JPS5992460A - Magnetic recording and reproducing system - Google Patents

Abstract

PURPOSE:To perform good tracking control by recording, in a record mode, the pilot signals different in frequency at the position corresponding approximately to the tracks at both ends holding one track between in the form of a signal which can be discriminated from the record signal of an intermediate track, and detecting said pilot signals in a reproduction mode, and using a difference signal between both detected levels. CONSTITUTION:Pilot signals P1 and P2 of frequencies f1 and f2 are recorded respectively on record tracks T1, T2- with a positional relation where the positions of tracks are approximately coincident with each other every other track and no coincidence is obtained between adjacent tracks. The video signal reproduction is switched to a rotary head, and a record track T3 is scanned. When the head reaches an area corresponding to S2, the setting time is up with the 2nd time constant circuit 30. Then the output of the circuit 30 falls, and the 1st and 2nd sample holding circuits 31 and 32 work to hold the levels corresponding to the signals P1 and P2, respectively. Then a tracking error signal is outputted from a differential amplifier 33 and corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic recording and reproducing apparatus that employs a method in which a large number of recording tracks are arranged in parallel, such as a rotating magnetic head type VTR (video recorder). In particular, the present invention relates to a magnetic recording/reproduction method that performs tracking control without using a control signal during reproduction.

[Technical background of the invention]

The conventional tracking control method using control signals in this type of magnetic recording/reproducing device, for example, a VTR, is the first method.
As shown in the figure.

FIG. 1 shows a block diagram of a capstan motor using a DC (direct current) motor as a cylinder motor and a capstan motor.

In FIG. 1, a magnetic tube 1 is wound obliquely over approximately 180° on a rotating cylinder (not shown) and is transported by a capstan 2 and pinch rollers 3. The rotating cylinder has built-in magnetic heads (video heads) 5 and 6 fixed on a rotating disk 4, and is rotationally driven by a cylinder motor 7. The cylinder motor 7 is driven and controlled by a speed control circuit 8 and a phase control circuit 9. The speed control circuit 8 has a cycle of an AC signal obtained from a frequency generator (not shown) directly connected to the rotating shaft of the cylinder motor 7, and another signal delayed by a certain period of time.
The cylinder motor 7 is configured to obtain a speed error signal by comparing the delay times of two reference signals, and the cylinder motor 7 rotates at a substantially constant rotation speed based on the speed error signal. A magnet (not shown) is attached to the rotating disk 4, and a detection head 10 fixed to the fixed side rotates the cylinder twice for each rotation of the rotating disk 4. A? A stray signal is detected. During recording, the phase control circuit 9 determines the phase of the vertical synchronization signal that is input multiple times through the terminal 11 and the signal obtained from the detection head 10 twice per rotation.
By inputting the resulting phase error signal to the speed control circuit 8, the rotational phase of the rotary cylinder is synchronized with the phase of the vertical synchronization signal. In addition, SW1
~SW3 is a changeover switch for recording and reproducing modes, and the R terminal side is selectively connected during recording, and the P terminal side is selectively connected during reproducing. Similarly to the control of the cylinder motor 7, the rotational speed of the capstan motor 12- is controlled by the speed control circuit 13 and the phase control circuit 14. Rotational force is transmitted to the capstan 2 via a belt 15 from a capstan motor 12 . During recording, a signal is generated once per rotation of the capstan motor 1201 detected by the detection head 16 and the terminal 17
The phase control circuit 14 compares the phase of the input signal with the output signal from a reference oscillator (not shown) to control the rotational phase of the capstan motor 12. On the other hand, a signal synchronized with the rotation of the rotary cylinder given from the detection head 10 during recording is frequency-divided by the 7-lip flop 18 and recorded on the magnetic tape as a control signal by the control head 19tlCyo9.

During reproduction, the switches SW1 to SW8W3 are connected to the P terminal side, the phase control of the cylinder motor 7 is performed by the output of the detection head 10 and the output of the reference oscillator given from the terminal 17, and the capstan motor 12 is controlled by the output of the detection head 16. Phase control is applied between the output and the control signal that is played back by the control head 19.

In this way, in conventional VTRs, a control signal is recorded in synchronization with the rotation of a rotary cylinder during recording, and during playback, the tape transport speed by the capstan motor 12 is varied according to the output phase of the control signal. The magnetic heads 5 and 6 are configured to correctly track on the recording tracks.Therefore, it is necessary to specially provide a control track for tracking control on the recording surface of the magnetic head. in this case,
The distance between the rotating magnetic heads 5, 6 and the control head 19 varies depending on the system, but is usually about 80 mm, for example, 3 times that of a consumer A-inch cassette VTR. In this mode, the tape feed speed is about 11i, and in the NTSC system, 60 tracks are recorded per second.

Therefore, it corresponds to the rotating magnetic heads 5 and 6.

Since the control signals are recorded approximately 40 mm away on the magnetic chip, even if there is actual track misalignment on the rotating magnetic head 5.6, it must be known with certainty. (Rotating magnetic head 5, 6
Even if there is a track deviation, it cannot be detected unless there is a deviation at the control head 19. Oh my,
Any deviation between the rotating magnetic healds 5, 6 and the control track cannot be detected. ), tracking control is a kind of predictive control. For this reason, tracking errors and playback signal deterioration are likely to occur due to tape expansion and contraction due to changes in tape tension, uneven rotation of the capstan motor 12, etc., and extremely high-precision chip/joist control and motor speed control are likely to occur. was needed.

[Purpose of the invention]

An object of the present invention is to provide a magnetic recording and reproducing system that can perform good tracking control without providing a control track and also realize effective use of the recording surface of a recording medium.

[Summary of the invention]

In the present invention, during recording, pilot signals of different frequencies are recorded on substantially corresponding positions of tracks on both sides of the L track in a form that can be distinguished from the recording signal of the intermediate track, so that each recording track is - A mother pilot signal is recorded, and during playback, pilot signals of the above-mentioned frequencies are detected from tracks on both sides of the reproduced track, and the difference signal between the detection levels of the two is used as a tracking error signal to perform tracking control. It is characterized by

[Embodiments of the invention]

FIG. 2 shows the recording and tracking of tracking information in an embodiment in which the present invention is applied to a rotating magnetic head type VTR, and FIG. 3 shows the configuration of a tracking error detection circuit in the same embodiment. FIG. 4 shows the operation timing in the same embodiment. First, FIG. 2 will be explained in detail. In Figure 2, N
'r11'r21... are information recording tracks formed along the moving direction T of the rotating magnetic head. However, for convenience of explanation, it is shown here as a direction perpendicular to the movement direction.

These recording tracks T1+T2+... are arranged in the tape moving direction R. In this embodiment, as shown in the figure, these recording tracks TI+T2+... The first and second frequencies fl and f2 are arranged in a so-called staggered positional relationship, respectively.
Record the mother pilot signals P1 and P2.

These first and second pilot signals Pl and P2
is every other track, 9 points 2. For example, as shown in the figure, P1, P1, etc. are sequentially applied to each recording track T1+T2+... so that the recording positions in the / direction are almost the same and the pilot signals are not the same (frequency) between the closest tracks.
P□, P2.

The selection is made as follows: p2+ PI r PHt P2 *... Also, each /J? Irosoto signal pl
, p2 on the track are set approximately equal,
The recording position is, for example, as shown in the figure, on one edge side of the magnetic tape 1, at the common starting end of each recording track 'rl l'r21..., preferably at a vertical retrace line part where there is little risk of directly affecting the video signal. etc. These pilot signals p1 and p2 are recorded in a separable manner superimposed on the video signal. Normally, it is sufficient to select frequencies f1° f2 of each pilot signal P1+P2 to be sufficiently different from those of the video signal, and simply superimpose them. Further, the frequency and two levels of the respective .eot signals P1+P2 are set so as to exert, for example, the same degree of leakage effect on the rotary magnetic heads 5 and 6 tracking adjacent tracks.

Such first and second pilot signals Pl.

P2 can be performed at the same time as video signal recording by superimposing signals in advance, and can be performed in the same manner as conventional video signal recording.

Next, the tracking device 2 used during playback as shown in FIG.
The configuration of the detection circuit will be explained.

In FIG. 3, reference numeral 20 denotes the A'lot signal P1. This is an input terminal for a video signal including the superimposition of P2 and the leakage effect from an adjacent track. The output is switched and selected. 21 is a first band/base filter (hereinafter referred to as BPF J of 111) for extracting a frequency component fl corresponding to the first pilot signal Pl from the reproduced video signal; 22;
Similarly, the second i? A second band filter (
Hereinafter [referred to as the second BPF J], 23 is synchronized with the rotation of the rotating cylinder and each recording track TI, T2.

A cylinder/gurus consisting of two noculus per rotation of the rotating cylinder corresponding to the starting end position of... (output of the detection head 10 shown in FIG.
is a cylinder/9 pulse input terminal that is given. 24 corresponds to the flip-flop 18 shown in FIG. a first flip-flop circuit (hereinafter referred to as "first FFJ") whose output is inverted every time a pulse is input;
25 is a second flip-flop circuit (hereinafter referred to as "second FF") whose output is inverted every time the Q output of the first FF 24 rises.
26 is a switcher that alternately switches the outputs of the first and second BPFs 21 and 22 to two signal paths every time the output of the second FF 25 is inverted.
7. The first switch 28 is configured using, for example, a diode, and detects the two outputs of the switcher 26 (AM detection). The second wave detector 29 is made of, for example, a monostable multi-gulator, etc. It rises in response to the rise of the Q output of the first FF 24 and corresponds to position 81 in Fig. 2 after a set time. The first time constant circuit 30 generates an output that falls at the time when the first FF consists of, for example, a monostable multivibrator. 2, which generates an output that rises in response to the rise of the 100 output and the fall of the Q output (also may be the fall of the Q output), and then falls after a set time at a time approximately corresponding to position 82 in Fig. 2. The time constant circuits 31 and 32 are the first time constant circuits. First and second sandal hold circuits sample and hold the outputs of the first and second detectors 27 and 28, respectively, in response to the fall of the output of the second time constant circuit 29, 30; and a differential amplifier that takes the difference between the hold outputs of the second Sanzor hold circuits 31 and 320;
34 is an output terminal for outputting a tracking error signal obtained as the output of the differential amplifier 33.

FIG. 4 shows the cylinder number J? input to the cylinder pulse input terminal 23. The waveforms of the Q output of the first FF 24, the output of the first time constant circuit 29, the output of the second time constant circuit 30, and the Q output of the second FF 25 are shown.

Next, the operation of this embodiment will be explained.

During recording, each recording track T11T21 shown in FIG.
As shown in the figure, the frequencies f0 and f are placed at the starting end position of
The first and second no'? As already mentioned, the pilot signals P□ and P2 are recorded. At this time, the rotating magnetic head 5 scans, for example, the recording track T2, and at the same time as the head 5 finishes scanning the recording track T2, the rotating magnetic head 6 starts scanning the recording track T3. are used alternately to perform recording scanning of recording tracks T4 +'T2 + . . . .

During reproduction, the head 5 is at the starting point position of the recording track Tz at time to, and at this time the cylinder I? is synchronized with the cylinder rotation. Luska (generated and input to the cylinder pulse input terminal 23. Due to this i'? Also becomes ■. The H output of the second OFF'25 causes the switcher 26 to apply the output (PI acid component) of the first BPF 21 to the first detector 27 connected to the first sample water field circuit 31. 20BPF 22 output (Pz acid component, second
The second wave detector 28 is connected to the sandal hold circuit 32. After the above-mentioned time t0, the head 5 scans the track T2, and the head 5 scans the first . The second arrow signal Pi tP2 is reproduced together with the recorded information on the track T2, and is input to the input terminal 20. From this reproduced video signal, the first . Second BPF 21, 22 frequency fx
, the first of fz. Second /zo pilot signal P1yP2
The components are extracted and passed through the switcher 26 to the first . After being rectified and detected by the second detectors 27 and 28, the first. It is input to the second Sanzor hold circuit 31, 32. The Q output of the first FF 24 is input to the first time constant circuit 29, and the output of this first time constant circuit 29 is input to the first FF 24.
At the same time as the Q output rises to H, it rises to H. Then, the output of the first time constant circuit 29 falls to 9L (low level) at time t1 corresponding to the timing when the head 5 is positioned at sl in FIG. 2 after the set time. This first
At the falling edge of the output of the time constant circuit 29, the first . The second sample and hold circuits 31 and 32 operate to detect the frequencies fl and f2 components in the reproduced video signal.
7. Hold each output level of 28. Both of these hold levels are provided to the differential amplifier 33. That is, the output of the differential amplifier 33 is the first . When the magnitudes of the second pilot signal Pl, P, and components are equal, if the pick head 5 is exactly in the center of the tracks Tl and T3, it will be 0, and the head 5 will be shifted to the Ti side or the T2 side. In this case, the signal PH or the P2 component takes a positive or negative value compared to the other. This is output as a tracking signal from the output terminal 34, and the relative position of the left side of the head 5 is corrected accordingly.

Next, video signal reproduction is switched to the rotary head 6 and the recording track T3 is scanned. Here, at the same time as the head 6 starts scanning the track T3, a cylinder pulse is input from the terminal 23, the first FF 24 is inverted, its 100 output becomes H, and the output of the second time constant circuit 30 becomes H. . At this time, since the second FF 25 is not inverted, the switcher 26 maintains its previous state. When the head 6 is located at a position corresponding to 82 in FIG. 2, the set time of the second time constant circuit 30 expires and its output falls, and the first . The second sample and hold circuits 31 and 32 operate, and the first sample and hold circuits 31 and 32 operate. Levels corresponding to the magnitudes of the second pilot signal P1 and P2 components are held, a tracking error signal is output from the differential amplifier 33, and tracking correction is performed.

When the head 6 finishes scanning the track T3,
When the head 5 is written again, the track T4 is scanned. Depending on the cylinder pulse at this time, the first. Second
OFF24 and OFF25 are both inverted, and the output of the second FF25 becomes L, so the switcher 26 operates, and the first BPF
The output of 21 is given to the second detector 28, and the second BPF2
2 is switched to be applied to the first detector 27. As can be seen from FIG.
Since the positional relationship between the two positions is reversed from that in the previous case, this is to make the positive and negative polarity of the tracking error signal the same as in the previous case.

Thereafter, similar operations are repeated to sequentially track each track.

Tracking correction control based on the tracking error signal outputted from the output terminal 34 is performed by controlling a cab stan motor, driving a movable head using a piezoelectric device, etc.

In this way, tracking errors are detected based on the amount of mixed signals of different frequencies recorded in adjacent tracks on both sides of the reproduced track. Therefore, the tracking error detection position and the actual tracking position match, and highly accurate and highly stable tracking control can be performed. Furthermore, if the recording positions of the no-kilot signals p1, p are set within the vertical retrace section of each track as described above, ideal tracking control can be realized without the risk of adversely affecting the video signal.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without changing the gist thereof.

For example, although the above embodiment has been explained using a rotating two-head type VTR as an example, magnetic recording in which a large number of recording tracks are arranged in parallel can be used regardless of the number of heads, the type of recorded information, or the type of recording medium. It can be applied to any playback device.

In addition, in the same embodiment, a case has been described in which, in a VTR, the main pilot signal is recorded in the section where the vertical retrace signal is recorded. The recording position of the i4 lot signal and the number of recording locations on the track can be arbitrarily selected as long as the condition that recording is performed is satisfied.

Furthermore, in the same embodiment, the pilot signals of two different frequencies were recorded in a staggered manner, but in this case, the adjacent pilot signal recording portions were partially erased. Good too.

In addition, if, for example, the iR pilot signals of three or more frequencies are used, and the order of the three types of mother pilot signals is determined in advance and the switching at the time of detection is performed accordingly, the iR pilot signal can be placed at the same position. You can also record it.

〔Effect of the invention〕

According to the present invention, it is possible to provide a magnetic recording and reproducing method that can perform good tossicking control without providing a control track and can also realize effective use of the recording surface of a recording medium.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram showing an example of the configuration of a conventional method.
The figure is a diagram for explaining recording and reproducing states in one embodiment of the present invention, FIG. 3 is a block diagram showing the main part configuration of the embodiment, and FIG. 4 is a waveform of each part for explaining the embodiment. Illustrated. 21.22... Bant Hasfir p, 24.25...
・Frizzo Frozzo circuit, 26...Switcher, 27
．． 28...Detector, 29.30...Time constant circuit, 3
1.32...Sample and hold circuit, 33...Differential amplifier. Applicant's agent Patent attorney Takehiko Suzue No. 2 Leap No. 4 Figure 1295. . Oh

Claims (1)

[Claims] In a magnetic recording/reproducing device in which a large number of recording tracks are arranged in parallel, during recording, pilot signals of different frequencies are present at substantially corresponding positions on both sides of one track, and can be distinguished from recording signals on intermediate tracks. A Nokilot signal is recorded on each recording track in such a way that the Nokilot signal is recorded in the same manner as the above-mentioned frequency. During playback, the Nokilot signal with the above frequency is detected from the tracks on both sides of the playback track, and the difference signal between the detection levels of the two is used as a tracking error signal. Magnetic recording and reproducing method 0 characterized by controlling tracking position