JPS61162883A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain recording and erasing of an index signal without providing a fixed head specially by dividing tracks into the first part and the second part and recording an index signal at the boundary. CONSTITUTION:A pulse generating circuit 17 generates pulses of specified width (within 0.8H) when a specified time lapsed from generation of a head switching signal, and makes a switch 18 on during the while, and an index signal being inputted from an index circuit 23 through a switch 20 is supplied to a recording amplifier 22 through switches 18, 21. When retrieving, a magnetic tape on which the index signal is recorded is fed quickly or rewound as it is wound on a rotary drum 11. At such a time, the index circuit 23 detects the index signal from reproduced signals supplied from a rotary magnetic head through a pre- amplifier 25 and outputs the detected signal to a controlling device 19 when the signal is detected.

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.

[Conventional technology]

2. Description of the Related Art In magnetic recording and reproducing devices 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 consisting of 307 rectangular wave signals generally obtained from a pulse generator of a rotating drum may be 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. .

[Problem that the invention seeks to solve]

However, such a search method using the CTL signal requires a fixed head placed corresponding to the track on which the CTL signal is recorded and an additional circuit around it. A pilot signal for tracking is recorded on each track, such as a mm video tape recorder, and it basically cannot be used in devices that do 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. Also, when multiple indexes corresponding to one tilt (video) track are recorded on one cue track.

For example, special recording methods such as time division are required.

The equipment becomes complex and expensive. The frequency of the reproduction signal from the cue track is several tens of times higher during fast 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.

[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 mm video tape recorder.6 In the figure, 11 is a rotating drum; A rotating magnetic head (not shown) for recording or reproducing is mounted inside.

12 is a motor that rotates the rotating drum 11. 13
and 14 are a frequency generator and a pulse generator, respectively, which output signals of a frequency and phase corresponding to the rotation of the rotating 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 (H3WP 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 required. The pulse generating circuit 17 outputs pulses that control the on/off of the switch 18. Reference numeral 19 denotes a control device consisting of a microcomputer or the like, and is adapted to control on/off of switches 20 and 21. 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 the switch 2o and detects the index signal from the reproduction signal of the preamplifier 25. Reference numeral 26 denotes an oscillation circuit which is added as necessary, and is configured to supply an erasing current for the index signal to a rotating magnetic head for erasing (not shown). Further, the address detection circuit 27 generates a pulse at a predetermined timing from the reproduction signal output from the rotating magnetic head, and outputs it to the pulse generation circuit 17.

[Effect]

The operation thereof will be explained with reference to FIGS. 3 to 6. The recording amplifier 22 receives video signals, audio (PC
M) The signals to be recorded, such as signals, pilot signals, etc.
The 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 the magnetic tape by a rotating magnetic head. 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, which are 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 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 of width C is formed near the other edge 3.

Cue signals are recorded by a fixed head as required. 5 and 7 are guard tracks 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 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 1, for example, 525 lines as in the case of the NTSC system, and 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 a case where a plurality of parts corresponding to the first part are formed in the section 2 (part d can be considered to be included in the second part, but for convenience, it is 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 one part a to For example, a PCM audio signal, for example, is recorded in each of a total of six portions consisting of d.

Next, the recording and reproducing operation of the index signal will be explained. In the present invention, the index signal is recorded at the boundary (part d) between the first part and the second part of track 2. Part d has a length of 3.8H in the case of the NTSC system (4.5H in the case of the PAL system), and even excluding the tolerance of ±1°5H in the head switching position (±1.8H in the case of the PAL system). , 0.8H (0.9H in the case of PAL system) remains, so an index signal can be recorded in that partial work. The servo circuit 15 obtains a predetermined delay time as necessary by counting, for example, a predetermined clock pulse from the outputs of the frequency generator 13 and the pulse generator 14 corresponding to the rotation of the rotating drum 11,
A head switching signal is output (FIG. 6(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). 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, the pulse generation circuit 17 generates a signal of 260.2 (525x (180-2,62)/3
60+1.5)H has elapsed), that is, at the timing when the recording part of the index signal of part d arrives (Fig. 6(b)), a pulse of a predetermined width (within 0.8H) is output, and during that time the switch is Turn on 18 (Figure 6 (
Q)). Since the control device 19 turns on the switch 20.21 when the index recording operation is performed, the index signal (FIG. 6(d)) inputted from the index circuit 23 via the switch 20 is sent to the adder 24, for example. It is added to a bias signal of several MHz (FIG. 6(e)) and supplied to the recording amplifier 22 via the switch 18.21 (FIG. 6(f)). Such operations take place over the period of time to be recorded (for example, several seconds). Therefore, a predetermined number of tracks 2 on which index signals are recorded in partial sections are formed.

If, for example, a PCM audio signal is recorded on all of one track 2 as shown in FIG. It will be done. 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.

In the above operation, a signal to control the switch 18 is generated using the head switching signal as a timing reference, so there is no difference in the time axis error of the magnetic tape during recording and playback, or the information recorded on the first portion. It is inevitable that the timing will shift due to a time axis error with the information recorded in the second portion. Therefore, if a PCM audio signal is recorded in at least the first part,
The address detection circuit 27 decodes, for example, a data address, a data block address, etc. from the demodulated signal of the PCM audio signal to detect the starting point of part d (FIG. 6(g)), and an index signal is placed at the beginning of part d. (FIG. 6(h)) may be recorded. Therefore, in this case, the pulse generation circuit 17 uses the output of the address 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. It generates and outputs a pulse that controls the on/off state of the switch 18.

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 detected signal is output to the control device 19.

The index signal has a lower frequency than the low-pass conversion color signal, and each pilot signal f, , for tracking
f,, f3. f, (e.g. 102k) Iz, 117k
Hz, 1 in 149, 7 in 164) higher, 230
Can be any frequency signal below & below. When tracking is controlled using a piezoelectric element or the like in the holding portion of the rotating magnetic head, a predetermined pilot is installed in the portion C of the first portion of the track 2 in order to control the height of the plurality of rotating magnetic heads during recording. The signal f5 can be recorded, but in such a case, a signal having the same frequency as this pilot signal f may be used as the index signal. In this way, there is no need to prepare a special circuit for generating signals of different frequencies.

Also, the index signal may be, for example, its frequency, FM, A
A plurality of types can be provided by appropriately changing the modulation method such as M, the number of levels, etc., or a combination thereof. By doing this, for example, an index indicating the starting point of a predetermined program (in the case of a music signal, the starting point of a large division such as record, performer, genre, etc.) and a program milestone (the start of each song within a large division) can be displayed. point)
The index that indicates the index is differentiated (weighted), and there are multiple types of searches accordingly, such that when searching the former index, the latter index is ignored, and when searching the latter index, the former index is ignored. can also be searched. Such a configuration is especially desirable when recording and reproducing a long audio signal on one magnetic tape as in the case shown in FIG.

In the above description, the index signal is also recorded when a video signal or audio signal is recorded by the rotating magnetic head, but the index signal is also recorded when the rotating magnetic head is used to reproduce the video signal or audio signal. You can also do it. In this case, the leakage of the index signal will affect the weak playback signal output, so when supplying the index signal, the video signal and FM audio
It is best to mute the audio signal appropriately.

When erasing the index signal, it is sufficient to apply only the bias signal without applying the index signal. However, it is better to apply the erase current (bias current) for a slightly longer period of time before and after the recording position than during recording, and to increase its level slightly to increase the erase effect.

If there is a rotary magnetic head for erasing video or audio in addition to the rotary magnetic head for recording and reproducing, it is possible to use it to erase the index signal as well. The oscillation circuit 26 is a circuit for supplying an erasing current to the erasing rotary magnetic head in such a case.

For example, if the frequency of the index signal is 230kHz,
When the relative speed between the head and tape is 3.75 m/s, the recording wavelength is 16.3 μm, so if the width of the magnetic gap is set to about several microns, the index signal can be recorded by this rotating magnetic head for erasing. It is also possible to do so.

FIG. 2 is a block diagram in such a case. That is, the reproduction signal from the erasing rotary magnetic head is supplied from the preamplifier 32 to the index circuit 23, and the index signal from the index circuit 23 is supplied to the recording amplifier 31.
The data is supplied to the erasing rotary magnetic head via.

Furthermore, since the azimuth angle can be ignored, the rotary magnetic head for erasure can be used for recording and the rotary magnetic head for recording and reproducing can be used for reproduction, or vice versa.

〔effect〕

As described above, in the present invention, a track formed obliquely with respect to the longitudinal direction of a magnetic tape is divided into a first part for recording first information and a second part for recording second information. However, since the index signal is recorded at the boundary between the first part and the second part, it is possible to record and erase the index signal without installing a special fixed head, and the magnetic tape can be transferred to the rotating drum. You can search by fast forwarding or rewinding the file while it is being wound.

Furthermore, since the timing signal for the position at which the index signal is recorded and reproduced is generated using the first information signal as a reference, it is less affected by time axis errors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the magnetic recording/reproducing apparatus of the present invention, and FIG.
The figure is a block diagram of another embodiment, and Figure 3 is 8III.
11 is a plan view of the videotape, FIGS. 4 and 5 are enlarged plan views of its tracks, and FIG. 6 is a timing chart. 1... Magnetic tape 2... Track 3... Edge 4... Audio track 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 generation circuit 19...Control device 22.
31... Recording amplifier 23... Index circuit 24... Adder 25.
32... Preamplifier 26... Oscillation circuit and above Figure 2

Claims (1)

[Claims] (1) In a magnetic recording and reproducing device that uses a rotating magnetic head to record information on a track that is inclined with respect to the longitudinal direction of a magnetic tape, the track is a first track on which first information is recorded.
and a second part in which second information is recorded, a boundary part is provided between the first part and the second part, and the first information is recorded in the boundary part. A magnetic recording and reproducing apparatus that records an index signal, performs a search operation using the index signal, and generates a timing signal for a recording/reproducing position of the index signal from the first information signal.