JPH09265667A - Optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk capable of reproducing the same kind of information based on a common information source even by a disk player complied with an optical disk such as a conventional CD and recording the recording information of high commercial value as for the common information source together. SOLUTION: This optical disk comprises a first disk base 2 including a first disk substrate 3 and a first information signal layer 4 and a second disk base 7 including a second disk substrate 8 superposed on/fixed to the first disk base 2 and having a thickness thinner than that of the disk substrate of the first disk base 2 and a second information signal layer 9 and recording information based on the same information source is recorded with different recording densities on the first information signal layer 4 and the second information signal layer 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc having at least two types of information signal layers, and more particularly to an optical disc in which two types of information signal layers are separately recorded based on the same information source. Is.

[0002]

2. Description of the Related Art Conventionally, compact disks (hereinafter referred to as CDs)
The optical pickup device, for example, irradiates a signal recording surface of a rotationally driven optical disk with light such as laser light from an optical pickup. Then, the light receiving element of the optical pickup detects the return light from the signal recording surface of the optical disc and reads the signal recorded on the optical disc to generate a reproduction signal of the recorded information data. It has become.

An optical disc as such an information recording medium is formed on a disc substrate made of a transparent synthetic resin material such as polycarbonate (PC) or polymethylmethacrylate (PMMA), and on the main surface of the disc substrate. The information signal layer is provided with a protective layer for mechanically and chemically protecting the information signal layer. Such a conventional optical disc has a single-layer structure,
The transparent disk substrate usually has a thickness of 1.2 mm. The light from the light source passes through the transparent disk substrate having a thickness of 1.2 mm to irradiate the information signal layer. The information signal layer has information recorded thereon by predetermined information pits and the like. The light receiving element detects the phase change of the return light reflected by the information signal layer and the like, thereby reproducing the recorded information. Is being done.

[0004]

However, in recent years,
Optical discs are being used as a package medium for audio and image information in order to increase the recording density. For this reason, optical discs for increasing the track density of optical discs have been proposed. In such an optical disc, in the recording track of the information signal layer recorded at high density,
In order to appropriately irradiate the light from the light source through the objective lens, the disk substrate is set to 0.6 mm, which is half that of the conventional disk substrate, due to the lens aberration and the like.

Therefore, the thickness of the disk substrate is different between the conventional optical disk of the first type such as a CD and the new optical disk of the second type for high density recording. The numerical aperture (NA) etc. are also different. For this reason, the second type of optical disc compatible with high-density recording cannot be played back by a conventional disc player such as a CD, so software (music software, video / movie) based on a new information source (source) to be newly produced in the future. Software, etc.) has a problem that it cannot be reproduced by a conventional disc player because the format of the optical disc is different.

That is, with respect to new works (information sources) such as music and images, there is a possibility that the optical disc of the second kind is produced and sold because of the advantage of high density recording in order to increase the commercial value. Is high. Such an optical disc (second type of optical disc) has a drawback that it cannot be reproduced by a disc player corresponding to the first optical disc previously purchased by the user.

In view of the above points, in the present invention, the same kind of information based on a common information source can be reproduced by a disc player corresponding to an optical disc such as a conventional CD, and this common information source has a high commercial value. It is an object of the present invention to provide an optical disc capable of recording recorded information together.

[0008]

According to the present invention, the above object is to provide a first disc substrate including a first disc substrate and a first information signal layer, and to the first disc substrate. A second disc substrate, which is fixed in a superposed manner and has a substrate thickness smaller than that of the disc substrate of the first disc base;
And a second disc substrate including an information signal layer of, and the first information signal layer and the second information signal layer include:
This is achieved by an optical disc in which recorded information based on the same information source is recorded with different recording densities.

According to the above arrangement, this optical disk has at least a first information signal layer and a second information signal layer. Therefore, by recording the information in the first information signal layer in accordance with the format of the conventional optical disc, the information can be reproduced by the conventional disc player. Further, with respect to the same information source as the information source recorded in the first information signal layer, it is possible to record information having a higher commercial value in the second information recording layer by high density recording.

[0010]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are added. However, the scope of the present invention particularly limits the present invention in the following description. The embodiment is not limited to these embodiments unless otherwise stated.

FIG. 1 is a schematic sectional view showing a preferred embodiment of an optical disk according to the present invention. In the figure, an optical disc 1 comprises a first disc base 2 and a second disc base 7. That is, the first disk substrate 1
As shown in FIG. 2, a disk substrate (first disk) made of a transparent synthetic resin material such as polycarbonate (PC) or polymethylmethacrylate (PMMA) is formed.
Disc substrate 3) and an information signal layer (first information signal layer) 4 provided on the main surface of the disc substrate 3. In this case, the disk substrate 3 has a thickness of, for example, about 1.2 mm, like a conventional CD or the like.

On the other hand, as shown in FIG. 3, the second disk base 7 is a disk substrate (second disk) formed of a transparent synthetic resin material such as polycarbonate (PC) or polymethylmethacrylate (PMMA). Disc substrate 8) and an information signal layer (second information signal layer) 9 provided on the main surface of the disc substrate 3. in this case,
The disk substrate 8 of the second disk substrate 7 has a thickness of, for example, about 0.6 mm, which corresponds to high density recording.

The first disk base 2 and the second disk base 7 are stacked with the information signal layers 4 and 9 facing each other as shown in FIG. For example, they are fixed by being stuck together with an adhesive made of, for example, an ultraviolet curable resin or hot melt.

FIG. 4 is a cross-sectional view of an essential part showing the structure of such an optical disc 1 in more detail. In the figure, the first
The disc substrate 2 has a first disc substrate 3 and a first information signal layer 4. This first information signal layer 4 is
For example, similarly to the conventional information recording of a CD, there is a concavo-convex pattern formed corresponding to the recorded information, and the reflection film 4a is formed thereon by, for example, Al vapor deposition. A protective layer 4b for mechanically and chemically protecting the information signal layer 4 is provided on the opposite side (lower surface in the figure) of the reflective film 4a with the information signal layer 4 interposed therebetween.

On the other hand, in the second disk substrate 7,
A second information signal layer 9 is provided on the main surface of the second disk substrate 8. The second information signal layer 9 has a concavo-convex pattern formed corresponding to recording information on the lower surface of the second disk substrate 8 in the drawing, and a semi-transmissive reflective film 9a on the lower surface in the drawing, In order to protect the information signal layer 9 mechanically and chemically, it is provided with a transparent protective layer 9b which is covered.

In the present embodiment, information based on the same information source as the information recorded in the first information signal layer 4 is recorded in the second information signal layer 9 in this embodiment. Specifically, for example, when the information source (source) is music information, for example, information about the same song by the same artist is stored in the second information signal layer 9 as the first information signal layer 4 Are recorded by different high density recording. That is, in the second information signal layer 9, information regarding the same song by the same artist is recorded as higher quality audio information. Alternatively, in the second information signal layer 9, not only audio information but also, for example, promotion of the same song, which is the same information source as the information recorded in the first information signal layer 4, for example, the same song. Video information such as video is recorded. Thus, although the recorded information of the second information signal layer 9 is based on the same information source as the recorded information recorded in the first information signal layer 4,
Compared with the recorded information of the first information signal layer 4, the information amount is increased and the added value or the commercial value is increased.

The information signal layers 4 and 9 formed on the optical disc 1 are not limited to the two layers shown in FIG. 4, and more information signal layers may be provided by stacking more disc substrates. Good.

Further, the semi-transparent film 9a is formed of, for example, a Si-based dielectric film or a metal film such as Au so that the light reflectance is about 30%. Corresponding to this, the printing layer 5 is provided between the second disk substrate 7 and the adhesive layer 6. The print layer 5 is formed over substantially the entire surface of the optical disc 1, and the contents of the information recorded in the information signal layer 9, patterns, etc. are printed with ink or the like. The print layer 5 is not limited to a single layer, and a plurality of layers may be stacked. Further, a printing layer may be provided on the side opposite to the printing layer 5 with the adhesive layer 6 interposed therebetween. In this case, the reflective film 4a is also a semi-transmissive reflective film. The print layer 5 may be omitted when the optical disc 1 is simply configured. In that case, the semitransparent film 9a may be a total reflection film.

In the optical disc 1 configured as described above, the record information of the information signal layer 9 is read out by using a disc player corresponding to the optical disc compatible with high density recording, for example. That is, the irradiated light beam is converged on the information signal layer 9 by passing through the second disk substrate 8 along the direction of arrow A in FIG. Here, the reflection component of the light beam reflected by the semi-transmissive reflection film 9a becomes return light, which is detected by a predetermined light detection unit of the light receiving unit, and a reproduction signal is obtained. in this case,
In the information signal layer 9, high-value-added information that has been recorded at high density as described above is recorded. For this reason, the disc player also requires a new type of disc player having an optical system or the like corresponding to the second type of high-density recording type optical disc.

On the other hand, in the conventional disc player corresponding to the first type of optical disc, for example, a CD, the optical disc is set so that the light beam is emitted from the arrow B side in FIG. The information recorded in one information signal layer 4 can be reproduced. That is, some users may not have a new type of disc player compatible with the second type of optical disc,
Alternatively, for example, even if a player has a new type of disc player, he or she only has one to be used at home, and the in-vehicle disc player is compatible with only the first type of optical disc. In such a case, the information recorded on the second information signal layer 9 side cannot be reproduced at all, or even if it can be reproduced at home, it cannot be reproduced when it is brought into the vehicle. However, in the optical disc of the present embodiment, the information based on the same information source as the information recorded in the second information signal layer 9 is recorded in the first information signal layer 4 as well. By using a type of disc player, for example, the same tune recorded on the second information signal layer 9 can be enjoyed.

Also, in the case of manufacturing or selling such an optical disc 1, it is necessary to separately manufacture or sell different types of optical discs according to the type of the disc player owned by the user. There is no. In particular, when selling an optical disc, it is not necessary to separately provide a sales space depending on the type of the optical disc. Therefore, the same optical disk can be sold to the users who have the disk players corresponding to the first type optical disk and the second type optical disk, respectively, which is advantageous in manufacturing or sales management.

Further, in the optical disc 1, the printed contents of the printing layer 5 provided over substantially the entire surface of the optical disc 1 are visually recognized from the direction of arrow A in FIG. 4 through the semi-transmissive reflective film 9a. Therefore, the area of the printing surface is remarkably large as compared with the conventional case where the necessary printing is performed by avoiding the area where the total reflection film as the information signal layer is provided. As a result, the degree of freedom in the content and format displayed by printing is greatly improved.

FIG. 5 shows a second embodiment of the optical disk of the present invention, and since the configuration of the portions denoted by the same reference numerals as those of the embodiments of FIGS. 1 to 4 is common, the differences are mainly described. Explained. In the optical disc 10, the second disc substrate 8 is removed in the vicinity of the center of the disc, which is the portion clamped by the chucking means, to form the concave portion 11. In the disc player (not shown), the inner circumference of the recessed portion 11 coincides with the outer circumference when a chapter cylinder for holding the optical disc 10 to rotate it is fitted from above in FIG.

Therefore, in this case, in the optical disk 10, since the second disk substrate 8 having a thickness of about 0.6 mm is removed from the area clamped by the chucking means, the clamping is performed. The thickness of the portion (the central portion of the optical disk 10) is about 1.2 mm.
(See FIG. 5). As a result, the clamped portion has the same thickness as that of the conventional CD, so that even when the thickness of the clamped portion of the conventional disc player is restricted, reproduction can be performed without any problem. Therefore, the information signal layer 8 can be reproduced by irradiating the information signal layer 8 from above in FIG. 5 and the information signal layer 4 from below in FIG. 5, respectively, and in this case, the area where the optical disc 10 is clamped. Has a thickness of 1.2 mm, which is the same as the conventional one. It goes without saying that the optical disc 10 of the present embodiment can also exhibit all the same effects as those of the first embodiment described above.

FIG. 6 shows an optical disk according to a third embodiment of the present invention, and since the parts designated by the same reference numerals as those in the embodiments of FIGS. Explained. In the optical disk 20, half of the thickness of the first disk substrate 3 is removed from the outside in the vicinity of the center of the disk, which is the portion to be clamped, to form a recess 21. In the disc player (not shown), the inner circumference of the recessed portion 21 coincides with the outer circumference when a chapter cylinder for holding the optical disk 10 to rotate it is fitted from below in FIG.

Therefore, in this case, in the optical disc 20, half the thickness of the first disc substrate 3 having a thickness of about 1.2 mm is removed from the region clamped by the chucking means. Therefore, the thickness of this clamped portion (the central portion of the optical disc 20) is approximately 1.2 mm (see FIG. 6). As a result, the clamped portion has the same thickness as the conventional CD, which is suitable when there is a limit to the thickness of the clamped portion in the conventional disc player. Therefore,
The information signal layer 8 is shown from above in FIG. 6, and the information signal layer 4 is shown in FIG.
Each can be reproduced by irradiating a light beam from below the optical disc. In this case, the optical disc 20
The thickness of the area where is clamped is 1.2 mm, which is the same as before.
Becomes It goes without saying that the optical disc 20 of this embodiment can also exhibit all the same effects as those of the first embodiment described above.

By the way, in the optical disc 10 of FIG. 5, each of the information signal layers of the optical disc 10 has a first layer.
A conventional CD player compatible with optical discs of
When reading with a new disc player compatible with the second type of optical disc, there are the following problems. When the optical disc 10 is set in a new type disc player and clamped from the top of the figure (actually, the optical disc 10 is turned over and set in the disc player), the surface L1 supported by the chucking means is set. As a reference, the horizontal distance from the reference plane L1 to the information signal layer 9 is substantially 0, and the distance to the objective lens of the optical pickup (not shown) is too close. For this reason,
Depending on the specifications of the disc player, a problem may occur in the stroke of focus movement of the objective lens.

In the case of the optical disc 20 shown in FIG.
When the optical disc 20 is set in a new type disc player corresponding to the second type of optical disc, the optical disc 20 is turned over and the surface supported by the chucking means becomes L3. Therefore, there is no problem that the distance from L3 to the information signal layer 9 is about 0.6 mm, but when the optical disk 20 is turned over again and set in the conventional CD player, the position of L4 is supported by the chucking means. It becomes a reference plane. This reference plane L4
The distance from the information signal layer 4 to the information signal layer 4 is 0.6 mm, but since the distance is set to 1.2 mm in a normal CD player, the movement stroke of the objective lens of the optical pickup may be insufficient. is there.

Therefore, the optical disc 30 according to the fourth embodiment shown in FIG. 7 has the following structure. This optical disk 30 also has a structure in which the first disk base 2 and the second disk base 7 are stacked and fixed, and since the layer structure thereof is the same as that of FIG. 4, duplicate description will be omitted.

In the figure, when the optical disk 30 is reproduced on the side of the disk substrate 2 corresponding to the optical disk of the first type (the thickness of the disk substrate 3 is, for example, about 1.2 mm), chucking means is applied from above in the figure. It is clamped by 36. Further, in the case of reproducing the optical disk 30 on the side of the disk base 7 corresponding to the optical disk of the second type (the thickness of the disk substrate 8 is about 0.6 mm, for example),
In the figure, it is clamped by chucking means 37 from below.

The chucking means 36 and 37 are the same and are actually provided as one chucking means for one disc player. In FIG. 7, since the relative relationship between the optical disk 30 and the chucking means when the optical disk 30 is turned upside down and set in the disk player is shown in one drawing, two chucking means are shown for convenience of explanation.

The chucking means 36 is provided with a chapter cylinder 32 which advances and retracts in the axial direction (up and down direction in the drawing). The outer circumference of the chapter cylinder 32 is tapered so that the tip side becomes narrower along the axial direction. The chapter cylinder 32 has a center hole 4 formed at the center of the clamped portion of the optical disc 30.
It is inserted into 1. At this time, the chapter cylinder 32
Moves back and forth in the axial direction to center the optical disk 30 by utilizing the inclined surface on the outer periphery thereof.

The chucking means 36 is provided with a turntable 33 which is located around the chapter cylinder 32 and rotates in accordance with the rotation of the spindle motor. Therefore, the optical disk 30 is rotatably driven by the turntable 33 in a clamped state by the chapter cylinder 32, the turntable 33, and a mating member (not shown). The end surface 33a of the turntable 33 has a position where the outer circumference of the chapter cylinder 32 comes into contact with the optical disc 30 and T in the horizontal direction.
It is configured to be offset by one.

The optical disc 30 is provided with a ring-shaped first concave portion 42 at a position facing the end surface 33a of the turntable 33 around the center hole 41 penetrating the front and back surfaces. The depth of the first recess 42 is about half the thickness of the first disk substrate 3.

Further, the lower surface side of the optical disk 30 in FIG. 7 is inside the inner peripheral position of the first concave portion 42,
The second recess 43 communicates with the center hole 41. The second recess 43 has a depth obtained by removing the second disk substrate 8 in the region of the recess 43.

Therefore, in the optical disk 30,
When clamped by the chucking means 36,
The turntable 33 of the chucking means 36 enters the first recess 42 and clamps the optical disk 30. In this case, the end surface 33a of the turntable 33 is L
Since the optical disc 30 is brought into contact with and supported by the optical disc 30 at position 6, the horizontal distance between the reference plane L6 and the information signal layer of the disc substrate 3 is about 0.6 mm.

When the optical disk 30 is clamped from below by the chucking means 37 (actually,
The optical disk 30 is turned over, and the above-mentioned chucking means 3
(When clamping with the same chucking means as 6),
The turntable 35 of the chucking means 37 enters the second recess 43 and clamps the optical disk 30. In this case, the outer peripheral surface of the chapter cylinder 34, the contact position of the center hole 41 of the optical disk 30, and the end surface 35a of the turntable 35 are displaced by T2, which is about 0.6 mm. The end surface 35a of the turntable 35 abuts and supports the optical disk 30 at the position of L8 (the back surface of the optical disk 30), so that the horizontal distance between the reference surface L8 and the information signal layer of the disk substrate 8 is about. It becomes 0.6 mm.

Therefore, even when the first disc substrate 3 side of the optical disc 30 is reproduced by a new disc player compatible with the second type optical disc, the optical disc 30 is back-supported and the second disc substrate 8 side is provided. Also in the case of reproducing, the distances from the chucking reference planes L6 and L8 to the respective information signal layers are 0.6 mm, respectively, and it is possible to accurately reproduce with the same optical system.

Further, when reproducing with a conventional CD player, the disk substrate 3 side is reproduced. In this case, the turntable 38 of the conventional CD player has the turntable 3 of the chucking means 36 as shown in the figure.
Since it is located on the inner circumference side of 3, the turntable 38
The end surface 38a of the disk comes into contact with the position L5 on the surface of the optical disk 30. And the thickness of the disk substrate 3 is
Since it is about 1.2 mm, the distance from the reference plane L5 to the information signal layer is about 1.2 mm. Since this distance is the same as the setting of the distance between the optical system of the conventional CD player and the information signal layer of the compact disc, the optical disc 30 reproduces the recorded information without any trouble even in the conventional CD player. be able to. The optical disc 30 of this embodiment is also the optical disc 1 of the first embodiment.
It can exert the same effect as.

[0040]

As described above, according to the present invention, the same type of information based on a common information source can be reproduced by a disc player compatible with conventional optical discs such as CDs. It is possible to provide an optical disc that can also record recorded information having high commercial value.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the configuration of a first embodiment of an optical disk according to the present invention.

2 is a schematic cross-sectional view showing a configuration of a first disc substrate of the optical disc of FIG.

3 is a schematic cross-sectional view showing a configuration of a second disc substrate of the optical disc of FIG.

FIG. 4 is a cross-sectional view of main parts showing a detailed structure of the optical disc of FIG.

FIG. 5 is a schematic cross-sectional view showing a second embodiment of the optical disc of the present invention.

FIG. 6 is a schematic cross-sectional view showing a third embodiment of the optical disc of the present invention.

FIG. 7 is a schematic cross-sectional view showing a fourth embodiment of the optical disc of the present invention.

[Explanation of symbols]

1 ... Optical disc, 2 ... First disc substrate, 3
... first disk substrate, 4 ... first information signal layer, 6 ... adhesive layer, 7 ... second disk substrate, 8
... second disk substrate, 9 ... second information signal layer, 4a ... semi-transmissive reflective film, 9a ... reflective film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Watanabe 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (5)

[Claims] 1. A first disc substrate including a first disc substrate and a first information signal layer, and a disc substrate of the first disc substrate, which is fixed by being superposed on the first disc substrate. It has a second disc substrate having a thinner substrate and a second disc substrate including a second information signal layer, and the first information signal layer and the second information signal layer are An optical disc in which recorded information based on the same information source is recorded at different recording densities. 2. The second information signal layer has different audio information and / or image information recorded based on the same information source as the recording information of the first information signal layer. The optical disc according to claim 1. 3. A printing layer is provided between the first disk base and the second disk base, and at least one of the first and second information signal layers has a predetermined transparency. The optical disc according to claim 1, wherein the printed layer is visible through the information signal layer having the transparency. 4. The thickness of the first disk substrate is approximately 1.
2 mm, and the thickness of the second disk substrate is about 0.
The optical disc according to claim 1, wherein the optical disc has a length of 6 mm. 5. The first disk substrate and / or the second disk substrate
2. The thickness of the portion to be clamped is configured to be substantially the same as that of the first disk substrate by forming the disk substrate near the center thereof to be thin.
An optical disk according to claim 1.