JPH03203841A - Optical disk device - Google Patents

Abstract

PURPOSE:To perform the position control of a high precision in the track direction by controlling positions of an optical head part and an applied magnetic field part in the track direction by the same driving. CONSTITUTION:An optical head part 101 which is so arranged that a convergent beam 117 is placed on the transparent substrate side of a magneto-optical recording medium 102 having a perpendicularly magnetized film on the transparent substrate consists of a light source 106, a lens system 103, a signal detecting optical system, and a servo signal optical system. An applied magnetic field member 110 consists of an applied magnetic field generating coil 111 and is placed to face the optical head part 101 with a medium 102 between them and is so constituted that a magnetic field is applied to the medium 102, and the coil 111 is connected to a driving circuit, and the magnetic field can be inverted with a high frequency. In this case, the optical head part 101 and the applied magnetic field member 101 have no influences when being driven to the medium 102 and are joined in the part where they can scan approximately linearly on the medium though being rotated. Thus, the precision of the position control in the track direction is improved.

Description

[Detailed description of the invention] It is related to optical disc devices that use formulas.

[Conventional technology]

The magneto-optical recording medium is formed by having a perpendicular magnetization film 3 on a light-transmitting substrate 2, as shown in FIGS. 4 and 5, for example. Information is recorded on this by the magnetic field modulation method shown in FIG. There is an optical modulation method shown in FIG. In recording using the magnetic field modulation method, a laser beam 4 is focused on the perpendicularly magnetized film 3 through a lens system 5 to locally heat the recording part, and a magnetic field applying means 6 is applied to the heated part to cause the perpendicularly magnetized film to be heated. On the other hand, magnetic fields in opposite directions according to recording information "0" and "1" in the perpendicular direction are applied to the film surface to form magnetic domains, that is, recording pits, due to magnetization in this direction. Such recording can be performed on a magneto-optical recording medium using a continuous servo system in which a pre-group (guide groove) is formed, or on a magneto-optical recording medium using a sample servo system that does not rely on pre-groups.

Reading out records from a recording medium recorded in this way is done by simply lowering the power of the laser beam used during recording than that used during recording, and the result is "0" or "1".
The recorded information pits are read out based on the difference in Kerr rotation IK between these information pits.

In this way, the magnetic field modulation recording method uses the external magnetic field obtained by the coil 6, which is a magnetic field applying means, to generate recorded information "0" and "1".
Information is recorded by inverting the disc according to the situation.

On the other hand, in the optical modulation method, as shown in Fig. 5, the external magnetic field obtained by the permanent magnet 7 etc. is kept constant during the recording operation, and the laser beam 4 is irradiated or irradiated depending on the recording information "0" or "1". Information is recorded by changing the intensity of the laser beam (actually, by changing the intensity of the laser beam).

In FIG. 5, 9 is a protective coating, 10 is a protective layer, 11 is an insulating layer, and 8 is a slider for moving the permanent magnet 7 in the tracking direction of the magneto-optical recording medium 1.

Normally, in this type of magneto-optical recording, the magnetic field modulation method or optical modulation method requires tracking control of the recording information magnetic field by magnetization perpendicular to the perpendicular magnetization film, similar to laser beam tracking control, and the recording density Improvement, S/
In order to improve the N ratio, it is preferable that the magnetic domain has a minimum size, and currently the size is 1μ. Furthermore, in order to form a magnetic domain of about 1 μm, it is necessary to align the tracking control of the laser beam and the applied magnetic field at the same position and with high precision.In most cases, application is performed by strong magnetic force using the magnetic field distribution, and the mechanism of the applied magnetic field and the medium In the prior art, the position control of the laser beam in the tracking direction and the position control of the applied magnetic field were performed using separate drive systems.Furthermore, in the optical modulation method, the applied magnetic field was controlled by a permanent magnet or the like to control the position of the laser beam. It was constructed so that it could apply in all the scanning directions.

When controlling the positions of the laser beam and the applied magnetic field in the tracking direction using separate drive systems, their phases may be different from each other, and this phenomenon becomes more pronounced as the seek speed increases.

The present invention aims to improve the accuracy of controlling the position of a laser beam and an applied magnetic field in the track direction in magneto-optical recording, and provides a mechanism capable of high-speed access and recording.

In the present invention, in order to achieve high precision position control of the laser beam and the applied magnetic field in the track direction, a light source and a lens system,
The optical head section, which has a signal detection optical system and a servo signal detection optical system, and the applied magnetic field section are made of the same material, and the convergent laser beam section and the applied magnetic field section are composed of a rotating support mechanism that scans in the track direction. This is an information recording and reproducing mechanism characterized by simultaneous scanning of magnetic fields.

[For production]

As described above, in the mechanism of the present invention, the optical head section and the applied magnetic field section are made of the same material, and the optical head section and the applied magnetic field section are arranged to face each other and the magneto-optical recording medium is placed between them, so that scanning in the track direction of the medium is possible. The convergent laser beam part and the applied magnetic field part are scanned in a nearly straight line by supporting one point on the machine member.

By constructing the optical head section and the applied magnetic field section from the same material, track direction control, high-speed access, and a highly accurate positional relationship are possible without generating phase differences between them during recording.

Furthermore, the resistance of the carriage system, which is scanned by a rotating mechanism supported at one point, is reduced, and high-speed recording becomes possible.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention.

The configuration and functions of the information recording and reproducing mechanism of this embodiment will be explained below with reference to the drawings.

Magneto-optical recording medium 102 having a perpendicular magnetization film on a transparent substrate
The optical head section 101 is composed of a light source 106, a lens system 103, 105, a signal detection optical system, and a servo signal optical system. is located on the optical head. Furthermore, there is a drive system 113 below the optical head section 101, including a coil 114, a magnet 115, a yoke 116, and a drive system 113.
It is configured so that a linear motor consisting of the following can be attached. By passing a current through this coil 114, a magnetic force is generated, which is converted into light by the influence of the magnet 115, so that the door portion 101 can be driven in a direction perpendicular to the drawing.

Further, the applied magnetic field member 110 includes the applied polishing field generating coil 11.
1 and is located on the opposite side of the optical head member 101 and the medium 102 with the medium 102 in between, and is configured to generate an application 112 to the medium 102. Furthermore, this coil 111 is connected to a drive circuit (not shown in the drawings) to enable reversal of the magnetic field at a high frequency. The optical head member 101 and the applied magnetic field member 110 are joined to each other at a portion that does not affect the medium 102 when being driven and allows near-linear scanning on the medium 102 while performing rotational movement. A tapered recess 118 is provided in the joined member and the pivot 109
I would like to give one point of support. The focused beam 117 and the applied magnetic field 112 simultaneously rotate around the pivot 109 and scan the medium. Due to the rotational movement by the pivot 109, mechanical friction is greatly reduced and high efficiency can be achieved during one drive.

FIG. 2 shows a top view of the embodiment showing the scanning configuration. The optical head member and the applied magnetic field member 11 are centered around the pivot 109.
0 scans the medium 102 in a nearly straight line while rotating, and at this time, the shape of the near motor is circular, as shown by the magnet 115 as a typical example. In fact, the length of magnet 115 can be designed to be smaller than the maximum stroke of the focused beam and applied magnetic field.

FIG. 3 is a perspective view showing the optical configuration of the optical head section of this embodiment. The light emitted from the light source 106 passes through the prism 10
The lens 118 has the function of converting the diverging light emitted from the light source, which passes through the lens 7 and enters the lens 118, into parallel light 123.

The parallel light is reflected by the mirror 104, enters the objective lens 103, becomes convergent light, and enters the medium 102. The light that has obtained the information signal from the medium 102 is reflected back to the objective lens and passes through the objective lens 103 → mirror 104 → lens 118 → prism 107
Return to A prism 107 separates the beams, and one beam passes through a wave plate 119 and enters an analyzer 108 . Analyzer 1
At 08, the P polarized light component 124 and the S polarized light component 125 are separated and incident on the light receiving element 120, and the Kerr rotation angle ±θ
Detect K and perform signal detection. The other light enters the light receiving element 121 to detect a tracking error signal, and the other light enters the light receiving element 122 and is guided to an optical system for detecting a focus error signal.

In FIG. 1, the applied magnetic field member 110 is shown having a coil 111 for generating an applied magnetic field at the tip, but in addition to providing the permanent magnet 7 shown in FIG. 5 instead of the coil 111 for generating an applied magnetic field, The optical head unit 101 records information “
It is easy to understand that if the irradiation and non-irradiation of the laser beam 4 is controlled according to the values 0 and 1, it can be applied to an optical modulation method.

〔Effect of the invention〕

As explained above, the following effects can be obtained by the present invention.

1) Since the optical head section 101 and the applied magnetic field section 110 are constructed of the same member, highly accurate position control in the track direction is possible without providing separate drive mechanisms for each.

2) Since tracking control can be performed in the main body of the optical head, the lens actuator can be miniaturized using only a mechanism in the focus direction, which is a nine-lens actuator.

3) Since it is a rotary motion drive with single point support, it is highly efficient drive, and furthermore, it is possible to design a near motor with a length shorter than the maximum scanning stroke, resulting in cost reduction.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention, FIG. 2 is a top view showing the first embodiment of the present invention, and FIG. 3 is a diagram of an optical system used in the optical head section of the present invention. FIG. 4 is a simple explanatory diagram of magnetic field modulation recording, and FIG. 5 is a configuration diagram of a conventional separately driven applied magnetic field means, laser beam, and medium.

Claims (2)

[Claims] (1) Position control in the track direction of an optical head unit that applies a convergent beam emitted from an objective lens to a magneto-optical recording medium and an applied magnetic field unit that applies an applied magnetic field to the magneto-optical recording medium can be performed by the same drive. Featured optical disc device. (2) Claim 1 characterized in that the optical head for irradiating the convergent beam and the applied magnetic field are driven in the same manner, and the optical head is supported around one point and can be driven in the track direction by rotational movement. The optical disc device described in .