Abstract:
A method and apparatus of controlling an optical disk apparatus determines a reference recording power at each of a plurality of recording speeds for an inserted optical disk, performs a power control procedure for a prescribed recording speed to determine a recording power at the prescribed recording speed in response to a recording request, and then computes a recording power at each of the recording speeds based on the reference recording power and the recording power determined at the prescribed recording speed. The power control procedure is performed only for an inner circumferential area of the disk, irrespective of whether a requested recording speed is less than or greater than the prescribed recording speed. As a result, the speed of the data recording operation may be substantially improved and/or other improvements may be realized.

Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    One or more embodiments described herein relate to an apparatus and method for controlling an optical disk device. 
         [0003]    2. Background 
         [0004]    Optical disk devices employ a variety of techniques to control the application of power during read and recording operations. During a recording operation, for example, an optimum power control (OPC) procedure is performed to determine the amount of power to apply based on several factors including recording speed and power calibration area (PCA)) on an inserted optical disk. 
         [0005]    These factors may be independent values or one may be dependent on the other. In the latter case, recording speed may be used as a basis for defining the power calibration area for an OPC procedure. For example, in a background art application, if a requested recording speed is faster than a predetermined speed, the OPC procedure is performed for an inner circumferential area and an outer circumferential area of the disk. Performing the OPC procedure in both of these areas increases overall recording time and represents a substantial inconvenience to the user. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: 
           [0007]      FIG. 1  is a diagram showing an optical disk device according to one embodiment; and 
           [0008]      FIG. 2  is a flow diagram showing steps included in a recording method for an optical disk device according to one embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    Optimum recording power for a specific recording speed depends on one or more factors including the type of pickup or optical disk device used, as well as changes in ambient environment and in particular changes in temperature. Irrespective of fluctuations in these features, the ratio of the change in recording power to the change in recording speed may be considered almost constant throughout low and high speeds for many applications. 
         [0010]    In recognition of this constant relationship, one or more embodiments described herein compute high-speed recording powers to be used in a middle circumferential area and an outer circumferential area of a disk. In accordance with one embodiment, these computations are made based on reference power information for each of a plurality of recording speeds and recording power values determined through an OPC procedure performed for an inner circumferential area of a disk. By performing recording operations with these computed high-speed recording power values, recording power may be adjusted more accurately through the use of recording power compensating methods such as Running OPC (ROPC), temperature compensation, and beta value compensation to name a few. 
         [0011]    Computing recording power in this manner may also reduce the length of time required to initiate a recording operation, especially when the OPC procedure is only performed in an inner circumferential area of a disk when a high-speed recording operation is requested. 
         [0012]      FIG. 1  shows an optical disk device which includes a power control apparatus according to one embodiment. This device includes a digital signal processing (DSP) recording unit  30   a , a channel bit (CB) encoder  40 , an optical drive unit  41 , an optical pickup  20 , and an R/F unit  50 . The DSP recording unit converts input digital data into a record format by adding an error correction code (ECC) to it. The channel bit encoder reconverts the data, which was converted into a record format, into a bit stream. The optical driving unit generates an optical drive input signal. The optical pickup records data onto a disk and detects data from a recording plane of a disk in accordance with the optical drive signals. And, the R/F unit normalizes the signal detected by the pickup and outputs it as binary signal. 
         [0013]    The optical disk device may further include a digital signal processing (DSP) reproducing unit  30   b , a drive unit  61 , a serve unit  60 , a microprocessor  70 , and a memory  71 . The DSP reproducing unit restores a binary signal received from the R/F unit into original data in accordance with a clock which is phase-synchronized to the binary signal. The drive unit drives a spindle motor M to rotate an optical disk  10  relative to motion of the pickup  20 . The servo unit controls the drive of the drive unit based on a tracking error (TE) signal and a focus error (FE) signal of the pickup and a rotational speed of the optical disk. 
         [0014]    The memory stores reference recording power values for each of a plurality of disk manufacturers (disk codes) for each of a plurality of recording speeds. The memory also stores a recording power ratio between the recording speeds. Memory  71  is preferably a nonvolatile memory (for example, EEPROM), although another type of memory may be used. 
         [0015]    The microprocessor  70  detects a power ratio based on the reference recording power at each recording speed stored in the memory, and also detects a desired (e.g., optimum) recording power at each recording speed based on the detected power ratio and the detected optimum recording power. The latter power (i.e., the detected optimum recording power) may be determined through an OPC procedure performed for an inner circumferential area of the optical disk. A recording operation is then performed by applying the desired (e.g., optimum) recording power at each detected recording speed. 
         [0016]      FIG. 2  is a flow diagram showing steps included in a recording method in accordance with one embodiment. For illustrative purposes, the method will be described with reference to the device shown in  FIG. 1 . However, those skilled in the art can appreciate that the method may be performed using a different disk device. 
         [0017]    In describing the method, it is to be recalled that memory  71  preferably stores the reference recording power for each of a plurality of manufacturing companies relative to each of a plurality of recording speeds. The memory may also store one or more beta (β) values computed through simulation during the process of manufacturing the optical disk device. The beta values may be stored in the form of a table in association with corresponding disk manufacturers (disk codes). 
         [0018]    Referring to  FIG. 2 , when a disk  10  is inserted into the optical disk device (S 10 ), microprocessor  70  ascertains the disk manufacturing company of the disk through a disk code read from the inserted optical disk (S 11 ). The microprocessor then reads from memory the reference recording power at each recording speed for the ascertained disk manufacturing company (S 12 ), and computes recording power ratios for the speeds based on a predetermined (e.g., 4×) recording speed. These ratios are then stored in the memory (S 13 ). 
         [0019]    As an example of determining the power ratio, if the reference recording power stored in the memory for the disk code of the optical disk is 10 mW at 4× recording speed, 15 mW at 6× recording speed, 18 mw at 8× recording speed, and 20 mW at 10× recording speed, then the power ratio in other recording speeds is 1.5 at 6× recording speed, 1.8 at 8× recording speed, and 2 at 10× recording speed, on the basis of the recording power in 4× recording speed, i.e., 10 mW. These power ratios are preferably stored in table form in memory  71 . 
         [0020]    Hereafter, if the recording operation is requested from the user (S 20 ), the microprocessor performs an OPC procedure on the optical disk. According to this procedure, if the recording speed requested is faster than a prescribed (e.g., 4×) recording speed (S 30 ), the microprocessor performs the OPC procedure to detect a predetermined (e.g., optimum) recording power at the prescribed (e.g., 4×) recording speed. Information indicative of this power is then stored in memory (S 31 ). 
         [0021]    Even though the recording speed requested is faster than 4× recording speed, the OPC procedure is not performed for both in the inner circumferential area and the outer circumferential area of the disk. Instead, according to the present embodiment, the OPC procedure is performed only in the inner circumferential area of the disk in order to reduce the length of time of the OPC procedure. This is in contrast to the way in which background art methods apply an OPC procedure under these circumstances. 
         [0022]    More specifically, according to background-art methods, an OPC procedure is performed for both the inner and outer circumferential areas of a disk. Performing the OPC procedure in both of these areas introduces a significant delay into the recording process which, for example, may be more than approximately 10 seconds. Moreover, OPC procedures may not perform accurately in the outer circumferential area. Consequently, background-art methods are susceptible to errors which may cause a failure in the OPC procedure and thus the overall recording process. 
         [0023]    At least one embodiment may be implemented to overcome these problems. According to one embodiment, in performing an OPC procedure microprocessor  70  may read out the disk code of an inserted optical disk  10  (for example, DVD-R) and the reference recording power corresponding to a predetermined recording speed (for example, 4× recording speed) from the memory, and applies to the optical driving unit  41  an adjusting signal which changes the recording power by a prescribed magnitude (ΔP) based on the read-out recording power. The prescribed magnitude may be pre-stored in the optical disk device or in the storage area of the disk, another medium, or device. 
         [0024]    As an example, if the read-out reference recording power is 10 mW and the amount of power change (ΔP) is 1 mW, microprocessor  70  applies to the optical driving unit  41  an adjusting signal which makes, for example, 7-step increments (+ΔP) of 1 mW and 7-step decrements (−ΔP) of 1 mW based on a read-out recording power (10 mW). In response, the optical driving unit  41  outputs a driving signal for test data as power corresponding to the applied adjusting signal, and the optical pickup  20  records the test data into a prescribed test region of the optical disk  10 , e.g., a test region within a power calibration area (PCA). 
         [0025]    Once recordation of the test data is completed, the microprocessor  70  consecutively reads out the test data which is recorded and detects the beta (β) value from the reproducing RF signal. The beta value indicates a degree of asymmetry of the reproducing RF signal. 
         [0026]    After the beta value has been detected, the microprocessor  71  obtains a function from the detected beta value and each recording power corresponding to it. The function is then compared with the beta value stored in memory  71  corresponding to the disk code of the optical disk and the OPC recording speed. The optimum recording power at the recording speed (4× recording speed) is then determined based on this comparison and stored into the memory. 
         [0027]    After the power ratio at each recording speed for the inserted optical disk and the optimum recording power at 4× recording speed through the OPC procedure are determined, the microprocessor preferably determines the optimum recording power at one or more recording speeds other than 4× recording speed, which is the speed of performing the OPC procedure. In performing this function, the microprocessor multiplies the optimum recording power (for example, 9 mW) at 4× recording speed detected through the OPC by the power ratio stored for other speeds (×6, ×8, ×10, . . . ) respectively so as to detect the optimum recording power at other speeds. 
         [0028]    Therefore, in the exemplary case considered above, the optimum recording power at 6× recording speed is determined as follows: 9 mW (optimum recording power at 4× recording speed)×1.5 (power ratio for 6× recording speed)=13.5 mw. The optimum recording power at 8× recording speed is determined as follows: 9 mW (optimum recording power at 4× recording speed)×1.8 (power ratio for 8× recording speed)=16.2 mw. The optimum recording power at the 10× recording speed is determined as follows: 9 mW (optimum recording power at 4× recording speed)×2 (power ratio for 10× recording speed)=18 mw. The microprocessor stores the optimum recording powers at these other recording speeds in memory  71  (S 32 ). 
         [0029]    Next, the microprocessor performs a requested recording operation by applying the optimum recording power at one of the recording speeds stored in the memory (S 34 ). The microprocessor can compensate the optimum recording power through an ROPC procedure, which adjusts the strength of a laser beam based on the beta value derived from the reproducing RF signal of the data which is recorded during the recording operation (S 35 ). The microprocessor reads out the recorded data, stopping the recording operation for a certain time at a prescribed time interval or at a given distance or position relative to the inner or outer circumference of the disk during the recording operation. The microprocessor also detects the beta value for the reproducing signal. The recording operation and recording power compensating operation will continue in this manner until all of the requested data is recorded onto the disk (S 40 ). 
         [0030]    If the requested recording speed is slower than the prescribed recording speed (e.g., the 4× recording speed in the above embodiment (S 30 )), the microprocessor performs the OPC procedure for the requested recording speed in the inner circumferential area of the optical disk  10 . The optimum recording power is then determined and stored in the memory (S 33 ). The microprocessor also performs the requested recording operation by applying the optimum recording power for the requested recording speed which is stored in the memory. 
         [0031]    If the recording power table for the inserted optical disk does not exist in the memory, the microprocessor may use the recording power for each recording speed stored as a default in the memory, or an averaged recording power of each recording speed for other optical disks made by other manufactures. 
         [0032]    Meanwhile, if the optical disk is recorded at constant angular velocity (CAV), the recording speed increases linearly as the recording operation proceeds from the inner circumferential area to the outer circumferential area of the disk. In this case, the recording power must be increased commensurately based on an increase in the recording speed. 
         [0033]    In the case where the optical disk is rotated at constant linear velocity for each zone (Zone CLV), the recording speed is increased step-by-step in each bounded zone and subsequently the recording power may be increased step-by-step. The optical disk may be considered to rotate at constant linear velocity for each zone when the linear velocity is kept constant within each zone and the linear velocity is allowed to increase in a next zone, provided that the data area from the inner circumference to the outer circumference is divided into the prescribed number of zones. 
         [0034]    In the Zone CLV mode, each zone may be divided uniformly and may also be divided arbitrarily. Further, the number of zones may be randomly determined and an increment of the recording speed may be determined uniformly or arbitrarily. 
         [0035]    According to one embodiment, in the case where recording is performed while rotating the disk in the Zone CLV mode, the boundary of the zone to which the recording power of next step is applied may be changed by detecting jitter and beta values of the recorded data. 
         [0036]    For example, in the case where the disk is widely divided into inner and outer circumferential areas to allow the Zone CLV mode to be applied, the boundary of the inner circumference and the outer circumference is generally an address of 80,000. If jitter and beta values measured during recording the inner circumference are at some acceptable level, it is possible to apply the recording speed and recording power used in the outer circumference from an address of 60,000, which is located closer than the address of 80,000 corresponding to the boundary of the inner and outer circumferential areas. 
         [0037]    Meanwhile, if the jitter and beta values measured during recording at the inner circumference are not at acceptable levels, it is possible to apply the recording speed and recording power used in the outer circumference from an address of 100,000, which is located further out than the address of 80,000 corresponding to the boundary between the inner and outer circumferential areas. 
         [0038]    In accordance with an alternative embodiment, the reference recording power at each of the recording speeds may be determined by averaging read-out reference powers at each of a plurality of recording speeds according to other optical power tables. The averaged values may then be placed in a table stored in memory and used when, for example, an optical power table was not previously stored in the optical disk device corresponding to the manufacturer (e.g., disk code) of an inserted disk. These other optical power tables may, for example, correspond to ones of other disk manufacturers. 
         [0039]    In accordance with another embodiment, an optical disk apparatus comprises ascertaining a reference recording power at each recording speed for an inserted optical disk; performing an OPC procedure for a prescribed recording speed to detect the recording power at the prescribed recording speed if the record is requested; computing a recording power at each recording speed as a basis of the ascertained reference recording power and the detected recording power at the prescribed recording speed. 
         [0040]    Preferably, the ascertaining comprises ascertaining a manufacturing company of the inserted optical disk; and reading out a reference recording power at each recording speed of the ascertained manufacturing company, which is stored in the optical disk apparatus. 
         [0041]    At this time, the manufacturing company of the optical disk is ascertained through a disk code of the inserted optical disk, and the reference recording power at each recording speed is stored in a memory of the optical disk in a form of table in association with the manufacturing company of the disk. 
         [0042]    Further, the ascertaining comprises reading-out a default value of a reference recording power at each recording speed stored in the optical disk apparatus, or reading-out and averaging the reference powers at each recording speed for other manufacturing companies stored in the optical disk apparatus, if the information on the ascertained manufacturing company is not stored in the optical disk apparatus. 
         [0043]    Further, the ascertaining further comprises obtaining and storing a power ratio of the reference recording power at other recording speeds on a basis of the prescribed recording speed based on the read-out reference recording power at each recording speed; and the recording power at each recording speed is computed by multiplying the stored power ratio by the detected recording power at the prescribed recording speed. The detecting and the computing are performed if a recording speed faster than the requested prescribed recording speed. 
         [0044]    The embodiment further comprises performing recording operation by applying the computed recording power at each recording speed, and may further comprise compensating the recording power on a basis of a reproducing signal for data which is recorded. At this time, the compensating is performed on a basis of an asymmetry degree of a reproducing signal for the recorded data. 
         [0045]    Further, the performing the recording operation further comprises changing a boundary of a zone to which a recording power of a next step is applied based on a reproducing signal for recorded data if a Zone CLV mode is used, and whether or not to change the boundary of the zone is determined based on an asymmetry degree and a jitter value of the reproducing signal for the recorded data. 
         [0046]    According to one or more embodiments described herein, it is possible to initiate the record operation more rapidly by reducing the length of time which it takes to perform the OPC procedure and prevent an OPC fail in the outer circumference, since the OPC procedure is performed only in the inner circumference even in a case of high-speed recording being requested. Further, it is possible to improve recording quality and reduce the length of recording time by adjusting the recording speed and the recording power in accordance with the recording state. 
         [0047]    Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
         [0048]    Although embodiments of the present invention have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention. More particularly, reasonable variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the foregoing disclosure, the drawings and the appended claims without departing from the spirit of the invention. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.