by 1/rL.

Next, we will explain #Ki when playing in slow motion. First, in FIG. 1, the running speed of the tape 1 is set by the speed setting circuit 20.
The rotational speed of the capstan 20 is set so as to be closer to a predetermined speed than during recording, and the switch 29 is turned to the appropriate 2 side. - The gate signal Gr, which is the output of the gate signal forming circuit 59, is sent to the pulse generating circuit 27.
At a predetermined time point of the signal GT, a pulling pulse S is generated, and this pulse 57 sample-hold circuit 2B! Send τ. The tracking error signal IR which is the output of the tracking error detection circuit 26 is added to the sample hold circuit 2B, and this tracking error signal q
rR is sampled and held by a sampling pulse S, and a tracking error signal rH at a predetermined time point is output.

This sampled and held tracking error signal fB
, switch 29, adder 21 . By applying it to the capstan motor S via the MoI drive circuit 22, the rotation of the capstuff 20 is controlled, and the running phase of the tape 10 is controlled so that the generation position of the noise bar is fixed during slow playback.

Next, a method for fixing the generation position of a noise bar during slow playback will be described for the case where 1/2 slow playback is performed in the same direction as normal playback.

Figure 4 (1) l (3), (4+ is the 1st video track on tape 1 (indicated by a solid line) and the video when tape 1 is run at 1/2 speed in the same direction as normal playback. It shows the scanning trajectories (indicated by broken lines) of the heads 5 and 6. Also, FIG. 4 shows the envelope of the video signal reproduced during 21Fi, 1/2 slot one reproduction.

During this 1/2 slot playback, as is well known, the position of the noise bar is forced into the vertical blanking period of the TV Gene receiver.

It is possible to prevent the noise bar from appearing on the playback screen. Figure 4 represents the scanning phases of the video heads 5 and 6 during such noiseless slow playback. ) These video heads 5.6 cannot reproduce signals from tape 1 even if they scan tracks recorded at azimuth angles different from their respective azimuth angles. is #I4
When scanning is performed as shown in FIG. 4 (1), the reproduction envelope of the Eirin signal increases and decreases as shown in FIG. 4 (2).

In the part indicated by a circle in the figure, the Sβ ratio is small because the amplitude of the reproduction envelope is small, resulting in an imitation noise bar during the first reproduction. However, in the running phase state as shown in FIG.
Since this is the part where the reproduction signal of No. 6 switches, that is, near the vertical synchronization signal of the reproduction signal, no noise bar will appear on the 91 screen within the vertical blanking period of the TV Gene receiver.

Next, FIG. 4 (5) l (4) Fi shows the scanning phases of the video heads 5 and 6 at different times. JIffl (desired noiseless 1/2
FIG. 6 is a diagram illustrating both a scanning phase state that results in double-speed slow playback and a scanning phase state that deviates from this desired state. In addition, in FIGS. 1(1), (5) and (4), the same locations of the scanning center points of the heads 5 and 6 are indicated by the same alphabetical symbols.

First, Fig. 4 (5) shows that the video head 5 correctly scans the track A1 at the start of scanning (the scanning center of the head 50 at this time is point A in the figure), so that noiseless slow playback is achieved. When head 6 is scanning correctly between tracks At and BI (the center of scanning of head 60 at this time is point B in the figure) (indicated by a broken line), head 5 deviates from the noiseless condition and scans track Ih. Scanning starts (the center of scanning of the head 60 at this time is point A' in the figure), and the hector 6 starts scanning between tracks B1 and A! (the center of scanning of the head 60 at this time is point B' in the figure). (shown as a solid line).

Also, Figure 4 (4) shows the video head 5 at a different point in time than Figure 4 (5). This shows the scanning position of B. At the start of scanning, the head 5 correctly scans the track exit to achieve noiseless slow playback (the center of scanning of the head 50 at this time is point A" in the figure). ) and head 6
are tracks lh and a! If the head 60 is scanning correctly between tracks B1 and A2 (at this time, the scanning center of the head 60 is at point B' in the figure) (shown by a broken line), the head 5 will start scanning between tracks B1 and A2, deviating from the noiseless condition. (The scan center of the head 50 at this time is point A in the figure), and the head 6 starts scanning between tracks Ih and As (the head 60 at this time
The scanning center is point B in the figure (shown as a solid line).

Next, in FIG. 5, the video heads 5 and 6 are shown in FIG.
) t (4) is a timing chart showing signal waveforms of various parts when in the scanning phase state shown in (4).

In FIG. 5, (1) is the tracking difference signal rR1 during 1/2 speed slow playback and the signal 1B obtained by sampling and holding this error signal rR, (2) the Fi gate signal G
The sampling pulse S, (5
) is a gate signal forming circuit 59 from the head phase detection signal y.
The gate signal GT generated in (4) is the local pilot signal F applied to the generation escape mixer circuit 30 by the pilot signal generation circuit 9, and (s) is the head phase detection signal y.

The high level (b) period of the head phase detection signal y is the period when the video head 5 is scanning the tape 1, and the low level (the gradient period is the period when the video head 6 is scanning the tape 1). The time when the signal y switches from B to L and the time when it switches from L to H correspond to the time when the video radars 5 and 6 start scanning the tape 1, respectively. The time when the gate signal Gr, which is a signal obtained by dividing the signal y by half, switches from II to L and from L to B corresponds to the time when the video head 5 starts scanning the tape 1. Every time the level of this signal GT changes, immediately after the switching point 9, a sampling pulse S shown in FIG. 5(2)K is formed, and this pulse S causes As shown, the tracking error signal TR is sampled and held to produce an error signal TB'4t4 indicated point by point.

In FIG. 5(1), the horizontal axis indicates the time axis, and the vertical axis indicates the voltage values of the tracking error signals rR and rH. Note that the tracking error occurs when the TR video heads 5 and 6 shown by solid lines scan the video track in a phase state that provides noiseless 1/2 slow playback as shown in FIG. 4 (1) at the start of scanning. This is the waveform of the signal. (s5 diagram (rim, VmV" + Fs & ) '/' 1
jlE 4 Figure (3) r t4) If the head 5, which should scan points A and A# at the start of scanning, shifts to the right and scans points A' and A, respectively, then For example, the voltage of the tracking error signal TR drops as shown by r^' and F/A# in FIG. 5(1).

On the other hand, if it is shifted to the left, Ki! , the voltage of the error signal TH increases. On the other hand, when the head 5 starts scanning, point A in Figure 4 (1* (3) l (4),
If the points are scanned correctly, the fH acid component signals P1 and 5
When the amplitudes of the fm component signals Pl become equal, the voltage of the tracking error signal rR, which is the difference signal, is as shown in FIG.
rm, #'A' each equal to the average value as in 1)
becomes.

Now, the local pilot signal F is 6 in period C,
At the point when the video head 5 starts scanning the tape 1, #! 4. Scan point A in figure 4, shift the original position to the right, and
′ point is scanned.

In other words, when the running speed of tape 1 is fast, KFi, the pilot signal of frequency f4 is almost not detected.
-f t l-5fH component signal P1 is smaller than others,
On the other hand, the detection level of the pilot signal of frequency 12 is the maximum, and the signal PM of the component *-f 11-fm is dominant, and the difference signal is the tracking error signal TR.
1 pressure becomes low as shown by Vh' in FIG. 5(1). Therefore, at this point, the tracking error signal TH sampled and held by the sampling pulse SK shown in FIG. 5(2) also becomes low. Therefore, in the adder 21 of FIG. 1, the control voltage pH, which is the sum of the speed control voltage SP and the tracking error signal TB, is also low, and the motor drive power of the drive circuit 22 is reduced, so that the capstan motor 50 The number of rotations decreases, and the running speed of the tape 10 decreases.

Conversely, if the tracking is off to the left, that is, if the tape running speed is slow, the 5fyx component signal p
g increases, and the voltage of the tracking error signal TH increases. Therefore, the control voltage PE applied to the drive circuit 22 increases, the rotation of the capstan motor S becomes faster, and the tape running speed becomes faster.

By controlling in this manner, the tape running speed is kept constant, and at the time when the video head 5 starts scanning the tape 1.

It is possible to accurately track and scan the recording track, and as a result, it is possible to fix the position where the noise bar occurs during 1/2 speed slow playback in the same direction as the normal playback direction. Also, since it is possible to drive the generation position of the noise bar to the vertical female line elimination period as shown in FIG. 4 (2), noiseless t/zffl! Slow playback becomes OJ rudder.

Above, we have explained 1/2 speed slow playback in the same direction as during normal playback, but if the frequency division ratio of the gate signal Or obtained by dividing the head phase detection signal SF is 1/n
Even during slow playback at double speed (an integer of 2), the position of the noise bar can be fixed. Particularly, during 115x slow playback, it is possible to achieve noiseless reproduction in the same manner as in the above-mentioned 1/2x slow playback.

Also, when executing 1/n times faster throw in the opposite direction to normal endogeneity, gate signal GT, local pilot signal F
The present invention is applicable as long as the values are changed appropriately.

Further, in the above embodiment, a case has been described in which the video heads 5 and 6 are controlled to accurately scan the recording track at the time when they start scanning.

The present invention is also effective in controlling the recording track to be scanned correctly at any time after the start of scanning. Furthermore, the local pilot signal F and gate signal GT can also be changed as appropriate from the settings in the above-mentioned implementation column.

Furthermore, in the above embodiment, a method was described in which pilot signals of four frequencies are alternately recorded for each video track, but in the case of a method using a pilot signal of a frequency of class 34, class d5, class p or higher, Or, in the case of a method in which a pilot signal of a constant frequency is recorded with the phase changed for each video track, instead of recording pilot No. 111 continuously on the video recorder, for example, the horizontal SA of a TV Gene receiver is used. The present invention can also be applied to a method in which the phase and recording timing of a one-frequency signal are intermittently varied only during a predetermined period within a period, and the temporal and spatial arrangement is changed for each video track. be.

As described above, according to the present invention, by reproducing a pilot signal that makes true the frequency, phase, or temporal and spatial arrangement of m41Rc~3 (an integer of 3) recorded on a video track, continuous and accurate Since a tracking difference signal is obtained, sufficient automatic tracking control is achieved even during long-time recording, and the magnetic tape is By controlling the traveling phase, the position of the noise bar during slow playback can be adjusted.
is fixed, making the playback screen much easier to read.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a configuration example of a magnetic recording/reproducing apparatus according to the present invention, and FIG. 2 is a tape pattern diagram showing video tracks on a magnetic tape. Figure S is a block diagram showing one embodiment of the present invention, Figure a4 (
1) l (5) and (4) are tape pattern diagrams showing the video tracks on the magnetic tape, the scanning locus of the video head during 1/2 speed slow playback, and Figure 4 (2) is the envelope of the reproduced video signal. FIG. 5 is a signal waveform diagram for explaining the present invention in detail. 1...Magnetic tape, 2...Capstan. 5.6...Video head. 9...Pilot signal generation circuit. 26...Tracking error detection circuit. 27...Pulse generation circuit. 28-・Sample and hold circuit. 59...Gate signal formation circuit. Representative Patent Attorney Susuki 1) Ri2he 171, 4th District rt) 8 B 8' B
8 8Z8 “′

Claims (1)

[Claims] A rotating video head that scans the magnetic tape diagonally, and
A circuit that generates il (integer nL≧5) signals and the video head superimpose the m types of signals on video signals for each video track on the magnetic tape. a device for reproducing the signal from the magnetic tape by the video head; and a device for generating a signal corresponding to a tracking error of the video head from the signal. In a magnetic recording and reproducing apparatus comprising a tracking error detection circuit and a device that performs tracking control so that the video head correctly scans the video track based on the tracking error signal, during reproduction, the recording speed is higher than during recording on the magnetic tape. A device that runs at a low speed and a circuit that samples and holds the tracking error signal at a predetermined time point when the video head scans a predetermined point on the magnetic tape during the low-speed playback are provided. A signal is supplied to the low speed drive of the magnetic tape, and the playback i6
A magnetic recording/reproducing device characterized in that the position of occurrence of noise particles appearing in the recording is fixed.