JPH0770112B2 - Digital magnetic recording device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a digital magnetic recording apparatus suitable for overwriting recording using a rotary head in a rotary head type digital audio tape recorder, for example. Is.

[Conventional technology]

FIG. 6 shows a signal pattern recorded on the medium of a PCM recorder using a VTR disk as a conventional digital audio tape recorder. In the figure, (1) is a medium for recording a signal, (2) is a video signal track pattern recorded by a rotating head, and (3) is a control recorded by a rotating head for controlling tape running. A signal (CTL) track pattern, (4) is a fixed head for completely erasing the signal recorded on the medium.

Next, the operation will be described. In a conventional PCM recorder, an audio signal converted into PCM is FM-modulated with respect to a medium (1) and recorded on a video track (2) of a VTR by a rotating head.

Also, to play the recorded signal, the video track (2)
The rotating head needs to be accurately scanned over it. For that purpose, the tracking information at the time of recording is CTL by using a fixed head.
Record the signal of several 10Hz in the signal track (3),
At the time of reproduction, reproduce the signal of the CTL signal track (3),
It was used as a control signal for the capstan motor that controls tape running.

[Problems to be solved by the invention]

The conventional PCM recorder has become the recording format as described above, and in addition to the rotating head that records the PCM audio signal, the CT that controls tape running during playback.
A fixed head was needed to record the L signal. Also, in the conventional PCM recorder, when trying to overwrite the already recorded medium, the CTL signal is several tens of Hz.
Since it is a low frequency, it is recorded up to the deep layer, and it was necessary to write a new signal after erasing the entire surface of the medium using a dedicated erasing head. Further, due to the erasing method using the fixed head (4), there is a problem that the shaded portion is left unerased in principle.

The present invention has been made to solve the above problems, and it is possible to record a PCM audio signal and a tape running control signal only by a rotating head without using a dedicated fixed head. It is an object of the present invention to provide a digital magnetic recording device capable of obtaining good overwrite performance in overwriting of an information signal by a rotating head without using an erasing dedicated head.

[Means for solving problems]

The digital magnetic recording apparatus according to the present invention selects from among the digital signal and the plurality of types of tracking control signals based on the timing signal indicating the timing at which the digital signal and the plurality of types of tracking control signals are respectively recorded on the recording medium. Recording signal selection means for selecting a signal to be recorded on a recording medium, a recording amplifier for outputting a recording current of the signal to be recorded to the plurality of rotary magnetic heads, and tracking having the lowest frequency among the plurality of types of tracking control signals. And a recording current control unit for controlling the recording current so that the recording current of the control signal becomes smaller than the recording currents of the other tracking control signals.

[Action]

In the present invention, the recording current control means controls the recording current of the tracking control signal having the lowest frequency among the plurality of types of tracking control signals so as to be smaller than the recording currents of the other tracking control signals. The recording depth of the tracking control signal having the lowest frequency on the recording medium can be made closer to the recording depths of other tracking control signals.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, (1) is a medium for recording information, (5) is a rotary head for recording a signal on the medium (1), and has heads H _A and H _B with different azimuth angles. (6) is a selector for converting signals input in parallel into serial signals divided into areas, (7) is a recording current adjusting circuit for controlling the signal level input from the selector (6),
(8) is a volume for controlling the level output from the recording current adjusting circuit (7), (9) is an resistor for attenuation, and the output of the recording current adjusting circuit (7) is divided into areas by the switch of (10). It is provided to control the current. (11) is a gate for operating the switch (10) only in a specific area, and (12) is a recording amplifier provided for recording the signal input from the recording current adjusting circuit by the rotary head (5). Is.

FIG. 2 is a track format applied to the apparatus of the present invention, and FIG. 3 is an ATF (Aoutomatic-Track-Findind) for controlling tape running in the apparatus of the present invention.
FIG. 4 is a signal level diagram of the area, and FIG. 4 is a timing diagram for explaining the operation of the device of the present invention.

An embodiment of the present invention will be described below in detail with reference to FIGS.

In FIG. 1, by sequentially scanning the medium (1) with a plurality of rotating heads (5) H _A and H _B having different azimuth angles,
As shown in FIG. 2, H _A and H _B of the rotary head (5) record signals at a predetermined azimuth angle every 1 field (track). It should be noted that various information is recorded in each track at a predetermined position by area division.
FIG. 2 is a track format applied to the apparatus of the present invention.

As described above, the device of the present invention uses the audio signal converted into the PCM and the tape running control signal (hereinafter ATF (Automatic-Track-Fin for the device of the present invention.
Ding)) can be recorded on the same track by the rotating head (5).

In FIG. 2, an audio signal is digitally modulated and recorded at a carrier frequency of 9.408 MHz in the PCM area.

Also, the ATF signal has a duty cycle of 50%.
KHZ (f ₁ ), 522KHZ (f ₂ ), 784KHZ (F ₃ ), 1.568MHZ (f ₄ )
The ATF area is further divided into areas and recorded in a 4-track cycle format.

In order to understand the purpose of the present invention, the AT
It is necessary to be aware of the method of processing the F signal, and the operating principle will be briefly explained.

In Fig. 2, during playback, the head of H _A with an azimuth angle of + 20 ° of the rotating head (5) was recorded with the head of H _B with an azimuth angle of -20 ° together with the track recorded with the self-head. Scans across both adjacent tracks.

When H _A of the rotating head (5) scans the ATF area in such a state, the f ₁ signal with a recording frequency of 130 KHZ recorded on both adjacent tracks does not suffer azimuth loss and the head H _A It is reproduced as a signal level that is almost proportional to the width of the crossing track. Figure 3 shows the head H _A
It shows a signal to be reproduced when the ATF area is scanned. When head H _A is at scan point X ₁ , f _{1 of} HB1 track
Signal and f ₂ signal of its own track (HA1) (f ₂ H of Fig. 3 (C))
A1) is frequency-multiplexed and reproduced. It is determined that the f ₂ signal is the one of the odd track recorded by the head H _B, and the f ₁ signal currently being frequency-multiplexed and reproduced is
It becomes the timing signal (SYNC signal) that samples and holds the f ₁ signal level. On the other hand, it is previously determined by area division that the f ₁ signal of the even track recorded by the head H _B exists at the point X ′ ₁ after detecting the f ₂ signal. As a result, the f ₁ level sampled and held at the point X ₁ in advance (f ₁ H _B 1 in FIG. 8B) and the f ₁ level reproduced at X ′ ₁ (FIG. 3B). F ₁ H
_B 0) can be compared, and if the tape running is controlled so that the value of the comparison level is constant, H _A and H _B of the rotating head (5) are recorded by the self-head. It is possible to on-track on the track,
Good tracking performance is obtained. The track SYNC signal recorded at head H _B is f ₃ . The f ₄ signal Figure 3 (a), it is necessary to increase the frequency to the extent that no influence of the disturbance on the signal f ₁ ~f _3. As a result, f ₄ = 1.568MHZ is used.

I think that I could understand the principle of tape running control using the ATF signal in the above explanation.

In a device to which the ATF signal format is applied, when overwriting is performed on a recorded medium, it is possible to reduce the size of the device and increase the size of the device by overwriting the signal by the rotating head. It is essential for functionalization.

In this case, it should be noted that the recording phase of the original recording pattern and the pattern to be recorded later do not always match when overwriting is performed on the recorded medium. F ₁ at f ₄ and f ₂ at f ₁
Alternatively, good overwrite characteristics must be obtained when overwriting f ₃ or vice versa. Therefore, it is desirable that the recording depth of each frequency on the medium is the same in f _{1 to} f ₄ .

The recording depth becomes shallower at higher frequencies due to another cause called recording demagnetization. That is, when the recording frequency is low due to the spread of the head magnetic field, the magnetization is determined by the magnetic field at the center of the gap, but when the frequency becomes high, the polarity is reversed while the recording point passes through the head magnetized region. This is called recording demagnetization.

Therefore, in the present invention, the recording depth to the medium is aligned as much as possible with respect to the ATF-related signals of different frequencies f _{1 to} f ₄ by the following specific means, and good signal overwriting is realized. ing.

When recording a signal from a head to a medium in magnetic recording,
The output magnetic flux Hg from the headgear that determines the writing strength is given by equation (1).

Where N: number of turns of coil i: recording current μ: magnetic permeability of core μ ₀ : vacuum permeability Sg: cross section of gear sc Sc: cross section of core g:
Gap length When the recording current in Eq. (1) is constant for each frequency f _{1 to} f ₄ , the strength of Hg is determined by the frequency characteristics of the core transmittance. The transmittance of the core is higher at lower frequencies and lower at higher frequencies. The slope is
Depends on core material.

Therefore, the magnetic flux output from the headgear is stronger at lower frequencies and weaker at higher frequencies. As a result, the recording depth becomes deeper at lower frequencies and shallower at higher frequencies.

Therefore, in the apparatus of the present invention, in one embodiment shown below, the recording current of f ₁ is lowered to make the recording depth shallow for low frequencies, and the recording depth of f ₁ is recorded at f _{2 to} f ₄ . It is closer to the depth to improve the overwrite characteristics.

That is, in FIG. 1, the frequencies (f _{1 to} f ₄₎ which are ATF-related signals and the PCM data are shown in FIGS. It has been entered. These signals are selected by control signals f, g, and h (FIGS. 4 (f), (g), and (h)), and are serially output by area division. Is input to the recording current adjusting circuit (7). The recording current adjusting circuit includes a volume (8), an attenuation resistor (9), and a switch (SW).
The gate (11) is set to Low and the SW (10) is set to the side only in the area where f ₁ is selected in the selector (6) so as to reduce the recording current to the recording amplifier (12). As a result, the output current of the recording amplifier (12) shown in FIG. 4 (j) is obtained.

According to the above-described embodiment, the recording depth of the medium of f ₁ frequency recorded on the medium (1) from H _A and H _B of the head (5) is controlled to be shallow.

Although the means for controlling the recording current by attenuating the input level to the recording amplifier (12) has been described in the above embodiment, the same effect can be obtained by controlling the gain of the recording amplifier (12).

Further, in the above embodiment it has been configured so as to lower the recording current for only f ₁ signal, f ₁ by the circuit configuration shown in FIG. 5
Each recording current for each frequency of up to f ₄ is provided in the current adjusting circuit (14) by the output of the switch switching circuit (13). Switch switching f ₁ current <f ₂ current <f ₃ current <f It is clear from the matters described in the above embodiment that the overwrite characteristic is further improved by setting the current to _four .

〔The invention's effect〕

As described above, according to the present invention, the recording current of the tracking control signal having the lowest frequency among the plurality of types of tracking control signals is controlled so as to be smaller than the recording currents of the other tracking control signals. By doing so, the recording depth of the tracking control signal with the lowest frequency to the recording medium can be made close to the recording depth of the other tracking control signals, and therefore the recording control signal with the lowest frequency is recorded. When the area is overwritten with another tracking control signal to be rewritten, the unerased portion can be suppressed to ensure a good overwrite characteristic, and a device having stable tracking performance can be obtained.

Furthermore, by controlling the recording current so that the recording currents of other tracking control signals become smaller as the frequency becomes lower, each recording depth can be made closer to the recording depth of the tracking control signal of a higher frequency. Therefore, when the areas in which the respective tracking control signals are recorded are overwritten with the tracking control signals having a frequency higher than that, rewriting is suppressed, and good overwrite characteristics can be secured.

[Brief description of drawings]

1 is a circuit block diagram showing an embodiment of the present invention, FIG. 2 is a track format applied to the apparatus of the present invention, FIG. 3 is a signal level diagram of an ATF area in the apparatus of the present invention, and FIG. FIG. 5 is a timing diagram for explaining the operation of FIG. 1, FIG. 5 is a block diagram of another embodiment circuit of the present invention,
FIG. 6 is a track pattern diagram of the conventional device. In the figure, (1) is a medium, (5) is a rotary head, (6) is a selector, (7) is a recording current adjusting circuit, (8) is a volume, (9) is an attenuator resistor, and (10) is a switch.
(11) is a gate, and (12) is a recording amplifier. The same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yutaka Kaneba No. 1 Baba Institute, Nagaokakyo City, Kyoto Prefecture Mitsubishi Electric Corporation Electronic Product Development Laboratory (56) References JP 61-73223 (JP, A)

Claims (2)

[Claims] 1. An apparatus for recording a digitally modulated digital signal on a track having a plurality of rotary magnetic heads, the track being formed at a predetermined angle with respect to the longitudinal direction of a recording medium, wherein the digital signal and the respective frequencies are recorded. Differently, in a digital magnetic recording apparatus for recording a plurality of types of tracking control signals for controlling tracking on the track at the time of reproduction by dividing them into predetermined areas of the track, the digital signal and the plurality of types of tracking control are recorded. Recording signal selection means for selecting a signal to be recorded on the recording medium from the digital signal and the plurality of types of tracking control signals based on a timing signal indicating the timing at which each signal is recorded on the recording medium; Signal to be recorded on the rotating magnetic head A recording amplifier that outputs a recording current, and the recording current of the tracking control signal having the lowest frequency of the plurality of types of tracking control signals is controlled to be smaller than the recording currents of the other tracking control signals. A digital magnetic recording device comprising a recording current control means. 2. The recording current control means controls the recording current of the other tracking control signal so that the recording current becomes smaller as the frequency thereof becomes lower. Digital magnetic recording device.