JPS59215044A - Recording medium of recording and reproducing device - Google Patents

Abstract

PURPOSE:To record a large quantity of data with a simple constitution by adopting the two-layer structure where the 1st and 2nd recording medium layers are arranged oppositely via a gap. CONSTITUTION:The 1st and 2nd bases 4, 7 in which recording medium layers 3, 6 and filters 2, 5 are formed and made of a synthetic resin plate or a glass plate excellent in the transmittivity of light are laminated via a spacer 8 so as to form an optomagnetic disc 1. The 1st and 2nd recording medium layers 3, 6 are formed by thin films having different Curie points from each other such as GdTbFe or TdDyFe amorphous magnetic thin film or the like. The 1st filter 2 has a high reflectance to a laser beam 10 irradiated to the 1st recording medium layer 3 and a high transmittivity to a laser beam 11 irradiated to the 2nd recording medium layer 6 and the 2nd filter 5 is made of silicon dioxide or the like having a high reflectance to the beam 11 and a high transmittivity to the beam 10.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a recording medium for a recording/reproducing apparatus in which data is recorded and reproduced by irradiating the recording medium with a laser beam.

PRIOR ART Conventionally, in the recording medium of a recording/reproducing apparatus that records and reproduces data by irradiating a recording medium such as an optical disk or a magneto-optical disk with a laser beam, the recording medium layer of the recording medium is made of a thin layer. Therefore, there was a problem that large amounts of data could not be recorded. In addition, the above disadvantages can be solved by increasing the data recording density, but the track on which data is recorded must be tracked with high positional accuracy, which has the disadvantage of complicating the laser beam tracking mechanism. .

OBJECTS OF THE INVENTION An object of the present invention is to provide a recording medium for a recording/reproducing apparatus capable of recording a large amount of data with a simple configuration, in view of the conventional drawbacks mentioned above.

Composition of the invention The present invention will be described below according to one embodiment.

FIG. 1 is an enlarged 1fl sectional view showing the +S structure of the recording medium of the recording/reproducing apparatus according to the present invention. 1 In the figure, a magneto-optical disk 1 as a recording medium has a first recording medium layer 3 formed on the -plane by a film forming technique such as a high-frequency sputter link method, a vacuum evaporation method, a photoetching method, or a laser processing method. Both include a first substrate 4 made of a synthetic resin plate or a glass plate with excellent light transmittance, on which a first filter 2 is formed on the F layer, and a second substrate 4 with a second filter 5 on the negative side. The second recording medium layer 6 of the second substrate 7 is made of a synthetic resin plate or a glass plate with excellent light transmittance and is formed by the film forming technique described above. 3 and the second recording medium layer 6 are opposed to each other, and a spacer 8 is interposed between the first substrate 4 and the second substrate 7 to provide a gap 9 having a predetermined width q. are laminated. nil entry first row and second row
The recording medium layers 3 and 6 are made of G d T b Fe amorphous magnetic thin film 11 whose temperature at one point is approximately 165°C.
! (Gd Nigathrinium, Tb.Terbium), or a TbDyFe amorphous magnetic thin film (Dy: Dysprosium) whose single point has a temperature of approximately 75° C., and is formed by magnetic thin films having different single points from each other. The first filter 2 is on the first recording medium layer 3! 1.
It has a high reflectance for the wavelength λ2 of the laser beam 1o irradiated onto the second recording medium layer 6, and a high transmittance for the wavelength λ2 of the laser beam 11 irradiated onto the second recording medium layer 6. The second filter 5 is made of silicon dioxide (S102) or oxidized silicon dioxide (S102) whose film thickness is determined so that it has a high reflectance for the laser beam 11 described in IXI and a high transmittance for the laser beam 1o described in 1111. Made of silicon (SiO), etc. The n11 gap 9 is set to a predetermined width Q that can regulate heat conduction to the other recording medium layer when one recording medium layer is irradiated with the laser beams 1o and 11.

Figure 2 is an explanatory diagram showing the optical system of recording/reproduction-1AfFi.
FIG. 3 is an explanatory diagram showing the data recording state, and FIG. 4 is an explanatory diagram showing the data reading state.

First, the case of recording data on the first recording medium layer 3 will be described.

A laser beam 1o irradiated from a first semiconductor laser element 12 whose output is controlled to the temperature of the first recording medium layer 3 and turned ON and OFF based on recorded data. is made into a parallel beam by the objective lens 20, and then the polarizing beam splitter 22 is selectively moved to the optical axis by the optical path switching mirror 21 rotated to the position shown by the broken line in FIG. Board 2
3, and the optical path is changed via the optical path switching mirror 24, which has been rotated to the position shown by the broken line in FIG. The laser beam 10 whose optical path has been changed is focused by the objective lens 25 on the first recording medium layer 3 as shown in FIG. Data is recorded by heating and orienting the magnetization C at the irradiated area in the direction of the upward magnetic field M. That is, among the two bell signals, for example, the signal "1" is caused by the magnetization C oriented in the direction of the magnetic field M when the first semiconductor laser element 12 is turned on, and the signal "0°" is caused by the magnetization C oriented in the direction of the magnetic field M when the first semiconductor laser element 12 is turned on. When the laser element 7 is turned off, the magnetization C oriented in the opposite direction to the magnetic field M is used for recording.The first recording medium layer 3
When the laser beam 1o is applied to the 24-th recording medium layer 6, heat conduction is blocked by the gap 9, and the temperature rise is regulated. Further, since the laser beam 1o irradiated onto the first recording medium layer 3 has a wavelength λ1 and is reflected by the first filter 2 having a high reflectance, the irradiation onto the second recording medium layer 6 is is regulated. And the laser beam 8 reflected by the first filter 2
The phase is shifted by 90° by passing through the λ1/4 plate 23 in the same way as in the operation described in 1, and the optical path is changed to the direction of the cylindrical lens 26 by the polarizing beam splitter 22.
A four-part photodiode 27 is connected through the cylindrical lens 26.
is irradiated. Through this operation, the objective lens 25 divides the four-part photodiode 27 in accordance with the amount of incident reflected light.
The laser beam 1o is moved horizontally in the downward direction and in the horizontal direction by the Taos 28, which is driven based on the differential output horns (not shown) of each cell outputted from the laser beam 1o. Control the focus so that the focus is on the top.

On the other hand, in order to record data on the recording medium layer 6 of ff12, it is necessary to raise the temperature of the second recording medium layer 6 to one point or higher.
The laser beam 11 irradiated from the second semiconductor laser element 13 which is controlled ON and OFF based on the recorded data is converted into the mI laser beam 10 by an optical path switching mirror 29 (indicated by a broken line in the figure). After being positioned on the same optical axis, the second recording medium layer 6 is focused in the same manner as in the above operation, and the boride C at the irradiated area is oriented in the direction of the magnetic field M to record data. Note that the laser beam 11 is selectively moved onto the optical axis by the input 2/4 plate 3.
polarized by 0. Furthermore, since the first filter 2 has a high transmittance for the wavelength λ2, the laser beam 11 is allowed to be irradiated onto the second recording medium layer 6. After the laser beam 11 is reflected by the second filter 5 which has a high reflectance for the input wavelength 2, it passes through the optical path switching mirror 24, the λ2/4 plate 30, the polarizing beam splitter 22, and the like in the 0M operation. The light enters a four-part photodiode 27 via a cylindrical lens 26.

Next, the operation of reading data recorded on the first recording medium layer 3 in 11j1 will be explained.

The laser beam IO irradiated from the first semiconductor laser element 12 whose output is controlled to a temperature below one Curie point of the first recording medium layer 3 has its optical path changed by a fixed mirror 40, and then passes through a grating 41, a polarizer 42, The beams are then formed into three parallel beams by the objective lens 43. Among these parallel beams, the central beam is used for reading data and controlling the focus of the objective lens 25, and the beams at both ends are used for tracking control. and laser beam 10
The optical path is changed by the fixed mirror 44, the half mirror 45, and the optical path switching mirror 24 which is rotated as shown by the solid line in FIG. , is reflected by the first filter 2 which has a high reflectance for the wavelength λl. As shown in FIG. 4, the plane of polarization of the reflected light is rotated by +θ or -θ in accordance with the orientation direction of magnetization C at the irradiation location.

That is, if the plane of polarization of the reflected light is rotated by +θ due to the magnetization C oriented in the direction of the arrow in the figure, the plane of polarization is rotated 7-10 by the magnetization C oriented in the opposite direction to the arrow. The reflected light from the first recording medium layer 3 passes through the optical path switching mirror 24 and the half mirror 45.
When the light enters the first and second analyzers 47 and 48 through
The second analyzer 48 detects the reflected light whose polarization plane has been rotated by one theta. and mI
Four-divided photodiodes 50 and 53 correspond to the amount of reflected light incident from the first and second analyzers 47 and 48.
The data recorded on the first recording medium layer 3 is read by the differential output output from the first recording medium layer 3. The laser beam 10 irradiated onto the first recording medium layer 3 is directed in the vertical and horizontal directions based on the differential output output from each cell of the quadrant photodiode 53 in accordance with the amount of reflected light. The focus is controlled by the objective lens 25 that moves to . Further, the photodiodes 49a-49b152a and 52b detect the light intensity of both end beams in the reflected light incident from the first and second analyzers 47 and 48, and track the laser beams 8 and 10 by their differential outputs. - King control.

First, the operation of reading data recorded on the second recording medium layer 6 will be explained.

When the second recording medium layer 6 is irradiated with a laser beam 11 from the second semiconductor laser element 13 whose horn is controlled to a temperature below one Curie point, the laser beam 11 follows the same optical path as in the reading operation described above. Then, the second recording medium layer 6 is focused. At this time, since the first filter 2 has a high transmittance for the wavelength λ2 of the laser beam 11, the second recording medium layer 6 is allowed to be irradiated with the laser beam 11. The laser beam 11 is then reflected by the second filter 5 which has a high reflectance for the wavelength λ2, and the plane of polarization is rotated to +θ or -0 in accordance with the orientation direction of the magnetization C at the irradiation location. After, 1
111, the first and second analyzers 47.
48 respectively.

Then, similarly to the operation described in (1), after the first and second analyzers 47 and 48 detect the respective reflected lights whose polarization planes have been rotated to +θ or -θ, the respective four-part photodiodes 50 - Read the data recorded on the second recording medium layer 6 by the differential output from 53;

Therefore, in this embodiment, a large amount of data is recorded and reproduced by selectively irradiating the first and second recording medium layers 3 and 6, which are arranged facing each other and formed in two layers, with a laser beam IO. At the same time, for example, the laser beam 10 is applied to the first recording medium layer 3 at jl! 11, the gap 9 restricts heat conduction to the second recording medium layer 6, making it possible to prevent data recorded on the second recording medium layer 6 from being erroneously erased.

In this embodiment, the magneto-optical disk 1 has a two-layer structure in which the first and second recording medium layers 3 and 4 are arranged facing each other with a gap 9 in between. At least two or more substrates on which recording medium layers A1 to ATL, each having a different Curi point, are formed on the respective recording medium layers A1 to ATL.
T+ are opposed to each other, and mutual recording medium layers A1 to An
It is also possible to implement the multilayer recording medium 1 in which a gap C1=Cn-1 having a predetermined width is provided with spacers B1 to Bn-1 interposed therebetween.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the present invention provides an apparatus for recording and reproducing data by irradiating a laser beam onto a recording medium while rotating the recording medium.
A first substrate on which a recording medium layer is formed, and a second substrate on which a second recording medium layer is formed on one surface facing the first recording medium layer. A large amount of data can be recorded using a simple configuration in which a spacer is interposed between the first recording medium layer and the second recording medium layer to a predetermined distance of 6. It is a recording medium for a recording/reproducing device that uses a computer.

[Brief explanation of the drawing]

Fig. 1 is a 1//W enlarged sectional view showing the structure of a recording medium of a recording/reproducing apparatus according to the present invention, Fig. 2 is an explanatory diagram showing an optical system of the recording/reproducing apparatus, and Fig. 3 shows the state of data recording. FIG. 4 is an explanatory diagram showing a data reading state, and FIG. 5 is a modified embodiment of the present invention. -11- In the figure, 1 is a magneto-optical disk as a recording medium, 3 is a first recording medium layer, 4 is a first substrate, 6 is a second recording medium layer,
7 is a second substrate, 8 is a spacer, 9 is a gap, 10 and 11
is a laser beam. ! l + Kn people Brother Industries, Ltd. agent Patent attorney Ken Ito − = 12−

Claims (1)

[Claims] 1. In an apparatus for recording and reproducing data by irradiating a laser beam onto a recording medium while rotating the recording medium, a first recording medium layer is formed on at least one surface. and a second substrate having a second recording medium layer formed on one surface facing the first recording medium layer, and between the first substrate and the second substrate. 1. A recording medium for a recording/reproducing apparatus, characterized in that a spacer is interposed between the first recording medium layer and the second recording medium layer so that the gap between the first recording medium layer and the second recording medium layer is set to a predetermined value.