JP3691326B2 - Stamper, optical information medium substrate, optical information medium, and recording method therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stamper used at the time of molding, an optical information medium substrate formed by the stamper, and an optical information medium on which information optically reproducible can be recorded using the substrate, and in particular, a short wavelength of 630 to 670 nm. The present invention relates to one having a sector information detecting means optimum for a high-density recording medium recorded and reproduced by a red laser beam.
[0002]
[Prior art]
With the recent development and practical application of short wavelength lasers, the practical application is progressing with the standardization of the DVD (Digital Versatile Disc) standard that enables higher density recording and reproduction. In this DVD, a data recording area is set on at least one main surface, pits as information recording means are formed in the data recording area, and a reflective layer made of a metal film is formed thereon.
[0003]
In the DVD, different standards are set for higher density than the CD (Compact Disc) which is the most common standard of optical information media at present. For example, in an optical pickup, a short wavelength red laser having a wavelength of 630 nm to 670 nm is used, and a high aperture ratio objective lens having an aperture ratio NA of 0.6 is used.
[0004]
Along with this, in order to cope with the warp of the disc, a disc having a thickness of about half that of a CD of 0.6 mm is employed. However, in order to ensure dimensional compatibility with a CD having a disk thickness of 1.2 mm, a two-disk bonding structure is employed. In the DVD standard, it is standardized that a maximum recording capacity is about 4.7 GB as a standard on one disc and that an average of about 133 minutes of video and audio is recorded.
[0005]
Until now, in a recordable CD such as a CD-R, the wobble of a spiral groove-shaped tracking guide is FM-modulated to obtain address information called ATIP (Absolute Time In Pregroove). In contrast, in a recordable DVD such as a DVD-R, address information such as position information on an optical information medium is obtained by prepits provided in advance in land portions between tracking guides together with wobbles instead of ATIP.
[0006]
[Problems to be solved by the invention]
The pre-pits adopted in the DVD, which is a high-density recording medium as described above, are read together with the pits of the recording signal by the optical pickup. At this time, the optical pickup is tracking-servoed along the tracking guide, so that the normal state In this case, the pre-pit and the pit on which the data signal formed on the groove is recorded are discriminated and read. However, depending on the shape and size of the prepit, the prepit may be mixed and read into the RF signal obtained from the data signal recording pit. In this case, an error occurs in reading the data signal.
[0007]
In DVD-R and DVD-RW, a pre-pit is necessary for obtaining address information such as position information on an optical information medium at the time of recording. However, it is not used at the time of reproduction, and mixing of the signal obtained from the pre-pit into the RF signal indicating the recording data causes an error in reading the RF data signal.
On the other hand, however, if the prepits are difficult to read at the time of recording, there is a problem that information such as addresses at the time of recording cannot be read normally and recording becomes unstable, thereby making it impossible to reproduce the recording signal itself.
[0008]
In the present invention, in view of the problems associated with reading pre-pits for reading address information of an optical information medium that supports high-density recording as described above, the object is to access the unrecorded area and move the pickup to the recording start position. It is possible to reliably read the address signal from the prepit at the time of recording, including movement information at the time of recording, and when the recorded signal is optically read, the signal obtained from the prepit indicating the address information and the tracking guide Optical information medium capable of eliminating reading errors due to interference with recorded data read from pits and eliminating signal obtained from pre-pits in data signals during reproduction, optical information medium substrate, and substrate molding Is to provide a stamper.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, the prepit 6 provided on the land 8 indicating the address information is intentionally shifted from the land 8, thereby increasing the strength to the tracking error signal, and Leakage into the RF signal is weak, so that it can be clearly discriminated from the RF signal obtained from the pits on the groove 3 to prevent them from being read erroneously.
[0010]
  The stamper according to the present invention is a stamper that is formed concentrically or spirally and has uneven steps, and the recess of the stamper23The concavePart 23Convex part adjacent to24Projection that leads to at least one of22Is providedBoth ends of the connecting portion between the projecting portion 22 and the projecting portion 24 are connected to the boundary portion between the recessed portion 23 and the projecting portion 24 in a substantially curved shape toward the outside of the projecting portion 22 when viewed in plan.It is characterized by.
  An optical information medium substrate according to the present invention is a substrate for an optical information medium that is formed concentrically or spirally and is resin-molded by a stamper having uneven steps, and the substrate includes a concave portion of the stamper.23Provided in the concavePart 23Convex part adjacent to24Projections that connect to at least one22Show address information byConcavePre-pit6Is provideding. A raised rim 7 lower than the height of the land 8 from the bottom surface of the tracking guide 3 is formed at the opening of the prepit 6 where the prepit 6 is connected to the land 8. Further, both ends of the opening of the prepit 6 are formed so as to contact the boundary between the tracking guide 3 and the land 8 in a substantially curved shape toward the outside of the prepit 6 when seen in a plan view.It is characterized by being.
[0011]
  An optical information medium according to the present invention includes a translucent substrate 1 that transmits recording light, a recording layer 12 formed on the translucent substrate 1, and a recording layer 12 that is formed on the recording layer 12 and reflects reproduction light. And a reflective layer 13 that records an optically readable signal by recording light incident from the translucent substrate 1. In the present invention, such an optical information medium has a spiral groove-shaped tracking guide 3 on the surface side of the translucent substrate 1 on which the recording layer 12 is formed. Show address informationConcaveA prepit 6 is formed, and the prepit 6 is formed so as to be shifted from the center of the land 8. As a result, the pre-pit 6 is open to the tracking guide 3 side adjacent to the land 8.A raised rim 7 having a height lower than the height of the land 8 from the bottom surface of the tracking guide 3 is formed at the opening of the land 8 of the prepit 6. Further, both ends of the opening of the prepit 6 are formed so as to contact the boundary between the tracking guide 3 and the land 8 in a substantially curved shape toward the outside of the prepit 6 when seen in a plan view.Has been.
  In the recording method of the optical information medium according to the present invention, the optical information medium as described above can be optically read while tracking the recording light incident from the translucent substrate 1 along the tracking guide 3. Record the signal.
[0012]
An optical information medium substrate formed by using such a stamper and this stamper. In the optical information medium using this substrate, the prepit 6 is formed off the center of the land 8, and thus more specifically. Since the prepit 6 is formed so as to be shifted from the center of the land 8 in the inner circumferential direction of the disk, it is formed as a prepit that is closer to the center of the beam spot at the time of tracking. A signal amplitude larger than that formed at the center can be obtained, and the reading can be performed reliably.
[0013]
Further, by configuring as described above, the shape of the prepit 6 can be made smaller than when the prepit 6 is formed at the center of the land 8. This is because, as described above, the prepit 6 is offset from the center of the land 8 in the inner circumferential direction of the disk, thereby obtaining a larger signal amplitude than when the prepit is formed at the center of the land 8. In this case, the shape of the prepit 6 can be physically reduced to a level at which the signal amplitude can be read (for example, the signal amplitude when the prepit 6 is formed at the center of the land 8). Even when the signal from the pre-pit leaks into the RF signal, it is sufficiently smaller than the time length of the minimum signal as the data signal when it is decoded into the EFM signal. Thus, it is possible to prevent erroneous reading of signals from the prepits.
[0014]
For example, when the data pit formed on the tracking guide 3 is read while tracking servo of the optical pickup along the tracking guide 3, the signal obtained from the pre-pit 6 is further weaker than the signal obtained from the data pit. . As a result, the signal of the pre-pit 6 mixed in the RF signal obtained from the data pit becomes weak, and mixing of noise into the data signal hardly causes a problem.
[0015]
It is preferable that the prepit 6 is shifted in the inner peripheral direction of the translucent substrate 1 with respect to the center of the land 8. This is because, as described above, by forming the prepit as closer to the center of the beam spot during tracking, the prepit reproduction signal obtains a larger signal amplitude than when the prepit is formed at the center of the land 8. is there.
[0016]
The pitch p of the tracking guide 3 is 0.74 μm, and the half width w is preferably in the range of 0.23 μm ≦ w ≦ 0.38. Further, the half width d of the prepit 6 is preferably 0.20 μm ≦ d ≦ 0.33. From this relationship, the ratio w / d between the half-value width w of the tracking guide 3 and the half-value width d of the prepit 6 is 0.5 ≦ w / d ≦ 1.7. The offset dimension δ from the center of the land 8 of the prepit 6 is preferably 0 μm ≦ δ ≦ 0.2 μm depending on the width of the land 8, and is from the boundary between the tracking guide 3 and the land 8 to the prepit 6. The width l is preferably in the range of 0 μm ≦ l ≦ 0.2 μm.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described specifically and in detail with reference to the drawings.
As an example of the optical information medium according to the present invention, an example of a write-once type optical information medium having a single-side recording / reproducing structure by double-side bonding is shown in FIGS.
The translucent substrate 1 is a transparent disk-shaped substrate having a center hole 4 in the center. The translucent substrate 1 is generally made by injection molding a transparent resin such as polycarbonate or polymethyl methacrylate (PMMA).
[0018]
  Here, when the translucent substrate 1 is formed, a stamper 21 that is formed concentrically or spirally and has uneven steps as shown in FIG. 7 is used. The concave portion 23 of the stamper 21 is provided with a protruding portion 22 that leads to at least one of the convex portions 24 adjacent to the concave portion 23, in this case, the convex portion 24 on the inner peripheral side.
  In addition,As is apparent from FIG. 7, both ends of the connecting portion between the protruding portion 22 and the protruding portion 24 are substantially curved at the boundary between the recessed portion 23 and the protruding portion 24 toward the outside of the protruding portion 22 when viewed in plan. It is connected to. Also,The connecting portion between the projecting portion 22 and the convex portion 24 has a shape in which sagging occurs or rises.
[0019]
In the optical information medium substrate molded by the stamper 21, a projecting land 8 is formed on the substrate 1 by the recess 23 of the stamper 21, and a concave tracking is formed on the substrate 1 by the projecting portion 24 of the stamper 21. A guide 3 is formed. Further, a concave prepit 6 indicating address information is provided on the substrate 1 by a protruding portion 22 formed in a concave portion 23 of the stamper 21 so as to be continuous with the convex portion 24 of the stamper 21. The pre-pit 6 is formed in a part of the land 8 adjacent to the tracking guide 3 so as to be continuous with the tracking guide 3 on the substrate 1.
[0020]
A clamping area is set outside the center hole 4 on one side of the translucent substrate 1 having translucency, and the outer peripheral side of the clamping area is a data recording area. A tracking guide 3 made of a spiral groove is formed in the data recording area of the translucent substrate 1. A standard pitch of the tracking guide 3 is 0.74 μm.
[0021]
As shown in FIGS. 3 to 6, in the land 8 between the tracking guides 3, concave prepits 6 for indicating address information and the like are formed at appropriate intervals when signals are recorded on the optical information medium. Has been. The pre-pit 6 is formed in advance together with the tracking guide 3 at the time of injection molding of the translucent substrate 1.
[0022]
As shown in these drawings, the pre-pit 6 is formed with an offset dimension δ shifted from the center of the land 8. For this reason, the prepit 6 is open on one edge side of the land 8. The pre-pit 6 is displaced in the same direction with respect to the center of the land 8, and in the illustrated example, the pre-pit 6 is open on the left side of the land 8 in FIG. A raised rim 7 is formed in the open portion. As a matter of course, the depth of the rim 7 is lower than the depth of the tracking guide 3 and the prepit 6, that is, the height of the land 8 from the bottom surface of the tracking guide 3. The rim 7 may be interrupted on the way.
[0023]
Since this rim portion is lower than the height of the land 8, the contribution to the amount of reflected light at the land portion is reduced during laser beam irradiation. In order to maximize the LPP signal amplitude at this time, it is advantageous that the reflected light amount of the land portion is small, and it is desirable that the rim portion is low.
[0024]
The offset dimension δ of the prepit 6 with respect to the center of the land 8 is preferably 0 μm ≦ δ ≦ 0.2 μm, depending on the width of the land 8, and from the boundary between the tracking guide 3 and the land 8 to the prepit 6. The width l is preferably in the range of 0 μm ≦ l ≦ 0.2 μm. Incidentally, the pitch p of the tracking guide 3 is 0.74 μm, and its half width w is in the range of 0.23 μm ≦ w ≦ 0.38 μm.
[0025]
The diameter d of the prepit 6 is different from the length of the pit formed on the optical information medium at the time of recording. For example, in a DVD, the data pit length is about 0.4 to about 1.9 μm, but the diameter d of the prepit 6 is made shorter than the minimum pit length of 0.4 μm. More specifically, the diameter d of the prepit 6 is set to 50 to 83% of the minimum pit length. For example, in DVD, the minimum pit length is 3 channel clocks, but the length of the prepit 6 is 1.5 to 2.5 channel clocks. Specifically, the diameter d of the prepit 6 is 0.20 μm ≦ d ≦ 0.33 μm. From this relationship, the ratio w / d between the half-value width w of the tracking guide 3 and the half-value width d of the prepit 6 is 0.5 ≦ w / d ≦ 1.7. In this way, necessary signal outputs can be obtained for each of the data pits formed on the tracking guide 3 and the pre-pits formed on the lands 8, and the signals of the two do not interfere with each other. It is possible to suppress the signal leakage due to the pre-put.
[0026]
Further, as shown in FIG. 3, both ends of the opening of the prepit 6 formed in the land 8 are tracked in a substantially curved shape outward from the outer periphery of the prepit in plan view as indicated by reference numeral 6a. It is desirable to form it so as to contact the boundary between the guide 3 and the land 8. In this way, the surface shape of the prepit 6 expands at that portion, so that when viewed optically, the contribution to the reflected light quantity of the land 8 portion is reduced, and the prepit signal amplitude can be increased. Therefore, even when the shape of the prepit is smaller than the variation reference shape, it is possible to ensure the output of the prepit signal at the reference shape as the output signal, and to reduce the prepit signal reading error.
[0027]
Further, as shown in FIGS. 1, 2, 5, and 6, a recording layer 12 is formed on the main surface of the data recording area portion of the translucent substrate 1. For example, an organic dye or the like is applied by means such as a spin coating method, and the recording layer 12 is formed.
FIG. 5 and FIG. 6 are both shown as a cross section in the radial direction of the translucent substrate 1. As is apparent from FIG. 6, the prepit 6 is shifted to the left side of the land 8, that is, the inner peripheral side of the disc, and as a result, the left side of the land 8 is open. Further, a raised rim 7 shallower than the depth of the tracking guide 3 is formed in a portion of the prepit 6 that is open on one side of the land 8.
[0028]
Here, in general, the intensity of the laser beam has the strongest normal distribution at the center thereof, and when the prepit 6 is offset to the inner periphery of the land 8 as described above, the prepit 6 is used during tracking. Is closer to the center of the beam, more diffraction intensity can be obtained than when the prepit is located at the center of the land 8.
The pre-pit 6 is used to obtain a signal that is address information of the optical information medium. However, the pre-pit 6 may be used together with the pre-pit 6 to obtain rotation control information by wobbling of the tracking guide 3.
[0029]
As shown in FIG. 1, FIG. 2, FIG. 5 and FIG. 6, a reflection made of a metal film such as gold, aluminum, silver, copper or an alloy film thereof on the recording layer 12 formed as described above. Layer 13 is formed. Further, a protective film 14 such as an ultraviolet curable resin is formed on the reflective layer 13.
As shown in FIGS. 1 and 2, another substrate 5 is prepared in addition to the translucent substrate 1. This substrate 5 is made of the same material as that of the translucent substrate 1 and has the same size, and the main surface thereof has a tracking guide 3 such as the translucent substrate 1, a recording layer 12, and a reflective layer. 13 is not provided. Of course, the recording layer 12, the reflective layer 13, and the like can be provided on the other substrate 5 on the substrate 5 having the tracking guide 3, as in the case of the translucent substrate 1.
[0030]
Next, these two substrates 1 and 5 are bonded together. For example, a reactive curable resin is applied as an adhesive to at least one main surface of the two substrates 1 and 5 by means such as spin coating or screen printing, and these surfaces are overlapped with each other facing each other. And the reactive curable resin is cured. Thereby, the main surfaces of the two substrates 1 and 5 are bonded together by the adhesive layer 11 formed by curing the reactive curable resin. In this case, the surface on which the recording layer 12 and the reflective layer 13 are formed is bonded to the translucent substrate 1.
[0031]
In the above example, the translucent substrate 1 in which the recording layer 12 and the reflective layer 13 are formed on the translucent substrate having the tracking guide 3 and the other substrate in which the recording layer 12 and the reflective layer 13 are not formed. 5 is an example of pasting together. In these cases, only one side can be recorded / reproduced. The other substrate 5 may be one that does not have translucency, one that is colored to maintain light resistance, or one that is provided with a character, pattern, or writable region on the surface.
[0032]
On the other hand, two light-transmitting substrates 1 each having a recording layer 12 and a reflecting layer 13 provided on a light-transmitting substrate 1 having a tracking guide 3 are prepared, and the recording layer 12 and the reflecting layer 13 side are provided. An optical information medium having a so-called double-sided recording / reproducing structure that is bonded to face to face can also be used.
1 and 2, reference numeral 9 denotes a protrusion 9 formed in a ring shape outside the data recording area r on the recording light incident surface side on the front side of the translucent substrate 1. This is to prevent the recording surface from touching the surface of another optical information medium when the optical information medium is overlaid.
[0033]
【Example】
Next, examples of the present invention will be described with specific numerical values.
Example 1
A photosensitizer (photoresist) is applied very thinly on the polished glass substrate, and cutting is performed by running a laser beam spirally from the inner periphery to the outer periphery while rotating the glass disk. The cutting machine is called an LBR (laser beam recorder) and uses a krypton / argon laser having a wavelength of 351 to 458 nm as a light source. This laser beam is a mastering signal applied to an optical modulator capable of adjusting the intensity of electrically transmitted light, and strikes a spot in a spiral shape on a rotating photosensitive film while wobbling. At that time, the laser beam that has passed through another irradiation path is turned ON / OFF at a predetermined timing, and the exposed portion of the photosensitive film is melted with a dedicated developer to form a groove and a prepit in the portion. Thereafter, a conductive agent is coated on the surface, Ni plating is applied to the surface of the photosensitive film using the conductive agent as an electrode, and this is removed to obtain a master stamper. Furthermore, a mother stamper can be obtained by plating the surface of the master stamper as an electrode and peeling it off as described above.
[0034]
By molding the resin using the stamper thus formed, a polycarbonate substrate having an outer diameter of 120 mmφ, an inner diameter of 15 mmφ, a thickness of 0.597 mm, and a refractive index of 1.59 is provided. A translucent substrate 1 having a tracking guide 3 having a diameter of .31 μm, a depth of 140 nm, and a pitch of 0.74 μm was prepared. A plurality of prepits 6 having a half width of the diameter d of 0.27 μm and a variation of ± 0.02 μm are formed in the land 8 between the tracking guides 3. The prepits 6 are offset by a maximum of 0.1 μm, a minimum of 0.05 μm, and an average of 0.07 μm.
A film of cyanine dye was spin-coated on the surface of the translucent substrate 1 having the tracking guide 3 to form a film.
[0035]
Further, Au was sputtered on the recording layer 3 to form a reflective layer 13. A UV curable resin (SD211 manufactured by Dainippon Ink & Chemicals, Inc.) was spin-coated thereon, and this was cured by irradiating with ultraviolet rays to form a protective layer 14. An adhesive made of an ultraviolet curable resin was applied to the protective layer 14, a substrate having the same material and shape as those described above was bonded, and the adhesive was cured by irradiating with ultraviolet rays to be bonded. This made an optical information medium.
[0036]
With respect to the optical information medium thus produced, when an address signal was read using an optical pickup (aperture ratio 0.6) that emits laser light having a wavelength of 637 nm, the address information could be stably extracted. In addition, an 8/16 modulation signal (8 bits converted to 16 bits) was recorded at a recording power of 10 mW using the same system. When the recorded optical information medium was reproduced by a DVD player, the data signal reading PI error was 3 counts per 8 ECC blocks (average value per minute), and stable reproduction was possible. The recorded signal had a modulation degree of 61%, a maximum value of the length error between the pits and lands 8 of each signal was 6.0 ns, and a jitter of 7.5%.
[0037]
(Example 2)
An optical information medium was fabricated in the same manner as in Example 1, except that the half width of the diameter d of the land prepit 6 was 0.28 μm and the variation was ± 0.02 μm.
With respect to the optical information medium produced in this way, when an optical pickup (aperture ratio 0.6) that emits laser light having a wavelength of 650 nm was used and sector information was read, address information could be stably extracted. The system was used to record an 8/16 modulated signal (converted from 8 bits to 16 bits) at a recording power of 10.5 mW. When the recorded optical information medium was reproduced by a DVD player, the data signal reading PI error was 5 counts per 8 ECC blocks (average value per minute), and stable reproduction was possible. The recorded signal had a modulation degree of 65%, the maximum length error between the pits and lands 8 of each signal was 5.8 ns, and the jitter was 7.3%.
[0038]
(Comparative Example 1)
In the first embodiment, the offset amount of the prepit 6 from the center of the land 8 toward the outer periphery of the disk is 0.1 μm, the half width d of the land prepit 6 is 0.41 μm, and the half width w of the tracking guide 3 is 0.20 μm. An optical information medium was manufactured in the same manner as in Example 1 except that the half width d of the land prepits 6 and the ratio w / d = 0.49 of the half width w of the tracking guide 3 were set.
With respect to the optical information medium produced in this way, when an optical pickup (aperture ratio 0.6) that emits laser light having a wavelength of 635 nm was used and sector information was read, address information could be stably extracted. The system was used to record an 8/16 modulated signal (converted from 8 bits to 16 bits) at a recording power of 10.0 mW. When the recorded optical information medium is reproduced by a DVD player, the PI error of reading data signals is 300 counts per 8 ECC blocks (average value per minute), which is not preferable for data reproduction. there were. The degree of modulation of the recorded signal was 65%, the maximum length error of the pits and lands 8 of each signal was 6.5 ns, and the jitter was 9%.
[0039]
(Comparative Example 2)
An optical information medium was manufactured in the same manner as in Example 1, except that the deviation of the land pre-pit 6 was 0.3 μm at maximum, 0.2 μm at minimum, and 0.25 μm on average.
With respect to the optical information medium thus produced, when an address signal was read using an optical pickup (aperture ratio 0.6) that emits laser light having a wavelength of 650 nm, the address information could not be read.
[0040]
【The invention's effect】
As described above, in the optical information medium according to the present invention, an optical pickup can be used to optically record a signal on an optical information medium compatible with high-density recording, and the address signal can be reliably read from the prepits during recording. In addition, when the recorded signal is optically read, the address information at the time of recording is eliminated by eliminating a reading error between the signal obtained from the land pre-pit indicating the sector information and the recording data read from the pit on the tracking guide. And the data signal at the time of reproduction can be accurately separated and read.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a half section of a state before two substrates are bonded to each other, showing an example of an optical information medium according to the present invention.
FIG. 2 is a partial longitudinal sectional perspective view showing the optical information medium.
FIG. 3 is a plan view of an essential part showing a part of a translucent substrate used in the optical information medium.
4 is a perspective view showing a cross section at the position AA in FIG. 3; FIG.
FIG. 5 is a longitudinal side view of a main part of the optical information medium.
FIG. 6 is an enlarged vertical side view of the main part of the optical information medium.
FIG. 7 is a perspective view of a stamper.
[Explanation of symbols]
1 Translucent substrate
3 Tracking guide
6 Prepit
8 rand
12 Recording layer
13 Reflective layer
21 Stamper

Claims (10)

A stamper formed concentrically or spirally and having uneven steps, and the recess (23) of the stamper is connected to at least one of the protrusions (24) adjacent to the recess (23). A projecting portion (22) is provided , and both ends of the connecting portion between the projecting portion (22) and the projecting portion (24) are substantially curved toward the outside of the projecting portion (22) when viewed in plan. A stamper characterized by being connected to a boundary portion between the concave portion (23) and the convex portion (24) . In an optical information medium substrate that is formed in a concentric or spiral shape and is resin-molded by a stamper (21) having uneven steps, the concave portion (23) of the stamper (21) projects onto the substrate (1). The land (8) is formed, the protrusion (24) of the stamper (21) forms a concave tracking guide (3) on the substrate (1), and the protrusion (24) of the stamper (21). ) Is formed on the substrate (1) by a protrusion (22) formed in the recess (23) of the stamper (21) so as to be connected to the stamper (21). 6) is formed on a part of the land (8) adjacent to the tracking guide (3) so as to be continuous with the tracking guide (3) on the substrate (1) , and the prepit (6) is connected to the land (8). Na An optical information medium substrate, wherein the land (8) of height less than the ridged rim from the bottom of the opening tracking guide (3) (7) is formed of the same pre-pits (6). In an optical information medium substrate that is formed in a concentric or spiral shape and is resin-molded by a stamper (21) having uneven steps, the concave portion (23) of the stamper (21) projects onto the substrate (1). The land (8) is formed, the protrusion (24) of the stamper (21) forms a concave tracking guide (3) on the substrate (1), and the protrusion (24) of the stamper (21). ) Is formed on the substrate (1) by a protrusion (22) formed in the recess (23) of the stamper (21) so as to be connected to the stamper (21). 6) is formed on a part of the land (8) adjacent to the tracking guide (3) so as to be continuous with the tracking guide (3) on the substrate (1), and the prepit (6) is connected to the land (8). Na Both ends of the opening of the prepit (6) are in contact with the boundary between the tracking guide (3) and the land (8) in a substantially curved shape toward the outside of the prepit (6) in plan view. A substrate for optical information media, which is formed . A translucent substrate (1) that transmits recording light, a recording layer (12) formed on the translucent substrate (1), and formed on the recording layer (12) to reflect reproduction light In an optical information medium for recording an optically readable signal by recording light incident from the translucent substrate (1), the translucent substrate (1) has a reflective layer (13). On the surface side on which the recording layer (12) is formed, a spiral groove-shaped tracking guide (3) is provided, and a concave pre-pit (6) indicating address information is formed on a land (8) between the tracking guides (3). ), And the prepit (6) is formed so as to be offset from the center of the land (8), so that the prepit (6) is open to the tracking guide (3) side adjacent to the land (8). , Tracking in the opening of this pre-pit (6) Optical information medium, characterized in that id (3) Rimland height less than the ridge-shaped (8) from the bottom (7) is formed. A translucent substrate (1) that transmits recording light, a recording layer (12) formed on the translucent substrate (1), and formed on the recording layer (12) to reflect reproduction light In an optical information medium for recording an optically readable signal by recording light incident from the translucent substrate (1), the translucent substrate (1) has a reflective layer (13). On the surface side on which the recording layer (12) is formed, a spiral groove-shaped tracking guide (3) is provided, and a concave pre-pit (6) indicating address information is formed on a land (8) between the tracking guides (3). ) Is formed, and the prepit (6) is formed so as to be shifted from the center of the land (8), so that the prepit (6) is open to the tracking guide (3) side adjacent to the land (8), Both ends of the opening of the prepit (6) are Optical information medium, characterized in that it is formed in contact with the boundary of the substantially curved outward tracking guide (3) and the land (8) of the planarly viewed prepit (6). The optical information medium according to claim 4 or 5 , wherein the prepit (6) is displaced in the inner peripheral direction of the translucent substrate (1) with respect to the center of the land (8). 6. The optical information medium according to claim 4 , wherein an offset dimension δ of the prepit (6) from the center of the land (8) is 0 μm ≦ δ ≦ 0.2 μm. 6. The optical information medium according to claim 4 , wherein the width l from the boundary between the tracking guide (3) and the land (8) to the prepit (6) is 0 μm ≦ l ≦ 0.2 μm. . The ratio w / d between the half-width d of the half-width w and land pre-pit (6) of the tracking guide (3) is 4 or claim characterized in that it is a 0.5 ≦ w / d ≦ 1.7 5. An optical information medium according to 5 . A translucent substrate (1) that transmits recording light, a recording layer (12) formed on the translucent substrate (1), and formed on the recording layer (12) to reflect reproduction light In the method of recording an optical information medium, an optically readable signal is recorded on the optical information medium having the reflective layer (13) that is recorded by the recording light incident from the translucent substrate (1). The optical information medium according to any one of Items 4 to 9 , wherein the optically readable signal is recorded while tracking the recording light incident from the translucent substrate (1) along the tracking guide (3). For recording an optical information medium .

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