JP2835074B2 - Multi-layer optical disk device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a multilayer optical disc device.

(Prior Art) In recent years, practical use of an optical disk device has been advanced, and a write-once type including a read-only type has been widely used as a memory of a document file or a memory of a computer.

This optical disk device can record a large amount of information as compared with a magnetic disk device, for example, a hard disk or a floppy disk, but it is desired to further increase the capacity.

Therefore, conventionally, in order to increase the recording density of the optical disc,
The wavelength of the laser has been shortened and the numerical aperture of the objective lens has been increased.However, not only must the development of element parts be waited for, but also the depth of focus becomes smaller and more precise servo characteristics are required. There is a problem that it is technically difficult and costly.

On the other hand, in order to increase the capacity, there has been proposed a multilayer optical disc apparatus that performs tracking and data recording / reproducing on an optical recording medium having a structure in which recording surfaces of optical discs are overlapped with each other using a plurality of light beams.

(Problems to be Solved by the Invention) However, in a conventionally proposed multilayer optical disc device, tracking information is provided as fixed information on each recording surface, and the recording surface on which the tracking information is written is provided. Because it was a method of recording and reproducing data,
There is a problem that it is necessary to provide tracking information on each recording surface, which places a heavy load on the manufacturing process of the optical recording medium.

Therefore, an object of the present invention is to provide a multi-layer optical disc device capable of reducing the load on the manufacturing process.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, according to the present invention, a multi-layer optical recording medium for recording and reproducing data on an optical recording medium having a structure in which at least three recording surfaces are superposed. In the optical disc device, tracking was performed based on tracking fixed information provided on at least one of the recording surfaces, and data was recorded and reproduced on a recording surface different from the recording surface provided with the fixed information. Thereafter, an optical pickup capable of performing tracking using the data as tracking information and performing recording and reproduction of data on a recording surface different from each of the above-described recording surfaces is provided.

(Operation) In the multilayer optical disc device of the present invention, fixed tracking information is provided on at least one of a plurality of recording surfaces formed by overlapping.

In particular, in the present invention, a recording surface provided with fixed information for tracking is used for recording and reproducing data, and data is recorded and reproduced on other recording surfaces. A reproducible surface can be secured.

At this time, fixed tracking information only needs to be provided for one recording surface, high-precision positioning is not required for superposition of the recording surfaces, and the load on the manufacturing process is light.

Further, the tracking information can be automatically generated on another recording surface one after another as data newly recorded with respect to the fixedly provided tracking information, so that there is no problem with the tracking operation. Furthermore, if the intervals between the recording surfaces are made equal, at least 2
When performing tracking and data recording / reproduction with two light beams,
Adjustment becomes easy.

Further, if the light beams are condensed on different recording surfaces coaxially, all the light beams can be condensed only by providing a single objective lens. And simplification can be achieved.

(Example) Hereinafter, an example of the present invention will be described.

FIG. 1 is an explanatory diagram showing a disk configuration of a multilayer optical disk device according to one embodiment of the present invention.

As shown, the optical recording medium (optical disk) D of this example is
Comprises a recording layer (first layer) D1 on which a groove 1 as tracking information is formed, and a layer (second layer) D2 which is superimposed on this layer D1 and on both sides of which a data 2 can be recorded and reproduced. . Like the second layer D2, data 2 can be recorded and reproduced on the surface of the first layer D1. Although the thicknesses of the layers D1 and D2 are set to be the same here, it is important that the error of each thickness is within the depth of focus.

On the other hand, the light beam of the optical pickup is, for example, two beams LB1 and LB2 focused on the groove 1 of the first layer D1 and the boundary surface between the first layer D1 and the second layer D2 on the same optical axis. Tracking and data 2 by capturing the reflected light
Playback. These two beams LB
The relationship between the relative light condensing positions of 1, LB2 can be set arbitrarily.

With the above configuration, according to the optical recording medium D of this example, 2
With the light beams LB1 and LB2, data 2 can be recorded / reproduced on / from the boundary surface of the second layer while tracking is performed using the groove 1 of the first layer D1.

As shown in FIG. 2, data 2, 4 and the like recorded on one surface of the second layer D2 by tracking of the groove 1 are used as tracking information, and data 3, 5 and the like are recorded and reproduced on the other surface. For example, the recorded data can be successively replaced with tracking information, and the data can be recorded and reproduced over the entire surface of the disk.

In the optical recording medium D configured as described above, since fixed tracking information only needs to be provided in the first layer D1, there is no need to consider positional deviation in relation to the second layer D2. Its manufacture is easy. Also, since the data 2, 3, 4, 5,... Can be successively recorded on the surface of the recording medium, the recording capacity is large.

 FIG. 3 shows a configuration example of the optical pickup.

As shown, the optical pickup of this example has two light sources.
6,7 and the laser beams LB1, output from these light sources 6,7
Polarizing plates 9 and 10 for polarizing LB2 and inputting the same to prism 18 and lens 11 for condensing a beam projected on the same optical axis by prism 18 onto medium D are provided. First
Beam LB1 is a tracking beam. The second beam LB2 is a beam for recording and reproducing data. Lens 11 is focusing circuit 12 and tracking control circuit
Connected to 13.

On the other hand, the laser beams LB1, LB2 reflected from the medium D
Is reflected by a prism 14 to a polarizing prism 15, and is decomposed into first and second beams LB1 and LB2 by the polarizing prism 15, and tracking information and data are detected by optical sensors 16 and 17. It is supposed to be. The sensor 17 is connected to a data processing circuit 19. The tracking control circuit 13 and the light source 6 are connected to a recording circuit 20.

With the pickup having the above-described configuration, the focal points on the medium D are always at a predetermined pitch P, and both focal points can be shifted up and down in the figure by the control of the focusing circuit 12.

By operating the recording circuit 20 under the control of the tracking control circuit 13, predetermined data can be recorded and reproduced at a predetermined position on the medium D.

Further, upon detection of the first laser beam LB1, tracking processing is performed by the tracking control circuit, and when the tracking surface is changed, the focusing position can be appropriately changed by the focusing circuit.

In this example, since focusing and tracking are performed by the same objective lens 11, the apparatus configuration is simple and control is easy.

In the example of FIG. 3, the two beams LB1 and LB2 are converged on the same optical axis, but it is also possible to control the two beams LB1 and LB2. Further, as shown in FIG. 4, it is possible to control the light source position of the beam input to the objective lens 11 to adjust the focusing position.

5 to 7 are explanatory diagrams showing other examples of the configuration of the optical recording medium.

The optical recording medium DA shown in FIG. 5 has first to fourth layers DA1 and DA1.
Four layers of media consisting of 2, DA3 and DA4 are superimposed and the first layer DA1
This is an example in which a groove 1 as tracking information is formed on the front surface side of FIG.

In this example, by tracking the groove 1, data can be recorded / reproduced with respect to the next layer DA2, and the recorded data can be recorded / reproduced one after another as tracking data. In the figure, LB indicates the above-mentioned first or second laser beam LB1 or LB2.

The optical recording medium DB shown in FIG. 6 is an example in which convex tracking information 1A is formed on the lowermost medium DB4.

In this example, data can be recorded and reproduced on the upper layer side with respect to the tracking information on the lower layer side.

The optical recording medium DC shown in FIG. 7 is an example in which a tracking groove 1 is provided in an intermediate layer medium DC3.

In this example, data can be recorded / reproduced on the upper and lower layers based on the tracking information of the intermediate layer DC3, and data on the upper or lower layer can be recorded as new tracking information on the upper or lower layer. Recording and reproduction can be performed.

FIG. 8 shows the optical recording medium DA shown in FIG. 5, in which the pitch of the focal points of the tracking laser beam LB1 and the data recording / reproducing laser beam LB2 is doubled, and the recording / reproducing of data is performed every other layer. This is an example in which is performed.

In this example, since the pitch of both beams LB1 and LB2 can be arbitrarily changed, data access can be performed quickly.

In the above embodiment, the number of laser beams is two. However, the number of data recording / reproducing beams may be increased, for example, data may be reproduced simultaneously in adjacent layers.

Further, the beam pitch can be arbitrarily set in consideration of thermal characteristics and the like.

The present invention is not limited to these examples,
It can be implemented in an appropriate mode by making appropriate design changes.

[Effects of the Invention] As described above, the present invention is a multilayer optical disk device as described in the appended claims, so that it is easy to manufacture an optical disk. Further, data recorded based on fixed tracking information provided only on one recording surface can be used as new tracking information, so that the recording capacity can be significantly increased and its control is easy.
Further, since the light beam for tracking and data recording / reproducing can be arbitrarily designed, the data recording / reproducing method can be arbitrarily designed, and the application range can be expanded such as high-speed access.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is an explanatory view showing a configuration example of a multilayer optical disc, FIG. 2 is an explanatory view showing its operation, and FIG. 3 is an explanatory view showing a configuration example of an optical pickup. FIG. 4 is an explanatory view showing another example of the configuration of the optical pickup, FIGS. 5 to 7 are explanatory views each showing another example of the configuration of the optical disk, and FIG. 8 is a focus position of two laser beams. FIG. 4 is an explanatory diagram in the case where the pitch is doubled. 1 tracking groove 2-5 recording data 12 focusing circuit 13 tracking control circuit D, DA, DB, DC optical recording medium LB1 tracking laser beam LB2 data recording Laser beam for reproduction

Claims (4)

(57) [Claims] 1. A multi-layer optical disc device for recording and reproducing data on and from an optical recording medium having a structure in which at least three recording surfaces are superimposed, wherein a tracking fixed surface provided on at least one of the recording surfaces is provided. Tracking is performed based on the information, and after performing recording / reproduction of data on a recording surface different from the recording surface provided with the fixed information, tracking is performed using the data as tracking information. A multilayer optical disc device comprising an optical pickup capable of recording and reproducing data on different recording surfaces. 2. The multi-layer optical disk device according to claim 1, wherein said optical pickup focuses a plurality of light beams on different recording surfaces. 3. The multi-layer optical disk device according to claim 2, wherein said plurality of light beams are condensed on different recording surfaces coaxially. 4. The apparatus according to claim 2, wherein the relationship between the relative focusing positions of the plurality of light beams can be set arbitrarily.
4. The multilayer optical disc device according to any one of 3.