JPH05101397A - Information recording medium and method and device for processing information using it - Google Patents

Abstract

PURPOSE:To improve optical spot followup ability and recording density by using a track displaced slightly in the directions of scanning the track and in the direction of a depth, performing respective processes to two groops of a regenerative pulse column from the front edge and back edge of a recording pit respectively and independently, thereafter, synthesizing them again. CONSTITUTION:By using a wobble track displaced slightly in the directions of scanning the track and the depth on the disk 1, a data pit is recorded. By heightening the displacement frequency of the track than the control frequency of an optical spot, tracking is controlled by an actuator 17, etc. Further, the data from the front edge and rear edge of the data pit is inputted an edge detection circuit 19 through an actuation converter 18 and front and back edge regenerative pulses 46, 47 corresponding to the data are outputted. After these pulses 46, 47 are processed with regenerative clock generation and with some processes respectively and independently in a regenerative data synthesizing circuit 222, are synthesized to a normal data column again. Thus, the optical spot followup ability and the recording density are improved.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an information processing device,
In particular, the present invention relates to an information processing device that records / reproduces information at high density and performs stable tracking.

[0002]

2. Description of the Related Art In an optical information processing apparatus, various techniques have been proposed for accurately tracking information during high density recording and reproduction.

As an example of high-density recording, an information processing apparatus disclosed in Japanese Patent Laid-Open No. 2-183471 is an optical information processing apparatus for recording / reproducing information by associating information with leading and trailing edges of recording pits. Proposed. This is the fluctuation of the pit edge position that is allowed during data recording, that is,
The leading and trailing edges are adjusted to compensate for variations in the recording length from the normal length caused by variations in recording power and recording pulse width, variations in recording medium sensitivity, variations in recording / reproducing light spot intensity distribution, etc. The playback clocks are generated independently from each other, the playback pulses and the playback clocks for the leading edge and trailing edge sequences are obtained, and they are stored in the memory so that the leading edge and trailing edge pulse intervals are regular pulse intervals. Therefore, the data is reproduced by the identification clock.

Further, as an example of accurately tracking information, there is an information processing apparatus described in JP-A-60-167129.
In the optical disk medium described here, the track guide groove is displaced (wobbled) in the track scanning direction. When such an optical disk medium is used, the track offset amount can always be detected even when the track is followed, and the offset amount can be corrected.

[0005]

Although methods for individually solving the problems relating to high-density recording and accurate track tracking have been disclosed as described above, there has been no information processing measure for simultaneously solving these problems.

Further, it has been found that there are the following problems when an information processing apparatus is constructed by combining the above-mentioned conventional techniques. In an information processing device using a recording medium having a wobble track, recording of data pits is generally performed.
The light spot position for reproduction scans an average position with respect to the displacement of the wobble track, and the light spot appears to be wobbled from the track side.
Therefore, since the distance between the data pit and the track guide groove changes in the wobble cycle, the relative distance relationship between the data pit and the wobble track guide groove changes at the wobble frequency. Therefore, the amplitude and phase of the reproduction signal with respect to the data pits undergo similar changes. Therefore, when the pit edge recording method is used for the medium provided with the wobble track, the pit length changes corresponding to the wobble frequency, and it becomes difficult to reproduce an accurate edge position. That is, stable light spot position control (tracking) and high-density recording cannot be achieved at the same time.

A first object of the present invention is to perform pit edge recording on a medium having a wobble track to realize stable light spot control and high density recording / reproducing. A second object of the present invention is to realize an information processing apparatus capable of reproducing a signal accurately without being affected by the shift of the pit edge position.

[0008]

An information processing apparatus for solving the above problems can be achieved by performing pit edge recording on a medium having wobble tracks. Data pits are recorded on or between the track guide grooves using a wobble track displaced in the track scanning direction to stabilize the light spot position, and the displacement frequency of the wobble track is set higher than the control frequency of the light spot. To perform tracking control. For fluctuations in the pit edge position during recording that occur during reproduction of high-density recorded data, reproduction pulses detected from the leading edge side and the trailing edge side of the data pit are generated as separate system reproduction clocks. After inputting to the system and independently generating the recovered clock, based on the data interval of the known pattern in the data (for example, synchronization pattern, demodulation start pattern, etc.), independently processed front edge side and rear edge side The regenerated pulse train of is combined again with the regular data train. This is because the reproduction clock is generated from the reproduction pulse train, so that a single reproduction clock generation system cannot follow a rapid change in the front edge pulse and the rear edge pulse. Then, a PLL (Phase Locked Loop) is used as the reproduction clock generation means, and its response band is set higher than the wobble frequency.

Further, the offset correction by wobbling is similarly applied to the track depth direction.
In this case, if the displacement in the depth direction is alternated for each adjacent track, the influence of thermal interference between the adjacent tracks can be reduced.

[0010]

In the wobble track slightly displaced in the track scanning direction, the track offset amount is always detected and corrected even when the light spot is scanning the track. Similarly, the amount of defocus is always detected using the track slightly displaced in the track depth direction and is corrected. When the above means is used, the recording pit length is modulated by the wobble frequency and the pit length appears to be expanded or contracted from the viewpoint of recording and reproduction, but this effect corresponds to the leading edge and the trailing edge of the pit. It is possible to remove the reproduction pulses by inputting them to independent reproduction clock generation systems, forming two series of data strings, and then reconstructing based on the known bit arrangement of the specific pattern portion. Therefore, both high-density recording / reproduction and accurate tracking can be realized at the same time. Further, by making the minute displacement in the track depth direction alternately in the opposite phase for each adjacent track, it is possible to reduce the influence on the recorded pits due to the thermal interference which is a problem in the thermal recording medium. Further, a PLL (Phase Locked Loop) circuit is used for the reproduction clock generation means, and its response band is made higher than the wobble frequency. As a result, the noise band of the PLL circuit can be narrowed, and it is possible to prevent hypersensitivity to defects on the disk, so that wobble fluctuations can be more accurately tracked, and the effects of servo fluctuations and wobbling can be reduced. It is possible to suppress the data pit length and the edge position variation due to.

Further, even in an optical system for scanning two or more light beams on the same track, by using the wobble track, it becomes possible to control the position not by the conventional diffracted light tracking but by the change of the reflected light amount. ,
It is possible to realize a system that simplifies the servo system and that does not easily cause an offset even with respect to the aberration of the light spot and the tilt of the disc.

[0012]

EXAMPLES Examples of the present invention will be described below. Figure 1
It is a device block diagram for explaining one Example of the present invention.
The basic structure of the device is the optical disk used for recording and reproducing information, the optical head, the tracking servo circuit system corresponding to the wobble track, the reproducing circuit system for the front edge reproducing pulse of the recording pit, the rear edge reproducing circuit system, and the reproducing pulse train for both of them. It consists of a synthetic circuit system. In FIG. 1, a tracking servo system for a wobble track slightly displaced in the scanning direction of the track will be mainly described. If the focus servo system has the same configuration as that of the tracking servo system shown in FIG. 1, it is possible to constantly detect and correct the offset in the focus direction (generally, the vertical swing direction of the disk).

In FIG. 1, it is assumed that a change in disk reflectivity is used as the recording form of the recording medium. Specifically, a hole-punching (write-once) medium, a phase change medium and the like can be mentioned. Even with other types of recording media, the same processing can be performed with the configuration of the present invention if the reproduction information is converted into light intensity by the photodetector for signal detection. For example, in the case of a magneto-optical medium, the rotation of the polarization plane depending on the direction of perpendicular magnetization is the same after being converted into a change in light intensity by an optical element such as an analyzer that selectively passes only a certain polarization component. Can be treated.

In FIG. 1, information tracks are provided on the disc 1 in a concentric or spiral fashion for recording and reproducing data. The track has a servo band frequency for track following in the track scanning direction,
Moreover, it is slightly displaced at a frequency equal to or lower than the reproduction signal frequency. Furthermore, by providing minute displacements in mutually opposite phases with respect to the depth direction for each adjacent track, it is possible to detect and correct the focus offset during automatic focus control. A specific example of the wobble track form on the disc will be described later.

A light beam from a light source 2 such as a laser passes through a lens 3 and an optical element 4 such as a half mirror or a prism, and is focused on an information surface on the disk 1 by a focusing lens 5. The reflected light modulated by the data pits on the track of the disk 1 is reflected again by the optical element 4 and converted into an electric signal by the photodetectors 6-1 and 6-2. The photodetectors 6-1 and 6-2 are divided along the track direction, and their outputs are input to the adder 7 and the differencer 8, respectively.

For recording data on the write-once type optical disc, the light source 2 is modulated in accordance with the modulated data so that the optical power becomes higher than that at the time of reproduction, the temperature of the recording film of the disc 1 is raised, and the heat is generated. This is performed by melting and evaporating the recording film to form pits. In the case of phase change type optical disc,
Recording is performed by changing the refractive index of the recording film depending on how the heat applied by the light spot is applied. In the case of a magneto-optical disk, a perpendicular magnetization film is used as the recording film, and the magnetization direction is set either above or below the recording film surface by the heat applied by the light spot. In the data reproduction, in the case of the write-once type and the phase change type, the presence or absence of pits is detected as a direct change in the amount of light reflected from the disk recording surface. In the case of a magneto-optical disk, the presence or absence of a data domain can be detected by converting the fact that the polarization plane of the incident light on the recording film rotates according to the magnetization direction due to the magneto-optical effect into a light intensity change by an optical element such as an analyzer. Detect. The detection of the data pit is obtained from the output 40 of the adder 7. In the case of a magneto-optical disk, the detection of the data domain can be similarly discussed by using the signal converted into the above-mentioned light quantity.

FIG. 2 is a diagram for explaining a tracking method when a wobble track is used. This will be described below with reference to FIGS. 1 and 2. The sum signal output 40 is input to the synchronizing circuit 9 and the filter 13. Now, the case where the light spot scans on the average center line of the wobble track is shown in (a). At this time, the difference signal 41 passes through the zero point when the light spot is located at the track center.
On the other hand, the sum signal 40 takes the maximum value at this time. In the present embodiment, since the case of tracking on a flat area between the track guide grooves is considered, the reflected light from the disk becomes maximum at the moment when the light spot position is at the center of the flat portion. , The sum signal 40 takes the maximum value. Here, consider a case where the light spot position is displaced downward in the drawing as shown in FIG. The maximum value of the sum signal 40 at this time changes so that the phase is shifted as compared with (a). Similarly, the zero point of the difference signal 41 is also displaced from that in (a). An actuator 17 for tracking to correct this deviation
Is driven to control the position of the lens 5. Here, the frequency of the sum signal 40 is twice the frequency of the difference signal 41 and the wobble frequency. Sum signal 4
0 is input to the synchronizing circuit 9, detects a certain reference position on the disk, and recognizes that the wobble cycle has started from this point. As a means for indicating this certain reference position, a long pit (mark) that does not exist in the data, or a portion without a track guide groove (mirror surface portion) can be used. The filter output 42 is a signal that has passed near the wobble frequency with respect to the sum signal 40. on the other hand,
The filter 13 is also a bandpass filter for the wobble frequency. A result obtained by multiplying the output 42 and the output 44 by the multiplier 11 is obtained as a multiplication output 43. FIG. 2 shows an output signal waveform in the case where the light spot position is displaced as shown in (b). In this case, the output 43 becomes a signal having a negative polarity, and this signal is used as the gain corrector 1.
After the signal has an appropriate level at 2, the adder 14 adds it to the differencer output 41 to generate a tracking servo control error signal. The error signal output 45 is phase-compensated by the phase compensator 15, and then the driver 16 drives the actuator 17 to control the position of the lens 5.
Even when the light spot is deviated from the track as shown in (c), the multiplication output 43 has the opposite polarity in the same manner.
Control is performed.

In FIG. 1, in detecting the data signal, the outputs 101 and 102 of the differential converter 18 are connected to the edge detection circuit 19.
Input to the playback pulse corresponding to the leading edge and the trailing edge,
By obtaining the pulse 46 and the pulse 47, respectively, and processing them by the reproduction data synthesizing circuit, the front and rear edge data are independently processed, and the original data string is restored. Details of the operation of this part will be described later.

FIG. 3 is a diagram showing the relationship between the pits or domains recorded on the wobble track and the reproduction pulse obtained therefrom. The data pit shall be recorded in the flat portion between the track guide grooves. The same can be said when recorded on the guide groove. The pit edge recording method is used as the data recording method. In the pit edge recording method, the code word data is made to correspond to the front edge and the rear edge of the pit, and the shift of the edge position due to the inter-waveform interference occurs until the edge interval approaches to the half of the effective diameter of the reproduction spot. Absent. Therefore, the linear recording density can be increased as compared with the conventional recording method in which the code word data is associated with the center position of the pit. Incidentally, the distance between the pit centers where the edge shift does not occur in the conventional recording method is given by the sum of the half spot effective diameter and the pit diameter.

Now, when the edge position of the recording pulse is given as shown in the figure, when a pit is recorded on the wobble track, the wobble frequency, that is, the displacement frequency in the track scanning direction, is track-following for position control of the light spot. Since it is higher than the servo frequency, the pit position seems to be wobbled from the center of the track. Therefore, since the distance between the pit and the track guide groove changes every moment, the pit length detected from the reproduced waveform appears to be extended or reduced due to the influence of the groove. Specifically, as shown in the edge pulse train of the reproduced waveform in the figure, it is observed that the pit length changes corresponding to the wobble period. Further, the tracking (response) band of a PLL (Phase Locked Loop) circuit that generates a reproduction clock from a reproduction pulse train is set lower than the reproduction pulse frequency of the recording data. By narrowing the response band of the PLL circuit in this way, the noise band of the PLL circuit itself can be narrowed, and at the same time, it is possible to prevent a hypersensitive response to defects on the disk. Further, even if the pit length is extended or reduced, the edge is not shifted, and a large reproduction error does not occur. In the conventional method, for example, when a front edge pulse and a rear edge pulse at the time of reproduction are input to a single reproduction clock generation system as in Japanese Patent Laid-Open No. 62-254514, the speed of each edge as shown in FIG. Since the PLL circuit cannot follow the change, it is treated as a shift when viewed from the data detection window generated from the reproduction clock.

Therefore, the above-mentioned shift can be eliminated by separating the front edge pulse and the rear edge pulse by the method described later and treating them as separate signal pulse trains. That is, in each of the leading edge pulse and the trailing edge pulse, only the component that changes at the wobble frequency remains. In the figure, the phase shift waveform (Δ1) of the front edge pulse of the reproduction pulse is shown with respect to the front edge pulse of the recording pulse. The same applies to the phase shift (Δ2) on the trailing edge side. Since the frequency (wobble frequency) of this fluctuation component is sufficiently lower than the response frequency of the PLL circuit system, it can be followed by the PLL circuit system. Numerical examples of various tracking bands (response bands) are given below. The tracking servo band is 1 to 3 kHz and the wobble frequency is 20 to 4
0 kHz, the PLL band is 200 to 400 kHz, and the reproduction signal frequency is about several MHz to several tens of MHz. In this way, by handling the front and rear edges independently, it is possible to reduce the fluctuation frequency on the order of several MHz for each pit to a wobble frequency, so that it is possible to follow up by the PLL system. As a result, it is possible to solve the fluctuation of the pit length during reproduction, which is a problem in the wobble track method effective for detecting and correcting the track offset.

FIG. 4 shows an example of a specific configuration from the output 40 of the adder 7 to the synthesis of the reproduction data 130.
5 is a diagram for explaining the operation of FIG. The case where the pit edge recording method is used as the information pit recording method will be described. The output 40 is output by the differential converter 18 as the differential signals 101 and 102 to the buffer 200.
Entered in. This reproducing circuit system is described as a differential signal system. The reproduction signals 101 and 102 correspond to the presence or absence of pits recorded on the disc, for example, and generally, in the pit portion, the level of the reproduction signal is lower than the unrecorded level due to the decrease in reflectance. The output of the buffer 200 is the differentiator 2
01 is input to obtain a differential signal. After that, the low-pass filter 203 is amplified to an appropriate level by the amplifier 202.
After passing through, the signal is input to the buffer 204 again, and the first-order differential signals 102 and 103 are obtained as outputs. In edge recording, the positive and negative peak positions of the first-order differential signal correspond to the front edge and rear edge positions of the reproduced signal, respectively. Differentiate again to obtain this peak position. After being differentiated by the differentiator 205, it passes through the amplifier 206, the low-pass filter 207, and the buffer 208 to obtain the second-order differential signals 104 and 105.
The zero-cross point of the second-order differential signal is the first-order differential signal 102,
It corresponds to the peak position of 103. Comparators 209, 2
First-order differential signals 102 and 103 are input to 10 to generate gate pulses 108 and 109. Here, the slice level 106 is a threshold value for generating the gate pulses 108 and 109, and is to prevent erroneous pulses generated from other than the zero-cross position of the second-order differential signal from being recognized as data. The gate pulses 108 and 109 are input to the set (S) and reset (R) of the flip-flop 211, respectively, and the pulses 110 and 111 are obtained as outputs (Q). On the other hand, 2
The differential signals 104 and 105 are input to the slice setter 212. The comparator 213 is a differential comparator and has a pulse 1
14 and 115 are output. In addition, flip-flop 2
Pulse 114 to trigger 14 (T)
And 115, and flip-flop 21
The pulses 110 and 111 are input to Nos. 4 and 215. As a result, pulse 1 is triggered by the rising edge of pulse 114.
The pulse 116 is obtained by taking in 10 and resetting in the “H” level state of the pulse 111. The same applies to the pulse 117. The pulse 119 is obtained by taking the logical product of the inversion pulse of the signal 118 obtained by delaying the pulse 116 by the delay element 216 and the original pulse 116. Similarly, a pulse 121 is obtained by taking the logical product of the inversion pulse of the signal 120 obtained by delaying the pulse 117 by the delay element 217 and the original pulse 117. Both of the data pulses 119 and 121 are pulses corresponding to the leading edge and the trailing edge, respectively, and are synthesized by the reproduction data synthesizing circuit 222 and then reproduced data 1
30 and a clock 131 synchronized therewith are obtained as outputs and data demodulated.

Next, an example of a sector format for synthesizing reproduced data will be described. FIG. 6 shows an example of the format configuration of a certain sector, which is roughly divided into a preformat area 400 and a data area 401. The pre-formatted area 400 is classified into a sector mark 410 indicating the beginning of a sector, a VFO synchronization pattern 411 for reproducing clock generation, a track address, and an address area 412 in which the sector address is recorded. User data is recorded in the data area 401. The data area 4
In the configuration of 01, the VFO synchronization pattern 420, the user data demodulation start pattern 421, the user data 422, and the resynchronization pattern 423 for resynchronizing the bit shift of the reproduction clock exist in the user data.

Reproduction data synthesis is performed using a specific pattern in the above format. Here, the case where the VFO synchronization pattern is used will be described. The VFO sync pattern generally uses a certain repeating pattern. FIG. 7 shows the relationship between the codeword pattern of the VFO synchronization pattern 420 and the corresponding pit 430. Ideally, as shown in (a), the code word "1" is recorded corresponding to the front edge and the rear edge of the pit. Actually, as shown in (b), they do not match due to changes in the characteristics of the recording medium and the recording conditions. Since the VFO synchronization pattern is known, if the reproduction pulses 121 and 119 can be corrected to the normal positional relationship, accurate reproduction can be realized for the pattern sequence following this even in the state of (b). According to the present invention, the reproduction pulses 121 and 119 are provided in separate VFOs.
Input to the circuit to generate the recovered clock,
The pattern in the area where the pull-in is stable in the latter half of the synchronization pattern 420 is used as a reference pattern for reproducing data synthesis, and two series of reproducing data strings are stored in the memory so as to have a regular bit arrangement order. .. This enables stable data demodulation even when the edge position of the pit exceeds the data detection window width.

8 and 9 show a configuration example of the reproduction data synthesizing circuit 222 and its operation time chart. Synthesis circuit 22
2 is a two-series VFO circuit 6 for the front edge and the rear edge
00, 601, pattern detection circuits 602, 603, and write address control circuits 604, 605 for registers A, B, register A 606, register B 60.
7 and a data generation control circuit 608.

The leading edge data pulse 121 is input to the VFO1 circuit 600, and a VCO clock 501 and data (DATA1) 502 synchronized with the VCO clock 501 are obtained. Similarly, from the trailing edge data pulse 119 to VFO
The VCO clock 503 and the data (DATA2) 504 are obtained by the two circuits 601. In FIG. 9, the data is shown to be valid on the falling edge of the corresponding clock. Data and clock are pattern detection circuit 60
2, 603, and the pattern detection signals 505, 50
6 is output. The pattern detection circuits 602 and 603 output data "1" immediately after the pattern detection signals 505 and 506 are output, as detection pulses 507 and 510, respectively. As a circuit example, a D flip-flop is used, and the flip-flop is set by a detection signal 505, and the data 502 immediately after the output becomes “H”.
When it becomes "H", it should be output. The same applies to the detection pulse 510. The address 508 of the register A606 starts counting up when the detection pulse 507 is input. Similarly, the address 511 of the register B607 is the detection pulse 51
The count-up starts from the time when 0 is input. Register A 606 and register B 607 are serial input,
It is a parallel output memory. Register B here
The write address 511 of 607 is started from "3" because the VFO synchronization pattern uses a repeating pattern of "100". In the number of clocks, data "1" exists for three clocks. This write start address 511 is the V to be used.
Determined by the FO sync pattern. In this way, when the data written in the register A and the register B are read at the common address, the reproduction / synthesis is completed. When the address 511 of the register B activated by the detection pulse 510 from the output control circuit 608 is counted up to "4", the data generation permission signal 514 is generated, and the following data string is reproduction synthesis completed. Output of registers A and B 509, 51
By sequentially reading 2 at the common address 513, the data 130 can be obtained. As the clock 131, the clock 501 may be used. Further, the clock 503 or the recording clock used at the time of recording data can be used.

FIG. 10 shows a structural example of an optical head in the information recording / reproducing apparatus according to the present invention. In the device configuration of FIG.
Although the case of one beam is shown, FIG. 10 shows a configuration example of two beams.

FIG. 10 shows an optical head equipped with two laser light sources having different wavelengths. The light emitted from the laser light source 1001a having the wavelength λ ₁ is collimated by the collimator lens 1002.
The beam becomes a parallel light beam at a, and the beam shaping optical system 1003a, the wavelength filter 1004, the polarization beam splitter 1007,
The light passes through the wave plate 1008 and the focusing lens 1009 and is focused on the disk 1010. On the other hand, the light emitted from the laser light source 1001b having the wavelength λ ₂ becomes a parallel light flux by the collimator lens 1002b, and the beam shaping optical system 100
After passing through 3b, the traveling direction is changed by the rotating mirror 1005, and after passing through the diffraction grating 1006, the wavelength filter 10
At 04, it is combined with the laser beam having the wavelength λ ₁ . After that, it passes through the polarization beam splitter 1007, the wave plate 1008, and the focusing lens 1009, and is focused on the disk 1010. Beam shaping optical systems 1003a and 1003 in the figure
003b may be omitted.

The wave plate 1008 is set so that the resulting phase difference is approximately an integral multiple of the wavelength of one of the two light sources, and is approximately ¼ wavelength for the other light source. Has been done. As the wavelength of the light source, for example, a wavelength λ ₁ is around 780 nm, and a wavelength λ ₂ is approximately 680 nm.
Consider a case where the former is used to record information and the latter is used to perform error check after recording using the vicinity. At this time, the phase difference of the wave plate is set to two wavelengths with respect to the wavelength of 680 nm (λ
= 2λ plate with 680 nm). Since the phase difference is an integral multiple of the wavelength, a substantial phase difference does not occur even when light having a wavelength of 680 nm passes through this wave plate. On the other hand, when light having a wavelength of 780 nm passes through this wave plate, the following phase difference occurs.

2 × (780−680) /780=0.256λ That is, for light having a wavelength of 780 nm, it acts as a substantially ¼ wavelength plate.

In this embodiment, information is recorded at a spot having a wavelength of 780 nm, reproduction of recorded information is performed at a spot having a wavelength of 680 nm, and an error check is performed (however,
(For example, address information that is not recorded as a magneto-optical signal is reproduced at both spots). In this case, the wavelength 78
It is preferable that the light utilization efficiency of the 0 nm light beam is as high as possible. Therefore, for the light flux having the wavelength of 780 nm, the configuration of the conventional optical head for the write-once type optical disc is preferable. on the other hand,
To reproduce the spot magneto-optical signal with a wavelength of 680 nm,
The configuration of the conventional optical head for a magneto-optical disk is preferable. In order to realize the former optical system, 1 /
It is sufficient to insert a four-wave plate, but since the disk is irradiated with circularly polarized light, the conventional method cannot reproduce the magneto-optical signal.

Now, the wavelength plate according to the present invention is narrowed down and inserted into a light beam, and a component which satisfies the following characteristics is used for the polarization beam splitter 1007, and an optical system is made to enter the p-polarized light beam into this. If set to, wavelength 780
A conventional write-once optical disk optical head can be simultaneously realized for a light flux of nm, and a conventional magneto-optical disk optical head can be simultaneously realized for a light flux of a wavelength of 680 nm.

P-polarized light transmittance Tp: ˜70% (λ = 680n
m)> 90% (λ = 780 nm) s-polarized reflectance Rs:> 95% (λ = 680,
780 nm) A polarizing beam splitter having the above optical characteristics can be realized.

As described above, in the optical head for an optical disc in which a plurality of light sources having different wavelengths are mounted, the optical characteristics (reflectance, transmittance, etc.) of the mounted optical parts are determined according to the roles of the light spots. Different values can be set for the wavelengths corresponding to the spots.

In this embodiment, as shown in FIG. 10, the diffraction grating 1006 is arranged between the wavelength filter 1004 and the rotating mirror 1005. With this configuration, the distance between the diffraction grating 1006 and the focusing lens 1009 becomes large. Therefore, if a so-called three-spot method, which will be described later, is used as a track deviation detection method, an offset is added to the track deviation detection signal due to sub-spot eclipse. There is a disadvantage that occurs. However, the wavelength filter 10
Since 04 and the polarization beam splitter 1007 can be integrated, there is also an advantage that the optical system can be downsized.

The diffraction grating 1006 is replaced by the wavelength filter 1004.
And the polarization beam splitter 1007. In this case, as the diffraction grating 1006, an element in which the depth of the grating or the like is set so that the phase difference generated by passing through the grating is an integral multiple of one wavelength may be used. For example, if the grating structure is set such that the phase difference is an integral multiple for a light beam with a wavelength of 780 nm, the diffraction grating acts as a diffraction grating for a light beam with a wavelength of 680 nm, but a light beam with a wavelength of 780 nm is used. Does not act as a diffraction grating. As a result, it is possible to suppress the generation of unnecessary narrowed spots on the disc 1010. With the above configuration, the diffraction grating 1
Since the distance between 006 and the focusing lens 1009 can be made relatively short, it is preferable to the embodiment of FIG. 10 from the viewpoint of the occurrence of the offset in the above-described track deviation detection signal. However, in such a configuration, since the wavelength filter 1004 and the polarization beam splitter 1007 need to be separately arranged, it is not necessarily preferable from the viewpoint of downsizing the optical system and reducing the number of parts.

When the diffraction grating 1006 is arranged between the polarization beam splitter 1007 and the stop lens 1009, the distance between the diffraction grating 1006 and the stop lens 1009 becomes the shortest. Therefore, from the viewpoint of the offset generation in the track deviation detection signal described above, 2 are preferable. However, with this configuration, since the reflected light from the disk 1010 passes through the diffraction grating 1006 again, a plurality of unnecessary light beams enter the detection optical system, which makes it difficult to separate the light beams in the detection optical system. is there. that's all,
Three examples have been given regarding the position of the diffraction grating 1006.
It is necessary to select this from the viewpoints of downsizing of the optical system, occurrence of offset in the track deviation detection signal, light beam separation in the detection optical system, and the like.

FIG. 11 shows an example of the arrangement of narrowed spots on the disc in this embodiment. A meandering guide groove is formed on this disc to guide the light spot, and each spot is narrowed down to the land portion between the grooves,
Information is recorded on the land portion between the grooves. Since the light flux of wavelength λ ₁ does not pass through the diffraction grating, the spot on the disc is S
Pa is one. On the other hand, since the light flux having the wavelength λ ₂ passes through the diffraction grating, the ± first-order diffracted light SP other than the 0th-order light SPb ₀
b + ₁ and SPb- ₁ are narrowed down.

The reflected light from the disk 1010 passes through the stop lens 1009 and the wave plate 1008, is reflected by the polarization beam splitter 1007, and is detected by the signal detection optical system 101.
Is led to 1. Here, a focus shift signal, a track shift signal, a recording information signal, etc. are detected. First, the wavelength is separated by the wavelength filter 1012. The light flux having the wavelength λ ₂ passes through the wavelength filter 1012 and the lens 1013, and the polarization direction is rotated by about 45 degrees by the λ / 2 wavelength plate 1014.
Then, the Wollaston prism 1015 splits the light into two light beams, which are then incident on the photodetector 1016. On the other hand, the light flux having the wavelength λ ₁ is reflected by the wavelength filter 1012 and transmitted through the lens 1017. Then beam splitter 101
8. Light detectors 1019a and 1019 for separating the light flux by 8 and detecting a focus shift signal or a track shift signal.
incident on b. In the configuration of FIG. 10, the polarization beam splitter 1007 and the wavelength filter 1012 are integrated to reduce the number of parts. Further, by disposing a lens between the polarization beam splitter 1007 and the wavelength filter 1012, the lenses 1013 and 1
It is also possible to replace both lenses with one lens.

FIG. 12 shows an example of the shape of the light receiving surface of each photodetector. FIG. 10A shows the shape of the light receiving surface of the photodetector 1016 (the light receiving surface is a shaded portion), and the track deviation signal TR (so-called 3-spot method) and the magneto-optical signal MO are calculated by the illustrated calculation.
Is obtained. When the λ / 2 wavelength plate 1014 is not used, the Wollaston prism 1015 may be set by rotating it about 45 degrees around the optical axis. At this time, the shape of the light receiving surface is shown in FIG.
You can do like this. FIG. 11C shows the shape of the light receiving surface of the photodetectors 1019a and 1019b (the light receiving surface is the shaded portion). Both photodetectors are arranged equidistantly before and after the focus of the lens 1017, and the track shift signal T
R (so-called diffracted light differential system) and defocus signal AF are obtained.

As described above, the wavelength of the light source is, for example, about 780 nm as the wavelength λ _{1 and about} 680 n as the wavelength λ _2.
If the former is used for recording information and the latter is used for error checking after recording, reproduction is performed at a wavelength shorter than the recording light, and the reproduction resolution is improved.

The signal obtained from the light of the wavelength λ ₁ constitutes the servo for the focus shift and the track shift. As a result, the track deviation of the recording spot can be accurately suppressed, and so-called data destruction due to the track deviation can be suppressed.

In order to check the error immediately after recording, it is necessary to position the recording spot and the reproduction (check) spot on the same track. To do this, the rotating mirror 1005 is rotated about the optical axis. Along with this rotation, the light beam moves on the photodetector, but since the track deviation signal is detected by the so-called three-spot method, an offset is unlikely to occur in the track deviation signal. This is effective when a so-called separation type optical system in which only the aperture lens 1009 moves is configured. The rotation mirror 1005 is rotated and controlled by using the track shift signal generated by the reproduction spot.

FIG. 13 shows another embodiment of the present invention. This is the configuration when the diffraction grating 1006 in FIG. 10 is not used. The components other than the photodetector 1016 are similar to those in FIG. FIG. 14A shows the light-receiving surface configuration of the photodetector 1016 in this embodiment.
When the diffraction grating 1006 is not used, track deviation is detected by the so-called diffracted light differential method. However, when the rotating mirror 1005 is moved to position the two narrowed spots on the same track, the light beam moves on the photodetector 1016. Therefore, there is a problem that an offset occurs in the track deviation detection signal. In order to solve this, in this embodiment, a part of the detector is subdivided. The same figure (b)
Shows one light receiving surface 1016a of the photodetector 1016. The light receiving surface is composed of Da, Db, and subdivided light receiving surface groups D1 to Dn. The light beam S is positioned substantially at the center of the light receiving surface, and the relationship between the diffracted light from the track and the light receiving surface is arranged as shown in the figure. At this time, as described above, an offset occurs in the diffracted light differential signal due to the movement of the rotating mirror 1005 or the displacement of the detector due to temperature change or vibration. Therefore, the signal DS from each light receiving surface
The position of the center of the light beam is detected by comparing a, DSb, and DS1 to DSn with the controller 1200, and the light receiving surface division position C for obtaining the diffracted light differential signal is determined. The dividing position of the light receiving surface is Dk and Dk + of the light receiving surface groups D1 to Dn.
When set to 1, as the diffracted light differential signals TRa and TRb, TRa = DSa + (DS1 + ... DSk) TRb = DSb + (DSk + 1 + ... DSn), and the track deviation detection signal TR is TR = TRa-TRb. can get. To determine the division position, for example, ISO
A so-called mirror portion, which is arranged between the address information and the data recording area in a standard disc or the like, is used.
In the above description, the case where the track deviation signal is detected from only one light receiving surface of the photodetector 1016 has been described, but the track deviation signal may be detected from both of the two light beams divided by the Wollaston prism 1016. It goes without saying that it is possible.

In the present invention, since the track guide groove is meandered in the track direction, when the light spot scans on the average center line of the meandered track guide groove,
The reflected light from the disc is intensity-modulated at a period that is twice the track meandering period. As described with reference to FIG. 2, the intensity of the reflected light from the disk becomes maximum when the light spot scans on the average center line of the track guide groove meandering.
Therefore, it is possible to perform tracking control by detecting only the intensity of reflected light from the disc. For example, in the configuration shown in FIG. 13, the tracking control of the light emitted from the laser light source 1001b can be performed by the method of detecting only the reflected light intensity.
A light spot control signal such as a focus shift and a track shift for positioning the squeezing lens 1009 at a predetermined position is detected by using a light spot from the laser light source 1001a and drives the squeezing lens 1009. As a result, the narrowed-down spot SPa in FIG. 11 is positioned at the center of the track. Further, since the spot SPb _{0 formed} by the light emitted from the laser light source 1001b is positioned on the same track as SPa, the light spot SPb is set as described above.
_The rotating mirror 100 so that the amount of reflected light from ₀ becomes maximum.
Rotate 5. In this case, the photodetector shown in FIG.
By forming one light-receiving surface (the one receiving the reflected light from the light spot SPb ₀ ) in (a) as a single light-receiving surface, the reflected light from the light spot SPb ₀ may be received in the total amount. With such a configuration, the rotating mirror 1005
Even if is rotated, offset does not occur in tracking unless the light beam deviates from the light receiving surface. Therefore, the adjustment range of the light spot SPb ₀ by the turning mirror 1005 is expanded, which is advantageous at the time of initial adjustment of the optical head. In order to perform a quick and reliable operation of positioning multiple light spots on the same track during initial adjustment of the optical head and during normal operation of the device, the meandering cycle of tracks is made different between adjacent tracks. You may stay. By detecting the frequency at which the reflected light intensity is modulated, the number of tracks in which a plurality of light spots are displaced can be known.

The present embodiment is premised on a magneto-optical disk (however, the magnet for applying an external magnetic field is omitted), and the photo-detector 1016 reproduces a magneto-optical signal. It is also possible to adopt a configuration in which the magneto-optical signal is reproduced by the detectors 1019a and 1019b. In that case, the beam splitter 1018
As a polarization beam splitter for separating p and s polarized light,
Set by rotating about 45 degrees around the incident optical axis, or set λ /
It is only necessary to rotate the polarization direction by about 45 degrees using two plates and make the light beam enter. Next, as the defocus signal detection method, for example, a so-called astigmatism method other than this embodiment can be used.

The method of the present invention may be applied to a phase change type optical disc, a write-once type optical disc, etc. other than the magneto-optical disc. In the case of a magneto-optical disk, wave plate 1008
Although the effect described in the description of FIG. 10 cannot be obtained without using, the system without using the wave plate 1008 can be realized if the output of the laser light source 1001a is sufficiently high. When a phase change type optical disc, a write-once type optical disc, or the like other than the magneto-optical disc is used, the wave plate 1008 has a quarter wavelength.
A wave plate may be used. 1 when using multiple wavelengths
The reference wavelength of the / 4 wave plate is set to an average value of a plurality of wavelengths or any light source wavelength.

Further, although various signals are detected by using the reflected light from the disk in this embodiment, the light transmitted through the disk may be used. In that case, the signal detection optical system 101
1 is a lens 100 that narrows down a disc 1010 and narrows it down.
It may be arranged so as to oppose to 9. In the present embodiment, the so-called diffracted light differential detection method has been mainly described for the track deviation signal detection method, but the essence of the present invention is not impaired even if the so-called sample servo method is used.

[0049]

According to the present invention, a wobbling track which is slightly displaced in the track scanning direction and the depth direction is used, and a pit edge recording method effective for improving the linear recording density in terms of optical resolution. Is used, and the reproduction pulse train from the leading edge and the pulse train from the trailing edge are processed by independent reproduction systems and then re-synthesized into the original data train, and Since the PLL response frequency that is high and is lower than the reproduction signal frequency is set, it is possible to follow the wobble fluctuation due to the wobble track in the PLL circuit. Therefore, in addition to the improvement of the track following characteristic and the focus following characteristic, the improvement of the recording and reproducing characteristic is achieved. By making the achievable minute displacement in the depth direction the opposite phase for each adjacent track, the track pitch is reduced by reducing the thermal interference between adjacent tracks. It can be reduced than that. Furthermore, the effect on the data pits that was a problem with the wobble method (such as fluctuations in edge position caused by the pit length being modulated by the wobble frequency) is higher than the wobble frequency in addition to the independent playback method for the front and rear edges. Since a PLL response frequency lower than the reproduction signal frequency is set and the wobble fluctuation due to the wobble track is tracked by the PLL circuit, it can be eliminated, so that it is possible to improve the light spot tracking characteristic and the recording density at the same time.

[Brief description of drawings]

FIG. 1 is an example of a basic configuration of an information recording / reproducing apparatus of the present invention.

FIG. 2 is a signal waveform of each part for explaining the track following operation in FIG.

FIG. 3 is a signal waveform example from a recording pit on a wobble track.

FIG. 4 is an example of a data reproducing circuit system.

FIG. 5 is a signal waveform of each part for explaining a reproduction pulse generation process.

FIG. 6 is an example of a sector format configuration of an optical disc.

FIG. 7 is an explanatory diagram of a relationship between a VFO sync pattern and a reproduction pulse.

FIG. 8 is an example of a basic configuration of a reproduction data synthesizing circuit.

9 is a time chart for explaining a reproduction data synthesizing process in FIG.

FIG. 10 is a diagram showing an optical head configuration of an optical disk device according to the present invention.

FIG. 11 is a diagram showing a state of narrowed spots on the disc.

FIG. 12 is a diagram showing the shape of the light receiving surface of the photodetector of the optical head according to the present invention.

FIG. 13 is a diagram showing another embodiment of the optical head configuration of the optical disk device according to the present invention.

FIG. 14 is a view showing the shape of a light receiving surface of a photodetector of an optical head according to another embodiment.

[Explanation of symbols]

1 ... Disc, 2 ... Light source, 6 ... Photodetector, 7 ... Adder,
8 ... Difference calculator, multiplier ... 11, edge detection circuit ... 19, 2
22 ... Reproduced data synthesizing circuit, 600, 601 ... VFO circuit, 1001a, 1001b ... Semiconductor laser light source, 10
02a, 1002b ... Collimating lens, 1003a,
1003b ... Beam shaping prism, 1004, 1012
... Wavelength filter, 1005 ... Rotating mirror, 1006 ... Diffraction grating, 1007 ... Beam splitter, 1008 ... Wavelength plate, 1009 ... Focusing lens, 1010 ... Disk,
1011 ... Detection optical system, 1013, 1017 ... Lens,
1014 ... λ / 2 plate, 1015 ... Wollaston prism, 1018 ... Polarizing beam splitter, 1016, 10
19a, 1019b ... Photodetector 1200 ... Controller.

Claims (17)

[Claims] 1. A recording medium provided with (wobble) track guide grooves displaced (meandering) in the track scanning direction, comprising:
By forming a recording area in a state different from the unrecorded area on the recording medium, the information is made to correspond to the leading edge portion and the trailing edge portion of the recording area, and the leading edge has a predetermined order relationship in the specific area. And the trailing edge are positioned so that the edge information of the leading edge and the trailing edge of the recording area are independently detected during reproduction, and the edge information is stored in the storage means, and then the specific area is stored. An information recording / reproducing method characterized in that the information is reconstructed based on the order relation of. 2. The information recording method according to claim 1, wherein the information recording medium is an optical disk medium. 3. The information recording / reproducing method according to claim 2, wherein a plurality of light spots are arranged on the optical disk medium to record and reproduce the information. 4. Two light spots are arranged on the same track on the optical disk medium, information is recorded by a preceding light spot, and the recorded information is reproduced by a following light spot. The information recording / reproducing method according to claim 2. 5. The information recording / reproducing method according to claim 1, wherein the displacement frequency of the track guide groove in the track scanning direction is set higher than the control band of the light spot position control. 6. The information recording / reproducing method according to claim 1, wherein a displacement frequency of the track guide groove in the track scanning direction is set lower than a reproduction signal frequency of recording data. 7. A recording medium having a track guide groove displaced (meandering) at a predetermined frequency in the track scanning direction, wherein a recording area in a state physically different from an unrecorded portion is formed on the recording medium. In an information recording / reproducing apparatus for recording information and reproducing the information, a light source, a means for irradiating a recording medium with a light beam emitted from the light source, and the information for recording the information in the recording area by the light beam. Means for recording corresponding to the leading edge portion and the trailing edge portion, and recording so that the leading edge portion and the trailing edge portion are positioned in a predetermined order in a specific area, and reflected light of the recording medium or A means for independently detecting a leading edge portion and a trailing edge portion of the recording area from the transmitted light to store the respective edge information, and means for reconstructing the edge information based on the order relation of the specific area, From the reflected light or the transmitted light, A shift amount detection means for detecting a deviation, the information recording and reproducing apparatus characterized in that it comprises a means for correcting the track deviation from the deviation amount detected by said deviation detection means. 8. The information recording / reproducing apparatus according to claim 7, wherein the information recording medium is an optical disk medium. 9. The information recording / reproducing apparatus according to claim 7, wherein the light beam is applied to the information recording medium as a plurality of light spots. 10. The information processing apparatus according to claim 7, wherein the light beams are a plurality of light beams having different wavelengths, and the information recording medium is irradiated with the light beams. 11. The plurality of light beams are arranged on the same track, and information is recorded by the preceding light beams,
11. The information recording / reproducing apparatus according to claim 9, wherein the recorded information is reproduced by a subsequent light beam. 12. The information processing apparatus according to claim 7, wherein the frequency is set higher than a control band for light spot position control. 13. The information processing apparatus according to claim 7, wherein the frequency is set lower than the reproduction signal frequency of the recorded data. 14. A reproduction clock generation means of two series which are respectively independently synchronized with the edge information is provided, and the reproduction clocks of two series generated by the reproduction clock generation means are used, and each of the reproduction clocks is used. When the independently synchronized reproduction pulses are stored in the storage means, the relationship between the intervals and the order of the reproduction pulse trains obtained from the front edge portion and the rear edge portion of the specific pattern portion previously recorded in the specific area at the time of recording information is normalized. Means for controlling the storage location of the storage means to store the reproduction pulse so as to have the same order relation as the interval of, and either the reproduction clock or the reproduction clock when reading the reproduction data from the storage means. 14. The information processing apparatus according to claim 7, further comprising a reproduction clock generation unit that uses a clock other than the reproduction clock. 15. The reproduction clock generation means has at least means for detecting a phase difference between the reproduction pulse and the reproduction clock and correcting the phase difference, and the phase correction tracking operation band of the reproduction clock generation means is an optical spot. 15. The information processing apparatus according to claim 14, wherein the information processing apparatus is set to a position above a control band for position control, above a track displacement (wobble) frequency, and below a band of information bits or information reproduction signals. 16. A recording medium having a track guide groove displaced (meandering) at a predetermined frequency in the track scanning direction has a displacement frequency of the guide groove in the scanning direction which is the position of a light spot irradiated on the recording medium. An information recording medium characterized by being higher than the control band. 17. A recording medium having a track guide groove displaced (meandering) at a predetermined frequency in the track scanning direction has a displacement frequency of the guide groove in the scanning direction, reproduction of recorded data recorded on the recording medium. An information recording medium characterized by being lower than the signal frequency.