The invention relates to writing quality control for an optical storage medium, and more particularly, to apparatuses and related methods for controlling the writing quality of the optical storage medium during optical recording.
When writing data onto an optical storage medium (e.g. optical disc), an optimum power calibration (OPC) is performed on a specific area called power calibration area (PCA) of the optical storage medium to acquire a preferred write power utilized for data recording. The specific area is usually located at an inner most track of the optical storage medium and the write power determined by the OPC process performed on the inner most track may not be applicable to data recording onto an outer track. Since write power is crucial to the writing quality of an optical storage medium, an unsuitable write power may render written data on the optical storage medium unable to be read back correctly. To solve this problem, in addition to calibrate the write power at an inner track, a conventional method performs the OPC process on an outer track, too. A write power for any track located between the inner track and the outer track may be determined by interpolation. However, a characteristic of the optical storage medium between the inner and outer tracks of the optical storage medium may not change linearly, causing this conventional interpolation method fail to accurately predict a preferred write power. The write power determined by the OPC process is insufficient for data recording everywhere on the optical disc due to numerous of factors such as tilt drift, temperature variation, and unevenness of the dye.
Some other conventional methods utilize dynamically compensation process such as a running optimum power control (ROPC) procedure to dynamically adjust write power to overcome the above-mentioned problem. A ROPC method monitors a characteristic of a writing radio frequency (WRF) signal used to write data onto an optical storage medium, and dynamically compensates laser power by comparing the current monitored value with a target characteristic value. Nevertheless, a signal-to-noise ratio (SNR) is usually poor as this method utilizes the WRF signal as a reference for power calibration.
In U.S. Pat. No. 6,636,468, another dynamic write power control method is provided. In this method, some stopping points are set during a write procedure, and at each stopping point, data previously written during the write procedure is read. According to the read-back data, a write power is adjusted and the write procedure is restarted using the adjusted write power. However, adjusting a write power to control writing quality of an optical storage medium causes a radio frequency (RF) amplitude level to vary during a write procedure, and the amount of the write power capable of being controlled is limited due to a physical limit of a laser diode used to record data onto the optical storage medium. All of these factors degrade the writing quality.
Apparatuses and related methods of controlling a writing quality for optical recording by adapting the recording tangential velocity are provided.
Some embodiments of an apparatus for controlling writing quality of an optical storage system are provided. The optical storage system has an accessing logic for steering data to be written onto or read from an optical storage medium. The apparatus comprises a halting controller, an evaluation device, a recording tangential velocity (RTV) adjusting device, and a starting controller. The halting controller, coupled to the accessing logic, requests the accessing logic to halt a write procedure at a stopping point. The evaluation device, coupled to the accessing logic, requests the accessing logic to read at least a portion of data recorded onto the optical storage medium and evaluates the writing quality while reading the portion of the data to generate an evaluation result. The RTV adjusting device, coupled to the evaluation device and the accessing logic, requests the accessing logic to adjust the RTV of the optical storage medium if the evaluation result does not satisfy predetermined criteria. Finally, the starting controller, coupled to the accessing logic, requests the accessing logic to restart the write procedure to continue writing data onto the optical storage medium.
In addition, some embodiments of a writing quality controlling method comprises halting a write procedure at a stopping point, reading at least a portion of a data recorded onto the optical storage medium in the write procedure, evaluating the writing quality of the portion of the data to generate an evaluation result, adjusting the recording tangential velocity (RTV) of the optical storage medium if the evaluation result does not satisfy predetermined criteria, and restarting the write procedure to continue writing data onto the optical storage medium.
Embodiments of an apparatus for controlling the writing quality of an optical storage system are also provided. The optical storage system contains an accessing logic for steering data to be written onto or read from an optical storage medium. Some embodiments of the apparatus comprise an evaluation device, and a recording tangential velocity (RTV) adjusting device. The evaluation device, coupled to the accessing logic, evaluating the writing quality by detecting at least a characteristic parameter during a write procedure to generate an evaluation result. The RTV adjusting device, coupled to the evaluation device and the accessing logic, requests the accessing logic to adjust the RTV of the optical storage medium if the characteristic parameter does not satisfy predetermined criteria.
Furthermore, some embodiments of a method for controlling the writing quality of an optical storage system comprise evaluating the writing quality by detecting at least a characteristic parameter during a write procedure to generate an evaluation result, and adjusting the RTV of the optical storage medium if the characteristic parameter does not satisfy predetermined criteria.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
The evaluation signal Seva is fed into the RTV adjusting device 165. Then the RTV adjusting device 165 checks whether an evaluation result represented by the values transmitted via the evaluation signal Seva satisfies any of the predetermined criteria. If it is satisfied, the RTV adjusting device 165 will not adjust the RTV of the optical disc 105, and the accessing logic 115 restarts the currently halted write procedure when receiving a starting signal SS outputted from the starting controller 170. On the other hand, if the evaluation result fails to satisfy the predetermined criteria, the RTV adjusting device 165 will generate an RTV adjusting signal SRTV and deliver it to the accessing logic 115. In this embodiment, the well-known servo control mechanism is implemented in the accessing logic 115. Therefore, as the accessing logic 115 receives the RTV adjusting signal SRTV, the servo control mechanism controls the rotation speed of the optical disc 105, resulting in an adjustment to the RTV. In some embodiments, values transmitted by the RTV adjusting signal SRTV are determined via utilizing a look-up table. However, the utilization of the look-up table is only an example for implementing the RTV adjusting device 165 and is not meant to be taken as a limitation of the present invention. For example, in other embodiments, the RTV adjusting device 165 can also determine the RTV adjusting signal SRTV by utilizing linear/non-linear transform, fuzzy logic, or other artificial intelligence algorithms. Please note that the RTV of the accessing logic 115 is utilized to compensate one or a combination of defects in the coating of the optical storage medium 105, variation in ambient temperature, variation in track radius, variation in laser power level, tilt, and defocus.
As shown in
Step 210: The optical storage system 100 starts a write procedure.
Step 215: An RTV for the write procedure is set according to a predetermined recording speed.
Step 220: Perform an OPC calibration.
Step 225: A write strategy and a write power of the write procedure is determined according to results from the OPC calibration
Step 230: Start to record data onto the optical disc 105 according to the RTV, the write strategy and the write power.
Step 235: Check if the data to be recorded is entirely recorded onto the optical disc 105. If yes, go to Step 275; otherwise, go to Step 240.
Step 240: Has the trigger 152 indicated the writing quality should be reevaluated? If yes, go to Step 245; otherwise, go to Step 235.
Step 245: Halt the write procedure at the stopping point.
Step 250: Read at least a part of the recorded data from the optical disc 105 and perform an evaluation operation.
Step 255: Does a result of the evaluation operation indicate that the RTV requires adjustment? If yes, go to Step 260; otherwise, go to Step 270.
Step 260: Is an adjusting amount of the RTV greater than a threshold? If yes, go to Step 220; otherwise, go to Step 265.
Step 265: Adjust the RTV according to the evaluation result.
Step 270: Restart the write procedure utilizing the original write strategy, the original write power and the original RTV, and then go back to Step 235.
Step 271: Restart the write procedure utilizing the original write strategy, the original write power and the updated RTV, and then go back to Step 235.
Step 275: End the write procedure.
The RTV adjusting signal SRTV′ is further fed into the resetter 380. The resetter 380 examines if an adjusting amount of the RTV reaches a threshold value (e.g., 20%). If the adjusting amount of the RTV does not reach the threshold value, the resetter 380 ignores the RTV adjusting signal SRTV′ and the accessing logic 315 adjusts the RTV according to the RTV adjusting signal SRTV′. However, if the adjusting amount of the RTV reaches or exceeds the threshold value, the resetter 380 generates a reset signal Sreset′ to request the accessing logic 315 to update the write strategy and the write power. That is, when the RTV currently in use requires a significant amount of adjustment, it means many other parameters may also need to be adjusted in addition to the write power. In one embodiment of the accessing logic 315, when receiving the reset signal Sreset′, the accessing logic 315 halts the write procedure temporarily and then performs the OPC calibration again to update the write strategy and the write power. After the write strategy and the write power are updated, the write procedure is restarted.
Step 410: The optical storage system 300 starts a write procedure.
Step 415: An RTV for the write procedure is set according to a predetermined write speed.
Step 420: Perform an OPC calibration.
Step 425: A write strategy and a write power of the write procedure is determined according to results from the OPC calibration
Step 430: Start to record data onto the optical disc 305 utilizing the RTV, the write power, and the write strategy.
Step 435: Check if the data to be recorded is entirely recorded onto the optical disc 305. If yes, go to Step 465; otherwise, go to Step 440.
Step 440: Is an evaluation operation being triggered? If yes, go to Step 445; otherwise, go to Step 430.
Step 445: Perform the ROPC operation by evaluating the WRF signal during data recording, and generate at least a characteristic parameter transmitted by an evaluation signal Seva′ representing writing quality of the currently running write procedure.
Step 450: Check if RTV adjustment is required by examining the characteristic parameter. If the RTV adjustment is required, go to Step 455; otherwise, go to Step 430.
Step 455: Is an adjusting amount of the RTV greater than a threshold? If yes, go to Step 420; otherwise, go to Step 460.
Step 460: Adjust the RTV utilized by the currently in use write procedure according to the characteristic parameter, and then go back to Step 435.
Step 465: End the write procedure.
The present invention provides a mechanism for controlling writing quality when writing data onto an optical storage medium of an optical storage system. Specifically, an RTV adopted by the optical storage system, instead of a write power of the optical storage system, is adapted in order to compensate various changes and thus improve the writing quality. By adapting the RTV, some physical properties of writing the optical storage medium, such as maintaining a constant RF level, is better than the conventional means of changing the write power. Additionally, there is a physical limit imposed on the laser diode which restricts the maximum write power be used for data recording. However, it is not a concern to the writing quality control mechanism that improves the writing quality by changing the RTV of the optical storage medium.
Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, consumer electronic equipment manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Also, the term “couple” or “couples” is intended to mean either an indirect or direct electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.