JPS6313191A - Magnetic tape and magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the sure retrieval operation by recording 1st and 2nd information index signals to a margin part when the 1st information has recorded and to a data part when the 1st information is not recorded. CONSTITUTION:A track formed obliquely onto a magnetic tape is divided into the 1st and 2nd parts. A pulse generating circuit 17 uses a position detection circuit 27 to detect the position of the marging part of the 2nd part from a reproducing signal of the PCM signal when the PCM audio signal is recorded to the 1st part, and uses a variable delay circuit 16 to detect the position of the data part of the 1st part when no PCM signal is recorded, thereby recording the index signal. Since the width of the erasure pulse is widen more than a conventional width, the old index signal is erased, and the missing of information is not caused. Thus, the sure retrieval is improved.

Description

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

[Conventional Technique #i] 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. .

However, such a search method using CTL signals requires a fixed head placed corresponding to the track on which the CTL signal is recorded and an additional circuit around it. #I video tape recorder, each track has tracking pilot signals f1, f2, f3, f4 (for example, 6.
5fH17,5fH,10,5fH,9,5f'H(f
H is the frequency of the horizontal fil signal)) is recorded and basically cannot be used in Hlif, which does not require a CTL signal. If adopted, a fixed head or the like, which is basically unnecessary, would have to be specially provided just for searching.

The frequency of the reproduction signal from the cue track is several tens of times higher during forward forwarding or rewinding than during normal recording and reproduction. It is extremely difficult to extract an index signal for each track by processing significantly changing frequencies, periods, waveforms, amplitudes, etc. Furthermore, since the cue track is located near the edge of the magnetic tape, it is easily damaged by the tape guide.

The inclined track of the 8 rttr video tape recorder is formed with a first part in which the first information is recorded and a second part in which the second information is recorded, and the first part is further configured to receive a clock signal. There is a section A where data such as PCM audio signals are recorded, a margin section C for after-recording, and an audio overlap section where the video signal of the previous field is continuously recorded. (Although it is divided into 1°, the present applicant previously proposed recording an index signal in this portion C. (Japanese Patent Application No. 60-27256).

[Problems to be solved by the invention] When recording an index signal during a playback operation, the playback P
Since a specific data position in the CM signal was detected and the position of the margin section C was generated from the detected signal, it was possible to record the index signal at a position with very little error relative to the margin section C. .

However, according to the 8#I video standard, the first portion, that is, the PCM signal, does not need to be recorded.

In other words, the minimum requirement is to record the frequency-modulated audio signal in the second portion, that is, the video signal portion, by superimposing it on the frequency-modulated video signal as well.

Now, when an index signal is recorded on a tape in which no PCM signal is recorded in the first portion, conventionally, a position corresponding to the margin portion C has been generated from a signal indicating the phase of the rotary head. That is, the index recording and erasing signals are generated by the output of the pulse generation circuit 17 that generates index recording pulses or erasing pulses that have a constant phase with respect to the head switching signal (H8WP) for switching the rotating head every 180 degrees. It was generating.

However, HS W P indicates the rotational phase of the rotary head mechanism, but it is generated by electrically adjusting and absorbing mechanical errors.
An error of less than a certain level, specifically, an error of ±1.5H or less is allowed according to the standard. (Note that H represents one horizontal scanning period.) Hereinafter, the problems of the conventional method will be explained with reference to FIG.

As shown in Figure 6 (1), if there is no error with respect to the absolute standard on the tape during both recording and playback, use the conventional method to
There was no problem even if index recording/erasing pulses were generated at fixed positions for 3WP. However, in Figure 6 (4
) When an index signal is recorded during playback with an apparatus having an error of <+1.5H, the index signal is recorded in part 1f of (5). This tape is then -1,5H
When reproduced by another device that has an error of , it is reproduced at timing (6). In this case, there is no problem in detecting the portion 11 and performing the search operation.

However, in this I[, the index recording and erasing pulses are at positions (7) and (8), so there is no problem in recording and reproducing part I2, but part 1 must be erased by the erasing operation. I couldn't do it.

Also, after recording the index signal in part I2, part 11 and part ! Since the index signal 2 is present on the tape, it may not be possible to determine which one to use during the search operation, making it impossible to perform the desired search.

Furthermore, when the PCM signal is after-recorded as in (9), part 2 is erased by recording the PCM signal, but part 11 remains.

In short, when tapes are used interchangeably between apparatuses, there are cases where the old index (No. 8) cannot be erased or the old index signal remains after PCM signal dubbing.

Therefore, it is conceivable to expand the erasing pulse width to a width that takes into account the positional change Vj width of the index signal, but in the case of an error conduit in the opposite direction to the above explanation, not only the video overlap portion d but also the video signal This results in an erasure period that extends to the end of the video signal, causing a missing period in the reproduced video signal and causing noise in the frequency-modulated audio signal as well.

[Object of the Invention] The present invention changes the index signal recording position when no PCM signal is recorded, so that when an index signal is recorded during playback by another device that has an error,
Alternatively, the purpose is to prevent incomplete index deletion during post-recording of PCM signals and to ensure reliability of search operations.

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

In the figure, reference numeral 11 denotes a rotating drum, in which a rotating magnetic head 81 for recording or reproducing (not shown) is mounted. 1
2 is a motor that rotates the rotating drum 11. Reference numerals 13 and 14 denote a frequency generator and a pulse generator, respectively, which output signals of a frequency and phase corresponding to the rotation of the rotary drum 11, and the outputs thereof 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 (H8WP signal @) for switching a plurality of rotating magnetic heads. This head switching signal is supplied to a pulse generation circuit 17 via a variable delay circuit 16 provided as necessary. The pulse generating circuit 17 outputs pulses that control the on/off states of the switches 18 and 19. Reference numeral 24 denotes a control device consisting of a microcomputer or the like, and is adapted to control on/off of the switches 20 and 21. 22 is a recording amplifier that amplifies the signal supplied to the rotating magnetic head for recording or reproducing =Illffl. 23 is an index circuit, which outputs an index signal to the recording amplifier 22 via switches 19, 20, and 21, and also outputs an index signal to the recording amplifier 22 through the switches 19, 20, and 21;
The index signal is detected from the reproduced signal. A position detection circuit 27 detects a predetermined position of the rotary head from a reproduction signal supplied from the rotary head.

[Operation 1 The operation will be explained with reference to FIGS. 2 to 6. The recording amplifier 22 receives video signals, audio (PC
~1) Signals to be recorded, such as signals and tracking pilot signals, are supplied from a video recording circuit, a PCM recording circuit, a tracking recording circuit, etc. (not shown), and these signals are recorded on a magnetic tape by a rotating magnetic head. recorded. 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 the state of the magnetic tape on which C3 is recorded in this way. That is, a track 2 is formed on the magnetic tape 1, which is inclined with respect to its longitudinal direction. , rotating drum 11 of magnetic tape 1
The winding angle is divided into a first part corresponding to about 36 degrees and a second part corresponding to about 185 degrees, and the front side has a PCM audio signal and a trunking pilot signal (TPS signal). The latter also contains an FM video signal and an FM video signal.
The M audio signal and the tracking pilot signal can each be recorded. 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 track 2 and in the negative direction on the other side, so that crosstalk from the adjacent I/rack is reduced. It's supposed to be. An audio I rack 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 areas provided between the information 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 reproducing switching position of the rotary magnetic head, and the vertical dosing signal is located at a distance e from there. The length of each of these parts is, for example, 525 lines as in the case of the NTSC system,
The settings are as shown in the table for a 6o field system and a 625 line, 50 field system as in the PAL system, for example.

(Hereinafter, blank space) In addition, in the following, 525 lines of NTSC system,
A case of a 60 field system will be explained. P
In the case of an AL type 62゛5 line, 5o field system, it can be determined in the same way.

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
It has a length of 3.0H in the case of the C system (3.6H in the case of the PAL system). The servo circuit 15 outputs a head switching signal from the output of the pulse light generator 14 corresponding to the rotation of the rotary drum 11 after a predetermined delay time of 1 w as necessary using, for example, a medium-stable multi-vibrator ( Second
Figure (1)). This signal is supplied to the pulse generation 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 has at least a first portion connected to a PC.
If the \1 audio signal is recorded, the position detection circuit 27 detects the demodulated signal of the PCM audio signal.
For example, the starting point can be detected using a signal obtained by decoding a synchronization signal indicating the start of data, a data block address, etc. as a timing reference, as shown in Figure 2 (5).
), the recording position of the index signal is generated in synchronization with this detection signal and the signal indicating the recording position of the index signal, and the switch 19 is turned on during this time. The width of the recording pulse is, for example, 1.5H (1.8H in the case of PAL system).
). In addition, it eliminates deletion omissions and
In order to prevent CM data from being erased, an erase pulse is generated and outputted with a length of 2.5H by extending the front and rear of the recording pulse by, for example, 0.5)-1, and the switch 18 is turned on during this period (Fig. 2). (7) dashed line). When an index recording operation is performed, the control tIII device 24 switches the switch 20
to the recording side and turn on 21, index circuit 2
3 to the recording amplifier 2 via switches 19.2o and 21.
2 (Fig. 2 (8)). This operation is performed over the period to be recorded (for example, ρj is 10 seconds). Therefore, track 2 where the index signal is recorded in part I
are formed in a predetermined number.

When erasing the index signal, the switch 21 is turned on and the switch 20 is also turned on to the erasing side.

A bias signal is therefore 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 the index recording signal.

Next, we will discuss the case where PCM (no. 8 is absent or at least the position detection signal is not output (undetectable) as shown in (10) in FIG. 2) in the first part.

Conventionally, recording/erasing pulses were generated at the positions shown in (6) and (7) using HS W P as a reference.
It had the disadvantage of incomplete erasure due to errors during compatibility.

Therefore, as shown in (11) in FIG. 2, the recording pulse is output at a earlier stage than in the past. For example, what used to be the 1.5H period from 5.3 days before HS W P,
The period is from 12H to 1.5H before W P. The erasing pulse is expanded forward and backward by 3H or more, 3.5 in this case, taking into account the index position @ error. In other words, the front 1 of H8WP
5.5H to 8°5H width.

The pulse generating circuit 17 can be configured to appropriately count lock pulses to obtain the required amount of delay. According to the example in FIG. 2, the delay time is first p c M (8
If a signal is recorded and its detection signal (5) is obtained at the start point of the data section, 45.2-5.3・39.9H between recording pulses (6) and erase pulse (7). up to 45.2-5.8・39.48. Next, PCM
(, When no.j is recorded, 1 field is 2.
62.5H, up to recording pulse (11), 2
62.5-12=250.50, erase pulse (12)
up to 262.5-15.5・247H. In this way, the pulse generation circuit 17 outputs the output of the position detection circuit 27 when a PCM audio signal is recorded, and
When a CM audio signal is not being recorded, the output of the variable delay circuit 16 is used as a timing reference to generate recording pulses and erasing pulses for controlling the on and off of switches 18 and 19, respectively.

The relationship between the recording pulse (recording area) and the erasing pulse (erasing area [) with respect to the absolute position on the magnetic tape when recording and reproducing the index signal when the position detection signal is not detected is shown in Figure 5. It becomes like this. Fifth
Figure (1) shows that the time axis error during index recording is divided by
1.5 days, which represents the worst case where the time axis error during playback is -1.5 days. In the worst case, the index recording pulse (2
) causes a shift of 3H, but since the erasing pulse width (3) has been expanded by more than 3H in the front and back than before, the old index signal can be erased without causing loss of video information. Furthermore, the position of the old index signal, including the old index signal, has been changed to be closer to the front than before, so the P
When the CM audio signal (4) is dubbed, the index signal is completely erased by the PCM recording signal even if there is a positional error, and there is no possibility that the old index signal remains even after dubbing.

On the other hand, at J5 during retrieval, 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 detects an index signal from the reproduction signal supplied from the rotating magnetic head via the preamplifier 25, and outputs the detection signal to the controller 611 device 24 when detected.

The index signal is less affected by head azimuth,
It is desirable to use a signal with as low a frequency as possible so that it can be easily detected even when fast forwarding or rewinding, but it is difficult to ensure a cancellation effect at low frequencies, so it is better to Setting the frequency to a suitable high value will bring about a good effect. For example, PCM
Color signal processing during data transfer and video input.
A signal of 2 to 3 MHz can be generated by appropriately dividing the frequency of the signal. Furthermore, the index detection circuit 23
Instead of providing a special PCM as an index signal, the PC1-1 reproducing circuit is shared, and the
It is also effective to set it so that it is related to the data cycle.

In this embodiment, the recording/reproducing head mounted on the rotating drum is used to erase the index signal. However, in a device equipped with a rotating head exclusively for erasing, the rotating erasing head is used to erase the index signal. Can be used for erasing.

The index signal is recorded by using the above-mentioned recording/reproducing radar, and the timing of the erasing pulse may be newly determined depending on the mounting position of the rotary erasing head.゛Please note that during these index recording/erasing sections during playback operation, normal playback signals cannot be obtained, so video @ and FM
It is preferable to apply pre-hold or mute processing to the audio signal.

In addition, in this embodiment, a position detection circuit is not required in a device that does not have a PCM circuit, and (11) and (
The pulse generation circuit only needs to generate timing 12).

Furthermore, in this embodiment, when the PCM signal is not recorded, the index position is set to the data section, but the index position may be set to the section a where a clock signal further in front is recorded.

[Effects] As described above, in the present invention, the trunk formed diagonally on the magnetic tape is divided into a first portion and a second portion, and the trunk is divided into a first portion and a second portion. When part A1 is not recorded, the index recording and erasing position is moved from the conventional margin part C for after recording to the data part in front, so the error in the index signal recorded first is reduced. Even if the combination is in the opposite direction, it can be erased reliably.

Moreover, even if it does not depend on the erasing operation, if PCM 4g is post-recorded later, the previously recorded index signal will be surely erased.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the magnetic recording and reproducing device of the present invention, and FIG.
Figure 5 shows the timing chart, and Figure 3 shows the timing chart.
FIG. 4 is a plan view of the MRT video tape, FIG. 4 is an enlarged plan view of its tracks, and FIG. 6 is a timing chart illustrating the conventional problems. 1...Magnetic tape 2...Track 3...Edge 4...Audio track 5.7...Guard track 6... ... Cue track 11 ... Rotating drum 12 ... Morph 13 ... Frequency generator 14 ... Pulse generator 15 ...
Servo circuit 16...Variable delay circuit 17...Pulse generation circuit 18, 19, 20.21...Switch 22...
... Recording amplifier 23 ... Index 0 24 ... Control device 25 ... Preamplifier 27 ... Position detection circuit Company Figure 3 Figure 4

Claims (2)

[Claims] (1) A magnetic tape on which information is recorded on tracks inclined with respect to its longitudinal direction by a rotating magnetic head,
The track has a first part where first information is recorded and a second part where second information is recorded, and at least the first part further includes a part a where a clock signal is recorded.
, a section b where data such as a PCM audio signal is recorded, a margin section c for after-recording, and a video overlap section d where the video signal of the immediately previous field is continuously recorded. When the first information is recorded, the index signal of the first information or the second information is recorded in the margin section c, and when the first information is not recorded, the index signal of the first information or the second information is recorded in the section b. A magnetic tape characterized by: (2) forming a first portion in which first information is recorded on a track inclined with respect to the longitudinal direction of the magnetic tape by a rotating magnetic head and a second portion in which second information is recorded; At least the first part further includes a part a where a clock signal is recorded, a part b where data such as a PCM audio signal is recorded, a margin part c for after-recording, and a video signal of the immediately previous field. When reproducing at least the first information, detecting the position of the margin section c from the reproduction signal of the first information, and detecting the position of the margin section c from the reproduction signal of the first information; an index signal of the first information or the second information, and when the first information cannot be obtained, the index signal of the first information or the second information is recorded from a signal generated corresponding to the rotational position of the rotary magnetic head. A magnetic recording/reproducing device characterized in that the position of portion b is detected and an index signal of the first information or the second information is recorded in the portion b.