JPS6299938A - Magnetooptical recording and reproducing device - Google Patents

Abstract

PURPOSE:To apply easily tracking control by using a refractive index distribution type lens and a polarization plane maintaining fiber so as to fit a laser light supply source and a detection optical system at a position separated from a main magnetic pole. CONSTITUTION:A thin film main magnetic pole 4 is supported to one end of a cantilever 10, a laser light is led from the other end of the cantilever 10 via the polarization plane maintaining fiber 9 and the laser light is irradiated to the tip of the main magnetic pole through the optical system including the refractive index distribution lenses 8, 6. Then the reflected or transmitted laser light is extracted at the outside of the cantilever via the original optical system and fiber and fed to a photodetector. thus, the part in contact with a medium is made light to facilitate the movement of the cantilever supporting the main magnetic pole and the tracking control is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a magnetic/optical recording and reproducing apparatus for reproducing perpendicular magnetic recording media using a laser beam, and particularly relates to an auxiliary magnetic pole excitation type perpendicular recording/reproducing apparatus. This relates to the structure of a reproducing means using a magnetic head.

BACKGROUND OF THE INVENTION One type of perpendicular magnetic recording on a magnetic recording medium is to arrange a thin main magnetic pole and an auxiliary magnetic pole facing each other on both sides of the medium, and to excite the auxiliary magnetic pole with a recording signal. As is well known, perpendicular magnetic recording can increase the heating degree and areal density compared to conventional longitudinal longitudinal magnetic recording. Although the areal density can be improved by narrowing the width of the recording track, it is known that the reproduction output, that is, the C/N ratio, deteriorates accordingly in the case of magnetic reproduction.

Therefore, attempts have been made to narrow the track width and increase the C/N. As a method for this, it has been considered to extract changes in the magnetization direction as changes in light during reproduction. In that case, the appropriate light to be used is a laser beam, which is focused on the tip of the thin-film main pole, and the reflected or transmitted light from the main pole surface is extracted through an optical system and sent to a photodetector to generate an electrical signal. Convert to

At the tip of the main pole, a magnetization distribution appears that corresponds to the magnetization information on the magnetic recording medium that is in contact with it, that is, the polarity of the recording bit. The reflected light of the laser beam obtained from the magnetization distribution (d) The transmitted light is given a rotation of the plane of polarization based on the magneto-optic effect called the Kerr effect or the Faraday effect. It senses strength and weakness and converts it into an electrical signal.

Therefore, by recording with the perpendicular magnetization method, a thin 1μ main magnetic pole is used for linear density, so laser light recording (1μ
m/bit) Higher value (o, 1 μm/bit)
In order to increase the C/N during reproduction, the track density, that is, the track width, is set to a value similar to that of optical recording (1,6
6. Problems to be Solved by the Invention However, this type of magnetic/optical head device that has been conventionally considered is Since the main magnetic pole side has a structure in which the means for irradiating the laser beam is integrated, it is not only large but also heavy, making it difficult to move, and the tracking servo cannot be fully implemented, so it is not yet suitable for practical use. Ta.

Therefore, an object of the present invention is to provide a configuration of a magnetic/optical head device to which tracking servo can be easily applied.

Means for Solving the Problem) This invention arranges an excitation type auxiliary magnetic pole on one side of a perpendicular magnetic recording medium, and arranges a thin film main magnetic pole on the other side of the medium corresponding to the auxiliary magnetic pole, Perpendicular magnetic recording is performed on the medium by exciting the auxiliary magnetic pole with a recording signal, and during playback, a laser beam is irradiated to the tip of the main magnetic pole, and changes due to the magneto-optic effect that appear in the reflected or transmitted light from the tip are optically detected. Magnetic /
It is applied to optical recording and reproducing devices. That is, a thin film main pole is supported at one end of the cantilever, a laser beam is guided from the other end of the cantilever via a polarization maintaining fiber, and the laser beam is directed to the main pole through an optical system including a gradient index lens. The feature is that the tip is irradiated, and the reflected or transmitted laser light is taken out of the cantilever via the original optical system and fiber and supplied to a photodetector.

According to the magnetic/optical recording and reproducing device of the present invention, a thin film main pole is attached to a cantilever, and a light source of a laser beam that irradiates the tip of the main pole and a photodetector that detects reflected light or transmitted light are connected from the cantilever. The polarization maintaining fibers are installed at separate positions, and the polarization maintaining fiber is used as a laser beam beam between the laser beam and the laser beam. As a result, the portion in contact with the medium has become lighter, making it easier for the cantilever that supports the main pole to move, making it possible to perform tracking control.

Embodiments Examples of the present invention will be described below with reference to the drawings. FIGS. 1 to 3 are diagrams showing the main magnetic pole and the cantilever.

Reference numeral 1 denotes a disk made of a polyester film, on one surface of which a sputtered thin film 2 of, for example, a Co--Cr perpendicular magnetic recording medium is formed. One side of this medium 2,
That is, an excitation type auxiliary magnetic pole 3 is arranged on the polyester film 1 side, and the tip of a thin film main magnetic pole 4 having a magnetic anisotropy such as Co-Zr-Ta is arranged so as to be in contact with the other side. has been done. The main magnetic pole 4 is surrounded by a glass holder 5. A gradient index lens 6 is in contact with the other end of the main pole 4, and a mirror 7 and a gradient index lens 8 are provided above it. The refractive index gradient lens 6.8 is a cylindrical lens that functions to condense incident light according to a predetermined refractive index distribution.

In the case of the lens 6, the laser beam incident through the mirror 7 is focused on the tip of the main magnetic pole 4, but this type of lens id rs
It is commercially available as elfoc J (trademark). Further, the lens 8 is arranged to inject reflected light into a polarization-maintaining fiber 9 that transmits the incident light while maintaining its polarization plane. The polarization maintaining fiber 9 enters the cantilever 10 through a hole at one end, is taken out from a hole at the other end, and is guided to an optical system to be described later. cantilever 1
0 supports an optical block including a main magnetic pole 4 at one end, and is supported at the other end by a neutral position holding damper 11 on a head carrier (not shown) having a well-known structure that linearly drives the disk. A permanent magnet 12 is attached to the end further than the damper 11, and the cantilever 10 is gripped by the excitation coil 13, and the main magnetic pole 4
can move horizontally on the disk surface and in a direction substantially perpendicular to the recording track 15. In other words, it constitutes a tracking control mechanism that accurately traces a predetermined portion of the recording track 15 during reproduction.

Although the cantilever is omitted in Figure 4,
Understand the flow of laser light. 20 is a laser diode, 21 is a collimator lens, 22 is a beam splitter,
23 is an IA wavelength plate, 24 is a single lens, 25 polarizing beam splitters, and 26 and 27 are photodetectors, which are of well-known construction. A coupling lens 14 is provided between the beam splitter 22 and the polarization maintaining fiber 9.

During recording, when the auxiliary magnetic pole 3 is excited with a recording signal, two perpendicular magnetic recording media magnetized to one polarity in advance,
The magnetization polarity is reversed according to the signal. In this case, in the recording signal, as a tracking signal, signals of different frequencies f, , f, which are alternately switched every other rotation of the disk, are included in one information signal component 16 as shown in the spectrum of FIG.
is mixed into the low range. Then, as shown in FIG. 3, recording tracks 15 are magnetized and formed on the medium 2, each of which alternately contains fh and f- components.

During reproduction, the laser beam emitted from the laser diode 2o passes through the collimator lens 21, beam fritter 22, coupling lens 14, polarization maintaining fiber 9, gradient index lens 8, mirror 7, gradient index lens The beam is irradiated onto the tip of the thin film main pole 4 which contacts the medium 2 through the beam 6 .

The magnetization direction of the tip of the main pole 4 changes due to the leakage magnetic field from the medium 2. Therefore, when a linearly polarized laser beam is focused on the tip, the reflected light from the thin-film main magnetic pole 4 or the transmitted light has a rotation of the plane of polarization based on magneto-optic effects such as the Kerr effect or the Faraday effect. This reflected light and transmitted light are transmitted through a gradient index lens 6, a mirror 7, a gradient index lens 8, a polarization maintaining fiber 9, a coupling lens 14, a splitter 22, a dedicated wavelength plate 23, and a single lens 24. , are transmitted to the photodetectors 26 and 27 via the polarization beam splinter 25 and converted into electrical signals.

The photodetectors 26 and 28 sense the rotation of the plane of polarization of the incident light as the strength and weakness of the light, and the electrical signals converted by each are given to the differential amplifier 32 via the corresponding amplifiers 3() and 31. , the output thereof is converted into an RF signal and is applied from a terminal 33 to a recording information reproducing circuit. On the other hand, a part of the RF multiplied signal is given to a bandpass filter 34.35, and the frequency f
, and f2 signals are taken out and rectified circuits 36 and 37
is converted into each DC component by Each DC signal is applied to a differential amplifier 38, taken out from a terminal 39 as a tracking error signal, and used as a tracking control signal to excite the 11-1 excitation coil 13.

As described in detail, the magnetic/optical recording and reproducing apparatus of the present invention performs perpendicular magnetic recording on a magnetic recording medium, and during reproduction, irradiates the tip of the thin film main pole used during recording with a laser beam. The reproduction signal is obtained by detecting the magneto-optic effect of reflected light or transmitted light, and therefore there is no need to prepare a head exclusively for reproduction.

In addition, by using a gradient index lens and polarization maintaining fiber, the laser light source and the optical system for detecting reflected light and transmitted light can be installed in a position separated from the main magnetic pole. By reducing the side weight as much as possible, tracking control can now be easily performed by supporting the main magnetic pole with a cantilever.

[Brief explanation of drawings]

FIG. 1 is a front view showing the head portion of a magnetic/optical recording/reproducing device according to an embodiment of the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a perspective view thereof, and FIG. 4 is a configuration of the optical system. FIG. 5 is a block circuit diagram of a signal reproducing system, and FIG. 6 is a frequency spectrum diagram. 2... Perpendicular magnetic recording medium, 3... Excitation type auxiliary magnetic pole, 4... Thin film main magnetic pole, 6 and 8... Gradient index lens. ,7...
... Mirror, 9 ... Polarization maintaining fiber, 10 ...
・Cantilever, 20... Laser diode, 26 and 27
...-photodetector. Patent Applicant Nihon Toki Home Electronics Co., Ltd. Figure 1 Figure 2

Claims (2)

[Claims] (1) An excitation type auxiliary magnetic pole is placed on one side of a perpendicular magnetic recording medium, a thin film main magnetic pole is placed on the other side of the medium corresponding to this auxiliary magnetic pole, and the auxiliary magnetic pole is excited with a recording signal. By doing so, perpendicular magnetic recording is performed on the medium, and during reproduction, a laser beam is irradiated at the tip of the main magnetic pole, and a photodetector detects a change based on the magneto-optic effect that appears in the light reflected or transmitted from the tip. In a magnetic/optical recording and reproducing apparatus which obtains a reproduced signal using irradiating the tip of the thin film main pole through an optical system including a distributed lens, and taking out reflected or transmitted laser light out of the cantilever via the optical system and polarization maintaining fiber and supplying it to the photodetector. Characteristic magnetic/optical recording and reproducing device. (2) The recording signal component has a spectrum obtained by mixing a signal having a predetermined frequency as a tracking signal with an information signal, and the tracking signal is separated and extracted from the reproduction signal to perform tracking control of the main magnetic pole. A magnetic/optical recording/reproducing device according to claim 1, characterized in that: