Optical disk provided with bar code

0001The invention refers to an optical disk as set forth in the preamble of claim 1 and a reproduction apparatus for reproducing such optical disk. An optical disk and reproduction apparatus of this kind are known from EP-A-0 741 382.

0002In the manufacturing process of optical disks, it has been commonly practiced to record a serial number, lot number, etc. on each optical disk in the form of a barcode.

0003Since such information cannot be written to a pit information area of the optical disk, it has been practiced to write the barcoded information to a non-information area, or unused space on the optical disk.

0004When reproducing (playing back) such an optical disk, the pit information is read by an optical pickup; to read the barcoded information such as serial number, etc. recorded in the non-information area, however, a separate reading device has been used, Increasing complexity of the reproduction apparatus.

0005However, there are also optical disks available which do not comprise such barcode-like mark. If the reproduction apparatus is designed to utilize a barcode-like mark provided on the disk operation of the reproduction apparatus may cause problems if such mark is missing on the disk, inserted into the reproduction apparatus.

0006It is the object of the invention to provide an optical disk of the afore-mentioned kind which facilitates operation of a reproduction apparatus. It is another object of the invention to provide a respective reproduction apparatus.

0007These objects are obtained by the features of claims 1 and 3, respectively. Preferred embodiments thereof are subject matter of the dependent claims.

0008The present invention provides an optical disk wherein a data area is provided for holding therein an identifier for indicating the presence or absence of a barcode-like mark on the disk so that the operation of the disk player reproducing the disk may be controlled dependent on the presence or absence of the barcode-like mark.

0009The invention is now explained with reference to the accompanying drawings. <ul id="ul0001" list-style="none" compact="compact"><li>Figure 1 is a diagram showing a disk manufacturing process and a secondary recording process;</li><li>Figure 2(a) is a top plan view of a disk, (b) is an enlarged top plan view of a portion of the disk, (c) is a further enlarged top plan view of a portion of the disk, (d) is a transverse section view of the disk, and (e) is a wave form diagram of reproduced signal;</li><li>Figure 3 is a diagram illustrating a piracy prevention algorithm;</li><li>Figure 4 is a diagram showing a procedure for playing back a PCA area in a tracking ON condition;</li><li>Figure 5 is a diagram showing the arrangement of stripes on a disk and the contents of control data;</li><li>Figure 6 is a diagram showing a stripe area and an address area on a disk;</li><li>Figure 7 is a flow chart illustrating how control mode is switched between CAV and CLV when playing back stripes, and</li><li>Figure 8 is a diagram showing a procedure for reading control data for playback.</li></ul>

0010In the description hereinafter given, position information for piracy prevention, which is a form of ID, is taken as an example of information to be barcoded.

0011We will first describe a general process flow from disk manufacturing to the completion of an optical disk by using the flowchart of Figure 1.

0012In this patent specification, laser trimming is also referred to as laser marking, while a nonreflective optical marking portion is simply referred to as the barcode, stripe, marking, or optical marking or, sometimes, as the physical ID unique to a disk.

0013First, the software company performs software authoring in software production process 820. The completed software is delivered from the software company to the disk manufacturing factory. In disk manufacturing process 816 at the disk manufacturing factory, the completed software is input in step 818a, a master disk is produced (step 818b), disks are pressed (steps 818e, 818g), reflective films are formed on the respective disks (steps 818f, 818h), the two disks are laminated together (step 818i), and a ROM disk such as a DVD or CD is completed (step 818m, etc.).

0014The thus completed disk 800 is delivered to the software maker or to a factory under control of the software maker, where, in secondary recording process 817, an anti-piracy marking 584, such the one shown in Figure 2, is formed (step 819a), and accurate position information of this mark is read by a measuring means (step 819b) to obtain the position information which serves as the physical feature information of the disk. This physical feature information of the disk is encrypted in step 819c. The encrypted information is converted to a PE-RZ-modulated signal which is then recorded in step 819d as a barcode signal on the disk by using a laser. The disk physical feature information may be combined together with software feature information for encryption in step 819c.

0015By removing the reflective film by laser light, in the manufacturing process of the disk, a waveform easily distinguishable from that of a pit signal is obtained when reproducing the disk. Rather than forming the barcode of the invention by removing the reflective film by laser light, the barcode may be formed by changing the shape of pits on the master disk.

0016Next, the constitution and operation of a reproduction apparatus (player) for reproducing the thus completed optical disk on a player will be described with reference to Figure 3.

0017In the figure, the construction of an optical disk 9102 will be described first. A marking 9103 is formed on a reflective layer (not shown) deposited on the optical disk 9102. In the manufacturing process of the optical disk, the position of the marking 9103 was detected by position detecting means, and the detected position was encrypted as marking position information and written on the optical disk in the form of a barcode 9104.

0018Position information reading means 9101 reads the barcode 9104, and decrypting means 9105 contained therein decrypts the contents of the barcode for output. Marking reading means 9106 reads the actual position of the marking 9103 and outputs the result. Comparing/judging means 9107 compares the decrypted result from the decrypting means 9105 contained in the position information reading means 9101 with the result of reading by the marking reading means 9106, and judges whether the two agree within a predetermined allowable range. If they agree, a reproduction signal 9108 for reproducing the optical disk is output; if they do not agree, a reproduction stop signal 9109 is output. Control means (not shown) controls the reproduction operation of the optical disk in accordance with these signals; when the reproduction stop signal is output, an indication to the effect that the optical disk is an illegal duplicated disk is displayed on a display (not shown) and the reproduction operation is stopped. In the above operation, it will be recognized that it is also possible for the marking reading means 9106 to use the decrypted result from the decrypting means 9105 when reading the actual position of the marking 9103. Namely in this case, the marking reading means 9106 checks whether the marking is actually located in the position on the optical disk indicated by the position information which is decrypted by the decrypting means 9105.

0019Thus the reproduction apparatus of the above construction can detect an illegally duplicated optical disk and stop the reproduction operation of the disk, and can prevent illegal duplicates practically .

0020We will next describe features of the optical disk format with a barcode formed in the above manner, tracking control methods, and rotational speed control methods that can be used when playing back the optical disk.

0021We will first describe the features of the optical disk format with a barcode formed according to the present embodiment, while dealing with an example of a condition that permits tracking control during playback (this condition is also referred to as the tracking ON condition). A playback operation using tracking control is shown in Figure 4, and its details will be given later.

0022In the case of a DVD disk, all data are recorded in pits with CLV, as shown in Figure 5. Stripes 923 (forming a barcode) are recorded with CAV. CLV recording means recording with constant linear velocity, while CAV recording means recording with constant angular velocity.

0023In the present invention, the stripes 923 are recorded with CAV, superimposed on a pre-pit signal in a lead-in data area holding an address which is recorded with CLV. That is, the data is overwritten with the stripes.

0024The pre-pit signal area maps into all the data areas where pits are formed. The prescribed region of the pre-pit signal area corresponds to an inner portion of the optical disk; this region is also called a post-cutting area (PCA). In this PCA area, the barcode is recorded with CAV, superimposed on pre-bit signals. In this way, the CLV data is recorded with a pit pattern from the master disk, while the CAV data is recorded with laser-removed portions of the reflective film. Since the barcode data is written in overwriting fashion, pits are recorded between the barcode stripes IT, 2T, and 3T. Using this pit information, optical head tracking is accomplished, and Tmax or Tmin of the pit information can be detected; therefore, motor rotational speed is controlled by detecting this signal. To detect Tmin, the relation between the trimming width t of stripe 923a and the pit clock T (pit) should be t > 14T (pit), as shown in Figure 5, to achieve the above effect. If t is shorter than 14T, the pulse width of the signal from the stripe 923a becomes equal to the pulse width of the pit signal, and discrimination between them is not possible, so that the signal from the stripe 923a cannot be demodulated. To enable pit address information to be read at the same radius position as the stripes, an address area 944 is provided longer than a unit of one address of pit information, as shown in Figure 6; address information can thus be obtained, making it possible to jump to the desired track. Furthermore, the ratio of the stripe area to the non-stripe area, that is, the duty ratio, is made less than 50%, i.e., T(S) < T(NS) ; since the effective reflectivity decreases only by 6 dB, this has the effect of ensuring stable focusing of the optical head.

0025Next, we will describe an example of a condition in which tracking control cannot be applied during playback (this condition is also referred to as the tracking OFF condition).

0026Since the stripes 923 are written over pits, interrupting pit signals and preventing correct playback of the pit data, tracking control may not be possible on some players. In such players, the strips 923, which are CAV data, can be read by the optical pickup by applying rotational control using a rotational pulse from a Hall element, etc. in the motor 17.

0027Figure 7 shows a flowchart illustrating a procedure for operations in a playback apparatus when pit data in the optical tracks in the stripe area cannot be correctly played back.

0028In Figure 7, when a disk is inserted in step 930a, the optical head is moved by a prescribed distance to the inner portion in step 930b. The optical head is thus positioned on the area where the stripes 923 of Figure 5 are recorded.

0029Here, it is not possible to correctly playback data from all the pits recorded in the stripe area 923. In this case, therefore, usual rotation phase control cannot be applied for the playback of the pit data recorded with CLV.

0030In step 930c, rotational speed control is applied by using a rotational sensor of a Hall element in the motor or by measuring the T(max) or T(min) or frequency of a pit signal. If it is determined in step 930i that there are no stripes, the process jumps to step 930f. If there are stripes, the barcode is played back in step 930d, and when playback of the barcode is completed in step 930e, the optical head is moved in step 930f to an outer area where no stripes are recorded. In this area, since no stripes are recorded, the pits are played back correctly and accurate focus and tracking servo are achieved. Since the pit signal can be played back, usual rotation phase control can be performed to rotate the disk with CLV. As a result, in step 930h, the pit signal is played back correctly.

0031By switching between the two rotation control modes, i.e., the rotational speed control and the rotation phase control by pit signals, the effect is obtained that two different kinds of data, barcode stripe data and pit-recorded data, can be played back. Since the stripes are recorded in the innermost area, switching means measures the radius position of the optical head from the optical head stopper or from the address of a pit signal, and based on the result of the measurement, correctly performs switching between the two rotation control modes.

0032In a playback method for playing back an optical disk on which a stripe presence/absence identifier 937 is not defined, tracking is not applied in the stripe area on an optical disk of this type, so that, it takes time to distinguish between a stripe pattern legally formed on the disk and an irregular pattern caused by scratches on the disk surface. Therefore, regardless of whether the stripes are recorded or not, the playback procedure has to perform a stripe reading operation first, to check the presence or absence of stripes or whether the stripes are recorded in the inner portion of the optical disk. This may cause a problem in that an extra time is required before the data can be actually played back. The invention improves on this point.

0033First, as shown in Figure 8, when an optical disk is inserted, control data is played back in step 940a. Usually, physical feature information and attribute information of the optical disk are recorded as control data in a control data area. The physical feature information includes, for example, information indicating that the optical disk is a laminated-type disk of a two-layer, single-sided structure.

0034In the present invention, as shown in Figure 5, the control data recorded in the control data area 936 of the optical disk contains a PCA stripe presence/absence identifier 937 recorded as a pit signal. Therefore, the optical head is first moved, in step 940n, to an outer area where the control data is recorded. And then the optical head moves inwardly jumping across a plurality of tracks until reaching the control data area 936. And then in step 940a, the control data is played back. It can thus be checked whether the stripes are recorded or not. If, in step 940b, the stripe presence/absence identifier is 0, the process proceeds to step 940f to initiate rotation phase control for normal playback with CLV. On the other hand, if, in step 940b, the presence/absence identifier 937 is 1, then the process proceeds to step 940h to check the presence or absence of a reverse-side record identifier 948 which indicates that the stripes are recorded on the side opposite from the side being played back, that is, on the reverse side. If the stripes are recorded on the reverse side, the process proceeds to step 940i to play back the recording surface on the reverse side of the optical disk. If the reverse side cannot be automatically played back, an indication is output for display, to urge the user to turn over the disk. If it is determined in step 940h that the stripes are recorded on the side being played back, the process proceeds to step 940c, where the head is moved to the stripe area 923 in the inner portion of the disk, and in step 940d, the control mode is switched to rotational speed control to play back the stripes 923 with CAV rotation. If the playback is completed in step 940e, then in step 940f the control mode is switched back to rotation phase control for CLV playback and the optical head is moved to the outer portion of the disk to play back pit signal data.

0035Since the stripe presence/absence identifier 937 is recorded in the pit area holding the control data, etc., as described above, the invention has the effect of being able to play back the stripes more reliably and more quickly compared to a playback method which does not refer to a stripe presence/absence identifier.

0036Further, as shown in Figure 5, the control data also contains an additional stripe data presence/absence identifier and a stripe recording capacity. That is, after recording first stripes on an optical disk, additional stripes can be recorded in an empty, unrecorded portion of the area. The first recorded stripes will be referred to as the first set of stripes, and the additionally recorded stripes as the second set of stripes. With this configuration, when the first set of stripes 923 is already recorded by trimming, as shown in Figure 5, the capacity of the available space for trimming the second set of stripes 938 can be calculated. Accordingly, when the recording apparatus performs trimming to record the second set of stripes, the control data provides an indication of how much space is available for additional recording; this prevents the possibility of destroying the first set of stripes by recording more than 360° over the area. Furthermore, as shown in Figure 5, a gap 949 longer than one pit-signal frame length is provided between the first set of stripes 923 and the second set of stripes 938; this serves to prevent the previously recorded trimming data from being destroyed.