JPH11339318A - Disk shape information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk shape recording medium having ROM and RAM permitting to be manufactured at a low cost by cementing a 1st substrate of ROM where a reflecting film is deposited on a rugged region with recorded information and a 2nd substrate of RAM where a recording film is deposited on the region of recorded grooves with a light-transmissive adhesive. SOLUTION: This disk shape information recording medium 10 is comprised of a 1st substrate 12, a 2nd substrate 14, and an intermediate light-transmissive adhesive 16. The 1st substrate 12 is a read only memory formed by depositing a reflecting film on a rugged region with recorded information. This disk shape information recording medium 10 has a center hole 18 at the center part. The 1st substrate 12 has a disk shape substrate part 20, information pits 22, and a reflecting film 24. The substrate part 20 of the 1st substrate 12 is made of, for example, plastics like light-transmissive polycarbonate. The 2nd substrate 14 has a substrate part 30, recording grooves 32, and a recording film 34. The substrate part 30 is made of, for example, polycarbonate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc-shaped information recording medium formed by laminating substrates.

[0002]

2. Description of the Related Art In general, a disk-shaped information recording medium has attracted attention for recording audio signals, image information, and the like. This disc-shaped information recording medium is a so-called ROM (read / write) that only reproduces a signal called, for example, a video disc or a compact disc (trade name).
There is an information recording medium of the "only memory" type or a write-once type information recording medium such as a so-called WO (write once disk). Further, examples of the disc-shaped information recording medium include an optical disc-shaped rewritable information recording medium and a magneto-optical disc. In a write-once disk, a rewritable optical disk, a magneto-optical disk, or the like, reading and recording of information can be performed by irradiating a laser beam.

[0003] By the way, such a disc-shaped information recording medium has a ROM (read only memory, read only memory) area and a RAM on a single substrate.
There is a hybrid-type disc-shaped information recording medium having an area of (random access memory, random write / read memory).

FIG. 3 shows the structure of such a hybrid type information recording medium 110, in which one substrate 100
On the top, a ROM area 101 and a RAM area 102
Are formed. The ROM 101 is located on the inner peripheral side of the substrate 100, and the RAM area is located on the outer peripheral side of the substrate 100. In the disk-shaped substrate 100 thus integrally formed, the reflective film 104 is formed in the area of the pit 103 of the ROM area 101, and at the same time, the recording film 106 is formed in the recording groove 105 of the RAM area 102. There is a need. In order to form the integrally molded substrate 100 as shown in FIG. 3, a molding master 107 as shown in FIG.
is necessary. A ROM area 108 is formed in an inner peripheral area of the molding master 107, and a RAM area 109 is formed in an outer peripheral area.

[0005]

However, a disc-shaped hybrid information recording medium 110 shown in FIG.
The molding master 107 for that purpose shown in FIG. 4 has the following problems. As in the case of a molding master 107 shown in FIG.
If the area 109 needs to be formed simultaneously, the pits 103 and the recording groove 105 have different groove depths and groove widths, so that it is difficult to form the pits 103 and 100% satisfactorily. Since the RAM area 109 does not contain any content,
It is possible to press more than ten thousand information recording media for the RAM area. However, the ROM area 108 contains contents, and depending on the contents, only about 1,000 sheets can be pressed.
Since it is necessary to recreate the
When the OM area 108 and the RAM area 109 are formed at the same time, the production cost of the master 107 increases.

In the information recording medium 110 shown in FIG. 3, the pits 103 in the ROM area 101 and the RA
Since the groove shape of the recording groove 105 in the M area 102 is greatly different, it is difficult to perform optimum molding at the same time.
For example, the depth of the pit in the ROM area is ４λ, and the depth of the groove in the RAM area is ６λ. Forming the recording groove 105 and forming the recording film 106 in the RAM area 102 requires twice to five times as long as forming the pit 103 and forming the reflective film 104 in the ROM area. For example, the optimum molding conditions for the ROM and the RAM differ from each other. The ROM molding temperature is 90 to 100 ° C., while the RAM molding temperature is 120 to 130 ° C. For this reason, it is difficult to manufacture such a hybrid information recording medium 110. Depending on the contents of the ROM area 101, the contents of the original ROM area 108 need to be changed. On the other hand, since the RAM area 109 does not include the contents, the RAM area 109 does not need to be changed. In other words, the ROM area 108 must be recreated when the contents are changed, but the RAM area 109 does not include the contents, and can be stored.

[0007] Therefore, if the ROM area 101 and the RAM area 102 are formed simultaneously on the same substrate 100, there is a problem in actual production, and the manufacturing cost increases. Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a disk-shaped information recording medium having a read-only memory and a random access memory which can be manufactured at low cost.

[0008]

According to the present invention, there is provided a first substrate of a read-only memory in which a reflection film is formed on an uneven area in which information is recorded in advance, and a recording groove area. Second of random access memory with recording film
By bonding the substrate and the light-transmitting adhesive,
Achieved.

According to the present invention, the lead-only circuit of the first substrate is provided.
In the memory, a reflective film is formed in an uneven area in which information is recorded in advance. The random access memory on the second board is
The recording film is formed in the recording groove area. The first substrate and the second substrate are bonded with a light-transmitting adhesive. Thus, a read-only memory of the first substrate, which is likely to be changed due to the change of the content, and a random access memory of the second substrate, which can be used regardless of the change of the content, are separately prepared. By adhering with a light-transmitting adhesive, a hybrid disk-shaped information recording medium can be obtained at low cost.

In the present invention, preferably, the second substrate has a light transmitting property, and the second substrate for reading the information of the first substrate.
By irradiating light to the uneven region side through the substrate and the adhesive, and irradiating the light through the second substrate, information can be written to the second substrate or information can be read from the second substrate. In the present invention, preferably, the adhesive is a transparent ultraviolet curable resin.

[0011]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIG. 1 shows a preferred embodiment of a disc-shaped information recording medium 10 according to the present invention. The disc-shaped information recording medium 10 has a sectional structure as shown in FIG. The disc-shaped information recording medium 10 includes a first substrate 12, a second substrate 14, and an intermediate light-transmitting adhesive layer (adhesive) 16. First substrate 12
Is a read-only memory in which a reflective film is formed in an uneven area in which information is recorded in advance. The second substrate 14 is a random access memory in which a recording film is formed in a recording groove area. This disc-shaped information recording medium 10 has a center hole 18 at the center, and a half area of the disc-shaped information recording medium 10 of FIG. 1 is shown in cross section in FIG.

The first substrate 12 has a disk-shaped substrate portion 2.
0, information pits (irregularities) 22 and a reflective film 24. The substrate portion 20 of the first substrate 12 is made of, for example, plastic such as polycarbonate having optical transparency. The information pits 22 are formed on the inner side of the substrate portion 20. Such information pits 22 can be made from a master for creating information pits. On the information pits 22, a thin reflective film 24 is formed. The reflective film 24 can be made of a material having excellent light reflection characteristics, such as aluminum. The information pits 22 and the reflection film 24 are formed, for example, from the center in the radial direction to the inner peripheral side of the disc-shaped information recording medium 10. On the other hand, the second substrate 14 is
0, a recording groove (recording portion groove) 32, and a recording film 34. The substrate portion 30 is made of, for example, plastic such as polycarbonate having optical transparency.
A recording groove 32 is formed on the inner surface side of the substrate portion 30, and a recording film 34 is thinly formed on the recording groove 32.

The recording groove 32 can be formed using a master for forming the recording groove 32. This recording groove 32
And a master for forming the above-described information pits 22 are separate masters. The recording film 34 is formed in the recording groove 32, and is made of SiO ₂ , ZnS, SbA.
A multilayer film such as gAb, ZnS, or highly reflective aluminum can be employed. In the example of FIG. 2, the thickness W of the substrate portion 30 is, for example, 0.6 mm, and the thickness W1 obtained by adding the thickness of the light-transmitting adhesive layer 16 and the thickness W of the substrate portion 30 is obtained.
Is, for example, 0.60 mm ± 0.03 mm. The thickness W2 of the substrate portion 20 is, for example, 0.6 mm. The recording groove 32 and the recording film 34 are formed, for example, from the central portion to the outer peripheral portion of the disc-shaped information recording medium 10. For this reason, preferably, the information pits 22 and the reflective film 24 of the first substrate 12 and the recording grooves 32 and the recording film 34 of the second substrate 14 are formed so as not to overlap. As the light-transmitting adhesive layer 16, for example, a photocurable resin, preferably a transparent ultraviolet curable resin can be used.

Next, a method of manufacturing the disk-shaped information recording medium 10 shown in FIGS. 1 and 2 will be briefly described. The first substrate 12 is molded by using, for example, injection molding using a master, thereby forming information pits 22 on the inner surface side of the first substrate 12. The information pits 22 record information (contents) such as music information in advance. Then, at the information pits 22 of the first substrate 12 thus formed, a reflection film 24 is formed by, for example, sputtering or vapor deposition. On the other hand, the second substrate 14 is injection-molded using another master, whereby a recording groove 32 is formed on the inner surface side of the second substrate 14. The recording groove 32 has no information (content). Then, the recording groove 32
A recording film 34 is formed thereon by sputtering or vapor deposition. Next, the inner surface side of the first substrate 12 and the second substrate 1
The inner surface side of 4 is bonded with a light-transmitting adhesive 16. As an example, in a state where the first substrate 12 and the second substrate 14 are superimposed, while rotating in the R direction about the center hole 18, and from the inner peripheral side to the outer peripheral side of the disc-shaped information recording medium 10. The light-transmitting adhesive layer 16 is light-cured by sequentially irradiating ultraviolet rays in the T direction.

The substrate portion 20 of the first substrate 12 and the second substrate 1
When the substrate portion 30 of No. 4 is, for example, 0.60 mm, the entire thickness of the completed disk-shaped information recording medium 10 is, for example, about 1.20 mm. 2, the first substrate 12 has a ROM area (read only memory) 40, and the ROM area 40 is formed by the information pits 22 and the reflection film 24 as described above. On the other hand, the second substrate 14 has a RAM area (random access memory) 50,
Are formed by a recording groove 32 and a recording film 34. RAM
When reading information (contents) recorded in the area 40 in advance, the objective lens 6 of the optical pickup 60 is used.
The information pit 22 is irradiated with the read laser beam L through the second laser beam L. Thereby, the reflection film 24 of the information pit 22
By returning the return light of the laser beam L to the optical pickup 60 side, the optical pickup 60 can read out the information (content) of the information pit 22 as a signal by a predetermined processing means.

On the other hand, when information (contents) is recorded in the recording groove 32 by irradiating the RAM area 50 with the reading laser beam L via the objective lens 62 of the optical pickup 60, The information can be read using return light. When new information is recorded in the recording groove 32, new information can be recorded by irradiating the recording groove 32 with a recording laser beam from the optical pickup 60.

As described above, when producing the disc-shaped information recording medium 10 of the present invention, the RO of the first substrate 12
In order to manufacture the M area 40, a master for the ROM area is used. On the other hand, when the RAM area 50 of the second substrate 14 is to be manufactured, a separate master for the RAM area is required. That is, the first substrate 12 and the second substrate 14 of the disc-shaped information recording medium 10 shown in FIG. 2 are separately manufactured using two master disks. Thus, the necessary groove depth and groove width of the RAM area 40 and the information pit 22 and the required groove depth and groove width of the recording groove 32 of the RAM area 50 can be set separately. The hybrid-type disc-shaped information recording medium 10 can be easily manufactured.

Second substrate 14 having RAM area 50
Can be used up to its physical lifespan and need to be recreated by changes in information (content)
Only the first substrate 12 having the M area 40 is provided. Thus, the first substrate 12 may be re-created by changing the content, and the second substrate 14 may be formed as it is regardless of the change in the content. Because of this RA
The second substrate 14 having the M area 50 can be separately prepared and stored in large numbers. Then, the first substrate 12 according to the content is separately prepared, and the RA
By bonding the second substrate 14 for the M area and the first substrate 12 for the ROM area, a large number of hybrid-type disc-shaped information recording media 10 can be manufactured in a short time at low cost.

In the example of FIG. 2, even when information (contents) recorded in the ROM area 40 is read, information is recorded in the RAM area 50 of the second substrate 14 or information is read. Even so, the optical pickup 60 irradiates laser light for reading or laser light for recording through the substrate portion 30 of the second substrate 14. When reading information from the ROM area 40, the laser light passes through the substrate portion 30 and the light-transmitting adhesive layer 16. In such a configuration, the substrate portion 20 of the first substrate 12 does not necessarily need to use a light transmissive material, and may use a material that does not transmit light.

[0021]

As described above, according to the present invention,
An inexpensive information recording medium having a read-only memory and a random access memory can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a disc-shaped information recording medium of the present invention.

FIG. 2 is a view showing a cross-sectional structure of the disc-shaped information recording medium of FIG. 1;

FIG. 3 is a cross-sectional view showing the structure of a conventional hybrid-type disc-shaped information recording medium.

4 is a diagram showing one master for producing the conventional hybrid-type disc-shaped information recording medium of FIG. 3;

[Explanation of symbols]

10 ... Disc-shaped information recording medium, 12 ... First
Substrate, 14 ... second substrate, 16 ... adhesive layer, 22
..Information pits (irregular areas), 24... Reflective films, 32
... recording groove, 34 ... recording film, 40 ... ROM area, 50 ... RAM area.

Claims (3)

[Claims] 1. A first substrate of a read only memory in which a reflection film is formed in an uneven area in which information is recorded in advance, and a second substrate of a random access memory in which a recording film is formed in a region of a recording groove. Characterized by being bonded to each other with a light-transmitting adhesive. 2. The second substrate has a light-transmitting property, and irradiates light to the concave / convex area through the second substrate and an adhesive for reading information of the first substrate, and irradiates light through the second substrate. 2. The disk-shaped information recording medium according to claim 1, wherein the information is written on the second substrate or the information on the second substrate is read by doing. 3. The disc-shaped information recording medium according to claim 1, wherein the adhesive is a transparent ultraviolet curable resin.