JP4525491B2 - Optical disc driving apparatus, optical disc apparatus and driving method thereof - Google Patents

Description

  The present invention relates to an optical disk drive apparatus that performs at least one of signal recording and reproduction using near-field light, an optical disk apparatus equipped with this drive apparatus, and a drive method thereof.

  In recent years, in order to improve the recording density of an optical disk using a laser beam, an optical disk apparatus that records or reproduces a signal using near-field light has been proposed. In an optical disc apparatus using near-field light, the gap between the disc and the end surface of a SIL (Solid Immersion Lens) installed on a condensing element such as an objective lens unit is controlled to a distance (near field) where near-field light is generated. There is a need. This distance is generally 1/4 to 1/2 of the wavelength of the input laser beam. For example, when a 400 nm blue-violet laser is used, the thickness is about 200 nm.

  For this reason, an optical recording / reproducing apparatus using near-field light has an overshoot that occurs at a distance of 1 μm or less at the start of control of the gap, which is not particularly problematic in a far-field optical system such as a DVD (Digital Versatile Disk). Then it becomes a problem. That is, even if an overshoot of 1 μm or less occurs at the start of control, the SIL collides with the disk, causing damage to both.

  In order to solve such a problem, for example, a threshold value for determining the near field state is set, and the SIL is brought close to the disk until the threshold value is detected. After the threshold value is detected, the servo voltage is added to the approach voltage. Has been disclosed (for example, see Patent Document 1).

Further, in an optical disc apparatus using near-field light, dust such as dust and dust attached to the disc becomes an important problem in gap control. Since many dusts have a width (height) larger than the target value of the gap, if dust adheres on the disk, gap control becomes impossible. Therefore, there is a technique in which the disk is rotated at an arbitrary number of revolutions before the signal is recorded or reproduced on the disk, and dust attached to the disk is blown off to the outer peripheral side of the disk (see, for example, Patent Document 2). ).
Japanese Patent Laying-Open No. 2004-30821 (paragraph [0023] etc., FIG. 5 and FIG. 6) JP 2002-319149 A (paragraph [0018], FIG. 2)

  However, there is a concern that dust on the disk cannot be removed by simply rotating the disk. In particular, when the disk is removable and there is no disk cartridge or the like, there is a high possibility that dust will adhere to the disk. Even if dust on the disk is removed, gap control cannot be performed if dust adheres to the objective lens or the like. Further, when dust is attached to a disk or a lens, it can be automatically detected, and it is desirable that gap servo is appropriately performed.

  In view of the circumstances as described above, an object of the present invention is to provide an optical disc drive device capable of appropriately controlling the gap by removing dust on the disc, an optical disc device equipped with the optical disc drive device, and a driving method thereof. is there.

  In order to achieve the above object, an optical disc driving apparatus according to the present invention is disposed opposite to a light source that emits light and a disc having a recording surface capable of recording a signal, and the light emitted from the light source is placed close to the light source. A condensing element capable of condensing the recording surface as field light, and a contact-type cleaning mechanism for cleaning at least one of the recording surface and the condensing element in contact with the recording surface and the condensing element It comprises.

  In the present invention, since a contact-type cleaning mechanism is provided, dust is easily removed. Thereby, after cleaning, appropriate gap control as described later can be performed.

  As light, for example, blue or blue-violet laser light having a wavelength of about 400 nm is used. However, the present invention is not limited to this, and laser light having a wavelength smaller than 400 nm or larger than 400 nm may be used. In addition, light other than visible light may be used.

  The condensing element refers to an objective lens or an optical system including the objective lens, and may have a function of condensing on a disk as near-field light.

  In the present invention, the optical disk drive apparatus includes a gap detection unit that detects a gap between the light condensing element and the disk, and after the cleaning surface cleans at least one of the recording surface and the light condensing element, Gap control means for controlling the gap between the condensing element and the rotating disk to be constant based on a detection signal from the gap detection means.

  In the present invention, the gap control means includes a first control means for controlling the gap while rotating the disk at a first rotation speed by the rotation mechanism, and after the control by the first control means, And a second control means for controlling the gap while rotating the disk at a second rotational speed higher than the first rotational speed. The first number of rotations is preferably a lower number of rotations than the number of disk rotations during signal recording or reproduction. For example, when one of the recording surface of the disk and the light condensing element is cleaned, dust may remain on either one of them. In particular, when dust remains on the disc, if the disc rotates at high speed, the condensing device may be damaged or destroyed by colliding with the dust on the disc at high speed. is there. On the other hand, even if dust remains on the light collecting element, the disk may be damaged. However, the present invention can solve such a problem. In the present invention, as described above, the present invention is not limited to “when either one of the recording surface of the disk and the light condensing element is cleaned”, but includes a case where both are cleaned.

  In the present invention, the gap detecting unit detects a return light amount from the disk of the light emitted from the light source, and the first control unit detects the return light amount during at least one rotation of the disk. The number of times exceeding a predetermined threshold is measured, and if the measured number is less than the predetermined number of times threshold, control is performed to shift to the second control means. Thereby, the bad influence by dust can be prevented reliably and favorable gap control becomes possible. In the present invention, in particular, the case where only one of the disk and the light collecting element is cleaned is applied. However, the case where both are cleaned is also included. The predetermined threshold value may be a light amount in which the condensing element (an end surface facing the recording surface) is in a far field state or a light amount in a near field state.

  In the present invention, the optical disk drive device controls the tilt of the light condensing element with respect to the recording surface to be constant after at least one of the recording surface and the light condensing element is cleaned by the cleaning mechanism. A tilt control means is further provided. Thereby, tilt control can be appropriately performed. The tilt control includes a case where the tilt control is performed in real time so as to follow, for example, a disk shake or the like during the rotation of the disk, such as during signal recording or reproduction. However, the present invention is not limited to this, and as described in the next invention, so-called initial tilt adjustment, for example, adjusting the tilt of the condensing element, for example, before recording or reproducing a signal is also used in the present invention. Included in control.

  That is, the tilt control means has adjustment means for adjusting the tilt while moving the light condensing element in a state where the light condensing element is in contact with the disk when the disk is not rotating. In the present invention, since the tilt adjustment is performed in a state where the light condensing element is in contact with the disk, the tilt can be surely eliminated. Thereby, gap control can be appropriately performed thereafter.

  In the present invention, for example, the cleaning mechanism includes a cleaning tape that contacts the condensing element, and a condensing element cleaning mechanism that performs cleaning by moving the cleaning tape relatively while contacting the condensing element. Have. The condensing element cleaning mechanism may further include a mechanism that relatively separates and contacts the condensing element and the cleaning tape in addition to the cleaning tape.

  In the present invention, for example, the cleaning mechanism has a disk cleaning mechanism that moves relative to the disk and cleans it while being in contact with the recording surface. The disk cleaning mechanism may further include a mechanism for relatively separating and contacting the disk and a member that contacts and cleans the disk.

  An optical disc apparatus according to the present invention includes a light source that emits light, a rotating mechanism that rotates a disc having a recording surface capable of recording a signal, and the light emitted from the light source that is disposed opposite to the disc. As the near-field light, a condensing element capable of condensing on the recording surface of the rotating disk, and at least one of the recording surface and the condensing element in contact with the recording surface and the condensing element A contact-type cleaning mechanism for cleaning; and a recording / reproducing mechanism capable of at least one of recording the signal on the disk and reproducing the recorded signal. In other words, the optical disc apparatus according to the present invention is obtained by adding the constituent elements of the “recording / reproducing mechanism” to the optical disc driving apparatus. The recording / reproducing mechanism means a signal processing circuit, machine, software or the like necessary for recording or reproduction.

  In the driving method of the optical disc driving apparatus according to the present invention, at least one of a recording surface of a disc capable of recording a signal and a condensing element that condenses light emitted from a light source as near-field light on the recording surface is a contact type. Cleaning, and after the cleaning, rotating the disk, and controlling the gap between the condensing element and the disk to be constant while rotating the disk. .

  In the present invention, in particular, after cleaning, when the disc is not rotating, the condensing element is brought into contact with the disc, and the tilt is adjusted while moving the condensing element in a state where the condensing element is in contact with the disc. It is preferable to clean at least the light condensing element among the recording surface and the light condensing element. This is because in such initial tilt adjustment, the light condensing element is brought into contact with the disk, so that it is better to clean the light condensing element rather than the recording surface of the disk.

  As described above, according to the present invention, dust on the disk can be removed and the gap can be controlled appropriately.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an optical disc driving apparatus according to an embodiment of the present invention. The optical disk drive 1 includes an optical head 28, a servo control system 40, and a spindle motor 48. The optical head 28 includes a laser diode (LD) 31 serving as a light source, collimator lenses 32 and 46, an anamorphic prism 33 for shaping laser light, a beam splitter (BS) 34, a quarter wavelength plate (QWP) 43, and chromatic aberration correction. It has a lens 44, a laser beam expansion lens 45, a Wollaston prism 35, condensing lenses 36 and 38, a condensing element 5, photo detectors (PD) 37 and 39, an auto power controller 41, and an LD driver 42.

  The Wollaston prism 35 is composed of two prisms, and light incident on the Wollaston prism 35 is emitted as two linearly polarized lights that are orthogonal to each other. The PD 37 outputs, to the servo control system 40, an RF reproduction signal for reproducing a signal recorded on the optical disc, a tracking error signal necessary for servo control, a gap error signal, and the like.

  The servo control system 40 includes a gap servo module (focusing servo module) 51, which will be described later, a tracking servo module 52, a tilt servo module 53, and a spindle servo module 54. The tracking servo module 52 performs tracking control of the light collecting element 5 based on the tracking error signal. The tilt servo module 53 controls the tilt angle of the light collecting element 5. The spindle servo module 54 controls the rotation of the spindle motor 48.

  The auto power controller 41 outputs a predetermined signal to the LD driver 42 based on the signal output from the PD 39 so that the laser power output from the LD 31 is constant.

  Next, the operation centering on the optical system of the optical disk drive 1 will be described. For example, an optical disc 47 serving as a recording medium is set in the optical disc driving apparatus 1. Then, each servo control is performed by the servo control system 40. On the other hand, the laser light emitted from the LD 31 is converted into parallel light by the collimator lens 32 and shaped by the anamorphic prism 33. The laser light incident on the BS 34 is split by the BS 34 into light incident on the QWP 43 and light incident on the condenser lens 38. The laser light incident on the condenser lens 38 is controlled to have a constant power by the auto power controller 41 as described above. The light that has entered the QWP 43 is converted into circularly polarized light by the QWP 43, the chromatic aberration is corrected by the chromatic aberration correction lens 44, and enters the light collecting element 5 via the expansion lens 45 and the collimator lens 46.

  The laser light incident on the condensing element 5 is condensed as near-field light on the optical disc 47 as will be described later, and a signal is recorded on the optical disc 47. Alternatively, the laser light collected as near-field light on the optical disc 47 is incident on the optical disc 47 in order to read out the signal recorded on the optical disc 47, and the reflected light or diffracted light from the optical disc 47 is used as the condensing element 5. Receive. Reflected light or diffracted light from the optical disk 47 enters the BS 34 via the condensing element 5 as return light via the collimator lens 46, the expansion lens 45, the chromatic aberration correction lens 44, and the QWP 43. The laser light totally reflected by the BS 34 enters the PD 37 via the Wollaston prism 35 and the condenser lens 36. The PD 37 obtains an RF reproduction signal and a servo control signal, and the servo control signal is input to the servo control system 40 to perform each servo control.

  FIG. 2 is a side view showing the condensing element 5 and the optical disc 47. The condensing element 5 is disposed to face the optical disc 47. The condensing element 5 is configured by accommodating a SIL 2 and an aspheric lens 3 in a lens holder 4. The condensing element 5 is not limited to such a form, and may have any form as long as the laser light 24 can be guided to the optical disc 47 as near-field light. The end surface 2 a of the SIL 2 is disposed so as to face the recording surface 47 a of the disk 47. The lens holder 4 is installed on a triaxial actuator 6 constituting at least a part of the separation / contact mechanism. Although the triaxial actuator 6 is simplified in the figure, it is composed of, for example, a triaxial coil, a yoke, etc., and a focusing servo including a tracking servo and a gap servo when a current with a predetermined servo voltage flows through each coil. And tilt servo control.

  FIG. 3 is a side view showing a part of the optical disk drive 1. FIG. 4 is a plan view seen from the lower side of the optical disk drive 1 shown in FIG. The optical disk drive 1 includes a lens cleaning mechanism 60 that contacts the end surface 2a of the SIL 2 to clean the SIL 2, and a disk cleaning mechanism 80 that contacts the recording surface 47a of the disk 47 and cleans the recording surface 47a. ing.

  The lens cleaning mechanism 60 is disposed on the outer peripheral side of the disk 47 set on the spindle motor 48, for example. The lens cleaning mechanism 60 is a tape type cleaner as shown in FIG. 12A, for example, and includes rotating drums 63 and 64 and auxiliary rollers 65 and 66. As the rotating drums 63 and 64 rotate, the cleaning tape 61 travels along the auxiliary rollers 65 and 66. The cleaning tape 61 is made of a material such as a soft resin that does not damage the SIL 2, but is not limited thereto.

  The condensing element 5 is configured to be movable up and down at the position of the lens cleaning mechanism 60, and the end surface 2 a of the SIL 2 comes into contact with or moves away from the tape 61. As a method for this up-and-down driving, for example, driving by the triaxial actuator 6 (particularly, a gap servo coil) may be used, or a driving mechanism (not shown) different from the servo system may be used. Alternatively, not the form in which the light collecting element 5 is driven to approach the lens cleaning mechanism 60 but the form in which the lens cleaning mechanism 60 is driven to approach the light collecting element 5 is also conceivable.

  The disk cleaning mechanism 80 includes, for example, a cleaning member 82 disposed to face the recording surface 47 a of the disk 47 and a support body 81 that supports the cleaning member 82. The support 81 is configured to be lifted and lowered by a motor (not shown). The cleaning member 82 has a long shape having a length of about the radius of the disk 47, for example. The cleaning member 82 contacts the recording surface 47a to remove dust. For example, the cleaning member 82 is made of a fiber or mesh, and a material that does not damage the recording surface 47a is used. However, the cleaning member 82 is not limited to this. For example, it may be the same as the material of lens paper or the like.

  FIG. 5 is a block diagram showing an outline of the gap servo module 51. The controlled object is a triaxial actuator 6. Further, the detection amount (controlled amount) is the total reflected return light amount 24, which is detected by the PD 37 as described above. The detected total reflection return light amount 24 is normalized to 1 V, for example, by the normalization gain 18. The standardized signal is digitized by an AD (analog to digital) converter 19. The digitized total reflected return light amount is input to the data processing unit 10. The data processing unit 10 outputs a voltage for causing the SIL 2 of the light condensing element 5 to approach the optical disc 47, converted into an analog signal by a DA (digital to analog) converter 11, and output as an approach voltage 14. The A gap error signal 27 is input to the filter 13, converted to an analog signal by the DA converter 12, and output as a servo voltage 15. The approach voltage 14 and the servo voltage 15 are added and input to the driver 16, and the driver 16 drives the triaxial actuator 6 so that the gap error becomes zero.

  FIG. 6 is a block diagram showing details of the data processing unit 10.

  The data processing unit 10 receives the total reflected return light amount 24 and the gap servo switch 9. The near-field detection level setting unit 21 sets a near-field detection level (voltage threshold for starting the gap servo), and the near-field detection level 8 is input to the system controller 20. The system controller 20 compares the input total reflected return light amount 24 with the near-field detection level 8 and outputs a predetermined control signal to the approach voltage generator 23 and the switch 26 based on the comparison result. Further, the approach voltage generation unit 23 outputs, for example, the step-like or ramp-like signal voltage, or the approach voltage 14 obtained by smoothing them with a low-pass filter (not shown). In this case, for example, it is preferable that the maximum value of the approach voltage is set to a voltage value at which the near-field detection level 8 is detected or a voltage value higher than that.

  The near field detection level 8 is set as shown in FIG. 7, for example. That is, the near-field detection level 8 is set to a value larger than the target value 7 of the gap servo in the near field region. For example, the near-field detection level 8 is set to 0.8 (V) in the linear region when the value of the total reflected return light amount 24 in the far field region is normalized to 1 (V). The gap servo target value 7 is set by the gap servo target value setting unit 22 (see FIG. 6). The gap servo target value 7 is set to a value smaller than 0.8 (V) within the linear region, for example, 0.5 (V).

  The system controller 20 compares the near-field detection level 8 with the total reflection return light amount (corresponding voltage value) 24. Based on the comparison result of the system controller 20, for example, when the total reflected return light amount 24 is larger than the near-field detection level 8, that is, when the SIL 2 is at the far field distance, the output signal 29 to the switch 26 of the system controller 20 becomes Low. . On the other hand, when the total reflected return light amount 24 is smaller than the near-field detection level 8, that is, when the end surface 2a of the SIL 2 is a near field distance, the output signal 29 becomes High. When the output signal 29 of the system controller 20 becomes High, the switch 26 is turned ON and the gap servo is started for the first time. The total reflected return light amount 24 is deviated by the gap servo target value 7 and input to the switch 26 as a deviation signal 25.

  The switch 26 outputs the deviation signal 25 as the servo voltage 27 when it is turned on as described above, that is, when there is a signal to start the gap servo. By such a gap servo, the gap between the end surface 2 a of the SIL 2 and the recording surface 47 a of the disk 47 is controlled so as to coincide with the gap servo target value 7.

  Note that as the total reflected return light amount, all of the light incident on the SIL 2 may be detected, or only a component of NA> 1 may be detected. Alternatively, a component having a polarization plane parallel to the incident light may be used as the gap error signal.

  Next, the tilt of the light condensing element 5 will be described. The tilt referred to here is a relative tilt between the recording surface 47a of the disk 47 and the end surface 2a of the SIL 2. As the tilt is closer to zero, an appropriate gap servo or an appropriate signal reproduction is performed. FIG. 8 is a graph showing the relationship between the tilt angle and the total reflected return light amount. From this graph, it can be seen that the relationship between the tilt angle and the total reflected return light amount is, for example, a quadratic function. The so-called initial tilt adjustment according to the present embodiment is an attempt to adjust the tilt using the relationship shown in this graph. In FIG. 8, the sign of the tilt angle indicates the direction of inclination of the end surface 2a of the SIL 2. For example, if the tilt in the state of the SIL 2 shown in FIG. 9A is defined as positive, the SIL 2 shown in FIG. The tilt in this state can be expressed negatively. In the graph of FIG. 8, a portion indicated by a symbol C indicates a state where the tilt is zero.

  FIG. 10 is a perspective view of the disk 47 and the light collecting element 5 for explaining the radial direction and tangential direction of the tilt. In this figure, when the X direction is the radial direction of the optical disc 47, the Y direction orthogonal to the X direction is the tangential direction. In this case, the tangential tilt is a tilt angle (Tt) around the X axis, and the radial tilt is a tilt angle (Tr) around the Y axis.

  Next, the operation in the stage before recording or reproducing a signal in the optical disc driving apparatus 1 will be described. More specifically, the cleaning operation, the initial tilt adjustment operation, the gap servo operation, and the like will be described in order. FIG. 11 is a flowchart showing the operation.

  When the disk 47 is loaded in the optical disk drive 1, the SIL 2 is cleaned by the lens cleaning mechanism 60 (step 1101). Specifically, for example, as shown in FIG. 12A, the SIL 2 located at a position away from the tape 61 comes into contact with the tape 61 as shown in FIG. Thereby, the dust adhering to the end surface 2a is removed. When the cleaning is finished, as shown in FIG. 12C, the SIL 2 is separated from the tape 61, and the cleaning operation of the SIL 2 is finished.

  FIG. 13A is a view showing a state in which the end surface 2a of the SIL 2 is clean. FIG. 13B is a diagram illustrating a state in which dust 69 is attached to the SIL end surface 2a. When dust is not attached, the total reflected return light amount becomes almost zero when the SIL end surface 2a is brought close to the recording surface 47a of the disk 47 as shown in FIG. . However, as shown in FIG. 13B, when dust 69 adheres to the SIL end surface 2a, the SIL 2 approaches the disk 47 as shown in FIGS. 14B and 14C. The total reflected return light quantity does not become zero. When viewed from the graph of the total reflected return light amount, it is as shown in FIG. That is, although the SIL 2 cannot approach the disk 47 any more, a return light amount of, for example, a normalization level of 0.4V is obtained. In this case, as shown in FIG. 15B, when the gap target value 7 is set lower than the contact voltage (0.4V) (in FIG. 7, the gap target value is set to 0.5V, for example). However, a voltage proportional to the gap cannot be obtained, the servo system becomes unstable, and oscillation occurs during gap servo (step 1103 described later). As shown in FIG. 15C, when the gap target value 7 is set above the contact voltage (0.4V), the gap servo is applied, but a voltage proportional to the gap is obtained. The gap maintained by the servo is unreliable.

  FIG. 16A shows a state in which the total reflected return light amount 24 is appropriate and the gap servo control is possible. The horizontal axis is time. This represents a clean state where there is no dust between the SIL 2 and the disk 47. FIG. 16B shows a state in which an appropriate total reflection return light amount cannot be obtained due to the influence of dust adhering to the SIL end surface 2a as described above.

  When the cleaning operation of SIL2 is completed, the light collecting element 5 is moved to a predetermined position in the radial direction of the disk 47 by a thread motor (not shown). The predetermined position may be the inner peripheral side or the outer peripheral side of the disk 47, and may be a position determined in advance for the initial tilt adjustment operation in the next step 1102. When the SIL 2 moves to the predetermined position in this way, the initial tilt is adjusted as follows (step 1102).

  FIG. 17 is a flowchart showing the initial tilt adjustment operation. In this operation, as will be described later, an approach voltage used in the gap servo operation is used to bring the SIL 2 closer to and in contact with the disk 47.

  First, the approach voltage to the near field is applied to the triaxial actuator 6 (step 1701). At this time, even if the approach voltage becomes the near-field detection level 8 (see FIG. 7), the switch 26 (see FIG. 4) should not be turned on. For example, the approach voltage in step 1701 may be set to a voltage of the total reflected return light amount level 7 corresponding to the gap target value or lower. The approach voltage set in this way is applied to the triaxial actuator 6 to bring the SIL 2 into contact with the disk 47 (step 1702). Tilt control can be performed without damaging the signal recording surface 47a of the disk 47 by setting the position on the disk 47 where the SIL 2 is in contact with the signal recording area 47a. During the tilt adjustment in step 1102, the disk 47 does not rotate and remains stationary.

  When SIL2 comes into contact with the disk 47, it is checked whether or not the total reflection return light amount is almost zero (step 1703). If the total reflected return light amount is almost zero, the SIL 2 and the disk 47 are in contact with each other without a tilt, that is, the gap is zero, so the total reflected return light amount is zero. However, even when the SIL 2 is in contact with the disk 47, when the tilt occurs as shown in FIG. 9A or 9B, the center of the SIL 2 that obtains the return light amount is obtained. The gap with the disk 47 does not become zero. Accordingly, the relationship between the gap and the total reflected return light amount when the SIL 2 is inclined is as shown in FIG. 18, and even if the gap is zero, the total reflected return light amount does not become zero. Therefore, when the gap is zero, that is, when the SIL 2 and the disk 47 are in contact with each other, it can be determined whether or not the SIL 2 is tilted by checking whether the total reflected return light amount becomes zero. Therefore, when the SIL 2 is tilted, the tilt of the SIL 2 is adjusted so that the total reflected return light amount becomes zero.

  Also, the lens cleaning in step 1101 before the tilt adjustment means that, as described above, the tilt adjustment is performed while obtaining an appropriate total reflected return light amount by bringing the SIL 2 and the disk 47 into contact with each other. It is very effective when considered. That is, when the lens is not cleaned and dust is attached to the SIL 2, proper tilt adjustment cannot be performed.

  In step 1703, if the total reflected return light amount is zero, SIL2 is not inclined with respect to the disk recording surface 47a, and there is no need to adjust the tilt of SIL2. Therefore, in this case, the approach voltage applied in step 1701 is returned to zero (step 1709), and is separated from the disk 47 of SIL2 and returned to the initial position in the far field. Alternatively, the applied voltage may be lowered to near the level of the gap target value 7 in the middle without returning to the initial position. Thereafter, the gap servo in step 1103 in FIG. 11, which will be described later, may be started.

  Returning to the description of FIG. If the total reflected return light amount is not substantially zero in step 1703, for example, first, adjustment is made so that the radial tilt is minimized among the two tilts (step 1704). This tilt adjustment is performed until the change rate of the total reflected return light amount becomes smaller than Δa (step 1705). Here, the rate of change of the total reflected return light amount is the ratio of the return light amount before and after the voltage is applied to the triaxial actuator 6 and the SIL 2 is tilted by a predetermined tilt angle. The slope of the curve at each tilt angle indicated by. If this inclination is zero, the tilt of SIL2 is zero (point C). This tilt adjustment will be described in more detail below.

  FIG. 19 is a flowchart showing specific operations of steps 1704 and 1705. First, the convergence parameter N is set to N = 0, and the movement gain k is set to k = 1 (step 1901). As shown in FIG. 20, the movement gain k is an angular amount per time when the SIL 2 is tilted by a predetermined tilt angle when the tilt of the SIL 2 is adjusted. On the graph of FIG. 8, the movement gain k is the movement amount on the horizontal axis. Actually, the movement gain k can also be expressed by a voltage applied to the tilt actuator. The convergence parameter N is the number of times (count value) that the polarity of SIL2 is reversed after passing through point C every time it passes through point C, as will be described later, when adjusting the tilt of SIL2. Here, the predetermined tilt angle may be any value of, for example, 0.1 ° to 10 °, but is not limited to this range and can be arbitrarily set.

  When the convergence parameter N and the movement gain k are set, the SIL 2 is inclined by a predetermined tilt angle with the movement gain k (step 1902). Here, since step 1704 in FIG. 17 has been described, it is assumed to be inclined in the radial direction, for example, in the direction of arrow A in FIGS. If SIL2 tilts in the A direction and the total reflected return light amount decreases (YES in step 1903), the total reflected return light amount is converged toward point C, so that the tilt adjustment direction is estimated to be correct, and next Go to step. If the total reflected return light amount increases (NO in step 1903), the polarity of the tilt control is reversed (step 1904), and the tilt angle is changed in the opposite B direction this time to adjust the tilt.

  If the total reflected return light quantity is decreased in step 1903, the SIL2 is further tilted in the A direction with the movement gain k (step 1905). If the total reflected return light quantity is decreased by this, the movement gain k is further moved in the A direction. Tilt adjustment is performed, and tilting is performed until the total reflected return light amount increases beyond point C. When the total reflected return light amount increases (YES in step 1906), the convergence parameter N is incremented by 1, and the movement gain k is multiplied by α (<1) to set a new convergence parameter N and movement gain k ( Step 1907). Thereafter, the polarity of the tilt direction of SIL2 is reversed (step 1908), and SIL2 is tilted in the B direction with the newly set movement gain k (step 1909). When the SIL2 is tilted in the B direction, if the total reflected return light amount decreases (NO in step 1910), it is estimated that the tilt adjustment direction is correct, and the movement gain k continues in the B direction. To tilt SIL2. On the other hand, if the total reflected return light amount has increased (YES in step 1910), since the point C has been passed, the convergence parameter N is further incremented by 1 and the movement gain is multiplied by α to newly It is set (step 1911) and the polarity in the moving direction is reversed (step 1912). When the convergence parameter N becomes N ≧ X (X can be arbitrarily set) (YES in step 1913), the tilt adjustment is finished. FIG. 21 shows how the total reflected return light amount changes due to the tilt adjustment as described above. In FIG. 21, the horizontal axis can also be viewed as the passage of time.

  In this way, if it is detected in step 1903 that the total reflected return light amount is decreased, that is, the rate of change in the total reflected return light amount is negative, in step 1905, the next reflected light amount is first inclined in the same direction. If the decrease or increase is detected, that is, whether the change rate of the total reflected return light amount is positive or negative, whether the tilt is tilted can be confirmed. As a result, the tilt can be converged in the direction of decreasing the tilt, and the tilt can be automatically controlled.

  Returning to the description of FIG. As described above, when the change rate of the total reflected return light amount becomes smaller than Δa in step 1705, the adjustment of the radial tilt is finished. In step 1705, as described above, for example, it can be estimated that the change rate of the total reflected return light amount is smaller than Δa when N ≧ X. Alternatively, the determination in step 1705 may be made by actually calculating the change rate of the total reflected return light amount, that is, the ratio between the immediately previous total reflected return light amount and the current total reflected return light amount.

  The tangential tilt is adjusted by a method similar to the radial tilt adjustment method described above (steps 1706 and 1707). Note that the radial tilt adjustment and the tangential tilt adjustment may be performed in the reverse order.

  Finally, it is determined whether the total reflected return light amount is Δc or less (step 1708). In this case, the determination is made by actually calculating the ratio between the immediately preceding total reflected return light amount and the current total reflected return light amount. The predetermined value Δa (or the predetermined value Δb at the time of tangential tilt adjustment) can be set to an arbitrary value, but substantially zero is a desirable value to converge the adjustment. Further, the predetermined value Δc in step 1708 is a value determined depending on the disk medium. Even if the gap is zero and the tilt is zero depending on the disk media, the total reflected return light amount is not always zero.

  If the total reflected return light quantity is equal to or smaller than the predetermined value Δc in step 1708, thereafter, the applied approach voltage is set to zero (step 1709), and SIL2 is separated from the disk 47, and SIL2 is set to the initial position.

  As described above, since the tilt adjustment is performed with the SIL 2 in contact with the disk 47, the tilt can be surely eliminated. Thereby, gap control can be appropriately performed thereafter.

  Returning to the description of FIG. When the tilt adjustment is completed as described above, gap servo is started (step 1103). Specifically, first, when the approach voltage 14 is applied by the approach voltage generator 23 and the near field detection level 8 is detected, the switch 26 is turned on and the deviation signal 25 is output to the triaxial actuator 6 as the servo voltage 27. Is done. Thus, the gap between the SIL end surface 2a and the disk recording surface 47a is controlled so as to coincide with the gap servo target value 7. There are various other methods for the gap servo. For example, the gap servo method disclosed in Patent Document 1 may be used.

  In this gap servo, the rotational speed of the disk is rotated at a relatively low rotational speed (step 1104). The number of rotations is lower than that during signal recording or reproduction. Specifically, it is 50-1000 rpm, 100-600 rpm, or 200-400 rpm. For example, since only SIL2 is cleaned, there is a possibility that dust is attached to the disk recording surface 47a. If the disk 47 rotates at a high speed with dust attached to the recording surface 47a, the SIL 2 may collide with the dust on the disk 47, and the SIL 2 may be damaged or destroyed. However, this embodiment can solve such a problem by rotating the disk 47 at a low speed.

  Considering this, it is possible to set so that the cleaning of both the SIL 2 and the disk 47 is performed before the tilt adjustment in Step 1102. However, for the time being, only one of them, for example, cleaning the SIL 2 and performing tilt adjustment and gap servo can shorten the time until signal recording or reproduction, compared to the case where both are cleaned.

  For example, when the gap servo is started, the gap error signal 24 (a signal indicating a change in time of the detection voltage value of the total reflected return light amount (see FIG. 7)) from the predetermined threshold Δ in the first rotation of the disk 47 It is determined whether it is smaller than N (step 1105). When dust is attached to the disk recording surface 47a, the gap error signal 24 is as shown in FIG. According to FIG. 22, the gap error signal 24 changes in an impulse shape at two locations in one rotation (indicated by reference sign D). This is a phenomenon that occurs because dust is present at two locations on the disk recording surface 47a, and the SIL 2 hits the dust at that location. Or, it means that the servo operates so that the SIL 2 does not collide with the disk 47. The magnitude of this impulse corresponds to the size of dust.

  Therefore, in step 1105, threshold values + Δ and −Δ are set as shown in FIG. 23, and a gap error exceeding the threshold values + Δ and −Δ is measured. In FIG. 23, for example, measurement is performed five times during one rotation. If the number of pulses during one rotation is smaller than the predetermined number N, it is determined that there is no particular problem, and the disk 47 rotates at a predetermined rotation number, for example, 60 Hz (step 1106). This N depends on the design and may be an arbitrary number. Further, the rotational speed of the disk 47 is not limited to 60 Hz, and may be larger or smaller than this, and may be the rotational speed at the time of signal recording or reproduction (including the rotational speed of the integer multiple speed). However, it is larger than the rotation speed in the above step 1104. This is because the purpose is to measure the gap error at the number of rotations during recording or reproduction as much as possible.

  When the gap error signal 24 is smaller than the predetermined threshold γ after reaching the predetermined disk rotation speed or while accelerating to the rotation speed (YES in step 1107), the disk 47 is approached. A signal is recorded or reproduced using the field light (step 1108). If this is not the case (NO in step 1107), that is, if the gap error signal 24 is as shown in FIG. Indicates that the servo cannot follow. In this case, the remaining error increases, and the possibility that the SIL end surface 2a collides with the disk increases. In this case, recording or reproduction is stopped.

  If the impulse generated in the gap error signal during one rotation of the disk is N times or more (NO in step 1105), the disk 47 may be contaminated, so the rotation of the disk 47 is stopped (step 1109). When the disk 47 is stopped, the disk recording surface 47a is cleaned by the disk cleaning mechanism 80 at a radial position on the disk 47 where at least SIL2 has been present (step 1110). Specifically, the cleaning member 82 moves upward and comes into contact with the disk recording surface 47a to rotate the disk 47 at least once. As described above, the cleaning member 82 of the disk cleaning mechanism 80 has a length about the radius of the disk 47. Therefore, for example, as shown in FIG. 25, the dust 69 can be removed simply by rotating the disk 47.

  When the dust 69 adhering to the disk 47 is removed, the rotation of the disk 47 is stopped and the SIL 2 is brought into contact with the recording surface 47a again (step 1111). When the voltage due to the total reflected return light amount at this time, that is, the voltage when the gap is estimated to be zero (hereinafter referred to as contact voltage) is larger than a predetermined voltage α as shown in FIG. (NO in step 1112), it is determined that a tilt has occurred between the disk and the SIL due to the dust colliding with the SIL. In this case, start again from lens cleaning.

  On the other hand, when the contact voltage is smaller than the predetermined voltage α as shown in FIG. 10, even if dust collides with SIL2, it is determined that there is no serious tilt between SIL2 and disk 47, and gap servo is performed. Start over.

  Steps 1105, 1107, 1112 and the like may be determined by, for example, a CPU (Central Processing Unit) (not shown) of the optical disc driving apparatus 1, the system controller 20, or the like.

  As described above, since the optical disk drive device 1 according to the present embodiment includes the contact-type lens cleaning mechanism 60 and the disk cleaning mechanism 80, dust is more easily removed than in the past. Thereby, gap servo control and initial tilt adjustment can be appropriately performed. In addition to these, of course, tracking servo control, tilt servo control, and the like can be appropriately performed.

  FIG. 27 is a plan view showing a part of a lens cleaning mechanism according to another embodiment. This lens cleaning mechanism is provided with a tape 161 that is sufficiently wider than the diameter of the SIL end surface 2a. In this case, the tape 161 is fixed, and the SIL 2 comes into contact with the tape 161 and moves, for example, in the tracking direction T or is cleaned while reciprocating. However, in addition to this, the tape 161 is not limited to being fixed, and may run in the direction of the arrow U.

  FIG. 28 is a plan view showing a part of a disk cleaning mechanism according to another embodiment. This disc cleaning mechanism is provided with a cleaning member 182 shorter than the radius of the disc 47. The length of the cleaning member 182 may be about 1/4 to 1/6 of the disk 47, for example. Further, the cleaning member 182 is configured to be movable in the radial direction (tracking direction) by a drive mechanism (not shown). Thus, for example, while the disk 47 is rotated, the cleaning member 182 moves in the tracking direction and contacts the disk recording surface 47a for cleaning.

  FIG. 29 is a flowchart showing a lens cleaning method according to another embodiment. The method shown in FIG. 29 may be used in the lens cleaning process in step 1101 shown in FIG. 11, but is not limited to this, and is merely an example of one of the lens cleaning methods. .

  It is assumed that the disk 47 is stationary during the lens cleaning. For example, as shown in FIG. 26, the total reflected return light amount when the SIL 2 is brought into contact with the disk 47 is compared with the threshold value α (step 2901). If the total reflected return light amount is smaller than α, it is determined that dust is not attached to the SIL 2, and the lens cleaning process is terminated. If the total reflected return light amount is larger than α, it is determined that dust is attached to the SIL 2 and a lens cleaning process is performed.

  For example, when a tape type as described above is used as the lens cleaning mechanism, when there is no remaining tape (NO in step 2902), the tape cleaner needs to be replaced (step 2903), and the cleaning process is performed. I will not. If there is a remaining tape in step 2902, as shown in FIG. 12B, the SIL end face 2a is pressed (step 2904), and the end face 2a is cleaned by running the tape (step 2905). . And as shown in FIG.12 (c), SIL2 leaves | separates from the tape 61, and a tape is moved a little after this. Thereby, when the SIL end surface 2a comes into contact with the tape next time, it can be brought into contact with a clean surface.

  Of course, the tape-type cleaning mechanism used in this cleaning method includes the form shown in FIG.

  FIG. 30 is a flowchart showing another example of a gap servo when, for example, the lens cleaning mechanism 60 is not used and only the disk cleaning mechanism 80 is used. The disk cleaning method here may be used in the disk cleaning process in step 1110 shown in FIG. 11, but is not limited to this, and an example is given as one of the disk cleaning methods. Not too much.

  First, the disk 47 is rotated in order to blow away the dust adhering to the disk recording surface 47a to some extent (step 3001). After rotating for a predetermined time, the cleaning member 82 contacts the disk recording surface 47a (step 3002). After the cleaning member 82 comes into contact, the disk is rotated N times (step 3003). N is determined experimentally, and N ≧ 1. After N rotations, the disk is stopped (step 3004), gap servo is started (step 3005), and after the gap between the SIL2 and the disk 47 reaches a predetermined gap, the disk is rotated (step 3006). Here, since the disk is not rotating at the time when the gap servo is started, the possibility that the SIL collides with the dust can be reduced even if the dust on the disk is not completely removed and remains. it can.

  After the gap servo is applied, a gap error signal is observed, and if an appropriate signal is obtained as shown in FIG. 16A (NO in step 3007), the signal is recorded or reproduced (step 3008). On the other hand, if the gap error signal is as shown in FIG. 22 (YES in step 3007), it is determined that dust is present, and the process is repeated from step 3002.

  The present invention is not limited to the embodiment described above, and various modifications are possible.

  For example, the initial tilt adjustment method is not limited to the method described with reference to FIGS. For example, the optical disk drive device 1 may include another laser light source and a photodetector for detecting the tilt angle in addition to the LD 31 shown in FIG. In this case, the initial tilt is adjusted based on the detection signal of the photodetector, or real-time tilt control is performed.

  In the above embodiment, both the lens cleaning mechanism 60 and the disk cleaning mechanism 80 are provided. However, the structure in which either one is provided may be sufficient. For example, when the disk 47 is a cartridge type, dust hardly adheres to the disk 47, so that only the lens cleaner needs to be provided. Alternatively, the lens cleaning mechanism 60 may not be provided, and only the disk cleaning mechanism 80 may be provided.

It is a figure which shows the structure of the optical disk drive device which concerns on one embodiment of this invention. It is the side view which showed the condensing element and the optical disk. It is a side view which shows a part of optical disk drive device. It is the top view seen from the lower side of the optical disk drive device 1 shown in FIG. It is a block diagram which shows the outline | summary of the said gap servo module. It is a block diagram which shows the detail of a data processing part. It is a graph which shows the relationship between a gap and the total reflected return light quantity. It is a graph which shows the relationship between a tilt angle and a total reflected return light quantity. It is a figure which shows the disc and condensing element for demonstrating a tilt, (a) defines positive tilt and (b) defines negative tilt. It is a perspective view of the disc and condensing element for explaining the direction of tilt. 5 is a flowchart showing operations such as cleaning, initial tilt adjustment, and gap servo. It is a figure which shows operation | movement of a tape cleaning mechanism in order. (A) is a state where the SIL end face is clean, and (b) is a view showing a state where dust is attached to the SIL end face. (A) is a figure which shows the case where SIL is in a normal state, (b) is the case where there is dust, (c) is the case where there is dust and there is tilt. It is a graph which shows the relationship between the gap in case dust exists, and a total reflected return light quantity, respectively. (A) is a graph which shows the state where a gap error signal (total reflection return light quantity) is normal, and (b) oscillates. It is a flowchart which shows operation | movement of initial tilt adjustment. It is a graph which shows a mode that a total reflected return light quantity does not become zero even if a gap is zero. It is a flowchart which shows the specific operation | movement of step 1704 and 1705 in FIG. It is a figure for demonstrating the direction of the inclination of SIL, and the movement gain k. It is a figure which shows the mode of the change of the total reflected return light quantity by tilt adjustment. It is a graph which shows a gap error signal when dust has adhered to the disc recording surface. FIG. 22 is a graph showing an example in which, for example, a pulse exceeding a threshold value is measured five times in one rotation of the disk. It is a graph which shows an example in case gap error signal 24 is larger than a predetermined threshold. It is a figure for demonstrating operation | movement of a disc cleaning mechanism. It is a graph which shows the case where the total reflected return light quantity is larger or smaller than a predetermined voltage α. It is a top view which shows a part of lens cleaning mechanism which concerns on other embodiment. It is a top view which shows a part of disc cleaning mechanism which concerns on other embodiment. It is a flowchart which shows the method of the lens cleaning which concerns on other embodiment. For example, it is a flowchart showing another example of the gap servo in the case where only the disk cleaning mechanism is used without using the lens cleaning mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical disk drive device 2 ... SIL
DESCRIPTION OF SYMBOLS 5 ... Condensing element 10 ... Data processing part 14 ... Approaching voltage 15, 27 ... Servo voltage 20 ... System controller 24 ... Total reflected return light quantity 31 ... Laser diode 40 ... Servo control system 47 ... Optical disk 47a ... Signal recording surface 51 ... Gap Servo module 53 ... tilt servo module 54 ... spindle servo module 60 ... lens cleaning mechanism 61, 161 ... tape 69 ... dust 80 ... disc cleaning mechanism 82, 182 ... cleaning member 182 ... cleaning member

Claims (3)

A light source that emits light;
A rotating mechanism for rotating a disk having a recording surface capable of recording a signal;
A light condensing element that is disposed opposite to the disk and capable of condensing the light emitted from the light source as near-field light on the recording surface of the rotating disk;
A contact-type cleaning mechanism for cleaning at least one of the recording surface and the condensing element in contact with the recording surface and the condensing element ;
Gap detecting means for detecting a gap between the light collecting element and the disk;
After at least one of the recording surface and the light condensing element is cleaned by the cleaning mechanism, a gap between the light condensing element and the rotating disk is made constant based on a detection signal from the gap detecting means. Gap control means for controlling,
The gap control means includes
First control means for controlling the gap while rotating the disk at a first rotation speed by the rotation mechanism;
And second control means for controlling the gap while rotating the disk at a second rotational speed higher than the first rotational speed after the control by the first control means,
The gap detection means detects the amount of light returned from the disk of the light emitted from the light source,
The first control means measures the number of times that the amount of return light exceeds a predetermined threshold while the disk rotates at least once, and if the measured number is less than the predetermined number of times threshold, the second control An optical disc driving apparatus for controlling to shift to the means . A light source that emits light;
A rotating mechanism for rotating a disk having a recording surface capable of recording a signal;
A light condensing element that is disposed opposite to the disk and capable of condensing the light emitted from the light source as near-field light on the recording surface of the rotating disk;
A contact-type cleaning mechanism for cleaning at least one of the recording surface and the condensing element in contact with the recording surface and the condensing element;
Gap detecting means for detecting a gap between the light collecting element and the disk;
After at least one of the recording surface and the light condensing element is cleaned by the cleaning mechanism, a gap between the light condensing element and the rotating disk is made constant based on a detection signal from the gap detecting means. Gap control means for controlling,
The gap control means includes
First control means for controlling the gap while rotating the disk at a first rotation speed by the rotation mechanism;
And second control means for controlling the gap while rotating the disk at a second rotational speed higher than the first rotational speed after the control by the first control means,
The gap detection means detects the amount of light returned from the disk of the light emitted from the light source,
The first control means measures the number of times that the amount of return light exceeds a predetermined threshold while the disk rotates at least once, and if the measured number is less than the predetermined number of times threshold, the second control An optical disc apparatus comprising: a recording / reproducing mechanism capable of at least one of recording the signal on the disc controlled to shift to the means and reproducing the recorded signal. Cleaning at least one of a recording surface of a disk capable of recording a signal and a condensing element that condenses light emitted from a light source as near-field light on the recording surface in a contact manner;
After the cleaning, rotating the disk;
Controlling the gap between the condensing element and the disk to be constant while rotating the disk ,
The step of controlling the gap comprises:
Detecting a gap (original claim 11) between the condensing element and the rotating disk by detecting a return light amount of the light emitted from the light source from the disk;
Controlling the gap based on the number of times the return light amount exceeds a predetermined threshold while the disk is rotating at least once while the disk is rotated at a first number of revolutions (original claim 13);
After the gap control at the first number of rotations, the recording surface is rotated as the disk at a second number of rotations higher than the first number of rotations, and the light is converted into near-field light based on the return light amount. And a method for driving the optical disc drive device, the method comprising controlling the light so that the light is condensed .

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