WO2008029364A1

WO2008029364A1 - Recordable optical disc, method and recording device for recording css protected content on the recordable optical disc

Info

Publication number: WO2008029364A1
Application number: PCT/IB2007/053582
Authority: WO
Inventors: Robert A. Brondijk; Tony P. Van Endert; Johannes L. Bakx; Petrus H. C. Bentvelsen
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2006-09-07
Filing date: 2007-09-05
Publication date: 2008-03-13
Also published as: TW200832384A

Abstract

Copyrighted material is currently only distributed on read-only media and is additionally protected using the Content Scrambling System, also known as CSS. To allow a more flexible distribution of the copyrighted material it is the desire of the copyright owner to be able to record the copyrighted material locally in a store on a recordable optical disc instead of distribution via read-only optical discs a recordable record carrier is provided where the wobble is absent in the disc recognition zone. A recorder able to record in the absence of a wobble can record the CSS material on such a disc, yet the playback device is not able to detect the recordable nature of the optical disc and will determine the disk type as read-only, thus avoiding a rejection of the optical disc due to a detected combination of a recordable record carrier and CSS protected material on the optical disc.

Description

Recordable optical disc, method and recording device for recording CSS Protected content on the recordable optical disc

FIELD OF THE INVENTION

This invention relates to an recordable optical disc comprising a groove for storing data, the groove comprising a wobble and a disc recognition zone.

BACKGROUND OF THE INVENTION

Such a disc is currently on the market in the form of CD-R, DVD+R,

DVD+RW, DVD-R, DVD-RW, HD-DVD-R, HD-DVD-RW, BD-R and BD-RE discs. These discs comprise a groove for guiding the optical beam during recording of the data on the recordable medium. To allow assist the recording device during the recording of the data a wobble was added to the groove. The wobble itself provides a reference for the pit length while the modulation of the wobble provides addressing information, allowing the recording device to determine where it is currently recording data on the disc.

The wobble is further used by playback and recording device manufacturers to detect that the disc is of the recordable type. Read-only versions of these media do not have a wobble.

Copyrighted material is currently only distributed on read-only media and is additionally protected using the Content Scrambling System, also known as CSS.

CSS has been hacked several years ago and the skilled person can remove CSS from any optical disc when making a backup copy. To allow a more flexible distribution of the copyrighted material it is the desire of the copyright owner to be able to record the copyrighted material locally in a store instead of distribution via read-only optical discs. This is however not possible because an optical disc of the recordable type on which material is stored protected by CSS will be rejected by the playback device and recording device. Hence a requirement instated by the copyright owners now prevents the same copyright owners from distributing their copyrighted material on a recordable medium.

It is consequently a disadvantage of the current recordable optical disc that it can not be used for the distribution of copy righted material protected by CSS. SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a recordable optical disc that can be used for the distribution of copy righted material protected by CSS.

In order to achieve this objective the optical disc according to the invention is characterized in that all wobble is located outside the disc recognition zone.

Since the recognition of the disc type is performed in the disc recognition zone an absence of wobble in the disc recognition zone will ensure that the playback device will not recognize the optical disc as being recordable. Consequently the playback device will have no objection to reproducing the CSS protected content of the disc, even though it is actually recorded on a recordable medium

In an embodiment of the recordable optical disc the disc recognition zone is located between 23.4 and 28.0 mm from a center of the optical disc.

This implies that the wobble must be located outside the 23.4 to 28.0 mm zone measured from the center of the disc. Since all recorders use this zone between 23.4 and 28.0 mm to determine the type of the optical disc (Read-only / recordable / rewritable , single layer / dual layer) the absence of any wobble from this zone will cause the playback device to determine the type of the recordable optical disk as non-recordable. The algorithm inside the playback device will thus allow the playback of CSS protected copyrighted content because it is misled by the absence of the wobble in the disk recognition zone. In a further embodiment of the recordable optical disc all wobble is located between 21.0 and 23.4 mm from the center of the optical disc.

Between 21.0 and 23.4 mm the groove is present and can safely comprise a wobble since no playback device will search in this area for a wobble. The wobble in this are can be used to calibrate a bit clock in the recording device. This bit clock can subsequently be used to provide timing information when the recording device writes in an area of the recordable optical disc where the wobble is absent.

In a further embodiment of the recordable optical disc all wobble is located more than 28.0 mm from the center of the optical disc.

By locating any wobble further than 28.0 mm away from the center of the disc the recordable optical disk will be recognized as non-recordable by the playback device.

The wobble can for instance be located near the periphery of the recordable optical disc.

Only after the playback has already started will the playback device encounter the wobble when the playback moves towards the periphery of the disc. The playback device currently in use will in such case not stop the playback but continue the playback regardless of the wobble encountered.

Alternatively the wobble can be located so far towards the edge of the recordable optical disc that the wobble will not be encountered until the playback of the material on the disc has finished.

In a further embodiment of the recordable optical disc all wobble is located between 21.0 and 23.4 mm from the center of the optical disc and more than 28.0 mm from the center of the optical disc. By allowing wobble in both the inner zone of the disc between 21.0 and 23.4 mm and in the outer zone between 28.0 mm and the edge of the disc, the addressing information is available to the recorder in an area as large as possible while avoiding detection of any wobble in the disc recognition zone. Furthermore having wobble in multiple areas increases the flexibility of the recorder in deciding where to start the recording, where to end the recording and where to perform a layer jump. Having wobble at those points is beneficial because the exact locations can be determined easily using the wobble while otherwise the positions would have to be determined in another manner, introducing additional delay and loss of accuracy.

In a further embodiment of the recordable optical disc the first recording layer and the second recording layer each comprise a disc recognition zone and a wobble zone. In order to avoid a playback device to locate any wobble in the disc recognition zone both layers preferably lack a wobble in the disc recognition zone. Also, to allow the recording of the disc to quickly resume after changing layers a wobble zone is preferably present in both layers.

In a further embodiment of the recordable optical disc the optical disc comprises a first recording layer and a second recording layer. The above embodiments can also be used advantageously on two layer discs or multi layer discs. The wobble zone can be located on either layer or on both layers, as long as the wobble zone does not overlap with the disk recognition zone of the disc.

A Method for recording an optical disc comprising a groove for storing data, the groove comprising a wobble and a disc recognition zone, where all wobble is located in a wobble zone outside the disc recognition zone, the method comprises the steps of: locating the wobble zone, calibrating a bit clock to the wobble, starting a recording at a starting position, continuing the recording in an area without wobble using the calibrated bit clock.

In order to record the CSS protected material on the record carrier the method of recording must comprise the following steps: - locating the wobble zone. The wobble zone must be used to obtain a bit clock later to be used during the recording phase. calibrating a bit clock to the wobble. The wobble is used to calibrate a bit clock in the recording device. starting a recording at a starting position. The bit clock is maintained and a start position is chosen according to the structure of the disc and depending on the location of the wobble zone. continuing the recording in an area without wobble using the calibrated bit clock. At least the disc recognition zone must be recorded without relying on a wobble in the groove in order to prevent any playback device from detecting a wobble in the disc recognition zone.

In an embodiment of the method the disc recognition zone is located between 23.4 and 28.0 mm from a center of the optical disc.

This implies that the wobble must be located outside the 23.4 to 28.0 mm zone measured from the center of the disc. Since all recorders use this zone between 23.4 and 28.0 mm to determine the type of the optical disc (Read-only / recordable / rewritable , single layer / dual layer) the absence of any wobble from this zone will cause the playback device to determine the type of the recordable optical disk as non-recordable. The algorithm inside the playback device will thus allow the playback of CSS protected copyrighted content because it is misled by the absence of the wobble in the disk recognition zone. In a further embodiment of the method all wobble is located between 21.0 and

23.4 mm from the center of the optical disc. Between 21.0 and 23.4 mm the groove is present and can safely comprise a wobble since no playback device will search in this area for a wobble. The wobble in this are can be used to calibrate a bit clock in the recording device. This bit clock can subsequently be used to provide timing information when the recording device writes in an area of the recordable optical disc where the wobble is absent.

In a further embodiment of the method all wobble is located more than 28.0 mm from the center of the optical disc.

By locating any wobble further than 28.0 mm away from the center of the disc the recordable optical disk will be recognized as non-recordable by the playback device. The wobble can for instance be located near the periphery of the recordable optical disc.

Alternatively the wobble can be located so far towards the edge of the recordable optical disc that the wobble will not be encountered until the playback of the material on the disc has finished. In a further embodiment of the method the recording follows the groove from the starting position towards the periphery of the optical disc.

With the wobble zone located inside between 21.0 and 23.4 mm from the center of the optical disc the calibration is performed in this area and the recording subsequently progresses from the wobble zone towards the periphery of the optical disc, i.e. towards the outer rim or edge of the optical disc. This ensures the fastest recording since no jump to other parts of the disc are required to start recording after calibrating the bit clock in the wobble zone.

In a further embodiment of the method the recording follows the groove from the starting position towards the center of the optical disc. With the wobble zone located more than 28.0 mm from the center of the optical disc the calibration is performed in this area and the recording subsequently progresses from the wobble zone towards the center of the optical disc, i.e. from the outer rim of the disc towards the center of the disc. This ensures the fastest recording since no jump to other parts of the disc are required to start recording after calibrating the bit clock in the wobble zone.

In a further embodiment of the method the starting position is located in the wobble zone.

By locating the starting position in the wobble zone no time is lost by jumps to other parts of the optical disc after the calibration of the bit clock is complete. In a further embodiment of the method the optical disc comprises a first recording layer and a second recording layer.

The above embodiments of the method can also be used advantageously on two layer discs or multi layer discs. The wobble zone can be located on either layer or on both layers, as long as the wobble zone does not overlap with the disk recognition zone of the disc.

In a further embodiment of the method the wobble zone comprises a jump area for facilitating a layer jump. When jumping from one layer to another it is beneficial to jump into the wobble zone of the new layer because in such case there is no need to search for the wobble zone on that layer, calibration can immediately commence and the recording is delayed by the minimum amount possible.

In a further embodiment of the method the recording starts on the first layer and, after a layer jump, the recording follows the groove from the starting position towards the periphery of the optical disc.

After recording on the first layer it is beneficial to perform the recording on the next layer from the center of the disc towards the outer rim of the disc because this requires minimal changes to the current recording devices. In a further embodiment of the method the recording starts on the first layer and, after a layer jump, the recording is continued on the second recording layer following the groove from the layer jump towards the periphery of the recordable optical disc.

In a further embodiment of the method the recording is a disc at once type recording. By performing a disc at once recording the calibrated bit clock can be maintained for the entire recording without the need for a new calibration.

An alternative to disc at once recording is HF- linking which allows the recording device to continue recording on a partly recorded recordable medium instead of being forced to use disc at once recording. A recording device for recording an recordable optical disc comprising a groove for storing data, the groove comprising a wobble and a disc recognition zone where all wobble is located outside the disc recognition zone, the recording device comprising: a wobble zone locating means, a calibrating means for providing a calibrated bit clock calibrated to the wobble of the optical disc, a starting position determining means for determining a starting position, a recording means for recording the data from the starting position and continuing in an area of the optical disc without wobble using the calibrated bit clock provided by the calibrating means. In order to record the CSS protected material on the record carrier the method of recording must comprise the following steps: a wobble zone locating means. This a wobble zone locating means searches for the wobble zone. This can be simple preprogrammed position that needs verification of the presence of a wobble or a more sophisticated search allowing flexibility in the actual location of the wobble zone. a calibrating means for providing a calibrated bit clock calibrated to the wobble of the optical disc. The calibration means is used to calibrate a bit clock in the recording device to the wobble found on the optical disc. - a starting position determining means for determining a starting position. The bit clock is maintained and the starting position determining means is arranged to chose a starting position according to the structure of the disc (for instance single or dual layer disc) and depending on the location of the wobble zone. a recording means for recording the data from the starting position and continuing in an area of the optical disc without wobble using the calibrated bit clock provided by the calibrating means.. At least the disc recognition zone must be recorded by the recording means without relying on a wobble in the groove in order to prevent any playback device from detecting a wobble in the disc recognition zone.

In an embodiment of the recording device the disc recognition zone is located between 23.3 and 30.0 mm from a center of the optical disc.

This implies that the wobble must be located outside the 23.4 to 28.0 mm zone measured from the center of the disc. Since all recorders use this zone between 23.4 and 28.0 mm to determine the type of the optical disc (Read-only / recordable / rewritable , single layer / dual layer) the absence of any wobble from this zone will cause the playback device to determine the type of the recordable optical disk as non-recordable. The algorithm inside the playback device will thus allow the playback of CSS protected copyrighted content because it is misled by the absence of the wobble in the disk recognition zone

In a further embodiment of the recording device the wobble zone locating means is arranged to search for wobble between 21.0 and 23.4 mm from the center of the optical disc.

In a further embodiment of the recording device the wobble zone locating means is arranged to search for wobble more than 28.0 mm from the center of the optical disc.

The wobble can for instance be located near the periphery of the recordable optical disc. Only after the playback has already started will the playback device encounter the wobble when the playback moves towards the periphery of the disc. The playback device currently in use will in such case not stop the playback but continue the playback regardless of the wobble encountered.

In a further embodiment of the recording device the recording means is arranged to follow the groove from the starting position towards the periphery of the optical disc. With the wobble zone located inside between 21.0 and 23.4 mm from the center of the optical disc the calibration is performed in this area and the recording subsequently progresses from the wobble zone towards the periphery of the optical disc, i.e. towards the outer rim or edge of the optical disc. This ensures the fastest recording since no jump to other parts of the disc are required to start recording after calibrating the bit clock in the wobble zone.

In a further embodiment of the recording device the recording means is arranged to follow the groove from the starting position towards the center of the optical disc.

With the wobble zone located more than 28.0 mm from the center of the optical disc the calibration is performed in this area and the recording subsequently progresses from the wobble zone towards the center of the optical disc, i.e. from the outer rim of the disc towards the center of the disc. This ensures the fastest recording since no jump to other parts of the disc are required to start recording after calibrating the bit clock in the wobble zone. In a further embodiment of the recording device the starting position determining means is arranged to locate the starting position in the wobble zone.

By locating the starting position in the wobble zone no time is lost by jumps to other parts of the optical disc after the calibration of the bit clock is complete. In a further embodiment of the recording device the recording device is arranged to record on the optical disc comprising a first recording layer and a second recording layer.

In a further embodiment of the recording device the recording device comprises layer jump means for performing a layer jump in a jump area in the wobble zone on the optical disc. When jumping from one layer to another it is beneficial to jump into the wobble zone of the new layer because in such case there is no need to search for the wobble zone on that layer, calibration can immediately commence and the recording is delayed by the minimum amount possible.

In a further embodiment of the recording device the recorder is arranged to start recording on the first layer and, after a layer jump, to continue recording following the groove from the starting position towards the periphery of the optical disc.

After recording on the first layer it is beneficial to perform the recording on the next layer from the center of the disc towards the outer rim of the disc because this requires minimal changes to the current recording devices. In a further embodiment of the recording device the recorder is arranged to start recording on the first layer and, after a layer jump, to continue recording on the second recording layer following the groove from the layer jump area towards the periphery of the optical disc.

In a further embodiment of the recording device the recorder is arranged to perform a disc at once type recording.

By performing a disc at once recording the calibrated bit clock can be maintained for the entire recording without the need for a new calibration. An alternative to disc at once recording is HF- linking which allows the recording device to continue recording on a partly recorded recordable medium instead of being forced to use disc at once recording.

It is obvious that, while the invention allows the recording of CSS protected material on the recordable optical disc, other, non-CSS protected material can equally be recorded using this invention since the resulting optical disc can be played by a playback device just like an ordinary recordable optical disc as currently available on the market.

When the wording 'recordable optical disc' is used this is to be construed to cover both one-time recordable optical discs and multiple-times recordable optical discs, i.e. rewritable optical discs are covered by this wording as well.

In addition when the description mentions 'absence of wobble', lack of wobble' or 'no wobble' this is to be construed as also covering a wobble with an amplitude so small that it is not detectable by the playback devices in the field.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a conventional optical disc.

Figure 2 shows a first embodiment of an optical disc according to the invention.

Figure 3 shows a second embodiment of an optical disc according to the invention.

Figure 4 shows a cross section of an optical disc according to the first embodiment.

Figure 5 shows a writing sequence for a disc according to the first embodiment. Figure 6 shows a further writing sequence for a disc according to the first embodiment.

Figure 7 shows a further writing sequence for a disc according to the first embodiment. Figure 8 shows a cross section of an optical disc according to the second embodiment.

Figure 9 shows a writing sequence for a disc according to the second embodiment.

Figure 10 shows a recording device for recording data on a disc according to the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Figure 1 shows a conventional optical disc.

The recordable optical disc 1 comprises a groove 2 spiraling from a center zone 4 near the center 3 of the disci towards the periphery 6 or edge 6 of the optical disc.

The groove 2 comprises a wobble, also in the disc recognition zone 4. The disc recognition zone 4 is indicated in the drawing by the cross hatched area and is not to scale to improve the clarity of figure 1. Also in the other figures the various zones will not be to scale to improve the clarity of the figures. The disc recognition zone lies between 23.4 and 28.0 mm measured from the center of the disc and its size is defined not so much by a standard but by the actual behavior of the playback devices in the field.

However 23.4 to 28.0 mm covers all current playback devices with a few exceptions.

A playback device will use the disc recognition zone to recognize the type of optical disc before proceeding. When a wobble is found the optical disc is assumed to be a recordable disc and additionally CSS protected material is found on the disc the playback of this CSS protected material will be refused.

Figure 2 shows a first embodiment of an optical disc according to the invention. In order to avoid the recognition of the recordable optical disci as a recordable disc the disc recognition zone 4 must be free of wobble, yet wobble is needed to ensure proper recording, for instance a proper bit clock is derived from the wobble frequency encountered on the optical disc 1. One way of providing a wobble zone outside the disc recognition zone 4 is by providing a wobble zone 7 more than 28.0 mm away from the center 3 of the disc.

The recording device can retrieve the wobble from this wobble zone 7 near the edge 6 of the disc 1 and subsequently use the wobble to for instance calibrate a bit clock. The actual recording can use this bit clock and can start either in the wobble zone 7 and continue towards the center 3 of the disc 1 by simply reversing the image used for recording. Because a normal image for recording assumes the bits to be written from the center 3 towards the edge 6 of the disc a simple reversal of the bit sequence allows the reversal of the recording direction. Hence the recording can immediately start from a starting position in the wobble zone 7.

In order to avoid the recognition of the recordable optical disci as a recordable disc the disc recognition zone 4 must be free of wobble, yet wobble is needed to ensure proper recording, for instance a proper bit clock is derived from the wobble frequency encountered on the optical disc 1. One way of providing a wobble zone outside the disc recognition zone 4 is by providing a wobble zone 8 less than 23.4 mm away from the center 3 of the disc.

The recording device can retrieve the wobble from this wobble zone 8 near the center 3 of the disc 1 and subsequently use the wobble to, for instance, calibrate a bit clock.

The actual recording can use this bit clock and can start either in the wobble zone 8 and continue towards the edge 6 of the disc 1. Hence the recording can immediately start from a starting position in the wobble zone 8.

Only half of the optical disc 1 is shown. On the left side the hole at the center 3 of the disc 1 is shown. The disc 1 is shown with a first layer 11 and a second layer 12. The disc recognition zone 4 is free of wobble to ensure that the recordable optical disc is not recognized as a recordable optical disk but as a read only disc. The cross section of figure 4 corresponds to the optical disc shown in figure 2, i.e. the wobble zone 7 is located near the edge 6 of the optical disc 1.

Figure 5 shows a writing sequence for a disc according to the first embodiment. The recording device first searches the wobble zone 7 using the wobble zone locating means and finds this wobble zone 7 near the edge 6 of the optical disc 1, i.e. more than 28 mm away from the center 3 of the optical disc 1. This can be simple preprogrammed position that needs verification of the presence of a wobble or a more sophisticated search allowing flexibility in the actual location of the wobble zone.

Subsequently the calibrating means of the recording device is used calibrating the bit clock of the recording device to the wobble in the wobble zone 7 of the optical disc 1.

Subsequently the starting position determining means of the recording device is used for determining a starting position. The bit clock is maintained and the starting position determining means is arranged to chose a starting position according to the structure of the disc (for instance single or dual layer disc) and depending on the location of the wobble zone 7.

The recording means in the recording device is used for recording the data from the starting position, for instance located in the wobble zone 7 and continuing in an area of the optical disc without wobble, such as the disc recognition zone 4, using the calibrated bit clock provided by the calibrating means. This is indicated in figure 5 by the first arrow 50. At least the disc recognition zone must be recorded by the recording means without relying on a wobble in the groove in order to prevent any playback device from detecting a wobble in the disc recognition zone. For a single layer disc, effectively a disc 1 as shown in figure 5 without the second layer 12, the recording is complete when all material has been recorded.

On a dual layer disc, i.e. a disc including the second layer 12, the recording may continue by performing a layer jump from the first layer 11 to the second layer 12 as indicated by the second arrow 51. As shown in figure 5 after the layer jump the recording continues from an inner zone of the second layer 12 towards the edge 6 of the disc 1 as indicated by the third arrow 52. An optional wobble zone 19 on the second layer 12 that would facilitate the recalibration of the bit clock at the beginning of the recording on the second layer 12.

Figure 6 shows a further writing sequence for a disc having a disc recognition zone 4, 18on each recording layer 11, 12 and having wobble zones 16, 17 in the inner zone 5 and wobble zones 7, 19 the outer zone between 28.0 mm from the center of the disc 1 and the edge of the disc 1.

Wobble zones 7, 16, 17, 19 are present on both layers 11, 12. The areas of wobble and the disc recognition zones are, for this example, chosen to be identical on both layers 11, 12. It is self evident that while this is an advantageous distribution of disc recognition zones 4,18 and wobble zones 7, 16, 17, 19 other positions and sizes of the wobble zones are also feasible.

In this embodiment the calibration is performed first in the wobble zone 16 in the inner zone of the first layer 11 near the center 3 of the disc 1. Subsequently the starting point is positioned in the inner zone 5 or the disc recognition zone 4. The recording commences in the direction of the edge 6 of the disc 1 in the first layer 11 as indicated by a first arrow 61 in figure 6. In effect the recording is towards and, depending on the amount of data, into the wobble zone 7 in the outer zone. When the recording reaches a point where a jump to the second recording layer 12 is required, the layer jumping means performs a layer jump as indicated by the second arrow 62. After this layer jump the recording continues back towards the center of the disc 1 in the second layer 12 as indicated by the third arrow 63.

It is beneficial to have a wobble zone 19 located in the second layer 12 very close to or directly above the layer jump position. Another option is to position the wobble zone 19 above the first wobble zone 7. A layer jump causes the optical beam of the recording device to be positioned in the wobble zone 19 on the second layer 12, removing the need for the recording device to use the wobble zone location means on the second layer 12 to locate the wobble zone 19.

Figure 6 further shows the second disc recognition zone 18 located on the second layer 12 advantageously located directly above the first disc recognition zone 4. To avoid problems with playback devices that check both layers for information it is advantageous to ensure that wobble is also absent from the second disc recognition zone 18 on the second layer 12.

Figure 7 shows a further writing sequence for a disc according to the first embodiment.

In this embodiment the calibration is performed first in the wobble zone 7 of the first layer 11 near the edge 6 of the disc 1. Subsequently the starting point is positioned in or near the wobble zone 7 and the recording commences in the direction of the center 3 of the disc 1 in the first layer as indicated by a first arrow 61 in figure 6. In effect the recording is towards the inner zone 5. When the recording reaches a point where a jump to the second recording layer 12 is required, the recording device repositions the recording beam in an area that allows a layer jump to be performed, for instance in the wobble zone 7 on the first layer and / or below an optional second wobble zone 19. Subsequently the layer jumping means performs a layer jump as indicated by the second arrow 62. After this layer jump the recording continues back towards the center of the disc 1 in the second layer 12 as indicated by the third arrow 63.

It is beneficial to have a second wobble zone 19 located in the second layer 12 very close or directly above the layer jump position. Another option is to position the second wobble zone 19 above the first wobble zone 7. The layer jump advantageously causes the recording device to be positioned in the second wobble zone 19 on the second layer 12, removing the need for the recording device to use the wobble zone location means on the second layer 12 to locate the second wobble zone 19.

Another option is to position the second wobble zone 19 in the inner zone on the second layer 12, i.e. between 21.0 and 23.4 mm from the center on the second layer 12. In that case the layer jump occurs when the recording on the first layer 11 reaches a point on the first layer 11 directly below the second wobble zone 19.

Figure 7 further shows an optional second disc recognition zone 18 located on the second layer 12. To avoid problems with playback devices that check both layers for information it is advantageous to ensure that wobble is also absent from the second disc recognition zone 18 on the second layer 12.

Figure 8 shows a cross section of an optical disc according to the second embodiment.

Only half of the optical disc 1 is shown. On the left side the hole at the center 3 of the disc 1 is shown. The disc 1 is shown with a first layer 11 and a second layer 12. The disc recognition zone 4 is free of wobble to ensure that the recordable optical disc is not recognized as a recordable optical disk but as a read only disc. The cross section of figure 4 corresponds to the optical disc shown in figure 3, i.e. the wobble zone 8 is located near the center 3 of the optical disc 1. Figure 9 shows a writing sequence for a disc according to the second embodiment.

The recording device first searches the wobble zone 8 using the wobble zone locating means and finds this wobble zone 8 in the inner zone 5 near the center 3 of the optical disc 1, i.e. for instance between 21.0 and 23.4 mm from the center 3 of the optical disc 1. This can be simple preprogrammed position that needs verification of the presence of a wobble or a more sophisticated search allowing flexibility in the actual location of the wobble zone.

Subsequently the calibrating means of the recording device is used calibrating the bit clock of the recording device to the wobble in the wobble zone 8 of the optical disc 1. Subsequently the starting position determining means of the recording device is used for determining a starting position. The bit clock is maintained and the starting position determining means is arranged to chose a starting position according to the structure of the disc (for instance single or dual layer disc) and depending on the location of the wobble zone 8. In the present figure an advantageous starting position is near or in the wobble zone 8.

The recording means in the recording device is used for recording the data starting from the starting position, for instance located in the wobble zone 8 and continuing in an area of the optical disc without wobble, such as the disc recognition zone 4, using the calibrated bit clock provided by the calibrating means. At least the disc recognition zone must be recorded by the recording means without relying on a wobble in the groove in order to prevent any playback device from detecting a wobble in the disc recognition zone 4.

The starting point is positioned in the inner zone 5 or the disc recognition zone 4 and the recording commences in the direction of the edge 6 of the disc 1 in the first layer 11 as indicated by a first arrow 61 in figure 9.

For a single layer disc, effectively a disc 1 as shown in figure 9 without the second layer 12, the recording is complete when all material has been recorded.

On a dual layer disc, i.e. a disc including the second layer 12, the recording may continue by performing a layer jump from the first layer 11 to the second layer 12. When the recording reaches a point where a jump to the second recording layer 12 is required, the layer jumping means performs a layer jump as indicated by the second arrow 62. After this layer jump the recording continues back towards the center of the disc 1 in the second layer 12 as indicated by the third arrow 63.

It is beneficial to have a second wobble zone 19 located in the second layer 12 very close or directly above the layer jump position as shown in figure 9. Another option is to position the second wobble zone above the first wobble zone 7. The recording continues in that case on the first layer 11 into the first wobble zone 7 and a layer jump causes the recording device to be positioned in the second wobble zone 19 on the second layer 12, removing the need for the recording device to use the wobble zone location means on the second layer 12 to locate the second wobble zone 19.

Figure 9 further shows an optional second disc recognition zone 18 located on the second layer 12. To avoid problems with playback devices that check both layers for information it is advantageous to ensure that wobble is also absent from the second disc recognition zone 18 on the second layer 12. Figure 10 shows a recording device for recording data on a disc according to the invention.

The recording device 100 for recording CSS protected material in a recordable optical disc comprises a central processor 102, a wobble zone locating means 104, a calibrating means 106, a recording means 105 and a starting position determining means 103.

The central processor 102 in the recording device first instructs the wobble zone locating means 104 to search the wobble zone 7. When the wobble zone locating means 104 finds this wobble zone 7 it reports the position or range at which the wobble zone was found back to the central processor 102. The wobble zone locating means can use a simple preprogrammed position that only needs verification of the presence of a wobble or a more sophisticated search method allowing flexibility in the actual location of the wobble zone and allowing for variations between discs. When the central processor 102 receives the position or range of the wobble zone from the wobble zone locating means 104 it subsequently instructs the calibration means 106 to calibrate the bit clock of the recording device to the wobble in the wobble zone found on the optical disc 101. The calibration means 106 ensures that a constant bit clock is available to the recording device 100 for use during the recording process. Once the calibration is completed the calibration means 106 reports the result of the calibration to the central processor 102. The central processor then instructs the starting position determining means 103 to determine a suitable starting position from which the recording can commence, given the detected structure of the disc 101 (for instance depending on whether it is a single or dual layer disc where the wobble zone and the jumping position is located). The starting position determining means 103 provides the central processor 102 with a suitable starting position and the central processor 102 then instructs the recording means 105 to start the recording from the starting position. The recording means 105 uses the bit clock provided by the calibration means 106 for the recording.

The starting position determining means is arranged to chose a starting position according to the structure of the disc (for instance single or dual layer disc) and depending on the location of the wobble zone 7.

The recording means in the recording device is used for recording the data from the starting position, for instance located in the wobble zone 7 and continuing in an area of the optical disc without wobble, such as the disc recognition zone 4, using the calibrated bit clock provided by the calibrating means. At least the disc recognition zone must be recorded by the recording means without relying on a wobble in the groove in order to prevent any playback device from detecting a wobble in the disc recognition zone. For a single layer disc, effectively a disc 1 as shown in figure 5 without the second layer 12, the recording is complete when all material has been recorded.

On a dual layer disc, i.e. a disc including the second layer 12, the recording may continue by performing a layer jump from the first layer 11 to the second layer 12. As shown in figure 5 after the layer jump the recording continues from an inner zone of the second layer 12 towards the edge 6 of the disc 1.

Claims

CLAIMS:

1. Recordable optical disc comprising a groove for storing data, the groove comprising a wobble and a disc recognition zone, characterized in that all wobble is located outside the disc recognition zone.

2. Recordable optical disc as claimed in claim 1, where the disc recognition zone is located between 23.4 and 28.0 mm from a center of the optical disc.

3. Recordable optical disc as claimed in claim 2, where all wobble is located between 21.0 and 23.4 mm from the center of the optical disc.

4. Recordable optical disc as claimed in claim 2, where all wobble is located more than 28.0 mm from the center of the optical disc.

5. Recordable optical disc as claimed in claim 2, where all wobble is located between 21.0 and 23.4 mm from the center of the optical disc and more than 28.0 mm from the center of the optical disc.

6. Recordable optical disc as claimed in claim 3, 4 or 5, where the optical disc comprises a first recording layer and a second recording layer.

7. Recordable optical disc as claimed in claim 6, where the first recording layer and the second recording layer each comprise a disc recognition zone and a wobble zone.

8. Method for recording a recordable optical disc comprising a groove for storing data, the groove comprising a wobble and a disc recognition zone, where all wobble is located in a wobble zone outside the disc recognition zone, the method comprising the steps of: locating the wobble zone, calibrating a bit clock to the wobble, starting a recording at a starting position, continuing the recording in an area without wobble using the calibrated bit clock.

9. Method as claimed in claim 8, where the disc recognition zone is located between 23.4 and 28.0 mm from a center of the recordable optical disc.

10. Method as claimed in claim 9, where all wobble is located between 21.0 and 23.4 mm from the center of the recordable optical disc.

11. Method as claimed in claim 9, where all wobble is located more than 28.0 mm from the center of the recordable optical disc.

12. Methods as claimed in claim 10 or 11, where the recording follows the groove from the starting position towards the periphery of the recordable optical disc.

13. Method as claimed in claim 10 or 11, where the recording follows the groove from the starting position towards the center of the recordable optical disc.

14. Method as claimed in claim 12 or 13, where the starting position is located in the wobble zone.

15. Method as claimed in claim 10, 11, 12, 13 or 14, where the recordable optical disc comprises a first recording layer and a second recording layer.

16. Method as claimed in claim 15, where the wobble zone comprises a jump area for facilitating a layer jump.

17. Method as claimed in claim 13 and 15, where the recording starts on the first layer and, after a layer jump, the recording follows the groove from the starting position towards the periphery of the recordable optical disc.

18. Method as claimed in claim 12 and 15, where the recording starts on the first layer and, after a layer jump, the recording is continued on the second recording layer following the groove from the layer jump towards the periphery of the recordable optical disc.

19 Method as claimed in any one of the claims 9 to 18, where the recording is a disc at once type recording.

20. Recording device for recording a recordable optical disc comprising a groove for storing data, the groove comprising a wobble and a disc recognition zone where all wobble is located outside the disc recognition zone, the recording device comprising: a wobble zone locating means, a calibrating means for providing a calibrated bit clock calibrated to the wobble of the recordable optical disc, - a starting position determining means for determining a starting position, a recording means for recording the data from the starting position and continuing in an area of the recordable optical disc without wobble using the calibrated bit clock provided by the calibrating means.

21. Recording device as claimed in claim 20, where the disc recognition zone is located between 23.4 and 28.0 mm from a center of the recordable optical disc.

22. Recording device as claimed in claim 21, where the wobble zone locating means is arranged to search for wobble between 21.0 and 23.4 mm from the center of the recordable optical disc.

23. Recording device as claimed in claim 21, where the wobble zone locating means is arranged to search for wobble more than 28.0 mm from the center of the recordable optical disc.

24. Recording device as claimed in claim 22 or 23, where the recording means is arranged to follow the groove from the starting position towards the periphery of the recordable optical disc.

25. Recording device as claimed in claim 22 or 23, where the recording means is arranged to follow the groove from the starting position towards the center of the recordable optical disc.

26. Recording device as claimed in claim 24 or 25, where the starting position determining means is arranged to locate the starting position in the wobble zone.

27. Recording device as claimed in claim 22, 23, 24, 25 or 26, where the recording device is arranged to record on the recordable optical disc comprising a first recording layer and a second recording layer.

28. Recording device as claimed in claim 27, where the recording device comprises layer jump means for performing a layer jump in a jump area in the wobble zone on the recordable optical disc.

29. Recording device as claimed in claim 24 and 27, where the recorder is arranged to start recording on the first layer and, after a layer jump, to continue recording following the groove from the starting position towards the periphery of the recordable optical disc.

30. Recording device as claimed in claim 25 and 27, where the recorder is arranged to start recording on the first layer and, after a layer jump, to continue recording on the second recording layer following the groove from the layer jump area towards the periphery of the recordable optical disc.

31. Recording device as claimed in any one of the claims 21 to 30, where the recorder is arranged to perform a disc at once type recording.