JPS63177386A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To easily and securely detect an index signal by constituting a titled device in such a way that the detected index signal is held for a prescribed time when a rotary magnetic head retrieves the position of a magnetic tape. CONSTITUTION:The the time of retrieval, the magnetic tape in which the index signal is recorded is fast feeded or rewound while it is wound to a rotary drum 11. At such a time, an index circuit 23 detects the index signal from a reproduced signal supplied from the rotary magnetic head through a pre-amplifier 25, and the signal is transmitted to a holding circuit 28 when it is detected. The circuit 28 holds the signal level for a prescribed length of time, and a control circuit 19 retrieves the position of preceding and subsequent magnetic tapes by N (N=1,2...) with using the signal which has been held. If the control circuit 19 generally holds the index signal in the circuit 28 sufficiently prior to the edge of a head switching HSWP signal, the presence and absence of the index signal can be checked after the processing of high priority is completed in the device 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing apparatus for recording and reproducing information using a rotating magnetic head such as a video tape recorder.

[Prior Art] In magnetic recording and reproducing apparatuses such as video tape recorders, a tape counter is sometimes used to search for a predetermined recording or reproducing position. However, searching using a tape counter has the drawback of lacking accuracy. Therefore, a control signal (CTL signal) for tracking control, which is generally a 30 Hz rectangular wave signal obtained from a pulse generator of a rotating drum, is sometimes used for the search. Since the CTL signal only uses the timing of one edge for tracking, a signal with a changed duty can be used as a cue signal (cue signal or index signal) for position search. be.

However, such a search method using CTL (No. 8) requires a fixed head placed corresponding to the track on which the CTL signal is recorded and a peripheral circuit around it. Like the so-called 81NIt video tape recorder, each track is provided with tracking pilot signals fj, f2°fa, fa (for example, 6.5 fs and 7.5 fs, respectively).

10.5fH, 9.5fH (fs is the frequency of the horizontal synchronizing signal) are recorded, and basically cannot be used in the H position where a CTL signal is not required. If adopted, a fixed head or the like, which is basically unnecessary, would have to be specially provided just for searching. You can also set multiple indexes corresponding to one tilt (video) track to one
When recording on the cue track of a book, a special recording method such as time division is required, resulting in multiple and expensive devices. And the frequency of the playback signal from the cue track is
When fast forwarding or rewinding, the I
This is several tens of times more than when you put 5. It is extremely difficult to process significantly changing frequencies, periods, waveforms, vibrations, etc. and extract index signals for each rack. Furthermore, since the cue track is located near the edge of the magnetic tape, it has the disadvantage that it is easily susceptible to Jul by the tape guide. 8t
The inclined track of the rtrr video tape recorder is formed with a first part in which first information is recorded and a second part in which second information is recorded, and the first part is further connected to a clock signal. There is a recorded part a, a part where data such as a PCM audio signal is recorded, a margin part C for after-recording, and a video overlap part d where the video signal of the immediately previous field is continuously recorded. It is divided into.

The present applicant previously proposed recording an index signal in this portion d or margin portion C (Japanese Patent Application No. 59-2
77972, patent application No. 60-27256, [[60-40
892, Japanese Patent Application No. 60-107954>.

[Problem to be solved by the invention J However, the area of the index signal in the 8M video tape recorder is 1 to 2H<H is the horizontal scanning period)
It is a very short period of time.

Furthermore, since the index signal area is usually located at the boundary between the first and second parts of the track, it is a transition point between the first and second information, and there are many signals that need to be controlled and processed. M is rough. Therefore, the I? of the magnetic recording/reproducing device?
When the ilJ control device is configured using a microcomputer or the like, there is a drawback that it is difficult to detect a short index signal as described above.

[Objective of the Invention 1] The present invention has been made to eliminate the above-mentioned drawbacks, and provides a magnetic recording/reproducing device capable of easily and reliably detecting an index signal and searching the position of a magnetic tape. It is intended for this purpose.

[Means for Solving the Problems] FIG. 1 shows a block diagram when the magnetic recording/reproducing device of the present invention is applied to an 8M video tape recorder.

In the figure, reference numeral 17 denotes a rotating drum, into which a rotating magnetic head (not shown) for recording or reproducing is mounted. 1
2 is a motor that rotates the rotating drum 17. , 73
and 14 are a frequency generator and a pulse generator, respectively, which output signals having a frequency different from that corresponding to the rotation of the rotary drum 11, and their outputs are supplied to a servo circuit 15. The servo circuit 15 outputs a rotation control signal to the motor 12 and also outputs a head switching signal @ (1-18WP signal) for switching a plurality of rotating magnetic heads. This head switching signal has a variable delay provided as necessary. Mouth M1
6 to the pulse generation circuit 17. Pulse ordering circuit 77 outputs pulses that control turning on and off of switch 18.26. 19 is a control wJ device consisting of a microcomputer, etc., which turns on and off switches 20 and 21! ! ilJ'a. 22 is a recording amplifier that amplifies a signal supplied to a rotating magnetic head for recording or reproducing information. 23 is an index circuit which outputs an index signal to the adder 24 via switches 26 and 20 and detects the index signal from the reproduction signal of the preamplifier 25. A position detection circuit 27 detects a predetermined position of the rotary head from a reproduction signal supplied from the rotary head. 28 is a holding circuit that holds the signal detected by the index circuit 23 for a certain period of time.

[Function] The function will be explained with reference to FIGS. 2 to 7. The recording amplifier 22 receives video signals, audio (PC
M) Signals to be recorded, such as signals and tracking pilot signals, are supplied from a video signal circuit, a PCM recording circuit, a tracking recording circuit, etc. (not shown), and these signals are recorded on the magnetic tape by a rotating magnetic head. be done. During this time, the servo circuit 15 compares the signals from the frequency generator 13 and the pulse generator 14 with a reference signal, and controls the rotation of the motor 12 in response to the error signal.

During reproduction, a reproduction signal from the rotating magnetic head is amplified by a preamplifier 25 and supplied to a video reproduction circuit, a PCM reproduction circuit, a tracking circuit, etc.

FIG. 3 shows how signals are recorded on the magnetic tape in this manner. That is, tracks 2 are formed on the magnetic tape 1 so as to be inclined with respect to its longitudinal direction. For convenience, the track 2 includes a first part corresponding to a winding angle of about 36 degrees of the magnetic tape 1 with respect to the rotating drum 11, and a first part corresponding to a winding angle of about 18 degrees.
a second part corresponding to the fifth, and the former has a PC
M audio signal and tracking pilot signal (T
PS signal), and the latter can record an FM video signal, an FM audio signal, and a tracking pilot signal. The azimuth angle of the corresponding rotating magnetic head is inclined by about 10 degrees in the positive direction on one side of the adjacent tracks 2 and in the negative direction on the other side, so that crosstalk from the adjacent tracks is reduced. It has become. An audio trunk 4 having a width R is formed near one edge 3, and a normal analog audio signal can be recorded by a fixed head if necessary. A cue track having a width C is formed near the other edge 3, and a cue signal is recorded by a fixed head as necessary. 5 and 7 are guard tracks provided between the news recording track and the control signal recording track.

FIG. 4 shows one track 2 on an enlarged scale. That is, the first part further includes a part a where a clock signal is recorded, a part where data such as a PCM audio signal is recorded, and a margin part C for after-recording.
and a video overlap section d where the video signal of the immediately previous field is continuously recorded.

The end position of the portion d is the switching position of the rotary magnetic head, and the vertical synchronizing signal is located at a position separated by a distance e from there. The length of each of these parts is, for example, 525 lines or 6 lines as in the case of the NTSC system.
The settings are as shown in the table for a 0 field system and, for example, a 625 line, 50 field system as in the PAL system.

Table 5 shows multiple parts corresponding to the first part ff! I second
(The part d can be considered to be included in the second part, but for convenience, it is considered to be included in the first part.) In other words, the length of the first part is an integral multiple of approximately five times the length of the second part, and five parts corresponding to the first part are formed in the second part, and part a For example, a PCM audio signal, for example, is recorded in each of six parts in total consisting of d to d.

Next, the recording and reproducing operation of the index signal will be explained. In the present invention, the index signal is recorded in the margin section C of the first section of the track 2. Part C is NTS
For C method 3. 3.6H for OHCPAL method)
It has a length of The servo circuit 15 obtains a predetermined delay time as necessary by counting predetermined clock pulses from the outputs of the frequency generator 13 and the pulse generator 14 corresponding to the rotation of the rotating drum 11, and switches the head. A signal is output (FIG. 2(a)). This signal is supplied to the pulse generating circuit 17 via the variable delay circuit 16 (the variable delay circuit 16 is not necessarily required if the track configuration is as shown in FIGS. 3 and 4). The pulse generating circuit 17 generates a signal when a predetermined period of time has elapsed since the generation of the head switching signal (for example, in the case of the NTSC system, 256.
7 (262,5-3,8-3,0+1.0)H has elapsed), that is, at the timing when the recorded portion I of the index signal of portion C arrives (Fig. 2(b)).
, a recording pulse of a predetermined value (for example, 1.58) is output, and the switch 26 is turned on during this period (solid line in FIG. 2(C)).

In addition, in order to eliminate omissions and to prevent PCM data from being erased, record data so that the end of the part C is separated from the end of the part C by 0.5 days, for example, and the end coincides with the end of part C. An erasing pulse is generated and outputted by extending the front and back of the pulse by 0.5H, for example, to a length of 2.5H, and during this time the switch 18 is turned on (as shown by the broken line in FIG. 2(C)).

When an index recording operation is performed, the control 11 device 1
9 turns on the switch 20.21, the index signal inputted from the index circuit 23 via the switch 26.20 (FIG. 2(d)) is converted into a bias signal of, for example, several MHz in the adder 24. Figure 2 (e))
is added to the recording amplifier 2 via switches 18 and 21.
2 (FIG. 2(f)). Such actions take place over the period of time to be recorded (for example, several seconds). Therefore, a predetermined number of troughs 2 are formed in which the index signal is recorded in the portion (2).

If, for example, a PCM audio signal is recorded on all of one track 2 as shown in FIG. 5, the variable delay circuit 16 is turned on in six sections I of one track 2. is provided. In this case as well, since the basic timing is the same as in the cases shown in FIGS. 3 and 4, there is no need to provide any special circuit other than the variable delay circuit 16.

When erasing the index signal, the switch 21 is turned on, and the switch 18 is also turned on by the erasing pulse. Therefore, only the bias signal is supplied to the rotating magnetic head. In this case, the erasing effect can be enhanced by setting the bias signal at a higher level than during recording.

Regarding the above operation, the head switching signal is used as a timing reference to generate a signal to control the switches 18 and 26, so there is no error in the recording position on the magnetic tape during recording and playback, or when recording in the first part. It is inevitable that the timing will shift due to a time axis error between the ``counterfeit information'' and the information recorded in the second part. Therefore, if the PCNt-dio signal is recorded in at least the first part, the position detection circuit 27 decodes, for example, a synchronization signal indicating the start of data, a data block address, etc. from the demodulated signal of the PCM audio signal. Using the obtained signal as a timing reference, the starting point of section C or the end point of section C, etc. is detected (Fig. 2 (Q)), and in synchronization with this detection signal, a signal indicating the recording position of the index signal is output. You can also try cheating. Therefore, in this case, the pulse generation circuit 17 uses the output of the position detection circuit 27 when a PCM audio signal is recorded, and the output of the variable delay circuit 16 when a PCM audio signal is not recorded, as a timing reference. as switch 18.26
A recording pulse and an erasing pulse are respectively generated to control the on/off state.

When an index signal is recorded and reproduced in the margin section C in this way, the relationship between the position detection signal, recording pulse (recording area), and erasing pulse (erasing area) with respect to the absolute position on the magnetic tape is as shown in FIG. become. Figure 6(a) shows the case where there is no time axis error during recording.
Figure (b) shows the case where there is no time axis error during playback, and Figure 6 (C) shows the case where the time axis error during recording is +1°5H and the time axis error during playback is -1.5 days. Each represents the case of fi evil. It can be seen that even in the worst case, the length of the video overlap portion d is approximately 0°8H.

On the other hand, as in the past, for example, the overlap part d
When recording an index signal at the beginning of , if there is no time axis error, as shown in FIG.
If a time axis error of -1.5H occurs during playback, see Figure 7 (
In b), when a time axis error of -1.5H during recording and +1.5H during reproduction occurs, the results are as shown in FIG. 7(C).

That is, as shown in FIG. 7(b), when recording +1°5H,
In the worst case where a time axis error of -1.5H occurs during playback,
The length of the video overlap part d is approximately 0.8 days,
If we were to record the index signal over a length of 0.8H, there would be no room at all, so if the main 1°5H
If a time axis error exceeding the standard (±1.8H in the case of PAL system) occurs, part of the video signal will be lost. Furthermore, if a margin is to be provided, the length of the index signal recording section I must be shortened to 0.8) (or less).

On the other hand, during a search, the magnetic tape 1 on which the index signal is recorded is fast-forwarded or rewound while being wound around the rotating drum 11. At this time, the index circuit 23
The index signal is detected from the reproduction signal supplied from the rotating magnetic head via the preamplifier 25, and when detected, the detection signal is sent to the holding circuit 28. Holding circuit 2
8 is.

The signal level is held for a certain period of time (for example, a time sufficient for the control unit 19 to process the signal), and using this held signal, the control device 19 outputs ±N (N=1.2...
...) to search for the previous or next position on the magnetic tape. In FIG. 2, the position of the index signal is immediately before the head switching signal (H3WP signal), but normally the control I device 19 concentrates signal processing near the edge of the H8WP signal, so If the index signal is held in the optical holding circuit 28,
After the high-priority processing is completed in the control wJ device 19, the presence or absence of the index signal can be checked. In order to detect the index signal, the gate extracts only the reproduced signal in the vicinity of the index signal recording area I of part C, and is synchronized with the output of the position detection circuit 27 and sufficiently includes fluctuations during high-speed tape running. Pulses with such a wide width may be generated and used.

The index signal is less affected by head azimuth,
It is desirable to use a signal with a frequency as low as possible so that it can be easily detected even during fast forwarding or rewinding. However, in part C, the standard allows a high-level pilot signal f5 to be recorded at a frequency of 230 kHz or less.

This pilot signal f5 is used to control the height of a plurality of rotary magnetic heads during recording in the holding portion of the rotary magnetic heads. Therefore, the index signal is 2
Higher than 30kHz2, the pilot signal can sufficiently separate the frequency from 5, approximately 740kHz±50. It is possible to use a signal with a frequency that can be frequency separated from the low frequency conversion color signal of OkHz.

For example, if the frequency of the index signal is made sufficiently higher than the frequency of the FM audio carrier, 1.5 MHz,
Separate detection is easily possible.

In addition to recording or erasing an index signal when recording a video signal or an audio signal using a rotating magnetic head, it is also possible to record an index signal when reproducing a video signal or an audio signal using a rotating magnetic head. can. In this case, since the leakage power of the index signal affects the weak reproduced signal output, it is preferable to appropriately mute the video signal and the FM audio signal when supplying the index signal.

[Effect 1 As described above, in the present invention, an index signal of information is recorded on a track by a rotating magnetic head, and when searching for a position on a magnetic tape, the detected index signal is held by a holding circuit for a certain period of time. This makes it easier to process and control signals by the control device of the magnetic recording and reproducing device.
A microcomputer or the like can be used as a device at a lower cost.

Furthermore, by setting the holding time of the holding circuit to an appropriate time, even when tracks are formed as shown in FIG. 5, index signals corresponding to each of the six portions can be easily processed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the magnetic recording/reproducing apparatus of the present invention, and FIG.
Figure 6 and Figure 6 are the timing charts, Figure 3 is 8M
A plan view of the video tape, FIGS. 4 and 5 are enlarged plan views of its tracks, and FIG. 7 is a timing diagram of a conventional apparatus. 1...Magnetic tape 2...Track 3...Edge 4...Audio 1st to rack 5.7...Guard track 6. ...Cue track 11 ... Rotating drum 12 ... Motor 13 ... Frequency generator 14 ... Pulse generator 15 ...・
Servo circuit 16...Variable delay circuit 17...Pulse generating circuit 18.26...Switch 19...W control device 22...Recording Amplifier 23... Index circuit 24.
... Adder 25 ... Preamplifier 27
...Position detection circuit 28...Holding circuit patent application: Pioneer Co., Ltd.

Claims (1)

[Scope of Claims] A device for recording and reproducing information by forming a track inclined with respect to the longitudinal direction of a magnetic tape using a rotating magnetic head, wherein the track includes a first track on which first information is recorded. forming a second part, a second part in which second information is recorded, and a third part in which an index signal of the first information or the second information is recorded, and detecting the index signal. What is claimed is: 1. A magnetic recording and reproducing apparatus comprising: a detecting section; and a holding means for holding an output signal of the detecting section for a certain period of time; and searching for the position of the magnetic tape based on the output signal from the holding means.