JP3906558B2 - Disk drive device and skew control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disk drive device capable of performing reproduction or recording operation corresponding to a disk-shaped recording medium.
[0002]
[Prior art]
In a disk drive device that can perform recording or reproduction with respect to a recording medium such as an optical disk or a magneto-optical disk, high-speed accessibility is required particularly when used as a computer peripheral device.
That is, it is preferable that a series of operations of seeking to a target address track according to a read command, a write command, etc., reaching the target address on the target track, and actually reading or writing can be performed as quickly as possible.
[0003]
[Problems to be solved by the invention]
By the way, in the disk drive device, if the optical axis of the laser beam irradiated to the disk from the optical head is tilted beyond a certain allowable range with respect to the recording surface of the disk, the data error rate deteriorates. And a skew servo mechanism for controlling the tilt state of the disk recording surface to an appropriate state.
When high speed access is required as described above, the skew servo operation is also required to be speeded up.
[0004]
However, when the disc is rotating, the disc runout becomes a tilting factor between the optical axis and the recording surface, that is, the normal skew servo will follow the disc runout. By following the surface runout as described above, the response becomes poor during high-speed seek, and it is difficult to realize a high-speed and stable skew servo.
In addition, following the surface deflection causes the skew mechanism (skew motor) to be driven frequently, which causes a problem of increased power consumption.
[0005]
[Means for Solving the Problems]
The present invention has been made in view of such problems, and an object thereof is to realize a high-speed and stable skew servo operation and to reduce power consumption.
[0006]
For this purpose, the skew control is performed so that the tilt state of the laser optical axis with respect to the disc-shaped recording medium is in an appropriate state. It is executed at the timing when the position becomes a specific position.
In other words, the disk runout affects the skew error signal as a signal of one rotation period. Depending on the ratio n to the normal rotation speed of the disk-shaped recording medium, the skew control by the skew servo means is executed once every n rotations. When the skew servo operation is executed at a timing at which the rotation angle position of the disk-shaped recording medium becomes a specific position, it becomes a skew servo operation that is not affected by the surface shake (does not follow the surface shake).
Further, not following the surface deflection leads to the unnecessary operation of the skew mechanism correspondingly.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
A disk drive device as an embodiment of the present invention will be described below.
First, with reference to FIG. 2, the structure of a disk reproduction drive portion (so-called mechanical deck portion) of the disk drive device of this example will be described.
This mechanical deck is constructed by providing various mechanisms necessary for reproducing the disk on the sub chassis main body 11. The loaded disk is loaded on the turntable 7, and the disk is rotated when the turntable 7 is driven to rotate by the spindle motor 6.
[0008]
In the pickup 1 having an optical system for irradiating a rotating disk with laser light and extracting information from the reflected light and a laser light source, the objective lens 2 serves as an output end of the laser light, as shown in the figure. Are arranged so as to face the disk.
[0009]
The pickup 1 is slidable in the disk radial direction by a so-called thread mechanism. For this reason, a main shaft 8 a and a sub shaft 12 are provided on both sides of the pickup 1. The main shaft 8a is inserted into the holder portion 8g of the pickup 1 and the sub shaft 12 is inserted into the holder portion 12g on the opposite side, so that the pickup 1 is supported by the main shaft 8a and the sub shaft 12, It is possible to move in the shaft direction.
[0010]
As a mechanism for moving the pickup 1 on the shaft, a thread motor 8b and thread transmission gears 8c, 8d, and 8e are provided, and a rack gear 8f is attached in the vicinity of the holder portion 8g of the pickup 1.
When the thread motor 8b is rotationally driven, the rotational force is transmitted to the thread transmission gears 8c, 8d, and 8e. Since the thread transmission gear 8e is meshed with the rack gear 8f, the transmitted rotational force moves the pickup 1 in the shaft direction 1. Therefore, the pickup 1 is moved in the shaft direction, that is, in the outer circumferential direction of the disk by the forward and reverse rotation of the thread motor 8b.
[0011]
The pickup 1 can be moved in the tilt direction so as to perform so-called skew correction in accordance with the tilt state of the loaded disc.
For this reason, one end of the main shaft 8a is gently held by the subchassis body 11 by the holding portion 8h, and the other end is fitted in the cam groove 15 formed in the skew gear 14.
The rotation operation of the skew motor 9 is transmitted to the skew gear 14 by the transmission gear 13.
[0012]
As shown in FIG. 3, the cam groove 15 in the skew gear 14 is formed in a U-shape that draws a spiral curve. If the distance from the rotation center of the skew gear 14 to the cam groove 15 is r, each part is formed. The distance is r1>r2>r3>r4>r5> r6.
Therefore, the camshaft 15 is supported in a state where one end of the main shaft 8a is fitted, whereby the inclined state of the main shaft 8a is set according to the rotational position state of the skew gear 14. That is, the inclination state of the pickup 1 in the radial direction can be adjusted by driving the skew motor 9.
[0013]
A skew sensor 10 is mounted on the pickup 1 in order to detect the relative tilt state of the laser optical axis from the pickup 1 and the disk. The skew sensor 10 detects the skew state by measuring the time until the output light is reflected by the disk and received, for example. If the skew motor 9 is driven based on the skew status detected by the skew sensor 10, the relative tilt status can be corrected by matching the tilt state of the pickup 1 with the loaded disc.
[0014]
FIG. 1 is a block diagram of the main part of the disk drive device of this example.
The disc 90 is loaded on the turntable 7 also shown in FIG. 2, and is driven to rotate at a constant linear velocity (CLV) or a constant angular velocity (CAV) by the spindle motor 1 during the reproducing operation. Then, the data recorded in the pit form on the disk 90 is read out by the pickup 1.
[0015]
Laser light from a laser diode 4 provided in the pickup 1 is output from the objective lens 2 to the recording surface of the disk 90 via an optical system (not shown). The objective lens 2 is held by a biaxial mechanism 3 so as to be movable in the tracking direction and the focus direction. Laser beam tracking and focus control are performed by the operation of the biaxial mechanism 3.
[0016]
The reflected light information of the laser light from the disk 90 is detected by the detector 5 through the optical system (not shown) from the objective lens 2 and is supplied to the RF amplifier 21 as an electric signal corresponding to the amount of received light.
[0017]
The RF amplifier 21 includes a current-voltage conversion circuit, an amplifier circuit, a matrix arithmetic circuit, and the like, and generates a necessary signal based on a signal from the detector 5. For example, an RF signal that is reproduction data, a focus error signal FE for servo control, a tracking error signal TE, a pull-in signal PI that is a so-called sum signal, and the like are generated.
[0018]
Various signals generated by the RF amplifier 21 are supplied to the binarization circuit 25 and the servo processor 31. That is, the reproduction RF signal from the RF amplifier 21 is supplied to the binarization circuit 25, and the focus error signal FE, tracking error signal TE, and pull-in signal PI are supplied to the servo processor 31.
[0019]
The reproduction RF signal obtained by the RF amplifier 21 is binarized by the binarization circuit 25, for example, an EFM signal (8-14 modulation signal; when the disc 90 is a CD disc) or an EFM + signal (8 -16 modulation signal; the disc 90 is a DVD disc) and is supplied to the decoder 26. The decoder 26 performs EFM demodulation, CIRC decoding, etc., and performs CD-ROM decoding, MPEG decoding, etc. as necessary to reproduce information read from the disk 90.
[0020]
The servo processor 31 generates various servo drive signals for focus, tracking, thread, and spindle from the focus error signal FE and tracking error signal TE from the RF amplifier 21 and the spindle error signal SPE from the decoder 26 or the system controller 30. Execute servo operation.
[0021]
That is, a focus drive signal and a tracking drive signal are generated according to the focus error signal FE and the tracking error signal TE and supplied to the biaxial driver 18. The biaxial driver 18 drives the biaxial mechanism 3 in the pickup 1. As a result, a tracking servo loop and a focus servo loop are formed by the pickup 1, the RF amplifier 21, the servo processor 31, and the biaxial driver 18.
[0022]
The servo processor 31 supplies the spindle motor driver 19 with a spindle drive signal generated based on the spindle error signal SPE. The spindle motor driver 19 applies, for example, a three-phase drive signal to the spindle motor 6 in accordance with the spindle drive signal, and causes the spindle motor 6 to perform CAV rotation or CLV rotation. In the case of CAV, the spindle error signal SPE can be obtained by comparing an FG pulse, which will be described later, with reference speed information. On the other hand, in the case of CLV, the spindle error signal SPE is generated by the decoder 26. It can be obtained by comparing the recovered clock with the reference speed information.
The servo processor 31 generates a spindle drive signal in response to the spindle kick / brake control signal from the system controller 30 and causes the spindle motor driver 19 to perform operations such as starting or stopping the spindle motor 6.
The spindle motor can be rotated at a high speed such as a double speed, a quadruple speed, or an eightfold speed when the normal speed is set to a single speed. Such speed setting is realized by the system controller 30 variably setting reference speed information to be compared with the spindle error signal SPE.
[0023]
The FG 27 generates a frequency pulse (FG pulse) corresponding to the rotation speed of the spindle motor 6 and supplies it to the servo processor 31. For example, six FG pulses are generated per one rotation of the spindle motor 6.
[0024]
The servo processor 31 generates a thread drive signal based on, for example, a thread error signal obtained from the tracking error signal TE, an access execution control from the system controller 30, and supplies the thread drive signal to the thread driver 17. The thread driver 17 drives the thread mechanism 8 according to the thread drive signal. The thread mechanism 8 indicates a part by the main shaft 8a, the thread motor 8c, the thread transmission gears 8c, 8d, 8e, etc. shown in FIG. 2, that is, the thread driver 17 drives the thread motor 8b according to the thread drive signal. By doing so, an appropriate slide movement of the pickup 1 is performed.
[0025]
The laser diode 4 in the pickup 1 is driven to emit laser light by a laser driver 20.
The servo processor 31 generates a laser drive signal for executing laser emission of the pickup 1 during reproduction or the like based on an instruction from the system controller 30 and supplies the laser drive signal to the laser driver 20.
[0026]
The servo processor 31 is also supplied with detection information from the skew sensor 10.
That is, the skew sensor 10 performs detection output as a current amount corresponding to the radial skew error amount of the disk 90 and the pickup 1, and the current signal is converted into a voltage signal by the I / V conversion unit, and then the differential amplifier. 23 is amplified and converted to digital data by the A / D converter 24.
This digital data becomes a so-called skew error signal SKE and is taken into the servo processor 31.
[0027]
The servo processor 31 supplies a skew drive signal to the skew driver 16 according to the skew error signal SKE, and drives the skew motor 9. Thus, the skew servo operation described in FIGS. 2 and 3 is realized.
In this example, the skew motor is a so-called stepping motor, and therefore the servo processor 31 generates a skew drive signal as a stepping drive.
[0028]
Various operations such as servo and decoding as described above are controlled by a system controller 30 formed by a microcomputer.
For example, operations such as playback start, end, and track access (seek) are realized by the system controller 30 controlling the operations of the servo processor 31 and the pickup 1.
[0029]
Hereinafter, skew control in such a disk drive apparatus will be described.
First, the skew error signal will be described with reference to FIG.
FIG. 4A shows the change of the skew error signal in the radial direction of the disk 90. As can be seen from this figure, the skew error signal appears as a DC component error in the radial direction.
On the other hand, FIGS. 4B and 4C show skew error signals in the circumferential direction at a certain radial position. For example, FIG. 4B shows the state of the skew error signal in the range of one round at the inner circumferential side position of the disk 90 (respective rotation angle positions A1 → B1 → C1 → D1 → A1), and FIG. The state of the skew error signal in the range of one round at the outer peripheral side position of the disk 90 (respective rotation angle positions A 2 → B 2 → C 2 → D 2 → A 2) is shown.
Thus, in one round, the skew error signal appears as an AC component error due to the influence of the so-called surface deflection of the disk 90.
[0030]
Therefore, when the actual skew error signal is continuously viewed, the AC component as shown in FIGS. 4B and 4C is superimposed on the DC component in FIG. The fact that the skew servo follows the AC component of one rotation period means that servo instability occurs and quick servo control cannot be performed.
Here, in this example, the timing is one interval per rotation of the disk 90 and the rotation angle position of the disk 90 becomes a specific position (for example, a position corresponding to the radial direction as A1... A2 = specified The skew control is executed only at the rotation angle position).
That is, if the skew control is performed only at the timing at which a specific rotation angle position is located on the circumference, servo control that is not affected by the AC component generated in one rotation can be executed.
[0031]
FIG. 5 shows operation waveforms of such skew servo operation.
FIG. 5A shows an FG pulse generated by the FG 27, and the 6 pulse period corresponds to one rotation period (one cycle) of the spindle motor 6.
In this one cycle, an AC component appears as the skew error signal SKE as shown in FIG.
Such a skew error signal SKE is taken in at the rising and falling timings of the FG pulse as an interrupt process as shown in FIG. Therefore, the skew error signal SKE is fetched 12 times in one cycle.
Then, the average value of the skew error signal SKE fetched 12 times is obtained, and skew drive is performed once per cycle as shown in FIG. Therefore, the skew servo of this example is executed based on the DC component of the skew error signal.
[0032]
FIG. 6 shows an interrupt process (process of the servo processor 31) for skew servo control.
The processing in FIG. 6 is executed at every interrupt processing timing in FIG.
Further, variables used in the processing include the cumulative value sksum of the skew error signal SKE, the count value fgC of the FG pulse, the average value skavg of the skew error signal SKE, and the fixed value has a window as an appropriate skew error range. The set upper limit value WH and lower limit value WL are used. The upper limit value WH and the lower limit value WL are set in advance based on the jitter best point and the like.
[0033]
When the interrupt process is started, first, in step F101, the skew error signal SKE is captured at that time, and the skew error signal SKE is added to the cumulative value sksum.
As described with reference to FIG. 5, the interrupt process is executed at the rising and falling timings of the FG pulse. In step F101, the count value fgC of the FG pulse is incremented.
[0034]
In step F102, it is determined whether or not the count value fgC = 12, and if the count value fgC = 12, one interrupt process is finished.
[0035]
At the time when the twelfth interrupt processing is performed, that is, at the timing of one rotation of the disk, the count value fgC = 12 in step F102, and the process proceeds to step F103.
At this time, the cumulative value sksum is the total value of the 12-sample skew error signal SKE. That is, it is the total value of the skew error signal SKE obtained during one rotation of the disk. Therefore, in step F103, the cumulative value sksum is divided by 12 to obtain the average value skvg. The average value skavg is a DC component of the skew error signal SKE in one rotation period.
In step F104, the cumulative value sksum and the count value fgC are cleared.
[0036]
In step F105, the average value skavg is compared with the upper limit value WH. When the average value skavg exceeds the upper limit value WH, it is determined that the skew error is large in the forward direction. Therefore, the process proceeds to step F106, and the skew motor 9 is driven in the reverse direction by one step. That is, as shown in FIG. 5C, the skew motor 9 is driven at a timing once per rotation.
In step F110, the conversion process by the A / D converter 24 is started for the subsequent interrupt process, and the interrupt process ends.
The reason why the A / D conversion process is started at this time is to avoid an increase in processing load due to the A / D conversion process being performed at the start of the interrupt process.
[0037]
On the other hand, if it is determined in step F105 that the average value skavg does not exceed the upper limit value WH at the time of a certain interrupt process, the average value skavg is compared with the lower limit value WL in step F107. When the average value skavg is lower than the lower limit value WL, it is determined that the skew error is large in the reverse direction, so the process proceeds to step F108 and the skew motor 9 is driven one step in the forward direction. That is, as shown in FIG. 5C, the skew motor 9 is driven at a timing once per rotation.
In step F110, the conversion process by the A / D converter 24 is started for the subsequent interrupt process, and the interrupt process is completed.
[0038]
Further, if a negative result is obtained in both steps F105 and F107 at the time of a certain interrupt process, that is, if the lower limit value WL ≦ the average value skav ≦ the upper limit value WH, the skew error is within the appropriate range at that time. It is judged.
For this reason, the power supply to the skew motor 9 is turned off in step F109. In step F110, the conversion process by the A / D converter 24 is started for the subsequent interrupt process, and the interrupt process is completed.
[0039]
By the processing as described above, in this example, the skew control is executed at an interval of one rotation of the disk 90 and at the timing when the rotation angle position of the disk 90 becomes the specific position.
As a result, the skew control does not follow the AC component due to the surface vibration of the disk 90, and an appropriate servo operation that follows only the DC component corresponding to the radial position is realized. This stabilizes the skew servo and prevents the servo from being delayed due to the influence of the AC component of the skew error signal SKE. Further, not following the AC component also means that unnecessary skew drive is eliminated, so that advantages such as reduction of power consumption and reduction of heat generation of the motor can be obtained, and this also increases the durability of the servo mechanism. Be improved.
Further, in this example, as shown in step F109, the skew motor 9 is turned off during the period in which the skew state is in an appropriate state, so that further reduction of power consumption and suppression of heat generation are realized.
[0040]
By the way, especially when a disk drive device is used as a computer peripheral device, the rotational speed of the disk 90 is often set to 2 × speed, 4 × speed, 8 × speed, etc. in order to improve the transfer rate.
In the processing example of FIG. 6 described above, skew control is performed once per rotation of the disk. However, when the rotational speed is increased, the skew control performed once per rotation is controlled in terms of time. If the interval becomes too short, there is a possibility that the skew motor 9 may be out of step or unable to follow at high speed in some cases.
FIG. 7 shows an example of processing suitable for the disk drive device that supports high-speed rotation.
[0041]
FIG. 7 shows an interrupt process for skew control as in FIG. 6, and step F201 adds the skew error signal SKE to the accumulated value sksum and increments the count value fgC as in step F101 of FIG. It is carried out.
In step F202, a variable RN is set according to the rotational speed of the spindle motor 6 at that time.
The variable RN is set to a value corresponding to the rotation speed as shown in FIG. As an example, an apparatus in which the spindle motor 6 is capable of rotating at 1 × speed, 2 × speed, 4 × speed, and 8 × speed will be described. For normal rotation speed, the variable RN = 12, and for 2 speed, the variable RN = The variable RN = 48 for 24 or 4 × speed, and the variable RN = 96 for 8 × speed.
[0042]
In step F203, it is determined whether or not the count value fgC = variable RN. If the count value fgC = variable RN is not satisfied, the interrupt process is terminated.
When the count value fgC = variable RN, the process proceeds to step F204. At this time, since the cumulative value sksum is the total value of the skew error signal SKE of RN samples, the cumulative value sksum is divided by the variable RN to obtain the average value skvg.
The processing after Step F205 is the same as the processing after Step F104 in FIG.
[0043]
That is, in the example of FIG. 7, skew control is performed once every rotation for normal rotation speed, but once for 2 rotations, once for 2 rotations, once for 4 rotations, once for 4 rotations, 8 times rotation. In this case, the skew control is performed at an interval of once every eight revolutions, and therefore the skew operation is appropriately executed even if the rotational speed is increased.
It should be noted that even when the speed is increased, such as 16 times speed or 32 times speed, the variable RN may be set accordingly and the skew control may be performed at an appropriate time interval.
[0044]
By the way, the example in which the setting of the variable RN is performed in the interrupt process of FIG. 7 has been given. Of course, the variable RN is not performed in the interrupt process, but the servo is performed when the system controller 30 sets the speed of the spindle motor 6. It may be performed in other processes such as setting the value of the variable RN in the processor 31.
[0045]
Further, when the spindle motor 6 is rotationally driven by the CLV method, the rotational speed is continuously changed. However, the calculation based on the rotational speed (or the address indicating the radial position) at that time or The variable RN may be set using a memory table.
That is, when driven at x-speed CLV, the variable RN changes on the inner and outer circumferences of the disk, and the time interval for executing the skew control is substantially constant (or within an allowable range in which the skew motor 9 does not step out). It is what.
[0046]
Although examples as various embodiments have been described above, it is needless to say that the present invention can be further modified in various ways.
For example, in each of the above examples, the skew error signal SKE is captured at the FG pulse timing, and a DC component is obtained by taking the average thereof. However, the skew error signal SKE is also captured at an interval of once per rotation, for example. You may do it. However, a more accurate DC component can be obtained by setting the average value as described above.
[0047]
In each of the above examples, the skew motor 9 is driven in steps F106 and F108 (F207 and F209) in units of one step of the stepping motor. The number of steps may be driven. For example, when the amount of skew error is large in the reverse direction, a plurality of steps are driven in the forward direction.
Then, a skew servo system with high responsiveness can be constructed.
[0048]
In the above example, the skew servo mechanism for the radial skew has been described. However, the present invention can be similarly applied to the skew servo mechanism for the tangential skew.
[0049]
【The invention's effect】
As described above, in the present invention, the skew control that makes the tilting state of the head mechanism relative to the disk-shaped recording medium an appropriate state is performed once every n rotations of the disk-shaped recording medium, and the disk-shaped recording is performed. This is executed at the timing when the rotation position of the medium becomes the specific position. Therefore, the skew servo operation does not follow the surface deflection of the disk, and only follows the DC component as radial skew or tangential skew, thereby realizing high-speed and stable skew servo control. There is. Such a skew servo operation is also suitable for a disk drive device that requires high-speed access.
In addition, the skew servo operation that does not follow surface deflection eliminates unnecessary operation of the skew mechanism, promotes power savings, and suppresses heat generation of the skew motor, improving the durability of the mechanism. There is also an advantage of doing.
[0050]
In the present invention, the interval for executing the skew control is variably set, for example, once every rotation, once every two rotations, etc., according to the rotational speed of the disk-shaped recording medium. That is, according to the rotation speed, the control execution interval can be set according to the tracking performance of the skew servo mechanism. For example, it is possible to prevent a situation in which the skew servo mechanism cannot follow when the rotation speed is very high. it can. That is, a stable skew servo mechanism can be realized even when the disk rotation speed is increased.
[Brief description of the drawings]
FIG. 1 is a block diagram of a disk drive device according to an embodiment of the present invention.
FIG. 2 is a perspective view of a mechanical deck of the disk drive device according to the embodiment.
FIG. 3 is an explanatory diagram of a skew adjustment mechanism of the disk drive device according to the embodiment.
FIG. 4 is an explanatory diagram of a skew error signal according to the embodiment.
FIG. 5 is an explanatory diagram of skew servo operation timing according to the embodiment;
FIG. 6 is a flowchart of an interrupt process for skew control according to the embodiment;
FIG. 7 is a flowchart of another skew control interrupt process according to the embodiment;
FIG. 8 is an explanatory diagram of a control interval variably set in another skew control interrupt process according to the embodiment;
[Explanation of symbols]
1 pickup, 2 objective lens, 3 biaxial mechanism, 4 laser diode, 5 detector, 6 spindle motor, 7 turntable, 8 thread mechanism, 9 skew motor, 10 skew sensor, 20 laser driver, 21 RF amplifier, 22 I / V Conversion unit, 23 differential amplifier, 24 A / D converter, 25 binarization circuit, 26 decoder, 27 FG, 30 system controller, 31 servo processor, 90 disks

Claims (2)

Rotation drive means for rotating the disk recording medium;
Skew error generating means for detecting a tilt state of the laser optical axis from the optical head mechanism with respect to the disk-shaped recording medium and generating a skew error signal;
Based on a skew error signal supplied from the skew error generating means, skew servo means for performing skew control so that the tilt state of the laser optical axis with respect to the disk-shaped recording medium is in an appropriate state;
Skew control by the skew servo means is executed at an interval of once every n rotations of the disk-shaped recording medium rotated by the rotation driving means and at a timing when the rotation angle position of the disk-shaped recording medium becomes a specific position. Control means;
Equipped with a,
The control means variably sets the interval of skew control by the skew servo means so as to be executed once every n rotations in accordance with a ratio n to the normal rotation speed of the rotation drive means. Drive device. The skew control is performed so that the tilt state of the laser optical axis from the optical head mechanism with respect to the disk-shaped recording medium is in an appropriate state. The skew control is performed once every n rotations of the disk-shaped recording medium, and the disk-shaped recording medium is rotated. At the timing when the angular position becomes a specific position ,
A skew control method characterized in that the interval of skew control by the skew servo means is variably set so as to be executed once every n rotations in accordance with a ratio n to the normal rotation speed of the disk-shaped recording medium .

Images