JPS62246163A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To discriminate the mode in case of not only slow reproducing but also frame feed reproducing and automatically change the mode in accordance with the discrimination result by reading a lock signal when a magnetic tape is stopped and discriminating the recording mode of the magnetic tape in accordance with the pattern of the read lock signal. CONSTITUTION:An ATF servo circuit 2 generates a tracking error signal from beat components of a reproduced pilot signal and a reference pilot signal and outputs this tracking error signal to a capstan servo circuit 3. When the magnetic tape is stopped and two pilot signals f2 and f1 are reproduce successively in one field period, beat components of the reproduced pilot signal f1 and the reference pilot signal are detected as the lock signal. Consequently, the lock signal is in the low level when the reference pilot signal is f2, and the lock signal is in the high level when the reference pilot signal is f4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing apparatus, typified by a video tape recorder, which records and reproduces video signals on inclined tracks using a rotating head.

[Summary of the invention]

In the present invention, for example, when performing slow playback.

The recording mode is determined from the pattern of the lock signal when the magnetic tape is stopped.

[Conventional technology]

FIG. 5 is a block diagram for slow playback in a video tape recorder as a conventional magnetic recording and playback device. The reference pyrobe No. 842 generation circuit 1 outputs a predetermined reference pilot signal (Fig. 6 (C)) to the ATF servo circuit 2 in synchronization with the input head switching pulse (SWP) (Fig. 6 (a)). do. Further, the ATF servo circuit 2 is inputted with a reproduced pilot signal (FIG. 6(b)) reproduced by a rotary head (not shown). Tracking pilot signals f1 to f4 of four different frequencies are sequentially recorded on each inclined track of a magnetic tape (not shown).

For example, when the mode is set to standard mode (SP mode) and slow playback is performed at 1/3 of that speed.

The magnetic tape is repeatedly run for 2 fields and stopped for 4 fields.

Therefore, a capstan drive signal (Fig. 6(d)) is input to the capstan servo circuit 3 that drives the capstan, and when the drive signal is at a low level, the rotation of the capstan is stopped, and when the drive signal is at a high level, the ATF The capstan is rotated in response to a tracking error signal from the servo circuit 2. The tracking error signal is generated from the beat components of the reproduced pilot signal and the reference pilot signal. That is, each of the pilot signals f to f4 has a difference in frequency between f, f2, f, and f4 of approximately 16 kHz, f.

The frequency difference between , fl, f, and f4 is selected to be about 46 KH2, respectively, and is generated by the reference pylon l-signal and the regenerated pilot signal as a cross-storage component from the left and right adjacent inclined tracks. 16kHz
and 46K! (A tracking error signal is generated by the level difference between the beat components of z.

When a manual changeover switch (not shown) is operated, an S P/L P changeover signal is input to the capstan servo circuit 3, and the running speed of the magnetic tape during playback is changed according to the recording mode. Time mode (L
In the P mode, the speed of the magnetic tape is slower than in the SP mode.

[Problem that the invention seeks to solve]

In this way, conventional magnetic recording and reproducing devices switch between SP mode and LP mode by operating one manual switch, so it is possible to accidentally transfer a magnetic tape recorded in SP (LP) mode to LP (SP) mode. If the recording mode is changed in the middle of one magnetic tape even if the mode is set correctly at the beginning, noise bars will appear on the screen, making it look childish. Further, even if the user knows that the mode setting is incorrect due to the occurrence of noise bars, the user cannot switch the mode during slow playback, and must temporarily stop slow playback in order to switch modes.

[Means for solving problems]

The present invention provides a magnetic recording/reproducing device in which running of the magnetic tape is stopped and a rotating head is used to trace an inclined track, and after running the magnetic tape for a predetermined length, the running is stopped, and the inclined track that was previously traced by the rotating head is By repeating the operation of tracing different inclined tracks, a lock signal is generated from the reproduced pilot signal reproduced from the magnetic tape and the reference pilot signal output from the reference pilot signal generation circuit, and locking is performed when the magnetic tape is stopped. It is characterized by reading the signal and determining the recording mode of the magnetic tape from the pattern of the read lock signal.

[Effect]

The operation in which the magnetic tape is stopped after running for a predetermined length is repeated, and at this time, the rotary spatula 1- traces the inclined track and a reproduction signal obtained is output.

For example, slow playback is performed. A lock signal is generated from the reproduced pilot signal and the reference pilot signal obtained at this time, and the pattern of the lock signal when the magnetic tape is stopped is detected to determine the recording mode.

〔Example〕

FIG. 1 is a block diagram of a magnetic recording/reproducing apparatus of the present invention, and parts corresponding to those in FIG. 5 are given the same reference numerals.

In FIG. 1, reference numeral 11 denotes a pulse generation circuit, which generates and outputs a predetermined sampling pulse in synchronization with an input head switching pulse (SWP). A reading circuit 12 reads the lock signal output from the ATF servo circuit 2 and outputs the read signal to the detection circuit 14 or 15 via the switching circuit 13. Detection circuit 14.1
5 detects each predetermined pattern of the signal from the switching circuit 13 and outputs the detection output to the pulse generating circuit 16. The pulse generation circuit 16 sends a control signal to the capstan servo circuit 3. corresponding to the input SP/LP switching signal. Switching circuit 1
3 and a display device 17.

However, for example, magnetic tape recorded in LP mode has twice the recording time as SP mode.

If the SP mode is selected and playback is performed at a slow speed of 1/3, the transition from each inclined track to Fig. 2 (b) is synchronized with the head switching pulse (Fig. 2 (a)) that inverts every field. A pilot signal as shown is regenerated.

When the magnetic tape is running, a pair of rotating heads A and B having mutually different azimuths each sequentially trace two inclined tracks at the same time.

On the other hand, when the magnetic tape is stopped, one of the pair of rotary heads A and B (for example, rotary head A) and the special reproduction rotary head A' of the same azimuth are connected to the same two
I-race on the book's inclined track with a slight incline (4th
Figure), 1! Assuming that the cross 1-direction component from the is contact track is ignored, when the magnetic tape is stopped, for example, pilot signals f2 and f□ are sequentially reproduced during one field (one trace), and the magnetic tape is running. Sometimes pilot signals f1 to f4 are sequentially reproduced during two fields (FIG. 2(b)).

On the other hand, the reference pilot signal generating circuit 1 generates data for each field in synchronization with the head switching pulse in a sequence (f4, f, . . .
When the magnetic tape is stopped, the same reference pilot signal as in the field immediately before the magnetic tape is stopped is generated (Fig. 2 (C)).
. The ATF servo circuit 2 generates a tracking error signal in a known manner from the beat components of approximately 16 KHz and approximately 46 KHz generated from this reproduced pilot signal (crosstalk component) and the reference pilot signal, and captures it. Output to stun servo circuit 3. Further, the ATF servo circuit 2 generates a tracking servo lock signal from the beat components of the reference pilot signal and the reproduced pilot signal. This lock signal has a frequency of approximately 46 KH, for example.
It is generated by comparing the level of the beat component of approximately 46 KHz with a predetermined reference level, and when the beat component of about 46 KHz is above the reference level, it is considered to be a high level, and when it is less than the reference level (including zero), it is considered to be a low level. . ATF servo circuit 2
A signal obtained by multiplying the head switching pulse by 2i5 (Fig. 2 (d)) is scanned by the pulse generation circuit 11 as a sampling pulse, and the ATF servo circuit 2 samples the lock signal when this sampling pulse is at a low level. and holds the sampled signal when the level is high.

When the magnetic tape is stopped and the two pilot signals f2 and f are sequentially reproduced during one field period, the first half field is the hold period and the second half field is the sampling period, so in the end the reproduced pilot signal A beat component between the f-engine and the reference pilot signal is detected as a lock signal.

Therefore, the lock signal becomes low level (L) when the reference pilot signal is f2, and becomes high level (H) when the reference pilot signal is f4 (FIG. 2(e)).

This lock rit number output from the ATF servo circuit 2 is input to the reading circuit 12. A capstan drive signal (FIG. 2(f)) is input to the reading port 'JPt12, and the reading circuit 12 receives a lock signal when this drive signal is at a low level (when the magnetic tape is stopped). Read the level of. For example, the level (polarity) of the lock signal immediately after the drive signal becomes high level (the lock signal immediately before the drive signal becomes high level is held) is read. This read signal is input to the detection circuit 14 or 15 via the switching circuit 13. - When a manual switch (not shown) is operated and an SP/LP switching signal specifying SP mode is input to the pulse generation circuit 16, the pulse generation circuit 16 outputs a control signal to the switching circuit 13,
The signal from the reading circuit 12 is supplied to the detection circuit 15.

Conversely, when the LP mode is designated, the signal from the reading circuit 12 is supplied to the detection circuit 14.

Since the SP mode is now designated, the display device 17 displays this fact, and the capstan servo circuit 3 runs the magnetic tape at about 1/3 of the speed of the SP mode, and the switching circuit 13 runs the The signal from the circuit 12 is output to the detection circuit 15. The detection circuit 15 detects a lock signal pattern when a magnetic tape recorded in the LP mode is played back (slow playback) in the SP mode.

That is, the detection circuit 15 detects that the signal from the reading circuit 12 is L.
This pattern is detected when the signal changes sequentially to -+H+L-+H. When detecting this pattern, the detection circuit 15 outputs a detection signal to the pulse generation circuit 16, inverts the control signal, and outputs a signal when the LP mode is selected. As a result, the capstan servo circuit 3 moves the magnetic tape to the L
The vehicle is run at approximately 1/3 the speed of the P mode, and the 1 display circuit 17 displays that the vehicle has been switched to the LP mode.

The switching circuit 13 is also switched to supply the signal from the reading circuit 12 to the detection circuit 14.

When the detection circuit 15 does not detect a pattern changing from L→H→L-DH, in other words, when the SP mode is selected and the recording mode of the magnetic tape is also the SP mode, the detection circuit 15 does not generate a detection output. .

On the other hand, when a magnetic tape recorded in SP mode is played back slowly at 1/3 speed by specifying LP mode, the capstan is rotated for a period of 2 fields by the 5 capstan drive signal (Fig. 3 (f)). run) and stop the capstan (stop the magnetic tape) for a period of 4 fields.
to let

The head switching pulse (Fig. 3(a)) is doubled to make the sampling pulse (Fig. 3(d)) 11), and the reference pylon Mn (Fig. 3(C)) is set for each field. The generation in reverse sequence is similar to the case described above. In this case, each pilot signal f1 to f4 is sequentially reproduced for a period of 6 fields from when the magnetic tape is stopped to when the next run ends and the magnetic tape is stopped (Fig. 3(b)). In the section where the reproduced pilot signal f□ and the reference pilot signal f2 are generated, the frequency of the beat component is approximately 16 KHz, so the lock signal becomes L, and in the section between the reproduced pyrobe 1-signal f3 and the reference pilot signal f2, the lock signal becomes L. Approximately 46
Since a KHz beat component is generated, the lock signal becomes H. On the other hand, in the section between the reproduced pilot signal f2 and the reference pilot signal f4, the frequency of the beat component is approximately 30
It becomes KHz.

Since the image frequencies are the same in the sections of the reproduced pilot signal f4 and the reference pilot signal f4, in principle no beat occurs, and the lock signal in these sections becomes L (or X (undefined)). That is, reading circuit 1
2 is the read signal of the lock signal, L-+X (L
)→H-+X (L) Outputs a signal with a pattern that changes. This signal is supplied from the switching circuit 13 to the detection circuit 14. The detection circuit 14 is: (7)L-)X (L)
When a pattern changing to 4H-+X (L) is detected, a detection signal is output to the pulse generation circuit 16. At this time, the pulse generating circuit 16 switches the control signal from the LP mode to the SP mode. Therefore, the capstan servo circuit 3 causes the magnetic tape to run at 1/3 the speed of the SP mode, and the 1 display device 17 displays that the SP mode has been selected. Further, the switching circuit 13 is switched so that the signal from the reading circuit 12 is output from the detection circuit 14 to the detection circuit 15. Therefore, the recording mode changes from SP mode to LP again.
The pattern of the lock signal when the mode is changed is detected.

When the detection circuit 15 does not detect the above-mentioned pattern (L
Playback of magnetic tape recorded in P mode in LP mode (
During slow playback), no detection signal is output, and at this time, the capstan servo circuit 3 runs the magnetic tape at 1/3 the speed of the LP mode, and the display device 17 selects the LP mode. It shows that.

Although the detection circuits 14 and 15 are provided separately in the above description, it is also possible to detect both patterns with one detection circuit. At this time, since the switching circuit 13 becomes unnecessary, the detection circuit can be integrated into the reading circuit 12.

〔effect〕

As described above, the present invention relates to a magnetic recording/reproducing device.

Repeat the operation of stopping the running of the magnetic tape and tracing a tilted track with the rotating head, stopping the running of the magnetic tape after running for a predetermined length, and tracing a tilted track different from the tilted track traced last time with the once-rotating head. , generates a lock signal from the reproduced pilot signal reproduced from the magnetic tape and the reference pilot signal output from the reference pilot signal generation circuit, reads the lock signal when the magnetic tape is stopped, and calculates the read lock signal. Since the recording mode of the magnetic tape is determined from the pattern, the lock signal when the magnetic tape is stopped is used, and the mode can be determined and associated modes not only during slow playback but also during frame-by-frame playback. can be changed automatically.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the magnetic recording/reproducing apparatus of the present invention, and FIG.
The figure and FIG. 3 are the timing charts. FIG. 4 is a plan view showing the state in which a rotary head traces the magnetic tape, FIG. 5 is a block diagram of a conventional magnetic recording/reproducing apparatus, and FIG. 6 is a timing chart 1 to 1 of the conventional magnetic recording/reproducing apparatus. 1...Reference pilot signal generation circuit 2...ATF servo circuit 3...Capstan servo circuit 11...Pulse generation circuit 12...Reading circuit 13...Switching circuit 14.15...Detection Circuit 1G...Pulse generation circuit 17...Display device or higher

Claims (1)

[Claims] Stopping the running of the magnetic tape, tracing an inclined track with a rotating head, stopping the running after running the magnetic tape for a predetermined length, and tracing the inclined track different from the inclined track traced last time with the rotating head. By repeating this operation, a lock signal is generated from the reproduced pilot signal reproduced from the magnetic tape and the reference pilot signal output from the reference pilot signal generation circuit, and the lock signal is generated when the magnetic tape is stopped. A magnetic recording/reproducing apparatus characterized in that the recording mode of the magnetic tape is determined from the pattern of the read lock signal.