KR100964508B1 - Driving method of optical drive and apparatus adopting the method - Google Patents

Abstract

The present disclosure relates to an optical drive and a driving method thereof. The driving method compensates for the aberration of the objective lens due to thermal deformation by accommodating the temperature detection of the objective lens and the control of the optical component position according to the information processing procedure such as initialization process, information reading or writing during media loading. do. Such aberration compensation enables high quality information processing.

Description

Optical drive and its driving method {Driving method of optical drive and apparatus adopting the method}

The present invention relates to an optical drive and a driving method thereof, and to an optical drive and a driving method thereof capable of compensating for changes in optical characteristics of an optical lens due to thermal deformation.

The optical drive has a structure for optically recording information to and reading information from a rotating medium. In this structure, the objective lens facing the rotating medium is an important factor in determining the quality of the information recording and reproducing. Recently, objective lenses made of plastic rather than glass have been used, which leads to a change in optical properties due to thermal deformation in addition to an inexpensive material cost.

Thermal deformation of the objective lens is much larger with the use of a high power laser. Thermal deformation of the objective lens results in a change in curvature, resulting in spherical aberration. Such aberrations inevitably result in signal distortion. According to the signal distortion, servo signal levels such as focus error and tracking error are lowered, and as a result, disc misrecognition, automatic adjustment malfunction, read failure, and the like may occur, and jitter is difficult to avoid.

According to an embodiment of the present invention, an optical drive and a driving method thereof capable of effectively compensating spherical aberration caused by thermal deformation of an objective lens are provided.

Therefore, an optical drive and a spherical drive method are provided that can effectively suppress servo signals and jitter deterioration even when an objective lens made of a material weak against heat is used.

According to one embodiment,

Light source;

An objective lens provided on an optical path between the light source and the optical medium to face the optical medium;

A collimator provided between the objective lens and the light source to control light incident on the objective lens;

A collimator actuator for adjusting the optical distance of the collimator to the objective lens; And

And a controller for controlling the collimator actuator to detect the temperature of the objective lens and correct the optical distance according to the position correction value of the collimator corresponding thereto.

The control unit is provided with an optical medium drive device, characterized in that for detecting the medium after the optical distance is corrected in the initialization step of loading the medium.

According to a specific embodiment, the control unit may further include correcting the optical distance in the information processing step for the medium. Correction of the optical distance in the information processing step is performed in an open-loop routine called by periodic interruption in the information processing routine.

According to another specific embodiment, the control unit may further include compensating for the optical distance in the step of entering the operating state from the non-operation state in the state where the medium is loaded.

One way to drive an optical drive is to:

Detecting media loading to the optical drive;

A first correction step of measuring the temperature of the objective lens facing the medium, correcting the position of the collimator by calculating a position correction value of the collimator from the measured temperature after the medium is loaded;

Irradiating light onto the medium through the collimator and the objective lens and determining the type of the medium from the reflected optical signal; And

And performing an information processing process on the medium associated with information recording or reading corresponding to the medium type.

According to another embodiment of the present invention, an optical drive driving method includes periodically measuring a temperature of an objective lens and calculating a correction value from a reference position of the collimator based on a temperature measured for each period during the information processing. And a second correcting step of periodically correcting the position.

Optical drive driving method according to another embodiment:

Waiting for the return to the information processing step while the information processing on the medium is stopped;

A third correction step of correcting the position of the collimator by measuring a temperature of the objective lens and calculating a position correction value of the collimator from the measured temperature when returning from the waiting step to the information processing step; do.

The objective lens compensates by the collimator when spherical aberration occurs due to thermal deformation. The position compensation of the collimator precedes the focusing of the objective lens when the medium is loaded, and is periodically performed in the information processing process including the process of writing / reading information about the medium. In addition, the position compensation of the collimator is preceded when moving out of the rest state where no information processing is performed. This complex collimator position compensation successfully compensates for spherical aberration of the objective lens throughout the optical drive operation. By this compensation, the unstable operation of the optical drive due to the deterioration of the servo control signal due to the spherical aberration is suppressed, thereby realizing optimal readability.

Hereinafter, exemplary embodiments of a method of driving an optical drive according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing the structure of a basic optical drive. Referring to FIG. 1, an optical drive according to an embodiment of the present invention includes an objective lens 120 that focuses a light source 190 and light therefrom onto an information recording surface of a disc-shaped medium 110. It is provided. Behind the objective lens 120, a collimator 140 for collimating the divergent light from the light source 190 is provided. Between the collimator 140 and the light source, the reflected light from the disk is reflected to the photodetector 170, and a part of the light from the light source 190 is reflected to the detector 180 for light output monitor, the majority of which is the medium 110. A beam splitter 160 is transmitted to the side.

As shown in FIG. 1, the collimator 140 is provided with an actuator 150. Unlike the actuator (not shown) for the objective lens 120, the actuator 150 generally has a linear reciprocating structure by a step motor, and thus, the distance of the collimator 140 with respect to the objective lens 120 is adjusted. In accordance with the distance adjustment, the incident angle change of the beam flux to the objective lens 120 is displayed by the collimator 140, so that spherical aberration of the objective lens 120 is compensated. As the objective lens 120 is deformed by heat, spherical aberration may occur, and the objective lens 120 becomes more severe toward the peripheral portion of the lens. Such deformation of the objective lens 120 is affected by the material, for example, plastic, compared to glass, causes a large deformation of the objective lens 120 due to thermal changes. The spherical aberration according to the deformation of the objective lens 120 is compensated by the position correction of the collimator 140. For this compensation, a temperature sensor 130 is provided at one side of the objective lens 120, and the temperature sensor 130 is connected to the controller 135. The controller 135 determines the compensation position of the collimator 140 according to the detected temperature, and the data is called from the lookup table inside the controller 135 obtained by trial and error.

The first, second and third compensation steps mentioned in the following description of the embodiment are all related to the position correction of the collimator 140 according to the measurement temperature of the objective lens 120.

As shown in FIG. 2, the first compensation step 23 is preferentially performed in a servo startup routine including an initialization process after media loading. That is, the initialization process (or servo startup, 21) is performed along with the media loading. First, the first compensation steps (COMPENSATION 1, 23) are performed, and then the disc detection step 24 is performed. The first compensating step 23 first detects the temperature of the objective lens 120 (23a), from which the correction or compensation distance of the collimator 140 necessary to compensate for the spherical aberration of the objective lens 120 Calculating 23b and compensating the position of the collimator 140 according to the calculated correction distance 23c. As described above, the spherical aberration caused by the objective lens 120 is compensated for by correcting the position of the collimator 140. After the first compensation step 23, the initialization of the mechanism for detecting the type of the general loaded medium and the like and setting up the read / write for the detected medium is possible. As described above, by performing a process such as detecting a medium type requiring focusing of the objective lens 120 after the first compensation step 23, the degradation of the servo signal due to spherical aberration is suppressed, thereby detecting the disc (type) step 24. Reduce failures).

As shown in FIG. 3, when the main routine 30 is started and the read or write is determined (31), the process proceeds to the information processing 32. The second compensation step (COMPENSATION 2, 32b) is performed in the information processing process 32 associated with the reading or writing of the information on the medium. If a read or write operation command is given, it subsequently transitions to reading or writing step 32a of the given information, at which time the subroutine called by a periodic interrupt in the microprocessor that the read or write routine (step 32a) executes. As a result, a second compensation step 32b is executed. The second compensation step, which is a subroutine, is an open loop method without feedback, which sequentially performs temperature detection-position correction and then returns to the read or write step 32a. Accordingly, the second compensation step 32b by the subroutine called by the interrupt is periodically repeated in the information processing process including the information read / write process.

As shown in FIG. 3, the third compensation step may be performed in a sleep mode or a standby mode waiting for a restart or wake-up as the main routine ends or pauses while the medium is loaded. Then it is executed 40. When restart or wake-up is determined 41 by an external command or the like in the standby or sleep mode, the process proceeds to the third compensation step (COMPENSATION steps 3 and 42). The third compensation step 42 is performed after waking up in the standby mode and before returning to the main routine, thereby measuring the temperature of the objective lens 120 and correcting the position of the collimator 140.

Hereinafter, the driving method of the optical drive shown in FIG. 1 will be described in more detail.

The control unit 135 according to an embodiment performs the servo initialization routine as shown in FIG. 2 according to the loading signal of the disc-shaped medium 110. This initialization routine performs a first compensation step as described above.

As a first compensating step, after measuring the temperature of the objective lens 120, calculate the correction distance of the collimator 140, and then operate the actuator 150 to transfer the collimator 140 to a given position. At this time, the initial position of the collimator 140 is determined as a factory default value, and when the medium 110 is loaded, the collimator 140 is transferred to the reference position. This transfer to the reference position occurs when power is supplied to the optical drive or when the medium 110 is loaded thereafter. After completing the above process, after correcting the position of the collimator 140 according to the detection temperature of the objective lens 120, the entire optical apparatus is operated according to the existing procedure to determine the type of the medium using the light reflected from the medium. The main routine 30 of FIG. 3 is performed. As described above, the second compensation step periodically measures the temperature of the objective lens 120 during the process of writing or reading the medium in the main routine, and accordingly calculates the correction distance of the collimator 140 and then the actuator. Operation 150 moves the collimator 140 to a given position. In the case of the wake-up 41 in the standby state 140, the position of the collimator 140 is changed through the above-described process. As described above, the present invention performs spherical aberration correction according to temperature change of the objective lens through an initialization process, a write process, and a restart process. As described above, the present invention corrects the position in real time according to the temperature instead of moving the spherical aberration correcting element to the default position or continuously using the once adjusted spherical aberration correcting element position as in the conventional method.

4 and 5 illustrate a specific embodiment of the spherical aberration compensation method according to the present invention, which is a flowchart in terms of a program function.

First, referring to FIG. 4, the servo startup function SrvStartUp 41 is called as an initialization step. The servo startup function 41 first calls the initial position transfer function CL_Home_position 42 of the collimator and then calls the objective lens temperature detection function ReadTMPO 43. By the above two functions, the collimator is transferred to the initial position, and the temperature (Now_TMPO) of the objective lens at this time is detected. The detected temperature (Now_TMPO) and the initial reference temperature (Ref_TEMPO) are compared to within an allowable reference value, for example, ± 10 degrees, and the existing data type detection function (BDLDON_DiskID) 47 is called. When the difference is more than ± 10 degrees, the collimator correction position SAPOS is calculated according to the temperature difference.

In calculating the correction position SAPOS, the temperature difference TmpoGap of the measured temperature No_TMPO to the reference temperature Ref_TMPO is first determined in the temperature difference calculation step 45. Then, in step 46, the corrected position value of the collimator is obtained. In this step 46, for example, the correction distance may calculate the correction position value based on 0.685 mu m / deg. Therefore, the calibration position SAPOS of the collimator may be calculated by a formula in which a correction distance is accumulated at the current correction position, that is, an expression expressed as "SAPOS ± correction distance". Through this process, after calculating the collimator correction position, the lens position correction function (SetSAPOS) is called.In addition, the temperature (Now_TMPO) measured at this stage is stored in a separate variable (OldTMPO) to be used as reference data for the next temperature difference comparison. Can be. After the location of the collimator is modified as described above, the data type detection function BDLDON_DiskID is called (47). In this function, various kinds of information stored in the medium are read, thereby setting the operating conditions of the optical drive.

FIG. 5 is a flowchart illustrating a routine after the process of FIG. 4. After the initialization function SRVStartup is called, the main function Main and 51 is called. After the main function 51 is called, it is first determined whether the current operation mode is the write or read mode 52, so that the temperature measurement function (ChkOPUTemperature, 53) accompanying the write / read mode is called or in the standby mode 60. To fulfill. In the write / read mode, temperature measurement and collimator position correction are called by periodic interrupts as described above. The temperature measuring function ChkOPUTemperature calls the temperature detection function ReadTMPO to measure the temperature (Now_TMPO) of the objective lens (54). Then, the difference between the temperature (Old_TMPO) measured in the previous step and the newly measured temperature (Now_TMPO) is obtained (55). For example, if there is a difference of ± 5 degrees or more, the collimator according to the temperature difference in the next step (56). Correct the location. Since the main routine involves the process of recording or reading information about the medium, more rigorous spherical aberration correction is required, so that spherical aberration correction may occur over a narrow temperature range, e.g. at least ± 5 degrees, compared to the initialization stage. To help. If there is a temperature difference within ± 5 degrees, the process shifts from step 55 to step 57 to return to the beginning of the main routine 51.

On the other hand, if it is not a read / write step in the initial determination step 52 of the main routine 51, the process shifts to the standby or sleep mode 60. In this mode, a restart is initiated and the Pause / wakeup function is called. In this function, as described above, the temperature measurement function ReadTMP 62 is called, followed by a temperature difference 63 based on a wider temperature range, for example, ± 20 degrees. The range is satisfied, and then, in step 64, the function for adjusting the collimator position according to the temperature difference (CL_Auto_Adjust) is called to correct the position of the collimator (64, 65), and then returns to the may routine 51. do.

6, 7, 8 show the test results of the optical drive according to the present invention.

6 shows the focus error FE and tracking error TE before (left) and after (right) the position correction of the collimator. As can be seen from FIG. 6, the present invention significantly improves the error signal according to the temperature change.

Fig. 7 shows signal characteristics when the spherical aberration of the objective lens is compensated by the modification of the collimator position in accordance with the present invention before the disk check in the initialization routine. As shown, a good signal was obtained that was comparable to that at low temperatures even at high temperatures.

8 and 9 show two types of BD (Blue-ray Disk) media, which are lands and pits of a BD-ROM (Blue-ray Disk-Read only Memory) BD-R (Blue-ray Disk-Recordable). As a comparison of the jitter values for PIT), FIG. 8 shows a result according to the conventional method and FIG. 9 according to the method of the present invention. As shown, it can be seen that the increase in jitter value with increasing temperature according to the present invention is gentle compared to the conventional method and the difference is reduced.

According to the present invention, it is possible to suppress the media type misrecognition and the automatic adjustment failure due to the spherical aberration of the plastic objective lens having a large thermal deformation during temperature change. This makes it possible to stably maintain the level down, defocus, focus balance, track balance, jitter, and the like of the servo signal. In addition, in the development of new products, it is possible to reduce confusion and additional tuning time due to the application of various spherical aberration correction systems for each optical pickup unit. In addition, it is possible to minimize the dispersion of media correspondence due to the performance deviation of each optical pickup unit or optical drive.

1 is a schematic configuration diagram of an optical drive according to the present invention.

2 is a flowchart showing an example of an initialization routine (step) in the optical drive driving method according to the present invention.

3 is a flowchart showing an example of a main routine (step) in the optical drive driving method according to the present invention.

4 is a program flow diagram related to an initialization routine (step) in the optical drive driving method according to the present invention.

5 is a program flow diagram related to a main routine (step) in the optical drive driving method according to the present invention.

6 shows the focus error FE and tracking error TE before (left) and after (right) the position correction of the collimator.

Fig. 7 shows signal characteristics when the collimator position is corrected before the disk check in the initialization routine of the optical drive driving method according to the present invention.

8 and 9 show two types of BD (Blue-ray Disk) media, which are lands and pits of a BD-ROM (Blue-ray Disk-Read only Memory) BD-R (Blue-ray Disk-Recordable). As a comparison of the jitter values for PIT), FIG. 8 shows a result according to the conventional method and FIG. 9 according to the method of the present invention.

Claims (7)

Light source; An objective lens provided on an optical path between the light source and the optical medium to face the optical medium; A photo detector for detecting light reflected from the optical medium; A temperature sensor detecting a temperature of the objective lens; A collimator provided between the objective lens and the light source to control light incident on the objective lens; A beam splitter provided on an optical path between the collimator and the light source to direct light from the light source to the optical medium, and to reflect light reflected from the optical medium to the optical detector; A collimator actuator for adjusting the optical distance of the collimator to the objective lens; And And a controller configured to control the collimator actuator to detect the temperature of the objective lens by the temperature sensor and correct the optical distance according to the position correction value of the collimator corresponding thereto. The control unit, Compensating for the optical distance in the step of entering the operating state from the inoperative state with the medium loaded, In the initialization step of loading the medium, after determining the position correction value, the medium is detected, In the information processing of the medium, during the information processing routine, the position correction value of the collimator is determined by an open-loop compensation distance determination routine called by a cyclic interrupt. delete delete delete A light source, an objective lens facing the optical medium, an optical detector for detecting the light reflected from the optical medium, a temperature sensor for detecting the temperature of the objective lens, and controlling the light incident on the objective lens between the objective lens and the light source And a beam splitter for advancing the light from the light source between the collimator and the light source toward the optical medium while passing the light from the light source toward the optical medium, and adjusting the optical distance of the collimator to the objective lens. A drive of an optical drive having a collimator actuator and a controller for controlling the collimator actuator in accordance with the temperature of the objective lens, including an internal lookup table including data corresponding to the position correction value of the collimator corresponding to the temperature of the objective lens In the method, Detecting loading of media to the optical drive; A first correction step of measuring the temperature of the objective lens facing the medium, correcting the position of the collimator by calculating a correction value from the reference position of the collimator from the measured temperature after the medium is loaded; Irradiating light onto the medium through the collimator and the objective lens and determining the type of the medium from the reflected light signal; Performing an information processing process on the medium associated with information recording or reading corresponding to the medium type; In the step of performing the information processing process, the second temperature for periodically correcting the position of the collimator by periodically measuring the temperature of the objective lens, calculating the correction value from the reference position of the collimator from the temperature measured for each period Correction step; Waiting for a return to the information processing step while the information processing on the medium is stopped; And A third correction step of measuring the temperature of the objective lens when returning from the waiting step to the information processing step, calculating a correction value from the reference position of the collimator from the measured temperature, and correcting the position of the collimator Optical drive driving method comprising a. delete delete

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