JP2985213B2 - Magneto-optical recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording / reproducing apparatus capable of performing recording and / or reproduction on a magneto-optical recording medium.

[Conventional technology]

FIG. 5 shows a magneto-optical recording / reproducing apparatus using a magneto-optical recording medium as an example of an optical recording / reproducing apparatus for recording and / or reproducing on an optical recording medium.

The conventional magneto-optical recording / reproducing apparatus shown in FIG. 5 has an optical system comprising a laser device 58 and an objective lens 59 on the lower surface of the single-sided magneto-optical recording medium 50 when the disc-shaped single-sided magneto-optical recording medium 50 is mounted. In addition, a magnetic field generator 60 as a magnetic system is provided on the upper surface side of the single-sided magneto-optical recording medium 50. Numerical aperture of objective lens 59 (hereinafter referred to as "NA")
Is set to about 0.50 to 0.53.

A drive system (not shown) is provided for driving the optical system in the focus direction and the tracking direction with respect to the single-sided magneto-optical recording medium 50. As for the magnetic system, another drive system (not shown) is provided for driving in the direction indicated by the arrow in FIG. 5 and in the tracking direction.

This magneto-optical recording / reproducing apparatus employs a magnetic field modulation system for recording. In this magnetic field modulation method, it is necessary to perform inversion control of the magnetic field at a high speed, so that a sufficient exciting current cannot be obtained and the intensity of the generated magnetic field is limited. Is disposed near a recording magnetic layer 53 described later. According to the magnetic field modulation method, overwriting (overwriting) is possible.

On the other hand, the single-sided magneto-optical recording medium 50 has a dielectric layer 52 on one side surface of a light-transmitting cover 51 such as polycarbonate.
For example, a recording magnetic layer 53 having a large magneto-optical effect such as a rare earth-transition metal alloy amorphous thin film or the like, a dielectric layer 54, a reflective layer 55, and a protective cover 56 are sequentially laminated. In this case, the thickness t ₁ of the light-transmitting cover 51 is constant, is set to 1.2mm to conventional.

 Next, a simple operation will be described.

First, the single-sided magneto-optical recording medium 50 is placed on a rotating disk (not shown) and driven to rotate, and a magnetic field from the magnetic field generator 60 is applied to the recording magnetic layer 53 in the single-sided magneto-optical recording medium 50. The applied magnetic field is controlled to reverse at a high speed, and the laser beam emitted from the laser device 58 is focused on the recording magnetic layer 53 to which the magnetic field is applied via the objective lens 59 and the translucent cover 51. Thereby, the recording magnetic layer 53 in the region where the laser beam is focused can be magnetized, and the information signal can be overwritten in real time.

By the way, with the increase in the amount of information in recent years, a double-sided magneto-optical recording medium has been developed in which a single magneto-optical recording medium is provided with the above-described recording magnetic layer and the like on both sides and information signals can be recorded on both sides. Have been.

However, in order to perform recording and / or reproduction on such a double-sided magneto-optical recording medium, for example, a magneto-optical pickup constructed integrally with an optical system and a magnetic system as shown in FIG. It is extremely difficult to apply a magnetic field to the two recording magnetic layers via the cover with sufficient strength. In a magnetic field modulation type magnetic field generator, a high-frequency current corresponding to a high-frequency data signal must be passed through an electromagnetic coil.However, the higher the frequency, the more difficult it is for the current to flow through the coil. To
This is because the distance from the magnetic field generator to the recording magnetic layer via the translucent cover is considerably large as described above. Therefore, it is extremely difficult to perform double-sided magneto-optical recording by the magnetic field modulation method with the current technology.

Incidentally, the objective lens 59, the correction of the spherical aberration W _40, which is expressed by the following equation is performed.

W ₄₀ = t / 8 · ((N ² −1) / N ³ ) · NA ⁴ (1) (N: refractive index of light-transmitting cover of optical recording medium; t: light-transmitting cover of optical recording medium) (Thickness) [Problem to be Solved by the Invention] The thickness t of the light-transmitting cover of the optical recording medium has been set to 1.2 mm as described above, but this is conventionally determined. Just need not be technically particularly 1.2mm.

Here, when the thickness t of the translucent cover becomes smaller, for example, in the above-described magneto-optical recording and reproducing apparatus, the distance between the magnetic field generator 60 and the recording magnetic layer 53 (the distance between the recording magnetic layer 53 and the translucent cover 51) is reduced. Distance) is more preferable. That is, a larger magnetic field can be applied to the recording magnetic layer 53 from the translucent cover 51 side.

As described above, the objective lens in the optical system is corrected for spherical aberration. As can be seen from the above equation (1), even if N and NA are constant, the correction value of the objective lens in the optical recording medium can be reduced. It depends on the thickness t of the cover.

If the thickness t of the translucent cover is, for example, 1.2 mm as in the conventional case, the spherical aberration is corrected in the objective lens of the optical system based on this t.

On the other hand, when the thickness t of the light-transmitting cover of another optical recording medium is, for example, 1.2 mm or less for the above-described purpose, recording and / or reproducing of this optical recording medium is performed using a light-transmitting cover of 1.2 mm. It cannot be performed by an optical system having an objective lens in which spherical aberration is corrected based on the thickness t of the conductive cover.

As described above, the thickness of the translucent cover is 1.
The conventional optical recording / reproducing apparatus did not have compatibility between an optical recording medium of 2 mm and an optical recording medium having a thinner transparent cover. Therefore, when using both optical recording media,
It can be very inconvenient.

An object of the present invention is to provide a compatible optical recording / reproducing apparatus capable of performing recording and / or reproduction on any of two types of optical recording media having different thicknesses of a light-transmitting cover. It is.

[Means for solving the problem]

In order to achieve the above object, a magneto-optical recording / reproducing apparatus according to the present invention includes a recording layer to which a laser beam is irradiated for recording and / or reproduction, A first magneto-optical recording medium having a light-transmitting cover through which a beam is transmitted, and having substantially the same external shape, wherein the thickness of the light-transmitting cover is large; and a first magneto-optical recording medium. In a magneto-optical recording / reproducing apparatus which can selectively use a second magneto-optical recording medium having a light-transmitting cover thinner than the light-transmitting cover of the medium, the recording on the first magneto-optical recording medium is performed. And / or an optical system having an objective lens configured to converge the laser beam on the recording layer via the translucent cover when performing reproduction, and the first or second magneto-optical recording Medium And a magnetic head for applying a magnetic field to the recording layer when performing recording and / or reproduction, and compensating for aberrations in the objective lens when performing recording and / or reproduction on the second magneto-optical recording medium. Therefore, between the objective lens and the second magneto-optical recording medium,
A light-transmitting compensator added so as to face the second magneto-optical recording medium together with the magnetic head.

[Action]

The objective lens in the optical system is configured such that recording and / or reproduction with respect to the first magneto-optical recording medium having a thicker light-transmitting cover can be performed.

When performing recording and / or reproduction on the second magneto-optical recording medium having a thinner light-transmitting cover with the objective lens, a light-transmitting compensator having a predetermined thickness is connected to the objective lens. When applied between the second magneto-optical recording medium and the second magneto-optical recording medium, the thickness of the thinner light-transmitting cover in the second magneto-optical recording medium apparently increases. Aberrations caused by the thinner cover can be compensated. Therefore,
The optical system enables recording and / or reproduction on both the first and second magneto-optical recording media.

〔Example〕

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS. 1 to 4B.

1 and 2 are sectional views showing a schematic configuration of the magneto-optical recording / reproducing apparatus of the present embodiment.

FIG. 1 shows a case where recording and reproduction are performed on a double-sided magneto-optical recording medium 43 (hereinafter, referred to as a “double-sided medium”) in the magneto-optical recording and reproducing apparatus of the present embodiment. FIG. 2 shows a case where recording and reproduction are performed on the single-sided magneto-optical recording medium 50 (hereinafter, referred to as “single-sided medium”) shown in FIG. 5 in the same magneto-optical recording and reproducing apparatus as FIG. .

The magneto-optical recording / reproducing apparatus shown in FIG. 1 includes a first optical system 1, a first drive system (not shown) for driving the first optical system 1, and a magnetic head constituting the first magnetic system. 29,
A first optical glass plate 28 for forming the magnetic head 29 and performing aberration compensation, a second optical system 21, and a second drive (not shown) for driving the second optical system 21 System, a magnetic head 19 constituting a second magnetic system, a second optical glass plate 18 on which the magnetic head 19 is formed, and a spindle motor 37 for rotating a magneto-optical recording medium having a rotating shaft 37a. Each has.

As described above, in the magneto-optical recording / reproducing apparatus of the present embodiment,
Two magneto-optical pickup devices including an optical system, a magnetic system, and a drive system are respectively provided above and below in FIGS. 1 and 2 via a magneto-optical recording medium.

The magneto-optical recording / reproducing apparatus according to the present embodiment is configured so that overwriting (overwriting) can be performed by a magnetic field modulation method.

The first optical system 1 includes a first objective lens 2, a polarizing beam splitter 3, a collimator lens 4, a cylindrical lens 5, a laser diode 11, and a photodetector 12 for focusing a laser beam.

The first optical system 1 has a thickness t ₁ as shown in FIG.
The above-described single-sided medium 50 having the translucent cover 51 set to 1.2 mm is configured to be able to cope with recording and reproduction.

In the first objective lens 2, the spherical aberration that is determined as t = 1.2 mm in the above equation (1) is corrected. Note that, in the value of t, the thickness of the dielectric layer 52 of the single-sided medium 50 is considerably smaller than 1.2 mm, and thus need not be considered.

The second optical system 21 is disposed so as to face the first objective lens 2 and has a second objective lens 22 for converging a laser beam, a polarization beam splitter 23, a collimator lens 24, a cylindrical lens 25. , A laser diode 31 and a photodetector 32.

The double-sided medium 43 shown in FIG. 1 is one proposed by one of the inventors of the present application together with another in the specification and drawings of Japanese Patent Application No. 1-274734, and has a common base material 44.
A high magnetic permeability layer 45, a photo-curable resin layer 46, a magneto-optical recording layer 47, an adhesive layer 48, and a light-transmitting protective plate 49 are sequentially laminated on both surfaces of the substrate.

Protective plates on one surface (upper surface in FIG. 1) A and the other surface (same lower surface) B of the double-sided medium 43
Configure the translucent cover which transmits the laser beam with both having a light-transmitting property with 49 and the adhesive layer 48, the sum t ₂ of their thickness, respectively on the upper surface A side and the lower surface B side 1.2mm or less , For example, 0.5 mm.

The high magnetic permeability layer 45 is, for example, a transition metal such as Fe, Co, and Ni,
And a material having a high magnetic permeability such as permalloy, sendust, or an amorphous magnetic alloy, which is an alloy thereof, so that the perpendicular magnetic field efficiency of the double-sided medium 43 in the perpendicular direction can be increased.

The second optical system 21 is provided for the double-sided medium 43 described above.
It is configured to be able to cope with the recording and reproduction.

In the second objective lens 22, the NA is set to be the same as the NA of the first objective lens 2, and the spherical aberration is calculated by, for example, t = 0.5 mm in the above equation (1). ing. In correcting the spherical aberration, the thickness of the second optical glass plate 18 can be considered as necessary, as described later.

As described above, in the first objective lens 2 and the second objective lens 22, since t in the above equation (1) is different from each other, the correction values of the spherical aberration are different from each other. Therefore, the double-sided magneto-optical recording medium 43 is provided by the first objective lens 2.
When performing recording and reproduction on the lower surface B side of the first objective lens 2, spherical aberration occurs without being corrected in the first objective lens 2, and therefore compensation for this spherical aberration must be performed.

For the above-mentioned compensation, the first optical glass plate 28 is
43, between the lower surface B of the first objective lens 2 and the lower surface B. The first optical glass 28 can be made of a light-transmitting material such as quartz, but is not limited to this, and may be any material having a light-transmitting property.

When the first optical glass plate 28 is added as described above, the thickness t ₃ of the first optical glass plate 28 is equal to the thickness of the adhesive layer 48 and the protective plate 49 of the double-sided medium 43. Kazu Sano t ₂ is determined to be substantially equal to the thickness t ₁ of the light-transmitting cover 51 of the single-sided media 50. That is, it is determined that t ₂ + t ₃ = t ₁ substantially holds. By adding a first optical glass plate 28 having a plate thickness t ₃ , t ₂ is increased apparently by t ₃
Since it is substantially equal to t ₁ , the spherical aberration in the first objective lens 2 is appropriately corrected as in the case of the single-sided medium 50.

The second optical glass plate 18 in the second optical system 21 is disposed between the upper surface A of the double-sided medium 43 and the second objective lens 22 so as to be in contact with the second objective lens 22, and
The first optical glass 28 may be made of a material having a light-transmitting property, such as quartz.

The thickness of the second optical glass plate 18 is smaller than that of the first optical glass plate 28. Further, if necessary, the spherical aberration can be corrected in advance in the second objective lens 22 by the above-mentioned equation (1) in consideration of the thickness of the second optical glass plate 18. Further, the second optical glass plate 18 may be provided with a hole through which a laser beam passes in order to prevent reflection. In this case, the thickness of the second optical glass plate 18 is set to the second objective lens.
It is not necessary to consider the correction of the spherical aberration of 22.

As shown in FIG. 3, on the surface 18a of the second optical glass plate 18, a conductor 17a for flowing a current of a high-frequency signal to generate a magnetic field is formed in a spiral shape to form a magnetic head 19. It is formed as a coil pattern 17. Back side of the optical glass 18 on which the coil pattern 17 is not formed
In 18b, the optical glass 18 and the second objective lens 22 are bonded and fixed such that the center of the coil pattern 17 is aligned with the center of the second objective lens 22.

On the surface 28a of the first optical glass plate 28, similarly to the second optical glass plate 18, a conductor 27a is formed as a spiral coil pattern 27 to constitute the magnetic head 29. On the back surface 28b of the optical glass plate 28, the first optical glass plate 28 and the first optical glass plate 28 are aligned so that the center of the coil pattern 27 and the center of the first objective lens 2 coincide.
Is fixed so as to be in contact with the objective lens 2. The first optical glass plate 28 is removed during recording and reproduction on the single-sided medium 50.

The optical glass plates 18 and 28 have surfaces 18a and 28a on which the coil patterns 17 and 27 are formed, respectively.
43 can be arranged so as to approach the upper surface A and the lower surface B, respectively.

As described above, the first optical glass plate 28 is used both for compensation of aberration and for providing the coil pattern 27 for the magnetic head 29.

 Next, the operation will be described.

First, the case of recording on the double-sided medium 43 will be described.

As shown in FIG. 1, the upper surface A of the double-sided medium 43 is
Is mounted on a rotating disk (not shown) so that the lower surface B faces the first optical system 1 on the optical system 21 side, and is rotated by a spindle motor 37. The upper surface (one surface) A and the lower surface (the other surface) B of the double-sided medium 43 may be upside down in FIG.

At the same time, the first optical system 1 is driven by the first drive system (not shown) together with the first optical glass plate 28 by an arrow F in FIG.
Is driven and displaced in the focus direction, which is the optical axis direction of the first objective lens 2 indicated by. Further, it is driven and displaced in a tracking direction which is a direction perpendicular to the optical axis of the objective lens 2 indicated by an arrow T in FIG. Further, the second optical system 21 is driven together with the second optical glass plate 18 by a second drive system (not shown) in the F direction and the T direction in synchronization with the drive of the first optical system 1 respectively. Displaced.

At the same time, by supplying a high-frequency current signal obtained by amplifying a signal to be recorded to the coil pattern 27 of the magnetic head 29 provided on the first optical glass plate 28 on the lower surface B side of the double-sided medium 43, A magnetic field is generated. This magnetic field is subjected to high-speed reversal control according to the recording signal, and is applied to the magneto-optical recording layer 47 on the lower surface B side of the double-sided medium 43. Then, in the area of the magneto-optical recording layer 47 where the magnetic field is applied,
The laser beam emitted from the laser diode 11 passes through the collimator lens 4, the polarizing beam splitter 3, the first objective lens 2, and the first optical glass plate 28, and further adheres to the translucent protective plate 49 of the double-sided medium 43. The light is focused through the agent layer 48. The information signal can be recorded by raising the temperature of the magneto-optical recording layer 47 to the Curie point or higher.

Also, a magnetic field generated by supplying a current signal to the coil pattern 17 of the magnetic head 19 provided on the second optical glass plate 18 on the upper surface A side of the double-sided medium 43 in the same manner as described above, The voltage is applied to the magneto-optical recording layer 47 on the upper surface A side of the double-sided medium 43. Then, similarly to the lower surface B, the laser beam from the laser diode 31 is transmitted through the collimator lens 24, the polarizing beam splitter 23, the second objective laser beam 22, the second optical glass plate 28, and the double-sided medium 43. The recording is performed by focusing on the magneto-optical recording layer 47 to which the above-described magnetic field is applied via the conductive protective plate 49 and the adhesive layer 48, respectively.

When reproducing the information signal recorded on the lower surface B of the double-sided medium 43, the laser beam is
Irradiation with lower output intensity than during recording from the magneto-optical recording layer
Focused on 47. Then, the light reflected from the magneto-optical recording layer 47 follows a path reverse to that of the incident light, changes its direction by the polarizing beam splitter 3, and is guided to the photodetector 12 via the cylindrical lens 5. Although the intensity of this light changes due to the magneto-optical effect in the magneto-optical recording layer 47,
By reading the change in the photodetector 12, reproduction is performed.

The reproduction on the upper surface A of the double-sided medium 43 is performed in the same manner as in the case of the lower surface B.

As described above, by using the first objective lens 2 for recording and reproducing with respect to the conventional single-sided medium 50 having the thicker (eg, 1.2 mm) light-transmitting cover 51, the thickness of the laser beam transmitting thickness is reduced. Recording and reproduction on the lower surface B side of the double-sided medium 43 having a thinner translucent cover (protective plate 49 and adhesive layer 48) can be performed by adding the first optical glass plate 28 as described above. . Therefore, double-sided media
Recording and reproduction can be performed on both sides A and B of 43.

Further, the first objective lens 2 and the first optical glass plate 28 are placed on the lower surface B side of the double-sided medium 43, and the second objective lens 22 and the second
The optical glass plate 18 is disposed on the upper surface A side of the double-sided medium 43, respectively, and the coil patterns 27, 17 provided on the first and second optical glass plates 28, 18 respectively correspond to the lower surface B of the double-sided medium 43. And the upper surface A, respectively. The thickness t ₂ of the translucent cover made of the adhesive layer 48 protective plate 49. which the transmitted laser beam is smaller than. Therefore, the magnetic head
Since the distance between each of the coil patterns 27 and 17 constituting the coils 29 and 19 and the magneto-optical recording layer 47 of the double-sided medium 43 can be extremely short, the double-sided light by the magneto-optical modulation method, which has been considered extremely difficult until now, Recording on a magnetic recording medium becomes possible.

In addition, the magnetic heads 29 and 19 have first and second magnetic heads, respectively.
Are fixed to the objective lenses 2 and 22, and are interlocked with the focus servo in the T direction of these objective lenses 2 and 22, so that a drive system for the magnetic system can be omitted, and
The magnetic field applied to the magneto-optical recording layer 47 can be kept constant.

When performing recording on the double-sided medium 43 as described above, since the double-sided medium 43 includes the high magnetic permeability layer 45, the magnetic flux from the magnetic heads 19 and 29 is, for example, as indicated by a broken line in FIG. Next, a magnetic closed loop is formed. Therefore, it is preferable that the magnetic flux applied to the magneto-optical recording layer 47 of the double-sided medium 43 during recording can be effectively converged and the vertical magnetic field efficiency can be increased.

Further, according to the above embodiment, it is possible to perform various recording and reproduction on the double-sided magneto-optical recording medium. For example, the first and second optical systems 1 and 21 and the magnetic heads 29 and 19
Can be simultaneously recorded on the upper surface A and the lower surface B of the double-sided medium 43. Simultaneous reproduction can be performed by using the first and second optical systems 1 and 21 at the same time. This allows for higher capacity,
Higher speed recording and reproduction of information signals can be performed.

Further, it is possible to perform recording or reproduction on one side of the double-sided medium 43 first, and then perform recording or reproduction on the other side. As a result, recording and reproduction with twice the capacity of a single-sided magneto-optical recording medium can be performed.

Next, a case where recording and reproduction are performed on the single-sided medium 50 will be described.

As shown in FIG. 2, the single-sided medium 50 is so described that the light-transmitting cover 51 side faces the first optical system 1 side and the protective cover 56 side faces the second optical system 22 side. Double-sided media 43
It is mounted and rotated in the same way as.

In this case, the first optical glass plate 28 is removed from between the first objective lens 2 and the translucent cover 51. The laser beam is converged on the recording magnetic layer 53 by the first optical system 1, and the magnetic field of the single-sided medium 50 is changed by the magnetic head 19 provided on the second optical glass 18 on the second optical system 22 side. It is applied to the recording magnetic layer 53 from the protective cover 56 side. Then, the first optical system and the second optical system are driven and displaced in synchronization with the T direction and the F direction. The above is different from the case of the double-sided medium 43, and the recording is performed in the same manner in the other cases.

The reproduction of the single-sided medium 50 can be performed by the first optical system 1 in the same manner as in the case of the double-sided medium 43 (however, the first optical glass plate 28 has been removed).

In the first objective lens 2 and the second objective lens 22 described above, their NAs can both be set to be larger than the conventional 0.50 to 0.53, for example, about 0.60, thereby narrowing the laser beam. Therefore, the recording can be performed at a higher density than before, and the capacity can be increased. In this case, reproduction of the conventional optical recording medium recorded by the conventional NA objective lens can be performed by the larger NA objective lens as described above.

Next, when the double-sided medium 43 or the single-sided medium 50 is mounted on the magneto-optical recording / reproducing apparatus shown in FIG. 1 and FIG. 2, the first optical glass plate 28 is detected by detecting which medium it is. 1
A specific example of an automatic mechanism for automatically feeding and adding or removing between the objective lens 2 and the recording medium will be described with reference to FIGS. 4A and 4B.

The automatic mechanism shown in FIG. 4A is provided with a first objective lens 2 and an actuator unit 71 of the objective lens 2, and is driven along a pair of guide shafts 73a and 73b. One optical glass plate 28 and a motor 78 for rotating a pair of rotary arms 75a and 75b via a rotary shaft 74 are provided. And, for example, the double-sided medium
43 is stored in the disk cartridge 62. The disc cartridge 62 has a long window hole 63 at a corner thereof, and a portion occupying about half of the long window hole 63 is closed by a closing piece 64.

The automatic mechanism has a light emitting element at a position corresponding to the long window hole 63 of the disc cartridge 62 when the light emitting element is mounted at a predetermined position.
There is provided a medium detecting means comprising a light receiving element 65 and a pair of light receiving elements 66a, 66b.

 The operation of the above automatic mechanism will be described.

When the disc cartridge 62 containing the double-sided medium 43 is mounted at a predetermined position, light from the light emitting element 65 is incident on the light emitting element 66b as shown in FIG. 4B, and a predetermined signal is omitted from the drive head 70. Is sent to the driving mechanism. At this time, the light from the light emitting element 65 does not enter the light receiving element 66a due to the obstruction of the closing piece 64. In addition, the first optical glass plate 28
First holes 76a and 76b provided in the rotating arms 75a and 75b
Pins 77a, 7 provided on both sides of the optical glass plate 28
7b are in the fitted state and in the raised position shown by the solid line in FIG. 4B (in FIG. 4A, the pins 77a and 77b and the holes 76a and 76b are not fitted respectively for convenience. As shown).

Next, the drive head 70 is moved along the guide shafts 73a and 73b in the direction of arrow L in FIG. 4B to the position indicated by the dashed line in FIG. .

Subsequently, the first optical glass plate 28 is lowered from the above-mentioned raised position while rotating with the rotating arms 74a and 75b around the rotating shaft 74 by the motor 78 in the direction of arrow M in FIG. 4B.

Then, at the position shown by the one-dot chain line in FIG. 4B, the first
The optical glass plate 28 has a pair of holes 79a, 79b provided in the optical glass plate 28 fitted to a pair of positioning pins 72a, 72b provided in the drive head 70,
It is positioned and placed on the upper surface 70a of the drive head 70.
Thus, the center of the coil pattern 27 formed on the first optical glass plate 28 and the center of the first objective lens 2 are aligned, and the drive head 70 and the first optical glass plate 28 Become one.

Next, the rotating arms 75a and 75b are moved by a predetermined amount in the N 'direction and the N direction shown in FIG. 4A by driving means (not shown), and the holes 76a and 76b and the pins 77a and 77b are moved.
Are released from each other.

Next, the first optical glass plate 28 positioned and mounted on the drive head 70 as described above and released from the rotary arms 75a and 75b is moved together with the drive head 70 in the direction of the arrow L 'in FIG. 4B. 4B of FIG. 4B by a drive mechanism not shown.
It moves to a predetermined position for recording or reproduction indicated by a chain line.

As described above, the magneto-optical recording / reproducing apparatus of this embodiment can be automatically arranged in the arrangement shown in FIG.

When a disk cartridge containing the above-described single-sided medium 50 is mounted on the magneto-optical recording / reproducing apparatus, the position of the closing piece 64 as shown in FIG. Is incident on the light receiving element 66a (shown by a broken line in FIG. 4B), and when this light is incident on the light receiving element 66a, a predetermined signal is sent to a drive mechanism not shown. Then, the first optical glass plate 28
Can be removed from the drive head 70 by the above-mentioned automatic mechanism in an operation reverse to the above-described operation. Therefore, the arrangement shown in FIG. 2 can be automatically performed.

As described above, the magneto-optical recording / reproducing apparatus of the present embodiment includes the single-sided medium 50 having the conventional light-transmitting cover 51 (for example, 1.2 mm) and the thinner light-transmitting cover, respectively. It has compatibility with the double-sided medium 43 included therein, and can record and reproduce data regardless of which medium is loaded.

It is needless to say that the double-sided medium 43 may be a medium having a structure similar to that shown in FIG.

Although the present embodiment uses a magneto-optical recording medium, the present invention is not limited to this, and any recording medium (for example, a read-only optical recording medium or a write-once type It is clear that the recording medium may include an optical recording medium.

〔The invention's effect〕

According to the magneto-optical recording medium device of the present invention, an optical recording medium having a thin translucent cover to increase the information recording capacity, and a thin translucent cover to increase the information recording capacity; It is possible to use a new recording medium such as a magneto-optical recording medium that irradiates a recording surface with a laser beam and applies a magnetic field to the recording surface so that information can be quickly rewritten and read. It is possible to use an optical recording medium or a magneto-optical recording medium having a thick light-transmitting cover, which is extremely convenient in use.

[Brief description of the drawings]

1 to 4B show an embodiment of a magneto-optical recording / reproducing apparatus according to the present invention. FIG. 1 is a cross-sectional view of a magneto-optical recording / reproducing apparatus using a double-sided magneto-optical recording medium as a recording medium.
FIG. 2 is a cross-sectional view when a conventional single-sided magneto-optical recording medium is used in the magneto-optical recording / reproducing apparatus shown in FIG. 1, and FIG. 3 is for forming a magnetic head in the magneto-optical recording / reproducing apparatus shown in FIG. FIG. 4A is a plan view showing an example of a coil pattern formed on an optical glass plate. FIG. 4A shows an optical glass plate for aberration compensation in FIGS. 1 and 2 between an objective lens and a magneto-optical recording medium. FIG. 4B is a perspective view showing a specific example of an automatic mechanism for automatically adding or removing, and FIG. 4B is a side view of the automatic mechanism shown in FIG. 4A. FIG. 5 is a schematic sectional view of a conventional magneto-optical recording / reproducing apparatus. In the reference numerals used in the drawings, 1... A first optical system (optical system) 2... A first objective lens (objective lens) 28... A first optical glass plate (a translucent compensating plate) 43. ... double-sided magneto-optical recording medium (second optical recording medium) 47 ... magneto-optical recording layer (recording layer) 48, 49 ... adhesive layer, translucent protective plate (translucent cover) 50 ... single-sided light Magnetic recording medium (first optical recording medium) 51 translucent cover 53 recording magnetic layer (recording layer) t ₁ thickness of translucent cover 51 t ₂ adhesive layer 48 and transparent layer The sum of the thickness of the first optical glass plate 28 and the thickness t ₃ of the optical protection plate 49...

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Claims (1)

(57) [Claims] A recording layer irradiated with a laser beam for recording and / or reproduction; and a light-transmitting cover provided so as to cover the recording layer and transmitting the laser beam. Of the first magneto-optical recording medium, the thickness of the light-transmitting cover being thicker, and the light-transmitting cover of the first magneto-optical recording medium thinner than the light-transmitting cover. In a magneto-optical recording / reproducing apparatus which can selectively use a second magneto-optical recording medium provided with a cover, when performing recording and / or reproducing on the first magneto-optical recording medium, An optical system having an objective lens configured to converge on the recording layer via a light-transmitting cover; and an optical system for recording and / or reproducing the first or second magneto-optical recording medium. Record A magnetic head for applying a magnetic field to the objective lens, and the objective lens and the second magneto-optical recording medium for compensating aberrations in the objective lens when performing recording and / or reproduction on the second magneto-optical recording medium A magneto-optical recording / reproducing apparatus, comprising: a light-transmitting compensating plate which is provided so as to face the second magneto-optical recording medium together with the magnetic head.