CN100347775C - Multi-level read-only optical disc and method of production - Google Patents

Abstract

The present invention relates to a multi-level read-only optical disc and its manufacturing method. The multi-level read-only optical disc has multiple recording pits, and the longitudinal sections of the various recording pits along the width direction of the recording pits are multi-level arbitrary shapes. The area of the longitudinal section of the recording pit is different, and the area of the longitudinal section of the recording pit satisfies the following formula: S=∫h(x)dx, wherein, S represents the area of the longitudinal section of the recording pit, and x represents the width of the recording pit The coordinate of the direction, h(x) represents the pit depth distribution function on the longitudinal section of the recording pit, and the integration area is the entire longitudinal section of the recording pit. In addition, the run length of the multi-stage read-only optical disc can also be limited. The multi-level read-only optical disc with limited run length and its manufacturing method provided by the present invention combine the advantages of multi-level technology and limited run length encoding, and can significantly improve the read-only optical disc without changing the laser wavelength and optical numerical aperture. The optical disc storage capacity and data transfer rate maintain maximum compatibility with the current CD-ROM system.

Description

Multi-stage read-only optical disc and its manufacturing method

technical field

The present invention relates to digital storage technology, more specifically, relates to the digital storage technology using CD-ROM.

Background technique

Existing digital disc products convert information into binary data, and the binary data corresponds to two different physical states of the record symbol of the storage medium in a certain modulation method to realize data storage. This type of storage method is called binary storage. The current read-only optical disc storage technology adopts a binary storage method. According to the intensity of reflected light, it is judged whether the current corresponding position is "Pit" or "Land". Each recording unit Two state numbers can be recorded on it, that is, information corresponding to exactly 1 bit.

Multi-level storage technology is proposed relative to binary storage. If the data stream is modulated into M-ary data (M>2), and the modulated M-ary data corresponds to M different physical states of the recording medium, M-order storage can be realized. M-order storage can store log ₂ (M) bits of data at the position of an information recording spot, so when M is greater than 2, more than 1 bit of information can be recorded on each recording unit, and the data transmission rate is improved at the same time. Multi-level storage is a new technology that can significantly increase storage capacity and data transmission rate without changing the laser wavelength and optical numerical aperture. Therefore, the multi-level storage system has good compatibility with the current optical storage system.

The most basic example of a multi-level read-only optical disc is the multi-level scheme of pit depth modulation, also known as PDM (Pit-Depth Modulation). The principle is that for read-only optical discs, according to the scalar diffraction theory, the light intensity of reflected light has a corresponding relationship with the recording pit depth of the optical disc: starting from the pit depth of 0, as the pit depth increases, the light intensity of reflected light increases with When the pit depth is 1/4 of the laser wavelength, the intensity of the reflected light reaches a minimum value. Utilizing the relationship between the depth of the recorded pit point and the intensity of reflected light, setting different changes in the pit depth can realize multi-level optical disc storage. However, too many orders of disc pit depth will lead to many technical problems, such as disc duplication, signal detection and so on. Therefore, increasing the storage capacity of a read-only optical disc by simply increasing the number of pit depths is relatively limited.

At present, the encoding of multi-level optical disc storage adopts the scheme of amplitude modulation, and the potential of encoding technology has not yet been explored. Conventional binary storage discs all use a run length (referred to as run length) limited encoding scheme, that is, RLL (Run Length Limited, run length limited) encoding. RLL means that the channel sequence stored on the optical disc satisfies the following conditions: there are at least d '0's and at most k '0's between two '1's in the sequence. The two parameters d and k specify the minimum and maximum run lengths that may appear in the sequence, respectively. The parameter d controls the maximum transmission frequency and thus may affect the intersymbol interference when the sequence is transmitted over a band-limited channel. In binary data transmission, it is usually desirable that the received signal is self-synchronizing. Synchronization is usually reproduced using a phase-locked loop. The phase-locked loop adjusts the phase at the detection moment according to the jump of the received waveform. The maximum run length parameter k ensures an appropriate hopping frequency to meet the need for read clock synchronization.

Compared with amplitude modulation coding, RLL coding can improve storage capacity. In binary storage, RLL coding can be used to store more than 1 bit of information on a minimum record, so RLL coding is widely used in optical storage. Such as EFM coding for CD (d=2, k=10) and EFM+ coding for DVD (d=2, k=10). Due to the use of RLL encoding, DVD has obtained a storage density of 1.5 (bit/minimum record character).

Based on the above, there is a need for a multi-level read-only optical disc or master disc and their manufacturing methods that are different from the prior art.

Contents of the invention

In order to overcome at least one defect in the above-mentioned prior art, the object of the present invention is to provide a new type of optical disc that can significantly increase the storage capacity and data transmission rate of the read-only optical disc without changing the laser wavelength and optical numerical aperture. storage technology.

The read-only optical disc adopts a run-limited multi-level storage technology, which can obtain higher storage capacity in the multi-level read-only optical disc with fewer levels.

In order to achieve the above object, the present invention provides a multi-level read-only optical disc, whose track pitch is less than 0.52 microns. Arbitrary shape, the area of the longitudinal section of the recording pit with different orders (different orders) is different, and the area of the longitudinal section of the recording pit satisfies the following formula:

S=∫h(x)dx,

Wherein, S represents the area of the longitudinal section of the recording pit, x represents the coordinates in the width direction of the recording pit, h(x) represents the pit depth distribution function on the longitudinal section of the recording pit, and the integration area is the entire longitudinal section of the recording pit.

In the above-mentioned multi-level read-only optical disc, the area S of the longitudinal section of the pit is determined by the power of the mastering laser.

In the above-mentioned multi-stage read-only CD, its run length (Run Length, run length, referred to as run length) is limited, which can also be called Run Length Limited (Run Length Limited), in the multi-stage read-only CD In the channel sequence, there are at least d "0"s and at most k "0"s between two non-"0" data, where k and d are both integers, k is greater than or equal to d, d is greater than or equal to 0, and the parameter d The minimum run length that may appear in the channel sequence is determined, and the parameter k determines the maximum run length that may appear in the channel sequence.

In the above-mentioned multi-level read-only optical disc, the storage capacity of each record symbol is log ₂ M-bit data, where M is an integer greater than 2 and represents the order number of recording pits.

In the above-mentioned multi-level read-only optical disc, the depths of the recording pits of different orders are different, and the widths of the recording pits of different orders are the same; or, the widths of the recording pits of different orders are different, and the depths of the recording pits of different orders are the same ; Or, the widths of recording pits of different orders are different, and the depths of recording pits of different orders are also different.

In the above multi-level read-only optical disc, the depth and/or width of the recording pits are determined by adjusting the power of the recording laser on the master disc.

In the above-mentioned multi-level read-only optical disc, the longitudinal section of the recording pit along the width direction is multi-stepped with equal height, and the master disc adopts (contains) photoresist material.

In addition, the longitudinal section of the recording pit along the width direction can also be a multi-step shape with different heights. The master disk uses a modified photoresist material. Obtained after physical modification or chemical modification, wherein the physical modification is carried out by at least one treatment method selected from the group consisting of heat treatment, light treatment, electrical treatment, and magnetic treatment, and the chemical modification is performed by increasing at least one additive selected from the group consisting of initiators, sensitizers, and resins.

In addition, the longitudinal section of the recording pit along the width direction can also be of any shape, and the master disk is made of resin material.

In the above-mentioned multi-level read-only optical disc, the run length of the multi-level read-only optical disc is limited. In the channel sequence of the multi-level read-only optical disc, there are at least d "0"s between two non-"0" data, There are at most k "0", wherein, the parameter d determines the minimum run length that may appear in the channel sequence, and the parameter k determines the maximum run length that may appear in the channel sequence.

The present invention also provides a method for making a multi-level read-only master with a track pitch of less than 0.52 microns, comprising the following steps:

a) forming a multi-level coding sequence of binary user data through error correction coding and multi-level modulation coding, generating a write signal for controlling the recording of the master disc, and setting the track pitch of the multi-level read-only master disc to be less than 0.52 microns; as well as

b) Using the write signal generated in step a) to control the power of the recording laser output by the laser, to record the master disc, and generate a multi-level read-only master disc.

In the above-mentioned method for making a multi-level read-only master whose track pitch is less than 0.52 microns, the areas of the longitudinal sections of the recording pits of different orders are different, and the longitudinal sections of the recording pits of the generated multi-level read-only master are different. The cross-sectional area satisfies the following formula:

S=∫h(x)dx,

Wherein, S represents the area of the longitudinal section of the recording pit, x represents the coordinates in the width direction of the recording pit, h (x) represents the pit depth distribution function on the longitudinal section of the recording pit, and the integral area is the area of the recording pit the entire longitudinal section.

In the above method for making a multi-level read-only master with a track pitch of less than 0.52 microns, when the laser is a semiconductor laser, the laser recording power of the semiconductor laser is controlled by adjusting the driving current of the semiconductor laser; when the laser is a gas When using a laser, the laser recording power of the laser is controlled by changing the modulation amplitude of the acousto-optic or electro-optic modulator.

In the above method for making a multi-level read-only master with a track pitch of less than 0.52 microns, the multi-level modulation code is a multi-level run length modulation code, and the formed multi-level code sequence is a multi-order run length code sequence, and the generated The multi-stage read-only master disk of is a multi-stage read-only master disk with limited play length.

In the above-mentioned method for manufacturing a multi-level read-only master disc with a track pitch smaller than 0.52 microns, control of the run length is realized by adjusting the exposure time of the master disc recording laser.

In the above method for making a multi-level read-only master disc with a track pitch less than 0.52 microns, when the laser is a semiconductor laser, the exposure time for recording the master disc is adjusted by adjusting the pulse width of the semiconductor laser drive current; when the laser is a gas When using a laser, the exposure time for mastering is adjusted by adjusting the modulation pulse width of the acousto-optic or electro-optic modulator.

In the above method for making a multi-level read-only master with a track pitch less than 0.52 microns, the longitudinal section of the recording pit along the width direction is multi-step with equal height, and the master disk adopts (contains) photoresist material.

In the above method for making a multi-level read-only master disc with a track pitch of less than 0.52 microns, the longitudinal section of the recording pit along the width direction is multi-stepped with unequal heights, and the master disc is made of modified photoresist Material.

In the above method for making a multi-level read-only master with a track pitch of less than 0.52 microns, the modified photoresist is obtained by physically modifying or chemically modifying the ordinary photoresist used to produce the master, wherein , the physical modification is carried out by at least one treatment mode selected from the group comprising heat treatment, light treatment, electrical treatment, and magnetic treatment, and the chemical modification is carried out by adding at least one of the group selected from the group comprising initiator, sensitizer, and resin An additive is carried out.

In addition, the longitudinal section of the recording pit along the width direction can also be of any shape, and the master disk is made of resin material.

The present invention also provides a method for making a multi-level read-only optical disc with a track pitch of less than 0.52 microns, comprising the following steps:

a) Binary user data is formed into a multi-level coding sequence through error correction coding and multi-level modulation coding to generate a write signal for controlling the recording of the master disc, and the track pitch of the multi-level read-only master disc is set to be less than 0.52 Micron;

b) using the writing signal to control the power of the recording laser output by the laser, and recording the master disc to generate a multi-stage read-only master disc;

c) using the multi-stage read-only master as a mold to reproduce a metal stamper; and

d) Copying a multi-level read-only optical disc by using the stamper.

It can be seen that, compared with the above-mentioned method for manufacturing a multi-level read-only master with a track pitch smaller than 0.52 microns, this method has additional steps c and d.

In the above-mentioned method for making a multi-level read-only optical disc with a track pitch less than 0.52 microns, the areas of the longitudinal sections of the recording pits of different orders are different, and the generated multi-level read-only master and the generated multi-level read-only The area of the longitudinal section of the recording pit of the optical disc all satisfies the following formula:

S=∫h(x)dx,

Wherein, S represents the area of the longitudinal section of the recording pit, x represents the coordinates in the width direction of the recording pit, h(x) represents the pit depth distribution function on the longitudinal section of the recording pit, and the integration area is the entire longitudinal section of the recording pit.

In the above method for making a multi-level read-only optical disc with a track pitch less than 0.52 microns, when the laser is a semiconductor laser, the laser recording power of the semiconductor laser is controlled by adjusting the driving current of the semiconductor laser; when the laser is a gas laser When , the laser recording power of the laser is controlled by changing the modulation amplitude of the acousto-optic or electro-optic modulator.

In the above method for producing a multi-level read-only optical disc with a track pitch less than 0.52 microns, the multi-level modulation coding is a multi-level run-length modulation coding, and the formed multi-level code sequence is a multi-step run-length code sequence, and the generated The multi-level read-only master disc is a multi-level read-only master disc with a limited run length, and the generated multi-level read-only optical disc is a multi-level read-only optical disc with a limited run length.

In the above method for manufacturing a multi-level read-only optical disc with a track pitch smaller than 0.52 microns, the control of the run length is realized by adjusting the exposure time of the master recording laser.

In the above method for producing a multi-level read-only optical disc with a track pitch less than 0.52 microns, when the laser is a semiconductor laser, the exposure time for recording the master disc is adjusted by adjusting the pulse width of the laser drive current; when the laser is a gas When using a laser, the exposure time for recording the master disc is adjusted by adjusting the modulation pulse width of the acousto-optic or electro-optic modulator.

In the above method for manufacturing a multi-level read-only optical disc with a track pitch smaller than 0.52 microns, the longitudinal section of the recording pit along the width direction is multi-stepped with equal height, and the master disc adopts (contains) photoresist material.

In the above method for manufacturing a multi-level read-only optical disc with a track pitch smaller than 0.52 μm, the master disc is made of modified photoresist.

In the above method for producing a multi-level read-only optical disc with a track pitch of less than 0.52 microns, the modified photoresist is obtained by physically or chemically modifying the ordinary photoresist used for producing the master disc, wherein, The physical modification is carried out by at least one treatment selected from the group consisting of heat treatment, light treatment, electrical treatment, and magnetic treatment, and the chemical modification is performed by adding At least one additive is carried out.

In addition, the longitudinal section of the recording pit along the width direction can also be of any shape, and the master disk is made of resin material.

In the multi-level read-only optical disc proposed by the present invention, the track pitch of the recording pits is less than 0.52 microns. The longitudinal section of the recording pit along the width direction, referred to as the longitudinal section of the pit, is one of the following three situations:

1) Equal-height multi-step shape, the depth of the recording pit is the same, but the width is not the same;

2) Multi-step shape with different heights, the width and depth of the recording pits are not the same;

3) Multi-order arbitrary shape, the shape of the recording pit is not fixed, the area of the longitudinal section of the recording pit of different orders is different, the area of the longitudinal section of the pit can be quantitatively expressed by S: S=∫h(x)dx, where , h(x) is the pit depth distribution function on the longitudinal section of the pit, x represents the coordinate in the width direction of the recording pit, and the integration area is the entire recording pit.

The present invention proposes that for the above three situations, different orders of multi-level recording pits can be obtained by changing the power of the recording laser on the master disc, thereby realizing a multi-level read-only optical disc.

The invention also proposes to adopt the RLL coding scheme in the multi-level read-only optical disc, which can further increase the storage density of the read-only optical disc on the basis of multi-level. For example, the storage density of a 4-level optical disc using RLL (d=2, k=8) can reach 2.6 (bit/minimum record symbol), which is equivalent to the storage density of an 8-level optical disc using amplitude modulation. Therefore, the multi-level read-only optical disc adopting RLL can reduce the requirement on the recording pit order of the multi-level read-only optical disc, which is beneficial to the reproduction of the read-only optical disc and the detection of the read signal.

According to the multi-level read-only optical disc of the present invention: on the multi-level read-only optical disc, the track pitch of the recording pits is less than 0.52 microns, and the longitudinal section of the pits is one of the following three situations:

1) Equal-height multi-step shape, the depth of the recording pits is equal, but the width is not the same;

2) Multi-step shape with different heights, the width and depth of the recording pits are not the same;

3) Multi-order arbitrary shape, the shape of the recording pit is not fixed, the area of the longitudinal section of the pit can be quantitatively expressed by S: S=∫h(x)dx, where h(x) is the distribution function of the pit depth on the longitudinal section of the pit , x represents the coordinates in the width direction of the recording pit, and the integration area is the entire recording pit.

In the above situation, the order of the multi-level recording pits is determined by the power of the recording laser on the master disc.

The run length of the multi-level read-only optical disc, that is, the run length (ie run length), is limited: in the channel sequence of the multi-level read-only optical disc, there are at least d "0"s between two non-"0" data , there are at most k "0", and the two parameters d and k respectively determine the minimum and maximum run lengths that may appear in the channel sequence, where k and d are both integers, and k is greater than or equal to d, d greater than or equal to 0.

The method according to the invention comprises the following steps in turn:

Step 1: Put binary user data through error correction coding and multi-order run-length modulation coding, that is, multi-order RLL modulation coding, to form a multi-order run-length coding sequence, generate a signal for controlling the recording and writing of the master disc, and set the master disc recording The track pitch is less than 0.52 microns;

Step 2: Use the writing signal generated in step 1 to control the power of the recording laser output by the laser, and record one of the following three materials: 1) Record the master disc made of photoresist material, generate, etc. 2) recording the master disc made of modified photoresist material to generate a multi-level master disc with unequal height and multi-step shape; 3) pairing the master disc made of resin material Burn the completed master disc to generate a multi-level multi-level master disc of any shape;

The run length in each of the above cases is realized by adjusting the exposure time of master recording: for semiconductor lasers, by adjusting the pulse width of the laser drive current; for gas lasers, by changing the modulation pulse width of the acousto-optic or electro-optic modulator;

For semiconductor lasers, the laser recording power is controlled by adjusting the driving current of the laser. For gas lasers, the laser recording power is controlled by changing the modulation amplitude of the acousto-optic or electro-optic modulator;

Step 3: Using the master disk obtained in step 2 as a mold, copy a metal stamper;

Step 4: Using the stamper obtained in Step 3, the multi-level read-only optical disc with limited play length is reproduced by molding.

In summary, the present invention proposes a run-limited multi-level read-only optical disc storage technology. The width and depth of recording pits of multi-level read-only optical discs are not the same. The present invention proposes to obtain multi-level recording pits with longitudinal sections of arbitrary shapes (different widths and depths, the same width, different depths, or the same depth and the same width, etc.) by changing the power of the mastering laser, thereby realizing Multi-stage CD-ROM.

The invention also proposes the use of the RLL coding scheme in the multi-level read-only optical disc, which can further increase the storage density of the read-only optical disc on the basis of multi-level. For example, the storage density of a 4-level optical disc using RLL (d=2, k=8) can reach 2.6 (bit/minimum record symbol), which is equivalent to the storage density of an 8-level optical disc using amplitude modulation. Therefore, the multi-level read-only optical disc adopting RLL can reduce the requirement on the recording pit order of the multi-level read-only optical disc, which is beneficial to the reproduction of the read-only optical disc and the detection of the read signal.

The multi-level read-only optical disc or master disc with limited run length and the manufacturing method thereof proposed by the present invention combine the advantages of multi-level technology and RLL encoding, and can significantly improve the read-only optical disc without changing the laser wavelength and optical numerical aperture. The optical disc storage capacity and data transfer rate maintain maximum compatibility with the current CD-ROM system. Adopting the RLL coding scheme reduces the requirement on the order of the multi-order read-only optical disc, and is beneficial to the reproduction of the read-only optical disc and the detection of the read signal.

It should be noted that the term "optical disc" mentioned herein should be understood from the perspective of those skilled in the art to include a "sub-disc" (commonly known as an optical disc) and a "master disc". The "optical disk" in the product claims covers both the "sub-disc" and the "master disc", because the structures of the "sub-disc" and "master disc" sought to be protected by the present invention are the same. However, in the method claim, since the production method of the "master disc" is different from that of the "sub-disc", specifically, the production of the "sub-disc" first requires the production of the "master disc", so in the method claim In the requirements, "disc" refers to "subdisk".

Description of drawings

In order to better understand the present invention, the following will be described with reference to the accompanying drawings according to specific embodiments of the present invention, in the accompanying drawings:

Fig. 1 shows the multi-stage RLL master disc burning process and the master disc profile after burning;

Fig. 2 shows multi-stage RLL encoding and write signal waveform generation process;

Figure 3a shows the recording process of the multi-stage RLL master disc of photoresist material and the top view of the master disc after recording;

Figure 3b shows the recording process of the multi-stage RLL master disc of photoresist material and the longitudinal section view of the master disc after recording (equal height ladder shape);

Figure 4a shows the recording process of the multi-stage RLL master disc of the modified photoresist material and the cross-sectional view of the master disc after recording;

Figure 4b shows the recording process of the multi-stage RLL master disc of the modified photoresist material and the top view of the master disc after recording;

Figure 4c shows the longitudinal section of the multi-level RLL master disk recording pit of the modified photoresist material (different high-level ladder shape);

Figure 5a shows the recording process of the multi-stage RLL master disc of resin material and the cross-sectional view of the master disc after recording;

Figure 5b shows the recording process of the multi-stage RLL master disc of resin material and the top view of the master disc after recording;

Fig. 5c shows the longitudinal section of the recording pit of the multi-stage RLL master disk of resin material (multi-stage arbitrary shape);

Figure 6a shows a top view of the multi-stage RLL read-only optical disc replication process in which the master disc is a photoresist material;

Figure 6b shows a longitudinal sectional view of a multi-stage RLL read-only optical disc replication process in which the master disc is a photoresist material;

Figure 7a shows a cross-sectional view of the multi-stage RLL read-only optical disc replication process in which the master disc is a modified photoresist material;

Figure 7b shows a top view of the replication process of a multi-stage RLL read-only optical disc in which the master disc is a modified photoresist material;

Figure 7c shows a longitudinal sectional view of the replication process of a multi-stage RLL read-only optical disc whose master disc is a modified photoresist material;

Fig. 8 a shows the cross-sectional view of the multi-stage RLL read-only optical disc duplication process in which the master disc is a resin material;

Fig. 8 b shows the recording pit longitudinal section (multi-order arbitrary shape) of the multi-stage RLL read-only optical disc replication process in which the master disc is a resin material;

Fig. 9 shows that the master disk is the read-out waveform (top view) of the multi-stage RLL read-only optical disk of photoresist material;

Fig. 10 shows that master disk is the read-out waveform (sectional view) of the multi-stage RLL read-only optical disk of modified photoresist material;

Fig. 11 shows the read-out waveform (sectional view) of a multi-stage RLL read-only optical disc whose master disc is a resin material;

Fig. 12 shows a schematic diagram (top view) of a 4-stage RLL read-only optical disc embodiment in which the master disc is a photoresist material;

Fig. 13 shows a schematic diagram (sectional view) of a 4-stage RLL read-only optical disc embodiment in which the master disc is a modified photoresist material;

Fig. 14 shows the schematic diagram (sectional view) of the embodiment of the 4-stage RLL read-only optical disc whose master disc is a resin material;

Figure 15 shows a flow chart of the method for making a multi-level read-only master disc according to the present invention; and

FIG. 16 shows a flowchart of a method for making a multi-stage read-only optical disc according to the present invention.

Detailed ways

In the production process of optical disc, generally first make master disc, the step of making master disc comprises: coating one deck master disc photoresist on glass substrate (in the present invention, the model that adopts British Rohm & Haas is Microposit S1800-4 photoresist), use the master disc recording system (in the present invention, the ∏ mastering System of England NIMBUS) to record the master disc, adopt the laser of NLHV 500C model of Nichia, Japan) to expose the photoresist, and develop, Create a master disc.

Then, use this master disc as a mould, use a glass disc sputtering machine (in the present invention, adopt the model of Swiss UNAXIS to be the sputtering machine of Pyramet) glass substrate is carried out sputtering (sputtering process), coat a layer A thinner metal layer is then plated with a relatively thicker metal layer to obtain a metal negative image sub-disc, which can be used as a stamper for injection molding replication. In the present invention, the DVD disc production line produced by Panasonic Corporation of Japan is adopted. Use injection molding machine (in the present invention, adopt the DL0004 type and DR0004 type vertical injection molding machine of Panasonic Corporation of Japan) to press the disk, then use the SWIVEL type or CUBLITE type sputtering machine of Switzerland UNAXIS to sputter the pressed disk , and finally, use a stamper to emboss the disc. The completion line adopts the GRBA-151 system of Panasonic Corporation of Japan. The online detector adopts the S3DVD online detector of BASLER in Germany.

In addition, the master disc/sub disc tester uses the DVDStamper Pro or ST3 Stamper Pro from Audio Dev in Sweden. The disk testing instrument uses O-PAS 1000 or DDU 1000 from Japan Pulstec.

The recording of the master disc of the multi-stage read-only optical disc is realized by changing the power of recording laser. There are two schemes for obtaining different power recording lasers: scheme 1) for semiconductor lasers, different output powers can be obtained by adjusting the driving current of the laser; scheme 2) for gas lasers, by changing the acousto-optic (or electro-optic) modulator Modulate the amplitude to obtain different output powers. Different laser powers can record different multi-level recording pits on the following three materials:

1) Photoresist material, equal-height multi-step multi-level recording pit;

2) Modified photoresist material, multi-step recording pits with different heights;

3) Resin material, arbitrary shape multi-level recording pit.

While controlling the recording laser power, multi-level recording pits with different run lengths are obtained by adjusting the exposure time, thereby realizing a multi-level read-only optical disc with a limited run length. There are also two schemes for adjusting the exposure time of master recording: scheme 1) for semiconductor lasers, different exposure times can be obtained by adjusting the pulse width of the laser drive current; scheme 2) for gas lasers, by changing the acousto-optic (or The modulated pulse width of the electro-optic) modulator to obtain different exposure times.

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a multi-stage RLL master disc recording process and a cross-sectional view of the master disc after recording, which is a schematic diagram of the present invention.

The specific implementation plan of the multi-stage read-only optical disc master disc with limited travel length and track pitch less than 0.52 microns proposed by the present invention is as follows: set the track pitch of the recording pits to be less than 0.52 microns, select one of the following three materials, and use different Recording laser power, can record different multi-level recording pits respectively:

1) Photoresist material, equal-height multi-step multi-level recording pits, the depth of the recording pits is equal, but the width is not the same;

2) Modified photoresist material, multi-step recording pits with different heights, and the depth and width of the recording pits are different;

3) Resin material, arbitrarily shaped multi-stage recording pits, the areas of the longitudinal sections of the recording pits of different orders are different.

Fig. 2 shows the process of multi-stage RLL encoding and writing signal waveform generation.

The modulation coding adopted in the present invention is multi-stage RLL coding, as can be seen from Fig. 2, at first, input error correction coder 204 with binary user data 202, generate the binary sequence 206 that comprises user data and check code; Then The binary sequence 206 is input into a multi-stage RLL encoder 208 to generate a multi-stage (d, k) run-length sequence 210, which satisfies the following condition: there are at least d '0's between two non-'0' data in the sequence , there are at most k '0's, and the two parameters d and k respectively specify the minimum and maximum run lengths that may appear in the sequence; finally, the sequence is generated by the NRZI conversion operation 212 of modulo M to control the recording of the master disc The signal waveform 214 is written.

In the master recording of photoresist material, the recording process is realized by the photochemical effect of the material. Under the action of the recording laser, the photoresist on the exposed part of the master disc undergoes a photochemical reaction, and after developing and fixing, a recording pit is formed on the exposed part. The power of the recording laser is controlled by the amplitude of the write signal waveform. Different laser powers correspond to different recording pit widths for different orders, but the pit depths are the same. The photoresist material is generally used in the current master recording system, so it is more suitable for the current master production system.

In the recording of the master disc of the modified photoresist material, the recording process is realized by the photochemical effect of the material. Under the action of the recording laser, the modified photoresist on the exposed part of the master disc undergoes a photochemical reaction, and after developing and fixing, a recording pit is formed on the exposed part. The photochemical reaction speed of the unmodified photoresist is fast, and the photoresist at the exposed part reacts, so the depth of the recording pit is the same; the photochemical reaction speed of the modified photoresist slows down, and the modified photoresist that reacts at the exposed part The depth of the resist depends on the exposure power, and different exposure powers can obtain recording pits with different depths. The power of the recording laser is controlled by the amplitude of the writing signal waveform. Different laser powers correspond to different order recording pit widths and depths. This increases the resolution between recording pits of different orders, which is beneficial to Reproduction of CD-ROMs and detection of read signals. Photoresist materials are widely used in the current master recording system, and the modified photoresist based on this is also easy to realize, so the modified photoresist is more suitable for the current master production system.

In the recording of the master disc of the resin material, the recording process is realized by the thermal effect of the laser. Under the heat effect of the recording laser, the resin material in the exposed part of the master disc is vaporized, thereby directly forming a recording pit. The power of the recording laser is controlled by the amplitude of the writing signal waveform. Different laser powers have different widths and depths corresponding to recording pits of different orders. This increases the resolution between recording pits of different orders, which is beneficial to only Read copying of optical discs and detection of read signals.

While the amplitude of the write signal waveform (write waveform) controls the laser power, the length of the write signal waveform controls the switching time of the laser or modulator, thereby obtaining multi-level recording pits with different run lengths. That is to say, the amplitude and length of the write signal waveform respectively control the power and exposure time of the recording laser, and finally control the order and run length of the recording pits, so as to realize the multi-level read-only optical disc with limited run length. Master disk (Master) burning. The recording process of the multi-stage RLL master disc and the schematic diagram of the master disc after recording are shown in Fig. 3a-b, Fig. 4a-c, and Fig. 5a-c.

After obtaining the multi-stage RLL master disk, use this master disk as a mold, and through the spraying process, obtain a metal negative image sub-disk, which can be used as a stamper for injection molding replication. Using the Stamper as a stamper, through Injection molding, it is possible to reproduce the CD-ROM of the multi-level RLL. This replication process is shown in Figures 6a-b, Figures 7a-c, and Figures 8a-b.

See Fig. 9, Fig. 10 and Fig. 11 for the read-out process of the multi-stage RLL read-only optical disc. The optical read-out system of the multi-stage RLL read-only optical disc is fully compatible with the optical read-out system of the conventional read-only optical disc, so the optical read-out system of the conventional read-only optical disc can be used to read the multi-stage RLL read-only optical disc. The read-out waveforms of multi-stage RLL read-only optical discs are shown in Figure 9, Figure 10, and Figure 11. The amplitude of the read signal is determined by the order of the recording pit (also known as the order), starting from the order of 0, as the recording pit As the order of the pits increases, the intensity of the reflected light decreases, and the intensity of the reflected light reaches a minimum at the highest-order recording pit. The length of a readout signal of a specific amplitude is determined by the run lengths of pits of different orders. According to the readout waveform, the multi-order (d, k) sequence written in Fig. 1 can be restored by specific modulo operation. The read-out waveforms of the multi-stage RLL read-only optical disc are shown in Fig. 9, Fig. 10 and Fig. 11 .

Below will further illustrate content of the present invention by embodiment, but content of the present invention is not limited to described in embodiment:

According to the multi-stage read-only optical disc technology with limited run length proposed by the present invention, we have designed a 4-stage RLL read-only optical disc, the schematic diagrams of which are shown in FIG. 12 , FIG. 13 , and FIG. 14 . First, the binary sequence generated by binary user data is input to the 4th-order RLL modulation encoder to generate a 4th-order (d, k) sequence, here we select (d=2, k=10).

This sequence generates the write signal waveform to control master recording through [a(n-1)+b(n)]mod 4=a(n), where a(n) is the write level of the nth sequence , b(n) is the nth data in the 4-order RLL sequence, and M is the order number of the multi-order disc. For example, the level a(4) of the 4th sequence of the written signal waveform in the figure is 0, and the 5th data b(5)=2 of the 4th-order RLL sequence, through the modulo budget (0+2) mod4=2 , the level a(5) of the fifth sequence of the write signal waveform can be obtained as 2.

Under the control of the write signal waveform, the write laser can write different multi-level recording pits on the following three materials:

1) Photoresist material, equal-height multi-step multi-level recording pits, the depth of the recording pits is the same, but the width is not the same;

2) Modified photoresist material, multi-step recording pits with different heights, and the depth and width of the recording pits are different;

3) Resin material, arbitrarily shaped and multi-stage recording pits, and the areas of the longitudinal sections of the pits are different.

Referring to FIG. 12 , FIG. 13 , and FIG. 14 , the write signal waveform also controls the run length of these multi-level recording pits. After obtaining the 4-stage RLL master disc, use this master disc as a mold and undergo a spraying process to obtain a metal stamper (Stamper). Using the stamper as a stamper, the 4-stage RLL can be copied by injection molding CD-ROM.

The read-only optical disc of the conventional read-only optical disc is used to read the 4-stage RLL read-only optical disc. The amplitude of the readout signal is determined by the order of the recording pits, and the length of the readout signal is determined by the run lengths of the recording pits of different orders. Based on the read waveform, the written multi-level (d, k) sequence can be restored by the following modulo operation.

$b\left(\mathrm{no}\right)=\left\{\begin{array}{c}\mathrm{\&Delta;a},\mathrm{\&Delta;a}\&Greater\; Equal;0\\ \mathrm{\&Delta;a}+m,\mathrm{\&Delta;a}<0\end{array}\right.,$ where Δa=a(n-1)-a(n)

For example, the 4th level a(4)=3 and the 5th level a(5)=1 of the waveform read out in the figure, through the modulo operation 2=(3-1), the b(5 )=2, which coincides with the fifth data in the written (d, k) sequence.

Through the whole process of Fig. 12, Fig. 13, and Fig. 14, the whole process of data generation, master recording, duplication and signal reading of the multi-stage RLL read-only optical disc is realized.

Through the above, the present invention summarizes the manufacturing methods of the multi-level read-only optical disc and the master disc, as shown in Fig. 15 and Fig. 16 respectively.

Fig. 15 shows a flowchart of a method for making a multi-level read-only master according to the invention. The method includes the following sequential steps:

Step 1502, form the binary user data into a multi-level coding sequence through error correction coding and multi-level modulation coding, and generate a writing signal for controlling the recording of the master disc; and

Step 1504, using the writing signal to control the power of the recording laser output by the laser to record the master disk to generate a multi-level read-only master disk.

In the above method for making a multi-level read-only master with a track pitch of less than 0.52 microns, the area of the longitudinal section of the recording pit of the generated multi-level read-only master satisfies the following formula:

S=∫h(x)dx,

Wherein, S represents the area of the longitudinal section of the recording pit, x represents the coordinates in the width direction of the recording pit, h (x) represents the pit depth distribution function on the longitudinal section of the recording pit, and the integral area is the area of the recording pit the entire longitudinal section. Those skilled in the art should understand that the pit depth distribution function can be selected arbitrarily, so no illustration will be given herein.

In the above method for making a multi-level read-only master with a track pitch of less than 0.52 microns, when the laser is a semiconductor laser, the laser recording power of the semiconductor laser is controlled by adjusting the driving current of the semiconductor laser; when the laser is a gas When using a laser, the laser recording power of the laser is controlled by changing the modulation amplitude of the acousto-optic or electro-optic modulator.

In the above method for making a multi-level read-only master with a track pitch of less than 0.52 microns, the multi-level modulation code is a multi-level run length modulation code, and the formed multi-level code sequence is a multi-order run length code sequence, and the generated The multi-stage read-only master disk of is a multi-stage read-only master disk with limited play length.

In the above-mentioned method for manufacturing a multi-level read-only master disc with a track pitch smaller than 0.52 microns, control of the run length is realized by adjusting the exposure time of the master disc recording laser.

In the above method for making a multi-level read-only master disc with a track pitch less than 0.52 microns, when the laser is a semiconductor laser, the exposure time for recording the master disc is adjusted by adjusting the pulse width of the semiconductor laser drive current; when the laser is a gas When using a laser, the exposure time for mastering is adjusted by adjusting the modulation pulse width of the acousto-optic or electro-optic modulator.

In the above method for making a multi-level read-only master disc with a track pitch of less than 0.52 microns, the longitudinal section of the recording pit along the width direction is multi-stepped with unequal heights, and the master disc is made of modified photoresist .

In the above method for making a multi-level read-only master with a track pitch of less than 0.52 microns, the modified photoresist is obtained by physically modifying or chemically modifying the ordinary photoresist used to produce the master, wherein , the physical modification is carried out by at least one treatment mode selected from the group comprising heat treatment, light treatment, electrical treatment, and magnetic treatment, and the chemical modification is carried out by adding at least one of the group selected from the group comprising initiator, sensitizer, and resin An additive is carried out.

In the above method for manufacturing a multi-level read-only master disc with a track pitch less than 0.52 microns, the longitudinal section of the recording pit along the width direction is multi-step with equal height, and the master disc is made of common photoresist material.

In the above-mentioned method for manufacturing a multi-level read-only master disc with a track pitch smaller than 0.52 microns, the longitudinal section of the recording pit along the width direction has an arbitrary shape, and the master disc is made of resin material.

Fig. 16 shows a flowchart of a method for making a multi-stage read-only optical disc according to the invention. The method includes the following sequential steps:

Step 1602, the binary user data is formed into a multi-level coding sequence through error correction coding and multi-level modulation coding, and generates a write signal for controlling the recording of the master disc;

Step 1604, use the writing signal to control the power of the recording laser output by the laser, and record the master disc to generate a multi-level read-only master disc;

Step 1606, using the multi-level read-only master disk as a mold, copying a metal stamper; and

Step 1608, use the stamper to copy the multi-level read-only optical disc by molding.

Compared with the method for making a multi-level read-only master disc shown in FIG. 15 , the method for making a multi-level read-only optical disc shown in FIG. 16 has more steps 1606 and 1608 .

In the above-mentioned method for making a multi-level read-only optical disc with a track pitch less than 0.52 microns, the areas of the longitudinal section of the generated multi-level read-only master and the recording pits of the generated multi-level read-only optical disc all satisfy the following formula:

S=∫h(x)dx,

Wherein, S represents the area of the longitudinal section of the recording pit, h(x) represents the pit depth distribution function on the longitudinal section of the recording pit, x represents the coordinate in the width direction of the recording pit, and the integration area is the entire longitudinal section of the recording pit.

In the above method for making a multi-level read-only optical disc with a track pitch less than 0.52 microns, when the laser is a semiconductor laser, the laser recording power of the semiconductor laser is controlled by adjusting the driving current of the semiconductor laser; when the laser is a gas laser When , the laser recording power of the laser is controlled by changing the modulation amplitude of the acousto-optic or electro-optic modulator.

In the above method for producing a multi-level read-only optical disc with a track pitch less than 0.52 microns, the multi-level modulation coding is a multi-level run-length modulation coding, and the formed multi-level code sequence is a multi-step run-length code sequence, and the generated The multi-level read-only master disc is a multi-level read-only master disc with a limited run length, and the generated multi-level read-only optical disc is a multi-level read-only optical disc with a limited run length.

In the above method for manufacturing a multi-level read-only optical disc with a track pitch smaller than 0.52 microns, the control of the run length is realized by adjusting the exposure time of the master recording laser.

In the above method for producing a multi-level read-only optical disc with a track pitch less than 0.52 microns, when the laser is a semiconductor laser, the exposure time for recording the master disc is adjusted by adjusting the pulse width of the laser drive current; when the laser is a gas When using a laser, the exposure time for recording the master disc is adjusted by adjusting the modulation pulse width of the acousto-optic or electro-optic modulator.

In the above method for manufacturing a multi-level read-only optical disc with a track pitch less than 0.52 microns, the longitudinal section of the recording pit along the width direction is multi-stepped with unequal height, and the master disc is made of modified photoresist.

In the above method for producing a multi-level read-only optical disc with a track pitch of less than 0.52 microns, the modified photoresist is obtained by physically or chemically modifying the ordinary photoresist used for producing the master disc, wherein, The physical modification is carried out by at least one treatment selected from the group consisting of heat treatment, light treatment, electrical treatment, and magnetic treatment, and the chemical modification is performed by adding At least one additive is carried out.

In the above-mentioned method for manufacturing a multi-level read-only optical disc with a track pitch less than 0.52 microns, the vertical section of the recording pit along the width direction is multi-stepped with equal height, and the master disc is made of common photoresist material.

In the above method for manufacturing a multi-level read-only optical disc with a track pitch smaller than 0.52 microns, the longitudinal section of the recording pit along the width direction has an arbitrary shape, and the master disc is made of resin material.

In summary, the multi-level read-only optical disc or master disc with limited run length and its manufacturing method proposed by the present invention combine the advantages of multi-level technology and RLL coding, and can significantly Improve the CD-ROM storage capacity and data transfer rate, and maintain maximum compatibility with the current CD-ROM system. Adopting the RLL coding scheme reduces the requirement on the order of the multi-order read-only optical disc, and is beneficial to the reproduction of the read-only optical disc and the detection of the read signal.

In addition, those skilled in the art should understand that when the present invention is used to make Blu-ray discs, the track pitch can be limited to less than 0.52 microns, or less than 0.5 microns or less, such as less than 0.45 microns or 0.4 microns.

It should be noted that the term "optical disc" mentioned herein should be understood from the perspective of those skilled in the art to include a "sub-disc" (commonly known as an optical disc) and a "master disc". The "optical disk" in the product claims covers both the "sub-disc" and the "master disc", because the structure of the "sub-disc" and the "master disc" sought to be protected by the present invention are the same. However, in the method claim, since the production method of the "master disc" is different from that of the "sub-disc", specifically, the production of the "sub-disc" first requires the production of the "master disc", so in the method claim , "disc" refers to "subdisk".

Furthermore, for the purpose of illustration, this paper discloses the specific manufacturers and models of many devices, equipment, or systems used to realize the present invention, but those skilled in the art should understand that this is not intended to limit the present invention, and other Products of other models of manufacturers can also implement the present invention.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (11)

1. multistep read-only optical disk, it is characterized in that, the track pitch of described multistep read-only optical disk is less than 0.52 micron, described multistep read-only optical disk has multiple record pit, the longitudinal section of described record pit is multistage arbitrary shape, the area of the longitudinal section of the record pit of different rank has nothing in common with each other, and the area of the longitudinal section of described record pit satisfies following formula:

S＝∫h(x)dx，

Wherein, S represents the area of the longitudinal section of described record pit, and x represents the coordinate of record pit Width, the dark distribution function in hole on the longitudinal section of the described record pit of h (x) expression, and integral domain is the whole longitudinal section of described record pit.

2. multistep read-only optical disk according to claim 1 is characterized in that, the area S of longitudinal section, described hole is by the power decision of mother CD burning laser.

3. multistep read-only optical disk according to claim 1, it is characterized in that the brigade commander of described multistep read-only optical disk is limited, in the passage sequence of described multistep read-only optical disk, between two non-" 0 " data the rarest d " 0 ", k " 0 " is arranged at most, and wherein, k, d are integer, k is more than or equal to d, d is more than or equal to 0, and parameter d has determined to appear at the minimum brigade commander in the described passage sequence, and parameter k has determined to appear at the maximum brigade commander in the described passage sequence.

4. multistep read-only optical disk according to claim 1 is characterized in that, the degree of depth difference of the record pit of different rank.

5. multistep read-only optical disk according to claim 1 is characterized in that, the width difference of the record pit of different rank.

6. multistep read-only optical disk according to claim 1 is characterized in that, the width difference of the record pit of different rank, the degree of depth of the record pit of different rank are also different.

7. according to each described multistep read-only optical disk in the claim 4 to 6, it is characterized in that, determine the degree of depth and/or the width of described record pit by the power of regulating stamper disc imprinting laser.

8. multistep read-only optical disk according to claim 7 is characterized in that, the longitudinal section of described record pit broad ways is contour multistage trapezoidal, and described stamper disc adopts the photoresist material.

9. multistep read-only optical disk according to claim 7 is characterized in that, the longitudinal section of described record pit broad ways is not contour multistage trapezoidal, and described stamper disc adopts modification photoresist material.

10. multistep read-only optical disk according to claim 9, it is characterized in that, described modification photoresist is to obtain after the common photoresist that the production stamper is used is passed through physical modification or chemical modification, wherein, described physical modification is undertaken by at least a processing mode that is selected from the group that comprises thermal treatment, optical processing, electric treatment and magnetic treatment, and described chemical modification is selected from the group that comprises initiating agent, sensitizer and resin by increase at least a adjuvant carries out.

11. multistep read-only optical disk according to claim 7 is characterized in that, the longitudinal section of described record pit broad ways is an arbitrary shape, and described stamper disc adopts resin material.

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