JPS6222224A - Magnetic disc device - Google Patents

Abstract

PURPOSE:To improve the recording density of a magnetic disc and the positioning accuracy of a magnetic head by using a hologram optical element of a photo induction type magnetic head where a magnetic head and a hologram optical element are incorporated so as to access a desired track thereby applying recording and read. CONSTITUTION:A laser light irradiated from a light emitting diode 5 built in the hologram element 50 of the optical induction type magnetic head 60 incorporating the magnetic head 3 and the hologram optical element 50 is irradiated in a guide groove 11 of the optical induction type magnetic disc 10 via a mirror 6 and a condenser lens 7. Its reflected light goes reversely, is incident in a differential photo diode 9 to discriminate the deviation between the center 'O' of the laser light and a center 'O' of the guide groove 11. The magnetic head 3 is activated in on-track state to apply recording/read to the track. Thus, the recording density of the magnetic disc 10 and the positioning accuracy of the magnetic head 3 are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The magnetic disk device of the present invention has a structure in which tracks are directly accessed by a light-guided magnetic head in which a hologram optical element and a magnetic head are integrated.

Therefore, with this device, the recording density of the magnetic disk substrate and the reliability of access operations can be greatly improved.

[Industrial application field]

The present invention relates to an improvement in a magnetic disk device, and more particularly to a magnetic disk device that accesses a desired track using a hologram optical element integrated with a magnetic head.

Recent magnetic disk drives tend to be faster and smaller.

For this reason, there is a strong demand for the development of a magnetic disk device with the ability to directly access a desired track.

The present invention simplifies the structure of the device and improves the reliability of access by employing a magnetic head guidance system using a known hologram optical element for optical disks.

[Conventional technology]

FIG. 5 is a side view of main parts showing the main structure of a conventional magnetic disk device.

As shown in the figure, a conventional magnetic disk device has a recording magnetic disk 2 and a positioning magnetic disk 2a fixed to a spindle shaft 1 that rotates in the direction of the arrow, and a position facing each of these disks 2, 2a. The head drive mechanism 4 guides the magnetic data head 3 and the magnetic servo head 3a arranged on the disk to a desired track on the disks 2, 2a according to commands from the head drive control section 20.

The procedure for the induction will be shown below.

(2) To the magnetic servo, the RAD 3a obtains required positioning information from the positioning disk 2a and transmits it to the drive control section 20.

■The drive control unit 20 controls the head drive mechanism 4 based on the information.
and moves the magnetic data head 3 in the direction of arrow B-8' to guide it onto a desired track on the recording magnetic disk 2.

The disks 2 and 2a are both coated with a magnetic film for recording information on a flat metal plate, for example, an aluminum substrate, address information is recorded on the recording magnetic disk 2, and positioning disk 2a is coated with a magnetic film for recording information. It is well known that clock signals and servo signals are recorded.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional magnetic disk drive, the recording magnetic disk and the positioning magnetic disk are placed in different locations. Therefore, the track width must be increased to account for this error.

■Since the clock signal is written magnetically, if there is a defect in the magnetic film, the demodulation circuit will be disturbed and a wide range of errors will occur.

■Reproducing magnetically written signals to create “1” and “0”
Since all of the discrimination circuits are controlled, excessive quality is required for the reproduced signal.

For these reasons, it has become difficult to significantly improve the recording density, or to narrow the track width any further.

Incidentally, the track width of current magnetic disks is limited to about 30 μm.

The present invention has been made in order to solve these problems and provide a magnetic disk device that can significantly improve recording density.

[Means for solving problems]

The above problem is solved by a light-guided magnetic head in which a magnetic data head and a hologram optical element are integrated, and a light-guided magnetic disk substrate in which a track groove is formed on an information recording zone. This problem is solved by providing the magnetic disk device of the present invention in which a desired track is accessed by an element and recording and continuous data are performed.

[Effect]

The magnetic disk device of the present invention includes a light-guided magnetic disk substrate in which track grooves characterizing addresses are formed adjacent to each magnetic recording layer, and a hologram optical element for optically accessing the track grooves. The structure includes a light-guided magnetic head consisting of:

The desired trunk groove is detected by a hologram optical element, and recording/reading is performed by a magnetic head integrated with the hologram optical element, so track access accuracy is dramatically improved compared to conventional methods. , Access errors do not occur even if the trunk width is narrowed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a side sectional view showing the structure of a light-guided magnetic head in which a magnetic head and a hologram optical element are integrated.

- As shown in the figure, the optically guided magnetic head 60 of the present invention has a structure in which the magnetic data head 3 and the hologram optical element 50 are integrated.

FIG. 2 (Al is a perspective view of the main part for explaining the principle of accessing the center position of the track groove.

As shown in the figure, a track guide groove 11 adjacent to each magnetic recording layer 12 in the circumferential direction is formed in the optically guided magnetic disk substrate 10 according to the present invention, and a hologram element 50 accesses the center 0 of the trunk guide groove. It is configured to do this.

The principle will be described below.

Light emitting diode 5 built into hologram optical element 50
Laser light 8 emitted from
0 trunk guide groove 11 and its surrounding area are irradiated in a limited manner.

Then, the reflected light 8'' of the laser beam 8 that has irradiated the track guide groove 11 returns in the opposite direction to the forward path, and is directed to the differential photodiode 9.
The deviation between the center 0'' of the laser beam 8 and the center 0 of the track guide groove 11 is determined.

FIG. 2 (bl is a side sectional view showing one embodiment of a hologram optical element.

The elliptical light emitted from the semiconductor laser 13 is transmitted to the polarization separation resist hologram 14. The light passes through a hologram lens 15 and a quarter wavelength plate 16 and is focused onto the disk substrate 10.

14 is an element that can change the course of light depending on the polarization direction of the light, and corresponds to a conventional polarizing beam splitter.

Reference numeral 15 corresponds to an objective lens, and since light is incident obliquely here, it also has a circularity correction effect.

The polarization direction of the reflected light from the disk substrate 10 is rotated by 90 degrees by the wavelength plate 16, and the direction is changed to the direction of the two-split photodetector 18 by 14 elements. On the other hand, since these hologram elements utilize a diffraction effect, there is always some zero-order light that passes through the hologram element, and this passing light is received by the two-split photodetector 17.

Since the two-split photodetector 17 is placed in the far field, it is possible to detect a tracking signal in a tracking detection direction called the Pu5h-Pull method. Furthermore, since a focus error signal can be obtained from the other two-split photodetector 18, abnormalities such as head crashes can be detected using this signal.

The clock signal can be obtained from the sum signal of the two-split photodetectors 17 and 18.

By integrating the above 13 to 18, 1.5 Xl,
Since a very small size of about 5 x 1.5 mm is possible, it can be incorporated into a magnetic head.

Figure 3 is a diagram showing the output pattern of the differential photodiode, (a) shows the pattern when the optical axis is on the left, (b) shows the pattern when on-track, and (C1 shows the pattern when the optical axis is on the right). ing.

Since the difference in light intensity shown in FIG. 3 corresponds to the track deviation, the error in track positioning is guided to the head drive control unit 20 in FIG. The situation will be corrected.

When the on-track state is established in this way, the magnetic data head 3 shown in FIG. 1 operates to perform recording/reading on the track.

The width of the guide groove 11 is preferably about 6 to 10 times the groove depth.

Further, the guide groove may be provided at the center of the trunk where the magnetic signal is written, or may be provided at an intermediate portion between the tracks.

FIG. 4 is a diagram showing an example of a track groove formed on a light-guided magnetic disk substrate, in which (a) is a perspective view of a main part;
(b) is an AA' cross-sectional view.

A magnetic film is coated on this substrate, and information is recorded by a magnetic head 60 shown in FIG.

As shown in FIGS. 1A and 2B, a track guide groove 11 is formed on the substrate surface 12 of the optically guided magnetic disk substrate 10, and the track guide groove 11a has a depth of me/8. Focus 11 for address information with depth λ/4
b is formed.

Tracking signals are obtained from these grooves 11a, and address signals are obtained from pits llb.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic disk device according to the present invention will be specifically described below with reference to FIGS. 1 to 4.

A groove with a zero width of approximately 0.8 μm is formed on the optically guided magnetic disk base Fi.
, 10, and this is used as the track groove 11.

(2) A servo signal layer having a depth of approximately λ/8 (λ is the wavelength of the laser beam, and therefore approximately 0.07 μm in this case) is formed in the track groove 11.

(2) Similarly, an address signal layer with a depth of about λ/4 is formed in the track groove 11.

(2) Similarly, a hole is formed in the trunk groove 11 to form a clock signal layer.

(2) Coat a magnetic recording layer (preferably 0.1 μm or less) thereon.

(2) By detecting the interference effect that occurs when the track groove 11 is irradiated with a laser beam, the track position deviation is detected as described above.

According to the above method, track positioning can be performed with an accuracy of 0.1 μm or less.

In this way, according to this embodiment, at least 3
It becomes possible to reduce the track width, which used to be 0 μm, to several μm or less.

Another positioning method is to form a pit (unevenness) with a depth of λ/4 at the beginning of each sector and take a track deviation signal from there (a well-known method for optical discs), but the positioning accuracy is low. This method is approximately the same as the above method.

If track access is to be performed by counting the number of times the groove is crossed, a method in which grooves with a depth of λ/8 are formed over the entire surface of the disk would be superior.

In addition, since the present invention continuously forms unevenness for clock signals on all tracks on concentric circles, this is optically reproduced to create a clock signal, and data is written magnetically based on this clock. , When reproducing this data, the reference clock is also generated by optically reproducing the unevenness. The unevenness is written at a single frequency, so even if the unevenness is chipped or the laser reflective film (in this case, the magnetic film for magnetic recording) is chipped, the clock will remain stable unless the chip is extremely large. can be obtained. Therefore, (a) the adverse effect of clock signal jitter (noise thick) due to insufficient S/N is greatly reduced, so that the recording density can be improved. -m = In the current state-of-the-art magnetic disk, the influence of noise jitter is 50% of the clock width used to distinguish between 1 and O.
It has become more than that.

(b) Since the phase of the magnetically written signal and the concavo-convex pits (clock) are completely the same, the phase shift peculiar to magnetic recording that occurs during reproduction can be accurately corrected.

(C) Since the clock is stably obtained, even if there is a defect, its influence will not be spread over a wide area.

〔Effect of the invention〕

As explained in detail above, the magnetic disk device of the present invention significantly improves the recording density of the magnetic disk and the positioning accuracy of the magnetic head by introducing a light-guided magnetic head that integrates a hologram optical element and a magnetic head. This is a very effective way to do so. Of course, this technology can also be applied to magnetic tape.

[Brief explanation of drawings]

Fig. 1 is a side sectional view showing the structure of a light-guided magnetic head in which a magnetic head and a hologram optical element are integrated; A perspective view, FIG. 2 (bl is a side sectional view showing an example of the configuration of a hologram optical element, FIG. 3 is a diagram showing an output pattern of a differential photodiode, and FIG. 4 is a diagram showing a configuration of a hologram optical element formed on a light-guided magnetic disk. Fig. 5 is a side view of main parts showing the main configuration of a conventional magnetic disk device. In the figure, 1 is a spindle shaft, 2 is a recording magnetic disk,
a is a positioning disk, 3 is a magnetic data head, 3a
is a magnetic servo head, 4 is a head drive mechanism, 5 is a light emitting diode, 6 is a mirror, 7 is a condenser lens, 8 is a laser beam, 8゛ is a reflected light, 9 is a differential photodiode, 10 is a light-induced magnetism Disk substrate, 11 is a track guide groove, ll
a is a reflective layer, llb is a non-reflective layer, 12 is a substrate surface, 13
14 is a semiconductor laser, 14 is a polarization separation resist hologram,
15 is a hologram lens, 16 is a 174 wavelength plate, 17.
18 is a two-split photodetector, 20 is a head drive control unit, 50
denotes a hologram optical element, 60 denotes a light-guided magnetic head, and O
indicates the center of the track groove, and 0゛ indicates the optical axis of the laser beam. Book 1 (2) Figure 3 1 Milov "Ram Street"
b) 1 lazo 7 bottles - example figure 4

Claims (1)

[Claims] A magnetic disk device comprising a magnetic disk substrate and a magnetic head, the device comprising: a light-guided magnetic head in which a magnetic data head and a hologram optical element are integrated; a light-guided magnetic disk substrate having track grooves formed on the zones, a desired track on the light-guided magnetic disk substrate is accessed by the hologram optical element, and recording/reading is performed by the magnetic data head. A magnetic disk device characterized in that it is configured to perform