Patent Application
20050099912
1. Field of the Invention
The present invention relates in general to a method for writing data to an optical disc, and in particular to a method using different data writing strategies according to the rotation speed of the disc drive.
2. Description of the Related Art
CDRW (ReWritable) drivers are designed to record data, video and other content from PC and other platforms. CDRW main factures recognize that content must be portable across various platforms.
The recording layer of a blank CDRW disc is polycrystalline, which is a phase-change material. During writing, a focused laser beam selectively heats partial areas of the phase-change material to be above the melting temperature of 500-700° C., so all the atoms in this area can move rapidly in the liquid state causing by the high temperature. When cooled with sufficiently quickly, the random liquid state is ‘frozen-in’ and the so-called amorphous state is obtained. If the phase-change layer is heated to below the melting temperature but above the crystallization temperature (200° C.) for a sufficient time (at least longer than the minimum crystallization time), the atoms revert back to an ordered state, i.e. the crystalline state.
The amorphous and crystalline states have different refractive indexes, and can therefore be optically distinguished. For a CDRW disc, the amorphous state has a lower reflectivity than in the crystalline state and, during read-out, this produces a signal identical to that of a regular dual layer CDRW disc, making it possible to read CDRW discs with CD-ROM drives and CD Video players.
The phase-change medium can be rewritten in a single pass of the focused laser beam. In the CDRW system, the data is recorded on discs by means of a write strategy, using different laser output levels. This strategy has two parts, a pulsed part (pulsing is necessary to write amorphous ‘marks’), and a non-pulsed part, in which the strategy writes crystalline areas between the marks.
The write strategy is determined according to the type of optical disc, and the CDRW drive, and the recording speed.
Different write strategies are implemented according to different predetermined ranges of optical data recording speed. For example, a first write strategy is used for recording data speed under 16X. Here, the pulse width of the first write strategy is adjustable to meet different data recording speeds under 16X. While the data recording speed exceeds 16X, the first write strategy does not conform to the data recording speed by adjusting the pulse width of the same write strategy. Thus, the recorded mark fails. Therefore, another write strategy is employed record data at a speed exceeding 16X.
The data recording speed of CDRW drive, however, may be determined according to the quality of the optical disc or performance of the host computer. In addition, in CAV (constant angular velocity) mode, the data recording speed is altered according to different recording radius of the optical disc. Moreover, the new data recording speed may correspond to a different write strategy. Thus, the conventional optical data recording method limits the recording speed to prevent the problems mentioned above.
The present invention provides a method of recording optical data. During data recording, the write strategy is dynamically switched or adjusted according to the practical (even instant) rotation speed of the disk drive. For example, the low-speed write strategy is switched to high-speed write strategy when the rotation speed of the disk drive is increased, the high-speed write strategy is switched to low-speed write strategy when the rotation speed of the disk drive is decreased, and the power waveform of the write strategy accordingly, thus improving optical data recording quality under different disk drive rotation speeds.
To achieve the above-mentioned contents, the present invention provides also an optical data recording method for a disk drive having a plurality of rotation speeds. First, a plurality of write strategies corresponding to different rotation speeds of the disk drive is provided. Next, the rotation speed of the disk drive is detected. The write strategy is then selected according to the rotation speed of the disk drive. Therefore, optical data is written to an optical disc with the selected write strategy. Finally, the rotation speed of the disk drive is continuously detected during optical data writing, and optical data is written to the optical disc with another write strategy when the rotation speed of the disk drive is changed and corresponds to another write strategy.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings, given by way of illustration only and thus not intended to be limitative of the present invention.
As mentioned above, different predetermined ranges of optical data recording speed require different write strategies. For example, a first write strategy is employed to recording data at a speed under 16X. Here, the pulse width of the first write strategy is adjustable to meet different data recording speeds under 16X. When the data recording speed exceeds 16X, the first write strategy can not conform to the data recording speed by adjusting the pulse width. Thus, the size of the generated mark is too large, causing data recording failure. Therefore, another write strategy is defined to record data at a speed exceeding 16X.
The present invention provides an optical data recording method, in which write strategies are dynamically switched during data recording by firmware.
Next, one of the write strategies stored in a first memory device are selected according to the detected rotation speed of the disk drive (S2). The write strategy is determined at least according to the type of optical disc, the disk drive, and the performance of the host computer. The related parameters of the write strategy are stored in a second memory device or the first memory device, comprising the recording power change time and the recording power sustain time for writing data to the optical disc.
Next, the waveform of the write strategy is generated according to the parameters read from the memory device (S3). Thus, data is written to the optical disc according to the selected write strategy. In addition, the parameters of the write strategy can be dynamically adjusted. Thus, the host computer determines if the write strategy requires adjustment (S4). Here, the write strategy is determined according to the hardware setting of the system. If yes, the disk drive generates appropriate write strategy parameters according to the practical rotation speed of the disk drive, and writes the parameters to the memory device (S5). Here, the memory device can be the same memory device used in Step S3 or another memory device. Next, the disk drive outputs a high voltage signal WSTPOK, which represent completion of the write strategy parameter adjustment (S6). After the disk drive outputs the high voltage signal WSTPOK, the host computer transforms the signal WSTPOK to low voltage level at an appropriate time, and outputs the low voltage signal WSTPOK to the disk drive (S7). It is noted that the parameters of the write strategy usually are not changed prior to the drop in voltage level from high to low of the WSTPOK signal. The disk drive reads the adjusted write strategy parameters set in Step S6 when receiving the low voltage WSTPOK signal (S8). Thus, the adjustment of the write strategy parameters is complete. If the disk drive does not receive the low voltage WSTPOK signal, the write strategy parameters performing is not changed. Finally, data is recorded to the optical disc employing the adjusted write strategy (S9).
If at Step S4, the write strategy does not require adjustment, the process skips to Step S8 directly. After recording data to the optical disc (S9), the disk drive determines if the data recording process has finished or not (S10). If not, the process returns to Step S1 to detect the rotation speed of the disk drive. If yes, the detection of the disk drive rotation speed halts. Thus, the optical data recording method according to the embodiment of the present invention is complete.
According to the embodiment of the present invention, the practical rotation speed of the disk drive is continuously detected in real-time during when data is recording. In addition, the write strategy is selected according to the detected rotation speed of the disk drive. Thus, the write strategy for recording data is adjusted or changed to meet the present rotation speed of the disk drive. Therefore, the quality of optical data recording is improved.
In addition, there are many methods of accomplishing dynamic switching or adjustment of the write strategy by application, software, or firmware. For example, the rotation speed of the disk drive is continuously detected by firmware. The high-speed write strategy is written to the memory device by firmware and a signal (WSTPOK) is output to hardware when the rotation speed of the disk drive exceeds a predetermined threshold value. The hardware usually does not switch the write strategy immediately while receiving the signal (WSTPOK), rather, the hardware will switch to perform another write strategy and clear the signal (WSTPOK) after waiting for a predetermined length of mark (or space), and the predetermined length of space (or mark). As shown in
Here, the voltage level of the signal (WSTPOK) set to ‘1’ is output by firmware. Next, firmware continuously detects the voltage level of the signal (WSTPOK). The hardware has switched the write strategy when the voltage level of the signal (WSTPOK) becomes ‘0’. In addition, the purpose of the hardware waiting for a predetermined time length is to prevent simultaneous use of different write strategies to record data at the same time, which causes recording failure.
Accordingly, the present invention provides an optical data recording method for dynamically switching or changing write strategies by firmware programming or other equivalent ways to adjust recording parameters stored in the memory device, thus improving recording quality under changing disk drive rotation speeds.
The embodiment of the present invention uses CD recorders and CDRW discs as an example, however, the present invention may also be implemented with DVD recorders and DVDRW discs, and are not limited by what kind of disc and recorder is used.
The foregoing description of the invention has been presented for purposes of illustration and description. Obvious modifications or variations are possible in light of the above teaching. The embodiments were chosen and described to provide the best illustration of the principles of this invention and its practical application to thereby enable those skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.
| Number | Date | Country | Kind |
|---|---|---|---|
| 92131365 | Nov 2003 | TW | national |
