JPH04335237A - Device for magneto-optical disk - Google Patents

Abstract

PURPOSE:To simultaneously record/reproduce data of both faces by means of one magnetic head and to realize a low cost and mimituarization by switching the polarity of a reproducing signal or a recording signal concerning the A/B faces. CONSTITUTION:An A/B faces discriminating means 18 discriminates the A/B faces of an optical disk 11a from the detection hole of a cartridge 11, etc. The signal read from an A head part 12A and the B head part 12B is binarized in first and second reproducing signal detecting circuits 13A and 13B and transmitted to first and second polarity inverse circuits 14A and 14B at the time of reproducing. The signals are alternately inverted and the output signal is inputted to a demodulating circuit 15 by the output of the discriminating means 18. Therefore, the polarity of the reproducing signal viewed from the demodulating circuit 15 becomes same even when reproduction is simultaneously operated to the both faces of the both face disk 11a so that the reproduction of the both faces can be simultaneously operated and the low cost is realized. Recording is executed in a same way.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] This invention relates to a magneto-optical disk equipped with a medium having information parts that can be recorded and reproduced on both the front and back sides.
It relates to a magneto-optical disk device that records and plays information using a unique head for each side, and in particular, it is capable of simultaneously recording and reproducing operations on both sides of a magneto-optical disk using one (one side) head. The present invention relates to a magneto-optical disk device that enables high-speed recording and reproduction of information.

0002

2. Description of the Related Art Conventionally, a magneto-optical disk device having an information section that can be recorded and reproduced on both the front and back sides has been known. Also,
Overwritable magneto-optical disk devices using dual-layer media have also been known (for example, JP-A-2-12
1103). Before describing these magneto-optical disk devices having information sections that can be recorded and reproduced on both the front and back surfaces, a magnetic head in a conventional magneto-optical disk device will be explained.

FIG. 9 is a block diagram showing an example of the main parts near the head of a conventional magneto-optical disk device, and a diagram showing the relationship between the signal waveforms.
(2) shows the state at the time of reproduction, and (2) shows the state at the time of erasing. In the figure, 1 is a magnetic head, 2 is an objective lens, 3 is a magneto-optical disk, 31 is the magneto-optical recording medium, 32 is a transparent substrate, arrow R is the rotation direction, and M is the magnetic field during recording and reproduction. The direction M' indicates the direction of the magnetic field during erasing.

First, when recording information, as shown in the upper part of FIG. 9(1), a magnetic field is applied from a magnetic head 1 composed of an electromagnet (in a downward direction indicated by an arrow M), and a beam is focused by an objective lens 2. The laser beam thus generated is irradiated onto the magneto-optical recording medium 31 from below through the transparent substrate 32 of the magneto-optical disk 3. The irradiated laser light is intensity-modulated according to the binary-modulated recording data of "1" and "0",
Only the portion of the magneto-optical disk 3 with high optical power is reversed according to the magnetic field in the direction of arrow M.

[0005] The relationship between recorded data, optical power, and magnetization during recording is as shown in the lower part of FIG. 9 (1), when the recorded data is "1", the optical power is strong and the direction of magnetization is upward. When the recorded data is "0", the optical power is weak and the direction of magnetization is downward. in this way,
The magneto-optical recording medium 31 of the magneto-optical disk 3 is "1", "
According to the recorded data of 0'', it is magnetized upward and downward.

[0006] When reproducing information, a relatively weak power laser beam is irradiated onto the magneto-optical disk 3. Then, the change in the polarization direction of the reflected light caused by the change in the magnetization direction (
By detecting the Kerr effect (commonly called the Kerr effect),
Play recorded information. For example, if a signal (1, 0, 1, 0, ...) in which the direction of magnetization alternates as shown as magnetization is recorded in the lower part of FIG. 9 (1), the reproduced signal will be a sign. The information is reproduced by converting it into a waveform and binarizing it.

On the other hand, when erasing information, FIG.
2) As shown above, a magnetic field is applied from the magnetic head 1 onto the magneto-optical disk 3 in the direction opposite to that during recording (upward indicated by arrow M'), and as shown below in FIG. 9(2), By continuously irradiating strong light, the direction of magnetization is aligned in one direction (upward in the figure). The magnetic head 1 is composed of an electromagnet as schematically shown in the upper part of FIG. 9(1).

Incidentally, in recent years, there has been a demand for larger-capacity memories, and storage media such as optical discs that have information sections that can be recorded and reproduced on both sides have been developed. There is also an increasing demand for devices that can continuously record and reproduce information without any loss. In response to such demands, an apparatus has been proposed in which heads are provided on both sides of the disk.

FIG. 10 is a diagram showing an example of the configuration of a main part near the head of a conventional magneto-optical disk device having information sections that can be recorded and reproduced on both the front and back sides, and a diagram showing the relationship between the signal waveforms. , (1) is the main structure near the head, (2) is the status of each signal on the B side, (3)
is a diagram showing the state of each signal on the A side. In the figure, 1 is a magnetic head, 2A and 2B are objective lenses, 3 is a magneto-optical disk, 31A and 31B are the magneto-optical recording media,
32A and 32B indicate transparent substrates, and M indicates the direction of the magnetic field during recording and reproduction.

[0010] In a magneto-optical disk device having an information section that can be recorded and reproduced on both the front and back sides, as shown in FIG. 10(1), a magnetic field M is applied by one magnetic head 1 provided on the B side. It is. Therefore, the direction of magnetization during recording/reproduction is reversed between the A side and the B side.

That is, the recorded data shown as a recorded signal in FIG. 10(2) is recorded on the magneto-optical recording medium 31A.
, 31B, the reproduced signal on the B side becomes a binary signal in the opposite direction, as shown below. Note that on the A side, as shown in FIG. 10(3), a reproduced signal having the same polarity as the recording signal is obtained.

[0012] In this way, when both sides of A and B are reproduced simultaneously by one magnetic head 1, one of the reproduced signals will be in the opposite direction. Therefore, the magnetization direction during recording/erasing must be switched depending on whether it is the A side or the B side.

However, with this one magnetic head 1, A,
It is impossible to record (or erase) both sides of B at the same time. That is, since one of the reproduction signals of side A and side B is in the opposite direction to the polarity of the recording signal, reproduction signals of opposite polarity cannot be used.

[0014] In order to solve these inconveniences, A.
A possible method is to provide magnetic heads on both sides of B. FIG. 11 is a configuration diagram showing an example of a main part near the head of a magneto-optical disk device having heads on both sides. In the figure, 1A and 1B are magnetic heads arranged corresponding to the A and B sides of the magneto-optical disk 3;
and 2B are objective lenses arranged corresponding to the A and B sides of the magneto-optical disk 3, 3 is the magneto-optical disk, and 31A and 31
B indicates the magneto-optical recording medium, and 32A and 32B indicate transparent substrates.

In FIG. 11, the upper side of the magneto-optical disk 3 is the B side, and the lower side is the A side. Magnetic heads 1B and 1A and objective lenses 2B and 2A are arranged on both sides of this magneto-optical disk 3, respectively. However, in the configuration of FIG. 11, since two magnetic heads are provided, twice as much space is required, which is not a preferable structure from the viewpoint of cost and miniaturization.

The above are the problems with the magnetic head in a conventional magneto-optical disk device having information sections that can be recorded and reproduced on both the front and back sides. Since the polarity is opposite to the signal, it is not possible to record (or erase) both A and B simultaneously with one magnetic head, that is, with only one (one side) magnetic head. Further, if magnetic heads are provided on both sides of A and B, there will be problems from the viewpoint of cost and miniaturization.

By the way, as already mentioned, in recent years, overwritable magneto-optical disk devices using dual-layer media have been announced. When using an overwritable magneto-optical disk with dual-layer media, a strong permanent magnet is required to record/erase on one side of the disk. As explained above, since the polarity of the reproduced signal is reversed on both sides A and B, more problems remain.

FIG. 12 is a diagram showing an example of the structure of a main part near the head of a magneto-optical disk device capable of overwriting using dual-layer media, and a diagram showing the relationship between the signal waveforms. FIG. 2 (2) is a diagram showing the main part structure near the head, and the state of the storage layer and the transfer layer. In the figure, 4 is a permanent magnet, 5A and 5B are objective lenses, and 6
is a magneto-optical disk, 61A and 61B are its transparent substrates,
62A and 62B indicate storage layers, 63A and 63B indicate transfer layers, arrow R indicates the rotation direction, and M indicates the direction of the magnetic field by the permanent magnet 4.

As shown in FIG. 12(1), a magneto-optical disk device using dual-layer media that is overwritable has one permanent magnet 4 on one side of the magneto-optical disk 6, for example on the lower A side. An objective lens 5A is arranged, and an objective lens 5B is arranged on the upper B side. The magneto-optical disk 6 is constituted by a two-layer media including a storage layer 62B (62A) and a transfer layer 63B (63A).

This storage layer 62B (62A) and transfer layer 63
The storage state of information in B (63A) is shown in FIG. 12 (2).
As shown in the figure, the recorded data is “0” on the upper side B.
When , the polarities of the storage layer 62B and the transfer layer 63B are reversed, and when it is "1", the polarities of the storage layer 62B and the transfer layer 63B are the same downward direction. This point also applies to the lower side A.

[0021] In the overwritable magneto-optical disk using this dual-layer media, this transfer layer 63B (
63A) requires a strong magnetic field to align the magnetization direction in one direction. Furthermore, during reproduction, when a laser beam is irradiated, the part of the recorded data corresponding to the magnetic field direction M of the permanent magnet 4 that is "0" is strongly reflected, and the part that is "1" is weakly reflected. In this case as well, the reproduced signals have opposite polarities on both sides of A and B.

Therefore, even with this overwritable magneto-optical disk device using dual-layer media, there is a problem in that both sides cannot be reproduced simultaneously by one magnetic head. As described above, there are conventionally known magneto-optical disk devices that have an information section that can be recorded and reproduced on both the front and back sides, and magneto-optical disk devices that also have information sections that can be recorded and reproduced on both the front and back sides, and that are overwritable with dual-layer media. In disk drives, the polarities of the reproduction signals on both sides of A and B are reversed, so a single head (only on one side) cannot reproduce both sides at the same time.

[0023]

[Problems to be Solved by the Invention] This invention solves a problem that occurs in a conventional magneto-optical disk device having an information section that can be recorded and reproduced on both the front and back sides, that is, the polarity of the reproduced signals on both sides A and B is reversed. This solves the problem of not being able to reproduce both sides at the same time with one head (only one side), and by using a simple circuit, it is possible to reproduce both sides A and B with one head. It is an object of the present invention to provide a magneto-optical disk device that can perform recording and reproducing operations simultaneously.

[0024]

[Means for solving the problems] In this invention, firstly,
In an apparatus for recording and reproducing information on a magneto-optical disk equipped with a medium having information parts that can be recorded and reproduced on both the front and back sides, using a head unique to each side, two heads from the head unique to each side are used. The polarity of one of the reproduced signals is inverted.

Second, in an apparatus for recording and reproducing information on a magneto-optical disk equipped with a medium having information parts that can be recorded and reproduced on both the front and back sides, using a unique head for each surface,
The polarity of one of the two recording signals supplied to the head specific to each surface is reversed.

Thirdly, in the first or second magneto-optical disk device, the means for accommodating the magneto-optical disk includes surface attribute determining means for determining the attribute of the surface of the magneto-optical disk. , the polarity of the reproduction signal or the recording signal is inverted in accordance with the output from the attribute determination means for the surface.

Fourthly, in an apparatus for recording and reproducing information using a unique head for each surface of a magneto-optical disk equipped with a medium having information parts that can be recorded and reproduced on both the front and back sides,
A magneto-optical disk is a disk in which attribute information indicating each surface of a form that causes a predetermined change in the intensity of reflected light is recorded on a specific track. The apparatus is provided with surface attribute determining means for identifying each surface by discrimination, and is configured to invert the polarity of the reproduction signal or recording signal in accordance with the output from the surface attribute determining means.

Fifth, in an apparatus for recording and reproducing information on a magneto-optical disk equipped with a medium having information parts that can be recorded and reproduced on both the front and back sides, using a unique head for each surface,
A surface attribute information recording means that uses a signal that is inverted in a predetermined order as surface attribute information, records/reproduces the surface attribute information, and matches/mismatches the reproduced signal and the recorded signal,
A surface attribute determining means for determining the attributes of the surface of the magneto-optical disk is provided, and the polarity of the recording signal is inverted in accordance with the output from the surface attribute determining means.

[0029]

[Operation] In this invention, since the A/B side of the magneto-optical disk is determined and the polarity of the reproduction signal and recording signal is switched for each side of the A/B side, it is possible to simultaneously record and reproduce both sides with one magnetic head. We are making it possible to do so.

[0030]

Embodiment 1 Next, an embodiment of the magneto-optical disk device of the present invention will be described in detail with reference to the drawings. This embodiment corresponds to the inventions of claims 1 and 3.

FIG. 1 is a functional block diagram showing an embodiment of the main structure of a magneto-optical disk device of the present invention. In the figure, 11 is a cartridge, 11a is a double-sided disc, 12A is an A head section, 12B is a B head section, 13A is a first reproduction signal detection circuit, 13B is a second reproduction signal detection circuit, and 14A is a first reproduction signal detection circuit. Polarity inversion circuit, 14
B is a second polarity inversion circuit, 15 is a demodulation circuit, 16 is a modulation circuit, 17 is a recording signal generation circuit, and 18 is an A/B side discrimination means.

In the magneto-optical disk device of the present invention shown in FIG. 1, details of the magnetic head are omitted to simplify the drawing, but the magnetic head 1 of FIG. 10 described as a conventional example, Permanent magnet 4 and objective lens 5A in FIG.
, 5B. In other words, as shown in FIG. 11, one electromagnet or permanent magnet, that is, one (one side) magnetic head, and two sets of semiconductor lasers or condensing lenses can be used without the need to provide two sets of magnetic heads. It is configured so that recording and reproduction can be performed simultaneously on both sides of A and B.

First, during recording, the recording signal generation circuit 17
A, according to the recording signal sent from the modulation circuit 16,
The lasers of both B heads are driven to record information on each side of the double-sided disk 11a built into the cartridge 11.

Next, during reproduction, the A head section 12A and the B head section 12 disposed opposite to the A/B surface
The signal read from B is binarized by the next first and second reproduced signal detection circuits 13A and 13B. The outputs of the first and second reproduction signal detection circuits 13A and 13B are as follows:
The signals are sent to first and second polarity inversion circuits 14A and 14B, respectively.

FIG. 2 is a diagram showing a specific configuration of the polarity inversion circuit. First and second polarity inversion circuits 14A, 14B
As shown in FIG. 2, is composed of a two-input exclusive OR circuit. Then, if one input of the exclusive OR circuit is the binarized reproduction signal and the other input is the output of the A/B side discriminating means 18, the output of this exclusive OR circuit is When the output of the B side discriminating means 18 is "1", the inverted signal of the reproduced signal is output, and when the output is "0", the reproduced signal is output as is. The first and second polarity inverting circuits 14A and 14B have a configuration as shown in FIG. 2.

[0036] Here, the specific configuration of the A/B side discriminating means 18 will be explained. FIG. 3 shows the cartridge 11 and A
3 is a diagram showing a specific configuration example of the /B-side determining means 18. FIG. In the figure, 11b is an A/B side detection hole provided at one end of the cartridge 11, and 18a is an A/B side discrimination means 18.
This figure shows the switches that make up the main parts of the system.

For example, this switch 18a is in the on state when it is on the A side, and is off when it is on the B side.
The A/B side of the cartridge 11 is determined based on the output, that is, the output of the A/B side determining means 18.

[0038]The first and second polarity inverting circuits 14A
, 14B, the polarity of the input signal is inverted by the output of this A/B side discriminating means 18, so the first and second polarity inverting circuits 14A, 14B output alternately inverted output signals. can get. This alternately reversed first and second
The output signals from the polarity inversion circuits 14A and 14B are supplied to the next demodulation circuit 15 and demodulated.

Therefore, even if recording and reproducing operations are performed simultaneously on both sides of the double-sided disk 11a by using only one magnetic head (on one side), the polarity of the reproduced signal seen from the demodulation circuit 15 will be the same. In this way, among the two reproduction signals from the heads (12A, 12B) specific to the A and B sides,
By reversing the polarity of one reproduction signal, it is possible to reproduce operations on both sides at the same time, unlike conventional magneto-optical disk drives that have information sections that can be recorded and reproduced on both the front and back sides, where reproduction signals cannot be obtained at the same time. This problem is solved.

[0040]

[Embodiment 2] Next, a second embodiment of the magneto-optical disk device of the present invention will be described in detail. This example is
This corresponds to the inventions of claims 2 and 3.

FIG. 4 is a functional block diagram showing another embodiment of the main structure of the magneto-optical disk device of the present invention. The symbols in the figure are the same as in FIG. 1.

In the previous embodiment, the first and second reproduction signal detection circuits 13A,
This configuration inverts the polarity of the output signal from 13B. In this embodiment, the polarity of the recording signal output from the recording signal generation circuit 17 is inverted by the output of the A/B side discriminating means 18.

In this way, even if the polarity of the output signal from the recording signal generation circuit 17 is reversed, the polarity of the reproduced signal will be the same on both sides, so one magnetic head (on one side) can read the double-sided disk 11a. Even if you record on both sides at the same time,
The polarity of the reproduced signal viewed from the demodulation circuit 15 can be made the same.

[0044]

[Embodiment 3] Next, a third embodiment will be explained in detail. This embodiment corresponds to the fourth aspect of the invention.

FIG. 5 is an enlarged view of a main part of the magneto-optical disk device of the present invention showing an embodiment of the state in which pre-pits are formed on the double-sided disk 11a. In the figure, 11
1 is a double-sided disk similar to that in FIG. 1, 11c is its recording track, 11d is a magneto-optical information recording area on the recording track 11c, 11e is a reflected optical signal recording area, 11f is a pre-pit, and L is a laser beam. .

In this embodiment, the reflected optical signal recording area 1 on a specific track 11c on both sides of the double-sided disc 11a is
1e, small holes called pre-pits 11f assigned to surfaces A and B in advance are formed and given as attribute information indicating each surface. Then, a signal representing a change in the intensity of the reflected light of the laser beam L caused by the presence or absence of the pre-pit 11f is detected by a reflected light signal detection circuit, and the A and B surfaces are discriminated based on the result.

FIG. 6 is a functional block diagram showing a third embodiment of the main structure of the magneto-optical disk device of the present invention. The symbols in the figure are the same as in FIG. 1, and 21A is the first reflected light signal detection circuit, 21B is the second reflected light signal detection circuit, 22A is the first A/B information reproducing circuit, and 22B is the 2 shows the A/B information reproducing circuit of No. 2.

In the first and second embodiments described above, the switch 18a and the A/B side discrimination means 18, such as a detection hole, are used to discriminate between the A and B sides of the double-sided disc 11a. In this embodiment, the A/B side is determined by the change in the intensity of the reflected light due to pre-pits 11f formed in advance in the reflected light signal recording area 11e on a specific track 11c as shown in FIG. ing.

The first reflected light signal detection circuit 21A in FIG. 6 detects the reflected light obtained by the pre-pits 11f on the A side of the double-sided disc 11a, and if it is the information on the A side set in advance, the A side is detected. It is determined that Similarly, the second reflected light signal detection circuit 21B detects the reflected light obtained by the pre-pits 11f on the B side and determines that it is the B side.

The first and second reflected light signal detection circuits 21A,
The detection output of 21B is the next first and second A/B, respectively.
The information is supplied to the information reproducing circuits 22A and 22B, and the first and second polarity inverting circuits 14A and 14A correspond to each side of A/B.
The polarity of 14B is controlled.

First and second polarity inversion circuits 14A, 14B
, and the operations of the other circuits are the same as in the case of FIG. In other words, heads (12A, 12B) specific to the A and B sides
By reversing the polarity of one of the two reproduced signals from the two, simultaneous reproduction operations on both sides become possible.

[0052]

[Embodiment 4] Next, a fourth embodiment will be explained in detail. This embodiment also corresponds to the invention of claim 4. the third one
In the embodiment described above, the reproduction operation for both sides at the same time was described. In this embodiment, a recording operation is performed on both sides at the same time, and corresponds to the recording operation in the second embodiment.

FIG. 7 is a functional block diagram showing a fourth embodiment of the main structure of the magneto-optical disk device of the present invention. The symbols in the figure are the same as in FIG. 6. In this FIG. 7 as well, similarly to FIG. 6, the detection outputs of the first and second reflected light signal detection circuits 21A and 21B are transmitted to the next first and second A/B information reproducing circuits 22A and 22B, respectively. The polarities of the first and second polarity inverting circuits 14A and 14B are controlled so as to correspond to each plane of A/B.

In the embodiment shown in FIG. 7, the output of the recording signal generation circuit 17 is supplied to the first and second polarity inverting circuits 14A and 14B, as in the case of FIG. The polarity of the signal is controlled. Other configurations are basically
It is similar to FIG. 4, and the first and second polarity inversion circuits 14A,
The output of the recording signal generation circuit 17 is controlled to be inverted or non-inverted by the output of the recording signal generating circuit 14B.

[0055]

[Embodiment 5] Next, a fifth embodiment will be explained in detail. This embodiment corresponds to the invention of claim 5.

FIG. 8 is a functional block diagram showing a fifth embodiment of the main structure of the magneto-optical disk device of the present invention. The reference numerals in the figure are the same as those in FIG. 1, and 31 is a polarity discrimination signal generation circuit, 32A is a first reproduction signal polarity determination circuit, and 32B is a second reproduction signal polarity determination circuit.

In this fifth embodiment, attention is paid to the fact that the polarity of the reproduced signal on the A/B side is reversed, and the A/B side is changed depending on the polarity.
I am trying to distinguish between faces. To this end, the polarity discrimination signal generation circuit 31 generates a polarity discrimination signal of a predetermined pattern, records the signal, and when reproducing it, the first and second reproduction signal polarity discrimination circuits 32A, 32B
The polarity is determined from the reproduced signal using a polarity determination signal.

For example, if the polarity discrimination signal of a predetermined pattern is (1, 0, 1, 0), if the reproduced signal has the same polarity (1, 0, 1, 0), it will be , if the polarity is (0, 1, 0, 1), it is determined as B. During playback, the first and second polarity inverting circuits 14A, 14A, 32B, 32B, 32B, and 32B operate in accordance with the A/B side discrimination results, that is, the outputs of the first and second reproduction signal polarity discrimination circuits 32A, 32B, respectively.
14B inverts the polarity of the reproduced signal and outputs it to the demodulation circuit 15.

First and second polarity inversion circuits 14A, 14B
has the configuration shown in FIG. 2 above, and the two-input exclusive OR circuit constituting the polarity inversion circuit detects the reproduced signal when the signal indicating the A/B side discrimination result is “1”. The inverted signal is
When it is "0", the reproduced signal is output as is.

In each of the above embodiments, a general magneto-optical disk having recordable and reproducible information portions on both the front and back sides has been described as the magneto-optical disk. However, since it is clear that the same implementation is possible in the case of an overwritable magneto-optical disk using dual-layer media, it goes without saying that the magneto-optical disk device of the present invention includes both. Not even.

[0061]

Effects of the Invention In this invention, in a magneto-optical disk device, since the polarity of the reproduction signal is switched for sides A and B, it is possible to simultaneously record on both sides with one magnetic head, which reduces the cost of the disk device. Cost reduction and size reduction are realized (effects corresponding to the invention of claim 1).

Furthermore, since the polarity of the recording signal is switched for the A/B sides, it is also possible to simultaneously record on both sides with one magnetic head (an effect corresponding to the second aspect of the invention).

[0063] Since the A/B side is determined by the detection hole of the cartridge and the polarity of the reproduction signal and recording signal of the A/B side is switched in accordance with the determined A/B side, similarly,
It becomes possible to simultaneously read or record on both sides with one magnetic head (an effect corresponding to the invention of claim 3).

Furthermore, since the A and B sides are discriminated based on the change signal of the reflected light intensity recorded in advance on the magneto-optical disk, and the polarity of the reproduction signal or recording signal of each side is switched, similarly, one It becomes possible to simultaneously read or record on both sides using a magnetic head (an effect corresponding to the invention of claim 4).

In addition, a predetermined pattern of signals is recorded on the magneto-optical disk, and side A and B are discriminated by comparing the pattern of the reproduced signal and the pattern of the original recorded signal. , the polarity of the reproduction signal for sides A and B is switched, so it is possible to simultaneously read or record on both sides with a single magnetic head, which reduces the cost and size of the disk device ( Effects corresponding to the invention of claim 5), and many other excellent effects can be achieved.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing an embodiment of the main configuration of a magneto-optical disk device of the present invention.

FIG. 2 is a diagram showing a specific configuration of a polarity inversion circuit.

FIG. 3 is a diagram showing a specific configuration example of the cartridge 11 and the A/B side discriminating means 18.

FIG. 4 is a functional block diagram showing another embodiment of the configuration of essential parts of the magneto-optical disk device of the present invention.

FIG. 5 is an enlarged view of a main part of the magneto-optical disk device of the present invention showing an example of a state in which pre-pits are formed on a double-sided disk 11a.

FIG. 6 is a functional block diagram showing a third embodiment of the configuration of main parts of the magneto-optical disk device of the present invention.

FIG. 7 is a functional block diagram showing a fourth embodiment of the configuration of essential parts of the magneto-optical disk device of the present invention.

FIG. 8 is a functional block diagram showing a fifth embodiment of the configuration of essential parts of the magneto-optical disk device of the present invention.

FIG. 9 is a configuration diagram showing an example of a main part near a head of a conventional magneto-optical disk device, and a diagram showing a relationship between the signal waveform.

FIG. 10 is a configuration diagram showing an example of a main part near the head of a conventional magneto-optical disk device having information sections that can be recorded and reproduced on both the front and back sides, and a diagram showing the relationship between the signal waveforms thereof.

FIG. 11 is a configuration diagram showing an example of a main part near the head of a magneto-optical disk device having heads on both sides.

FIG. 12 is a configuration diagram showing an example of a main part near the head of a magneto-optical disk device capable of overwriting using dual-layer media, and a diagram showing the relationship between the signal waveforms thereof.

[Explanation of symbols]

11 Cartridge 11a Double-sided disk 11b A/
B-side detection hole 11e Reflected light signal recording area 11f Pre-pit 12A A head section 12B B head section 13A First reproduction signal detection circuit 13B Second reproduction signal detection circuit 14A First polarity inversion circuit 14B Second polarity inversion circuit 15 Demodulation circuit 16 Modulation circuit 17 Recording signal generation circuit 18 A/B side discrimination means 21A First reflected light signal detection circuit 21B Second reflected light signal detection circuit 22A First A/B information reproducing circuit 22B Second A/B information reproducing circuit 31 Polarity discrimination signal generation circuit

Claims (5)

[Claims] 1. An apparatus for recording and reproducing information on a magneto-optical disk, which is equipped with a medium having information parts that can be recorded and reproduced on both the front and back sides, using a head unique to each side, wherein a head unique to each side is used. A magneto-optical disk device characterized in that the polarity of one of two reproduction signals from a head is reversed. 2. An apparatus for recording and reproducing information on a magneto-optical disk including a medium having information parts that can be recorded and reproduced on both the front and back sides using a head unique to each side, wherein a head unique to each side is used to record and reproduce information. Of the two recording signals supplied to the head,
A magneto-optical disk device characterized by reversing the polarity of one recording signal. 3. The magneto-optical disk device according to claim 1 or 2, further comprising surface attribute determining means provided in the means for accommodating the magneto-optical disk and for determining the attributes of the surface of the magneto-optical disk. A magneto-optical disk device characterized in that the polarity of a reproduction signal or a recording signal is inverted in accordance with an output from a surface attribute determining means. 4. In an apparatus for recording and reproducing information on a magneto-optical disk, which is equipped with a medium having information parts that can be recorded and reproduced on both the front and back sides, using a unique head on each side, the magneto-optical disk This is a disk on which attribute information indicating each surface of a form that causes a predetermined change in the intensity of reflected light is recorded on the track, and each surface is identified by determining the change in the intensity of reflected light on the magneto-optical disk. What is claimed is: 1. A magneto-optical disk device comprising an attribute determining means for a surface to be identified, and inverting the polarity of a reproduction signal or a recording signal in accordance with an output from the surface attribute determining means. 5. An apparatus for recording and reproducing information on a magneto-optical disk equipped with a medium having recordable and reproducible information sections on both the front and back sides using a unique head for each side, in a predetermined order. A surface attribute information recording means that uses an inverted signal as surface attribute information, records/reproduces the attribute information of the surface, and determines the attribute of the surface of the magneto-optical disk by matching/mismatching the reproduced signal and the recorded signal. What is claimed is: 1. A magneto-optical disk device comprising a surface attribute determining means for determining a surface attribute, and inverting the polarity of a recording signal in accordance with an output from the surface attribute determining means.