JPH0460943A - Digital magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate an effect of adjacent cross talk and to expand a tracking margin by reproducing a digital signal of one track with N pieces of magnetic heads being smaller in width than a track pitch, selecting a reproducing output in the best on-track condition out of the reproducing outputs and reproducing it accordingly. CONSTITUTION:The reproducing is performed by using the magnetic heads 1-3 being smaller in head width Tw than the track pitch Tp, disposed to be capable of reproducing the digital signal recorded in one track provided with an overlap part in the track widthwise direction. Then, three outputs outputted from the magnetic heads 1-3 are processed to be reproduced in parallel, and one of outputs of three reproducing processing circuits 5-7 is selected according to a reproducing state. By this method, an effect of the adjacent cross talk is eliminated, and the apparent head width is expanded, thus expanding the tracking margin.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a digital magnetic recording and reproducing device for recording and reproducing digital signals, and is capable of widening the apparent width of a magnetic head without being affected by crosstalk from adjacent tracks. The present invention relates to a digital magnetic recording and reproducing apparatus that reproduces digital signals by expanding the tracking margin.

Conventional technology Conventionally, recording and reproducing devices used in home VTRs are as follows:
Video signals are azimuthally recorded on a video track using two magnetic heads with different azimuths, and on the playback side, azimuth loss is used to eliminate adjacent crosstalk from adjacent tracks, achieving guard panless recording. .

Also, the head width Tw is larger than the track pitch Tp (
T w > Tp) Tracking errors such as linearity errors are guaranteed using a magnetic head.

In addition to the video track, the tracking error detection circuit records a control track in the longitudinal direction of the magnetic tape using a pulse indicating the rotational phase of the head drum as a control signal. The tracking error is detected by comparing the phase of the head drum and the rotational pulse of the head drum (for example, supervised by Ryo Takahashi, VTR technology (Japan Broadcasting Corporation)).

On the other hand, the tracking error detection circuit used for 8mm video sets four low-frequency high lots with different frequencies, and frequency-multiplexes the low-frequency pilot video signal into the video signal, one for each rack. . During playback, two low frequency pilots recorded on both adjacent video tracks are detected as crosstalk from adjacent video tracks, and a tracking error is detected by comparing the power difference between the two low frequency pilots.

Problems to be Solved by the Invention However, when the above-mentioned conventional guard panless recording is applied to a digital magnetic recording/reproducing device, the recorded digital signal has signal components up to the low frequency region, so that no significant azimuth loss can be obtained on the reproduction side. , leading to an increase in adjacent crosstalk.

In addition, in order to improve recording density, conventional home VTR
If the track is made narrower, the effect of azimuth loss becomes smaller, leading to an increase in adjacent crosstalk. Therefore, it becomes impossible to make the head width Tw of the magnetic head larger than the track pitch Tp, and tracking errors cannot be guaranteed.

Furthermore, in the method of using a control track in a tracking error detection circuit, it is not possible to detect the video track linearity, and it is very difficult to improve the tracking error detection accuracy.

Furthermore, although the tracking error detection device used for 8mm video can detect video track linearity, frequency multiplexing of low frequency pilots is difficult for digital signals that contain signal components up to the low frequency region. There were problems such as interference waves.

The present invention has been made in view of this point, and aims to widen the apparent track width by using N magnetic heads, thereby increasing the tracking margin without being affected by adjacent crosstalk.

In addition, the tracking error is detected by comparing the power of the reproduction signal reproduced from two of the N magnetic heads, so there is no need to use a pilot signal. It is an object of the present invention to provide a tracking error detection circuit that can detect video track linearity, improve tracking error detection accuracy, and do not interfere with digital signals.

Means for Solving the Problems In order to achieve the above object, the digital magnetic recording and reproducing apparatus of the present invention (claim 1) adds a synchronization signal and an ID signal (a signal indicating the address of data) to input digital information. A digital magnetic recording and reproducing device that records and reproduces a digital signal with an error correction code added to a magnetic recording medium.
N magnetic heads whose head width Tw is smaller than the track pitch Tp and which are arranged so that they can be reproduced by providing an overlap part in the track width direction, and N outputs output from the N magnetic heads are reproduced in parallel. and a selection circuit that selects one of the outputs of the N reproduction processing circuits according to the reproduction state.

Further, in order to achieve the above object, the digital magnetic recording and reproducing apparatus of the present invention (claim 4) records a digital signal obtained by adding a synchronization signal, an ID signal, and an error correction code to input digital information on a magnetic recording medium. A digital magnetic recording and reproducing apparatus for recording and reproducing data with different azimuths for each adjacent track, the track being arranged so that a digital signal recorded on the one track can be reproduced by providing an overlap part in the track width direction.・The head width Tw is smaller than Sokpi and Sochi Tp, and the N outputs from the N magnetic heads are reproduced in parallel. N reproduction processing circuits, a selection circuit that selects one of the outputs of the N reproduction processing circuits according to the reproduction state, and reproduction at a distance 1/2Tp position from the center of the N magnetic rads. death,
and a tracking error detection circuit that detects a dragging error from a power difference between reproduction outputs output from two of the N magnetic heads that reproduce symmetrical positions in the track width direction. There is.

Operation The present invention has the above-described configuration, and is arranged so that during reproduction, a digital signal recorded on one track can be reproduced by providing an overlap part in the track width direction, and the width N is smaller than the track pitch Tp. Since reproduction is performed using two magnetic heads, the influence of adjacent crosstalk is eliminated, the apparent head width is widened, and the tracking margin can be increased.

In addition, tracking errors are detected by comparing the playback output using two of the N magnetic heads, so tracking including bidet first and rack linearity is detected. Errors can be detected and tracking error detection accuracy can be improved.

Furthermore, since pilots and the like are not frequency multiplexed on low frequencies, there is no interference with digital signals.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a main part of a digital magnetic recording/reproducing apparatus according to a first embodiment of the present invention (provided that the number N of magnetic heads is three).

The magnetic recording medium 4 records a digital signal, as shown in FIG. 3, in which a synchronization signal, an ID signal, and an error correction code are added to input digital information.

Each track of the digital signal recorded on the magnetic recording medium 4 has the same azimuth as the recording and has a track pitch T.
Three magnetic heads 1 having a head width Tw smaller than p
．． 2. 3.

As shown in FIG. 2, even if the linearity of track and track of the three magnetic heads changes and the on-track conditions change from magnetic head 1 to magnetic head 2, the magnetic heads 1 and 2
T in the track width direction to prevent the playback output from deteriorating between
The head arrangement is such that an overlapping portion is provided for each p-Tw for reproduction.

Next, referring to FIG. 1, a magnetic head L, 2. The reproduced digital signal outputted from 5.3 is processed by a reproduction processing circuit 5.3 having the same configuration. 6. 7 to be processed in parallel. Reproduction processing circuit 5. 8. 7 is a head amplifier 10 and an integral detection section 11;
, a synchronization/ID detection section 12 , and the head amplifier 10 amplifies the digital signal reproduced from the magnetic head and outputs it to the integral detection section 11 . The integral detection section 11 performs integral detection and generates a clock and a binary digital signal synchronized with the clock. Next, the synchronization ΦfD detection unit 1
2, the synchronization pattern and the I
D signal is detected and a regular byte-based digital signal is generated.

Next, the reproduction processing circuit 5. 6. The output from 7 is input to a selection circuit 8. The selection circuit 8 includes an error detection section 13 and a selection section 14. The error detection unit 13 detects the number of errors in one synchronization block shown in FIG. 3 by the reproduction processing circuit 5.
6. 7, and the output of the reproduction processing circuit with the least number of errors in the synchronization block of the same ID signal is detected and outputted to the selection section 14. The selection section 14 selects the output of the reproduction processing circuit 5.6.7 for each synchronous block according to the output of the error detection section 13, and selects the reproduced digital signal with the least number of errors.

Therefore, if the configuration is as described in item 1, the reproduction output of the magnetic head with the least error will be selected.
In other words, the magnetic head with the best on-track condition is selected. Therefore, as shown in FIG. 2, if a magnetic head with a head width Tw smaller than the track pitch Tp is arranged, the output of the magnetic head without adjacent crosstalk will always be selected even if the linear I arity changes. , it is possible to eliminate adjacent crosstalk, increase the apparent head width TW, and increase tracking margin.

Next, returning to FIG. 1, the tracking error detection circuit 9 will be explained. The tracking error detection circuit 9 compares the powers of reproduction signals reproduced from the head amplifiers 10 forming the reproduction processing circuits 5 and 7. Here, the output of the head amplifier 10 is the reproduction output of the magnetic heads 1 and 3 shown in FIG. 2, and the magnetic heads 1 and 3 mainly reproduce the position 1/2Tp from the center of the three magnetic heads. It is located at a symmetrical position from the center of the three magnetic heads. Therefore, when the center of the track coincides with the center of three magnetic heads, magnetic head 1
The power values of the reproduction outputs of and 3 match. However, in the above case, it is necessary to change the azimuth for each adjacent track in order to alleviate the influence of adjacent crosstalk.

Therefore, referring to FIG. 1, the tracking error detection circuit 9 is extremely useful because it can detect tracking errors including linearity by comparing the reproduction outputs of the magnetic heads 1 and 3.

Further, in the above embodiment, the case where the number of magnetic heads is three is described, but the number N of magnetic heads is 2 or more.
Even two will work. Furthermore, if the number N increases, the apparent head width Tw can be further widened (Tw
= (N-1)*Tp-(N-2)*Tw).

Furthermore, if the track pitch Tp and the head width Tw are made equal, it is impossible to adopt the overlapping arrangement shown in Fig. 2 without deteriorating the playback output, but if some degree of playback output deterioration is allowed, the arrangement shown in Fig. It is possible to obtain the same effect as in the above embodiment.

In addition, when the running system changes, such as during variable speed playback, the playback angle of the track changes, making it difficult to on-track.However, if the embodiment 1 is used, the apparent head width can be widened. This is extremely useful for variable speed playback, etc.

Furthermore, even if the magnetic head arrangement shown in Fig. 2 is used in a non-tracking mode without tracking, the above-mentioned principle also allows
A reproduced digital signal without adjacent crosstalk can be obtained.

Effects of the Invention As described above, according to the first embodiment of the present invention, one track of digital signals can be reproduced by providing an overlap portion in the track width direction using N magnetic heads with Tp>Tw. Since the configuration is such that the playback output with the best on-track conditions is selected and played back, the influence of adjacent crosstalk can be eliminated and the apparent head width can be widened. Therefore, it is possible to cope with tracking deviations such as changes in linearity.
Tracking margin can be expanded.

Further, according to the present invention, 1 from the center of the N magnetic heads.
Since the tracking error is detected by comparing the reproducing power of two magnetic heads out of N magnetic heads symmetrical in the track width direction that reproduce the /2Tp position, the linearity of the video track is included. Tracking errors can be detected, and since pilots and the like are not frequency multiplexed on low frequencies, tracking errors can be detected without interfering with the reproduced digital signal, making it extremely easy to detect tracking errors.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of a digital magnetic recording and reproducing apparatus showing an embodiment of the present invention, FIG. 2 is a layout diagram showing the reproducing position of the magnetic head of the present invention, and FIG. FIG. 1, 2. 3...Magnetic head, 4...Magnetic recording medium, 5, 6. 7... Regeneration processing circuit, 8.
...Selection circuit, 9...Tracking error detection circuit,
10... Head amplifier, 11... Integral detection circuit, 12... Synchronization/ID detection section, 13...
Error detection section, 14... selection section. Name of agent: Patent attorney Shigetaka Awano 1 person = 15-

Claims (4)

[Claims] (1) A digital magnetic recording and reproducing device that records and reproduces a digital signal in which a synchronization signal, an ID signal, and an error correction code are added to input digital information on a magnetic recording medium, and the digital information is recorded on one track. N magnetic heads having a head width Tw smaller than the track pitch Tp, which are arranged so that digital signals can be reproduced with an overlapping portion in the track width direction, and N outputs outputted from the N magnetic heads. A digital magnetic recording and reproducing device comprising: N reproducing processing circuits that perform reproducing processing in parallel; and a selection circuit that selects one of the outputs of the N reproducing processing circuits according to a reproducing state. (2) N magnetic heads are arranged 2Tw- in the track width direction.
2. The digital magnetic recording and reproducing apparatus according to claim 1, wherein the digital magnetic recording and reproducing apparatus is arranged so that reproduction can be performed in an overlapping manner every Tp. (3) The digital magnetic recording/reproducing apparatus according to claim 1 or 2, wherein the selection circuit selects the output of the reproduction processing circuit with the least number of errors in the error correction code and uses the output as the reproduced digital signal. (4) A digital magnetic recording and reproducing device that records and reproduces a digital signal in which a synchronization signal, an ID signal, and an error correction code are added to input digital information on a magnetic recording medium with different azimuths for each adjacent track. N magnetic heads having a head width Tw smaller than the track pitch Tp and having the same azimuth as the recording track are arranged so that a digital signal recorded on one track can be reproduced with an overlap part provided in the track width direction. and a selection circuit that selects one of the outputs of the N reproduction processing circuits depending on the reproduction state. and reproduction signals reproduced from two magnetic heads of the N magnetic heads that reproduce a position 1/2Tp distance from the center of the N magnetic heads and reproduce symmetrical positions in the track width direction. A digital magnetic recording/reproducing device comprising a tracking error detection circuit that detects a tracking error from a power difference between the two.