JPS6228903A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To make operation secure by controlling the recording and erasure of an index according to the difference between the time which is a certain time after the position where the recording position of the 1st information is detected and the time when a reference signal is generated for the rotational position of a rotary magnetic head by detecting the time difference. CONSTITUTION:Signals which have a frequency and a phase corresponding to the rotation of a rotary drum 11 are outputted from the frequency generator 13 and pulse generator 14 of a magnetic recording and reproducing device and supplied to a servo circuit 15, thereby supplying head switching pulses to a processing circuit 28. Further, a controller 19 outputs signals for controlling respective parts and a pulse generating circuit 17 controls switches 18 and 20. Further, an index detecting circuit 24 detects index signals of the 1st and the 2nd information parts through a preamplifier 25. Then, the time difference between the time which is the certain time after the position where the 1st information recording position is detected and the time when the reference signal is generated for the rotational position of the rotary magnetic head is detected by the controller 19 to control the recording and erasure of the index signal according to the time difference.

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.

- [Summary of the Invention] The present invention records or reproduces first information on a first portion of a track inclined with respect to the longitudinal direction of a magnetic tape, and records or reproduces first information on a second portion of a track, using a rotating magnetic head. In a magnetic recording and reproducing device that records or reproduces the first information or the second information and also records or erases an index signal of the first information or the second information at a predetermined position of the first portion, the first detecting a recording position of information; detecting a time difference between a predetermined time after a certain period of time from the detected recording position and a time at which a reference signal is generated corresponding to one rotational position of the rotating magnetic head;
The index signal is recorded or erased at a timing corresponding to the detected time difference, and when the index signal is recorded or erased on the first part of the magnetic tape on which the first information has already been recorded, the recording Alternatively, the erasing position is always set at a predetermined position.

[Conventional technology]

The 8m video tape recorder is tilted from 1 to 30 meters.
A first part in which first information is recorded and a second part in which second information is recorded are formed, and the first part further includes a part a in which a clock signal is recorded, a PCM audio signal, etc. The area in which data is recorded is divided into a margin area C for after-recording and a video overlap area d in which the video signal of the immediately preceding field 1- is continuously recorded. previously proposed recording an index signal consisting of a signal of a predetermined frequency in this margin section 0 or video overlap section d (
Japanese Patent Application No. 59-277972, Japanese Patent Application No. 60-2464, Japanese Patent Application No. 60-27256, Japanese Patent Application No. 1987-10795
No. 4, etc.).

In such a previous proposal, for example, a margin section C on a magnetic tape in which first information is already recorded in the first section.
and record the index signal in the video overlap area d (
or erase), the head switching pulse (H8
WP) to detect the position where the Intex signal is recorded.

For example, - shows the position of each part relative to the absolute position when recording and reproducing an Intex signal in the margin part C, recording pulse ■ (recording area), erasing pulse E (erasing area)
In an ideal case where there is no time axis error during recording, the relationships are as shown in FIGS. 3(a), 3(b), and 3(c), respectively. On the other hand, a time axis error of 1.58 (H is one period of a horizontal scanning line) in the delay direction (standard - 1 - allowed)
If the first information is recorded under certain conditions, magnetic tape -
The positions of each part of 1- are shown in FIG. 3(d). As shown in FIG. 3(e), this magnetic tape l- has a 1.5I
] When recording the information (after recording) in the advanced state (permitted by the standard), the information shown in Figure 3 (f
). That is, the new data b' and the index signal ■' of the margin section C' are recorded at a position 3TT ahead of the already recorded index signal of the margin section C'. Such a situation in which the original index signal (2) remains without being erased occurs even under the worst-case conditions as described above, when new information shifts in the advancing direction.

[Problem that the invention seeks to solve]

If two index signals are recorded in such close positions, the original index signal will also be detected during a search, and there is a risk of malfunction. Even if the detection position is limited based on the signal generated from the data address etc.
When the traveling speed of the magnetic tape is increased during a search, the detection of data addresses becomes unstable and various fluctuations occur, making it difficult to detect only new intex signals.

Furthermore, when a new index signal is recorded, it becomes difficult to erase the original index signal. That is, as shown in FIG. 3(g), the position (occurrence timing) of the erase pulse E is set based on the data address in the same way as during recording, so the erase pulse E corresponds to the position of the new index signal. Therefore, as shown in FIG. 3(h), only the new index signal can be erased.

[Means for solving problems]

FIG. 1 shows a block diagram when the magnetic recording/reproducing apparatus of the present invention is applied to an 8-speech video tape recorder.

In the figure, reference numeral 11 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 11. ] 3 and 14 are a frequency generator and a pulse generator, respectively, which output signals with 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 pulse (nsWP) for switching a plurality of rotating magnetic heads. This head switching pulse is supplied to the processing circuit 28 via a variable delay circuit 1-6 provided as necessary. Processing circuit 2
8 outputs this head switching pulse to each circuit as it is except when the first information has already been recorded. 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 signal generation circuit which outputs an index signal to the recording amplifier 22 via a switch 20.18.

Further, 24 is an index signal detection circuit, which detects an index signal from the reproduction signal of the preamplifier 25. An oscillation circuit 26 generates a reference signal of a predetermined frequency and outputs it to the index signal generation circuit 23. A position detection circuit 27 detects a predetermined position of the rotary head from a reproduction signal supplied from the rotary head.

[Effect]

The operation will be explained with reference to FIG.

The recording amplifier 22 receives signals to be recorded such as a video signal, a PCM audio signal, an FM audio signal, and a tracking pilot signal.
The signals are supplied from an M circuit, an FM audio circuit, a tracking circuit, etc., and these signals are recorded on a 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 playback, the playback signal from the rotating magnetic head is amplified by the preamplifier 25 and sent to the video circuit, PCM circuit,
It is supplied to the FM audio circuit, tracking circuit, etc.

On the magnetic tape on which signals are recorded in this manner, tracks are formed that are inclined with respect to the longitudinal direction of the magnetic tape. For convenience, the track is divided into a first part corresponding to a winding angle of about 36 degrees with respect to the rotating drum 11 of the magnetic tape, and a second part corresponding to a winding angle of about 185 degrees. In the latter case, an FM video signal, an FM audio signal, and a tracking pilot signal can be multiplexed and 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 and in the negative direction on the other side, so that crosstalk from the adjacent track is reduced. ing.

A plurality of parts corresponding to the first part can be formed in the second 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
It is also possible to record, for example, a PCM audio signal in each of the 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 the first
It is recorded in the margin part C or the overlap part d of the part. In the following, the case of recording in the margin section C will be explained. Margin part C is 3.0 in case of NTSC system.
It has a length of H (3.6H in case of FAT method). The servo circuit 15 obtains a predetermined delay time as necessary by counting predetermined clock pulses, for example, from the outputs of the frequency generator 13 and the pulse generator 14 corresponding to the rotation of the rotating drum 11, and performs head switching. Outputs pulses. This signal is supplied to the processing circuit 28 via the variable delay circuit 16 (the variable delay circuit 16 is not necessarily required if a plurality of first parts are not formed in the second part).

If the first information is not yet recorded on the magnetic tape, the processing circuit 28 processes the first information from the position detection circuit 27.
When the detection signal (FIG. 2(b)) corresponding to the start position of the margin section C (or the end position of the data section) is not output, the head switching pulse is output as is to each circuit.

The pulse generating circuit 17 generates a pulse of a predetermined width (for example, 1.5H) when a predetermined period of time has elapsed since the generation of the head switching pulse, that is, at the timing when the recorded portion (2) of the index signal in the margin section C arrives (see FIG. 2(a)). The recording pulse is outputted, and the switch 18 is turned on during this period.

When the index recording operation is performed manually or automatically, the control device 19 activates the pulse generation circuit 17 and turns on the switch 20 for a predetermined period of time (for example, 10 seconds) required to reproduce and detect the index signal. Since it is turned on, the index signal output from the index signal generation circuit 23 is supplied to the recording amplifier 22 via the switch 20.18. This operation is performed for a predetermined time (1,0 seconds) required for reproducing and detecting the index signal, so that the number of tracks in which the index signal is recorded in section 2 is equal to the predetermined number (for reproducing and detecting the index signal). (number of pieces required) is formed. At this time, no bias signal is supplied to the recording amplifier 22, and the index signal is recorded in saturation on the magnetic tape. In this way, by recording the index signal at the highest possible level of saturation so as to obtain the maximum playback output, when detecting the index signal, it is possible to distinguish it from other signals other than the index signal such as FM video signal. The detection level of the index signal can be easily set, and the detection accuracy of the index signal can be improved.

For example, when a PCM audio signal is recorded on all of one track, the variable delay circuit 1 is set so that the switch 18 is turned on in six parts of one track.
6 is provided. In this case as well, since the basic timing is the same as in the case described above, there is no need to provide any special circuit other than the variable delay circuit 16.

When commanded to erase the index signal, the control device 19
As in the case described above, the pulse generating circuit 17 is activated to output an erasing pulse of a predetermined width at the timing when the recorded portion (2) of the index signal of the margin section C arrives, and the switch 1B is turned on during this period. The width of the erase pulse can be made equal to the width of the recording pulse, but in order to eliminate omission of erase and to prevent PCM data from being erased, the width of the erase pulse is set at a distance of, for example, 0.5 mm from the end of the data area.
It is preferable to extend the front and rear of the recording pulse by, for example, 0.5IT so that the length of the recording pulse is 2.5I-(2,5I-()) so that the end of the recording pulse coincides with the end of the margin section C. When the signal is generated, the control device 19 turns on the switch 21 for a time equal to or slightly longer than the time for turning on the switch 20 (10 seconds).Therefore, the predetermined frequency higher than the index signal generated by the oscillation circuit 26 is erased. The signal is passed through switch 21.18 to recording amplifier 22.
provided and recorded. In this case as well, no bias signal is supplied to the recording amplifier 22, but when the erase signal is set to a level corresponding to the optimum recording current, the erase signal is recorded in saturation and the index signal is erased. Of course, if the level of the erasing signal is set higher than this level, the erasing effect of the index signal will be further improved.

In the above operation, the signal for controlling the switch 18 is generated using the head switching pulse that is not processed by the processing circuit 28 as a timing reference. It is unavoidable that the timings of the information recorded in the second part and the information recorded in the second part deviate due to a time axis error. Therefore, the above operation is performed when the first information has not yet been recorded on the magnetic tape.

If the first information has already been recorded on the magnetic tape-1, the operation is as follows. For example, when a video signal is recorded in the second part and a corresponding PCM audio signal is already recorded in the first part, when after-recording a new PCM audio signal in the first part, the first It is necessary to maintain the linearity of the track formed by the first part and the second part. Therefore, even if the first part of the track is in the recording mode, the second part is in the playback mode and tracking servo is applied. Immediately after receiving the command to start the after-recording operation, the control device 19 causes the magnetic tape to run in the playback mode for a short period of time (several seconds at most).

During this start-up period, the control device 19 determines whether or not the 1-th information is recorded in the first portion. In other words, when a PCM audio signal is recorded in the first part, the position detection circuit 27 decodes, for example, a synchronization signal indicating the start of data, an arbitrarily determined specific data block address, etc. from the demodulated signal of the PCM audio signal. Using the signal obtained as a timing reference, the starting point of the margin section C or before the end of the data section is detected (FIG. 2(b)). The processing circuit 28 outputs the head switching pulse (FIG. 2(C)) output from the variable delay circuit 16 as it is to each circuit during the racing period, while
When a certain period of time T□ has elapsed after the detection signal is output from the position detection circuit 27 (the original time from when the detection signal is output until the head switching pulse is generated in the case where there is no time axis error). The time difference T2 between the time and the time when the head switching pulse (H8WP') is output from the variable delay circuit 16 is measured.

When the start-up period ends and the tracking becomes stable, the controller [19] switches the device from the playback mode to the record mode, issues a control signal to the processing circuit 28, and outputs the head switching pulse (H8WP') from the variable delay circuit 16.
) is delayed by time T2 and output as the final head switching pulse (H8WP) (Fig. 2(d)
). During this time T2, the value of the previous field is used for the next field, and the values are updated sequentially. Based on the relationship between the original data and the head switching pulse (H8WP'), if the head switching pulse (H8WP) needs to be output before the head switching pulse (H8WP'), the head switching pulse (H8WP') must be output before the head switching pulse (H8WP').
) is delayed by approximately one field. This head switching pulse (H8WP) is supplied to each circuit as a reference signal, so the newly recorded data section b'' and margin section c
The timing at which the index signal I'' (Fig. 2(e)) is generated and supplied is the same as the timing at which the index signal I'' (Fig. 2(e)) is generated and supplied.
Matches the position in a)). Therefore, a new index signal will be recorded on top of the original index signal, and the original index signal will not be erased and remain (
Figure 2(f)).

Similarly, when erasing the index signal, the switch 18 is turned on and off based on the detection signal of the position detection circuit 27.
An erase pulse is generated to control the off.

Therefore, the pulse generation circuit] 7 outputs the output of the position detection circuit 27 when a PCM audio signal is recorded, and the head switching pulse output from the processing circuit 28 when a PCM audio signal is not recorded. A recording pulse and an erasing pulse are respectively generated as reference signals for controlling on/off of the switch 18.

On the other hand, during a search, the magnetic tape 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 detection circuit 24 detects the index signal from the reproduction signal supplied from the rotating magnetic head via the preamplifier 25, and outputs the detection signal to the control device 19 when detected. In order to detect the index signal, a signal for gate-extracting only the reproduced signal in the vicinity of the index signal recording area (2) of the margin section C is synchronized with the output of the position detection circuit 27, and sufficiently absorbs fluctuations during high-speed tape running. It is also possible to generate and use pulses with wider widths, including:

Incidentally, it is desirable that the index signal has a frequency as low as possible in order to reduce the influence of head azimuth and to facilitate detection even during fast forwarding or rewinding. However, in the margin part C, 230 kH
The standard stipulates that a high level pilot signal f5 is recorded at a frequency below z. This pilot signal f6 is used to control the height of a plurality of rotating magnetic heads during recording when a piezoelectric element or the like is used in the holding portion of the rotating magnetic head for tracking control.

The index signal is then higher than 230 kHz,
It is desirable that the signal has a frequency that can be sufficiently separated in frequency from the pilot signal f5 and also from the low-frequency conversion color signal of about 740 kHz±50'0 kHz.

For example, if the frequency of the index signal is approximately 1.2 MHz, the frequency (FM) of the FM audio carrier that is frequency (FM) modulated by the audio signal and multiplexed on the second portion of the inclined track is 1.2 MHz. , 5M Ilz are sufficiently separated and can be easily separated and detected. However, when the frequency of signals recorded on a magnetic tape is low, the erasing effect is reduced. If the index signal remains without being completely erased, erroneous operations will occur during retrieval. Therefore, the index signal is selected to have a higher frequency than the FM audio carrier.

On the other hand, as mentioned above, the frequency of the index signal needs to be lower than the frequency of its cancellation signal. Also, from a practical standpoint, it is not a good idea to provide many oscillators inside the device. Therefore, for example, a signal that is used as a reference signal in a frequency conversion circuit (not shown) that converts a color signal to a low frequency during recording is used as an erasure signal, and it is
A signal frequency-divided by 3 can be used as an index signal. The frequency of such a reference signal is 37 in the case of the NTSC system.
8 fH (f++ is 15.734 kHz), 375 ft1 (fs is 15,625 kHz) for PAL system
), the index signal is N T SC
1,983MHz for PAL system, 1.9 for PAL system
53 MHz. In this way, the reference signal that the oscillation circuit 26 originally outputs for the frequency conversion circuit can be used as an erasure signal as is, and the index signal generation circuit 23 can easily divide the frequency into 1/3. An index signal can be generated.

Furthermore, the index signal generated in this way is 3 MHz away from the carrier of the luminance signal on the lower side, and the level of its sideband components has decreased, so the detection level when detecting the index signal may be incorrect. It becomes possible to set a margin with sufficient margin so that the detection is not detected. Furthermore, in this case, it is possible to set a plurality of frequencies as index signals by changing the frequency division ratio, etc., and search for a plurality of types or weight them.

Note that the index signal is not only recorded or erased when recording a video signal or an audio signal with a rotating magnetic head, but also the index signal is recorded or erased when a video signal or an audio signal is reproduced using a rotating magnetic head. You can also do that. In the latter case, the leakage of the index recording signal will affect the weak playback signal output, so when the index signal is supplied, the video signal and FM
It is better to send the audio signal to Mu1 appropriately.

In addition, in the above-1-1, the rotary magnetic head for recording and reproduction is used as the erasing head, but in a device equipped with a rotary magnetic head exclusively for erasing and its erasing signal, it is possible to use the rotating magnetic head for erasing the index signal. You can also do that.

〔effect〕

As described above, the present invention records or reproduces first information on a first portion of a track inclined with respect to the longitudinal direction of a magnetic tape using a rotating magnetic head, and records the first information or second information on a second portion of a track that is inclined with respect to the longitudinal direction of a magnetic tape. In a magnetic recording and reproducing device that records or reproduces information of the second information and records or erases an index signal of the first information or the second information at a predetermined position of the first portion,
The recording position of the first information is detected, and the time between the predetermined time after a certain period of time from the detected recording position and the time when the reference signal is generated corresponding to the rotational position of the rotating magnetic head = 20 - Opening the lid The index signal is recorded or erased at the timing corresponding to the detected time difference.
When recording or erasing the index signal on the first portion of the magnetic tape on which the first information has already been recorded, the recording or erasing position can always be set at a predetermined position;
No original index signal remains.

[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 timing chart thereof, and FIG. 3 is a timing chart of a conventional device. ]1-...Rotating drum 12...Motor 13...
・Frequency generator] 4... Pulse generator 15... Servo circuit 16
...Variable delay circuit]7...Pulse generation circuit 18.20.21...Switch 19...Control device 22...Recording amplifier 23...
- Index signal generation circuit 24... Index signal detection circuit 25... Preamplifier 26... Oscillation circuit 27...
・Position detection circuit 28... Processing circuit or higher

Claims (1)

[Claims] First information is recorded or reproduced in a first part of a track inclined with respect to the longitudinal direction of the magnetic tape by a rotating magnetic head, and the first information or second information is recorded in a second part of a track inclined with respect to the longitudinal direction of the magnetic tape. In a magnetic recording and reproducing device that records or reproduces information of the first information and records or erases an index signal of the first information or the second information at a predetermined position of the first portion, Detecting a recording position, detecting a time difference between a predetermined time after a certain period of time from the detected recording position and a time at which a reference signal is generated corresponding to the rotational position of the rotating magnetic head, and detecting the detected time difference. 1. A magnetic recording/reproducing device characterized in that the index signal is recorded or erased at a timing corresponding to the index signal.