JP3333743B2 - Address information allocation method, recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording / reproducing apparatus, and more particularly to a high-density optical recording medium having a track width smaller than a light spot and an optical recording / reproducing apparatus.

[0002]

2. Description of the Related Art FIG. 5 shows a configuration example of a conventional magneto-optical recording / reproducing apparatus. Laser light emitted from a laser 311 mounted on the optical head 3 is collimated into parallel light by a collimating lens 312, passes through a beam splitter 324,
Further, the light spot 21 is formed on the magneto-optical recording medium 8 by being condensed by the lens 321. The position of the light spot 21 on the magneto-optical recording medium 8 is controlled by moving the lens 321 and the optical head 3 by the light spot scanning control means 63. The reflected light from the magneto-optical recording medium 8 is guided to the light detecting means 33 by the beam splitter 324. The reproduction signal from the light detection means 33 is processed by the reproduction circuit 93 and is converted into reproduction data. The overall control of the reproduction is performed by the controller 55. This method is disclosed, for example, in JP-A-59-191156.

A conventional example of a medium for performing high-density (narrow track) recording is disclosed in, for example,
176404. In this example, in an optical recording medium having a groove portion and an inter-groove portion on a substrate as a recording medium and having an information recording area in both the groove portion and the inter-groove portion, a virtual extension of a boundary portion between the groove portions and the inter-groove portion is provided. Pre-pits are placed on the line. The pre-pits are arranged so as to exist only on one side of the same location in the groove. Thereby, the recording information is recorded in both the groove portion and the groove portion, and the address information indicating the recording area is assigned to the pre-pit, and the address information for the pair of groove portion and the groove portion is recorded by one pre-pit. We share. When this method is applied to, for example, a phase-change type recording medium or a magneto-optical recording medium, in the groove portion and the inter-groove portion, the information of the adjacent inter-groove portion or the groove portion is not mixed due to the interference effect in the light spot ( Since crosstalk is eliminated), it is possible to narrow the track. On the other hand, in the pre-pit portion, since this interference effect is not provided, address information for a pair of groove portions and an inter-groove portion is shared, an effective track pitch is increased, and crosstalk is reduced.

[0004]

However, in the above-mentioned conventional example, the pre-pit portion is arranged on one side of the groove portion or the inter-groove portion, so that the light spot follows the groove portion or the inter-groove portion. At this time, the tracking deviation (track offset) becomes large, and as a result, it is difficult to perform high-density recording with a narrow track pitch.

A first object of the present invention is to solve the above-mentioned problems and to keep track offset sufficiently low for practical use even when recording is performed in both a groove portion and an inter-groove portion, and to efficiently address information. An object of the present invention is to provide an optical recording medium that can be arranged. A second object of the present invention is to solve the above-mentioned problem and to reduce the track offset sufficiently low for practical use and to obtain address information even when recording is performed in both the groove and the groove. An object of the present invention is to provide a recording and reproducing device.

[0006]

In order to achieve the first object, the following means are used. (1) having a groove portion and an inter-groove portion on a substrate, having an information recording area in both the groove portion and the inter-groove portion, arranging prepits on a virtual extension line at a boundary between the groove portion and the inter-groove portion, The prepits are located on both the left and right sides of the virtual extension line of the groove center line, and the prepits are located on both the left and right sides of the virtual extension line of the inter-groove center line, and on both sides of the same location of the groove. Used an optical recording medium in which no pre-pits were present at the same time, and no pre-pits were simultaneously present on both sides of the same location between the grooves.

As a result, the prepits are not disposed on one side of the left or right with respect to the virtual extension line of the center line of the groove or the inter-groove portion. Since there is no pre-pit on both sides of the same location at the same time, the pre-pit information of the adjacent track does not mix in the reproduction spot, thereby enabling high-density narrow-track recording.

(2) The pre-pits are arranged alternately on the left and right with respect to an imaginary extension of the groove center line at a cycle of an even multiple of the information recording unit. As a result, the pre-pits are evenly arranged on both sides with respect to the virtual extension line of the groove or the center line between the grooves, so that a track offset is less likely to occur.

(3) The groove depth of the groove is the same as the depth of the prepit, and the depth is 70 nm or less.
More preferably, the depth is 40 nm or more and 60 nm or less. Thereby, an appropriate crosstalk canceling effect can be obtained in the groove portion and the inter-groove portion, and a good tracking servo signal can be obtained. The molding and production of the medium becomes easy. Here, if the groove depth exceeds 70 nm, it becomes difficult to form the groove. Further, when the groove depth is about 50 nm, the tracking servo is maximized, and almost the same effect can be obtained when the groove depth is about 10 nm.

(4) The width of the groove and the space between the grooves is substantially the same and is between 0.3 μm and 0.75 μm. This allows
It is possible to achieve both good tracking and high-density recording.
This is because if the width of the groove and the space between the grooves is less than 0.3 μm, two pairs of the groove and the space between the grooves enter into one light spot at the same time, and a good tracking signal cannot be obtained. On the other hand, if the width of the groove and the space between the grooves exceeds 0.75 μm, effective high-density recording cannot be performed.

(5) The diameter of the smallest one of the prepits is smaller than the width of the groove and the space between the grooves. More preferably, the diameter is from 0.25 μm to 0.55 μm
In the range. Thereby, a good pre-pit signal can be obtained without crosstalk. Because the diameter 0.2
If it is less than 5 μm, the pre-pit signal extremely decreases, and if it exceeds 0.55 μm, crosstalk occurs.

In order to achieve the second object, the following means are used. (1) Using the above optical recording medium, light generating means, light condensing means for condensing and irradiating light emitted from the light generating means onto the optical recording medium, and light irradiating by the light condensing means A light detecting means for detecting reflected light of the light, a reproducing means for reproducing information by using a signal from the light detecting means, and a position of a light spot radiated by the light condensing means to any position on the optical recording medium. At least scanning means for moving to a position, means for detecting an address based on a reproduction signal from the pre-pit, means for detecting an amplitude of a reproduction signal from the pre-pit, means for storing the amplitude, An optical recording / reproducing apparatus having at least means for comparing amplitudes and having a function of controlling the position of a light spot based on the comparison amplitude was used. This makes it possible to keep track offset low enough for practical use and to obtain address information.

(2) Using the above optical recording medium, light generating means, light condensing means for condensing and irradiating the light emitted from the light generating means onto the optical recording medium, and irradiating with the light condensing means Light detecting means for detecting reflected light of the reflected light, reproducing means for reproducing information using a signal from the light detecting means, and a position of a light spot irradiated by the light condensing means on the optical recording medium. Means for detecting an address based on a reproduction signal from the pre-pit, and a low-pass transmission filter for transmitting a low-frequency component of the reproduction signal from the pre-pit. An optical recording / reproducing apparatus having at least means for synchronously detecting a transmission signal of the low-pass filter and having a function of controlling the position of a light spot based on the detection signal. This makes it possible to further reduce the track offset.

[0014]

According to the present invention, for example, as shown in FIG. 1, prepits are arranged on both sides of a virtual extension line of the groove or the center line between the grooves. For this reason, the bias is reduced and the track offset is less likely to occur, and the prepits do not exist on both sides of the same portion of the groove or the inter-groove at the same time, so that the prepit information of the adjacent track does not mix in the reproduction spot. Thus, high-density narrow track recording becomes possible.

Further, even if a track offset occurs as shown in FIG. 2, the track offset amount can be accurately detected by comparing the signal amplitudes of the left and right pre-pits. Therefore, the track offset can be suppressed by feedback-controlling this information to the scanning unit.

[0016]

Embodiment << Embodiment 1 >> (Optical Recording Medium) FIG. 1 is an enlarged partial plan view of an optical recording medium of the present invention. Grooves (grooves 84) having a width of 0.6 μm and depth of 50 nm and inter-grooves (lands 85) having a width of 0.6 μm are alternately arranged, and the recording marks 81 are recorded in both regions. That is, both the land 84 and the groove 85 are recording areas. No groove is formed in the pre-pit portion 83, and the pit 82 is arranged on an extension of the boundary between the land portion and the groove portion. Pit width is 0.35μ
m, the depth is 50 nm. The pre-pit section is divided into a first pre-pit section 831 and a second pre-pit section 832. Pit 8 in the first pre-pit section 831
Numeral 2 is arranged above the center line of the land 85 in the figure, and in the second pre-pit section 832, the pit 82 is arranged below the center line of the land 85 in the figure. Therefore, for example, when the light spot 21 scans over the land 85, only one of the pits is always reproduced, and there is no fear that crosstalk from an adjacent track will occur. Therefore, it is possible to satisfactorily reproduce the address information allocated to the pre-pits without crosstalk. Further, since the pits 82 are not adjacent to each other, the molding becomes easy. Tracks (land or groove)
Since the pits 82 are evenly arranged on both sides of the tracking servo signal, the effect of the pits 82 on the tracking servo signal is offset. Therefore, the track offset can be kept sufficiently small. Further, for example, when the land portion 85 is reproduced, the first pre-pit portion 831 and the second
The address information of the pre-pit section 832 is continuously reproduced. Therefore, by arranging information so that address information is obtained by combining the two, addresses (track numbers) can be set independently for both the land portion and the groove portion. Here, a magneto-optical recording film (TbFeCo) was used as the recording film. Therefore, the recording marks are formed in the form of recording magnetic domains.

Embodiment 2 (Optical Recording Medium) FIG. 6 is an enlarged partial plan view of the optical recording medium of the present invention. Grooves (grooves 84) having a width of 0.5 μm and a depth of 40 nm and inter-grooves (lands 85) having a width of 0.5 μm are alternately arranged, and recording marks 81 are recorded in both regions. That is, both the land 84 and the groove 85 are recording areas. No groove is formed in the pre-pit portion 83, and a substantially circular pit 82 (having a diameter of 0.3 μm and a depth of 40 nm) is arranged on an extension of the boundary between the land portion and the groove portion. The pre-pit portion is a VFO portion 83
3 and an address section 834. In particular, in the VFO section, the pits 82 are arranged so as to be alternately up and down with respect to the center line of the land 85. In the address section, the pits 82 are arranged so as to alternate with the same cycle as the VFO section. Therefore, there are no pits on both sides of the same location of the land or groove at the same time. Further, in the address portion, encoding is performed so that there is only one pit difference from data adjacent to one track. That is,
Gray code. Therefore, for example, when the light spot 21 scans over the land 85, only one of the pits is always reproduced, and there is no fear that crosstalk from an adjacent track will occur. Therefore, it is possible to satisfactorily reproduce the address information allocated to the pre-pits without crosstalk. Further, since the pits 82 are not adjacent to each other, the molding becomes easy. Further, since the pits 82 are evenly arranged on both sides of the track (land portion or groove portion), the effect of the pits 82 on the tracking servo signal cancels out. Therefore, the track offset can be kept sufficiently small.

FIG. 7 shows a reproduced signal of the pre-pit section 83 of this embodiment. That is, different data can be obtained for each track, so that the address information is recorded very efficiently. Further, since the gray code is used, the address can be reproduced even during the inter-track access, which is suitable for high-speed access. Further, since a gray code is used, errors are unlikely to occur even if there is crosstalk, which is suitable for narrowing the track.

Embodiment 3 (Optical Recording / Reproducing Apparatus) FIG. 3 shows an example of the configuration of an optical recording / reproducing apparatus of the present invention, and FIG. 4 shows an example of a portion of the apparatus exhibiting the features of the present invention in more detail. I do. In this embodiment, a semiconductor laser 311 having a wavelength of 680 nm and a collimating lens 312 are used as the light generating means 31. If necessary, a beam shaping means such as a prism may be provided. The intensity of the semiconductor laser is controlled by a light intensity control means 71 having an automatic light intensity control function. The light 22 emitted from the light generating means 31 is focused on the magneto-optical recording medium 8 by the focusing means 32. The light collecting means 32 includes at least one lens 321. In this example, a beam splitter 324 is additionally provided. The aperture ratio of the objective lens 321 focused on the optical recording medium 8 was set to 0.55. Therefore, the diameter of the light spot 21 on the magneto-optical recording medium 8 is 1.1 μm. The light spot can be moved to any position on the optical recording medium 8 by the scanning means 6. In this embodiment, the scanning means 6
Motor 62 for rotating disk-shaped magneto-optical recording medium 8
And at least automatic position control means 61 having functions of automatic focus control and automatic tracking. The automatic position control means 61 performs feedback control by detecting the light spot position with the servo signal detector 34 using the reflected light 23 from the magneto-optical recording medium 8. The light spot position is detected by detecting the intensity of the diffracted light from the groove. In this example, the reflected light from the light spot 21 is reflected by the beam splitters 324 and 35 provided in the focusing unit 32.
Accordingly, the light is guided to the light detection means 33 and the servo signal detector 34. As the light detecting means 33, a half-wave plate 33
7, lens 331, polarizing beam splitter 332,
It consists of detectors 333 and 334. The reproduced signal converted into an electric signal by the light detecting means is converted into a magneto-optical signal by the differential amplifier 944, and is converted into a pre-pit signal by the adder 941.

In the present invention, the optical recording medium according to the first embodiment is used.
Was used. Therefore, a signal 14 as shown in FIG. 2 is obtained as the pre-pit signal. By inputting this signal to the address detection means 43, the address information is demodulated by the address demodulation means 431, and at the same time, the timing of the signals of the first pre-pit part and the second pre-pit part is generated by the time control means 432. . Based on this timing information, the first amplitude detection and storage means 411 stores the amplitude (average maximum amplitude) of the first pre-pit section, and the second amplitude detection and storage means 412 stores the amplitude (average maximum) of the second pre-pit section. (Maximum amplitude). Here, the first amplitude detection and storage unit 411 and the second amplitude detection and storage unit 412 can share an amplitude detection portion. The stored amplitudes are compared by the amplitude comparing unit 42, added as track offset information to the error signal from the servo signal detector 34, and fed back to the position moving unit (scanning unit). Here, FIG. 2 shows the pre-pit signal 14 when the light spot is located on the groove (on the groove) and on the land (between the grooves) and the magneto-optical reproduction signals 11 and 12 on the groove and on the land. is there. In this example, since the light spots are slightly offset as shown in FIG. 1, the amplitude difference between the pre-pit signals from the first pre-pit section 831 and the second pre-pit section 832 is one.
3 has occurred. This amplitude difference 13 corresponds to the amount of track offset.

By using the apparatus of this embodiment, the track offset can be reduced to ± 0.03 μm or less even when various disturbances such as aberration of the light spot are taken into consideration. In a nominal state having no spot aberration or the like, the value was ± 0.015 μm or less. When recording is performed by the apparatus of this embodiment, the recording light 22, the intensity of which is controlled by the light intensity control means 71, is irradiated onto the magneto-optical recording medium 8 to form the light spot 21. In the vicinity of the light spot, the bias magnetic field intensity control means 72 and the bias magnetic field applying circuit 7
3, while applying a bias magnetic field by the bias coil 74, the temperature of the medium 8 is heated to near the Curie temperature by the light spot 21 to form a recording magnetic domain (not shown) in that area. In this example, the size of the recording magnetic domain 41 is aimed at a width of about 0.5 μm. In this example, a magneto-optical recording medium 8 having a TbFeCo-based recording film was used.

Embodiment 4 (Optical Recording / Reproducing Apparatus) FIG. 8 shows a configuration example of an optical recording / reproducing apparatus according to the present invention. The difference from the third embodiment is that, in order to generate the track error information from the pre-pit signal, the synchronization is detected by the synchronization detecting means 44 through the low-pass filter 45. In this example, since the optical recording field plate of the second embodiment is used, the pits 82 are alternately arranged on the left and right of the land 85 or the groove 84 in the VFO 833. Accordingly, as shown in FIG. 9, the low-pass filtering component 16 of the VFO signal 15 when there is no offset has no amplitude, but when there is a track offset, the low-pass filtering component 18 of the VFO signal 17 has an amplitude. Have. The track offset can be detected by synchronously detecting the amplitude. Therefore, the track offset can be reduced by feedback-controlling the offset amount to the scanning means 6. In this embodiment, the track offset could be suppressed to ± 0.025 μm or less.

The effect of the present invention is not limited to the above embodiment. For example, an optical head having a function of simultaneously generating a plurality of light spots may be used.
As a medium, a phase change recording medium may be used in addition to a magneto-optical recording medium. As a servo signal detection method, a three-spot method or a wobble method for comparing the intensities of the reflected light from a plurality of light spots may be used in addition to the method using the diffracted light.

[0024]

By using the optical recording medium of the present invention, the track offset can be reduced to a level (0.0
(3 μm or less), and address information can be easily obtained even during high-density narrow-track recording. By using the optical recording / reproducing apparatus of the present invention, track offset can be easily reduced by feedback control.

[Brief description of the drawings]

FIG. 1 is an enlarged partial plan view of an embodiment of the optical recording medium of the present invention.

FIG. 2 illustrates the principle of the present invention.

FIG. 3 is a configuration diagram of an embodiment of an optical recording / reproducing apparatus of the present invention.

FIG. 4 is a partial configuration diagram of an embodiment of an optical recording / reproducing apparatus according to the present invention.

FIG. 5 is a configuration diagram of a conventional optical recording device.

FIG. 6 is an enlarged partial plan view of an embodiment of the optical recording medium of the present invention.

FIG. 7 shows an example of a reproduced signal obtained from the optical recording medium of the present invention.

FIG. 8 is a partial configuration diagram of an embodiment of the optical recording apparatus of the present invention.

FIG. 9 is a diagram illustrating the principle of an optical recording apparatus according to the present invention.

[Explanation of symbols]

3 optical head, 5 main control means, 6 scanning means, 8 magneto-optical recording medium, 11 reproduction signal of groove, 12 reproduction signal of land, 13 first and second pre-pits and second Amplitude difference of the pre-pit portion, 14... Reproduced signal of the pre-pit portion, 15, 17... VFO signal, 16, 18... Low-frequency component, 21 .light spot, 22 .laser light, 23... Reflected light, 31. .. 32 light collecting means, 33 light detecting means, 34 servo signal detecting means, 35 beam splitter, 41 amplitude detecting storage means, 42 amplitude comparing means,
43 ... address detecting means, 44 ... sync detecting means, 45 ...
Low-pass filter, 51 central control means, 56 recording / reproduction control means, 61 automatic position control means, 62 motor,
71: light intensity control means, 72: bias magnetic field intensity control means, 73: bias magnetic field application circuit, 74: bias magnetic field application means, 75: modulation magnetic field application circuit, 76: magnetic head, 81: recording mark, 82: prepit, 83 pre-pit section, 831 first pre-pit section, 832 second
833 VFO section, 834 address section, 84 groove section, 85 land section, 91 reproducing means, 92 demodulation circuit, 941, 942 adder, 94
3, 944: Differential amplifier.

──────────────────────────────────────────────────の Continuing from the front page Judge of the Joint Panel Jiro NAITO Judge Kiyoshi TARASHIMA Judge Kouichi Asano (56) References JP-A-6-96447 (JP, A) Patent 2878022 (JP, B2) (58) Investigation Field (Int.Cl. ⁷ , DB name) G11B 7/24

Claims (2)

(57) [Claims] A first address information of a plurality of marks arranged on a virtual extension line of a boundary between the inter-groove portion and a groove portion adjacent to one side of the inter-groove portion, wherein the first inter-groove portion and the inter-groove portion are arranged; The second address information of a plurality of marks is arranged on an imaginary extension line of the boundary with the groove adjacent to the other side, and the first address information is stored in the inter-groove portion and one of the inter-groove portions.
The second address information is shared by the adjacent groove portions, and the second address information is shared by the inter-groove portions and the other inter-groove portions.
, And the first address information and the second address information are not simultaneously located on both sides with respect to the center line of the inter-groove portion. A method for allocating address information to a recording medium having a plurality of recording tracks, wherein a unique address to the portion of the inter-groove portion is provided from the first and second address information. 2. The method according to claim 1, wherein each of the first and second address information is represented by a plurality of pits.
Address information allocation method described in.