JPH08161764A - Tilt detection device of optical recording medium, and information recording and reproducing apparatus using the device - Google Patents

Abstract

PURPOSE: To obtain the tilt detection device, of an optical recording medium, which can detect the tilt of the recording medium without a need of a tilt sensor and to obtain an information recording and reproducing apparatus using it. CONSTITUTION: Cross talks of preformatted signals from the outer circumferential direction and the inner circumferential direction of a disk 100 are detected respectively. The tilt of the disk 100 is detected on the basis of the difference between the cross talks obtained from the outer circumferential direction and the inner circumferential direction. In addition, according to a tilt detection amount by a tilt detection device, the inclination of an optical disk 101 which shines an optical beam at the disk 100 is controlled, and a tilt servo operation is performed in such a way that the optical axis of the optical beam becomes perpendicular to the face of the disk.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt detecting device for detecting tilt of an optical recording medium such as a magneto-optical disk and an information recording / reproducing device using the tilt detecting device.

[0002]

2. Description of the Related Art Conventionally, as a device for optically recording or reproducing information, a device for reproducing a reproduction-only recording medium in which information has been recorded in advance, information is formed by opening a recording film with heat. There are a write-once type in which pits are recorded and a rewritable type in which information pits are recorded by changing the direction of magnetization of a perpendicular magnetic film. FIG. 14 is a diagram showing a rewritable magneto-optical disk device.

In FIG. 14, reference numeral 1 denotes a magneto-optical disk (hereinafter simply referred to as a disk) which is an information recording medium.
And is rotated at a predetermined speed by driving a spindle motor (not shown). A bias magnet 2 is provided on the upper surface of the disk 1, and an optical head 14 for irradiating the disk 1 with a light beam and detecting reflected light from the disk 1 is provided on the lower surface. A semiconductor laser 3 as a light source is provided inside the optical head 14, and a laser beam emitted from the semiconductor laser 3 is applied to the disk 1 via a polarization beam splitter 4 and an objective lens 5. At the time of this irradiation, the laser beam of the semiconductor laser 3 is condensed by the objective lens 5 and imaged on the disk 1 as a minute light spot.

A part of the light thus radiated to the disc 1 is reflected by the disc surface, passes through the objective lens 5 again, passes through the polarization beam splitter 4, and enters the polarization beam splitter 6. This incident light is separated into an S-polarized component and a P-polarized component by the polarization beam splitter 6, and the S and P-polarized components are received by the photodiodes 7 and 8 and converted into electric signals. The photodiodes 7 and 8 are composed of a multi-divided sensor whose light-receiving surface is divided into a plurality of parts, and servo control is performed by using the sensor output. That is, the output signal of the photodiode 7 is the preamplifier 9 and the output signal of the photodiode 8 is
Are amplified by the preamplifier 10, and the servo signal generation circuit 11 performs predetermined signal processing using the output signals of the preamplifiers 9 and 10 to generate a focus error signal and a tracking error signal. A servo control circuit (not shown) performs focus control and tracking control of the light spot irradiated on the disk 1 based on these focus error signal and tracking error signal.

Further, the output signals of the preamplifiers 9 and 10 are added by an adder 12 to reproduce a preformat signal recorded on the disk 1 with uneven pits. The obtained preformatted signal is sent to a signal processing circuit (not shown), and the address of the disk 1 is detected. Further, the output signals of the preamplifiers 9 and 10 are subtracted by the subtractor 13, and the information recorded by the pits of perpendicular magnetization on the disk 1 is reproduced as an MO signal. This signal is also sent to the signal processing circuit, and data is reproduced by performing predetermined signal processing. Further, when recording information on the disk 1, a magnetic field is applied to the disk 1 from the bias magnet 2 and the laser beam of the semiconductor laser 3 is emitted from the optical head 14. At this time, by modulating either the magnetic field or the laser beam according to the information signal, the recording layer (perpendicular magnetization film) of the disk 1 is oriented upward or downward according to the information signal, and a series of information is magnetized. It is recorded as information pits in different directions.

When the disc 1 is warped, the optical axis of the laser beam emitted from the objective lens 5 is not perpendicular to the disc 1 and tilts with respect to the disc surface. However, when the tilt is generated in this way, the light spot connecting the focal points on the disc 1 becomes large due to the aberration. Therefore, when the information is being reproduced, the light spot spreads to the adjacent track and is adjacent to the reproduced signal. Crosstalk from the track gets mixed in. FIG. 15 shows such a warped state of the disc 1. FIG. 15A shows a state where the outer peripheral side of the disc 1 is inclined downward,
(B) shows a state where the outer peripheral side of the disk 1 is inclined upward. When the disc 1 is tilted as shown in FIG. 15A, side spots are generated on the outer peripheral side of the track, and crosstalk from the outer peripheral side track is mixed in the reproduced signal. Further, when the disc 1 is tilted as shown in FIG. 15B, side spots are generated on the inner circumference side of the track, so that crosstalk from the inner circumference side track is mixed in the reproduced signal.

Therefore, in order to prevent the crosstalk from the adjacent tracks caused by the tilt of the disk 1, the warp (tilt) of the disk 1 itself is suppressed to a small level.
There is a method of detecting the tilt of the disk 1 and controlling the tilt of the optical axis of the laser beam in accordance with the tilt (tilt servo). However, even if the warp of the disc 1 itself is suppressed, in the case of a magneto-optical disc, the tilt value is 130 mm according to the ISO standard, and it is determined to be 5 mrad or less for a MO of 650 MB, so it is difficult to keep the warp smaller than that. Is.

Further, in order to realize a high density of information on the disc 1 in the future, it is necessary to increase the aperture (NA) of the objective lens to reduce the light spot diameter, but when the NA is increased, the disc is allowed. There is a relation that the amount of tilt that can be achieved becomes smaller, and further considering the productivity of the disc 1, there is a limit to making the tilt standard even smaller. Therefore, if the warp of the disk cannot be suppressed, the method using the tilt servo can only be adopted. In particular, such a tilt servo has already been adopted in a laser disk device in which it is difficult to suppress the tilt of the disk because the disk diameter is as large as 30 cm.

FIG. 16 is a view showing a tilt detecting device in a conventional tilt servo. In the figure, reference numeral 20 is a disk whose tilt is to be detected, and 21 is a tilt sensor for detecting the tilt of the disk 20. The tilt sensor 21 is the disc 2
It is composed of a light emitting diode 22 (LED) that projects light to 0, and photodiodes 23 and 24 on both sides of the light emitting diode 20 that detect reflected light from the disk 1. The received light signals of the photodiodes 23 and 24 are differentially amplified by the operational amplifier 25, and the output signal is output as the tilt detection signal. Here, as shown in FIG. 16, when the disk 20 has no warp and the optical axis of the laser beam is perpendicular to the disk surface, the light receiving signals of the two photodiodes 23 and 24 are the same, so the operational amplifier 2
The tilt detection signal of 5 becomes 0, and it is detected that the tilt is 0. In addition, for example, as shown in FIG.
If 0 is tilted, the two photodiodes 23,
A difference occurs in the light receiving signals of 24, and the operational amplifier 25 outputs a tilt detection signal corresponding to the tilt of the disk 20.

FIG. 18 is a diagram showing a schematic structure of a disk device for performing tilt servo using such a tilt detecting device. In FIG. 18, reference numeral 26 denotes an optical head for irradiating the disk 20 with a laser beam.
A tilt sensor 21 is provided on the top. Further, the optical head 26 is configured so that the optical axis of the laser beam can be tilted. The output signal of the tilt sensor 21 is sent to the tilt detection circuit 27, and in the tilt detection circuit 27, the disc 20
And outputs a tilt detection signal corresponding to the tilt of. The tilt servo circuit 28 controls the tilt of the optical head 26 according to the tilt detection signal, and performs tilt servo so that the optical axis of the laser beam of the optical head 26 is always perpendicular to the disk surface. By performing the tilt servo in this way, the light spot on the disk surface does not reach the adjacent track. Therefore, when the information is reproduced by the signal processing circuit 29,
The influence of crosstalk from adjacent tracks is reduced,
It is possible to obtain a high-quality reproduced signal.

[0011]

However, the above-mentioned conventional tilt detecting device requires a special tilt sensor for detecting the tilt of the disc, and the tilt sensor must be provided on the optical head. for that reason,
When the tilt servo is performed using the tilt sensor in a device that requires high-speed seek such as a magneto-optical disk device as well as being expensive as a component of the tilt sensor, it is necessary to fix the tilt sensor on the optical head. Therefore, there is a problem that the weight of the optical head is increased and the seek time is delayed. Further, when the tilt sensor is fixed on the optical head, it is necessary to make adjustment so that the output of the tilt sensor becomes 0 when the disc and the tilt sensor (optical head) are parallel to each other. There was a problem of this.

The present invention has been made in view of the above conventional problems, and an object thereof is to provide a tilt detecting device for an optical recording medium capable of detecting the tilt of the recording medium without the need for a tilt sensor. It is to provide an information recording / reproducing apparatus using the same.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to detect crosstalk of preformatted signals from the outer peripheral direction and the inner peripheral direction of an optical recording medium, respectively, and obtain the obtained crosstalk from the outer peripheral direction and the inner peripheral direction. This is achieved by a tilt detecting device for an optical recording medium, which detects the tilt of the recording medium based on the difference in the talk.

An object of the present invention is a tilt detecting device for detecting tilt of an optical recording medium in which the positions of the preformatted signals in the radial direction are aligned, and the ID patterns in the preformatted signals are mutually inverted. A track in which a track is adjacent to the outer peripheral side and a track in which the ID pattern is not inverted is adjacent to the inner peripheral side is reproduced, and crosstalk of the preformat signal from the outer peripheral side track in which the ID pattern is inverted is reproduced. And the tracks in which the ID patterns in the preformat signal are inverted are adjacent to each other on the inner circumference side, and the tracks in which the ID patterns are not inverted are adjacent to the outer circumference side,
Detecting the crosstalk of the pre-format signal from the inner track on which the ID pattern is inverted, and detecting the tilt of the recording medium based on the obtained difference between the outer talk and the inner talk. And a tilt detecting device for an optical recording medium.

It is an object of the present invention to provide a tilt detecting device for detecting the tilt of an optical recording medium in which the radial position of a pre-formatted signal is shifted for each zone, and each zone boundary in two adjacent zones. By reproducing each of the tracks, the crosstalk of the preformatted signal from the outer circumferential direction and the crosstalk of the preformatted signal from the inner circumferential direction are detected, and the difference between the obtained crosstalk from the outer circumferential direction and the inner circumferential direction is detected. The tilt detection device for an optical recording medium is characterized by detecting the tilt of the recording medium.

An object of the present invention is a tilt detecting device for detecting the tilt of an optical recording medium in which the radial position of the pre-formatted signal is shifted for each track and reproduces any one of the predetermined tracks. And detecting the crosstalk of the preformatted signals from the outer and inner circumferential directions, and detecting the tilt of the recording medium based on the obtained difference in the crosstalk from the outer and inner circumferential directions. This is achieved by a tilt detection device for a recording medium.

An object of the present invention is to have a tilt detecting device for any one of the above optical recording media, and to control the tilt of an optical head that irradiates the recording medium with a light beam in accordance with the tilt detection amount of the tilt detecting device. By doing so, the tilt servo is performed so that the optical axis of the light beam is perpendicular to the surface of the recording medium.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a diagram showing an embodiment of an information recording / reproducing apparatus of the present invention. In FIG. 1, reference numeral 100 denotes a magneto-optical disk (hereinafter referred to as disk) which is an information recording medium, and rotates at a predetermined speed by driving a spindle motor (not shown). An optical head 101 is provided on the lower surface of the disc 100, and the disc 100 is irradiated with a light beam for recording and reproduction. The optical head 101 has the same internal configuration as the optical head 14 of FIG. 14, but in the present embodiment, a mechanism including a motor for tilting the optical head 101 is provided, and by this mechanism, the optical head 101 is provided.
Is tilted so that the tilt servo is performed so that the optical axis of the light beam to the disc 100 is always perpendicular to the disc surface. A bias magnet (not shown) is provided on the upper surface of the disc 100.

The difference signal and the sum signal from the optical head 101 are sent to the signal processing circuit 102, and the signal processing circuit 102 reproduces the address of the disk 100 and the recorded data based on these signals. It is like this. The difference signal is the output signal (MO signal) of the subtractor 13 in FIG. 14, and the sum signal is the output signal (preformat signal) of the adder 12, and these circuits are omitted in FIG. Further, in FIG. 1, the servo signal generation circuit 11 shown in FIG. 14 is provided, and in the servo control circuit (not shown), focus control and tracking control are performed based on the obtained focus error signal and tracking error signal. Is done.

The tilt detection circuit 103 is a circuit for detecting the tilt of the disk 100 based on the sum signal from the optical head 101. The tilt detection method of the tilt detection circuit 103 will be described later in detail. The tilt detection signal of the tilt detection circuit 103 is sent to the tilt servo circuit 104, and the tilt servo circuit 104 controls an optical head drive motor (not shown) in accordance with the tilt detection signal, so that the tilt detection signal of the tilt detection circuit 103 is obtained. The optical head 101 is tilted so that In this way, the disk 10 is always
Tilt servo is performed so that the optical axis of the light beam of the optical head 101 is perpendicular to 0.

Next, a first embodiment of the tilt detection circuit 103 will be described. First, in this embodiment, the disk 10
0 has a preformatted signal, and this preformatted signal includes an address mark and is recorded by the mark edge recording system. The address mark is assumed to have a relatively long mark. This is a general format when mark edge recording is performed in order to increase the information density in the future. Further, the first embodiment is an example in which the tilt of the disc 100 in which the preformat signals are aligned in the radial direction is detected.

FIG. 2 is a diagram showing a reproduction signal when the preformat signal of the disc 100 is reproduced. FIG. 2C shows the reproduced signal of the whole, in which the reproduced signal of the pre-formatted signal is shown. In the pre-formatted signal, the first ID (address data) indicates the second ID, and here, two IDs are repeatedly recorded on the disc 100. Figure 2
2A is an enlarged view, and FIG. 2B is an enlarged view. An address mark (AM) is recorded at the beginning, and an ID pattern is recorded after that. Here, since the pre-formatted signal is recorded by mark edge recording (NRZI format) as described above, depending on whether the number of 1s in the data indicating the address information is an odd number or an even number, There is a case where the high level and the low level of the ID pattern of No. 2 and the high level and the low level of the second ID pattern of No. 2 match and the case where they are reversed.

FIG. 2 shows a case where the IDs match with each other.
If the number of 1's in the pattern is an even number, then 1 as shown in FIG.
The high level and low level of the second ID pattern and the second ID pattern match. On the other hand, when the number of 1's in the ID pattern is odd, as shown in FIG.
The high level and low level of the second ID pattern will be inverted. Also in FIG. 3, FIG. 3C shows the entire reproduction signal, and the reproduction signal of the preformat signal is shown therein. In addition, FIG. 3 (a) shows one of them.
The second ID is enlarged, and the second ID in FIG. 3B is enlarged.

Here, it is assumed that the preformatted signal of the track being reproduced has an ID pattern as shown in FIG.
Assuming that the preformat signals of the tracks adjacent to both sides thereof are the ID patterns of FIGS. 2 and 3, the preformat signals are arranged as shown in FIG. In FIG.
Track n is the track currently being reproduced and has a pre-format signal as shown in FIG. The n-1 track adjacent to this is the second ID as in the n track.
Is a non-inverted preformatted signal, and the other adjacent track n + 1 has a preformatted signal in which the second ID is inverted as shown in FIG. In FIG. 4, the n−1 track is the inner circumference side and the n + 1 track is the outer circumference side. In such a state, it is assumed that n tracks are scanned with a light spot to reproduce information, and the tilt of the disc 100 causes aberrations in the light spot, which strongly receives crosstalk from the (n + 1) track.

FIG. 5 shows a reproduced signal obtained by scanning the light spot on the n track at this time. FIG. 5 (c)
5A shows a reproduced signal of a preformatted signal, FIG. 5A shows an enlarged first ID pattern therein, and FIG. 5B shows an enlarged second ID pattern in FIG. Focusing on the address mark at the head position of the two IDs, there is no change in the level of the address mark of the first ID in FIG. 5A, but the address mark of the second ID in FIG. It can be seen that the level of is decreased by Δx. This is because the first ID has the same ID pattern on both the n track and the n-1 track, whereas the second ID has the inverted ID pattern on the n + 1 track, and the crosstalk from the n + 1 track. Therefore, as shown in FIG. 5B, the level of the long address mark of the second ID pattern of the n track is lowered. Therefore, since the amount of decrease in this level is the crosstalk from the n + 1 track, it is held as the crosstalk from the outer peripheral direction of the disk 100.

On the other hand, when detecting crosstalk from the inner peripheral direction of the disk 100, as shown in FIG. 6, the second ID pattern of the preformatted signal of the m-1 track with respect to the preformatted signal of the m track. Is inverted,
Second ID of preformatted signal of m + 1 track
Crosstalk from the inner circumferential direction is detected by finding the positional relationship of the preformatted signals of the track that the pattern is not inverted and reproducing the m tracks. That is, contrary to FIG. 4, the m + 1 track in which the second ID pattern is not inverted is adjacent to the outer peripheral side of the m track, and the m-1 track in which the second ID pattern is inverted is adjacent to the inner peripheral side. By reproducing the m tracks under such conditions, crosstalk from the inner circumference side is detected. In FIG. 6 as well, the m−1 track is the inner circumference side and the m + 1 track is the outer circumference side. Therefore, when the light spot is scanned and reproduced on the m track under such a condition, crosstalk from the m-1 track is received, and the level of the address mark of the second ID pattern is lowered as shown in FIG.
Since this decrease in level is the crosstalk from the m-1 track, it is held as crosstalk from the inner peripheral direction of the disk 100.

Here, regarding the relationship between the crosstalk from the outer peripheral direction and the inner peripheral direction of the disc 100 and the inclination of the disc 100, when the disc is inclined as shown in FIG. Crosstalk becomes large, and when the disc is inclined as shown in FIG. 15B, the crosstalk from the inner peripheral side becomes large. If the disc is not tilted at all, the crosstalk from the outer circumference side is the same as the crosstalk from the inner circumference side, and if this state is maintained, the optical axis of the light beam can always be kept perpendicular to the disc surface. it can. Therefore, the tilt of the disc 100 can be expressed by the difference between the crosstalk from the outer circumference side and the crosstalk from the inner circumference side, and the tilt detection circuit 103 uses the difference between the crosstalk on the outer circumference side and the inner circumference side as the tilt detection amount. Then, the tilt servo circuit 104 performs tilt servo by tilting the optical head 101 so that the tilt detection amount becomes zero.

FIG. 7 is a diagram showing the operations of tilt detection and tilt servo of this embodiment. As described above, the tilt detection circuit 103 reproduces the n tracks in FIG. 4 to measure and holds the crosstalk Δx _n from the outer circumference side, and reproduces the m track in FIG. 6 to reproduce the crosstalk Δx _m from the inner circumference side. Measure and hold. Next, the tilt detection circuit 103 calculates Δx _n −Δx _m and outputs the obtained value to the tilt servo circuit 104 as a tilt detection amount. The tilt servo circuit 104 controls the motor that drives the optical head 101, and tilts the optical head 101 so that the tilt detection amount becomes 0, thereby performing tilt servo. Disk 10
The tilt of the optical head 101 is controlled according to the tilt of 0, and the optical axis of the light beam from the optical head 101 is always maintained perpendicular to the disk surface.

As described above, in this embodiment, since the light spot always scans the center of the track by the function of the tilt servo, the information pit can be recorded in the center of the track when the information is recorded, and the information pit can be reproduced when the information is reproduced. The influence of crosstalk from adjacent tracks can be reduced, and the quality of reproduced signals can be improved. Further, in this embodiment, since the disc tilt is detected by the level difference of the crosstalk, a special sensor such as a tilt sensor is not required, adjustment of the tilt sensor with respect to the disc is not required, and the tilt sensor is used. Instead of detecting the tilt of the tilt sensor and the disc indirectly as in the case of
Since the tilt is directly detected from the crosstalk amount included in the reproduction signal, the tilt of the disc can be detected more accurately than in the case where the tilt sensor is used. Further, since it is not necessary to provide a tilt sensor on the optical head and the weight of the optical head does not increase, it can be suitably used for a device such as a magneto-optical disk device that requires high speed seek. Therefore, by using such a tilt detecting device in an information recording / reproducing device, not only is complicated adjustment unnecessary, but it is compact because there is no tilt sensor, and tilt servo is more accurate than when a tilt sensor is used. Further, it is possible to realize an information recording / reproducing apparatus capable of high-speed seek of the optical head.

Since some tracks on which the pre-formatted signals are arranged as shown in FIGS. 4 and 6 are present on the same disc, one crosstalk is detected at the time of disc exchange or normal information reproduction. Then, that value is held, and when the other crosstalk is detected, the difference between the two crosstalks may be output to perform tilt servo. The detection position of crosstalk as shown in FIGS. 4 and 6 may be calculated and found from the reproduced address, but since the disc format is known in advance,
It is desirable to determine the position and store it in the memory of the control unit (not shown) of the apparatus, and detect the crosstalk when the reproducing position becomes the crosstalk detection point to perform the tilt servo.

Next, a second embodiment of the tilt detection circuit 103 will be described. This embodiment is an example of detecting a tilt when the disc 100 is formatted in the zone CAV system. FIG. 8 is a diagram showing a disk of such a zone CAV format format.
00 is divided into a plurality of zones in the radial direction. As a zone CAV format disc, 130 mm, MO 1.3 GB, 90 mm, MO
There is a standard of 230 MB, etc., and in each case, the positions of the preformat signals in the same zone in the same radial direction are aligned as shown in FIG. 8, but the number of preformat signals in one track changes for each zone. Therefore, the position of the preformatted signal in the radial direction is different for each zone. Therefore, in order to detect the tilt of such a zone CAV format disc, two tracks in which the preformat signals at the zone boundaries are deviated are reproduced,
The tilt of the disc 100 is detected by measuring the crosstalk of the preformatted signals from the tracks adjacent to each other.

More specifically, first, as shown in FIG. 8, the outermost a track of the Y zone is scanned with a light spot to reproduce the a track. The arrow in FIG. 8 indicates the scanning direction of the light spot. FIG. 9A shows a reproduction signal of the a track at this time, and the beginning is b at the innermost circumference of the Y + 1 zone.
Crosstalk Δ of preformatted signal from track
b is detected, and after that, the pre-format signal of the a track is reproduced. Therefore, by reproducing track a, crosstalk Δb from the outer peripheral direction can be detected,
Hold the obtained crosstalk value. next,
As shown in FIG. 8, the innermost b track of the Y + 1 zone is scanned with a light spot to reproduce the b track. Figure 9
(B) shows the reproduced signal of the b track at this time. When reproducing the b track, the light spot scans the preformatted signal first as shown in FIG.
As shown in (b), the preformatted signal of the b track is first reproduced, and then the crosstalk Δa of the preformatted signal from the a track of the Y zone appears. In this way, it is possible to detect crosstalk of the preformatted signal from the inner peripheral direction. Of course, hold the obtained crosstalk value. Therefore, Δa and Δb
The tilt of the disk 100 can be detected by the difference between the two, and the tilt servo is performed by tilting the optical head 101 so that the tilt amount becomes zero.

FIG. 10 is a diagram showing the operations of tilt detection and tilt servo of this embodiment. Tilt detection circuit 1 of FIG.
At 03, tracks a and b on the zone boundary are reproduced as described above, and crosstalks Δb and Δa of the preformat signals from the adjacent tracks are measured and held. Next, the tilt detection circuit 103 calculates the difference between Δa and Δb, and outputs the value of Δa−Δb to the tilt servo circuit 104 as the tilt detection amount. Tilt servo circuit 104
Then, tilt servo is performed by tilting the optical head 101 so that the tilt detection signal becomes zero. By performing the tilt servo in this way, the optical axis of the light beam from the optical head 101 can always be maintained perpendicular to the disk surface regardless of the tilt of the disk. As described above, also in this embodiment, it is possible to detect the tilt of the disc without using the tilt sensor as in the first embodiment.
As a result, it is compact and can detect tilt accurately,
Further, it is possible to provide an information recording / reproducing apparatus for high speed seek.

Next, a third embodiment of the tilt detection circuit 103 will be described. This embodiment is an example of detecting the tilt when the positions of the preformat signals of the disc 100 in the radial direction are not aligned. FIG. 11 shows such a disc, in which the pre-format signals of each track are displaced by a fixed amount in the radial direction. Therefore, in order to detect such a tilt of the disc 100, one of the tracks is reproduced, and the crosstalk of the pre-format signal from the tracks on both sides adjacent thereto is detected. Here, it is assumed that the n tracks in FIG. 11 are reproduced, and the n spots are reproduced by scanning a light spot on the n tracks in the arrow direction. 12 (b) and 12 (c)
Is a diagram showing the reproduced signal of n tracks at this time. First, crosstalk Δa of the preformatted signal from the outer peripheral side n + 1 track appears, then the preformatted signal of n tracks is reproduced, and further after that, Crosstalk Δb of the preformatted signal from the n−1 tracks on the circumference side appears.

Here, when the crosstalk from the n + 1 track is large, Δa becomes large as shown in FIG. 12B, and when the crosstalk from the n−1 track is large, as shown in FIG. 12C. Δb becomes large. Therefore,
It is possible to detect the crosstalks Δa and Δb of the preformatted signals from the outer and inner tracks and detect the tilt of the disc 100 by the difference between Δa and Δb. Then, tilt servo is performed by tilting the optical head 101 so that the difference between Δa and Δb becomes zero. FIG. 12A shows the reproduced signal of n tracks when the difference between Δa and Δb becomes 0 in this way. That is, when the tilt servo is working, the crosstalk from the tracks on both sides is the same as shown in FIG.

FIG. 13 is a diagram showing the operations of tilt detection and tilt servo of this embodiment. The tilt detection circuit 103 reproduces a predetermined track as shown in FIG. 13 and measures and holds crosstalks Δa and Δb of the pre-format signals from the outer and inner tracks adjacent thereto. The tilt detection circuit 103 calculates the difference between Δa and Δb,
The value of Δa−Δb is output as the tilt detection amount. The tilt servo circuit 104 tilts the optical head 101 so that the output of the tilt servo detection circuit 103 becomes 0, thereby performing tilt servo. Also in the present embodiment, the tilt of the disc 100 can be detected without the need for the tilt servo sensor as in the first and second embodiments, and by using the tilt servo sensor, the tilt servo can be made smaller and the tilt servo can be performed more accurately. A high-speed seek information recording / reproducing apparatus can be provided.

[0037]

As described above, according to the present invention, the crosstalk of the pre-formatted signal from the outer peripheral direction and the inner peripheral direction is detected, and the difference between the obtained crosstalk from the outer peripheral direction and the inner peripheral direction is detected. By detecting the tilt of the recording medium, the tilt of the recording medium can be detected without requiring a special sensor such as a tilt sensor, and complicated adjustment can be eliminated. Compared with this, the tilt can be detected more accurately. Therefore, it is small because there is no tilt sensor, it is easy to manufacture, and the tilt servo can be performed more accurately than before, and it is not necessary to provide a tilt sensor on the optical head, so the optical head seeks at high speed. be able to.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an information recording / reproducing apparatus of the present invention.

FIG. 2 is a diagram for explaining a preformat signal used in the first embodiment of the tilt detection device of the present invention.

FIG. 3 is a diagram for explaining a preformat signal used in the first embodiment of the tilt detection device of the present invention.

FIG. 4 is a diagram showing a positional relationship of pre-format signals when detecting crosstalk from the outer peripheral direction in the first embodiment of the tilt detecting device of the present invention.

5 is a diagram showing a reproduced signal of a preformat signal when n tracks are reproduced in the positional relationship of FIG.

FIG. 6 is a diagram showing a positional relationship of pre-format signals when detecting crosstalk from the inner peripheral direction in the first embodiment of the tilt detecting device of the present invention.

FIG. 7 is a diagram for explaining a tilt detecting operation and a tilt servo operation in the first embodiment of the tilt detecting device of the present invention.

FIG. 8 is a diagram showing an arrangement state of preformat signals of a zone CAV format of a tilt detection target in the second embodiment of the tilt detection device of the present invention.

9 is a diagram showing a reproduction signal when a preformatted signal at a zone boundary is reproduced on the disc of the zone CAV format shown in FIG.

FIG. 10 is a diagram for explaining a tilt detecting operation and a tilt servo operation in the second embodiment of the tilt detecting device of the present invention.

FIG. 11 is a diagram showing an arrangement state of a pre-format signal of a tilt detection target disk in the third embodiment of the tilt detection device of the present invention.

12 is a diagram showing a reproduction signal when the preformat signal of the disc of FIG. 11 is reproduced.

FIG. 13 is a diagram for explaining a tilt detection operation and a tilt servo operation in the third embodiment of the tilt detection device of the present invention.

FIG. 14 is a diagram showing a configuration of a conventional magneto-optical disk device.

FIG. 15 is a diagram showing how the reproduction light spot spreads when the disc is tilted.

FIG. 16 is a diagram showing a tilt detection device of a conventional example.

17 is a diagram for explaining a tilt detecting method of the tilt detecting device of FIG.

FIG. 18 is a diagram showing a disk device using a conventional tilt sensor.

[Explanation of symbols]

 100 magneto-optical disk 101 optical head 102 signal processing circuit 103 tilt detection circuit 104 tilt servo circuit n, n-1, n + 1 track m, m-1, m + 1 track

Claims (6)

[Claims] 1. The tilt of the recording medium is detected by detecting the crosstalk of the preformatted signal from the outer peripheral direction and the inner peripheral direction of the optical recording medium, respectively, and detecting the difference in the crosstalk from the outer peripheral direction and the inner peripheral direction. A tilt detecting device for an optical recording medium, characterized in that 2. A tilt detecting device for detecting tilt of an optical recording medium in which positions of a preformat signal are aligned in a radial direction, wherein tracks in which ID patterns in the preformat signal are inverted are on the outer peripheral side. Adjacent to, I
The track in which the D pattern is not reversed is reproduced on the track adjacent to the inner circumference side, crosstalk of the preformatted signal from the outer circumference side track in which the ID pattern is reversed is detected, and the preformatted signal is detected. Tracks whose ID patterns are inverted from each other are adjacent to the inner circumference side, and tracks whose ID patterns are not inverted are adjacent to the outer circumference side are reproduced, and the ID patterns are inverted. An optical recording medium characterized by detecting crosstalk of a preformatted signal from an inner track and detecting the tilt of the recording medium based on the obtained difference in crosstalk from the outer circumference direction and the inner circumference direction. Tilt detection device. 3. The tilt detection device for an optical recording medium according to claim 2, wherein the address of the track for detecting the crosstalk is stored in advance in the storage means. apparatus. 4. A tilt detecting device for detecting tilt of an optical recording medium in which a radial position of a pre-formatted signal is deviated for each zone, wherein each track at each zone boundary in two adjacent zones is detected. By reproducing, the crosstalk of the preformatted signal from the outer peripheral direction and the crosstalk of the preformatted signal from the inner peripheral direction are detected, and the recording is performed by the obtained difference in the crosstalk from the outer peripheral direction and the inner peripheral direction. A tilt detection device for an optical recording medium, which detects tilt of a medium. 5. A tilt detecting device for detecting tilt of an optical recording medium, wherein a position of a pre-format signal in a radial direction is shifted for each track, and a tilt detecting device reproduces any one of predetermined tracks to detect a tilt of the optical recording medium. The tilt of the recording medium is detected by detecting the crosstalk of the preformatted signal from the inner peripheral direction and detecting the tilt of the recording medium based on the obtained difference in the crosstalk from the outer peripheral direction and the inner peripheral direction. Detection device. 6. A tilt detecting device for an optical recording medium according to claim 1, claim 2, claim 4, or claim 5, wherein the tilt detecting device is provided in accordance with a tilt detection amount of the tilt detecting device. An information recording / reproducing apparatus characterized by performing tilt servo so that an optical axis of a light beam is perpendicular to a recording medium surface by controlling an inclination of an optical head that irradiates the recording medium with a light beam.