WO2002099802A1 - Method for indicating a sector on a data medium and data medium adapted to said method - Google Patents

Method for indicating a sector on a data medium and data medium adapted to said method

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Publication number
WO2002099802A1
WO2002099802A1 PCT/FR2002/001836 FR0201836W WO02099802A1 WO 2002099802 A1 WO2002099802 A1 WO 2002099802A1 FR 0201836 W FR0201836 W FR 0201836W WO 02099802 A1 WO02099802 A1 WO 02099802A1
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WO
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Patent type
Prior art keywords
byte
binary
vector
head
groove
Prior art date
Application number
PCT/FR2002/001836
Other languages
French (fr)
Inventor
Philippe Graffouliere
Original Assignee
Stmicroelectronics S.A.
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Filing date
Publication date

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Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/19Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
    • G11B27/24Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by sensing features on the record carrier other than the transducing track ; sensing signals or marks recorded by another method than the main recording
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10Digital recording or reproducing
    • G11B20/10009Improvement or modification of read or write signals
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10Digital recording or reproducing
    • G11B20/14Digital recording or reproducing using self-clocking codes
    • G11B20/1403Digital recording or reproducing using self-clocking codes characterised by the use of two levels
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/19Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/007Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/007Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
    • G11B7/00745Sectoring or header formats within a track
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00Record carriers by type
    • G11B2220/20Disc-shaped record carriers
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/19Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
    • G11B27/28Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording
    • G11B27/30Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording
    • G11B27/3027Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording used signal is digitally coded

Abstract

The invention concerns a method for indicating on a data medium (9) a sector referenced by a binary word (16) consisting of M number of multiplets comprising each L number of bits, comprising operations which consist in engraving on the data medium locally at said sector, a succession of M multiplets corresponding each to a first multiplet, each second multiplet being equal to a vector of N components, each of value +1 or -1, such that N = 2L- 1 and such that the scalar product of said vector by any other vector to which is equal another second multiplet, is not more than a + 1. The data medium (9) is for example an optical disc.

Description

PROCESS TO INDICATE AN AREA ON A CARRIER

INFORMATION AND INFORMATION SUPPORT

ADAPTED TO THE METHOD

The field of the invention is that of information recordable media such as optical disks and especially information carriers on which information registration is distributed by sectors. In the context of the invention, each sector is referenced by a binary word previously engraved on the information carrier. Thus, to access a sector, a read head or write scans the information medium to detect this binary word.

Generally, a blank optical disc is not completely blank. A recording track is pre stamped on the disc. Often, this track is embodied by a spiral groove whose depth is equal to a quarter wavelength of laser beam emitted from a pickup. During a write on the disc, the read head follows the groove so as to maintain a writing laser beam within, near or alternately inside and outside the groove.

The groove is shaped like a spiral on a macroscopic scale and a sinusoidal shape (called wobble in English) on a microscopic scale. The sinusoidal shape is mainly used for measuring a linear velocity of the disk passing under the read head so as to control this speed. In a first known prior art, a series of pre-positioned holes (called prepit English) locally in each sector materializes the binary word that reference this sector. These holes are pre-positioned within or near the groove so as to detect an absolute position of the sector by means of the reading head when it follows the groove. The frequency at which pass the succession of pre holes positioned under the read head, makes this encoding mode is particularly sensitive to high frequency noise. This sensitivity to noise is generating errors on decoding the succession of pre holes positioned to get the binary word that references the sector. Another solution is to encode the binary word by modifying certain cycles of the sinusoidal shape of the groove. For example, a modified alternating represents a first binary value and vice versa a conserved alternating represents a second binary value complementary to the first. The alternating changes should be made so as not to disturb the detection of the original by alternating the reading head in its servo functions to follow the groove and to calculate the drive running speed in the head.

Writing data on the disc, such as NRZ data (non-reset), is usually made by power modulation of the laser beam to a write head adjacent the tape head. When reading the resulting signal of alternating changes made during a writing data to the disk, the read signal on the disc is disturbed by the writing laser beam. This is error-prone on the decoding of alternating changes to the binary word that references the sector which are scheduled to be written data to be recorded.

In order to write data to the right area as planned, it should overcome the errors for decoding the binary word that references the sector.

One could envisage a solution which involves placing an analog circuit between the read head and the decoding circuit, to filter the disturbances caused by modulating power of the writing laser beam. However, this solution integration disadvantages when you want to reduce the clutter of electrical circuits in a read-write block on an optical disc. The logic circuits allow to obtain high integration easier than analog circuits.

To respond to the problem, a first object of the invention is a method to indicate on an information carrier, an area referenced by a binary word consisting of M number of first bytes each comprising a number L bits. The method is characterized in that it comprises the actions of etching on the recording medium locally to the sector, a series of M second bytes each corresponding to a first byte, second byte each being equal to a vector of N components each of value +1 or -1, such that N = 2 L - 1 and such that the inner product of said vector with any vector which can otherwise equals another second byte, is at most equal to 1. The two values ​​+1 and -1 taken as first and second binary value, have the effect of obtaining a scalar product equal to N when the vector is multiplied by itself. The decoding for the binary word that references a sector is then achieved by a simple logic circuit. Simply match each second byte detected by a reading head, a first byte. The binary word reference then direct result of a concatenation of the first bytes obtained. In the absence of read error of the second byte, the second byte is easily recognizable because it is the one whose scalar square is equal to N, greater than 1, the scalar product by other bytes being limited to 1. In the presence read errors on some bits of the second byte, the second byte remains easily recognizable because it is the one whose scalar square is the closest N, the other scalar products being inferior to him. So just to match the first byte in the second byte whose scalar product with the second byte is detected the greater value.

Different routes for etching the succession of second bytes, are conceivable.

Advantageously, the method according to the invention is further characterized in that one of the values ​​+1 or -1 is etched by changing an amplitude of a wobble period of a groove on the information carrier.

For example, the amplitude is increased to be one of binary values ​​and stored to represent the other binary value. It is thus possible to use the groove for second bytes without changing the oscillation period. This maintains the qualities of the groove which remains centered on the same average value for the position control of the read head and remains the same frequency for the servo speed of the information carrier.

The various possibilities are not limited to that previously stated. Differently, the method is also advantageous when it is characterized in that one of the values ​​+1 or -1 is etched by adding on an initial ripple period of a groove on the recording medium, three cycles of frequency three times larger than an initial frequency of undulation of said groove.

Again, the undulations of the groove remain centered around the mean value of the initial waves. This does not affect the speed of assessment since it is mainly sensitive to a frequency three times less. If the amplitude of the added sine oscillation is equal to half the amplitude of the basic sine oscillation, only one zero-crossing is observed in the center of a base period. When the total resultant amplitude is not changed, the entire space of the recording medium out of the initial wobbling of the groove, still available for writing data to be recorded.

To a lesser amount of sectors on the information carrier, it is possible to choose the number M of first bytes, equal to one, within the scope of the invention. The number L is equal to the number of bits of the binary word that reference each area. Dividing the binary word into at least two first bytes each comprising a number L of bits, at most equal to half the number of bits of the binary word, one reduces the size of each second byte in a substantially quadratic proportion. A size of the succession of M second bytes, less than the number of oscillations of the groove over a sector, allows the use of all or part of the remaining oscillations to improve the recognition of each sector.

According to an additional characteristic of the process, a third byte of said synchronization, is added to the head of the sequence of M second bytes, said sync byte consisting of a acyclic sequence of P bits with P greater than N.

The sync byte provides the advantage of accurately detect the start of the succession of M second bytes, and therefore the beginning of the referenced sector, thus allowing to use the sector at full capacity. By choosing for the sync byte, an acyclic sequence of P bits with P greater than N, it provides synchronization, even with a high error rate while decreasing the risk of confusion with a second byte. One can consider options for associating with each value of the first byte, a vector with N components, such as its scalar product with any other vector associated with another value of the first byte is not greater than 1. For example, it is possible to obtain a Binary Sequence Length

Maximum (SBLM or MLBS for Maximum Length Binary Sequence English), by means of a generator polynomial with binary coefficients L. A SBLM consists of N bits. A vector consisting of N elements each associating the value -1 to a first bit value and the value 1 to a second bit value, has an interesting property. The scalar product of this vector with any vector consisting of the same by means of a circular permutation of the SBLM is equal to -1. then there exists N vector whose scalar product with another vector equals -1, which is below 1. It is thus possible to match N vectors at N different values ​​of the first byte of L bits. However this only allows matching a separate vector with N = 2 L -1 first bytes while there are 2 L possible values. The amount of areas that can be referenced by the binary word is then reduced accordingly.

According to a particularly advantageous mode of carrying out the invention, the method is characterized in that the component values of each 2-L "1 first vectors, resulting in a different circular shift on the same first bit sequence of maximum length N values and in that the component values of each 2-L "1 other vectors are of opposite sign to the one different component values of the 2 L" 1 first vectors.

The scalar product of two different first vectors is equal to -1. The scalar product of two different second vectors is equal to -1. The scalar product of a first vector with a second vector whose components are the result of sign reversal of those of the first, is equal to -N. The scalar product of a first vector with any other second vector is equal to one. It is thus possible to match 2 L vectors The first 2 bytes. Each of the possible values ​​of the binary word may then reference a sector. Different choices are possible for the values ​​of the numbers M, L, P. Considering a data carrier configuration with a groove 248 oscillations per sector, a particularly interesting choice is to retain the values ​​M = 12, L = 4 and P = 63. The values ​​of M and L are used to obtain a binary 48-bit word that can then reference, taking into account 16-bit correction for a Reed-Solomon code, up to 2 power 32 sectors. The value of L = 4, gives a value N of 15 bits for each second byte. It is then possible to burn the succession of M second bytes 180 of oscillation of the groove alternations. Of the 68 remaining alternations, 63 may be used to etch the sync byte.

The invention will be better understood from the description of an embodiment which follows with reference to drawings in which:

- Figure 1 shows a means for generating vectors in accordance with the invention;

- Figure 2 shows a correspondence table according to the invention;

- Figure 3 shows an information carrier to implement the invention;

- Figures 4 to 6 each show a local expansion of the groove to highlight possible amendment of alternation;

- Figures 7 and 8 show operating means of the invention.

Referring to Figure 1, a means for generating a binary sequence of maximum length (SBLM) is shown as a circuit diagram. It is possible to recreate this pattern as a program without any particular difficulty. This circuit or the program is implemented prior to the process of the invention.

A register 1 to L frozen outputs, consists of L bits 10, 11, 12, 13, each representing a coefficient of a generator polynomial of degree L-1. A shift register 2 consists of L bits 20, 21, 22, 23. The logic gates 30, 31, 32, 33 combine in pairs, respectively the bits 10 and 20, 11 and 21, 12 and 22, 13 and 23. the output of each gate 30, 31, 32, 33 is received by a separate input of a register of L bits 4 40, 41, 42, 43. a logic gate 5 combines the bits of the register 4. the door 5 is a XOR gate, that is to say that its output is at 1 if one and only one bit of the register 4 is 1. the output of the gate 5 is 0 in all other cases. On the other hand, the output of gate 5 is fed back to the input of shift register 2.

For example, a first phase of a two-phase clock, the register 4 performs a bitwise logical disjunction of the registers 1 and 2. In a second phase of the two-phase clock, the first bit 20 in the shift register input 2 receives the exclusive OR of bits of the register 4, driving the previous value of bit 20 to bit 21 and so on until the last bit 23 receives the previous value of the bit 22. as in the example of Figure 1, the number L is equal to four, the bits 10, 11, 12, 13 are each respectively equal to 1, 0, 0, 1. in accordance with the results from the Galois field theory, the output of gate 5 generates steady state, a binary sequence of maximum length, i.e. of period N = 2 L -1 = 15. the output of the gate 5 is also sent to the input of a shift register 6 to 60 bits N , 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74. the complement of the output of gate 5 is sent to the input of a shift register 8 to N bits 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94. It can be seen the values ​​1, 0, 0, 1 of the register 1, generate a bit sequence 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, each respectively 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 1, 1, 1 and simultaneously a sequence of bits 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, each respectively equal to 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 0, 0, 0. Each second stage of the two-phase clock causes a circular permutation of bit sequence of maximum length (SBLM) contained in registers 6 and 8.

Replacing the bit values ​​0 and 1 of a SBLM contained in the register 6 or register 8, respectively by binary values ​​-1 and +1, there is obtained a vector with N components that have advantageous properties. The scalar product of two vectors obtained from two different SBLM the same register 6 or 8 is equal to one. The scalar square of a vector is naturally equal to 15, the square of each element being equal to one. The dot product of a vector with the same opposite sign vector is equal to -15, that is the case for two vectors obtained from a SBLM register 6 and the complementary SBLM register 8. The scalar product two vectors obtained from a register 6 and SBLM another SBLM register 8 is equal to -1. The periodicity of SBLM makes it possible to obtain 2N, thirty different vectors.

A four-bit byte may take sixteen different values. Referring to Figure 2, it establishes a correspondence table 7 by means of which there corresponds a different vector for each possible value of said first byte of four bits. The lookup table comprises N + 1 lines, i.e. here sixteen lines with a first column containing for each line a value of 0000 byte from the first line to the value 1111 on the last line. A second column of each line a vector as described above.

The first eight-line, the second column contains a vector resulting from a register SBLM 6. The first line contains for example the vector (-1, 1, -1, 1, 1, -1, -1, 1, -1, -1, -1, 1, 1, 1, 1) resulting from the SBLM (0.1, 0.1, 1, 0,0,1, 0,0,0,1, 1, 1, 1). Each following line contains the previous line with a double circular permutation. The last eight lines show the first eight lines by reversing the sign of each component of the vector.

Figure 3 shows an information carrier on which is implemented the invention. Here, the recording medium is an optical disc 9. A write head 19 is provided for emitting a laser beam 26 whose power, controlled by a signal 29 allows to record on the disc a groove 17 whose depth is equal to a wavelength shift of the reflected laser beam 25, receivable by a reading head 18.

A micro motor 24 is provided for moving the entire read head 18, write head 19 in a radial direction of the disk 9. An integrated circuit controller 15 control of the whole reading head 18, write head 19 includes a servo block 27. the block 27 controls the motor 24 by means of a signal 28. the signal 28 from a first value which sets all reading head 18, write head 19 close from the center 14 of the disk until a last value which sets all reading head 18, write head 19 to the periphery of the disk 9.

As the disk 9 rotates about its center 14, the signal 28 is changing from the first to the last value to write to the disc 9 the groove, which in a first said macroscopic scale, has the shape of a spiral that from the center 14 to the periphery of the disk 9.

While the signal 28 is changing from the first to the last value, the latter is modulated by an oscillation of the first frequency and first amplitude determined, so that a second said microscopic scale, the groove 17 has a sinusoidal shape.

If during the etching of the groove 17, the disk 9 rotates at a constant angular velocity, the sinusoidal shape of the groove is of constant angular geometric period for the first predetermined frequency.

If during the etching of the groove 17, the disk 9 is rotated at a controlled angular velocity in the radial position of the whole reading head 18, write head 19, so as to maintain a constant linear velocity of movement of the disc 9 in the writing head 19, the sinusoidal shape of the groove is constant linear geometrical period for the first predetermined frequency.

Microscopic scale oscillation of the groove then allows tracking of subsequent rotations of the disk 9 in a homothetic speed than the etching for the same radial position of the whole reading head 18, write head 19.

The integrated circuit 15 includes the correspondence table 7 and a write logic block 34. The write logic block 34 is provided to generate a signal 35 which modulates the signal 28.

The device just described allows to perform actions of etching on the disk 9 a succession of bytes as explained now.

An integrated element external to circuit 15, for example a computer, generates a binary word 16, the reference value provided a sector on the disk

9. The binary word 16 consists of a number M of first bytes each comprising L bits. In the embodiment described herein, M is set equal to twelve and L is set equal to four. The write logic block 34 of the integrated circuit 15, receiving the value of the binary word 16, matches each first byte vector correspondence table 7, so as to constitute a second byte of N bits.

Zero for each bit in a byte, the logic block 34 generates a signal 35 which reproduces an unmodified alternation, that is to say at the first frequency and the first predetermined amplitude, so as to modulate the signal 28 . for each bit in one of a byte, the logic block 34 generates a signal 35 which reproduces an alternation modified relative to that at the first frequency and the first predetermined amplitude. Different possible alternation changes are described below.

Logic block 34 starts modulating the signal 28 for etching a groove in the third byte of said synchronization, consisting of a SBLM of P bits. In the embodiment described herein, P is set equal to sixty three. As a result, the logic unit 34 modulates the signal 28 to burn in the groove each of the second byte. Each bit of the sequence consisting of the third and second bytes M, is engraved on a vibration of the oscillation of the groove. In the example described here, this suite is well etched on two hundred forty three basic alternations. Then, the logic unit 34 modulates the signal 28 with five alternating unmodified. During etching on two hundred and forty eight half-waves of oscillation of the groove locally to an area, the logic block 34 receives a new binary word reference value 16 for the next sector. As above, the logic block 34 maps M new second byte to the first M bytes of the new value of the binary word 16. As before, logic block 34 the signal 28 module for etching a new sequence consisting of the byte synchronization tracking M new second bytes. This is repeated until the end of the groove 17 or the last value of the binary word 16.

In a binary word 16 of forty eight bits where a byte is reserved for information eg on the disc type and two bytes are dedicated to a type of correction Reed-Solomon on the binary word, there are three bytes to identify the sector . This allows referencing sixteen million sectors with high reliability. With two hundred and forty eight alternating oscillation in the first sector and frequency determined by a write possibility of fifty six data bits alternately beside the furrow, each sector may contain on the order of 4.7 mega bytes . Such a disc can hold about 75 gigabytes. Figures 4 to 6 show different possible changes alternately.

Figure 4 shows alternating modification superimposing a frequency of oscillation triple unmodified initial alternation frequency. Alternating 37 remains in the initial absence of spatial frequency by the modulation signal 29 when a bit byte is 0. alternating 38 is changed to a triple spatial frequency modulation by the signal 28 when a bit is 1 byte . by superimposing the three-frequency-oscillation on an entire alternation period to the original spatial frequency, the envelope of the oscillation at the initial frequency is stored. A speed of rotation of disc 9, the spatial oscillation of the groove 17 modulates the laser beam 25 on the whole of a period and thus saves energy detection. A multiplication by three of the spatial frequency for an initial period, multiplies all the temporal frequency. It is then necessary to provide a filter in the portions of the integrated circuit 15 which deal with the clock signals to reduce the bandwidth around the initial frequency. When the parts of the integrated circuit 15 which process the clock signals essentially detect from values ​​on either side of zero on an alternation, it is observed in Figure 4 that the zero crossing of a modified alternation being retained, detecting the clock frequency is undisturbed. 5 shows an alternation of modification by increase in amplitude. Alternating 37 remains at the initial spatial amplitude with no modulation of the signal 29 when a bit byte is 0. alternating 38 is changed to a triple amplitude modulation of the signal 29 when a bit is 1 byte . This alternation of modification has the advantage of keeping the spatial frequency.

6 shows an alternation of modification superimposing one alternating oscillation to a fivefold frequency of an unmodified initial alternation frequency. Alternating 37 remains at the initial spatial frequency by no modulation of the 29 byte when a bit signal is 0. alternating 44 is modified by superposing at its center with an alternation at a spatial frequency five times larger, by modulation of 29 when a bit byte signal is 1. by superimposing one oscillation alternately at a much higher frequency, the form of the alternation is identical to the initial shape on two-fifths the beginning of the period and two-fifths end of the period of the initial shape. This reduces the disturbances on the parts of the integrated circuit 34 responsible for monitoring the initial oscillation of the groove 17. This modification of this alternation the advantage of preserving the spatial amplitude but significantly reduces the change detection window.

These three modulations are remarkable for the ability to detect by matched filtering. Moreover, in each case, modulation is orthogonal to the sinusoidal modulation, which facilitates detection. The optical disc thus with pre-marked to reference its data recording areas can serve as a template for manufacture in large numbers of recordable information medium.

Such an information carrier comprises for each of its sectors referenced by a binary word consisting of first M bytes each comprising L bits, a succession of M second bytes each comprising N bits whose values ​​are interpreted as values ​​+ or -1 N components of an associated vector as the scalar product of said vector with any vector associated with other values of the second byte and at most equal to 1, with N = 2 L -1. These M second bytes, preceded by a sync byte for each sector are preferably etched on the groove by changing alternating micro spatial oscillations of the groove. As explained in the following description, these pre-brands enable a system for recording and playback or to recognize the information carrier sector to record or to read computer data.

7 shows operating means for such a record carrier. These operating means comprise a similar or different arrangement of the device of FIG 3. With reference to Figure 7, an optical disc 45 includes a spiral groove 47 extending from the center 46 to the periphery and whose depth is equal to a quarter of a laser beam of wavelength 49 receivable by a read head 48. When the disk 45 rotates about its center 46, the laser beam 49 received by the head 48 allows tracking position thereof to follow the median line of the groove. A write head 50 mechanically linked to the read head 48 is provided to record signals on the disc 45, next to the groove 47 by means of a laser beam 51.

A micro motor 52 is provided for moving the entire read head 48, write head 50 in a radial direction of the disk 45. An integrated circuit 53 of control control of the whole reading head 48, write head 50 includes a servo block 54. the block 54 controls the motor 52 to keep constant a signal value 55 modulated by the received power of the laser beam 49. At a microscopic scale, the groove 17 has the shape of a sinusoidal oscillation at least a first harmonic has a constant geometric period. The entire read head 48, write head 50 is equipped with a pair of photodetectors 60, 61 arranged perpendicular to the groove. The image of a task 62 (spot English) of light reflected by the groove 47 of the two detectors 60, 61 generates a 63-type push-pull signal (push-pull in English) as the difference of light intensities received by each of the photodetectors 60, 61. the signal 63 contains the first harmonic which, detected by the integrated circuit 53, to measure the linear speed of movement of the disc under the set reading head 48, write head 50. of these oscillations, certain alternations are identical to the first harmonic with a base amplitude, others include a second harmonic or are of different amplitude, are modified alternations described above. Each alternately altered causes an additional signal modulation type push-pull during its passage under the pair of photo-detectors 60, 61.

The integrated circuit 53 includes the correspondence table 7 and a logic block 57. The read write write logic block reading 57 is provided to generate a signal 58 of power modulation of the laser beam 51 emitted by the writing head 50.

The device just described allows to perform actions comprising positioning the read head 48, write head 50 on a given sector of the disk 45.

An element external to integrated circuit 57, for example a computer, generates a binary word 56 which reference value the specified sector on the disk 45. The binary word 56 consists of a first series of M bytes each comprising L bits. In the embodiment described herein, M is set equal to twelve and L is set equal to four.

On the other hand, logic block 57 receives the signal 63. The logic block 57 interprets the signal as being worth 1 63 when the signal 63 due to an additional modulation of the reflected laser beam 49 caused by a deformed alternately. The logic block 57 interprets the signal as being worth 63 -1 otherwise. Thus, the logic block 57 receives the signal 63, a succession of binary values ​​equal to + or -1.

When the logic unit 57 receives a succession of binary values ​​that correspond to the bits of the synchronization byte, the logic block 57 is the dot product of N binary values ​​immediately following the last bit of the sync byte, with each vector table correspondence. The sync byte allows the logic block 57 to accurately detect the first bit of the first byte of the second series engraved on the disc.

Logic block 57 retains the vector of the correspondence table whose scalar product with the binary values ​​received from the signal 55, has the largest value. This vector is one that has the highest probability match the second byte engraved on the groove at the location which passes under the read head 48. In the absence of error, this scalar product is equal to N. The logic block 57 then emits outwardly, the first byte which corresponds in the table 7 in the second byte.

In no error, we have seen that the dot product of two vectors is equal to N, for example fifteen. The scalar product of two different vectors is less than or equal to 1, for example -15, -1 or +1. A read error on a bit reduces the scalar product of two vectors equal to N-2, for example three. A read error on a bit increases the scalar product of two different vectors of two units in the worst case. So that the scalar product of two equal vectors is not greater than (N + 1) / 2, for example eight, it takes at least (N + 1) / 4 errors that do not compensate for, for example four errors N = 15. So that the scalar product of two different vectors is greater than (N + 1) / 2, for example eight, it takes at least (N + 1) / 4 errors that do not compensate for, for example four errors for N = 15. If the logic block 57 detects the signal 63, a set of second bytes all of which correspond each to a first byte of the same rank from the binary word 56, logic block 57 transmits the signal 59 to the servo block 54, an order for holding in position of the read head 48 on the detected sector as the one referenced by the binary word 56.

The integrated circuit 53 and read access or write to a register 36 for containing computer data to be recorded or recorded on the disc 45.

For controlling a writing of computer data on a given sector of the disk 45, the outer member to the integrated circuit 57, for example a computer, generates a binary word 56 with a value reference the specific sector. The outer member, not shown, stored in the register 36, the computer data to write the sector.

When the logic unit 57 has positioned the write head 50 connected to the read head 48, on the title area of ​​the disc 45, the logic block 57 loads the data contained in the register 36 for modulating the signal 58 to the write head 50, so register registry data 36 of the referenced sector of the optical disk 45.

For controlling a computer data read on a given sector of the disk 45, the outer member to the integrated circuit 57, for example a computer, generates a binary word 56 with a value reference the specific sector. When the logic unit 57 has positioned the read head 48 on the referenced sector of the disk 45, the logic block 57 converts the modulation signal 55 representative of data recorded on the sector referenced in computer data bytes that stored in the register 36. the outer member not shown, then read in the register 36, the data recorded on the title area of ​​the optical disk 45.

The integrated circuit 53 which has just been described, has good qualities of reliability to recognize a sector referenced on the optical disc 45.

The teaching of the invention is not limited to the example just described. In particular, the skilled person based on the results from the Galois theory can imagine other vector systems satisfying the above properties contained within the scope of the present invention, for example with other values ​​of M and L or alternation with other modifications of oscillations of the guide groove on the information carrier.

The skilled artisan will appreciate that, by matching a different vector for each possible value of a first byte of L bits, the properties of the scalar product are advantageously used for detecting a vector that has the highest probability correspond to a value of first byte.

Claims

1. A method of indicating on an information medium, an area referenced by a binary word consisting of a number M of first bytes each comprising a number L of bits, characterized in that it comprises the actions of etching on the information carrier locally to the sector, a series of M second bytes each corresponding to a first byte, second byte each being equal to a vector of N components, each of value +1 or -1, such that N = 2 L - 1 and such that the inner product of said vector with any vector which is equal to another second byte, is at most equal to 1.
2. Method according to claim 1, characterized in that one of the values ​​+1 or -1 is etched by changing an amplitude of a wobble period of a groove on the information carrier.
3. The method of claim 1 or 2, characterized in that one of the values ​​+1 or -1 is etched by multiplying an initial three wobble frequency on the screen of an initial period of alternans.
4. Method according to one of the preceding claims, characterized in that a third said synchronization byte is added to the head of the sequence of M second bytes, said sync byte being composed of a binary sequence of maximum length of P bits with P greater than Ν.
5. A method as claimed in one of the preceding claims, characterized in that the component values of each 2-L "1 first vectors, resulting in a different circular shift on the same first bit sequence of maximum length of Ν values and in that components of the two values of each of L "1 other vectors are of opposite sign to the one different component values of the 2 L" 1 first vectors.
6. A method according to claim 4, characterized in that M = 12, L = 4 and P = 63.
7. A method according to claim 6, characterized in that the component values ​​of each of the first eight vectors, resulting in a different circular shift on the same first bit sequence with a maximum length of fifteen values ​​and in that the component values each of eight vectors are of opposite sign to the one different component values ​​of the first eight vectors.
8. Information carrier (45) comprising a plurality of sectors for recording computer data, characterized in that it comprises locally in each segment referenced by a binary word consisting of a number M of first bytes each comprising a number L of bits a succession of M second bytes each corresponding to a first byte, second byte each being equal to a vector of N components, each of value +1 or -1, such that N = 2 L - 1 and such that the scalar product of said vector by any other vector which is equal to another second byte, is at most equal to 1.
9. Information Medium according to Claim 8, characterized in that one of the values ​​+1 or -1 is etched in the form of a modified amplitude of ripple period of a groove (47) on the carrier 'information.
10. Information Medium according to claim 8 or 9, characterized in that one of the values ​​+1 or -1 is etched in the form of three frequency alternating three times larger than an initial frequency ripple of a groove (47) on the information carrier, added over a period of undulation of said groove.
11. Information carrier according to one of the preceding claims, characterized in that a third said byte synchronization is ahead of the succession of M second bytes, said sync byte being composed of a binary sequence maximum length of P bits with P greater than N.
12. Information carrier as claimed in one of the preceding claims, characterized in that the component values of each 2-L "1 first vectors, resulting in a different circular shift on the same first bit sequence of maximum length N values and in that the component values of each 2-L "1 other vectors are of opposite sign to the one different component values of the 2 L" 1 first vectors.
13. Information carrier according to claim 11, characterized in that M = 12, L = 4 and P = 63.
14. Information Medium according to claim 13, characterized in that the component values ​​of each of the first eight vectors, resulting in a different circular shift on the same first bit sequence with a maximum length of fifteen values ​​and in that the component values ​​of each of eight vectors are of opposite sign to the one different component values ​​of the first eight vectors.
15. An integrated circuit (53) for detecting on an information carrier (45), a recording area referenced by a binary word (56), characterized in that it comprises:
- a correspondence table (7) which correspond to a succession of M bytes constituting the first binary word (56) with each a number
L bits, a succession of M second bytes each corresponding to a first byte, second byte each being equal to a vector of N components, each of value +1 or -1, such that N = 2 L - 1 and such that the scalar product of said vector with any vector which is equal to another second byte, is at most equal to 1;
- a logic block (57) arranged to the scalar product of a first vector of the correspondence table with a second vector derived from a signal (58) received into the integrated circuit (53) and arranged for detecting that the second vector corresponds to a first byte when the scalar product of the first and second vector is significantly greater than one.
16. Integrated circuit according to Claim 15, characterized in that the logic block (57) is arranged to detect a synchronization byte from the signal (58).
PCT/FR2002/001836 2001-06-07 2002-05-31 Method for indicating a sector on a data medium and data medium adapted to said method WO2002099802A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
FR01/07446 2001-06-07
FR0107446A FR2825827A1 (en) 2001-06-07 2001-06-07 Definition of sectors on optical disc includes engraving at local positions multiplets with specific vector values as reference points

Applications Claiming Priority (2)

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EP20020738291 EP1399923A1 (en) 2001-06-07 2002-05-31 Method for indicating a sector on a data medium and data medium adapted to said method
US10729192 US7239592B2 (en) 2000-04-03 2003-12-05 Method for indicating a sector on a data medium and data medium suited to this method

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Citations (6)

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US5384671A (en) * 1993-12-23 1995-01-24 Quantum Corporation PRML sampled data channel synchronous servo detector
WO1997012363A2 (en) * 1995-09-26 1997-04-03 Cirrus Logic, Inc. Improved fault tolerant sync mark detector for sampled amplitude magnetic recording
US5715232A (en) * 1992-06-23 1998-02-03 Deutsche Thomson Brandt Gmbh Recording and reproduction of items of information using ROM-RAM storage media
US5867475A (en) * 1995-04-10 1999-02-02 Matsushita Electric Industrial Co., Ltd. Optical record carrier and method for recording and reproducing signals therefrom
US6208477B1 (en) * 1997-06-06 2001-03-27 Western Digital Corporation Hard disk drive having a built-in self-test for measuring non-linear signal distortion
WO2001075872A2 (en) * 2000-04-03 2001-10-11 Dataplay, Inc. Structure and method for storing data on optical disks

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5715232A (en) * 1992-06-23 1998-02-03 Deutsche Thomson Brandt Gmbh Recording and reproduction of items of information using ROM-RAM storage media
US5384671A (en) * 1993-12-23 1995-01-24 Quantum Corporation PRML sampled data channel synchronous servo detector
US5867475A (en) * 1995-04-10 1999-02-02 Matsushita Electric Industrial Co., Ltd. Optical record carrier and method for recording and reproducing signals therefrom
WO1997012363A2 (en) * 1995-09-26 1997-04-03 Cirrus Logic, Inc. Improved fault tolerant sync mark detector for sampled amplitude magnetic recording
US6208477B1 (en) * 1997-06-06 2001-03-27 Western Digital Corporation Hard disk drive having a built-in self-test for measuring non-linear signal distortion
WO2001075872A2 (en) * 2000-04-03 2001-10-11 Dataplay, Inc. Structure and method for storing data on optical disks

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EP1399923A1 (en) 2004-03-24 application

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