JPH046601A - Magnetic recording device - Google Patents

Abstract

PURPOSE:To attain the reproduction at a high azimuth angle and to prevent crosstalk from an adjacent track by providing a mechanism forming a 2nd recording track without overlap on a 1st recording track with a 2nd rotary magnetic head after erasing part of the 1st recording track to the recording device. CONSTITUTION:A magnetic tape 1 is driven in the direction of the arrow and wound on a rotary cylinder by a guide post 6. A track 9 is recorded when a video recording head 2 scans obliquely with respect to the tape running direction, then an erasure head 4 scans while being overlapped onto part of the track 9 and the overlapped part (DELTAW) is completely erased and the width of the track 9 is TP. Then a head 3 is scanned so that the end of the track 9 is arranged with the end of the track by the video recording head 3 and a new track 10 is recorded without a gap to the track 9. Thus, a high quality signal is subject to guard band less recording at a large azimuth angle and crosstalk from an adjacent track due to head tracking deviation at the reproduction is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a helical scanning magnetic recording device in which a rotating magnetic head scans obliquely to the running direction of a magnetic tape.

Conventional technology Among the magnetic recording devices currently in practical use, the home VTR achieves the highest recording density.This home VTR has the ability to reduce tape consumption and achieve long recording times. Because of this, he holds a guard pan dress record. That is, this is a method in which no unrecorded portions (guard bands) are provided between tracks recorded on the tape. In this method, there is crosstalk from adjacent tracks during reproduction, and in order to reduce crosstalk, azimuth recording and reproduction using reproduction azimuth loss is performed.

Problems to be Solved by the Invention However, as is well known from the image quality problems in long-time modes such as VH3, the anomalous angle is currently small and its crosstalk reduction effect is not sufficient. FIG. 3 schematically shows a magnetization pattern on a magnetic tape recorded in a guard panless state by azimuth recording in a home VTR.

θ in the figure is hereinafter referred to as the azimuth angle. Crosstalk Lc (unit: dB) from adjacent tracks during reproduction in the tracking state shown in FIG. 3 is expressed by the following equation. However, the reproduction output from the recording track width W0 is set to 0 dB.

By the way, the first term in the right-hand side 11 of the above equation (1) is the ratio of the on-track width (Wl) to the playback track width (Wo) in the adjacent track, and the second term in the right-hand side 1] is: This shows the playback azimuth loss in adjacent trunks. Since crosstalk is a product of the second terms, it is ideal to make one of the terms zero.

In order to make the first term zero, it is necessary to reproduce with a head that has a track width equal to the recording track width, and this is
As shown in the figure. As can be seen from FIG. 4, in this case, tracking deviation immediately causes an increase in cross-storage, and there is no margin for tracking and king during re-travel.

On the other hand, the second term will be discussed below. Current VH3,5
In the -VH3 system, considering the trunking accuracy, W+ is 2.7 to 8.7 μm, and the wavelength is approximately λ−0.7 to 5.3 μm from the luminance band of the video signal. Therefore, W+/λ-0.5 to 13.3, and the second term on the right side of the above equation in this range is L(θ) (unit: dB), and the calculation results are shown in Figures 5(a) to (d). Shown below. From the figure, it can be seen that the larger the azimuth angle θ, the smaller the crosstalk. Also, in VHS and 5-VH3 systems, θ-12
1, crosstalk is hardly reduced when W+/λ≦1.0, ideally the azimuth angle is 90″
However, in the range of 80@≦θ≦100°, the crosstalk is so small that it does not pose a practical problem.When the azimuth angle θ is in the above range, the crosstalk will occur regardless of the value of the first term WI. Since this is sufficiently small, a head with a wider track width than the recording track width can be used, and there is sufficient tracking margin. However, since the azimuth angle is large when recording the next track 2 (hereinafter referred to as override) while partially overlapping the edge of the previously recorded track l, the recording signal of track 1 (especially track edges) may not be erased sufficiently. In such a case, even if accurate tracking is performed during playback, the unerased signal component of track 1 in track 2 will be reproduced as crosstalk, and if the recording track becomes narrower, the aforementioned unerased portion will be increased,
Image quality deterioration due to crosstalk becomes even more obvious.

The present invention has been made to solve the above-mentioned problems, and aims to provide a magnetic recording device that eliminates the problems caused by high azimuth angle recording, has sufficient tracking margin, and is free from crosstalk.

Means for Solving the Problems In order to achieve the above object, the present invention has a method in which a magnetic tape is wound around the outer periphery of a tape guide drum having at least two erasing heads among a plurality of rotating magnetic heads and is run. After the rotating magnetic head is scanned in a direction diagonal to the tape running direction, and the erasing head erases a part of the first recording track on the magnetic tape recorded by the first rotating magnetic head. has a mechanism for forming a second recording track with a second rotating magnetic head without overlapping the first recording track, and the track width of the rotating magnetic head is made wider than the recording track width on the magnetic tape. This is what I did.

According to the present invention, since the area that has conventionally been overridden is completely erased by the erasing head in advance, there is no crosstalk due to unerased areas, and the width of the track is wider than the track width recorded on the magnetic tape. Since it is possible to reproduce at a high azimuth angle using a head with a wide track width, it is possible to prevent crosstalk from adjacent tracks, and there is sufficient tracking margin.

Embodiment No. 111ffi (a) is a conceptual diagram of a mechanism section for recording video signals on a magnetic tape of a helical scanning video tape recorder according to the present invention, and FIG. 1 (b) shows a recording process on a magnetic tape. It is something that The recording mechanism section is composed of a magnetic tape 1, a magnetic head 2°3 for video recording, a magnetic head 4.5 for erasing, a guide post 6°7, and a rotating cylinder 8. The relationship between the track width (T,) of the erasing head and the track width (T,) of the erasing head is set to satisfy the following equation.

Tw < 2 X Tp, Tt > T+m T
Furthermore, the gaps of the video recording heads 2 and 3 are tilted in opposite directions, and in this embodiment, the tilt angle is θ/
2-±45°. The magnetic tape 1 runs in the direction of the arrow in the figure and is wound around a rotating cylinder by the guide post 6. (a) When the video recording head 2 scans diagonally with respect to the tape running direction, tracks 9 are recorded; ) Next, the erasing head 4 scans while overlapping a part of the track 9, and the overlapping part (ΔW) is completely erased, and the track 9 is completely erased.
The width of is T, (=T.

ΔW).

(C) Then, the head 3 scans so that the track end of the video recording head 3 is aligned with the end of the track 9, and a new track 10 is recorded without any gap between the track 9 and the track 9.

(d) Next, the erasing head 5 completely erases a part (ΔW) of the track 10 in the same manner as in the previous example), and the width of the track 10 becomes TP (not shown).

The steps (a) to (→ in the previous section) are repeated while the tape is running, and as a result, the magnetization pattern on the magnetic tape becomes a guard panless state with a track pitch TP as shown in FIG. This is a method of recording video signals according to the present invention.Hereinafter, in this embodiment, which will be explained regarding re-transmission, recording and reproduction are performed by the same head in order to reduce the number of heads attached to the rotating cylinder.Therefore,
The track width of the playback head is T. Therefore, even when the track is accurately tracked (FIG. 2), the track overlaps the adjacent track by an amount W. However, in the present invention, since azimuth recording can be performed at an azimuth angle of θ-90° where the reproduction azimuth loss is maximum, there is no crosstalk from W1, and the gap of the reproduction head deviates from the recording track on the tape to be reproduced. Unless otherwise specified, the reproduction output will not decrease and a constant SN ratio (signal-to-noise ratio) can be obtained. In other words, the tracking margin of the playback head is at least Tw-Tr
)/2. Although four rotating magnetic heads including two erasing heads are used in this embodiment, the same effect can be obtained even if more rotating magnetic heads are used. Furthermore, since the signal output depends on the magnetic properties of the magnetic tape in the recording direction of the magnetic head, the magnetic heads 2 and 3 have in-plane isotropic magnetic properties so that there is no difference in signal output between the video recording magnetic heads 2 and 3. It is better to use magnetic tape.

Furthermore, the signal to be recorded is not limited to the above-mentioned video signal, and may be any other signal. That is, by changing the information signal to be recorded, the present invention can be carried out using an external storage device for a computer, a tape recorder for audio recording, or the like.

Effects of the Invention As described above, according to the present invention, high quality signals can be recorded without guard panning at a large azimuth angle using a magnetic head having a track width wider than the track width recorded on a magnetic tape. This has the effect of eliminating crosstalk from adjacent tracks due to head tracking deviation during reproduction, and solving tracking accuracy problems associated with narrower recording tracks.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are perspective views of a recording/reproducing mechanism section of an embodiment of the present invention and an explanatory diagram showing the recording process, and FIG. 2 is a recording pattern on a magnetic tape of an embodiment of the present invention. Figures 3 and 4 are explanatory diagrams showing recording tracks on a conventional magnetic tape, and Figures 5(a) to (Φ are graphs of calculation results of the amount of crosstalk from adjacent tracks.1. . . . Magnetic tape, 2. 3 . . . Magnetic head for video recording, 4, 5 . . . Erase head, 6.
7...Guide post, 8...Rotating cylinder, 9, 10...Figure Recording track.

Claims (3)

[Claims] (1) A magnetic tape is wound around the outer periphery of a tape guide drum having at least two erasing heads among a plurality of rotating magnetic heads and is run, and the rotating magnetic head is scanned in a direction diagonal to the tape running direction. The helical scanning magnetic recording device is a helical scanning magnetic recording device in which the erasing head erases a portion including an end of the first recording track on the magnetic tape recorded by the first rotating magnetic head; The second rotating magnetic head has a mechanism for forming a second recording track without overlapping the first recording track, and the recording track width on the magnetic tape is narrower than the track width of the rotating magnetic head. Features of magnetic recording device. (2) The magnetic recording device according to claim (1), wherein the angle formed by the magnetization patterns of two adjacent recording tracks on the magnetic tape is 80° or more and 100° or less. (3) The magnetic recording device according to claim (1), wherein a medium comprising a magnetic layer having isotropic magnetic properties in the plane of the tape is used as the material of the magnetic tape.