JPS6028082A - Tracking method of magnetic head for floppy disk - Google Patents

Abstract

PURPOSE:To detect simply and with high accuracy both the direction and degree of a tracking shift by giving vibrations of a fixed cycle and a fixed amplitude to a head assembly and measuring the phase and amplitude of an output signal produced by an erasion head for correction. CONSTITUTION:An R/W head 1 and a correcting erasion head 2 are fixed in a body by a resin mold 3 to form a head assembly 4. The writing is carried out at a gap 1a of a head 1, and a track written on a disk in a wide width receives a correction of DC demagnetization at gaps 2a and 2b of a subsequent head 2 and is trimmed in the track width corresponding to the width of a cut groove 2c. The track set in a fixed width in such a way is read again at the gap 1a. Then vibrations of a prescribed cycle and a prescribed amplitude are given to the assembly 4 via a wire for shift of the assembly, and the phase and amplitude are measured for an output signal produced by a head 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting tracking deviation when reading with a magnetic head for a floppy disk.

Magnetic heads for floppy disks generally use the same read/write head (hereinafter referred to as
In order to accurately correct the track width written on the disk, a correcting erase head is used. Then, when writing is performed by the R/W head, the written track width is subsequently corrected by the correction erase head to obtain a track of a constant width. When reading a track of a constant width written on a disk in this way, accurate tracking is required and the track must be set at the correct position of the R/W head.

By the way, conventional magnetic heads for floppy disks have not been equipped with a mechanism to detect tracking deviations during reading, and the tracking accuracy currently depends solely on the mechanical positioning accuracy of the drive mechanism. be.

However, as the recording density of F4P discs has become higher today, narrower track widths are required, and tracking has become more accurate than ever before. Without a detection mechanism, accurate reading becomes difficult (in other words, as the track width becomes narrower, slight deviations in tracking that did not previously pose a problem will become a hindrance to reading. A highly accurate detection method that can catch such deviations is essential, and then a mechanism to correct deviations, a so-called tracking servo mechanism, must be installed.Therefore, for example, it may be possible to install a new head for detecting tracking deviations. However, manufacturing and arranging such a detection head requires especially strict dimensional and positional accuracy, which complicates the work in manufacturing the magnetic head and is not a suitable method.

The purpose of the present invention is to solve the problems of the prior art and to provide a magnetic disk for floppy disks that can detect the direction and magnitude of tracking deviation with high precision by newly installing special parts such as a detection head. To provide a head tracking method.

To achieve this objective, the present invention integrally forms a read/write head and an erase head for track width correction, and uses the integrally formed head assembly for erasing a constant cycle in a direction perpendicular to the track. It is characterized in that tracking deviations are detected using the output signal of the head.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic plan view of a magnetic head for a floppy disk 2, in which an R/W head 1 and a correction erasing head 2 are fixed together by a resin mold 3, and a head assembly 4 is shown.
is formed. The R/W head 1 is provided with a spacing gap 1a and a notched groove 1b%IC, and the correction erasing head 2 is provided with spacing gaps 2a and 2b and a notched groove 2c.

Next, the operation of the floppy disk magnetic head constructed as described above will be described.

First, writing is performed using the head gap 1a of the R/W head 1.
The track on the disk written in the wide width direction advances in the direction of arrow A in FIG. Then, the head gearing 2a of the subsequent correction erasing head 2,
At step 2b, the track width is corrected by DC demagnetization and trimmed to a track width corresponding to the width of the notched groove 2C. FIG. 2 shows this situation. In FIG. 2, the solid line indicates the magnetically recorded track width, and the dotted line indicates the hend assembly 4 of FIG. 1.

Reading the tracks aligned to a certain width in this way is
Writing is performed again in the head gap 1a of the R/W head 1, and the direction of track movement is also the same as during writing. Note that during reading, the correction erasing head 2 stops demagnetizing. Then, the head assembly is moved to the head assembly 4 via a steel wire (not shown) for moving the head assembly in the direction of arrow B in FIG. Tracking deviation can be detected by applying vibration and measuring the phase and amplitude of the output signal generated by the correction erasing head 2 at this time.

That is, if tracking is performed accurately, as a result of the above-mentioned forced vibration, the head gaps 2a and 2b of the correction erasing head 2 will alternately dig into the track by a maximum of 20 μm, as shown in FIG. A sine wave waveform is obtained. On the other hand, when the track position is shifted to the right in the traveling direction, the head gap 2a cuts into the track less, resulting in a waveform in which the positive phase of the sine wave is collapsed, as shown in FIG. 3 (Bl). If the track position deviates to the left in the traveling direction, the head gap 2b bites into the head gap 2b less, so that a waveform in which the negative phase of the sine wave is collapsed as shown in FIG. 3 (Q) is obtained.

Finally, by detecting the phase of the output signal, the direction of tracking deviation can be determined. The smaller the width of the head gap 2a or 2b into the track, the lower the output generated therein. Therefore, by measuring the amplitude of the collapsed portion of the waveform, the magnitude of the tracking deviation can be accurately determined.

Once the direction and magnitude of the tracking deviation can be detected from the phase and amplitude of the output signal, the deviation can be corrected accordingly to perform accurate tracking.

In the case of this embodiment, the amplitude of the forced vibration is set to ±20 μm, so that the track does not close to the head gap 1a during the vibration.
There are no rips protruding from the lens, and the effects of vibration do not appear on readings.

Further, the period and amplitude of vibration can be changed as appropriate according to the width of the head gap, the number of revolutions of the disk, etc., within a range that does not interfere with reading.

As explained above, according to the present invention, vibrations of a constant period and constant amplitude are applied to the head assembly, and the phase and amplitude of the output signal generated by the correction erasing head are measured. It is possible to simultaneously detect the direction and magnitude of tracking deviation easily and with high precision without installing new special parts.

[Brief explanation of the drawing]

The drawings show an embodiment of the method of the present invention, and FIG. 1 is a schematic plan view of a magnetic head for a floppy disk, and FIG. 2 is a schematic plan view showing how the magnetic head shown in FIG. 1 corrects the track width. FIG. 3 is an explanatory diagram qualitatively showing the waveform obtained from the correction erasing head during head assembly vibration. 1... Read/write head, 2...
- Erasing head for correction, 4...Head assembly. Figure 1 $28 Figure 3

Claims (1)

[Claims] A reading/writing head and an erasing head for track width correction are integrally formed, and the integrally formed head assembly is vibrated at a constant period and with a constant amplitude in a direction perpendicular to the track, and during this vibration, the correction head is A tracking method for a magnetic head for a floppy disk, characterized in that a tracking deviation is detected using an output signal of an erasing head.