JPH0224874A - Magnetic recorder - Google Patents

Abstract

PURPOSE:To prevent shifting of the starting and ending edges of a recording track due to the jitter of rotation by writing digital information by providing a buffer memory and supplying the digital information to a magnetic head by reading out the information based on the rotational phase information of the magnetic head. CONSTITUTION:A reference signal A is supplied to a phase servo circuit 21 and positive and negative pulses (PG signals) indicating the rotational phase of a drum are supplied to a waveform shaping circuit 23 from a detection head 5. Then the waveform-shaped PG signals C are returned to the servo circuit 21. Because of the signals C, a reset signal D readout enable signal E is supplied to a buffer FIFO memory 11 from a readout control circuit 16 with delay time T0. Then video information R is obtained from the memory 11 by reading out a reset signal D from the memory 11 by means of the signal E and the video information is recorded on a tape T by means of magnetic heads 1A and 1B after amplification. Since the timing for reading out the video information R from the memory 11 is changed at the same oscillating amplitude in the time base direction synchronously to a signal B when the rotation of the drum 2 is associated with jitter, the relative positions between the magnetic heads and tape do not change in respect of the scanning direction, and the starting and ending edges of a track are arranged at prescribed positions, resulting in stable data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording device suitable for recording digital signals.

[Summary of the invention]

The present invention provides a magnetic recording device equipped with a rotating magnetic head, in which a buffer memory is provided to write digital information to be recorded, which is then read out based on rotational phase information of the magnetic head and supplied to the magnetic head. This is to prevent the start and end ends of the recording track from shifting from predetermined positions due to jitter.

[Conventional technology]

In a conventional digital VTR, a rotating drum equipped with a magnetic head is controlled by phase servo, and a digital video signal is supplied to the magnetic head and recorded based on a reference signal for the phase servo.

[Problem to be solved by the invention]

The reference signal for the aforementioned phase servo is formed, for example, from the output of a crystal oscillator, and its period and phase are extremely stable.

However, since the rotation of the drum inevitably involves jitter, the time at which the magnetic head mounted on the drum passes a predetermined reference point varies. This fluctuation causes a problem in that the starting and ending ends of recording tracks formed on the magnetic tape are deviated from predetermined positions.

That is, if there is jitter in the rotation of the drum, the positive and negative pulses (so-called PC signals) indicating the rotational phase of the drum will differ from the phase servo reference signal shown in FIG.
As shown in , the angular distance α between the PG generating means and the magnetic head is
It fluctuates in the time axis direction with a fluctuation width Tj centered on the time point which has proceeded from the rise and fall of the reference signal by a time Tel corresponding to . This swing width Tj is, for example, 40μSp
p, and the jitter period is, for example, about several + fields.

On the other hand, the phase of the magnetic head mounted on the rotating drum is normally servo-controlled to match the phase of the reference signal, as shown in FIG. And, as shown in the same diagram,
After a predetermined 10-hour delay from the rise and fall of this reference signal, the digital video signal is supplied to the magnetic head and recorded on the tape.

In a digital VTR, it is necessary to record only valid video data that does not include a synchronizing signal portion, and the signal supply time Ts is set to be 2To shorter than the reference signal period Tref, so that Ts + 2 To = Tref.

This signal supply time Ts corresponds to the recording track length on the magnetic tape, and the time TO corresponds to the distance between the start of the recording track and the tape edge. These 10 hours are set to be larger than 172 of the jitter fluctuation width T'' described above.

When drum jitter occurs in the conventional digital VTR as described above, the rotational phase of the magnetic head changes as shown in Figure C, and the relative position between the head and the magnetic tape changes for each track in the scanning direction. . On the other hand, signals are supplied to the head at predetermined times based on the reference signal. As a result, if drum jitter occurs, the 51st
! As shown in FIG. 1, the starting and ending ends of the recording tracks on the magnetic tape are shifted from track to track in the scanning direction.

When the start or end of a track approaches the tape edge, the contact between the tape and the magnetic spatula L'' (so-called head contact) deteriorates, the data recording level decreases, and in severe cases, information may be lost at the track edge. arise.

In particular, since a preamble is recorded at the start of a track and a clock is reproduced from this preamble during playback, the loss of information at the start of a track becomes a serious problem.

To avoid such problems, if you set a large distance between the tape edge and the track end (recording margin),
The effective recording area of the tape decreases.

In the case of a multi-segment method in which one field is divided into a plurality of segments to record a large amount of data, the above-mentioned problems become even more pronounced.

In view of this, an object of the present invention is to provide a magnetic recording device that can form the start and end ends of a recording track on a magnetic tape at predetermined positions with high precision even when the rotation of a drum is accompanied by jitter. It's there.

[Means to solve the problem]

The present invention provides a magnetic head (
1 person), (1B) is connected to a magnetic recording device that records digital information on a magnetic tape T,
Buffer memo to write digital information! This is a magnetic recording device in which digital information is read out from this buffer memory based on phase information PG of a rotating drum and supplied to a magnetic head.

[Effect]

According to this configuration, due to jitter of the rotating drum,
Misalignment of the starting and ending ends of the recording track is prevented.

〔Example〕

Hereinafter, one embodiment of a magnetic recording device according to the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 shows the configuration of an embodiment of the present invention.

In FIG. 1, a pair of magnetic heads (IA) and (IB) are shown.
) are mounted on the rotating drum (2) at angular intervals of 180°,
This drum (2) is driven by a motor (3). (
4^) and (4B) are magnets, which are attached to the drum (2) in advance of the magnetic heads (1^) and (IB) by an angle α, respectively. A magnetic head (5) for detecting the magnet (4^) and (4th) is appropriately provided close to the drum (2).

(lO) is a signal system, (11) is a first-in/first-array (FIFO) memory, and an input terminal (
12), for example, an 8-bit parallel digital video signal is written into the FIFO memo! Parallel video data read from I (11) is converted into serial data in a parallel-serial converter (13), and is sent alternately to the magnetic head (1 person) and (1B) via the recording amplifier (14). supplied to

Writing data to Memo 'J (11) and Memo IJ (1)
1), each write control circuit (
15) and a continuous control circuit (16).

The phase servo circuit (21) of the drum servo system (20) is supplied with the output of the reference signal generator (22), and
The output of the detection head (5) is supplied via a shaping circuit (23). The output of this shaping circuit (23) is the signal system (10
) is also supplied to the continuation control circuit (16).

The output of the phase servo circuit (21), that is, the phase error signal, is added to the speed error signal from the speed servo circuit (not shown) in the adder (24), and the output is added to the speed error signal from the speed servo circuit (not shown).
5) to the motor (3).

Next, the operation of the embodiment shown in FIG. 1 will be explained with reference to FIGS. 2 and 3.

Similarly to the above, the reference signal (2) as shown in FIG. 2 is supplied from the generator (22) to the phase servo circuit (21).

The PG signal as shown in the same figure is supplied from the detection head (5) to the shaping circuit (23), and the shaped PG multiplied signal as shown in figure C is supplied to the phase servo circuit (21) to control the phase servo. A loop is formed.

In addition, the shaped PG multiplied signal is supplied to the readout control circuit (16), from which the continuous reset signals ■ and Read enable signal [F] is F
IFO memo! j (11).

In the FIFO memo 'J (11), video data ■ as shown in W in the figure is written by a write reset signal [F] and a write enable signal ⊚ as shown in F and G in the figure. This video data [stock] is read out at the timing of the reset signal (2) and the duration of the enable signal (2) to obtain video data (2) as shown in FIG. The read video data■ is sent to the recording amplifier (
14), through the magnetic field 1^), (IB)
is supplied to the magnetic tape T and recorded on the magnetic tape T.

When the rotation of the drum (2) is accompanied by jitter, the PG signal signal and the shaped PG multiplication signal fluctuate in the time axis direction with a fluctuation width Tj, as shown by the one-dot chain line and the two-dot chain line in Fig. 2B and C. do.

Correspondingly, the reset signal ■ and the enable signal ■ from the successive control circuit (16) are also synchronized with the PG signal, as shown by the dashed line and the dashed double dotted line in the same diagram.
It fluctuates in the time axis direction with the oscillation width TJ.

This allows FIFO memo! The timing for reading video data ■ from J (11) is indicated by the dashed line and 2
As shown by the dotted chain line, the swing width T is synchronized with the PG signal.
” and fluctuates along the time axis.

As described above, in this embodiment, even if the rotation of the drum (2) is accompanied by jitter, the video data is read out from the FIFO memo IJ (11) in synchronization with the rotational phase of the drum (2), and the magnetic Since the magnetic heads (IA) and (1B) are supplied, the relative positions of the magnetic heads (IA) and (1B) and the tape T do not change in the scanning direction during each signal recording period.

Therefore, as shown in FIG. 3, the recording tracks formed on the magnetic tape T according to this embodiment have their starting and ending ends aligned at predetermined positions, ensuring good head contact and ensuring data stability. will improve.

〔Effect of the invention〕

As described in detail above, according to the present invention, a buffer memory is provided to write digital information to be recorded, and this is read out based on the rotational phase information of the magnetic head and supplied to the magnetic head. Due to the jitter of
A magnetic recording device can be obtained in which displacement of the start end and # end of a recording track is prevented, and the stability of data at both ends of the track can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the magnetic recording device according to the present invention, FIGS. 2 and 3 are time charts and track patterns for explaining the operation of the embodiment of the present invention, and FIG. FIG. 5 shows a time chart and a track pattern for explaining the operation of a conventional magnetic recording device. (IA), (1B) are magnetic heads, (2) are rotating drums, (4A), (4B) are magnets, (5) are detection heads, (11) are FIFO memory, (16) are continuous control circuits, (21) is a phase servo circuit, and (22) is a reference signal generator.

Claims (1)

[Claims] In a magnetic recording device that records digital information on a magnetic tape via a magnetic head mounted on a rotating drum, a buffer memory for writing the digital information is provided, and the buffer memory records the digital information from the rotating drum. A magnetic recording device characterized in that the digital information is read out based on drum phase information and supplied to the magnetic head.