• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    PURPOSE: A disc defect preventing device and a method thereof are provided to take measures for situations possibly generating defect on a disc by close approach of an objective lens. CONSTITUTION: A method for preventing defect of a disc includes the steps of carrying out focus pull-in operation by a pickup, and forcibly moving the pickup away from a disc by applying a strong DC current to an actuator. During the focus pull-in, if the pickup approaches the disc suddenly by external impact, a focus error signal exhibits a waveform dropping from a predetermined DC level and a pull-in signal level drops to an initial value smaller than a threshold value. If the dropped level of the pull-in signal continues for a predetermined time, the pickup moves to the disc and an objective lens comes into contact with the disc. Therefore, before the objective lens contacts the disc, the strong DC current is applied to the actuator.
    公开号:KR20040011652A
    申请号:KR1020020044629
    申请日:2002-07-29
    公开日:2004-02-11
    发明作者:최병호；정수열；마병인；박인식
    申请人:삼성전자주식회사；
    IPC主号:
    专利说明:

    Control method and apparatus for preventing disc scratches {Control method and apparatus for preventing object lens from scratching disc}
    [9] The present invention relates to a control method and apparatus for preventing disc scratches caused by an objective lens.
    [10] Recently, in the optical disc system, an objective lens having a higher aperture ratio and a shorter wavelength laser diode are used to increase the recording density of the optical disc. The higher the aperture ratio and the shorter the wavelength, the shorter the focal length, so that even with small disturbances, the objective lens easily hits the optical disk, causing scratches on the surface of the disk. Next-generation high-density optical discs, such as BD (Blu Disc), aim to have a recording density of approximately five times that of DVD. Therefore, high aperture ratio objective lenses and short laser (Blu laser) are used. Thus, the possibility of scratching the disk by the objective lens becomes very high. In the portable system, disturbance occurs more frequently because the distance between the optical disk and the objective lens is narrow and the use environment is not constant.
    [11] Accordingly, it is an object of the present invention to provide a control method and apparatus for preventing disc scratches caused by an objective lens in an optical disc system.
    [12] It is still another object of the present invention to provide a method and apparatus for preventing disc scratches caused by an objective lens in a mobile optical disc system.
    [1] 1 is a schematic diagram of an apparatus according to a preferred embodiment of the present invention,
    [2] 2 is a detailed structural diagram of the pickup 1 of FIG.
    [3] 3 is a reference diagram for explaining a situation in which a method for preventing a disc scratch by an objective lens is performed according to the present invention;
    [4] 4 is a reference diagram for explaining another situation in which a method for preventing a disc scratch by an objective lens is performed according to the present invention;
    [5] 5 is a reference diagram for explaining another situation in which a method for preventing a disc scratch by an objective lens is performed according to the present invention;
    [6] 6 is a flowchart for explaining a method for preventing disk scratches by an objective lens according to an embodiment of the present invention;
    [7] 7 is a flowchart illustrating a method for preventing disk scratches by an objective lens according to another embodiment of the present invention;
    [8] 8 and 9 are signals measured for implementing a control method for preventing disc scratches by an objective lens according to the present invention based on an optical disc system having a pickup equipped with a laser diode having an aperture ratio of 0.7 or more and a wavelength of 500 nm or less. .
    [13] In order to achieve the above object, a method for preventing disc scratches by an objective lens, comprising: (b) focus pull-in; And (c) controlling the objective lens to move away from the disk if the level of the pull-in signal continues below the predetermined threshold level for a predetermined threshold time.
    [14] The predetermined threshold time of step (c) is preferably set to the time that the objective lens should not touch the disk when the actuator driving the pickup moves at a substantial maximum speed.
    [15] In the step (c), it is preferable to apply a DC signal to an actuator for driving the pickup equipped with the objective lens.
    [16] In addition, the above object is a method for preventing disk scratches by the objective lens, comprising: (a) initializing a pull-in signal; (b) focus pull-in; (c1) checking the level of the pull-in signal; (c2) checking the duration if the level of the pull-in signal is lowered below a predetermined threshold level; And (c3) controlling the pickup on which the objective lens is mounted away from the disc when the duration lasts more than a predetermined threshold time.
    [17] The method further includes (c4) leaving the actuator for driving the pickup with the objective lens intact if the duration does not last longer than a predetermined threshold time, or (c5) the duration lasting longer than a predetermined threshold time. Otherwise, the method further comprises outputting an average value of the drive signal previously provided to the actuator for driving the pickup equipped with the objective lens.
    [18] On the other hand, according to another field of the present invention, the object is a device for preventing disk scratches by the objective lens, the pickup is equipped with the objective lens; An actuator for driving the pickup; A signal detector for detecting a pull-in signal from the pickup; And a control unit for controlling the actuator to move the objective lens away from the disk when the level of the pull-in signal detected by the signal detector lasts less than a predetermined threshold level for more than a predetermined threshold time. Is achieved.
    [19] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.
    [20] 1 is a schematic diagram of an apparatus according to a preferred embodiment of the present invention.
    [21] Referring to FIG. 1, the device according to the present embodiment is a device having a function of preventing disk scratches by an objective lens, and includes a pickup 1, an actuator 2, a signal detector 4, and a controller 7. It includes. The control unit 7 has a drive 3 and a controller 7. Reference numeral 6 denotes a spindle motor for rotating the disk 100.
    [22] The pickup 1 is equipped with an objective lens (not shown) for irradiating a laser beam to the disk 100. The actuator 2 drives the pickup 1. The signal detector 4 detects a pull-in signal based on a signal output from a photodiode (not shown) mounted on the pickup 1. The controller 5 checks the level of the pull-in signal detected by the signal detector 4, and if the level of the pull-in signal continues below the predetermined threshold level for a predetermined time or more, the objective lens is moved away from the disk 100. A control signal for controlling the loss is output to the drive 3. The drive 3 outputs a drive signal corresponding to the control signal from the controller 5 to the actuator 2. That is, the drive 3 applies a strong DC signal having a high level to the actuator 2 to move the pickup 1 away from the disc 100 and then stop the actuator 2.
    [23] The threshold time is set to the time at which the objective lens should not touch the disc 100 when the actuator 2 moves at a substantial maximum speed. The threshold level is a level at which the objective lens mounted on the pickup 1 should not hit the disk 100 when the pickup 1 moves close to the disk 100 due to disturbance during focus control, and is set to an appropriate value by actual measurement. .
    [24] 2 is a detailed structural diagram of the pickup 1 of FIG.
    [25] Referring to FIG. 2, the pickup 1 includes a laser diode LD 15, a collimate lens 14, an objective lens 11, a beam splitter 12, and a photodiode PD 13.
    [26] When the laser diode LD 15 oscillates a laser, the collimate lens 14 turns the divergent light laser into a parallel light laser beam. The objective lens 11 connects the laser beam to the reflective surface of the disk 100. The connected laser beam is incident on the recording surface of the disk 100 and reflected again. The beam splitter 12 separates the incident laser beam and the reflected laser beam and changes the path so that the reflected laser beam reaches the photodiode PD 13 side. The photodiode PD 13 is a light receiving element for receiving the reflected laser beam, and has a plurality of divided light receiving sections. Two split light-receiving units are referred to as two-split photodiodes, four are four-split photodiodes, and eight are eight-split photodiodes.
    [27] In the present invention, the pull-in signal refers to a sum signal of signals collected by a plurality of split light receiving units of the photodiode 13 or a signal whose high frequency component is filtered by a suitable low pass filter. The focus error signal necessary for controlling the focus of the laser beam to be properly focused on the recording surface of the disk 100 is also generated based on the signals collected by the plurality of divided light receiving units of the photodiode 13.
    [28] On the other hand, since the components of the pickup 1 and the arrangement of the components are independent of the features of the present invention, the components shown in FIG. 2 and the structure thereof are not necessarily essential and may have other structures as necessary. Of course. However, the photodiode 13 for generating the pull-in signal according to the present invention is an essential component. However, the arrangement position of the photodiode 13 with respect to other components may be variously determined.
    [29] 3 is a reference diagram for explaining a situation in which a method for preventing a disc scratch by an objective lens is performed according to the present invention.
    [30] Referring to FIG. 3, the pickup 1 is moved according to the present invention when the objective lens 11 moves close to the disk 100 so as to scratch the disk 100 while the pickup 1 performs the focus pull-in operation. The focus error signal, the pull-in signal, and the actuator driving signal generated in the process of moving the direction away from the disk 100 can be checked.
    [31] When the laser beam focuses on the recording surface of the disc 100, that is, when focus pull-in is performed, the level of the pull-in signal increases from the initial value to the predetermined DC level ΔV1. If disturbance is applied while the focus pull-in is performed and the pickup 1 suddenly approaches the disc 100, a partial waveform B appears in the focus error signal while the predetermined DC level is maintained and the level falls down. . Then, the level of the pull-in signal falls to a value smaller than the threshold level according to the present embodiment, that is, the initial value. The fact that the level of the pull-in signal has dropped to the initial value and lasts for a predetermined time Δt1 indicates that the pickup 1 continues to move toward the disc 100, and thus the objective lens may hit the disc 100. Therefore, before the objective lens 11 of the pickup 1 touches the disk 100, a strong DC current is applied to the actuator 2 to force the pickup 1 to move away from the disk 100. The actuator drive signal is continuously maintained at the DC level dropped by the predetermined level V2 at the time A after the predetermined time T1 has elapsed. Since the pickup 1 is moved away from the disk 100 and then stopped, the level of the pull-in signal rises again and falls to an initial value.
    [32] 4 is a reference diagram for explaining another situation in which a method for preventing a disk scratch by an objective lens is performed according to the present invention.
    [33] Referring to FIG. 4, a focus error signal, a pull-in signal, and a signal according to the present invention when the objective lens 11 moves away from the disc 100 due to disturbance while the pickup 1 performs the focus pull-in operation. The actuator drive signal can be checked.
    [34] When the laser beam is focused on the recording surface of the disc 100, that is, when focus pull-in is performed, the level of the pull-in signal increases from the initial value to a predetermined DC level. If disturbance is applied while the focus pull-in is performed and the pickup 1 suddenly moves away from the disc 100, a partial waveform appears in the focus error signal while the predetermined DC level is kept up. Then, the level of the pull-in signal falls to a level smaller than the threshold level according to the present embodiment, that is, the initial value. The fact that the level of the pull-in signal has dropped to the initial value and lasts for a predetermined time Δt1 indicates that the pickup 1 is out of focus control, and therefore, the objective lens 11 may hit the disc 100 at any time. As a result, a strong DC current is applied to the actuator 2 to move the pickup 1 away from the disk 100 and then stop. Strong DC current continues to be transmitted to the actuator 2 until the pickup 1 stops. It can be seen that the actuator driving signal is maintained at the DC level dropped by a predetermined level after the time B after the predetermined time Δt1 elapses. In addition, the pull-in signal keeps the initial value because the pickup 1 is stopped after being moved away from the disk 100.
    [35] 5 is a reference diagram for explaining another situation in which a method for preventing a disc scratch by an objective lens is performed according to the present invention.
    [36] Referring to FIG. 5, the focus error signal when the laser beam spot passes through a portion where a scratch is formed, such as a black dot formed on the disk 100, while the pickup 1 performs a focus pull-in operation, The pull-in signal and actuator drive signal can be checked.
    [37] When the laser beam is focused on the recording surface of the disc 100, that is, when focus pull-in is performed, the level of the pull-in signal increases from the initial value to a predetermined DC level ΔV1. If the laser beam spot passes through a scratched portion such as a black dot while focus pull-in is performed, the partial waveform C where the focus error signal is maintained at a predetermined DC level and then rises up is generated. However, the partial waveform C has a lower level than that in FIG. 3 and has a sin waveform. Then, the level of the pull-in signal falls to a level lower than the threshold level according to the present embodiment, that is, the initial value. However, the level of the pull-in signal falls back to the initial value and does not last longer than the predetermined threshold time DELTA t1 and when the predetermined time DELTA t2 shorter than the threshold time DELTA t1 elapses, the previous DC level is restored. This does not mean that the pickup 1 continues to move towards the disc 100, so that the drive 3 does not perform any operation or the average value of the signal previously applied to the actuator 2, that is, the actuator drive signal. Output to the actuator (2).
    [38] A method for preventing a disk scratch according to the present invention based on the configuration as described above is as follows.
    [39] 6 is a flowchart for explaining a method for preventing disc scratches by an objective lens according to an embodiment of the present invention.
    [40] The control unit 7 turns off the laser diode 15 or moves the pickup 1 to a position where the laser beam emitted from the objective lens 11 is reflected from the recording surface of the disk 100 and is not incident on the photodiode 13. The initial value of the pull-in signal is set in the moved state (step 601). The initial value is set to a value that can easily check the level change of the pull-in signal in various situations as described above with reference to FIGS. 3, 4 and 5. The control unit 7 performs focus control so that the laser beam spot is correctly focused on the recording surface of the disc. That is, focus pull-in 602. When the focus is pulled-in, the amount of light collected by the photodiode PD 13 is in the highest state, and thus the pull-in signal obtained at this time is a signal having an appropriate DC level. Therefore, by checking the level of the pull-in signal, it is possible to determine whether the current focus pull-in is properly performed. While the laser beam spot is correctly focused, the level of the pull-in signal maintains a predetermined DC level.
    [41] On the other hand, the control unit 7 checks whether the level of the pull-in signal is lower than the predetermined threshold level Vref and then continues for the predetermined threshold time DELTA t1 (step 603).
    [42] If the level of the pull-in signal does not become lower than the predetermined threshold level Vref during the predetermined threshold time T1, the control section 7 does not regard the pickup 1 as moving toward the disk 100, and thus continues the focus control. Perform (step 604).
    [43] If the level of the pull-in signal is lower than the predetermined threshold level Vref for the predetermined threshold time T1, the control unit 7 considers that the pickup 1 is moving toward the disk 100 and causes the pickup 1 to be moved to the disk 100. In step 605, the actuator driving signal for moving or moving away from the actuator and stopping the actuator is output to the actuator 2.
    [44] 7 is a flowchart for explaining a method for preventing disk scratches by an objective lens according to another embodiment of the present invention.
    [45] Referring to FIG. 7, the controller 7 turns off the laser diode 15 or the position where the laser beam emitted from the objective lens 11 is reflected from the recording surface of the disk 100 and is not incident to the photodiode 13. In step 701, the initial value of the pull-in signal is set while the pickup 1 is moved. The initial value is set to a value that can easily check the level change of the pull-in signal in various situations as described above with reference to FIGS. 3, 4 and 5. The control unit 7 performs focus control so that the laser beam spot is correctly focused on the recording surface of the disc. That is, focus pull-in 702. When the focus is pulled-in, the amount of light collected by the photodiode PD 13 is in the highest state, and thus the pull-in signal obtained at this time is a signal having an appropriate DC level. Therefore, by checking the level of the pull-in signal, it is possible to determine whether the current focus pull-in is properly performed. While the laser beam spot is correctly focused, the level of the pull-in signal maintains a predetermined DC level.
    [46] On the other hand, the controller 7 checks whether the level of the pull-in signal is lower than the predetermined threshold level Vref (step 703). If the level of the pull-in signal is not lower than the predetermined threshold level Vref, focus control is continued (step 704).
    [47] If the level of the pull-in signal is lower than the predetermined threshold level Vref, it is checked whether the level lasts more than the predetermined threshold time T1 (step 705). If the level of the pull-in signal is lower than the predetermined threshold level Vref but does not last for the predetermined threshold time DELTA t1, the controller 7 does not regard the pickup 1 as moving toward the disc 100, and thus the controller ( 7) outputs the average value of the drive signal, that is, the drive average value previously outputted to the actuator 2, to the actuator 2 (step 706).
    [48] If the state where the level of the pull-in signal is lower than the predetermined threshold level Vref lasts more than the predetermined threshold time T1, the control unit 7 considers that the pickup 1 is moving toward the disc 100, and the pickup 1 Is moved away from the disk 100, or outputs a drive signal to the actuator 2 to stop and move (step 707).
    [49] 8 and 9 illustrate signals measured to implement a control method for preventing disc scratches by an objective lens according to the present invention based on an optical disc system having a pickup equipped with a laser diode having an aperture ratio of 0.7 or more and a wavelength of 500 nm or less. Shows
    [50] Referring to FIG. 8, an actuator drive signal, a focus error signal, and a pull for driving the actuator 2 so that the pickup 1 moves closer to and away from the disk 100, that is, the pickup 1 moves up and down. Show the signal of-. Accordingly, it can be seen that the pull-in signal maintains a predetermined DC level when the focus control is in progress, that is, when the focus pull-in is performed.
    [51] Referring to Fig. 9, the actuator drive signal, the focus error signal, and the pull-in signal obtained when the method for preventing disc scratches by the objective lens according to the present invention can be seen. If the pull-in signal maintains a predetermined DC level and then falls to an initial value and passes the predetermined threshold time Δt1 or more, the actuator driving signal is a direction in which the pickup 1 moves away from the disk 100 after the time E after the threshold time Δt1 elapses. The predetermined DC level is maintained. Accordingly, it can be seen that the pickup 1 is moved in a direction away from the disk 100 and then stopped.
    [52] As described above, according to the present invention, there is provided a control method and apparatus that can prevent a disc scratch by appropriately dealing with a situation in which the objective lens may move closer to the disc and cause a scratch on the disc by the focus pull-in disturbance. do. In particular, the present invention has a significant effect in a high density recording system in which an objective lens (pickup) and a disc are located closer to each other due to a short focal length, or in a mobile optical disc system in which disturbance is more likely to occur. .
    权利要求:
    Claims (17)
    [1" claim-type="Currently amended] In the method for preventing disc scratches by the objective lens,
    (b) focus pull-in; And
    and (c) controlling the objective lens to move away from the disk if the level of the pull-in signal lasts below a predetermined threshold level for a predetermined threshold time.
    [2" claim-type="Currently amended] The method of claim 1,
    And the predetermined threshold time of step (c) is set to the time that the objective lens should not touch the disc when the actuator driving the pickup moves at a substantial maximum speed.
    [3" claim-type="Currently amended] The method of claim 1,
    Step (c) is
    And applying a DC signal to an actuator for driving a pickup equipped with the objective lens.
    [4" claim-type="Currently amended] The method of claim 1,
    Step (c) is
    And applying a DC signal to an actuator for driving a pickup equipped with the objective lens to stop the actuator.
    [5" claim-type="Currently amended] In the method for preventing disc scratches by the objective lens,
    (a) initializing a pull-in signal;
    (b) focus pull-in;
    (c1) checking the level of the pull-in signal;
    (c2) checking the duration if the level of the pull-in signal is lowered below a predetermined threshold level; And
    and (c3) controlling the pickup with the objective lens to move away from the disc if the duration lasts more than a predetermined threshold time.
    [6" claim-type="Currently amended] The method of claim 5,
    and (c4) leaving the actuator for driving the pickup with the objective lens unchanged if the duration does not last longer than a predetermined threshold time.
    [7" claim-type="Currently amended] The method of claim 5,
    and (c5) outputting an average value of a drive signal previously provided to an actuator for driving the pickup equipped with the objective lens if the duration does not last longer than a predetermined threshold time.
    [8" claim-type="Currently amended] The method of claim 5,
    Step (a) is
    And the pull-in signal comprises initializing to a level lower than the DC level to facilitate detecting a predetermined DC level that persists during focus pull-in.
    [9" claim-type="Currently amended] The method of claim 5,
    And the predetermined threshold of step (c2) is set to the time that the objective lens should not touch the disc when the actuator driving the pickup moves at a substantial maximum speed.
    [10" claim-type="Currently amended] The method of claim 5,
    Step (c3) is
    And applying a DC signal to an actuator for driving a pickup equipped with the objective lens.
    [11" claim-type="Currently amended] The method of claim 5,
    Step (c3) is
    And applying a DC signal to an actuator for driving a pickup equipped with the objective lens to stop the actuator.
    [12" claim-type="Currently amended] The method according to any one of claims 1 to 11,
    The pull-in signal may be a sum signal of signals collected by a plurality of split light receiving units of a photodiode, or a signal obtained by passing a low pass filter through the sum signal.
    [13" claim-type="Currently amended] In the device for preventing the disk scratches by the objective lens,
    A pickup equipped with the objective lens;
    An actuator for driving the pickup;
    A signal detector for detecting a pull-in signal from the pickup; And
    And a control unit for controlling the actuator to move the objective lens away from the disc when the level of the pull-in signal detected by the signal detector lasts less than a predetermined threshold level for more than a predetermined threshold time.
    [14" claim-type="Currently amended] The method of claim 13,
    And the threshold time is set to the time that the objective lens should not touch the disc when the actuator moves at a substantial maximum speed.
    [15" claim-type="Currently amended] The method of claim 13,
    The control unit
    And applying a DC signal to the actuator.
    [16" claim-type="Currently amended] The method of claim 13,
    The control unit
    Apparatus for stopping the actuator by applying a DC signal to the actuator.
    [17" claim-type="Currently amended] The method according to any one of claims 12 to 16,
    And the pull-in signal is a sum signal of signals collected by a plurality of split light receivers of a photodiode mounted on the pickup, or a signal that passes the sum signal through a low pass filter.
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2002-07-29|Application filed by 삼성전자주식회사
    2002-07-29|Priority to KR1020020044629A
    2004-02-11|Publication of KR20040011652A
    2009-01-13|Application granted
    2009-01-13|Publication of KR100878530B1
    优先权:
    申请号 | 申请日 | 专利标题
    KR1020020044629A|KR100878530B1|2002-07-29|2002-07-29|Control method and apparatus for preventing object lens from scratching disc|
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