JPH02301020A - Multilayer optical disk device - Google Patents

Abstract

PURPOSE:To realize fast access by providing fixed information for tracking on one of recording planes of an optical recording medium, and an optical pickup in which the recording plane different from another optical beam is irradiated with one of plural optical beams, and which performs tracking and the recording and reproduction of data with the optical beam. CONSTITUTION:An optical recording medium D is equipped with a recording layer D1 on which a groove 1 as tracking information is formed, and a layer D2 superimposed on the layer D1 and possible to perform the recording and reproduction of the data 2 on two planes. The layer D1 is comprised similarly as the layer D2 so as to perform the recording and reproduction of the data 2 on the surface of the layer. Meanwhile, the optical beam of the optical pickup is provided with, for example, two beams LB1 and LB2 converged on the groove 1 of the layer D1 on the same optical axis and the boundary plane of the layers D1 and D2, and performs the tracking and the reproduction of the data 2 by capturing the reflected light of the beams. By using such optical recording medium D, it is possible to perform the recording and reproduction of the data 2 on the boundary plane of the second layer D2 as performing the tracking on the first layer D1 with the two optical beams LB1 and LB2.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a multilayer optical disc device.

(Prior Art) In recent years, optical disk devices have been put into practical use, and read-only and write-once types have come to be widely used as memory for document files or computer memory.

Although this optical disk device can record a larger amount of information than a magnetic disk device, such as a hard disk or a floppy disk, an even larger capacity is desired.

Therefore, in order to increase the recording density of optical disks, conventional methods have been to shorten the wavelength of the laser and increase the numerical aperture of the objective lens, but this not only requires the development of elemental parts, but also has a small depth of focus. Therefore, higher precision servo characteristics are required, which is technically difficult and costly.

On the other hand, in order to increase the capacity, a multilayer optical disc device has been proposed in which tracking and data recording/reproduction are performed using a plurality of light beams on an optical recording medium having a structure in which the recording surfaces of optical discs are overlapped.

(Problem to be Solved by the Invention) However, in multilayer optical disc devices that have been proposed in the past, tracking information is provided as fixed information on each recording surface, and the recording surface on which this tracking information is written is Since it was a method for recording and reproducing data, it was necessary to provide tracking information on each recording surface, which caused a problem in that it placed a large burden on the manufacturing process of the optical recording medium.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a multilayer optical disc device that can reduce the burden of the manufacturing process.

[Structure of the Invention] (Means for Solving the Problems) A multilayer optical disc device of the present invention that solves the above problems has the following features:
In a multilayer optical disc device that performs tracking and data recording/reproduction using a plurality of light beams on an optical recording medium having a structure in which a plurality of recording surfaces are stacked, a tracking fixing device is provided on at least one recording surface of the optical recording medium. Information is provided, and at least one of the plurality of light beams irradiates a recording surface different from the other light beams, and an optical pickup is provided that performs tracking and data recording/reproduction using these light beams. shall be.

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

Therefore, fixed tracking information only needs to be provided for one recording surface, and highly accurate positioning is not required for overlapping each recording surface, which reduces the burden on the manufacturing process.

In addition, tracking information can be automatically generated for other recording surfaces one after another by using data recorded on fixedly provided tracking information as new tracking information, so there are no problems during tracking operation. do not have.

(Example) The present invention will be explained in detail below.

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

As shown in the figure, the optical recording medium (optical disk) D of this example is
Recording layer (first
Layer) Dl is overlapped with this layer D1, making it possible to record and reproduce data 2 on both sides! (Second layer > D2. The surface of the first layer D1 is configured to be able to record and reproduce data 2 in the same way as the second layer D2. The thickness of each layer D1 and D2 is set to be the same here. However, what is important is that the error in each thickness is within the depth of focus.

On the other hand, the light beam of the optical pickup passes through the groove 1 of the first MD1, the first layer D1, and the second layer D2 on the same optical axis, for example.
It has two beams LB1.1B2 condensed at the boundary surface of , and by capturing the reflected light, tracking and reproduction of data 2 are performed. The relationship between the relative focusing positions of these two beams LB1.1B2 can be set arbitrarily.

With the above configuration, according to the optical recording medium of this example, two light beams LB1. 11th by LB2! DI groove 1
Data 2 can be recorded and reproduced on the boundary surface of the second WJ while tracking is performed using the second WJ.

Further, as shown in FIG. 2, data 2.4 etc. recorded on one side of the second layer D2 by tracking of groove 1 is used as tracking information, and data 3.5 etc. is recorded and reproduced on the other side. It is possible to record and reproduce data over the entire disk surface by replacing recorded data with tracking information one after another.

In the optical recording medium configured as described above, it is only necessary to provide fixed tracking information on the first layer D1, so there is no need to consider positional deviation in relation to the second layer D2. Its manufacture is easy.

Also, data 2, 3.4°5,
It has a large storage capacity because it can record...

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

As shown in the figure, the optical pickup of this example has two light sources 6
．． 7 and the laser beams LS1.7 output from these light sources 6.7. It is comprised of polarizing plates 9 and 10 that polarize the LB2 and input it to the prism 18, and a lens 11 that focuses the beam projected on the same optical axis by the prism 18 onto a medium. The first beam LB1 is a tracking beam. The second beam LB2 is a beam for recording and reproducing data. The lens 11 is connected to a focusing circuit 12 and a tracking control circuit 13.

On the other hand, the laser beam LB1.1 reflected from the medium
B2 is reflected by the prism 14 to the polarizing prism 15;
The first and second beams are separated into B1 and LB2, and tracking information and data are detected by optical sensors 16 and 17. Sensor 17 is connected to data processing circuit 19 . The tracking control circuit 1
3 and a light source 6 are connected to a recording circuit 20.

With the pickup configured as described above, the focal point on the medium is always set at a predetermined pitch P, and by control of the focusing circuit 12, it is possible to shift the image focal point up and down in the figure.

Furthermore, 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.

Further, by detecting the first laser beam LB1, a tracking control circuit performs tracking processing, and when changing the tracking surface, the focusing circuit can appropriately change the focusing position.

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

In the example of FIG. 3, two beams LB1. Although LB2 is focused on the same optical axis, it is also possible to use two optical axes for $111111. Furthermore, as shown in FIG. 4, it is also possible to adjust the condensing position by controlling the light source position of the beam input to the objective lens 11.

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

The optical recording medium OA shown in FIG. 5 has the first to fourth layers DA1.
．． DA2. DA3. This is an example in which four layers of media consisting of DA4 are stacked and grooves 1 as tracking information are formed on the surface side of the first layer DAI.

In this example, by tracking groove 1, the next IEiDA2
Data can be recorded and reproduced on the recording medium, and data can be recorded and reproduced one after another using the recorded data as tracking data. In the figure, LB is the first or second
The laser beam indicates B1 or LB2.

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

In this example, data can be recorded and reproduced on the upper layer side with respect to 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, the intermediate It! Based on the tracking information of DC3, data can be recorded and reproduced in the upper and lower layers, and data can be recorded and reproduced in the upper or lower layer using the data in the upper or lower layer as new tracking information. I can do it.

In FIG. 8, the optical recording medium DA shown in FIG. 5 is used, the pitch of the focusing points of the tracking laser beam B1 and the data recording/reproducing laser beam LB2 is doubled, and -i
This is an example in which data is recorded and reproduced every other time.

In this example, since the pitch of both beams LB1.1B2 can be changed arbitrarily, data access can be performed quickly.

In the above embodiment, the number of laser beams is two, but the number of beams for data recording and reproduction may be increased, for example, data reproduction may be performed simultaneously on 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, but can be implemented in any appropriate manner by making appropriate design changes.

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

[Brief explanation of drawings]

The drawings all show embodiments of the present invention, with FIG. 1 being an explanatory diagram showing an example of the configuration of a multilayer optical disc, FIG. 2 being an explanatory diagram showing its operation, and FIG. 3 being an explanatory diagram showing an example of the configuration of an optical pickup. Fig. 4 is an explanatory diagram showing another example of the configuration of an optical pickup, Figs. FIG. 3 is an explanatory diagram when the pitch is doubled. 1... Tracking grooves 2-5... Recorded data 12... Focusing circuit 13... Tracking control circuit, DA, DB, DC... Optical recording medium LBI... Tracking laser Beam LB2...Laser beam for data recording/reproduction FIG. 2 FIG. 3 FIG. 4 FIG. 5 FIG. 7 FIG. 6] FIG.

Claims (4)

[Claims] (1) In a multilayer optical disc device that performs tracking and data recording/reproduction using a plurality of light beams on an optical recording medium having a structure in which a plurality of recording surfaces are superimposed, tracking is performed on at least one recording surface of the optical recording medium. an optical pickup is provided which irradiates at least one of the plurality of light beams onto a recording surface different from the other light beams and performs tracking and data recording/reproduction using these light beams. A multilayer optical disc device characterized by: (2) In the multilayer optical disc device according to claim (1), the tracking of the optical pickup includes recording and reproducing data using another light beam using the fixed information for tracking as tracking information. A multilayer optical disc device characterized in that data recorded based on tracking information is used as new tracking information to record and reproduce data. (3) The multilayer optical disc device according to claim (1), wherein the recording surfaces are spaced at equal intervals. (4) The multilayer optical disc device according to claim 1, wherein the light beams are focused on different recording surfaces on the same axis.