JP2522033B2 - Recordable and reproducible optical disc - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recordable / reproducible optical disc, and more particularly, a commercially available read-only optical disc device, for example, a three-beam method for a CD (compact disc) player or the like. The present invention relates to a recordable and reproducible optical disc that can be reproduced by an optical head.

[Conventional example] Recently, optical discs have remarkably developed from a read-only type and a write-once type to a rewritable type.

For example, as shown in FIG. 10 and FIG. 11, the recordable and reproducible optical disc (write-once type, rewritable type optical disc) has an uneven laser beam guide track (groove 1a, land 1b) on the substrate 1. The recording film (reflection film) 2 is provided. The width G _W (L _W ) of the groove 1a (or land 1b) of the laser light guide track is about 0.8 μm (beam diameter of laser light), and the depth G _D is about 0.07 μm. Tracking control is performed by this laser light guide track, and additional writing and rewriting of information and the like are performed.

[Problems to be Solved by the Invention] By the way, the above-mentioned recordable / reproducible optical disk has a drawback that it cannot be reproduced by a commercially available reproduction-only optical disk device, for example, a CD player. That is, since the read-only optical disc is standardized so that the reflected light amount I _O from the mirror part (corresponding to approximately the incident laser light amount) is 70% or more, the CD player, etc. reproduces according to the standard. It has a possible circuit configuration. On the other hand, in a recordable / reproducible optical disc, the recording film (reflection film) 2 has a high absorptivity so that information or the like can be recorded with a low-power laser beam. The amount of light reflected from the (reflection film) 2 is, for example, 50%, which is smaller than that of the read-only optical disc. Therefore, a commercially available CD
A player or the like cannot perform accurate tracking control, and information or the like cannot be reproduced accurately.

The present invention has been made in view of the above problems, and an object thereof is to increase the amount of light reflected from a recording film (reflection film) and to control tracking with a beam method optical head of a commercially available CD player or the like 3. Another object of the present invention is to provide a recordable / reproducible optical disk which can be controlled and whose linear velocity can be controlled when reading information and the like.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a substrate including grooves and lands, and a track pitch of which is 1.6 μm.
In a recordable and reproducible optical disc in which a laser light guide track is provided and a recording film is formed in the groove and the land, the information is recorded when the information is recorded in either the groove or the land. The width of the groove (or land) on the recording side is 1.1 to 1.2 μm, the width of the other land (or groove) is 0.5 to 0.4 μm, and the depth is λ / 8n to λ / 10n. (Λ: wavelength of laser light, n is the refractive index of the substrate) to increase the amount of light reflected from the recording film on which information is recorded and to keep the linear velocity of the other land (or groove) constant. It is characterized in that it is a pit train for obtaining the linear velocity control signal.

[Operation] With the above structure, the amount of light reflected from the recording film of the grooves and lands forming the laser light guide track is determined by the commercially available CD.
Is increased to a value close to. Therefore, when recording information or the like on a wide groove or land, the amount of reflected light from the recording pit portion is made smaller than the amount of reflected light from the narrower land or groove, so that a commercially available read-only optical disk device ( For example, tracking control by the three-beam method used in a CD player or the like is possible.
Further, the land or groove having the smaller width is used as a pit row, and the pit row is formed with an interval such that the frequency of the reproduction signal is, for example, about 50 kHz when the optical disc is rotated at a predetermined linear velocity. A linear velocity control signal for keeping the linear velocity constant is obtained from this pit train.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 and 2, a substrate 10 of a recordable / reproducible optical disk is provided with a groove 10a for forming a laser light guide track and a land 10b of a pit row, and a recording film (reflection film) 11 is formed. To be done. That groove 10
The width G _{w of a} is 1.1 to 1.2 μm, the width L _W of the land 10b of the pit row is 0.4 to 0.5 μm, and the depth G _D thereof is λ / 8n to λ / 10.
n, and the track pitch is an ordinary optical disc (for example, C
It is approximately 1.6 μm according to the standard of D). In this case, λ is the wavelength of the laser light and n is the refractive index of the substrate 10. In this case, the groove (or land) depth G _D is λ / 8n to λ / 10.
The reason for setting n is that the standard condition is the same as that of the existing read-only optical disc (CD), as with the track pitch.

Further, as shown in FIG. 3, the groove 10a is adapted to record information, and the pit length of the pit row structure of the land 10b is, for example, a predetermined linear velocity of 1.2 m / s to 1.4 m.
When reproducing at / s, the reproduced signal changes continuously or stepwise so that the reproduced signal is around 50 kHz, for example. The frequency of the reproduction signal due to the pit train is located between the servo band frequency and the frequency of the reproduction signal such as information when the optical disc is rotated a predetermined time.

Here, the amount of light reflected by the structure of the groove 10a and the land 10b forming the laser guide track will be described with reference to FIG. The amount of reflected light from the surface mirror portion of the substrate 10 is I _O , the amount of reflected light from the groove 10a is I _G, and the amount of reflected light from the land 10b is I _L.

First, when an optical disc before information is recorded is reproduced by a player dedicated to recording and reproduction, the modulation signal from the groove is output as the sum signal (RF signal) of the four-division detector, which is shown in FIG. Such reflected light amount characteristics can be obtained. According to this, in this example, the information recording part is grooved.
Since it is set to 10a, the reflected light level of the groove can be set to almost 100% of the reflected light amount I _O from the surface mirror portion. Also, when tracking is OFF (focus ON
Modulation degree ((I _G −
It is also possible to clearly distinguish between the groove and the land by setting I _L ) / I _O ) in the range of 10% to 30%. That is, according to the present invention, as described above, the width of the groove 10a is made wider than that of the recording portion of the conventional write-once and rewritable optical discs, so that the loss of the reflected light amount is sufficiently suppressed and the reflection thereof is reduced. This is because the amount of light can be increased more than before (see the solid line in FIG. 4).

A case where information is recorded in the groove 10a of this optical disc by recording pits (holes) will be described. As shown in FIG.
The average reflected light amount I _GH from the land 10b is made smaller than the reflected light amount I _L from the land 10b. As a result, the information signal from the groove 10a and the linear velocity control signal from the land 10b are easily separated, and tracking is performed by the three-beam method optical head used in a commercially available read-only optical disc device (for example, a CD player). The control becomes possible, and the information by the recording pit can be reproduced. Further, at the time of recording and reproducing information, a signal for controlling the linear velocity of the optical disc can be easily obtained by the pit train of the land 10b.

The recordable / reproducible optical disc may be of any type other than the perforated type as long as the reflectance from the recording portion decreases when recording information or the like.

FIG. 6 and FIG. 7 are modifications of the above-mentioned embodiment, and in this embodiment, an optical disk capable of recording and reproducing when information and the like are recorded on the land 10b is shown.

In these figures, the width L _W of the land 10b constituting the laser light guide track is 1.1 to 1.2 μm, the width G _{W of the} groove 10a is 0.4 to 0.5 μm, and the depth G _D thereof is λ / 8n to λ. /Ten
n, and the track pitch is about 1.6 μm. That is, the width L _{W of the} land 10b is wider than the width G _{W of the} groove 10a. It should be noted that λ is the wavelength of the laser light and n is the refractive index of the substrate 10.

Further, as shown in FIG. 8, the groove 10a has a pit row structure, and the pit length of the pit row is, for example, a reproduction signal at the time of reproduction at a predetermined linear velocity of 1.2 m / s to 1.4 m / s. For example, it changes continuously or stepwise so that it becomes around 50 kHz. Note that the frequency of the reproduction signal by the pit train is
It is located between the servo band frequency and the frequency of the reproduction signal such as information.

In this way, this embodiment is the reverse of the previous embodiment.
Since 10a has the same pit row structure, it has the same function, and thus the reflected light amount can be obtained with I _G and I _L reversed in FIGS. 4 and 5. Therefore, the land level can be set to about 100% of the reflected light amount I _{O, and} the modulation degree ((I _L −I _G ) / I _O ) of the land to the groove when tracking is OFF (focus ON) is from 10%. 30%
Can be

Further, as shown in FIG. 9, the shape of the laser light guide track of the recordable / reproducible optical disk may be a V-groove shape. When information is stored in the land 10b forming this laser light guide track, the land 10b
The width L _W of the groove 10a is made wider than the width G _{W of the} groove 10a so that the groove 10a becomes a pit row. Since the other points are the same as those in the previous embodiment, description thereof will be omitted.

As described above, the shape of the groove 10a and the land 10b forming the laser light guide track of the recordable / reproducible optical disk has the width of the groove 10a or the land 10b changed, and the groove 10a or the land 10b having a narrow width has a pit row structure. , And the depth of the groove 10a is λ / 8n
.About..lamda. / 10n (.lamda .: wavelength of laser light, n: refractive index of substrate 10), and recording is performed to the extent that tracking control and reproduction control are possible by a three-beam method optical head used in a commercially available CD player or the like. The amount of light reflected from the film 11 is increased.

As described above, according to the recordable and reproducible optical disk of the present invention, when information is recorded in the groove of the laser light guide track, the width of the groove is 1.1 to 1.2 μm.
m, on the other hand, the width of the land is 0.5 to 0.4 μm. Conversely, when recording information on the land, the width of the land is
1.1 ~ 1.2μm, the groove width is 0.5 ~ 0.4μ
m and the depth is set between λ / 8n and λ / 10n (λ: wavelength of laser light, n is the refractive index of the substrate), and the track pitch of the laser light guide track is set to a normal value, for example, for reproduction. By making the track pitch of the dedicated optical disk the same as 1.6 μm, it is possible to increase the amount of light reflected from the recording film of the grooves and lands that form the laser light guide track, and make it possible for a read-only optical disk device (such as a CD player). With the three-beam method optical head used, tracking control and information reading can be performed accurately. Further, according to the present invention, since the groove or land on the side where information is not recorded is a pit row, it is possible to easily obtain a signal for controlling the linear velocity of the optical disc at the time of recording and reproducing information and the like. The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a schematic partial perspective view of a recordable / reproducible optical disk showing an embodiment of the present invention, FIG. 2 is a schematic partial side sectional view of the recordable / reproducible optical disk, and FIG. 4 and 5 are graphs showing the amount of reflected light for explaining the operation of the recordable / reproducible optical disc, and FIG. 6 is a recordable / reproducible embodiment of the present invention. FIG. 7 is a schematic partial side sectional view of the recordable / reproducible optical disc shown in FIG. 6, and FIG. 8 is a schematic front view of the recordable / reproducible optical disc shown in FIG. FIG. 9 is a schematic partial side sectional view of a recordable / reproducible optical disk showing another modified embodiment of the present invention, and FIG. 10 is a schematic partial side sectional view of a conventional recordable / reproducible optical disk. Is a schematic partial oblique view of the optical disc shown in FIG. It is a diagram. In the figure, 10 is a substrate (recordable / reproducible optical disk), 10a
Is a groove, 10b is a land, and 11 is a recording film (reflection film).

Claims (1)

(57) [Claims] 1. A recordable and reproducible optical disc, wherein a substrate is provided with a laser light guide track including a groove and a land and a track pitch of which is 1.6 μm, and a recording film is formed on the group and the land. When recording information on either the groove or land, the width of the groove (or land) on the side where the information is recorded is set to 1.1 to 1.2 μm, and the width of the other land (or groove) is set. 0.5 to 0.4
.mu.m and the depth is between .lambda. / 8n and .lambda. / 10n (.lambda .: wavelength of laser light, n is the refractive index of the substrate) to increase the amount of light reflected from the recording film on which information is recorded, Further, a recordable and reproducible optical disk characterized in that the other land (or groove) is a pit train for obtaining a linear velocity control signal because the linear velocity is kept constant.