JPS6260102A - Magnetic tape for detection of linearity of recording track - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic tape for detecting track bending in a magnetic recording/reproducing apparatus (hereinafter simply referred to as a VTR), and in particular, for detecting track bending in a magnetic recording/reproducing apparatus (hereinafter simply referred to as a VTR).
Convert it to an M signal, compress it in time and record and play it back, and
This relates to a magnetic tape for detecting track curvature in a VTR that uses a 4-frequency pilot signal as a tracking method during playback.0 Conventional technology In a 2-heck helical scan VTR, one image is recorded as one line. In this case, the recording track should originally be recorded in a straight line, but in reality it is recorded in a curved line due to the mechanical precision of the tape running system. If a VTR is manufactured with the deck having a unique curvature, for example, when a tape recorded with a "/TR" with a human curvature is played back on a VTR with a curvature of B, the playback head The playback scan will be mistracked by the amount corresponding to the difference in curvature between the two decks.As a result, the playback image quality will deteriorate by the amount of mistracking.When manufacturing a 0VTR, the above problem with compatible playback will be avoided. In order to solve this problem, the track curvature of each deck is adjusted so that the track curvature is below a certain value.The method is to play back a master tape on which tracks are recorded in a straight line, and then use the playback signal to A signal indicating the track curvature, which will be described later, is obtained, and the running height of the tape is raised or lowered using limiter posts located on both sides of the cylinder or cylinder, which has a built-in rotary head, so that the track curvature of the deck is kept below a certain value. adjust.

There are two ways to know track curvature.

The first method is a method used when manufacturing a VTR that performs tracking control during playback using a control signal. To summarize the procedure, turn the tracking volume to mistrack to one side, and memorize the waveform of the playback output at that time. Next, mistrack to the opposite side, look at the waveform of the playback output at that time, and adjust the running by looking at the amount of change in both outputs.

The second method is adopted as a unified standard for BSM VTRs and is used when manufacturing VTRs that perform tracking control using four-frequency pilot signals.

The specific explanation and superiority of the first method and the second method are as follows:
This is described in Japanese Patent Application No. 59-52503.

Since the present invention is an extension of the method described in Japanese Patent Application No. 59-52503 to display track curvature in the PGM area, the second method will be explained in some detail.

FIG. 9 shows the magnetization trajectory where the pilot signal was recorded. In the figure, BOrm 1. B1... is a recording track recorded by the B head and the mu head, and the head 90
1 shows a state where the track is curved at the position where it starts to contact the tape. Arrow 902 indicates the scanning direction of the head. In each recording track, each pilot signal indicated by f1 to f4 is recorded together with a video signal, and each pilot signal is continuous within one recording track.The signals indicated by Of1 to f4 have the frequencies shown in Table 1. It's a signal.

Since each pilot signal is a relatively low frequency signal, the loss due to the azimuth effect is so small that it can be ignored. Therefore, even if the B head plays back the track M1 (i=1.2.s,...) with different azimuth angles,
The pilot signal can be regenerated with almost no loss. Further, even if the head does not reproduce the adjacent track, the pilot signal recorded on the adjacent track can be reproduced as a crosstalk signal.

If, for example, only the signal fl from the reproduced pilot signal is extracted by a tuning circuit, the signal will have the waveform shown in FIG. In the same figure, Fig. 10 (&) is a head switching signal (hereinafter referred to as H, s + w signal), which is a 3-pin signal that is phase-synchronized with the cylinder containing a rotating head.
It is a signal of 0 Hz (N, T2C). Same figure (
The waveform shown in b) is the waveform when only the -f1 signal component is extracted. That is, in FIG. 9, the head 90
The fl signal obtained when the head 1 scans on track B1 is the point at which the head starts contacting the tape (lower end in the drawing).
is the maximum, and thereafter a constant level of 11 is played. The level of fl reproduced when the head scans over track B1 is almost uniform. When scanning over track B1, there is a minimum at the point where the head starts contacting the tape.

Further, when the head scans the track 2, the fl signal is not reproduced. Therefore, the waveform of the reproduced signal fl changes as shown in FIG. 10(b). In FIG. 1Q, the difference in the signal waveform of fl reproduced during the BolBl period corresponds to track curvature. Therefore, the track curvature may be adjusted so that the difference in the envelope of the f1 signal reproduced during the rainy period becomes constant. The reason for looking at the difference in the output of the f1 signal during the rainy period is that, for example, when the output is not reproduced at the point where the head starts contacting the tape due to a poor head touch, the signal waveform of fl during the BO+B1 period is due to track curvature. This is because the waveform shown in the B1 period is output even when there is no period. The waveforms shown in FIG. 10(b) can be seen superimposed on an oscilloscope as shown in FIG. 11. In Figure 11 (a)
(b) is a signal obtained by detecting and rectifying the signal shown in Fig. 10 (b) and superimposing it on an oscilloscope. Needless to say, the signal shown in Fig. 11 (L ) (Just trigger the oscilloscope with the D signal.0 The above is a method of extracting one type of pilot signal and checking the track curvature.

The above-mentioned method shown in Japanese Patent Application No. 59-52503 is based on PCM
There is no mention of how to view track curvature in a region. 1
It is difficult to observe track bending in the PCM region using the method described above using the magnetization pattern defined by the unified standard for 3 mm VTR. This problem will be explained below.

FIG. 12 shows the magnetization trajectory where the PCM signal was recorded. 2
In a head-type helical scan type VTR, a magnetic tape is wound around a drum at 221 degrees and run. -)2
36 degrees out of 21 degrees are used for recording PCM signals, and video signals are recorded in the remaining portion. Arrow xo indicates the transport direction of the magnetic tape, and arrow x1 indicates the scanning direction of the magnetic head. FIG. 13 shows the recorded magnetization locus of the pilot signal. In the unified standard of 9s+aVTH, the same pilot signal is recorded at the same time. In a two-head helical scan type VTR, in FIG. 13, when the human head is located at the end of track 1, the B head is located on the boundary line between fl and 12 shown in the Ih) rack. Therefore, in the method of recording the same pilot signal at the same time,
The magnetization trajectory becomes as shown in FIG. 13.

FIG. 8 shows the time relationship between the H and SW multiplied signal regenerated pilot signals. In the same figure, (IL) is H, gw
(b) shows the pilot signal reproduced by the B head, and (C) shows the pilot signal reproduced by the M head.

It is difficult to reproduce each track of the magnetization locus shown in FIG. 13 and extract only the fl signal, thereby continuously observing the track curvature between the PCM area and the video signal area. This is because the same pilot signal is not recorded on one recording track, so track curvature between the PCM section and the video signal section cannot be continuously observed. In addition, since 8 on track M1 and fl on track 81 in FIG. 13 are at the same time, there is a drawback that when looking at track bending in the PCM section, part of the tracks in the video signal area cannot be seen at the same time. .

Problems to be Solved by the Invention However, when winding a rotating drum at 221 degrees and adjusting the track curvature of a track for recording a PCM signal and a video signal, the conventional magnetization pattern is used to wrap the entire length of one track. It was not possible to display track curvature.0 The present invention provides a magnetic tape that continuously detects track curvature over the entire length of one track.0Means for solving the problem. This is a magnetic tape for detecting the linearity of a recording track in which the same pilot signal is recorded on one continuous track consisting of an area for recording signals and an area for recording video signals.

Operation According to the above-described configuration, the present invention detects track curvature based on the difference in reproduction level of one type of pilot signal obtained when reproducing tracks before and after a track in which one type of pilot signal is recorded.

Embodiment The present invention attempts to obtain the regenerated pilot signal shown in FIG. 7 by the method described later.
! L) is the H, sw times signal (b) is the pilot signal reproduced by the B head, and (0) is the pilot signal reproduced by the 5-head.

An embodiment of the recording and reproducing circuit for obtaining the reproduced pilot signal shown in FIG. 7 will be described below. FIG. 1 shows a specific example of the circuit for recording the pilot signal, and FIG. FIG.

In FIG. 1, a PG multiplied signal is input from a terminal 101. This is a rectangular wave signal that rises or falls at the start of the PG double signal PCM signal, and is the signal indicated by (a). Delayed by 36 degrees in the PG double signal delay circuit 102, H,
SW signal port) is created.

104 and 105 are inverting circuits, and 108 and 107 are sector reset type 7 lip-flops (hereinafter referred to as 5R-FF). In the figure, S is a set terminal, and R is a reset terminal, both of which are assumed to be triggered by the rising edge of the input signal. The output signals of the 5R-FFs 106 and 107 become the signals (E) and (E) shown in FIG. 1
Reference numerals 08 and 109 designate frequency divider circuits that are triggered by the rising edge of the input signal, and their output signals are the signals shown in (G) and (B). 110 is a differentiating circuit, and the signal (T)
The output signal of the divider circuit 109 is reset at the rising edge of . By doing so, the phase relationship (polarity) between the signals (g) and (b) can always be the same. This is necessary to sequentially and cyclically output signals 11 to f4. Reference numerals 0111 and 112 are pilot signal generation circuits that output four types of pilot signals.

The type of pilot signal output is determined by the input 2-bit signal. The input/output relationship is shown in Table 2, taking the pilot signal generation circuit 111 as an example.

Table 2 Output signals of pilot signal generation circuits 111 and 112 (
c) and ii) result in the signals shown in FIG. As is clear from FIG. 2, in the pilot signal (c) recorded by the head B, f and f3 are continuously recorded in the area of the PCM signal and video signal, and the pilot signal recorded by the head B is ), fl and f4 are continuously recorded in the PCM signal and video signal areas. fl at signal (c)
Since the pilot signals to fl and 14 and signal 14 and 14 and fl during the period when the heads M and B are not in contact with the tape, these signals are not recorded on the tape.

In FIG. 1, 113 and 114 are signal processing circuits that output FM-modulated video signals and PCM signals.

However, when creating a master tape used only for the purpose of displaying track curvature, the output signals of the signal processing circuits 113 and 114 may be bias signals for recording pilot signals. Each signal of circuits 111 to 114 is
As shown in FIG. 1, each signal is superimposed, and the recording amplifier 11
5 and 116. Recording amplifier 115, 116
The ρ output signal is sent to heads 119 and 120 via rotary transformers 117 and 118. With the above circuit configuration, each signal shown in FIGS. 2(c) and 2) can be recorded on the magnetic tape.

Next, the reproduction circuit will be explained.

FIG. 3 is a diagram showing a specific embodiment of the reproduction circuit, FIG. 4 is a detailed block diagram of the track bending detection circuit, FIG. 5 is a diagram showing the magnetization locus including the PCM region, and FIG. 4 is a waveform diagram of each part in FIG. 4. FIG.

In FIG. 3, signals reproduced in color from each head 301 and 302 are supplied to head amplifier circuits 305 and 306 via rotary transformers 303 and 304. The output of each head amplifier is supplied to an electronic switch 307, and a signal reproduced by one of the heads is selectively extracted to a low-pass filter 308 for extracting a pilot signal. Electronic switch 307 is switched depending on the level of the signal supplied from manual switch 316. For example, if the manual switch signal is High level, B
A signal reproduced from the head is extracted, and if the level is low, a signal reproduced from the human head is extracted. The signal supplied to the manual switch is the signal shown in FIG. 2, which is an inverted version of the signal shown in FIG. The signal (/→ is shown in FIG. 6. In FIG. 6, the signal (for men, there is a PG double signal, SI) is the H, SW signal. The manual switch 316 in FIG. This switch is used to select whether to display the curvature or the curvature of the track recorded by the B head.The pilot signal extracted by the low-pass filter 308 is sent to the track curvature detection circuit 309 and the tracking error signal generator. The tracking error signal generation circuit is supplied to the circuit 310.The detailed operation of the tracking error signal generation circuit is described in various published patents that perform control using four-frequency pilot signals, so a detailed explanation will be given here. Although omitted, the outline is that the pilot signal to be reproduced and the reference signal supplied from the terminal 311 are balanced-modulated, and the reproduction level difference between the respective parts (i.e., the reproduction level signals) reproduced from both adjacent tracks of the track scanned by the head is This is a circuit that outputs.

Circuit 312 is a sample and hold circuit. Terminal 313
For example, the sample pulse supplied from Q0 in FIG. The phase error signal is supplied to the circuit as a phase error signal.

Next, the track bending detection circuit 309 will be explained.

FIG. 4 is a diagram showing detailed blocks of the track bend detection circuit. In the figure, a 0 circuit 402 to which a reproduced pilot signal is supplied from a terminal 401 is a tuning circuit that extracts a one-frequency pilot signal, for example, a fl signal. P
FIG. 6 shows the magnetization locus including the CM signal region. The waveform of the fl signal reproduced at this time is shown in Figure 6 (
4) As already explained in the conventional example, (
B6 and B of signals shown in 3)
The regenerated fl pilot signal is transmitted through circuit 4 shown in FIG.
The signal is detected and rectified at step 03 and supplied to a sample and hold circuit 404. The circuit after the sample/hold circuit 12i404 is a processing circuit for extracting the level difference between the signals reproduced during the period B5 and B;. terminal 405
The sample signal supplied from H, sw times the signal N
It is a pulse of an appropriate frequency that is divided and phase-synchronized with the H and SW times signals. The detected and rectified pilot signal is sampled and held in the form of one frame period (H, SW same period divided into N). 406 is an analog-to-digital conversion circuit. This is a delay circuit designed to delay the signal by a period of time.Each signal before the delay and after the delay is subtracted and outputted as an analog signal by the digital-to-analog conversion circuit 408.Therefore, the signal obtained at the terminal 409 is It is a signal according to the

Effects of the Invention As is clear from the above explanation, if the magnetic tape of the present invention is used, the combined PCM signal area and video signal area can be
Since the track curvature of the recording track of a book can be displayed as a continuous track curvature over the entire area, it is possible to adjust the track curvature including the PGM area when manufacturing a VTR.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a recording circuit for producing the magnetic tape of the present invention, FIG. 2 is a waveform diagram of each part of FIG. 1, and FIG. , a block diagram showing an embodiment of a reproduction circuit for detecting track bending, FIG. 4 is a block diagram of a track bending detection circuit,
FIG. 6 is a magnetization trajectory diagram according to the present invention, FIG. 6 is a waveform diagram of each part of FIGS. 3 and 4, and FIG. 7 is a waveform diagram showing the temporal relationship of the pilot signal reproduced from the magnetization trajectory according to the present invention. , Fig. 8 is a waveform diagram showing the temporal relationship of the pilot signal reproduced from the conventional magnetization locus, Fig. 9 is a magnetization locus diagram of the pilot signal in the recording area of the video signal, and Fig. 10 is a waveform diagram showing only the pilot signal of fl. The reproduced waveform diagram, Figure 11 is the 10th
Waveform diagram when the waveforms shown in the figure are superimposed on an oscilloscope, No. 12
The figure is a magnetization trajectory diagram including the PCM signal region, and Figure 13 is the PC
FIG. 3 is a magnetization locus diagram of a pilot signal including an M signal region. 106.107...Set reset flip-flop, 111,112...Pilot signal generation circuit, 115,116...Record amplifier circuit, 117.118...・Rotary transformer, 1
19°120...Rotating head, f1~f,...
...Pilot M, 30s, 306...
・Head amplifier, 316...Manual switch, 3
12. River...Sample bold circuit. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure 2 (+) Figure 4 Figure 5 Figure 6 Figure 7 (d) Bo A+ B+ Az
(b) Nico Nico ni] 22 Figure (0) Nico Nico τCo Figure 8 Figure 9 Figure 10 Figure 11 (of) H-3WL-111-111 Figure 12 X. Figure 13

Claims (1)

[Claims] An area for recording a video signal and an area for recording a temporally compressed PCM signal are formed as one continuous recording track, and the area for recording the video signal and the PC
A magnetic tape for detecting the linearity of a recording track in a magnetic recording and reproducing device that records a pilot signal different from an area in which an M signal is recorded, wherein one type of pilot signal is continuously recorded on one continuous recording track. and every N tracks of the recording track group (N is an integer of 4 or more)
A magnetic tape for detecting linearity of a recording track, characterized in that the same pilot signal is recorded on the magnetic tape.