WO2007122575A2

WO2007122575A2 - Method and device for mounting a rewritable optical disc

Info

Publication number: WO2007122575A2
Application number: PCT/IB2007/051460
Authority: WO
Inventors: Jurgen M. Vangeel; Dominique M. G. J. Spelmans
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2006-04-25
Filing date: 2007-04-20
Publication date: 2007-11-01
Also published as: WO2007122575A3; JP2009535754A; CN101432814A; EP2013878A2; KR20080113294A; TW200813999A; RU2008146401A

Abstract

A method of handling an optical disc of the rewritable type, the method comprising a disc recognition step comprising determining information with respect to the type of optical disc, a mounting step comprising reading information with respect to logical disc structures, and a formatting step succeeding the mounting step, comprising formatting the optical disc if the disc recognition step was successful but information with respect to the logical disc structures could not be read. The method allows in a PC reformatting of optical disc when basic disc information is available.

Description

Method and device for handling optical discs of the rewritable type

FIELD OF THE INVENTION

The present invention relates to a method of handling an optical disc of the rewritable type comprising identification of the type of optical disc and mounting of logical structures. This invention also relates to device for recording an optical disc of the rewritable type and a computer software product.

BACKGROUND OF THE INVENTION

When an optical disc is inserted into a drive unit, several actions need to be performed successfully so that information may be read from or recorded onto the disc. Firstly, the exact type of optical disc needs to be recognized, so that the readout apparatus can adapt the reading and/or recording method to the type of optical disc. Secondly, the disc needs to be mounted, this step comprising reading logical file structures. If both steps are successful, the disc is made available to be used by the end user. If errors are detected either in the disc recognition step or during mounting, a known drive reports the disc as damaged and the end-user cannot use it.

However, this is not attractive to the end-user, which may be not have other disc available and may be interested in being able to still use the disc.

SUMMARY OF THE INVENTION It is an object of the invention to provide a solution to the above problem of allowing the user to use certain types of discs that were reported as damaged. The object of the invention is reached by a method of handling an optical disc of the rewritable type according to the invention. In the method according to the invention, a formatting step succeeding the mounting step, comprising formatting the optical disc if the type of optical disc was identified in the disc recognition step, but the information with respect to the logical disc structures comprises errors or could not be read. This is based on the insight that discs that do not mount because certain logical disc structures cannot be read, they should be nevertheless formatable. Formatting allows re-use of the optical disc at the price of losing all saved information, and it order to be possible, it only requires the availability of information obtained during disc recognition and no information with respect to the logical disc structures already present on disc is needed. While discrimination between different types of optical disc, such as between CDs and DVDs is usually done by means of optical beam parameters, further discrimination, such as between DVD+RW, DVD-RW and DVD-RAM, may be obtained either from information recorded in the lead in area or from information prerecorded in the wobble during manufacturing. It is advantageous to retrieve information prerecorded in the wobble, as this does not require the ability to recorded data.

In an advantageous embodiment, the method further comprising a recovery step preceding the formatting step, if the information with respect to the logical disc structures comprises errors, the recovery step comprising recovering at least part of the user data stored on the optical disc before the formatting step. The errors encountered during the mounting step may be related either to errors in retrieving disc management information or errors in retrieving file system information. In the latter case, it may be possible that the file system can be partially mounted. In such cases, it is advantageous to recover the information stored in files that were properly mounted.

In an advantageous embodiment of the method, the defect management is enabled during the formatting step. In general, the use of defect management is optional. However, in view of the fact that it is more likely than usual that the disc has unusable areas as a previous attempt to mount the disc failed, use of defect management would reduce the risk of errors when storing data. Moreover, advantageously, the formatting step may further comprise a verification step, comprising checking for unreliable areas on the optical disc. The verification would ensure that unusable areas are identified before the disc being used.

The invention also includes a device for recording optical discs of the rewritable type according to claim 6. The invention also includes a computer software product which, when executed on a general-purpose processor, induced a recording device to execute the method of claims 1-5.

These and other aspects of the invention are apparent from and will be explained with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the invention will be further explained upon reference to the following drawings, in which: Fig. 1 illustrates schematically an optical disc;

Fig. 2 shows schematically an optical drive wherein the invention is practiced; Fig. 3 illustrates by means of a flow diagram a method of handling an optical disc according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. Ia illustrates schematically an optical disc 11 having a track 12 and a central hole 10. The track 12, being the position of the series of (to be) recorded marks representing information, is arranged in accordance with a single spiral pattern constituting substantially parallel tracks on an information layer. The optical disc may comprise one or more information layers of a recordable type. Known examples of rewritable optical discs are CD-RW, or DVD+/-RW, DVD-RAM or BD-RE. For example, further details about the physical structure and addressing information for DVD+/-RW optical discs can be found in references ECMA-337 and ECMA-338, respectively. The information is represented on the information layer by recording optically detectable marks along the track, for instance crystalline or amorphous marks in phase change material. The track 12 on the optical disc is indicated by a pre-embossed track structure provided during manufacture of the blank optical disc. The track structure is constituted, for example, by a pregroove, which enables a read/write head to follow the track during scanning. The track structure of recordable disc comprises variation of a physical parameter, known in the art as a wobble, usually in the form of periodical radial displacements of the groove from an average centerline. The periodic wobble is further modulated so that further information is stored, such as physical addresses indicating the location of units of information. Said information may further include specific synchronizing marks for locating the start of such information blocks. The position information is encoded in groups comprising a predetermined number of modulated wobbles. However, the information encoded in the wobble is not limited to address information. For example, in the case of a CD-RW disc, in the wobble the following information is stored: time information (physical address); write powers at different speeds; start time of lead-in, lead-out and velocity range. For DVD+RW discs, the stored information may comprise: physical address, Disc Category (e.g. DVD+R, DVD+RW), Disc Size and maximum transfer rate, Disc Structure (e.g. recordable layers, rewritable layers), Recording Density, Data Zone allocation (start and stop address of the data zone), Disc Application code, Disc ID, Manufacturer ID or Write strategy parameters (velocity range, read/write powers for several speeds). In case of BD RE disc, a prerecorded area known as PIC area is present, wherein the following information may be stored: media type; write strategies and alternative strategy for different speeds, velocity range, read powers for different speeds, disc size, number of layers, data zone allocation (start and stop address of the data zone). The information is repeated 5 times for robustness. The above information stored in the wobble is information on how to handle an optical disc and it does not give information on the actual recording that is on the disc. The optical disc 11 is intended for carrying user information according to a standardized format, to be playable on standardized playback devices. The recording format includes the way information is recorded, encoded and logically mapped onto the recording space provided by the track 12 and it will be described with reference to Fig Ib. The recordable space is usually subdivided into a lead-in area (LI), a data zone (DZ) for recording user data and a lead-out area (LO). The lead-in area (LI) usually comprises an area 13 wherein basic disc management information is stored and a disc description area 14 wherein information how to physically access the data zone is provided. For example, said basic disc management information corresponds to the table of contents in CD systems or the formatting disc control blocks in DVD systems. Further, at logical level, the user data in the data zone is arranged according to a file system comprising file management information, such as ISO 9660 used in CD systems, available as ECMA-119, or UDF used in DVD systems, available as ECMA- 167. Such file management information is mapped on a predefined location 15 on the optical disc 11, usually in or directly after the lead-in area (LI). The user information recorded in the data zone (DZ) may be further arranged according to an application format, for example comprising a predefined structure of files and directories.

Fig. 2 illustrates schematically a recording device for writing information on the optical disc 11 as illustrated with reference to Fig. Ia. The recording device is provided with recording means for scanning the track on the optical disc, the recording means comprising a drive unit 16 for rotating the optical disc 11, a head 18, a positioning unit 21 for coarsely positioning the head 18 in the radial direction on the track, and a control unit 17. The head 18 comprises an optical system of a known type for generating a radiation beam 20 guided through optical elements for focusing said radiation beam 20 to a radiation spot 19 on the track 12 of the optical disc 11. The radiation beam 20 is generated by a radiation source, e.g. a laser diode. The head further comprises (not shown) a focusing actuator for moving the focus of the radiation beam 20 along the optical axis of said beam and a tracking actuator for fine positioning of the radiation spot 19 in a radial direction on the center of the track. The tracking actuator may comprise coils for radially moving an optical element or may alternatively be arranged for changing the angle of a reflecting element.

For reading information, the radiation reflected by the information layer is detected by a detector of a usual type, e.g. a four-quadrant diode, in the head 18 for generating a read signal and further detector signals, such as a tracking error and a focusing error signal for controlling said tracking and focusing actuators.

For recording information the radiation beam 20 is controlled to create optically detectable marks in the recording layer. For this purpose, the recording device comprises write processing means for processing input information to generate a write signal to drive the head 18, which write processing means comprise an input unit 23; and data processing means comprising a formatter 24 and a modulator 25.

The control unit 17 controls the recording and retrieving of information onto and from the optical disc 11 , and may be arranged for receiving commands from a user or from a host computer. To this end, the control unit 17 may comprise control circuitry, for example a microprocessor, a program memory and control gates, for performing the procedures described hereinafter with reference to Fig. 3. The control unit 17 may also be implemented as a state machine in logic circuits. The control unit 17 is connected via control lines 22, e.g. a system bus, to said input unit 23, formatter 24 and modulator 25, to the drive unit 16, and to the positioning unit 21. The input unit 23 receives and pre-processes the user information. For example, when processing audio-video information, the input unit 23, may comprise compression means for compressing input signals such as analog audio and/or video, or digital uncompressed audio/video. Suitable compression means are described for audio in WO 98/16014-A1 (PHN 16452), and for video in the MPEG2 standard (ISO-IEC 13818). The input signal may alternatively be already encoded. The output of the input unit 23 is passed to the formatter 24 for adding control data and formatting the data according to a recording format, e.g. by adding error correction codes (ECC) and/or interleaving. For computer applications units of information may be interfaced to the formatter 24 directly. The formatted data from the output of the formatter 24 is passed to the modulation unit 25, which comprises for example a channel coder, for generating a modulated signal, which drives the head 22. Further the modulation unit 25 comprises synchronizing means for including synchronizing patterns in the modulated signal. The formatted units presented to the input of the modulation unit 25 comprise address information and are written to corresponding addressable locations on the optical disc under the control of control unit 17. The control unit 17 is arranged for recording and retrieving position data indicative of the position of the recorded information volumes.

During the recording operation, marks representing the information are formed on the optical disc. The marks may be in any optically readable form, e.g. in the form of areas with a reflection coefficient different from their surroundings, obtained when recording in materials such as dye, alloy or phase change material, or in the form of areas with a direction of magnetization different from their surroundings, obtained when recording in magneto- optical material. Writing and reading of information for recording on optical disks and usable formatting, error correcting and channel coding rules are well-known in the art, e.g. from the CD system (IEC 908).

For reading, the read signal is processed by a read processing unit comprising a demodulator 26, a de-formatter 27 and output unit 28 for outputting the information. The functioning of the demodulator 26, the de-formatter 27 and the output unit 28 are controlled by the controller 17. Hence, retrieving means for reading information include the drive unit 16, the head 18, the positioning unit 21 and the read processing unit.

Fig. 3 illustrates by means of a flow diagram a method of handling an optical disc according to the invention.

When an optical disc is inserted in a device, first a disc recognition step 40 is performed (DSC REC). This step is known in the art, and may involve in a first sub-step first determination of parameters of reflected radiation (e.g. focusing) to determine whether the optical disc is of the CD, DVD or BD type. After the type of disc has been identified, further basic disc information is retrieved, so that basic read/write parameters and the location of the lead-in area, data zone and lead-out are determined. It is noted that basic disc information can be either retrieved from the information encoded in the wobble or from the information recorded in the lead-in area.

In step 41, it is checked whether disc recognition was successful. If disc recognition failed, without any basic information about the disc being available, the disc is rejected as damaged in step 42.

If disc recognition was successful, it is followed by a mounting step 43 (MOUNT), wherein in a first sub-step disc management information recorded in the lead-in area is read. This information normally comprises information that allows accessing the logical layer. For example, in CD-RW systems this correspond to reading a table of contents (TOC), in DVD-RW systems it corresponds to reading the formatting disc control blocks (FDCB), and in BD-RE systems it corresponds to reading the (temporary) defect management area (T)DMA. Information present therein will indicate the format of the user data on disc, such as UDF or ISO 9660 and where the file information table is located. In a next sub-step, the file information table is accessed and the disc mounting is finished.

In step 44, it is checked whether disc mounting was successful. If disc mounting was successful, then the end user can use the disc in step 45, for example by reading and/recording data.

Disc mounting may be unsuccessful full due to the following types of errors: errors are encountered in reading basic disc management information, so that no information has been obtained in the mounting step either with respect to the type of format the user data has on the disc, or with respect to where file allocation information is recorded on disc; errors encountered in reading file allocation information.

When errors are encountered, in known optical drives the disc is rejected as damaged. However, in the method and device according to the invention if disc recognition was successful but disc mounting failed, instead of rejecting the disc as damaged, it is allowed that discs of the rewritable type are re-formatted in a formatting step 46 (FORMAT). This is based on the insight that only basic disc identification information, which can be extracted from the wobble, is necessary to format a disc. It is noted that when the latter types of errors is encountered, a recovery step (RECOV) may precede the formatting, as it will be detailed later.

The process of formatting an optical disc is known, and several options are usually available. The process known in the art as regular formatting is the conventional way of physical formatting used for optical disc such as CD or DVD. After the regular formatting process, the disc is fully formatted at physical level. The formatting process comprises recording the Lead-in area (LI), writing the Data Zone (DZ), writing the Lead-out area (LO), and optionally verification of the Data Zone and initialization of the Defect Management, if defect management is to be used. It should be noted that defect management may be handled outside the device, such as by the operating system of a computer. A second type of formatting process is known in the art as background formatting, which is a formatting process that runs in the background during use of the disc in a recorder. After the

Background Formatting process has been completed, the disc is fully physical formatted at physical level. User data may be recorded to the disc during the Background Formatting process. The Background Formatting process may comprise the following steps: initialization of the Defect Management; de-icing of the Data Zone, which may be optional, depending on the type of optical discs; finalization of the Lead-in and Lead-out Zones; early-eject finishing (if applicable); - restarting the Background Formatting on an early-ejected disc; verification (optionally selected by host computer).

In general Background Formatting is seen as a much more time-efficient solution for the user as during the initialization phase of the Background Formatting process only a minimum amount of data will be recorded onto the disc, after which the disc can be used by the application/user. A disc, on which a Background Formatting process is active, may be formatted further by the device in the background during the moments that the application is not accessing the disc.

In view of the fact that is expected that the disc most probably has unusable areas as a previous attempt to mount the disc failed, in a preferred embodiment of the invention regular formatting is used instead of background formatting. This allows that a full verification step 48 (VERIF) is performed before the disc is used. Verification is the process of reading and checking of all information blocks in the data zone of the disc. If an information block is found unreliable, defect management should be employed to avoid using such an information block for recording user information. With respect to defect management, different possibilities may be available, for example a regular disc format corresponding to a normal user data size and a normal defect replacement area, a heavy use disc format corresponding to a smaller user data size and a larger defect replacement area and a light use disc format corresponding to a maximal user data size and a minimal defect replacement area. In a preferred embodiment of the invention, the heavy use disc format is used, in view of the fact that the disc most probably has unusable areas as a previous attempt to mount the disc failed.

If reading disc management information, i.e. the type and location of file management system, in an embodiment of the method, the formatting step may be preceded by a recovery step 47 (RECOV). This may happen when errors are encountered during reading of file system information, so that the file system can only be partially mounted. This can be implemented by means of mounting the disc as a read only discs. In such cases, the information located in files that were properly mounted may be recovered. Moreover, if the drive can determine the logical disc layout of the disc but when the replacement areas used by defect management system are completely full, in a method according to the invention, in the recovery step 47, the disc will be mounted as a read-only disc. After mounting, the user can chose to reformat the disc, or decide to run a verification step, including the bad areas. This is based on the insight that some bad areas were due to dirt and grease present on areas of the disc and it is possible that the disc has been cleaned, implying that some areas that have been marked as defect become usable. If successful, new replacement area may be made available, so that the disc can be remounted as a rewritable disc.

With respect to implementing the invention in a device, it is note that disc recognition, disc mounting, formatting, reading and recording information on optical disc of the rewritable type as such are known. In a preferred embodiment the control unit 17 is enabled to handle an optical disc of the rewritable type according to the novel method described above, for example by means of suitable firmware. In an alternative embodiment, a decision unit 29 connected to the retrieving and recording means via the control lines 22 and further either connected to or incorporated in the control unit 17 is present. The decision unit 29 is for deciding, based on the output of the disc recognition and disc mounting steps, the steps to be performed, such as formatting and/or verification and/or recovery. Optionally, if the device is an optical disc drive in a personal computer, the invention may be implemented in software, enabling handling the drive according to the invention. Such software, may comprise the option that, if disc recognition is successful and disc mounting not, the user is asked whether interested in reformatting the disc or inserting a new disc. It should be noted that the above-mentioned embodiments are meant to illustrate rather than limit the invention. And that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verbs "comprise" and "include" and their conjugations do not exclude the presence of elements or steps other than those stated in a claim. The article "a" or an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements and by means of a suitable programmed computer. A computer program may be stored/distributed on a suitable medium, such as optical storage or supplied together with hardware parts, but may also be distributed in other forms, such as being distributed via the Internet or wired or wireless telecommunication systems. In a system/device/apparatus claim enumerating several means, several of these means may be embodied by one and the same item of hardware or software. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

Claims

CLAIMS:

1. A method of handling an optical disc of the rewritable type, the method comprising: a disc recognition step comprising determining information with respect to the type of optical disc; - a mounting step comprising reading information with respect to logical disc structures, characterized by the method further comprises: a formatting step succeeding the mounting step, comprising formatting the optical disc if the type of optical disc was determined in the disc recognition step, but the information with respect to the logical disc structures comprises errors or said information could not be read.

2. A method according to claim 1, characterized by the method further comprising a recovery step preceding the formatting step, if the information with respect to the logical disc structures comprises errors, the recovery step comprising recovering at least part of the user data stored on the optical disc before the formatting step.

3. A method according to claim 1, characterized by the defect management being enabled during the formatting step.

4. A method according to claim 3, characterized by the formatting step further comprising a verification step, comprising checking for unreliable areas on the optical disc.

5. A method according to claim 1, characterized by the disc recognition step comprises reading pre-recorded information stored in a wobble of a track of the optical disc.

6. A device for recording an optical disc of the rewritable type comprising: retrieving means for reading information from the optical disc; recording means for recording information onto the optical disc; control means for controlling the reading and recording means to execute the method of any of the claims 1-5.

7. A computer software product which, when executed on a general-purpose processor, induced a recording device to execute the method of claims 1-5.

8. A recording medium comprising a computer software product according to claim 7.