Method and apparatus for performing target search on optical storage disc

An optical storage disc stores storage information and includes track information. A method for performing a target search on the optical storage disc includes: generating a first intermediate signal according to a readout signal generated by an optical storage device reading the storage information; generating a second intermediate signal according to the track information carried within the readout signal; generating a hybrid address signal according to the first intermediate signal and the second intermediate signal; and performing the target search on the optical storage disc according to the hybrid address signal and a target address set by the optical storage device.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to a method and an apparatus for performing target search on an optical storage disc, and more particularly, to a method and an apparatus for performing target search on an optical storage disc according to a hybrid address signal.

2. Description of the Prior Art

As the data processing speed of computer systems greatly increases and the requirement of more massive data storage is correspondingly introduced, optical storage discs that are cost-effective and compact while having larger storage volumes and high access speeds have become popular storage media. Accordingly, an optical storage device for accessing the optical storage discs becomes essential and necessary. Digital Versatile Discs (DVDs) and DVD drives are typical of the optical storage discs and optical storage devices mentioned above, respectively. When an optical storage device is going to read specific data within an optical storage disc, the optical storage device firstly performs a target search on the optical storage disc to find a location of the specific data. The optical storage device then compares address information read through an optical pickup module of the optical storage device from the optical storage disc with a target address. If the address information read through the optical pickup module matches with the target address, the target search is complete.

According to a prior art method of target search, the address information can be address information of physical wobbles on the optical storage disc, i.e. physical addresses. Normally, pre-grooves of a blank optical storage disc include the information of the physical addresses. However, it is not easy to read the physical wobbles if data is already written on the optical storage disc since the data writing process usually degrades the quality of the physical wobbles. As a result, the optical storage device is either unable to perform the target search or performs the target search inaccurately.

According to another prior art method of target search, the address information can be address information corresponding to storage information stored within the optical storage disc, i.e. logical addresses. However, the accuracy of the logical addresses corresponds to the accuracy of a location of the storage information stored within the optical storage disc. If data recording shift when writing the storage information to the optical storage disc occurs, the target search performed according to the logical addresses will be inaccurate due to the data recording shift.

As mentioned above, neither the prior art method of target search according to the physical addresses nor the prior art method of target search according to the logical addresses will ensure that the optical storage device correctly performs the target search.

SUMMARY OF INVENTION

It is therefore an objective of the present invention to provide a method and an apparatus for performing a target search on an optical storage disc according to a hybrid address signal.

The present invention provides a method for performing a target search on an optical storage disc. The optical storage disc stores storage information, and the optical storage disc includes track information. The method includes: generating a first intermediate signal according to a readout signal generated by an optical storage device reading the storage information; generating a second intermediate signal according to the track information carried within the readout signal; generating a hybrid address signal according to the first and second intermediate signals, wherein the hybrid address signal corresponds to the first and second intermediate signals, and the hybrid address signal is synchronized with the second intermediate signal; and performing the target search on the optical storage disc according to the hybrid address signal and a target address set by the optical storage device.

Accordingly, the present invention further provides a circuit installed in an optical storage device for performing a target search on an optical storage disc. The optical storage disc stores storage information, and the optical storage disc includes track information. The circuit includes: a first signal generator for generating a first intermediate signal according to a readout signal generated by the optical storage device reading the storage information; a second signal generator for generating a second intermediate signal according to the track information carried within the readout signal; a third signal generator electrically connected to the first and second signal generators for generating a hybrid address signal according to the first and second intermediate signals, wherein the hybrid address signal corresponds to the first and second intermediate signals, and the hybrid address signal is synchronized with the second intermediate signal; and a target search module electrically connected to the third signal generator for performing the target search on the optical storage disc according to the hybrid address signal and a target address set by the optical storage device.

It is an advantage of the present invention that the present invention method and device generate the hybrid address signal according to physical addresses and logical addresses and perform the target search according to the hybrid address signal so that the present invention provides better performance in contract to the prior art. When interruption of decoding the physical addresses occurs, the present invention method and device continuously generate the second intermediate signal according to a period thereof, i.e. the period of the previously generated second intermediate signal, so that the hybrid address signal is continuously generated. Therefore, the present invention ensures that the target search performed by the optical storage device according to the hybrid address signal is correct.

DETAILED DESCRIPTION

Please refer toFIG. 1andFIG. 2for a preferred embodiment of the present invention.FIG. 1is a flowchart of a method for performing a target search according to the present invention.FIG. 2illustrates a circuit201installed in an optical storage device200for performing the target search on an optical storage disc102. The optical storage device200includes a micro-processing unit (MPU)104and an optical pickup module110. In the present embodiment, the optical storage disc102is a Digital Versatile Disk (DVD)102and the optical storage device200is a DVD drive200, wherein the DVD102and the DVD drive200are well known in the art. The optical storage disc102stores storage information103s, wherein the storage information103sincludes logical addresses. With a viewpoint regarding modulation format, a readout signal generated by the optical pickup module110reading the storage information103swithin the optical storage disc102is referred to as an eight to fourteen modulation (EFM) signal. In addition, the optical storage disc102includes track information103t, i.e. information of physical wobbles well known in the art. With a viewpoint regarding waveforms, the readout signal is also referred to as a push-pull signal PP.

As shown inFIG. 2, the circuit201includes a sector identification signal generator210, a physical synchronization signal generator220, a counting module230, an identification sampler (ID sampler)240, and a target search module250. The sector identification signal generator210includes a data path unit (DPU)212and a sector identification decoder214. The physical synchronization signal generator220includes a slicer222, a physical address demodulating circuit224, and a sync pattern decoding circuit226. The counting module230includes a slicer232, a de-glitch unit234, and a counter236. In addition, the ID sampler240includes an identification sampling signal generating unit242and a hybrid address signal generating unit244. The present invention method is described using the following steps according to the preferred embodiment, however, the order of the steps is not a limitation to the present invention.

Step10b:Decode the storage information103scarried within the demodulated signal DemEFM according to the sector synchronization signal DVD_S0using the sector identification decoder214to generate a sector identification signal SECTOR_ID, wherein the sector identification signal SECTOR-ID includes logical addresses30000,30001, . . . , etc., each of the logical addresses30000,30001, . . . , etc. corresponds to one of the sectors30000,30001, . . . , etc., respectively, and a starting location of each of the logical addresses30000,30001, . . . , etc. corresponds to a pulse of the sector synchronization signal DVD_S0, respectively, as shown inFIG. 3.

Step20a:Slice the push-pull signal PP using the slicer222to generate a wobble data signal WOBDATA.

Step20b:Demodulate the wobble data signal WOBDATA using the physical address demodulating circuit224to generate a channel-bit signal CB corresponding to a physical address.

Step20c:Decode the channel-bit signal CB using the sync pattern decoding circuit226to generate a physical synchronization signal PHY_SYNC, wherein when interruption of the wobble data signal WOBDATA together with the channel-bit signal CB occurs, the sync pattern decoding circuit226continuously generates the physical synchronization signal PHY_SYNC according to a period T thereof, i.e. the period T of the previously generated physical synchronization signal PHY_SYNC shown inFIG. 3. The period T shown inFIG. 3corresponds to an Error Correction Code (ECC) block. In this embodiment, each ECC block corresponds to sixteen sectors.

Step30a:Slice the push-pull signal PP using the slicer232to generate an unfiltered wobble signal WOBBLE_woDEG.

Step30b:Filter out glitches within the unfiltered wobble signal WOBBLE_woDEG using the de-glitch unit234to generate a filtered wobble signal WOBBLE corresponding to the unfiltered wobble signal WOBBLE_woDEG.

Step30c:Generate a counter value CV according to waveforms of the filtered wobble signal WOBBLE using the counter236. The counter value CV corresponds to the rise and fall of the waveforms of the wobble signal WOBBLE.

Step40a:Generate an identification sampling signal ID_SAMPLE according to the sector identification signal SECTOR_ID using the identification sampling signal generating unit242, wherein the identification sampling signal ID_SAMPLE includes at least one simplified address3000of the logical addresses30000,30001. . . , etc., of which the least significant bits (LSB)0,1, . . . , etc. are omitted, carried within the sector identification signal SECTOR_ID. In the present embodiment, a starting location of the simplified address3000of the identification sampling signal ID_SAMPLE corresponds to a location between the logical addresses30007and30008of the sector identification signal SECTOR_ID as shown inFIG. 3.

Step40b:Generate a hybrid address signal Hybrid_Address according to the identification sampling signal ID_SAMPLE and the physical synchronization signal PHY_SYNC using the hybrid address signal generating unit244, wherein the hybrid address signal Hybrid_Address includes the simplified addresses 2FFF,3000. . . , etc. corresponding to the simplified addresses 2FFF,3000, . . . , etc. of the identification sampling signal ID_SAMPLE. In the present embodiment, starting locations of the simplified addresses 2FFF,3000. . . . , etc. of the hybrid address signal Hybrid_Address are synchronized with the physical synchronization signal PHY_SYNC as shown inFIG. 3.

Step50: Perform the target search on the optical storage disc102according to the hybrid address signal Hybrid_Address and a target address set by the MPU104using the target search module250, wherein the target search module250is capable of controlling accuracy of the target search according to the counter value CV.

Each of the simplified addresses 2FFF,3000. . . , etc. mentioned above corresponds to sixteen logical addresses. For example, the simplified address3000corresponds to the sixteen logical addresses30000,30001, . . . , and 3000F. As a result, the simplified address3000corresponds to an ECC block3000. That is, the simplified addresses 2FFF,3000. . . , etc. carried within the hybrid address signal Hybrid_Address correspond to ECC blocks 2FFF,3000. . . , etc., respectively. When the target search module250finds the target address in the hybrid address signal Hybrid_Address, the target search is completed. Furthermore, when the optical storage disc102does not store any storage information103s, the target search module250performs the target search according to the counter value CV so that the present invention method and device appropriately operate in such situation.

Please refer toFIG. 3andFIG. 4at the same time.FIG. 4is a diagram of the hybrid address signal's timing error tolerance of the sector identification signal SECTOR_ID shown inFIG. 3. The hybrid address signal Hybrid_Address is generated correctly as long as the sector identification signal SECTOR_ID has a timing error corresponding to a data length within half an ECC block. In the preferred embodiment, a starting location of the logical address30000of the sector identification signal SECTOR_ID shown inFIG. 3is aligned with a pulse of the physical synchronization signal PHY_SYNC. In this situation, the sector identification signal SECTOR_ID has no timing error. Suppose that the optical storage disc102has been written the storage information103sby an optical disc burner with poor quality so that a starting location of the logical address30003of the sector identification signal SECTOR_ID is aligned with a pulse of the physical synchronization signal PHY_SYNC as shown inFIG. 4. In this situation, the sector identification signal SECTOR_ID has a timing error of three sectors. However, in both situations shown inFIG. 3andFIG. 4respectively, the synchronization relationships between the hybrid address signal Hybrid_Address and the physical synchronization signal PHY_SYNC are the same. As long as the timing error generated during a writing process of the storage information103sdoes not exceed a length corresponding to eight sectors, the hybrid address signal Hybrid_Address will be generated correctly. As a result, the present invention method and circuit201greatly enhance the performance of the optical storage device200. According to the present invention, the optical storage device200has better tolerance of timing errors of the logical addresses carried within the readout signal due to data recording shift of the optical storage disc102in contrast to the prior art. Therefore, it is ensured that the optical storage device200accurately performs the target search according to the hybrid address signal Hybrid_Address.

In another embodiment of the present invention, a shifted target address is calculated by adding a predetermined value to the target address, and step50performs the target search on the optical storage disc102by finding the shifted target address in the hybrid address signal Hybrid_Address. Therefore, the present invention is capable of operating within the characteristic variance of the optical storage device200by adjusting the shift target address.

It is an advantage of the present invention that the present invention method and device generate the hybrid address signal according to physical addresses and logical addresses and perform the target search according to the hybrid address signal so that the present invention provides better performance in contract to the prior art. When interruption of decoding the physical addresses occurs, the present invention method and device continuously generate the second intermediate signal according to the period thereof, i.e. the period of the previously generated second intermediate signal, so that the hybrid address signal is continuously generated. Therefore, the present invention ensures that the optical storage device correctly performs the target search according to the hybrid address signal.

It is another advantage of the present invention that the hybrid address signal will be generated correctly while the sector identification signal having a timing error corresponding to a data length within half an ECC block. Therefore, the optical storage device's tolerance of the timing error ensures that the optical storage device accurately performs the target search according to the hybrid address signal.