JPS62252558A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute the discrimination of a mode and to change automatically the mode accompanied to it even at the time of rewinding and reproducing by reading a pattern from a delayed reference pilot signal and a reproduced reproducing pilot signal and detecting a recording mode from the pattern. CONSTITUTION:A detecting circuit 15 detects the pattern of a locking signal when a magnetic tape recorded by an LP mode is reproduced by an SP mode. Namely, the detecting circuit 15 detects the pattern when the signal from a reading circuit 12 is successively changed in the sequence of L X H X, and when the pattern is detected, the detecting circuit 15 outputs the detecting signal to a pulse generating circuit 16 inverts a control signal and outputs the signal when the LP mode is selected. As a result, a capstan servo circuit 3 travels the magneic tape at the usual reproducing speed of the LP mode, for example, at the 9-fole speed, and a displaying circuit 17 displays that the LP mode is changed over. Consequently, for changing-over of a ode, it is not necessary to stop the high speed reproduction once.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] The present invention relates to a magnetic recording/reproducing device typified by a video tape recorder.

[Summary of the invention]

In the present invention, the reference pilot signal is delayed at a predetermined timing, and the recording mode of the magnetic tape, which is fast forwarding or rewinding, is detected from the pattern of the lock signal generated from the reference pilot signal and the reproduced pilot signal.

[Conventional technology]

FIG. 10 is a block diagram for fast forwarding or rewinding playback in an 8 mm video tape recorder as a conventional magnetic recording and reproducing device. The reference pilot signal generation circuit 1 outputs a predetermined reference pilot signal to the ATF servo circuit 2 in synchronization with the input head switching pulse (swp). Further, a reproduced pilot signal reproduced by a rotating head (not shown) is input to the ATF servo circuit 2. Tracking pilot signals f to f4 having four different frequencies are sequentially recorded on each inclined track of a magnetic tape (not shown).

For example, when a magnetic tape is fast-forwarded at a speed higher than the normal playback speed and a rotating head is traced across an inclined track to reproduce a video signal, the same head switching pulse as shown in FIG. 11(a) is applied. Figure (b)
A pilot signal as shown in (d) of the figure is regenerated, and a reference pilot signal as shown in (d) of the figure is generated. Similarly, when rewinding a magnetic tape, for example, in response to a head switching pulse as shown in FIG. 12(a),
A pilot signal as shown in (d) of the figure is regenerated, and a reference pilot signal as shown in (d) of the figure is generated. A tracking error signal is generated from the beat components of the reproduced pilot signal and the reference pilot signal. That is, each pilot signal f, to f, is f□ and f2, f, and f,
The difference between the frequencies of f2 and fl, and the difference between the frequencies of f and f4 are about 46 KHz each, and the crosstalk from the reference pilot signal and the adjacent tilted tracks on the left and right. A tracking error signal is generated by the level difference between the 16 KHz and 46 KH2 beat components caused by the reproduced pilot signal as a component. This tracking error signal is input to the capstan servo circuit 3, the capstan is driven, and the magnetic tape is run.

When a manual changeover switch (not shown) is operated, an SP/LP changeover signal is input to the capstan servo circuit 3, and the running speed of the magnetic tape during playback is changed over in accordance with the recording mode. In (LP mode), the speed of the magnetic tape is slower than in standard mode (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 a 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 a single magnetic tape even if the mode is set correctly at the beginning, the number of noise bars that appear on the screen will increase, which can be confusing. Ta. Furthermore, even if the user knows that the mode setting is incorrect due to an increase in the noise bar, the user cannot switch the mode during fast-forward or rewind playback, and must temporarily stop high-speed playback in order to switch modes.

[Means for solving problems]

The present invention provides a magnetic recording/reproducing device in which a magnetic tape is fast-forwarded or rewound at a speed higher than the normal reproduction speed, a rotating head is used to trace across a tilted track, a reproduction pilot signal is reproduced from a tilted 1-rack, and a reference It is characterized in that the reference pilot signal generated by the pilot signal generation circuit is delayed at a predetermined timing, a pattern is read from the delayed reference pilot signal and the reproduced signal to the reproducing pilot 1, and the recording mode is detected from the pattern.

[Effect]

The magnetic tape is fast forwarded or rewound and the rotating head traces across the sloping track.

At this time, a pilot signal previously recorded on the inclined track is reproduced. On the other hand, the reference pilot signal is delayed at a predetermined timing, and a lock signal is generated from the delayed reference pilot signal and the reproduced pilot signal,
The recording mode is detected from the pattern of the lock signal.

〔Example〕

FIG. 1 is a block diagram of a magnetic recording/reproducing apparatus according to the present invention, and parts corresponding to those in FIG. 10 are given the same reference numerals. In FIG. 1, reference numeral 11 denotes a pulse generation circuit, which generates and outputs delay pulses and sampling pulses in synchronization with input head switching pulses (swp). 12
is a reading circuit which reads the lock signal output from the ATF servo circuit 2 and sends the read signal to the switching circuit 13.
The signal is output to the detection circuit 14 or 15 via. Detection circuit 1
4.15 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, in response to the input S P/L P switching signal.
It is output to the switching circuit 13 and the display device 17.

However, for example, when a magnetic tape recorded in LP mode is played back in fast forward mode in SP mode, the rotating head traces across the inclined track as shown in Figure 2.
In this case, the speed of the magnetic tape during fast forwarding is 9 during normal playback.
).

At this time, pilot signals f□ to f4 are sequentially reproduced from the pair of rotary heads A and B that are switched by the head switching pulse (Fig. 3 (a)) (Fig. 3 (b)).
, is input to the ATF servo circuit 2.

On the other hand, the reference pilot signal generation circuit 1 generates a reference pilot signal (Fig. 3(d)) in synchronization with the head switching pulse.
) is generated and supplied to the ATF servo circuit 2. This reference pilot signal is delayed at a predetermined timing. That is, the reference pilot signal is delayed by a predetermined time T□ at a timing when a predetermined time T has elapsed from the rising or falling edge of the input head switching pulse.

This time T corresponds to approximately 1/9 of one field (half cycle of head switching pulse), corresponding to the running speed of the magnetic tape.
In addition, the width of time 18 is set to approximately 1/18 of one field. Therefore, the timing of delaying the reference pilot signal approximately coincides with the timing at which the peak of the RF multiplied signal (Fig. 3(e)), obtained when a magnetic tape recorded in SP mode is correctly fast-forwarded in SP mode, occurs. .

The ATF servo circuit 2 generates a lock signal and an error signal from this delayed reference pilot signal and the beat component of the reproduced pilot signal being reproduced at that time. This lock signal is generated, for example, by comparing the level of a beat component with a frequency of about 46 KHz and a predetermined reference level. The ATF servo circuit 2 is sampled with two pulses (FIG. 3(f), (g)) having opposite phases to each other from the pulse generating circuit 11. The ATF servo circuit 2 samples the lock signal when the sampling pulse 2 (third (g)) is at a low level, and holds the sampled signal when it is at a high level. Further, when the sampling pulse 1 (FIG. 3(f)) is at a low level, an error signal is sampled, and when it is at a high level, the sampling signal is held.

In Fig. 3, when the first sampling pulse 2 occurs, the reproduced pilot signal is fY and the reference pilot signal is f2, so the frequency of the beat component is approximately 16 KHz, and the lock signal (Fig. 3 (h)) is L. Become. When the second sampling pulse 2 is generated, the reproduced pilot signal is f3 and the reference pilot signal is f, so the frequency difference is about 62KHz, which is 16KHz which is normally obtained.
or 46KHz, so the lock signal is L (
or
z, and the lock signal becomes H. When the fourth sampling pulse 2 is generated, the regenerated pilot signal is fl and the reference pilot signal is f, so the lock signal is L(
or undefined (X)).

The locked signal held after sampling is output from the ATF servo circuit 2 and input to the reading circuit 12.

When a manual switch (not shown) is operated and an SP/LP switching signal specifying the SP mode is input to the pulse generation circuit 16, the pulse generation circuit 16 outputs a control signal to the switching circuit 13, and the pulse generation circuit 16 outputs a control signal from the reading circuit 12. The signal 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, and the capstan servo circuit 3 runs the magnetic tape at a speed of about 9 times the speed of the SP mode (fast forward), and the switching circuit 13 The signal from the reading circuit 12 is output to the detection circuit 15. The detection circuit 15 is L
A magnetic tape recorded in P mode is played back in SP mode (
Detects the pattern of the lock signal when the device is played (fast-forward playback). That is, the detection circuit 15 detects this pattern when the signal from the reading circuit 12 sequentially changes from L4X-)H to X. When this pattern is detected, 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 causes the magnetic tape to run at a speed nine times the normal playback speed in the LP mode, and the display circuit 17 displays that the mode 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 that changes from L-) do not.

That is, when the recording mode of the magnetic tape is SP mode, the reproduction pilot signal is as shown in FIG. 3(c). Since the frequency difference between this regenerated pilot signal and the reference pilot signal in Figure 3(d) is 16 kHz, the lock signal remains at L (Figure 3(i)).
).

On the other hand, when a magnetic tape recorded in SP mode is played back in fast forward at 9 times the normal playback speed by specifying LP mode, the trace locus on the magnetic tape becomes as shown in Figure 4, and the timing chart is The result is as shown in FIG. Since the regenerated pilot signal is not generated as shown in Figure 5(b) and the reference pilot signal is not generated as shown in Figure 5(d), the lock signal output from the ATF servo circuit 2 is shown in Figure 5(h). It becomes like this. i.e. in this case ro')
M No. (7) 'Turn 4J:, L - + X
-+ X -+ H-4H4x-*X→L. This pattern is detected by the detection circuit 14. Detection circuit 1
4 outputs a detection signal to the pulse generation circuit 16 when this pattern is detected. At this time, the pulse generation 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 a speed nine times the normal playback speed in the SP mode, and the display device 17 displays that the SP mode has been selected. Furthermore, the switching circuit 13 converts the signal from the reading circuit 12 into the detection circuit 1.
4 to '' to output to the detection circuit 15. Therefore, the pattern of the lock signal when the recording mode is changed from the SP mode to the LP mode 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 fast-forward playback), no detection signal is output, and at this time the capstan servo circuit 3 runs the magnetic tape at a speed nine times the normal playback speed in the LP mode, and the display device 17 selects the LP mode. It shows that it is being done.

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.

Next, when rewinding and playing back a magnetic tape recorded in LP mode in SP mode, the trace locus of the rotating head is
The timing chart is as shown in FIG. 7. In the same mode, when the running speed of the magnetic tape during fast forwarding is set to n times the normal speed, the speed during rewinding is set to n-2 times. In this way, the number of inclined tracks crossed by the rotating head during fast forwarding and rewinding is the same, and the number of noise bars generated on one screen can be made the same. Furthermore, if n is an odd number, noise bars will be generated. The position is fixed and it is easy to see. Therefore, in this embodiment, the speed of the magnetic tape during rewinding is set to seven times the normal speed.

In this case, the reproduced pilot signal is generated as shown in FIG. 7(b), and the reference pilot signal is generated as shown in FIG. 7(d). Therefore, the lock signal pattern is shown in the same figure (h).
As shown in , it changes as L-+X→H→X. This pattern is detected by the detection circuit 15. Recording mode is S
In the case of P mode, the reproduced pilot signal becomes as shown in FIG. 3(c), and the lock signal becomes as shown in FIG. 1(i).

Further, when rewinding and reproducing a magnetic tape recorded at 5p-i=- in the LP mode, the trace locus becomes as shown in FIG. 8, and the timing chart thereof becomes as shown in FIG. In other words, the regenerated pilot signal is as shown in Fig. 9 (b
), the reference pilot signals are generated as shown in (d) of the same figure, so the lock signal is generated as shown in (h) of the same figure, L − + L 4 X→X−)H→H→X→ Changes to X. This pattern is detected by the detection circuit 14.

When the recording mode is the LP mode, the reproduction pilot signal is generated as shown in FIG. 3(c), so the lock signal becomes as shown in FIG. 2(i).

In this way, the same pattern is generated during rewinding as during fast forwarding, so it can be operated in the same way as during fast forwarding.

Although the case where n = 9 has been described above as an example, it is clear that this value can be set to any value, preferably an odd number.

〔effect〕

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

The magnetic tape is fast-forwarded or rewound at a speed higher than the normal playback speed, the rotating head traces the tape across the inclined track, and the reproduced pilot signal is reproduced from the inclined track.The reference pilot signal generated by the reference pilot signal generation circuit is The signal is delayed at a predetermined timing, a pattern is read from the delayed reference pilot signal and the reproduced pilot signal, and the recording mode is detected from the pattern.
Even during rewind playback, it is possible to determine the mode and automatically change the mode accordingly.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the magnetic recording/reproducing apparatus of the present invention, and FIG.
4, 6 and 8 are plan views showing how the rotary head traces the magnetic tape, and FIGS. 3, 5, 7 and 9 are timing charts, Figure 10 is a block diagram of a conventional magnetic recording/reproducing device;
This figure and FIG. 12 are timing charts thereof. 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 16...Pulse generation circuit 17...Display device or higher

Claims (1)

[Claims] A reference pilot signal generated by a reference pilot signal generation circuit by fast forwarding or rewinding the magnetic tape at a faster speed than the normal playback speed, tracing across the inclined track by a rotating head, and reproducing a reproduced pilot signal from the inclined track. A magnetic recording/reproducing apparatus characterized in that the reference pilot signal is delayed at a predetermined timing, a pattern is read from the delayed reference pilot signal and the reproduced pilot signal, and a recording mode is detected from the pattern.