JPH07249238A - Discoid optical recording medium and production thereof - Google Patents

Abstract

PURPOSE:To provide a discoid optical recording medium with which the data transfer speed of about twice as fast as a data transfer speed at the time of performing a recording and reproducing from only the one-surface side of the discoid recording medium is obtainable when a simultaneous both-surface recording and reproducing is performed and in which substrate canters of two sheets consisting a disk substrate are made to be coincided with each other to be free from an eccentricity, and its production method. CONSTITUTION:In the production of the discoid optical recording medium in which two sheets of substrates 21, 22 in which recording tracks of a helical form or a concentric form are formed are stuck and recording or reproducings are performed simultanecously with respect to recording tracks of both main surfaces, reference marks 21b, 22b are formed at positions being out of recording areas of respective substrates. Then, two sheets of substrates are stuck while aligning positions in the peripheral directions of physical addresses with these reference marks and aligning substrate centers of two sheets of substrates to coincide with each other with second reference marks 21c, 22c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc-shaped optical recording medium such as an optical disc or a magneto-optical disc in which spiral or concentric recording tracks are formed on both main surfaces of a disc substrate, and a method for manufacturing the same. Particularly, it relates to improvement of data transfer rate.

[0002]

2. Description of the Related Art Discotic optical recording media such as optical discs and magneto-optical discs capable of optically recording and / or reproducing recorded information signals are made of transparent discotic synthetic resin materials or glass materials. A disc substrate is used, and a recording layer is formed on the disc substrate to record and / or reproduce information signals.

In recording and / or reproducing using the above-mentioned disc-shaped optical recording medium, it is desired to improve the data transfer rate.

By the way, in the disc-shaped optical recording medium, a recording layer for recording and / or reproducing is provided on both main surfaces of a single-sided optical recording medium in which only one main surface of the disk substrate is present. It is classified as a double-sided optical recording medium. Also,
The double-sided optical recording medium further includes a double-sided optical recording medium that performs recording and / or reproduction for each one main surface, and a double-sided optical recording medium that performs recording and / or reproduction simultaneously for both main surfaces. are categorized. The present invention relates to the latter double-sided optical recording medium. (In the following description, for convenience, one of the two main surfaces of the double-sided optical recording medium is referred to as “A
The main surface on the opposite side of the “surface” and the A surface is referred to as a “B surface”, and the A surface will be described as a reference. However, there is no difference between the A side and the B side, and the same applies when the B side is used as a reference. )

The double-sided optical recording medium can record about twice as much information as the single-sided optical recording medium, and can realize a large capacity. In general, a double-sided optical recording medium in which recording and / or reproducing is performed on both main surfaces at the same time, two substrates on which spiral recording tracks whose spiral directions are opposite to each other are formed are attached. It is manufactured together or by bonding two substrates on which concentric recording tracks are formed.

Recording and / or recording using the double-sided optical recording medium
Alternatively, in reproduction, as one means for improving the data transfer rate, two heads symmetrically positioned with the double-sided optical recording medium sandwiched are used to simultaneously record and / or record on both main surfaces of the double-sided optical recording medium. A multi-head system for reproducing is under study. As a result, it can be expected that the data transfer rate will be about twice as high as that when recording and / or reproducing is performed from only one side. (Hereinafter, the above recording and / or reproduction will be referred to as “simultaneous double-sided recording / reproduction”.)

When recording data in the double-sided simultaneous recording / reproducing, first, the data is divided into two. Then, one of the divided data is recorded on the recording track of the A side, and the other one of the divided data is recorded on the recording track of the B side. At this time, the head on the B side waits for a physical address on the B side that is the same as the physical address on the A side on which one of the data is recorded, and when this physical address comes, the data divided into the physical addresses Record the other one. This is because the other side of the data is recorded at the same physical address of the A side where the one side of the data is recorded and the same physical address of the B side.

In the double-sided simultaneous recording / reproduction, when the data is reproduced, since the data is divided and recorded on the A side and the B side, the data recorded at the physical address on the A side is reproduced. At the same time, the data recorded at the physical address on the same side B as the physical address is reproduced. At this time, the head on the B side reproduces the data A
It waits for the physical address of the same side B as the physical address of the side to come, and when this physical address comes, the other one of the divided data is reproduced. Then, the data from the A side and the data from the B side are combined to reproduce the data before division.

In the double-sided simultaneous recording / reproducing as described above, B recording is performed between the recording / reproducing of data at a physical address on the A side and the recording / reproducing of data at a physical address on the B side which is the same as the physical address. A rotation waiting time is required until the same physical address of the A side as the physical address of the A side arrives at the head on the side of the surface. The rotation waiting time is the rotation waiting time for rotating the disc-shaped optical recording medium about one rotation at maximum.

When the above-mentioned rotation waiting time occurs, the data transfer rate does not improve much even if double-sided simultaneous recording / reproducing is performed. In some cases, it is better to perform recording / reproducing only from one side of the disc-shaped optical recording medium. Transfer speed becomes faster.

For example, for a disc-shaped optical recording medium capable of recording 10 kilobytes of data with 17 sectors per recording track and recording 1 kilobyte of data in one sector,
Consider a case where recording / reproducing is performed by a recording / reproducing apparatus having a medium rotation speed of 1800 rpm.

At this time, it takes about 19.6 milliseconds to record / reproduce only from one side. That is, the data transfer rate is about 510 kilobytes / second. On the other hand, in double-sided simultaneous recording / reproduction, when recording / reproducing 5 kilobytes of data on each of the A side and B side, if the physical address of the A side and the physical address of the B side are the same, from one side It is about 9.8 times, which is half the time required for recording and reproducing.
It only takes milliseconds. That is, the data transfer rate is about 1020 kilobytes / second. However, when the position of the physical address of the A side and the physical address of the B side, where the rotation waiting time is the maximum, is deviated by about one rotation of the disk, the rotation waiting time requires about 33.3 milliseconds. About 43.1
It takes milliseconds (9.8 milliseconds +33.3 milliseconds). That is, the data transfer rate is about 232 kilobytes / second.

As described above, the data transfer rate is about 510 kilobytes / second when recording / reproducing is performed only from one side, whereas the data transfer rate is about 232-1020 kilobytes / second in double-sided simultaneous recording / reproducing.

[0014]

A conventional double-sided optical recording medium is manufactured by bonding two substrates together as described above. Therefore, it is difficult to match the positions of the physical addresses physically formed on the recording track on the A side and the B side, and the positions of the physical addresses are displaced in the circumferential direction on the A side and the B side. Will end up. For this reason, the above-described rotation waiting time occurs, and even if double-sided simultaneous recording / reproducing is not performed, a stable improvement in data transfer rate cannot be expected. In some cases, recording / reproducing is performed only from one side of the disc-shaped optical recording medium. The data transfer speed will be faster if you do it. In particular, in recording / reproducing of data having a small capacity, for example, recording / reproducing of data of a size that can be recorded on two tracks or less, the ratio of the rotation waiting time to the time required for recording / reproducing of data becomes large, and the data transfer rate is increased. Is easy to slow down.

When the two substrates are bonded together,
The substrate centers of the two substrates may be displaced. If this center shift occurs, when the hub or inner diameter hole on one main surface of the double-sided optical recording medium is chucked and rotated to perform double-sided simultaneous recording / reproduction, the surface on the chucked side is normal. However, recording and reproducing cannot be performed normally because eccentricity occurs on the other surface.

Therefore, the present invention has been proposed in view of such a conventional situation, and the rotation waiting time does not occur even when the double-sided simultaneous recording / reproducing is performed, and the disk-shaped optical recording medium is viewed from one side. An object of the present invention is to provide a disc-shaped optical recording medium and a method for manufacturing the same, which can obtain a data transfer rate that is about twice the data transfer rate when recording / reproducing is performed only. Furthermore,
A disc-shaped optical recording medium and a method for manufacturing the same, in which the substrate centers of two substrates constituting the disc-shaped optical recording medium are coincident with each other, and the double-sided simultaneous recording / reproducing can be performed normally without causing eccentricity even when the double-sided simultaneous recording / reproducing is performed. It is also intended to be provided.

[0017]

In order to achieve the above object, the disk-shaped optical recording medium of the present invention has spiral recording tracks or concentric recording tracks formed on both main surfaces of a disk substrate. In the disk-shaped optical recording medium in which recording and / or reproduction are simultaneously performed on the recording tracks on the both main surfaces, the positions of physical addresses physically formed on the both main surfaces are substantially equal to each other in the circumferential direction. It is a match.

The disc-shaped optical recording medium is a disc substrate in which two disc substrates are bonded together, and reference marks for aligning physical addresses with each other in the circumferential direction at positions deviated from the recording area of each substrate. May be formed. Alternatively, the disc substrate is a disc substrate in which two substrates are bonded together, and a second substrate for aligning the substrate centers with each other at a position deviated from the recording area of each substrate.
The reference mark may be formed. The two types of reference marks may be formed on one side or both sides.

On the other hand, according to the manufacturing method of the present invention, the spiral recording tracks are formed in which the spiral directions are opposite to each other.
A method for manufacturing a disc-shaped optical recording medium, in which two substrates are bonded together, or two substrates having concentric recording tracks are bonded together, and recording and / or reproduction are simultaneously performed on the recording tracks on both main surfaces. Therefore, a reference mark is formed at a position off the recording area of each substrate, and the two substrates are bonded while aligning the positions of the physical addresses in the circumferential direction with the reference mark.

In the above manufacturing method, the positions of the physical addresses in the circumferential direction are aligned by the reference mark, and the two substrates are bonded while the substrate centers of the two substrates are aligned with each other by the second reference mark. It is preferable.

The reference mark and the second reference mark may be any marks as long as they can be identified by a sensor using a CCD camera or the like. For example, a physical mark in which unevenness is provided on a part of the substrate. Alternatively, it is possible to use an optical mark or the like in which a portion having a reflectance and a transmittance different from those of the surroundings is provided on a part of the substrate.

The two substrates are bonded to each other with an adhesive such as hot melt, double-sided adhesive tape, or ultraviolet curable resin.

The recording medium to which the present invention can be applied is not particularly limited as long as it is a double-sided optical recording medium, and it can be applied to a magneto-optical disc, a write-once optical disc, a phase change type rewritable optical disc and the like. Further, the format is not particularly limited as long as it is the same format on both main surfaces, and may be a rotation mode such as constant angular velocity or constant linear velocity, or even constant angular velocity for each zone. .

[0024]

When the double-sided simultaneous recording / reproduction is performed using the disc-shaped optical recording medium in which the positions of the physical addresses physically formed on both main surfaces of the disk substrate are substantially the same in the circumferential direction, the rotation described above is performed. There is no waiting time.

Further, the disc substrate is a disc substrate obtained by laminating two substrates, and a disc-shaped optical recording medium in which the substrate centers of the two substrates are aligned is used, and one of the main surfaces of the disc substrate is When double-sided simultaneous recording / reproduction is performed by chucking and rotating the hub or the hole having the inner diameter, eccentricity does not occur on either the chucked side or the unchucked main surface.

When two substrates are bonded together to form a disk substrate, reference marks for aligning physical addresses physically formed on both main surfaces of the disk substrate with each other in the circumferential direction are provided on each substrate. By forming
It is possible to easily bond the two substrates by matching the positions of the physical addresses on the A side and the B side in the circumferential direction.

When the two substrates are bonded to each other to form a disk substrate, a second reference mark for aligning the substrate centers of the two substrates with each other is formed on each substrate to facilitate the operation. Two substrates can be bonded to each other with the substrate centers of the substrates aligned.

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 The disc-shaped optical recording medium of this example is a double-sided optical recording medium, and is manufactured by bonding two substrates 1 and 2. FIG. 1 shows the step of this bonding.

The substrate 1 has an opening 1a at the center,
A spiral recording track is formed on one main surface,
A physical address is physically formed. The first reference mark 1b for aligning the physical addresses of the two substrates with each other in the circumferential direction is on the line from the physical address serving as the reference (for example, the address of 0 sector) toward the substrate center. It is provided in an area that is not used for recording / reproduction between the recording area and the center of the substrate.

Further, the substrate 2 has an opening 2a in the central portion thereof, and a spiral recording track in a direction opposite to the spiral direction of the recording track of the substrate 1 is formed on one main surface and is physically physically formed. An address is formed. The first reference mark 2b for aligning the physical addresses of the two substrates with each other in the circumferential direction is at the same position as the first reference mark 1b provided on the substrate 1, that is, the substrate 1
It is provided in an area which is not used for recording / reproduction between the recording area of the substrate and the substrate center on the line extending from the same physical address as the reference to the center of the substrate.

Of the two main surfaces of the substrates 1 and 2,
The main surface on the side where the optical head for recording / reproducing is located is referred to as a "recording / reproducing surface", and the other main surface is referred to as an "adhesion surface".

The device for bonding these two substrates 1 and 2 mainly comprises a CCD camera 3 for recognizing the first reference mark 1b on the substrate 1 and a first reference mark 2 on the substrate 2.
CCD camera 4 for recognizing b and two substrates 1,
A disc-shaped support 5 for supporting the substrates 1 and 2 when the substrates 2 are bonded together, and a substrate holding jig 6 for supporting the substrate 2 on the support 5.

The CCD cameras 3 and 4 are used as sensors for recognizing the first reference marks 1b and 2b, and the CCD camera 3 and 4 correspond to the distance between the center of the substrate and the first reference marks. These two Cs are located off center.
The CCD camera 3 is positioned below the support base 5 and the second CCD camera 4 is positioned above the support base 5 symmetrically across the support base 5 so that the optical axes m1 of the CD cameras 3 and 4 coincide with each other. It is arranged to do.

The support base 5 is transparent at least in a portion corresponding to the recognition area of the CCD camera 3 so that the CCD camera 3 can recognize the substrate 1 placed on the support base 5 through the support base 5. . A center pin 5a is provided at the center of the support base 5. The center pin 5a is a protrusion provided at the center of the support base 5,
By inserting the center pin 5a into the openings 1a and 2a in the central portions of the two substrates 1 and 2, the substrate centers of the two substrates 1 and 2 are aligned.

The substrate holding jig 6 can support the substrate 2 on the support 5 and can rotate the substrate 2 and lower the substrate 2 on the support 5.

When the two substrates 1 and 2 are attached to each other using the above apparatus, first, an adhesive is applied to the adhesive surface of the substrate 1. Then, with the substrate 1 with the recording / reproducing surface facing down,
The support 5 is placed so that the center pin 5a is inserted into the opening 1a in the central portion. Then, the substrate 1 is rotated while being observed by the CCD camera 3 so that the first reference mark 1b of the substrate 1 is on the optical axis m1 of the CCD camera 3.

Next, the substrate 2 is supported by the substrate holding jig 6 on the support base 5 so that the center pin 5a is inserted into the opening 2a at the center when the substrate 2 is lowered with the adhesive surface. To do. Then, the substrate 2 is rotated while being observed by the CCD camera 4, and the first reference mark 2b of the substrate 2 is the CCD.
It should be on the optical axis m1 of the camera 4. After that, the substrate 2 is lowered onto the support 5 and the substrate 1 and the substrate 2 are bonded together.

As a result, the first fiducial marks 1b, 2b
The two substrates 1 and 2 are attached to each other after the positions of 1 and 2 match. The first reference marks 1b and 2b may be matched within a range of about ± 2 mm.

In this way, a disk-shaped optical recording medium is formed in which the positions of the physical addresses physically formed on both main surfaces are the same in the circumferential direction.

Any reference mark may be used as long as it can be identified by a sensor. For example, a physical mark having unevenness on a part of the substrate, a reflectance on a part of the substrate, An optical mark provided with a portion having a transmittance different from that of the surrounding area can be used.

In order to easily identify the optical mark with a sensor, it is preferable that the difference in reflectance or transmittance between the optical mark and its peripheral portion is 10% or more. In order to form such an optical mark, for example, when a recording film, a reflective film, or the like is coated on the substrate, only the portion where the optical mark is desired to be formed is not coated, or
Alternatively, a coating different from other portions may be formed only on the portion where the optical mark is to be formed.

The shape of the reference mark is not particularly limited as long as it can be recognized by the sensor, and may be, for example, a line, a pit, a lattice, a triangle, or the like. And the size should just be a size that can be recognized by the sensor, and specifically, 0.3 mm to 3 m.
A width and length of m, preferably a size such that it is formed in a region having a width and length of 1 to 2 mm.

2 and 3 show examples of linear physical marks. FIG. 2 is an enlarged top plan view of a mark forming portion of a disc-shaped optical recording medium on which linear physical marks are formed. FIG. 3 is a cross-sectional perspective view of the physical mark taken along the line AB. This physical mark 12 has a plurality of parallel line-shaped grooves at the position deviated from the recording area 11 when forming a groove which is a guide groove, like the groove.
It is formed in a region having a size as described above. Since the physical mark 12 is formed together with the groove, it is formed on the same surface as the surface on which the groove is formed.

FIG. 4 and FIG. 5 show examples of pit-shaped physical marks. FIG. 4 is an enlarged top plan view of a mark forming portion of a disc-shaped optical recording medium on which pit-like physical marks are formed. FIG. 5 is a sectional perspective view of the physical mark taken along the line C-D. When forming a pit for indicating information such as a physical address, the physical mark 13 has a plurality of pit-shaped elliptical holes at the position deviated from the recording area 11 in the same manner as the above-mentioned pit. It is formed in a region having a size of. Since the physical mark 13 is formed together with the pit, it is formed on the same surface as the surface on which the pit is formed.

FIG. 6 and FIG. 7 show an example of a grid-like physical mark. FIG. 6 is an enlarged top plan view of a mark forming portion of a disc-shaped optical recording medium on which lattice-like physical marks are formed. FIG. 7 is a sectional perspective view of the physical mark taken along the line EF. The physical mark 14 is formed by forming a grid-like groove at a position deviated from the recording area 11 in an area having a size as described above. The physical mark 14 is formed, for example, by forming a lattice-shaped unevenness on the stamper in advance and then molding the substrate. Alternatively, it is formed by molding a substrate and then stamping it with a metal or the like having a grid-like unevenness. When the stamper is provided with irregularities in advance, it is formed on the surface in contact with the stamper, that is, on the same surface as the surface on which the grooves, the pits, and the like are formed. On the other hand, in the case where the substrate is formed by stamping unevenness after molding, it may be formed on either surface.

Example 2 The disk-shaped optical recording medium of this example is a double-sided optical recording medium and is manufactured by bonding two substrates 21 and 22 together. FIG. 8 shows this bonding process.

The substrate 21 has an opening 21a in the center, a spiral recording track is formed on one main surface, and a physical address is physically formed. And
Similar to the first embodiment, the first reference mark 21b for aligning the physical addresses of the two substrates with each other in the circumferential direction is directed from the reference physical address (for example, 0 sector address) toward the substrate center. It is provided in the area on the line between the recording area of the substrate and the center of the substrate, which is not used for recording and reproduction. Then, further, the two substrates 21, 2
A second reference mark 21c for aligning the two substrate centers with each other is provided in a circular shape centered on the substrate center in a region between the substrate recording region and the substrate center that is not used for recording and reproduction. Has been.

The substrate 22 has an opening 22 at the center.
a, a spiral recording track in a direction opposite to the spiral direction of the recording track of the substrate 21 is formed on one main surface, and a physical address is physically formed. And
Similar to the first embodiment, the first reference mark 22b for aligning the physical addresses of the two substrates 21 and 22 with each other in the circumferential direction is similar to the first reference mark 21a provided on the substrate 21. It is provided at a position, that is, on a line from the same physical address as the reference physical address on the substrate 21 toward the substrate center and between the recording region of the substrate 22 and the substrate center that is not used for recording and reproduction. . Further, the second reference mark 22c for aligning the substrate centers of the two substrates 21 and 22 with each other is at the same position as the second reference mark 21c provided on the substrate 21, that is, the substrate center. In a circular shape centered on
Is provided in an area that is not used for recording / reproducing between the recording area and the substrate center.

Of the two main surfaces of the substrates 21 and 22, the main surface on the side where the optical head for recording / reproducing is located is the "recording / reproducing surface", and the other main surface is the "adhesive surface". To call.

The device for bonding these two substrates 21 and 22 mainly recognizes the CCD camera 23 for recognizing the first reference mark 21b of the substrate 21 and the first reference mark 22b of the substrate 22. CCD camera 24 for
A CCD camera 27 for recognizing the second reference mark 21c on the substrate 21, and the second reference mark 2 on the substrate 22.
A CCD camera 28 for recognizing 2c, a disk-shaped support 25 for supporting the substrate 22 when the two substrates 21 and 22 are bonded together, and a substrate 22 on the support 25 for supporting the substrate 22. It comprises a substrate holding jig 26.

The CCD cameras 23 and 24 are used as sensors for recognizing the first reference marks 21b and 22b, and the center of the support base 25 is the distance between the center of the substrate and the first reference marks. These two are in a position away from
The CCD cameras 23 are positioned below the support base and the CCD cameras 24 are positioned above the support base 25 symmetrically with the support base 5 interposed therebetween so that the optical axes m2 of the CCD cameras 23 and 24 of the bases coincide with each other. It is installed in.

The CCD cameras 27, 28 are used as sensors for recognizing the second fiducial marks 21c, 22c, and the center of the support base 25 is the distance between the center of the substrate and the second fiducial marks. The support base 25 is placed so that the optical axes m3 of the two CCD cameras 27 and 28 coincide with each other at a position deviated from the position and symmetrical with the CCD cameras 23 and 24 via the center of the support base 25. Symmetrically, the CCD camera 27 is disposed below the support base 25, and the CCD camera 28 is disposed above the support base 25 symmetrically. In addition, these two CCD cameras 27, 28
Allows a slight translation in the radial direction of the support base 25.

The support 25 is the substrate 21 on which the CCD camera 23 is placed on the support 25 through the support 25.
At least a portion corresponding to the recognition area of the CCD camera 23 is transparent so that can be recognized. A center pin 25a is provided at the center of the support table 25. The center pin 25a is a protrusion provided in the central portion of the support base 25. By inserting the center pin 25a into the openings 21a and 22a in the central portions of the two substrates 21 and 22, the two substrate 21 , 22 are aligned with the center of the substrate.

The substrate holding jig 26 can support the substrate 22 on the support base 25, and
The substrate 22 can be rotated or the substrate 22 can be lowered onto the support base 25.

When the two substrates 21 and 22 are attached to each other using the above apparatus, first, an adhesive is applied to the adhesive surface of the substrate 21. Then, with the recording / reproducing surface facing down, the substrate 21 is inserted into the center pin 25a in the opening 21a in the central portion.
Is placed on the support base 25 so that Then, the substrate 21 is rotated while observing with the CCD camera 23,
The first reference mark 21b on the substrate 21 is the CCD camera 2
It should be on the optical axis m2 of 3. Then, the CCD cameras 27, 28 are moved in parallel in the radial direction of the support base 25 so that one point on the second reference mark 21c of the substrate 21 is on the optical axis m3 of the CCD cameras 27, 28.

Next, the substrate 22 is supported on the support base 25 by the substrate holding jig 26 so that the center pin 25a is inserted into the opening 22a at the center when the substrate 22 is lowered with the adhesive surface. To do. Then, the substrate 22 is translated and rotated while observing with the CCD cameras 24 and 28 so that the first fiducial mark 22b of the substrate 22 is on the optical axis m2 of the CCD camera 24 and the substrate 22. A point on the second reference mark 22c of is located on the optical axis m3 of the CCD camera 28. After that, the substrate 22 is lowered onto the support 25, and the substrate 21 and the substrate 22 are bonded together.

As a result, the first fiducial marks 21b, 2
When the positions of 2 are aligned, the second reference mark 21
After the positions of c and 22c are aligned, the two substrates 21 and 2 are
2 are pasted together. The center of the two substrates 21 and 22 is aligned with each other by inserting the center pin 25a into the openings 21a and 22a at the center of the two substrates 21 and 22, but this is accurate. It is difficult to match the second reference marks 21c and 22c.
By using, it is possible to match more accurately.

In this way, the positions of the physical addresses physically formed on both main surfaces coincide with each other in the circumferential direction, and
A disc-shaped optical recording medium in which the substrate centers of the two substrates are aligned is constructed.

In this embodiment, the second fiducial mark is a circular mark, and the first fiducial mark and one point on the circular mark are used to align the positions of the substrate centers of the two substrates. However, the second fiducial mark may be any mark as long as it can match the positions of the substrate centers of the two substrates. For example, the second fiducial mark can be a dot-shaped mark at a position different from that of the first fiducial mark. A mark may be provided, and the positions of the substrate centers of the two substrates may be aligned with each other using the first reference mark and this dot-shaped mark. Alternatively, by providing a plurality of dot-shaped marks at different positions and using these dot-shaped marks,
The positions of the substrate centers of the two substrates may be aligned.

When recording data on both major surfaces of the disk-shaped optical recording medium of the above-mentioned first and second embodiments, first, the data is divided into two. Then, one of the divided data is recorded on the recording track 14 of the A side, and the other one of the divided data is recorded on the recording track 15 of the B side.
The recording on the A side and the recording on the B side are recorded at the same physical address. At this time, the positions of the physical address on the A side and the physical address on the B side are the same, so that they can be recorded at the same time.

When data is reproduced from both main surfaces of the disc-shaped optical recording medium, since the data is recorded separately on the A side and the B side, it is recorded at a physical address on the A side. In addition to reproducing the data, the data recorded at the same physical address on the B side as the physical address is reproduced. At this time, since the positions of the physical address on the A side and the physical address on the B side are the same, they can be reproduced at the same time.

In the double-sided simultaneous recording / reproducing as described above, since the positions of the physical addresses on the A side and the B side match, it is possible to record / reproduce on both sides simultaneously.
That is, between the recording / reproducing of data at the physical address of the A side and the recording / reproducing of data at the same physical address of the B side as the physical address, the head on the B side has the same physical address as the A side. Until the physical address of the B side of
No rotation waiting time is required. Therefore, since the rotation waiting time does not occur, the data transfer speed becomes about twice as high as that in the case where the recording / reproducing is performed only from one side by one head.

For example, in a disk-shaped optical recording medium capable of recording 10 kilobytes of data with 17 sectors per recording track and recording 1 kilobyte of data in one sector, a recording / reproducing apparatus having a medium rotation speed of 1800 rpm, Consider the case of recording and reproducing.

At this time, it takes about 19.6 milliseconds when recording and reproducing from only one side. That is, the data transfer rate is about 510 kilobytes / second. On the other hand, in double-sided simultaneous recording / reproduction using the disc-shaped optical recording medium of the present embodiment, A
When recording / reproducing 5 kilobytes of data on each of side A and side B, the physical address of side A and the physical address of side B match, so half the time required for recording / reproducing from only one side. It takes about 9.8 milliseconds. In other words, about twice as much as when recording and reproducing from only one side,
A data transfer rate of approximately 1020 kilobytes / second is obtained.

When the disk-shaped optical recording medium of Example 2 is used to perform simultaneous double-sided recording / reproduction by chucking and rotating the hub or inner diameter hole on one main surface of the disk substrate. Since the substrate centers of the two substrates forming the substrate are aligned, eccentricity does not occur on the principal surface of either the chucked side or the unchucked side, and normal double-sided simultaneous recording is possible. Can be played.

[0067]

As is apparent from the above description, by using the disc-shaped optical recording medium in which the positions of the physical addresses physically formed on both main surfaces of the disk substrate are substantially the same in the circumferential direction, When double-sided simultaneous recording / reproduction is performed, the above rotation waiting time does not occur. Therefore, a double-sided simultaneous recording / reproducing can obtain a data transfer rate about twice as high as the data transfer rate when recording / reproducing is performed only from one side of the disc-shaped optical recording medium.

Further, since the above rotation waiting time does not occur, a buffer memory for temporarily storing the data divided into two is unnecessary during this rotation waiting time. Therefore, it is possible to reduce the size of the device used for double-sided simultaneous recording / reproduction and reduce the production cost thereof.

Further, by using a disc-shaped optical recording medium in which the substrate centers of the two substrates constituting the disk substrate are aligned,
When the hub on one main surface of the disk substrate or the hole of the inner diameter is chucked and rotated to perform double-sided simultaneous recording / reproduction, on both the chucked side and the non-chucked side, the main surface, No eccentricity occurs. Therefore, simultaneous double-sided recording / reproducing can be normally performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of one step of a method for manufacturing a disc-shaped optical recording medium of the present invention.

FIG. 2 is a top plan view showing an example of a reference mark applied to the present invention.

3 is a cross-sectional perspective view of the reference mark shown in FIG. 2 taken along the line AB.

FIG. 4 is a top plan view showing another example of the reference mark applied to the present invention.

5 is a cross-sectional perspective view of the reference mark shown in FIG. 4 taken along the line C-D.

FIG. 6 is a top plan view showing another example of the reference mark applied to the present invention.

7 is a sectional perspective view of the reference mark shown in FIG. 6 taken along the line EF.

FIG. 8 is a perspective view showing another example of one step of the method for producing a disc-shaped optical recording medium of the present invention.

[Explanation of symbols]

 1, 2, 21, 22 Substrate 1b, 2b, 21b, 22b First fiducial mark 21c, 22c Second fiducial mark 3, 4, 23, 24, 27, 28 CCD camera 5, 25 Support base 6, 26 Substrate Hold jig 11 Recording area 12, 13, 14 Physical mark

Claims (5)

[Claims] 1. A disc-shaped recording medium having spiral recording tracks or concentric recording tracks formed on both main surfaces of a disk substrate, and recording and / or reproducing being performed simultaneously on the recording tracks on the both main surfaces. In the optical recording medium, the positions of the physical addresses physically formed on the both main surfaces are substantially the same in the circumferential direction, and the disc-shaped optical recording medium. 2. The disk substrate is a disk substrate obtained by bonding two substrates together, and a reference mark for aligning physical addresses with each other in the circumferential direction is formed at a position deviated from the recording area of each substrate. The disc-shaped optical recording medium according to claim 1, wherein 3. The disk substrate is a disk substrate in which two substrates are bonded together, and a reference mark for aligning the substrate centers with each other is formed at a position deviated from the recording area of each substrate. The disc-shaped optical recording medium according to claim 1 or 2. 4. The two main surfaces are bonded together by bonding two substrates having spiral recording tracks formed with spiral directions opposite to each other or two substrates having concentric recording tracks bonded together. When manufacturing a disk-shaped optical recording medium that simultaneously records and / or reproduces on the recording tracks of, the reference mark is formed at a position deviated from the recording area of each substrate, and the position of the physical address in the circumferential direction is formed by these reference marks. A method for manufacturing a disc-shaped optical recording medium, characterized in that two substrates are bonded together while aligning. 5. A reference mark is used to align the positions of the physical addresses in the circumferential direction, and the second reference mark is used to bond the two substrates while aligning the substrate centers of the two substrates with each other. The method for producing a disc-shaped optical recording medium according to claim 4.