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Optical recording medium having auxiliary information and reference clock

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Optical recording medium having auxiliary information and reference clock


An information recording medium is composed of a substrate having a microscopic pattern constituted by a continuous substrate of grooves formed with a groove portion and a land portion alternately, a recording layer, and a light transmitting layer. The microscopic pattern is formed with satisfying a relation of P≦λ/NA, wherein P is a pitch of the land portion or the groove portion, λ is a wavelength of reproducing light, and NA is a numerical aperture of an objective lens. The land portion is formed with wobbling so as to be parallel with each other for both sidewalls of the land portion. Auxiliary information and a reference clock is recorded alternately. Information is recorded in the recording layer corresponding to a land portion by either one change of reflectivity difference and refractive index difference in the recording layer.
Related Terms: Numerical Aperture

Browse recent Jvc Kenwood Corporation patents - Kanagawa-ku, JP
Inventors: Tetsuya Kondo, Kenji Oishi
USPTO Applicaton #: #20120269049 - Class: 369 3003 (USPTO) - 10/25/12 - Class 369 
Dynamic Information Storage Or Retrieval > Information Location Or Remote Operator Actuated Control >Selective Addressing Of Storage Medium (e.g., Programmed Access) >Of Optical Storage Medium

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The Patent Description & Claims data below is from USPTO Patent Application 20120269049, Optical recording medium having auxiliary information and reference clock.

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CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of co-pending application Ser. No. 12/652,809, filed on Jan. 1, 2010 (allowed), which is a Continuation of application Ser. No. 11/969,503, filed on Jan. 4, 2008 (now U.S. Pat. No. 7,668,072), which is a Continuation of application Ser. No. 11/620,150, filed on Jan. 5, 2007 (now U.S. Pat. No. 7,336,595), which is a Continuation of application Ser. No. 10/419,149, filed on Apr. 21, 2003 (now U.S. Pat. No. 7,177,162), and for which priority is claimed under 35 U.S.C. §120; and this application claims priority of Application No. 2002-117555 filed in Japan on Apr. 19, 2002 under 35 U.S.C. §119; this application also claims priority of Application No. 2002-141286 filed in Japan on May 16, 2002 under 35 U.S.C. §119; this application also claims priority of Application No. 2002-160129 filed in Japan on May 31, 2002 under 35 U.S.C. §119; this application also claims priority of Application No. 2002-123612 filed in Japan on Apr. 25, 2002 under 35 U.S.C. §119; and this application claims priority of Application No. 2002-148781 filed in Japan on May 23, 2002 under 35 U.S.C. §119; the entire contents of all are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an information recording medium that is particularly used for recording information and a reproducing apparatus for reading out information recorded in the information recording medium with making the information recording medium move relatively, particularly, relates to an information recording medium for recording and/or reproducing information optically and a reproducing apparatus thereof.

2. Description of the Related Art

Until now, there existed a system used for reading out information from an information recording medium while the information recording medium is made relatively move. In order to reproduce the system, such a method as optical, magnetic or capacitance is utilized. A system for recording and/or reproducing information by the optical method has been most popular in daily life. In the case of a read-only type information recording medium in disciform, which is reproduced by a light beam having a wavelength of 650 nm, for example, such a medium in disciform as a DVD video disc pre-recorded with picture image information, a DVD-ROM disc that is pre-recorded with a program or like, a DVD audio disc, or an SACD (Super Audio CD) disc that is pre-recorded with musical information is popularly known.

In the case of a recording and reproducing type information recording medium, there existed a DVD RAM disc utilizing a phase change effect, an ASMO (Advanced Storage Magneto-Optical) disc and an iD (intelligent image disc) utilizing a magneto-optical effect.

On the other hand, in order to increase recording density, such a study as shortening a wavelength of laser beam so as to realize emission of violaceous light has been continued. A second harmonic oscillating element or a semiconductor light emitting element of gallium nitride system compound, which was invented recently, emits light having a wavelength λ in the neighborhood of 350 nm to 450 nm. Consequently, they are possible to be an important light emitting element, which increases recording density drastically.

Further, a design of objective lens complying with such a wavelength has been advanced. Particularly, an objective lens having an NA (numerical aperture) utilized for a DVD disc, that is, an NA of exceeding 0.6 and more than 0.7 is being developed.

As mentioned above, a reproducing apparatus for information recording medium that is equipped with a light emitting element of which wavelength λ is reduced down to 350 nm to 450 nm and equipped with an objective lens of which an NA is more than 0.7 is being developed. By using these technologies, it can be expected that an optical disc system, which surpasses recording capacity of current DVD disc further more, will be developed.

Further, it is also desired that an information recording medium having higher recording density, which is designed on the basis of a violaceous laser beam and a higher NA, is developed.

On the other hand, a recent recording and reproducing type disc adopts a microscopic configuration, namely the land-groove system. With referring to FIGS. 41 and 42, an information recording medium designed for a higher NA recording and reproducing system is explained.

FIG. 41 is a cross sectional view of a conventional information recording medium adopting the microscopic configuration that is called the land-groove system according to the prior art.

FIG. 42 is an enlarged plan view of the information recording medium shown in FIG. 41 showing the horizontal configuration of the information recording medium according to the prior art.

As shown in FIG. 41, an information recording medium 100 is composed of a recording layer 120 and a light transmitting layer 110 that are sequentially laminated on a substrate 130. A microscopic pattern 131 is formed on the substrate 130. The recording layer 120 is formed directly on the surface of the microscopic pattern 131. The microscopic pattern 131 is composed of a plural of land portions “La” and “Lb” (hereinafter generically referred to as land portion “L”) and a plural of groove portions “Ga” to “Gc” (hereinafter generically referred to as groove portion “G”). Macroscopically, the configuration corresponds to that the microscopic pattern 131 is constituted by a continuous groove composed of the land portion “L” and another continuous groove composed of the groove portion “G”.

Further, as shown in FIG. 42, a record mark “M” is formed in both the grooves composed of the land portion “L” and the groove portion “G” respectively when recording.

With paying attention to the dimensions of the microscopic pattern 131, while a shortest distance between the groove portions “Ga” and “Gb” is assumed to be a pitch “P0” (another shortest distance between the land portions “La” and “Lb” is also the pitch “P0”), the microscopic pattern 131 is formed so as to satisfy a relation of P0>S0, wherein “S0” is a spot diameter of reproducing light beam.

Hereupon, the spot diameter “S0” is calculated by a wavelength λ of laser beam for reproducing and an NA of objective lens such as S0=λ/NA. In other words, the pitch “P0” is designed so as to satisfy a relation of P0>λ/NA.

In the case of the information recording medium 100, a light beam for recording (recording light) is irradiated on the light transmitting layer 110 and a record mark “M” is formed on both the land portion “L” and the groove portion “G” of the recording layer 120.

Further, a light beam for reproducing (reproducing light) is irradiated on the substrate 130 or the light transmitting layer 110 and reflected by the recording layer 120, and then the reflected reproducing light is picked up for reproducing.

Inventors of the present invention have actually manufactured an information recording medium 100 as an experiment, and experimentally recorded and reproduced the information recording medium 100. The inventors founded a problem such that a cross erase phenomenon was extremely noticeable. The cross erase phenomenon is a phenomenon such that information is recorded with being superimposed on a signal previously recorded in a groove portion “G”, for example, when recording the information in a land portion “L”. In other words, it is such a phenomenon that information previously recorded in a groove portion “G” is erased by recording another information in a land portion “L”.

Further, this phenomenon can also be noticeable in a reverse case, that is, the cross erase phenomenon is also recognized if previously recorded information in a land portion “L” is observed when recording information in a groove portion “G”. If such a cross erase phenomenon occurs, as mentioned above, information recorded in an adjacent groove is damaged. In case of an information system having larger capacity, an amount of lost information becomes excessively large. Consequently, affection to a user is enormous.

Consequently, it is considered for such an information recording medium 100 that information shall be recorded only in either land portion “L” or groove portion “G”. However, there is existed a problem such that recording capacity of an information recording medium will decrease and a merit of the information recording medium having a potential of recording in higher density will decline if such an information recording method is conducted.

SUMMARY

OF THE INVENTION

Accordingly, in consideration of the above-mentioned problems of the prior art, an object of the present invention is to provide an information recording medium that is reduced in cross erase and can be recorded in higher density, and an reproducing apparatus for reproducing information recorded in the information recording medium with making the information recording medium move relatively.

In order to achieve the above object, the present invention provides, according to an aspect thereof, an information recording medium at least comprising: a substrate having a microscopic pattern constituted by a continuous substrate of grooves formed with a groove portion and a land portion alternately; a recording layer formed on the microscopic pattern for recording information; and a light transmitting layer formed on the recording layer, the information recording medium is further characterized in that the microscopic pattern is formed with satisfying a relation of P≦λ/NA, wherein P is a pitch of the land portion or the groove portion, λ is a wavelength of reproducing light for reproducing the recording layer, and NA is a numerical aperture of an objective lens, and that the land portion is formed with wobbling so as to be parallel with each other for both sidewalls of the land portion, and that an auxiliary information based on data used supplementally when recording the information and a reference clock based on a clock used for controlling a recording speed when recording the information is recorded alternately and continuously.

According to another aspect of the present invention, there provide a reproducing apparatus for reproducing a recording layer of an information recording medium comprising: a substrate having a microscopic pattern constituted by a continuous substrate of grooves formed with a groove portion and a land portion alternately; the recording layer formed on the microscopic pattern for recording information; and a light transmitting layer formed on the recording layer, the information recording medium is further characterized in that the microscopic pattern is formed with satisfying a relation of P≦λ/NA, wherein P is a pitch of the land portion or the groove portion, λ is a wavelength of reproducing light for reproducing the recording layer, and NA is a numerical aperture of an objective lens, and that the land portion is formed with wobbling so as to be parallel with each other for both sidewalls of the land portion, and that an auxiliary information based on data used supplementally when recording the information and a reference clock based on a clock used for controlling a recording speed when recording the information is recorded alternately and continuously, the reproducing apparatus comprising: a light emitting element for emitting reproducing light having a wavelength λ of 350 nm to 450 nm and a noise of less than RIN (Relative Intensity Noise) −125 dB/Hz; a reproducing means equipped with an objective lens having a numerical aperture NA of 0.75 to 0.9; and a control means for controlling the reproducing means to irradiate the reproducing light only on the land portion for reproducing.

Other object and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross sectional view of an information recording medium according to a first embodiment of the present invention.

FIG. 2 is an enlarged plan view of a microscopic pattern of the information recording medium shown in FIG. 1.

FIG. 3 is another enlarged plan view of a microscopic pattern of the information recording medium shown in FIG. 1 exhibiting a state of being recorded.

FIG. 4 is a cross sectional view of the information recording medium shown in FIG. 1 exhibiting a state of reproducing or recording a recording layer of the information recording medium.

FIG. 5 is an enlarged plan view showing an auxiliary information area and a reference clock area in the information recording medium according to the first embodiment, of the present invention.

FIG. 6 is an enlarged plan view of the information recording medium according to the first embodiment of the present invention when information is recorded in the information recording medium through the CLV (Constant Linear Velocity) recording method.

FIG. 7 is an enlarged plan view of the information recording medium according to the first embodiment of the present invention when information is recorded on the information recording medium through the CAV (Constant Angular Velocity) recording method.

FIG. 8 is an enlarged plan view of the information recording medium in disciform according to the first embodiment of the present invention when information is recorded in the information recording medium through the CLV recording method.

FIG. 9 is an enlarged plan view of the information recording medium in disciform according to the first embodiment of the present invention when information is recorded on the information recording medium through the CLV recording method and further the information is recorded on a land portion.

FIG. 10 is an enlarged plan view of a photo-detector mounted on an apparatus for reproducing an information recording medium according to the present invention showing a state of dividing the photo-detector into four.

FIG. 11 is a first example showing a distributed recording of auxiliary information.

FIG. 12 is a second example showing a distributed recording of auxiliary information.

FIG. 13 is a third example showing a distributed recording of auxiliary information.

FIG. 14 is a fourth example showing a distributed recording of auxiliary information.

FIG. 15 is a table exhibiting data change before and after modulating a base-band.

FIG. 16 is a table exhibiting an example of actual data change before and after modulating a base-band.

FIG. 17 shows a first example of an amplitude-shift keying modulation waveform according to the present invention.

FIG. 18 shows a second example of an amplitude-shift keying modulation waveform according to the present invention.

FIG. 19 shows a third example of an amplitude-shift keying modulation waveform according to the present invention.

FIG. 20 shows a first example of a frequency-shift keying modulation waveform according to the present invention.

FIG. 21 shows a second example of a frequency-shift keying modulation waveform according to the present invention.

FIG. 22 shows a third example of a frequency-shift keying modulation waveform according to the present invention.

FIG. 23 shows a first example of a phase-shift keying modulation waveform according to the present invention.



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stats Patent Info
Application #
US 20120269049 A1
Publish Date
10/25/2012
Document #
13459735
File Date
04/30/2012
USPTO Class
369 3003
Other USPTO Classes
3692753, G9B/7029, G9B/7139
International Class
/
Drawings
28


Numerical Aperture


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