JPH05342634A - Flat planar information recording carrier and stamper - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to improve transferability of a prepit portion by injection molding in an optical disc for recording between grooves. [Structure] By making the groove portion adjacent to the pre-pit 3a formed in the groove portion discontinuous such as eliminating the groove like the pit rows 7 and 8, molten resin can easily flow during injection molding. Therefore, it is possible to manufacture an optical disk which can faithfully transfer the unevenness of the pre-pit portion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-groove recording disk in the optical disk field capable of increasing the capacity and density of information.

[0002]

2. Description of the Related Art In recent years, optical discs have features such as high recording density and long life of the medium because recording and reproduction can be performed in a non-contact manner, and random access is faster than a medium such as a tape. A number of systems have been proposed to realize recording / playback such as document files.

As a medium for recording and reproducing these data,
In order to record information with high density, information such as a spiral or concentric circular guide groove called a pre-groove, an address indicating the position of the guide groove, and a sector is recorded in advance between the guide grooves and between the guide grooves. It is formed between the grooves in the shape of a row of protrusions called pits, and is used for servo of the light beam for recording and reproducing information and for confirming the recording position.

A conventional optical disc structure will be described below. FIG. 3A shows a schematic diagram of a disk which is an example of the related art. The disk has a guide groove (track) 11 for guiding a light beam and a groove 12 sandwiched between the guide grooves, and an ID giving information for identifying a track number, a sector number, etc. due to an uneven structure. The portion of the pre-pit 13 such as the control track portion that gives the information specific to the disc or the disc is formed on the base substrate 9.

By the way, the disk is in the form of a plastic substrate such as acrylic or polycarbonate. Most of these plastic substrates are manufactured by injection molding (injection method). The injection molding method is one in which a resin material melted at a high temperature is extruded into a mold to produce a substrate. In order to form the above-mentioned guide grooves and pre-pits, as shown in FIG. 3 (b), a guide groove, ID information, control track information, etc., which is generally called a stamper and is necessary for the disc as unevenness, is formed on a part of the mold. A plate containing is attached, and a metal mold to be the reproduction surface side of the substrate is attached to the opposite side at a distance that will be the thickness of the substrate considering the shrinkage rate of the resin, and the molten resin material is injected from the center. Then, the molten resin material gradually flows between the stamper and the mold while being cooled, so that the surfaces of the stamper and the mold are transferred to the substrate. Therefore, the irregularities on the surface of the substrate 9 are the irregularities opposite to those of the stamper.

The guide groove of an optical disk is generally concentric,
Alternatively, it is formed in a spiral shape, and has a very fine structure with a track pitch of about 2 μm or less and a guide groove depth of about 100 nm or less. In injection molding, when resin is injected from the center of the disc,
As shown in (b), the resin flows from the inner peripheral side to the outer peripheral side of the substrate in a direction substantially perpendicular to the track direction, as shown by arrow 14, and fills the fine structure of the stamper.

[0007]

As shown in FIG. 3 (a), the guide groove of the optical disc is generally closer to the light input surface 10 of the substrate 9 than the light input surface of the substrate 9, and the guide groove portion 11, The far side is called the inter-groove portion 12. Therefore, as shown in FIG. 3B, in the stamper 15, the guide groove portion and the prepit are convex. In the conventional configuration, in the disc for groove recording, the pre-pit 3 such as the ID portion and the control track portion is used.
Is formed in the inter-groove portion 12 between the guide grooves and has a particularly fine structure, and when the resin flows in the injection molding, the adjacent guide grooves serve as a barrier in the pre-pit portion and its periphery. There is a problem that it is difficult to fill the resin.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a discontinuous guide groove portion adjacent to a prepit in an inter-groove portion.

[0009]

By applying the above-mentioned means, the resin easily flows into the prepit portion in the groove portion and its periphery by injection molding, and the stamper information is faithfully transferred to the substrate.

Further, by making the shapes of the pit row and the pre-pits in the track direction exactly the same or in opposite phases, it is possible to have pre-pits both in the groove and in the guide groove, and in both the groove and the guide groove. Information can be recorded, reproduced, and searched, and can be made very effective as position information when the recording density is doubled.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1A shows a schematic view of a groove structure of an optical disk substrate which is an embodiment of the present invention. In addition, FIG.
Used to make the substrate of FIG. 1 (a) in (a),
The schematic of the groove structure of a stamper is shown.

In FIG. 1A, 1a is a guide groove and 2a is a guide groove.
Is a space between grooves, 3a is a pre-pit, and 7 is a pit row of the guide groove 1a adjacent to the pre-pit 3a. See also FIG.
In (a), 1a 'is a guide groove forming portion of a stamper for forming a guide groove on a disc substrate, similarly 2a' is an inter-groove forming portion for forming a groove, and 3a 'is a prepit forming for forming a prepit. It is a department. Reference numeral 5 is a continuous groove area showing a range between the guide grooves, 6 is a pre-pit area showing a range of pre-pits, 7'is a pit row forming portion, and a discontinuous portion of the guide groove forming portion 1a 'in the pre-pit area. Indicates.

Information is recorded on the optical disk substrate,
A continuous guide groove to be reproduced or erased, an ID portion containing information such as a sector number and an address number following a region where there is a groove is connected to the groove 2a as a prepit 3a, and is adjacent to the prepit. The part of is the pit row 7.

In the stamper for molding the optical disk substrate, information is similarly recorded with the concave and convex portions reversed.
A prepit area 6 which is an ID portion containing information such as a sector number and an address number is provided next to the continuous groove area 5 where there are continuous grooves to be reproduced and erased, and the continuous groove area 5 where there is a space between grooves.
The groove forming portion a'is connected to the inter-groove forming portion 2a 'and adjacent to the pre-pit forming portion is formed by the pit row forming portion 7'.

In the injection molding for molding the optical disk substrate in FIG. 2A, the resin can flow between the pit row forming portions 7'in the direction of the arrow 4a and faithfully transfer the unevenness of the stamper to the substrate. Is possible. Although the guide groove in this portion in FIG. 1A is formed by the pit row 7, the output of the tracking error signal for causing the incident light beam for information recording / reproduction to follow the track is slightly reduced, but It can be made almost negligible by selecting the size. Further, in order to avoid the influence of the address or the like on the reproduction signal, it is desirable that the pit row 7 has a frequency different from that of the prepit 3 of the address or the like in the groove portion. 1 (a) and 2 (a), the pit row 7 has a finer structure than the pre-pit 3, and the pit row 7 has a higher reproduction frequency. It is also effective to make the pit train 7 longer than the length of the pit train so that the reproduced frequency is lower in the pit train 7. However, it is also possible to make the reproduction frequencies of the pit train 7 and the pre-pits substantially equal to each other if the difference in the reproduction amplitude due to the difference in the depth of the pit train 7 and the pre-pit 3 can be sufficiently secured.

It is also possible to make the pit row and the pre-pits have the same shape in the track direction or in the opposite phase for the above reason. In that case, in addition to the above-mentioned improvement of the pit transferability, the groove gap 2a Since it is possible to have pre-pits in both the groove and the guide groove 1a and address information can be configured in both the groove and the guide groove, it is possible to record, reproduce, and retrieve information in both the groove and the guide groove. It will be. Low interference between pre-pits and pit rows,
By selecting each depth pitch, it is possible to make the position information very effective when the recording density is doubled.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 1 (b) shows a schematic view of a groove structure of an optical disk substrate which is a second embodiment of the present invention. Also,
FIG. 2B shows a schematic view of the groove structure of the stamper used for manufacturing the substrate of FIG. 1B.

In FIG. 1B, 1b is a guide groove and 2b is a guide groove.
Is a space between grooves, 3b is a pre-pit, and 8 is a non-groove portion of the guide groove 1b adjacent to the pre-pit 3b. See also FIG.
In (b), 1b 'is a guide groove forming portion of a stamper for forming a guide groove on a disk substrate, similarly 2b' is an inter-groove forming portion for forming a groove, and 3b 'is a prepit forming a prepit. It is a department. Reference numeral 8'denotes a grooveless portion forming portion, which is the guide groove forming portion 1 in the prepit area.
The discontinuous part of b'is shown.

Information is recorded on the optical disk substrate,
A continuous guide groove to be reproduced and erased, and an ID portion containing information such as a sector number and an address number following the area where there is a groove is connected to the groove 2b as a prepit 3b, and is adjacent to the prepit. The portion without is a grooveless portion 8.

Similarly to the first embodiment, in the stamper, the concavities and convexities are reversed, and similarly, a continuous groove for recording, reproducing, and erasing information, a region where there is a space between the grooves, a sector number, an address number, etc. The ID portion containing information is connected to the inter-groove forming portion 2b 'as the pre-pit forming portion 3b',
The portion of the groove forming portion adjacent to the pre-pit forming portion is formed by the grooveless forming portion 8 '.

In injection molding for molding an optical disk substrate in FIG. 2 (b), since the portion adjacent to the pre-pit 3b has no guide groove like the grooveless discontinuous portion 8, the molten resin is directed in the direction of arrow 4b. It flows very smoothly and the unevenness of the stamper is faithfully transferred to the substrate. By eliminating the guide groove in the part adjacent to the pre-pit, tracking stability is slightly deteriorated, but since the length of the discontinuity without groove is short, the light beam can sufficiently follow the guide groove. The above is perfectly fine.

In addition, when the length of the grooveless discontinuity is long due to the disk structure and there is a problem in the light beam followability during recording / reproduction, the discontinuity corresponding to the grooveless discontinuity is completely removed. The guide groove depth should be λ
/ 8, it is also possible to provide a shallow guide groove within the range where the transferability does not deteriorate such that the depth of the grooveless discontinuous portion is set to about λ / 16.

Although the embodiment of the present invention has been described using the optical disk, it is obvious that the present invention is not limited to this and can be applied to the structure of a card-shaped or tape-shaped recording medium.

[0025]

As described above, by making the guide groove portion adjacent to the prepit in the groove portion discontinuous,
The resin easily flows into the pre-pit area in the groove and its surrounding area by injection molding, and the stamper information is faithfully transferred to the substrate. It is also very useful for narrowing the track pitch to achieve high density. It is an effective means and is extremely effective in practice.

Further, by making the shapes of the pit row and the prepits in the track direction exactly the same or in opposite phases, it becomes possible to have prepits both in the groove and in the guide groove, and in both the groove and the guide groove. Information can be recorded, reproduced, and searched, and can be made very effective as position information when the recording density is doubled.

[Brief description of drawings]

FIG. 1A is a schematic view of a groove structure of an optical disk substrate which is an embodiment of the present invention. FIG. 1B is a schematic view of a groove structure of an optical disk substrate which is an embodiment of the present invention.

2A is a schematic view showing a groove structure of a stamper for manufacturing the optical disk substrate of FIG. 1A, which is an embodiment of the present invention. FIG. 2B is an embodiment of the present invention. Schematic showing the groove structure of the stamper for producing the optical disk substrate of b)

3A is a schematic view showing a groove structure of a conventional optical disk substrate. FIG. 3B is a schematic view showing a groove structure of a stamper for manufacturing the conventional optical disk substrate shown in FIG. 3A.

[Explanation of symbols]

 1a Guide groove 1b Guide groove 2a Between grooves 2b Between grooves 3a Pre-pit 3b Pre-pit 4a Resin flowing direction 4b Resin flowing direction 5 Continuous groove area portion 6 Pre-pit area 7 Pit row 8 No groove discontinuity 9 Substrate 10 Light incident surface 15 Stamper

Claims (7)

[Claims] 1. Playback, recording, or erasing of information, on a plastic substrate having guide grooves and prepits,
A flat information recording medium having a reflective film or a recording medium and having prepits in at least some of the inter-groove portions, wherein guide groove portions adjacent to the prepit portions of the inter-groove portions are discontinuous. And a flat information recording carrier. 2. The flat information record carrier according to claim 1, wherein the discontinuous portion of the guide groove portion is a pit row. 3. The discontinuity portion of the guide groove portion is a pit row, and the position of the unevenness of the pit row and the length in the guide groove direction are substantially the same as those of the pre-pits. Flat record carrier. 4. The discontinuous portion of the guide groove portion is a pit row, and the position of the unevenness of the pit row and the length in the guide groove direction are in opposite phase to the pre-pit. Flat record carrier. 5. The flat information record carrier according to claim 1, wherein there is no guide groove or pit row in the discontinuous portion of the guide groove portion. 6. The flat information record carrier according to claim 1, wherein the depth of the guide groove at the discontinuous portion of the guide groove portion is shallower than the depth of the other guide groove portions. 7. Information is reproduced, recorded, or erased, and on a plastic substrate having guide grooves and prepits,
A stamper for a flat information recording carrier that forms a reflection film or a recording medium and has prepits in at least some of the inter-groove portions, and a guide groove portion adjacent to the prepit portion of the inter-groove portion of the flat record carrier. A stamper characterized in that the convex portions to be formed are discontinuous.