JP4112124B2 - Optical recording medium, recording / reproducing apparatus and recording / reproducing method for recording / reproducing information on / from the optical recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to information recording / reproduction with respect to an optical recording medium, and more particularly, to information recording / reproduction with respect to an optical recording medium having a plurality of recording surfaces and guide portions.
[0002]
[Prior art]
In recording / reproducing information on / from an optical recording medium such as a magneto-optical disk drive, write-once disk drive, phase change disk drive, CD-ROM, DVD, optical card, etc., a plurality of recording surfaces are formed in one recording layer, It has hitherto been proposed to record and reproduce information for each of them. As used herein, the term “recording / reproducing” means recording and / or reproducing information. That is, it refers to performing either recording or reproduction of information at a time.
[0003]
Japanese Laid-Open Patent Publication No. 4-301226 discloses an optical recording medium on which a plurality of recording surfaces can be formed, and a recording / reproducing apparatus for recording / reproducing information on such an optical recording medium.
[0004]
The optical recording medium has a guide surface on which tracks are formed and a single recording layer having a thickness capable of forming a plurality of recording surfaces. The recording / reproducing apparatus includes a recording / reproducing optical system for forming a recording / reproducing spot for recording / reproducing information on a recording surface, and a guide optical system for forming a guide spot to follow the track on the guide surface. Have.
[0005]
The position of the recording / reproducing spot with respect to the guide spot in the thickness direction of the recording layer is determined by an optical axis direction shifter controlled by an adjusting member that outputs a plurality of discrete signals corresponding to the position of the recording surface in the optical axis direction. It has been decided.
[0006]
[Problems to be solved by the invention]
In such a recording / reproducing apparatus, since the recording surface itself does not have a reflecting surface or a track that serves as a guide in the optical axis direction or the tracking direction, the position of the recording / reproducing spot is relative to the guide spot arranged on the track on the guide surface. Must be controlled relatively accurately.
[0007]
As described above, the position of the recording layer in the thickness direction of the recording / reproducing spot is determined by the optical axis direction shifter controlled by the adjusting member that outputs a plurality of discrete signals. For this reason, a plurality of discrete signals output from the adjusting member fluctuate due to temperature changes, changes with time, etc., the output sensitivity of the optical axis direction shifter changes, the recording / reproducing optical system and the guide When the optical path length of the optical system changes relatively, the position of the recording / reproducing spot in the optical axis direction with respect to the guide spot deviates from a certain value.
[0008]
For this reason, for example, when the recording / reproducing spot shifts in the optical axis direction described above during recording, the recording state changes, and a recording surface partially shifted in the optical axis direction is formed. When reproducing such a recording surface, even if focus control is performed at the focal point of the recording surface, the focus error and tracking error increase at the shifted portion, and reproduction cannot be performed correctly.
[0009]
The present invention has been made to solve such problems, and its purpose is to stably record information on a plurality of recording surfaces that can be formed in one recording layer of an optical recording medium. It is to provide a technique for performing reproduction. More specifically, it is to provide an optical recording medium, a recording / reproducing apparatus, and a recording / reproducing method for enabling such stable information recording / reproducing.
[0010]
[Means for Solving the Problems]
In one aspect, the present invention is an optical recording medium on which a plurality of recording surfaces can be formed, and includes a base layer and a recording layer provided thereon, and the recording layer includes a plurality of recording layers. The recording surface can be formed, and the base layer is formed with a guide surface on which the track is formed and at least one reference value for a distance between the recording surfaces formed in the recording layer formed at a height different from the guide surface. And a reference plane.
[0011]
According to another aspect of the present invention, there is provided a recording / reproducing apparatus for recording / reproducing information with respect to the optical recording medium, wherein the first optical system for forming a guide spot and the recording / reproducing spot are formed. A second optical system, means for holding the guide spot on the guide surface, means for changing the height of the recording / reproducing spot with respect to the guide spot, and the recording / reproducing spot and the reference surface located on the guide surface The height of the reference surface relative to the guide surface is obtained from the difference in height of the recording / reproducing spot located at the position, and based on this, a means for obtaining a reference value of the interval between the recording surfaces is obtained. Based on the reference value, the recording / reproducing spot is arranged at a desired height that is an integral multiple of the reference value with respect to the guide spot, and recording / reproduction is performed with the recording / reproducing spot while the guide spot is held on the guide surface.
[0012]
According to another aspect of the present invention, there is provided a method for recording / reproducing information with respect to the optical recording medium described above, the step of arranging the spot for recording and the spot for recording / reproduction on the guide surface, and the spot for recording / reproduction as a reference plane. The step of arranging, the step of obtaining the reference surface height with respect to the guide surface based on the height change of the recording / reproducing spot, and obtaining the reference value of the interval of the recording surface based on this, and the obtained reference value And a step of arranging the recording / reproducing spot at a desired height that is an integral multiple of the reference value from the guide surface, and a step of recording / reproducing with the recording / reproducing spot while holding the guide spot on the guide surface; have.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
[First Embodiment]
As shown in FIG. 1, the light emitted from the recording / reproducing LD 11 is linearly polarized light perpendicular to the paper surface and is collimated by the collimating lens 12. The collimating lens 12 is appropriately moved along the optical axis by the support driving means 13, and the position in the optical axis direction is detected by the sensor 14. The support driving means 13 is constituted by, for example, two parallel springs that support the collimating lens 12 so as to be movable in the optical axis direction, and a driving device including a coil and a magnet.
[0015]
The light collimated by the collimating lens 12 enters a beam splitter (half mirror) 15, a part of which is transmitted therethrough, and the rest is reflected thereby. The light transmitted through the beam splitter 15 is collected by the condenser lens 16 and enters the monitor PD 17. The monitor PD17 is used for measuring the amount of light emitted from the LD11.
[0016]
The light reflected by the beam splitter 15 is reflected by the PBS 18 and travels to the mirror 19. Subsequently, as shown in FIG. 2, the light is reflected by the mirror 19 and condensed by the objective lens 20 to form a spot P 1 in the recording layer 3 of the disk 1.
[0017]
The reflected light from the spot P1 travels back along the optical path at the time of incidence and reaches the beam splitter 15, and as shown in FIG. And is incident on the PD 22. The PD 22 has a light receiving surface divided into four parts, and is used for detection of a focus error signal and a recording / reproducing signal related to the recording / reproducing spot P1 based on the astigmatism method.
[0018]
On the other hand, as shown in FIG. 2, the light emitted from the guide LD 30 is linearly polarized light parallel to the paper surface, passes through the hologram 31, is collimated by the collimating lens 32, passes through the PBS 18, and is reflected by the reflection mirror. The light is reflected by 19 and collected by the objective objective lens 20 to form a spot P 2 on the guide surface 5 of the disk 1.
[0019]
The optical axis 33 of the guide optical system has an inclination θ with respect to the optical axis 34 of the recording / reproducing optical system. Therefore, the guide spot P2 is formed at a position away from the recording / reproducing spot P1 by a predetermined distance a in the tracking direction (perpendicular to the recording track). The distance a is selected from 5 μm to 100 μm.
[0020]
As shown in FIG. 1, the reflected light from the spot P2 is diffracted by the hologram 31 along the optical path at the time of incidence. The ± first-order light is incident on PDs 35a and 35b each having a light receiving surface divided into six parts. Both ± primary lights are convergent lights, one focal point is located in front of PD 35a, and the other focal point is located behind PD 35b. The PDs 35a and 35b are used for detecting a focus error signal by a so-called beam size method and for detecting a tracking error signal and a reproduction signal (track number) by a push-pull method with respect to the guide focal point P2.
[0021]
As shown in FIG. 2, the recording / reproducing apparatus has a support driving means 40 for moving the objective lens 20, and the objective lens 20 is moved in two directions of the focus direction and the tracking direction by the support driving means 40. Moved as appropriate.
[0022]
As can be seen from the above description, the light from the recording / reproducing LD 11 and the light from the guiding LD 30 have orthogonal polarization directions and are combined and separated by the PBS 18. Both the light and the light from the LD 11 incident on the PDs 35a and 35b are very small.
[0023]
Further, since the optical axis 33 of the guide optical system is inclined with respect to the optical axis 34 of the recording / reproducing optical system, the light from the LD 11 and the light from the LD 30 are separated in the direction perpendicular to the paper surface of FIG. The light from the LD 11 does not enter the light receiving surfaces of the PDs 35 a and 35 b, and the light from the LD 30 does not enter the light receiving surface of the PD 22. As a result, a good signal with less crosstalk and noise between PDs can be obtained.
[0024]
As shown in FIG. 3, the disk 1 has a base layer 2 and a recording layer 3 laminated thereon. The base layer 2 has a guide surface 5 and three reference surfaces 7a, 7b, 7c. The guide surface 5 has a track 6 having a high reflectivity.
[0025]
The three reference surfaces 7 a, 7 b, 7 c are located on the inner peripheral side of the disk 1 and are located at a distance d from the guide surface 5. That is, the reference surfaces 7a, 7b, and 7c are located at heights d, 2d, and 3d from the guide surface 5, respectively. The distance d is preferably 2 to 50 μm, more preferably 5 to 15 μm.
[0026]
At least one recording surface is formed in the recording layer 3 at a distance from the guide surface 5. For example, the three recording surfaces 4a, 4b, and 4c are formed at the same height as the reference surfaces 7a, 7b, and 7c, respectively.
[0027]
The recording / reproducing operation for the recording surface 4a will be described below. First, in accordance with the focus error signal obtained based on the PDs 35a and 35b, the objective lens 20 is moved by the support driving means 40, and the spot P2 is arranged on the track 6 of the guide surface 5. Subsequently, the collimating lens 12 is moved by the support driving means 13 in accordance with the focus error signal obtained based on the PD 22, and the spot P <b> 1 is disposed on the guide surface 5.
[0028]
Next, the track number of the track 6 where the spot P2 is located is read based on the outputs of the PDs 35a and 35b, the objective lens 20 is moved to the inner peripheral side according to the read track number, and the objective lens 20 is drawn with an imaginary line. As described above, the optical axis of the recording / reproducing optical system crosses the reference plane 7a, and the spot P2 of the guiding optical system is disposed at a position where the track 6 is captured.
[0029]
Subsequently, the collimating lens 12 is moved so that the focus error signal obtained based on the PD 22 becomes zero, and the recording / reproducing spot P1 is arranged on the reference plane 7a. Thereafter, the position of the collimating lens 12 is controlled by the support driving means 13 so as to keep the output of the sensor 14 constant. By this control, the position of the spot P2 in the focus direction with respect to the spot P1 is kept constant.
[0030]
The position control of the collimating lens 12 may be performed so as to keep the driving current flowing through the coil of the support driving means 13 constant. However, such control is more effective than the control based on the sensor 14 such as external vibration. The position accuracy in the focus direction of the spot P2 with respect to the spot P1 is low.
[0031]
Thereafter, the objective lens 20 is moved in the tracking direction, and the spot P2 is arranged on the desired track 6. In this way, the position P in the tracking direction is controlled with respect to the spot P2 of the guide optical system with reference to the track 6 on the guide surface 5, so that the position P1 of the optical system for recording and reproduction is indirectly controlled in the tracking direction. Is done.
[0032]
The position of the objective lens 20 is controlled in the focus direction in accordance with a focus error signal obtained based on the PDs 35a and 35b, whereby the spot P2 is kept focused on the track 6 on the guide surface 5. In other words, the guide spot P2 is always maintained on the guide surface 5.
[0033]
As described above, the position of the collimating lens 12 is controlled so as to keep the output of the sensor 14 constant, so that the position of the spot P2 in the focus direction with respect to the spot P1 is kept constant, that is, the distance d. Accordingly, the spot P2 is always located on a surface separated from the guide surface 5 by a certain distance d.
[0034]
This means that the recording surface 4a that is accurately spaced from the guide surface 5 by the distance d is formed during recording, and the spot P1 is always correctly positioned on the recording surface 4a during reproduction. Therefore, stable recording and reproduction can be performed.
[0035]
Recording and reproduction with respect to the recording surface 4b can be performed in the same manner. That is, first, the objective lens 20 is arranged at a position where the optical axis 34 of the recording / reproducing optical system crosses the reference surface 7b and the spot P2 of the guiding optical system catches the track 6 of the guide surface 5. Subsequently, after the spot P1 is aligned with the reference plane 7b, the position of the spot P1 in the focus direction with respect to the spot P2 is maintained by keeping the output of the sensor 14 constant. Thereafter, the spot P2 is controlled in the focus direction with respect to the track 6 on the guide surface 5. As a result, the spot P1 is maintained on the recording surface 4b separated from the guide surface 5 by a certain distance d. The same applies to recording / reproduction with respect to the recording surface 4c.
[0036]
As can be seen from the above description, the relative positions of the spot P1 and the spot P2 in the focus direction have conventionally been changed, such as fluctuations in the wavelengths of the LD11 and LD30, changes in the drive current sensitivity of the support drive means 13, and offsets of the sensor 14. The relative positions of the spots P1 and P2 can be accurately and stably maintained against various factors that shift.
[0037]
In this embodiment, the number of recording surfaces is three, but any number may be used as long as it is one or more. Further, the error detection method may be another method.
[0038]
[Modification]
Hereinafter, modifications of the disk 1 will be described. In the following description and related drawings, members equivalent to those described above are denoted by the same reference numerals, and detailed description thereof is omitted.
[0039]
The disc 1 according to the first modification shown in FIG. 4A has only one reference surface 7. The height of the reference surface 7 with respect to the guide surface 5 is equal to the distance d between the recording surfaces 4a, 4b, 4c.
[0040]
First, both the spot P1 and the spot P2 are arranged on the guide surface 5. Subsequently, the spot P2 is disposed on the guide surface 5 and the spot P1 is disposed on the reference surface 7. The output difference of the sensor 14 when the spot P1 is located on the guide surface 5 and when it is located on the reference surface 7 is stored.
[0041]
In recording / reproducing with respect to the recording surface 4a, the target value of the sensor 14 for controlling the collimating lens 12 is set to a value equal to the output of the sensor 14 when the spot P1 is positioned on the reference surface 7.
[0042]
In recording / reproduction with respect to the recording surface 4b, the target value of the sensor 14 for controlling the collimating lens 12 is set to a value obtained by adding the above-described output difference to the target value for recording / reproduction of the recording surface 4a.
[0043]
In recording / reproduction with respect to the recording surface 4c, the target value of the sensor 14 for controlling the collimating lens 12 is set to a value obtained by adding twice the above-described output difference to the target value for recording / reproduction of the recording surface 4a.
[0044]
In this modification, since there is only one reference surface, the maximum level difference between the guide surface 5 and the reference surface is small, so that it is easy to form the reference surface.
[0045]
The disc 1 according to the second modification shown in FIG. 4B has only one reference surface 7. The height of the reference surface 7 with respect to the guide surface 5 is equal to half of the distance d between the recording surfaces 4a, 4b, 4c, that is, d / 2.
[0046]
First, both the spot P1 and the spot P2 are arranged on the guide surface 5. Subsequently, the spot P2 is disposed on the guide surface 5 and the spot P1 is disposed on the reference surface 7. The output difference of the sensor 14 when the spot P1 is located on the guide surface 5 and when it is located on the reference surface 7 is stored.
[0047]
For recording / reproduction with respect to the recording surface 4a, the target value of the sensor 14 for controlling the collimating lens 12 is set to a value twice the aforementioned output difference.
[0048]
In recording / reproduction with respect to the recording surface 4b, the target value of the sensor 14 for controlling the collimating lens 12 is set to a value obtained by adding twice the above-described output difference to the target value for recording / reproduction of the recording surface 4a.
[0049]
In recording / reproduction with respect to the recording surface 4c, the target value of the sensor 14 for controlling the collimating lens 12 is set to a value obtained by adding four times the output difference to the target value for recording / reproduction of the recording surface 4a.
[0050]
In the present modification, there is only one reference surface, and the maximum level difference between the guide surface 5 and the reference surface is smaller than that in the first modification, so that it is easier to form the reference surface.
[0051]
The disc 1 according to the third modification shown in FIG. 4C has only one reference surface 7. The height of the reference surface 7 with respect to the guide surface 5 is equal to three times the distance d of the recording surfaces 4a, 4b, 4c, that is, 3d.
[0052]
First, both the spot P1 and the spot P2 are arranged on the guide surface 5. Subsequently, the spot P2 is disposed on the guide surface 5 and the spot P1 is disposed on the reference surface 7. The output difference of the sensor 14 when the spot P1 is located on the guide surface 5 and when it is located on the reference surface 7 is stored.
[0053]
For recording / reproduction with respect to the recording surface 4a, the target value of the sensor 14 for controlling the collimating lens 12 is set to one third of the output difference.
[0054]
In recording / reproducing with respect to the recording surface 4b, the target value of the sensor 14 for controlling the collimating lens 12 is set to a value two-thirds of the output difference.
[0055]
In recording / reproducing with respect to the recording surface 4c, the target value of the sensor 14 for controlling the collimating lens 12 is set to a value equal to the aforementioned output difference.
[0056]
The disc 1 according to the fourth modification shown in FIG. 4 (d) has two reference surfaces 7a and 7b. The height of the reference surface 7a with respect to the guide surface 5 is d0, and the height of the reference surface 7b with respect to the reference surface 7a is equal to twice the distance d of the recording surfaces 4a, 4b, 4c, that is, 2d. d0> d, for example, d0 = 50 μm and d = 10 μm.
[0057]
First, both the spot P1 and the spot P2 are arranged on the guide surface 5. Subsequently, the spot P2 is arranged on the guide surface 5, and the spot P1 is arranged on the reference surface 7a.
[0058]
In recording / reproducing with respect to the recording surface 4a, the target value of the sensor 14 for controlling the collimating lens 12 is set to a value equal to the output of the sensor 14 when the spot P1 is positioned on the reference surface 7a.
[0059]
In recording and reproduction with respect to the recording surfaces 4b and 4c, the spot P1 is further arranged on the reference surface 7b, and the output difference of the sensor 14 when the spot P1 is located on the reference surface 7a and the reference surface 7b is stored. Keep it.
[0060]
In recording / reproduction with respect to the recording surface 4b, the target value of the sensor 14 for controlling the collimating lens 12 is set to a value obtained by adding half of the output difference described above to the target value for recording / reproduction of the recording surface 4a.
[0061]
In recording / reproduction with respect to the recording surface 4c, the target value of the sensor 14 for controlling the collimating lens 12 is set to a value obtained by adding the above-described output difference to the target value for recording / reproduction of the recording surface 4a.
[0062]
The disc 1 according to the fifth modification shown in FIG. 5 (a) has a reference surface 7a located on the inner peripheral side and a reference surface 7b located on the outer peripheral side. The heights of the reference surface 7a and the reference surface 7b with respect to the guide surface 5 are both equal to the distance d between the recording surfaces 4a, 4b, 4c.
[0063]
Recording / reproduction with respect to the disk 1 is performed in the same manner as in the first modification described above.
[0064]
In the present modification, the reference surface is provided at two locations on the inner peripheral side and the outer peripheral side of the disk 1, so that the reference surface can be accessed in a short time.
[0065]
The disc 1 according to the sixth modification shown in FIGS. 5B and 5C has three reference surfaces 7a, 7b, and 7c arranged along the track direction on the inner peripheral side thereof. Yes. The heights of the reference surfaces 7a, 7b, and 7c with respect to the guide surface 5 are d, 2d, and 3d, respectively, where d is the distance between the recording surfaces 4a, 4b, and 4c.
[0066]
Recording and reproduction on the recording surfaces 4a, 4b, and 4c are performed in the same manner as in the above-described embodiment.
[0067]
A more preferable disk is provided with the same reference surfaces 7 a, 7 b, 7 c on the outer peripheral side of the disk 1. As described above, this enables access in a short time.
[0068]
In this modified example, there are three reference surfaces 7a, 7b and 7c, but these do not occupy a large area in the tracking direction, so that it is possible to form a recording track having a wide width. In addition, the interval between the spot P1 and the spot P2 can be reduced.
[0069]
[Second Embodiment]
The recording / reproducing apparatus according to the second embodiment will be described below. The configuration of the recording / reproducing apparatus of the present embodiment is almost the same as that of the first embodiment, except that the functions of some optical elements are slightly different.
[0070]
Specifically, in the present embodiment, in FIG. 1, the support driving unit 13 can move the collimating lens 12 not only in the optical axis direction but also in a direction orthogonal thereto. In response to this, the sensor 14 can detect the position of the collimating lens 12 in the optical axis direction and the orthogonal direction thereof.
[0071]
A hologram is used in place of the toric lens 21, a focus error is detected by the beam size method, and a tracking error is detected by the push-pull method.
[0072]
As described above, the present embodiment is different from the first embodiment in that the support driving means and the sensor for the collimating lens are different in terms of functions. Omitted.
[0073]
As shown in FIG. 6, the disk 1 has a base layer 2 and a recording layer 3, and seven recording surfaces 4 a to 4 g can be formed on the recording layer 3 with a constant equal interval d. . The base layer 2 has a guide surface 5, a reference surface 7, and a surface 8. The guide surface 5 has two tracks 6a and 6b that are arranged at a constant interval e. The reference surface 7 has a height of 3d with respect to the guide surface 5.
[0074]
The surface 8 is located in a region where the recording surfaces 4 a to 4 g are formed, and has a high reflectance like the guide surface 5. The recording surface 4g is formed at the same height as the reference surface 7, and the recording surface 4a is formed at a position relatively far from the surface 8 so that the reflected light from the surface 8 becomes sufficiently small.
[0075]
First, both the recording / reproducing spot P1 and the guide spot P2 are fixed to one track 6a of the guide surface 5, and the outputs of the sensor 14 in the focus direction and the track direction are reset.
[0076]
Next, the collimating lens 12 is moved in the track direction, and only the spot P1 is positioned on the track 6b (denoted by P1 ′). Based on the output of the sensor 14 at this position, the reference value in the tracking direction of the spot P1 and the spot P2, that is, the track interval e is obtained.
[0077]
Subsequently, with the spot P2 fixed to the track 6a of the guide surface 5, the collimating lens 12 is moved in the track direction and the optical axis direction, and the spot P1 is positioned on the reference plane 7 (denoted by P1 ″). Based on the output of the sensor 14 at this position, a reference value d in the focus direction of the spots P1 and P2 is obtained.
[0078]
In the present embodiment, recording / reproduction is performed at predetermined intervals in two directions of the focus direction and the tracking direction with respect to the spot P2 while the guide spot P2 is held on the track 6a of the guide surface 5 in the recording / reproduction. To be done.
[0079]
Specifically, the spot P1 is moved forward or backward from the guide surface 5 with respect to the focus direction by a desired integer multiple of the reference value d, and with respect to the track direction, a desired reference value e of the reference value e is moved outward from the track 6a. The position with respect to the spot P2 is determined by moving by an integral multiple. Recording and reproduction are performed while maintaining the relative position with respect to the spot P2.
[0080]
Although several embodiments have been specifically described so far with reference to the drawings, the present invention is not limited to the above-described embodiments, and all the embodiments performed without departing from the scope of the invention are not limited thereto. Including implementation.
[0081]
This specification includes the inventions listed below.
[0082]
1. An optical recording apparatus for optically recording and / or reproducing information on an optical recording medium having at least one recording unit and a guide unit, and recording and / or reproducing information by irradiating the recording unit with light The first light to be emitted and the second light to irradiate the guide part with light, the second light is applied to the guide part, and the relative position of the first light with respect to the second light. In the recording apparatus for positioning the first light in the recording unit by controlling the recording unit, one of the recording units has a first interval in a first direction with respect to the guide unit, and the optical recording The medium has a reference portion having a second interval, and the reference portion is irradiated with the first light to obtain a reference signal having the first interval. Playback method.
[0083]
2. The first term is characterized in that the first direction is a focus direction.
[0084]
3. In the first item, the reference portion is disposed on the inner peripheral side of the recording medium.
[0085]
4. In the first item, the reference portion is disposed on the outer peripheral side of the recording medium.
[0086]
5. In the first item, the first interval is the same as the second interval.
[0087]
6. In item 1, there are at least two recording units.
[0088]
7. In item 6, the interval between two adjacent recording sections is the same as the second interval.
[0089]
8. In the first item, there are a plurality of the reference parts.
[0090]
9. In the first item, there are a plurality of the second intervals.
[0091]
10. In the first item, when the recording unit is irradiated with the spot of the first light, detection of a shift between the first light spot and the recording unit in the first direction is detected. Don't do it with light.
[0092]
11. In the first item, the same number of the reference parts as the number of the recording parts is provided.
[0093]
12. In the first item, the same number of the reference parts as the number of the recording parts is provided.
[0094]
13. In the sixth aspect, the second interval has an interval between the recording portion and the guide portion which are farthest from the guide portion.
[0095]
14. An optical recording apparatus for optically recording and / or reproducing information on an optical recording medium having at least one recording unit and a guide unit, and recording and / or reproducing information by irradiating the recording unit with light The first light to be emitted and the second light to irradiate the guide part with light, the second light is applied to the guide part, and the relative position of the first light with respect to the second light. In the recording apparatus for positioning the first light in the recording unit by controlling the recording medium, the recording medium has a reference unit having a predetermined interval with respect to the relative position.
[0096]
15. In Item 14, further comprising means for irradiating light to the reference portion.
[0097]
16. In an optical recording medium having at least one recording section and a guide section, the recording section and the guide section are spaced apart from each other by a first distance in the first direction and have a second distance in the first direction. An optical recording medium comprising:
[0098]
【The invention's effect】
According to the present invention, the recording / reproducing spot is stably arranged at a certain height from the guide surface according to the reference value obtained based on the reference surface, so that stable information recording / reproducing can be performed.
[Brief description of the drawings]
FIG. 1 shows an optical system of a recording / reproducing apparatus in a first embodiment of the present invention.
2 shows the optical system of the recording / reproducing apparatus of FIG. 1 viewed from another angle, in which the inclination of the optical axis of the guide optical system is exaggerated.
FIG. 3 is an enlarged view of a cross section and an objective lens of the optical disc shown in FIG.
4A is a first modification of an optical disc, FIG. 4B is a second modification of the optical disc, FIG. 4C is a third variation of the optical disc, and FIG. 4D is a fourth variation of the optical disc. Yes.
FIG. 5A shows a fifth modification of the optical disc, and FIGS. 5B and 5C show a sixth modification of the optical disc.
FIG. 6 shows a cross section of an optical disc in a second embodiment of the present invention.
[Explanation of symbols]
1 disc
2 Base layer
3 Recording layer
4a, 4b, 4c Recording surface
5 Guide surface
6 tracks
7a, 7b, 7c Reference plane

Claims (3)

An optical recording medium on which a plurality of recording surfaces can be formed;
Having a base layer and a recording layer provided thereon,
The recording layer can have a plurality of recording surfaces formed therein,
The base layer has a guide surface on which tracks are formed, and at least one reference surface that is formed at a different height from the guide surface and that provides a reference value for the interval between the recording surfaces formed in the recording layer. An optical recording medium. A recording / reproducing apparatus for recording / reproducing information with respect to the optical recording medium according to claim 1,
A first optical system for forming a guide spot;
A second optical system for forming a recording / reproducing spot;
Means for holding the guide spot on the guide surface;
Means for changing the height of the recording / reproducing spot with respect to the guide spot;
The height of the reference surface relative to the guide surface is obtained from the difference in height between the recording / playback spot located on the guide surface and the recording / playback spot located on the reference surface, and based on this, the reference value of the recording surface interval is determined. Having means to obtain,
Based on the obtained reference value, the recording / reproducing spot is arranged at a desired height that is an integral multiple of the reference value with respect to the guide spot, and recording is performed with the recording / reproducing spot while the guide spot is held on the guide surface. A recording / reproducing apparatus for performing reproduction. A method for recording and reproducing information with respect to the optical recording medium according to claim 1,
Arranging a spot for recording and a spot for recording / reproducing on the guide surface;
Arranging the recording / reproducing spot on the reference plane;
Based on the height change of the recording / reproducing spot, obtaining the height of the reference surface relative to the guide surface, and obtaining the reference value of the interval between the recording surfaces based on this,
Based on the obtained reference value, placing the recording / reproducing spot at a desired height that is an integer multiple of the reference value from the guide surface;
And recording / reproducing with the recording / reproducing spot while holding the guide spot on the guide surface.

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