JP2004318929A - Optical head device and optical disk unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize stable driving control of an objective lens driver which constitutes an optical head device and has a driving mechanism with three shafts or more including the driving shafts in the focusing direction and the tracking direction. <P>SOLUTION: The objective lens driver 6 is provided with a movable part 7 which holds the objective lens 5 and is position-controlled in the focusing direction and the tracking direction with respect to a disk 2 is provided with a driving mechanism 9 for rotating the movable part 7 around the shaft with respect to a plane almost parallel with the disk 2, including the direction along a disk radial direction. By supplying a driving signal with a waveform obtained by combining a direct current voltage component or a low frequency alternating current component and high frequency alternating current voltage component to a driving coil constituting the driving mechanism 9, the influence of static friction in the driving mechanism 9 is relieved and an influence resulting from having a hysteresis characteristic in relation to a position and an angle corresponding to a driving voltage value is reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for stably controlling the drive of an objective lens used for beam irradiation on a disk-shaped recording medium.
[0002]
[Prior art]
2. Description of the Related Art In a disk drive device that performs signal recording and reproduction on an optical disk, an optical head device (so-called optical pickup) that irradiates a laser beam to the disk is provided, and a voice coil type actuator (so-called optical pickup) is used as an objective lens driving device. A two-axis actuator is used. That is, focus servo control for driving the objective lens held by the movable portion along a focus direction orthogonal to the recording surface of the disk, and moving the objective lens along a tracking direction parallel to the disk radial direction. Tracking servo control for operation is performed.
[0003]
By the way, in recent years, for the purpose of improving the followability of a laser beam spot on a recording track, in addition to the two-axis control in the focus direction and the tracking direction, the movable part can be tilted with respect to a plane parallel to the disk recording surface. For this reason, a device called a so-called three-axis actuator has been developed in which one-axis control is added so as to be able to cope with the surface runout of the rotating disk.
[0004]
For example, in a configuration in which a movable portion holding an objective lens is connected to a fixed portion via a support member (a leaf spring, a wire, or the like), a tilt (control) coil for tilting the movable portion with respect to the fixed portion. (For example, see Patent Literature 1) and a configuration in which a tilt coil is provided in a fixed portion and a field means (magnet) of the coil is provided in the movable portion.
[0005]
In a configuration in which the tilt coil is provided in the movable section (so-called moving coil type), for example, two support springs for supplying a drive current to each of the focus coil, tracking coil, and tilt coil of the movable section (A suspension member also serving as a power supply member) is required, and the movable portion is supported by the fixed portion via a total of six support springs.
[0006]
In a configuration in which a tilt magnet is provided in a movable portion (a so-called moving magnet type), a focus coil, a tracking coil, and a tilt coil are arranged in a fixed portion so as to face the magnet of the movable portion. Is supplied with a drive current via a power supply line.
[0007]
In an apparatus using such a three-axis actuator, for example, in a moving coil type configuration, it is necessary to add two support springs for supplying power to a tilt coil, which complicates the configuration and a structure for supporting a movable portion. The problem is the impact on the production and the increase in manufacturing costs. Also, the addition of a tilt coil to the movable section increases the weight of the movable section, resulting in a reduction in sensitivity, or the provision of three types of coils in the movable section, thereby reducing the size of the apparatus. In addition, there is a problem that thinning is hindered.
[0008]
On the other hand, in the moving magnet type configuration, the addition of the magnet to the movable portion increases the weight of the movable portion, resulting in a decrease in sensitivity, or requires the use of a magnet with a strong magnetic force or the supply of a large drive current, There are problems such as an increase in manufacturing cost and an increase in power consumption.
[0009]
In order to overcome such various problems, the applicant of the present application has disclosed in Japanese Patent Application No. 2003-14445 that a supporting block is connected to a movable block holding an objective lens by using a plurality of supporting springs. In addition, a tilt drive unit and a tilt magnetic circuit that constitute the support block are provided, and tilt drive is performed around a support shaft extending in a direction orthogonal to the focus direction and the tracking direction (radial skew direction of the movable block). A configuration in which the unit is rotated is proposed.
[0010]
[Patent Document 1]
JP 2000-149292 A
[0011]
[Problems to be solved by the invention]
However, in the conventional objective lens driving device having a tilt mechanism, the relationship between the DC drive voltage of the tilt coil and the tilt angle (the rotation angle around the support shaft) does not become a linear (linear) characteristic, and a hysteresis occurs. When having characteristics, there is a problem that this impairs the stability of control.
[0012]
FIG. 11 shows a state in which a DC drive voltage is supplied to the tilt coil, and the posture of the movable portion of the actuator (the It is an explanatory diagram in the case of controlling (a rotation angle is equivalent to a tilt angle.). The upper diagram (A) schematically shows the relationship between the drive voltage “V” applied to the coil on the horizontal axis and the tilt angle “α” on the vertical axis. FIG. 2B shows an example of a temporal change of the drive voltage “V”.
[0013]
(A) A graph line a shown by a solid line in the figure shows an ideal linear characteristic in which the drive voltage “V” and the tilt angle “α” have a proportional relationship. The characteristic has hysteresis as shown by a graph line b indicated by a one-dot chain line.
[0014]
Note that the drive voltage V shown in FIG. 6B indicates zero volts in the period (0), and the voltage “Vp” in the period (1) is one polarity voltage (a positive voltage, for example, a tilt angle in the positive direction). , And the voltage “Vn” in the period (2) indicates the other polarity voltage (a negative voltage, for example, a driving voltage corresponding to a negative tilt angle). In this example, the waveform changes after passing Vp from 0 and then reversing the polarity to Vn and returning to 0 as time elapses. In addition, positions corresponding to (0), (1), and (2) are added to the graph line b in FIG.
[0015]
It is required in the tilt angle control that the characteristic shown by the graph line b be made as close as possible to the characteristic shown by the graph line a.
[0016]
An object of the present invention is to realize stable drive control when an objective lens driving device constituting an optical head device has three or more drive mechanisms including drive axes in a focus direction and a tracking direction. I do.
[0017]
[Means for Solving the Problems]
The present invention has the following components in order to solve the above-mentioned problems.
[0018]
A movable part that holds the objective lens and is position-controlled in the focus direction and the tracking direction with respect to the disk-shaped recording medium, and a support mechanism therefor
[0019]
A drive mechanism for tilting the movable portion with respect to a plane substantially parallel to the disk-shaped recording medium, including a direction along the moving direction of the disk-shaped recording medium in the radial direction, or rotating the movable portion about an axis included in the plane;
[0020]
Drive control means for supplying a drive signal having a waveform obtained by combining a DC voltage component or a low-frequency AC component and a high-frequency AC voltage component to a drive coil constituting a drive mechanism.
[0021]
Therefore, according to the present invention, the influence of the static friction on the drive mechanism is reduced by using the drive voltage waveform obtained by combining the high-frequency AC voltage component with the DC voltage component or the low-frequency AC component, and the position and the angle with respect to the drive voltage value are reduced. It is possible to have a substantially proportional characteristic without hysteresis in a value relationship.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
SUMMARY OF THE INVENTION It is an object of the present invention to guarantee control stability by approaching ideal linear characteristics so that the relationship between the drive voltage and the control angle does not have hysteresis characteristics in drive control of an objective lens. In order to achieve this object, the present invention can cope with the control form relating to the driving coil. Therefore, the driving mechanism is not complicated, and the number of parts, the cost, and the like are not significantly increased.
[0023]
1 and 2 are schematic diagrams showing a basic configuration example of an optical disc device 1 according to the present invention. FIG. 1 shows a recording surface of a disc-shaped recording medium (hereinafter, simply referred to as a “disc”) 2. FIG. 2 is a side view as seen from a direction orthogonal to a plane including the rotation axis of the disk 2.
[0024]
The disk 2 is rotated by a rotating means 3 including a spindle motor (drive source) and its control circuit, and signal recording or signal reproduction of the disk 2 is performed using an optical head device 4. In the application of the present invention, the type of the disk 2 does not matter, and a read-only disk such as a compact disk (CD) or a recordable / reproducible disk such as a magneto-optical disk or a phase change disk is used. be able to.
[0025]
The optical head device 4 includes an objective lens driving device 6 having driving means for an objective lens 5 used for irradiating the disk 2 with a beam. A movable unit 7 holding the objective lens 5 is supported by a support mechanism. have. In applying the present invention, the configuration of the driving means of the objective lens 5 is not limited, but the following mechanism (the number in parentheses indicates a symbol) is provided as a driving mechanism of the movable unit 7. It is assumed that
[0026]
First and second drive mechanisms (8) for controlling the focus direction and the tracking direction
A third drive mechanism (9) such as a tilt mechanism;
[0027]
The first and second drive mechanisms 8 are known mechanisms configured by using drive coils (focus coils and tracking coils) and their field means (magnets and the like). It is necessary to control the position of the movable part 7 in the focus direction (see arrow “F” in FIG. 2) and the tracking direction (see arrow “T” in FIGS. 1 and 2). A moving mechanism (or a transport mechanism) 10 for moving the objective lens driving device 6 along the radial direction of the disk 2 (see the arrow “S” in FIG. 1) determines the visual field position of the objective lens 5 with respect to the disk 2. , And is distinguished from the drive mechanism 8.
[0028]
In the case of a voice coil type two-axis actuator constituting the objective lens driving device 6, focus servo control and tracking control are performed based on a signal read from the disk 2. In the above-described three-axis actuator, a further new A third drive mechanism 9 relating to the degree of freedom is added. For example, a mechanism for tilting the movable unit 7 with respect to a plane substantially parallel to the disk 2 including a direction along the movement direction of the moving mechanism 10 or rotating the movable unit 7 about an axis included in the plane. And a driving mechanism.
[0029]
In the example shown in FIG. 1, when viewed from the optical axis direction of the objective lens 5, the movable unit 7 is rotated around an axis “Ax” that extends through the center of the objective lens 5 in a direction perpendicular to the tracking direction. There is provided a mechanism for causing this to occur. In other words, the tilt angle described above is controlled in the rotation direction indicated by the arrow “α”, and the posture of the movable part 7 indicated by the solid line in FIG. 2 corresponds to the state (0), and the dashed line is based on this posture. As shown, the attitude of the movable part 7 rotated clockwise with respect to the Ax axis is in the state of (1), and the attitude of the movable part 7 rotated counterclockwise with respect to the Ax axis as shown by a two-dot chain line. Correspond to the state (2), respectively.
[0030]
In this example, the drive control in the rotation direction (radial skew direction) indicated by the arrow “α” is assumed. However, the present invention is not limited to this, and the rotation around the axis orthogonal to the axis “Ax” in the plane of FIG. The present invention can be applied to drive control in the moving direction (tangential skew direction) and the like, and is also effective in control of three or more axes.
[0031]
The third drive mechanism 9 includes a drive coil and a field means constituting the mechanism (details thereof will be described later in embodiments), and is controlled by a drive signal from the drive control means 11.
[0032]
Before describing the configuration of the drive control unit 11, a drive signal generated by the unit and supplied to the drive coil will be described.
[0033]
The control items related to the drive signal include a signal waveform, a frequency, a voltage (amplitude), a duration, and the like. First, the signal waveform will be described with reference to FIGS.
[0034]
The signal supplied to the driving coil is represented by a DC voltage component or a low-frequency AC component (hereinafter, referred to as a “base component”) indicated by “H” in the upper part of FIG. 3 and a “W” in the middle part of FIG. It is configured as a waveform (see the lower part of FIG. 3) obtained by combining the high-frequency AC voltage components shown in FIG. That is, by superimposing the high-frequency AC component on the base component of the drive voltage waveform shown in FIG. 3 (see “Te” in FIG. 3), it is possible to suppress the hysteresis characteristic which is a problem with only the base component.
[0035]
The signal waveform of the high-frequency component includes, for example, a sine wave, a rectangular wave, and a triangular wave.
[0036]
-Form using sine wave (see FIG. 4 (a))
-Form using a square wave (see FIG. 4 (b))
-Form using an attenuation wave (see FIGS. 4 (c) and 4 (d))
-The form which combined the above (refer FIG.4 (e)).
[0037]
First, in the example shown in FIG. 4A, the drive voltage “V” is a waveform in which a DC voltage component (see “H” in the figure) and a sinusoidal AC voltage component (see “W” in the figure) are combined. It is said. Employing this drive voltage waveform eliminates the effect of static friction on the parts of the drive mechanism where dynamic friction and static friction (static friction) are problematic, such as the sliding part between the support shaft and its bearing. By doing so, the angle (tilt angle) and attitude of the drive mechanism can be accurately controlled. Use of a sine wave is preferable in terms of reduction of power consumption required for control and simplification of the circuit configuration.However, in order to sufficiently eliminate the influence of static friction force and to guarantee stable operation control, a sine wave is used. Must be set to a certain level or more.
[0038]
Note that, depending on the configuration restrictions on the signal generating circuit having a waveform having a high-frequency AC component and the design conditions for servo control of the drive mechanism (such as the sensitivity of tilt servo control in an optical head device), the maximum allowable circuit is required. Even if a voltage (amplitude) signal is used, it may not be possible to obtain an effect sufficient to eliminate the influence of the static friction force. In such a case, a rectangular wave as shown in FIG. Is preferred. In other words, it is effective to increase the power supplied to the driving coil by using a rectangular wave including a harmonic component in order to reduce the influence of the hysteresis characteristic (that is, compared to a sine wave having the same amplitude value). Large motion is obtained, so that it can overcome the static friction force.)
[0039]
As a form using an attenuation wave, for example, an attenuation sine wave can be used as shown in FIG. 4C, or an attenuation rectangular wave can be used as shown in FIG. 4D. In other words, stable control is possible by gradually reducing the amplitude as time passes.
[0040]
In addition, various forms obtained by combining the above forms can be adopted according to the design conditions of the mechanism and the circuit. For example, in FIG. 4E, a case where a rectangular wave and a subsequent attenuated sine wave are used is shown. Is shown. That is, in the driving mechanism, the stability and control accuracy can be improved by giving a large motion using the rectangular wave at the initial stage and then switching to the damped sine wave.
[0041]
Also, in the case of using a sine wave, a rectangular wave, or the like, when the AC voltage is off (that is, when shifting to only the DC component), it is necessary to pay attention to its polarity. In other words, when the voltage polarity immediately before the off-state is not constant and becomes positive or negative with respect to the DC component, for example, the influence on the tilt angle value (the movable part has a certain angle). However, it is preferable to stabilize the control of the tilt angle by always defining the same polarity.
[0042]
FIG. 5 shows a main part of a configuration example relating to the drive control means 11, and shows a control circuit for controlling the tilt angle.
[0043]
The system controller 12 includes a microcomputer CPU (central processing unit) 13 for controlling the entire system, a memory 14, and a DAC (digital-analog converter) 15.
[0044]
The tilt detecting means 16 detects the relative attitude of the objective lens 5 and the movable part 7 with respect to the disk 2, that is, how much the optical axis of the objective lens 5 deviates from a state perpendicular to the disk surface. The detection signal is transmitted to the system controller 12 after being converted into a digital signal. The tilt detecting means 16 uses a skew sensor (such as a radial skew sensor) provided in the optical head device, and a read signal (a split type detector) by the optical head device without using such a dedicated sensor. Of detecting the amount of tilt using a difference signal of the amount of received light due to the above-mentioned method.
[0045]
The base component of the above-described drive voltage waveform is determined by the system controller 12 based on information based on a detection signal from the tilt detection unit 16. That is, the base component is calculated as a drive voltage component necessary to cancel the detected tilt angle, and the data indicating the result is stored in the memory 14 or sent directly to the CPU 13 so that the base component and the high-frequency component are This is used when generating a composite waveform with. Alternatively, a necessary drive voltage is stored in the memory 14 in advance, and a composite waveform is generated.
[0046]
Examples of the above-described waveform generating means for high-frequency components such as sine waves and rectangular waves include the following forms.
[0047]
(I) Form of generating signal waveform based on information stored in memory 14 in advance
(II) A form in which waveform data obtained as a result of calculation by the CPU 13 is used.
[0048]
First, as an example of the mode (I), as shown in FIG. 6, a method by referring to a table is mentioned, and an address “P + j” (j = 0, 1, 2,..., N−) starting from “P” By storing the voltage waveform data “Dj” of 1) as table data in the memory 14 and sending the data to the CPU 13 as necessary, a waveform of a high-frequency component can be generated. FIG. 6 illustrates a case in which a sine wave is used and a case in which a rectangular wave and an attenuated sine wave are used (the approximation is coarsened so that the number of points is intentionally reduced for easy viewing). Each point indicating the time-discrete data Dj is located on the sine wave at a predetermined time interval, and in the latter, the first half of each point indicating the discretized data Dj Are located on the square wave, and the remaining points are located on the damped sine wave. Note that these data Dj are subjected to interpolation processing by passing through the DAC 15.
[0049]
In the embodiment (II), for example, when a sine wave is used, the amplitude value is “A”, the angular frequency is “ω”, the time is “t”, and the high-frequency component “W” of the drive voltage is “W = A · sin (ω · t) ”can be obtained from the result executed by the CPU 13. In the case of a rectangular wave, it is sufficient to perform a process of repeating “+ A / 2” and “−A / 2” at regular time intervals. In the case of an attenuated sine wave, the exponential function is “exp (X)”, the attenuation coefficient is “η”, and the arithmetic expression “W = A · exp (−η · t) · sin (ω · t)” is used. good.
[0050]
A DAC 15 and a driver 18 are used as means for supplying a driving voltage having a waveform obtained by combining the base component and the high frequency component to the driving coil 17. That is, when the drive voltage to the drive coil 17 is described as “Y”, this means that the base component (H) read from the memory 14 and the high frequency component (W) generated by the above-described method are used by the CPU 13. The result is determined by combining by an addition operation (Y = H + W), and the result is sent to the driver 18 as an analog signal via the DAC 15, and a driving voltage is supplied to the driving coil 17 from the driver. After that, when a predetermined time elapses, when the high frequency component is made zero (W = 0), only the base component becomes (Y = H), and the drive mechanism (tilt mechanism) at this time causes the inclination of the disk surface to decrease. Obtained tilt angle values can be obtained (that is, at a position on the disk surface facing the objective lens, the optical axis of the objective lens is substantially orthogonal to the disk surface, and normal reading and writing of disk information can be performed. it can.).
[0051]
Note that the method is not limited to a method of performing digital operation processing of generation and synthesis related to a DC component and an AC component and then converting the analog signal to an analog signal. For example, digital operation processing of generation of a DC component and an AC component is performed. After that, a method of synthesizing each signal component converted into an analog signal, or providing an oscillation circuit such as a sine wave, or generating a signal related to a high frequency component using a divided output or a multiplied output of an existing clock signal. Various embodiments are possible, such as a method of performing.
[0052]
Next, the frequency of the high frequency component will be described with reference to FIG. FIG. 7 qualitatively illustrates a gain characteristic of a servo transfer function relating to the tilt mechanism as a Bode diagram.
[0053]
In the graph line 19 shown in the figure, “GL” indicates a constant gain in a low frequency band. At the primary resonance frequency indicated by “f0”, the gain “G” shows a peak, and the gain is equal to or higher than GL in the range indicated by “Δf” (see the hatched portion 20). Therefore, for example, when a sine wave is used as the high-frequency AC voltage, if the frequency is selected near “f0” even if the amplitude is the same, the gain G becomes larger (that is, a larger vibration displacement is obtained). ).
[0054]
This is effective not only in the case of using a sine wave but also in the case of using a rectangular wave or the like. The frequency of the high-frequency AC voltage component is preferably set to a value near the primary resonance frequency of the objective lens driving device.
[0055]
By the way, as described above, when a drive voltage waveform obtained by synthesizing a high frequency component such as a sine wave or a rectangular wave with respect to the base component is used, when adjusting or changing the tilt angle, by superimposing the high frequency component, It is preferable to minimize the influence on the tracking servo and the focus servo. For this purpose, a method of changing the tilt angle or the like in a state where the focus servo is applied without applying the tracking servo or in a state where both servos are not applied is exemplified. However, in this method, it may take a long time to read the signal from the disk while gradually changing the tilt angle value and to set the optimum angle value.
[0056]
Therefore, in order to minimize the influence on the tracking servo and the focus servo (reduce the influence on the servo error), a sine wave or an attenuated sine wave is used as a high-frequency component, and the amplitude or the maximum amplitude is set to a necessary minimum. It is preferable to set the limit value. Also, by shortening the time (duration or duration) in which the high-frequency component is superimposed on the base component, for example, even if the tracking error is slightly increased, the tilt angle value can be set before the tracking servo comes off. Can be completed, so that the influence on the servo can be reduced.
[0057]
By appropriately setting the waveform, frequency, amplitude, duration, etc. of the high-frequency component, it is possible to change the tilt angle in a short time while the tracking servo and focus servo are applied. It is.
[0058]
【Example】
8 to 10 show an embodiment according to the present invention.
[0059]
FIG. 8 shows a main part of a disk drive device 21, in which a disk 22 is rotated by a disk table 23 provided on a rotating shaft of a spindle motor.
[0060]
A moving mechanism (so-called thread mechanism) for moving the optical pickup along the radial direction of the disk 22 includes parallel guide shafts 24 and 25 and a linear driving mechanism (for example, a feed motor, a lead screw rotated by the motor, and a nut member. Used for controlling the positioning of the moving base 27 of the optical pickup 26.
[0061]
The movable base 27 has bearings 27a and 27b provided at both ends thereof slidably supported by guide shafts 24 and 25, respectively. In this example, a three-axis actuator constituting an objective lens driving device 28 Is installed.
[0062]
9 and 10 show a configuration example of the objective lens driving device 28. FIG. 9 is a perspective view, and FIG. 10 is a plan view showing the objective lens driving device 28 with a part cut away (viewed from the optical axis direction of the objective lens). .
[0063]
The objective lens driving device 28 has a support block 29 and a movable block 30 operated with respect to the support block 29.
[0064]
The support block 29 is provided with a tilt mechanism 9 </ b> A for rotating the movable block 30 around an axis orthogonal to the focus direction and the tracking direction as the third drive mechanism described above. It has a fixed portion 31 to be fixed, and a rotating portion 33 rotatably supported by the fixed portion 31 via a support shaft 32 (see FIG. 10).
[0065]
The fixing portion 31 is made of a magnetic material, and has a flat base portion 34, portions 35 and 35 bent at right angles from both ends in the longitudinal direction of the base portion 34, and a portion in the longitudinal direction of the base portion 34. And a support portion 36 bent at a right angle from one side edge of the central portion. The base portion 34 is fixed to the movable base 27, and tilt magnets 37, 37 are attached to the inner surfaces of the portions 35, 35, respectively, and the magnets are, for example, two-pole magnetized.
[0066]
The support portion 36 of the fixed portion 31 is provided with a support shaft 32 (see FIG. 10) for supporting the rotating portion 33, and its central axis extends in a direction orthogonal to the focus direction and the tracking direction. . The support shaft 32 is formed of, for example, a magnetic metal material such as stainless steel (SUS). On the outer peripheral surface, for example, annular protrusions 32a, 32a are formed at a predetermined distance in the axial direction. ing. The tip 32b of the support shaft 32 is formed in a hemispherical shape.
[0067]
The rotating portion 33 is formed in a substantially rectangular parallelepiped shape using a resin material such as a liquid crystal polymer, and a bearing member 38 of the support shaft 32 is provided at a central portion in the longitudinal direction. The shape of the bearing member 38 is a cylindrical shape with one end opened, a radial receiving portion 38a in which the projection 32a of the support shaft 32 is in contact with the inner surface, a thrust receiving portion 38b provided at the tip end, and an opening. The flange portion 38c provided in the portion is integrally formed using a polymer material (for example, polyamide, polyimide, polyphenylene sulfide, liquid crystal polymer, or the like). When the support shaft 32 is inserted into the bearing member 38, the protrusions 32a are slidably contacted with the inner surface of the radial receiving portion 38a, and the tip portion 32b is brought into contact (point contact) with the inner surface of the thrust receiving portion 38b. (To reduce friction).
[0068]
The rotating portion 33 is provided with a magnet 39 (see FIG. 9) in the vicinity of the bearing member 38, that is, in the central portion in the longitudinal direction, and utilizes a magnetic force acting between the magnet 39 and the support shaft 32. Thus, a stable rotation operation of the rotation unit 33 is guaranteed.
[0069]
Further, at both ends in the longitudinal direction of the rotating portion 33, tilt coils 40, 40 corresponding to the driving coil 17 described above are attached, and each coil faces the above-described tilt magnets 37, 37, respectively. State. The tilt coils 40, 40 are connected to a circuit section (see the driver 18 in FIG. 5) via a flexible printed wiring member 41, and the above-described drive voltage is applied. As shown in FIG. 10, magnetic portions 42, 42 made of a magnetic material such as iron are provided at the center of each coil. The rotating portion 33 is held at the neutral position by a magnetic force acting between the rotating portion 33 and the magnet 37. Further, center lines 37c, 37c extending in the longitudinal direction of the fixed portion 31 through the centers of the tilt magnets 37, 37, and central lines extending in the longitudinal direction of the rotating portion 33 through the centers of the magnetic portions 42, 42. The positions of 42c and 42c are shifted from each other, so that the rotating part 33 is attached to the fixed part 31 in the direction of arrow A shown in FIG. The bearing 32 is urged to ensure that the distal end 32b of the support shaft 32 is in contact with the inner surface of the thrust receiving portion 38b of the bearing member 38.
[0070]
Regarding a magnetic circuit formed by using the tilt coil 40 and the magnet 37, in the present embodiment, a driving coil is provided in the rotating portion 33 constituting the tilt mechanism 9A, and a field means (such as the magnet 37) for the coil is provided. Although the configuration (moving coil type) provided in the fixed portion 31 is shown, the invention is not limited to this, and a configuration in which a driving coil is provided in the fixed portion 31 and field means for the coil is provided in the rotating portion 33. Needless to say, a form (moving magnet type) may be adopted.
[0071]
The movable block 30 is supported by being connected to the rotating portion 33 using a support member (suspension member). In this example, the support spring is formed of a conductive elastic member (a leaf spring or the like). The support mechanism of the movable block 30 is constituted by using 43, 43,.
[0072]
The movable block 30 has a holding portion 45 for the objective lens 44 in a main body thereof, and has a coil bobbin 46 attached to the main body. The coil bobbin 46 is provided with a rectangular cylindrical focus coil winding portion 46a and tracking coil winding portions 46b, 46b, and coils wound around each winding portion (focus coil 47, tracking coil 48). , A driving current is supplied from a flexible printed wiring member 41 via support springs 43, 43,.
[0073]
A yoke piece 49 and a magnet 50 attached to the yoke piece 49 are arranged in a space (hollow portion) formed inside the coil bobbin 46, and a yoke piece 51 is provided between the coil bobbin 46 and the holding section 45. Are located. The magnet 50 and the yoke piece 51 face each other with the tracking coils 48, 48 therebetween. The yoke pieces 49 and 51 are connected to each other to form a U-shape, and the connecting portion between them is mounted on the movable base 27.
[0074]
When a drive current is supplied to the focus coil 47 and the tracking coils 48, 48, the movable block 30 is driven in a focus direction along the optical axis of the objective lens 44 and a tracking direction orthogonal to the direction, and a light source (not shown) The servo control is performed so that the light emitted from (1) is focused on the recording track on the disk through the objective lens 44.
[0075]
In the tilt mechanism 9A including the movable block 30, the support spring 43, the rotating portion 33, the fixed portion 31, and the like, when a driving current is supplied to the tilt coils 40, 40, the direction and magnitude of the current are increased. Then, an electromagnetic force corresponding to the direction and magnitude of the magnetic field generated by the tilt magnets 37, 37 is generated, and the turning portion 33 is turned around the support shaft 32 with respect to the fixed portion 31 by the moment, thereby being movable. The block 30 is rotated integrally. That is, the rotating portion 33 is supported by using the support shaft 32 and the bearing member 38, and a kinetic friction force and a static friction force are generated by sliding between the two. As described above, the high frequency component is superimposed on the base component. By supplying the drive voltage to the tilt coils 40, 40, the influence of the static friction force can be eliminated. Further, by selecting the frequency related to the high-frequency component to a value near the primary resonance frequency (f0), the voltage amplitude can be reduced. Since a large vibration displacement can be obtained even in a small case, a stable tilt operation without hysteresis can be performed with low power.
[0076]
When it is necessary to reduce the thickness of the tilt coil 40 (the width in the direction parallel to the optical axis of the objective lens 44) in order to reduce the size and thickness, a sinusoidal wave reduces the effect of static friction. When it is difficult to ensure the necessary driving force, it is preferable to use a rectangular wave or an attenuated rectangular wave.
[0077]
【The invention's effect】
As is apparent from the above description, according to the first and eighth aspects of the present invention, the stability of the objective lens drive control can be improved, and the performance and quality can be improved. In addition, since this can be dealt with by setting the drive voltage waveform, there is no accompanying problem such as a complicated drive mechanism and an accompanying increase in cost.
[0078]
According to the second aspect of the present invention, stable control can be realized when a drive mechanism having three or more axes including a drive mechanism in the focus direction and the tracking direction and a tilt mechanism is provided.
[0079]
According to the third aspect of the invention, the power consumption is small, the circuit configuration is easy, and the influence on the focus servo and the tracking servo can be reduced.
[0080]
According to the fourth aspect of the invention, by increasing the electric power supplied to the driving coil, a larger driving amount (angular displacement or the like) can be obtained.
[0081]
According to the fifth aspect of the present invention, it is effective to increase the stability of the drive control by gradually reducing the amplitude of the high-frequency voltage component and improve the controllability.
[0082]
According to the invention of claim 6, it is possible to enhance the accuracy of the drive control.
[0083]
According to the invention according to claim 7, even if the amplitude of the high-frequency voltage component is relatively small, a large drive amount can be obtained by setting the frequency, which is suitable for power saving and the like.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a basic configuration example of an optical disc device according to the present invention.
FIG. 2 is a diagram schematically illustrating the attitude of an objective lens and a movable unit with respect to a disk surface.
FIG. 3 is a diagram for explaining a drive voltage waveform related to a drive coil.
FIG. 4 is an explanatory diagram illustrating various aspects related to a high-frequency AC component.
FIG. 5 is a block diagram illustrating a control configuration example.
FIG. 6 is a diagram illustrating generation of a high-frequency component waveform.
FIG. 7 is a schematic graph for explaining a frequency of a high-frequency component.
8 shows an embodiment according to the present invention together with FIGS. 9 and 10, and is a diagram schematically showing a main part of a disk drive device. FIG.
FIG. 9 is a perspective view illustrating a configuration example of an objective lens driving device.
FIG. 10 is a plan view showing a configuration example of the objective lens driving device, with a part thereof being cut away.
FIG. 11 is a diagram for explaining a problem in control characteristics.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical disk device, 2 ... Disk-shaped recording medium, 4 ... Optical head device, 5 ... Objective lens, 6 ... Objective lens drive device, 7 ... Movable part, 9 ... Drive mechanism, 9A ... Tilt mechanism, 10 ... Moving mechanism, 11 drive control means, 17 driving coil, 28 objective lens driving device, 33 rotating section, 44 objective lens

Claims (8)

In an optical head device including an objective lens driving device used for beam irradiation on the disk-shaped recording medium and a moving mechanism for moving the objective lens driving device along the radial direction of the disk-shaped recording medium,
A movable portion that holds an objective lens and is position-controlled in a focus direction and a tracking direction with respect to the disk-shaped recording medium, and a supporting mechanism thereof,
A drive mechanism for inclining the movable portion with respect to a plane substantially parallel to the disk-shaped recording medium, including a direction along the movement direction of the moving mechanism, or rotating the movable portion around an axis included in the plane; An optical head device comprising: a drive control unit that supplies a drive signal having a waveform obtained by combining a DC voltage component or a low-frequency AC component and a high-frequency AC voltage component to a drive coil constituting a mechanism. . The optical head device according to claim 1,
The driving mechanism is a tilt mechanism for rotating the movable section around an axis orthogonal to a focus direction and a tracking direction, and the driving coil is attached to a rotating section connected to the movable section using a support member. Alternatively, an optical head device is provided with field means for the driving coil. The optical head device according to claim 1,
An optical head device using a sine wave as the high-frequency AC voltage component. The optical head device according to claim 1,
An optical head device using a rectangular wave as the high-frequency AC voltage component. The optical head device according to claim 1,
An optical head device using an attenuation wave as the high-frequency AC voltage component. The optical head device according to claim 1,
An optical head device using a rectangular wave and an attenuation wave following the rectangular wave as the high-frequency AC voltage component. The optical head device according to claim 1,
An optical head device, wherein a frequency of the high-frequency AC voltage component is set to a value near a primary resonance frequency of the objective lens driving device. In an optical disk device that performs signal recording or signal reproduction on a disk-shaped recording medium,
An objective lens driving device used for beam irradiation on the disc-shaped recording medium, and a moving mechanism for moving the objective lens driving device in a radial direction of the disc-shaped recording medium;
A movable portion that holds an objective lens and is position-controlled in a focus direction and a tracking direction with respect to the disk-shaped recording medium, and a supporting mechanism thereof,
A drive mechanism for inclining the movable portion with respect to a plane substantially parallel to the disk-shaped recording medium, including a direction along the movement direction of the movement mechanism, or rotating the movable portion around an axis included in the plane; An optical disc device comprising: a drive control unit that supplies a drive signal having a waveform obtained by combining a DC voltage component or a low-frequency AC component and a high-frequency AC voltage component to a drive coil constituting a mechanism. .

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