JP3769888B2 - Disk drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disk drive device capable of performing stable tracking servo control for areas of a plurality of types of disk-shaped recording media.
[0002]
[Prior art]
CD (compact disc) is widely used as an optical disc recording medium, and CD-type discs are used in various fields including music applications. Music CDs are usually read-only media, but write-once discs called CD-Rs (compact discs-recordables) have also been developed.
[0003]
On the other hand, a disc called DVD (Digital Versatile Disc / Digital Video Disc) has been developed as an optical disc recording medium suitable for multimedia use. It has been proposed that the DVD is applicable in a wide range of fields such as video data, audio data, and computer data. Further, although the DVD is a disk (diameter: 12 cm) having the same size as the CD, the recording capacity has been remarkably increased due to the reduction in the pitch of the recording track and the data compression technique. For this DVD, types such as a read-only DVD-ROM, a DVD-R that can be written only once, and a DVD-RAM that can be rewritten any number of times have been proposed.
[0004]
In a disk drive apparatus capable of recording / reproducing such various disk-shaped recording media, in order to control the tracking of the light spot, the reflected light with respect to the track guide information such as pit rows and grooves formed on the disk Are provided with a biaxial mechanism for driving the objective lens of the optical head by a tracking error signal obtained from the above and a sled mechanism for displacing the relative position of the entire optical head and the disk surface in the disk radial direction.
[0005]
As a light spot tracking control method, a three-spot method and a push-pull method are well known.
However, the three-spot method requires two side spots for detecting the tracking error signal separately from the main spot for detecting the main data of the disc, so that the optical system becomes complicated and a grating is required. There was a drawback of becoming.
[0006]
The push-pull method for generating a tracking error signal from the difference in intensity distribution between the left and right light spots has the advantage that an optical system can be configured with one spot as compared with the three-spot method. Since the offset voltage is generated in the push-pull signal when the lens is shifted, there is a drawback that a device for removing the offset voltage is required.
[0007]
Therefore, a phase difference method and a heterodyne method are known as tracking control methods that do not have the above-described drawbacks.
In the phase difference method, for example, the sum signal (A + C) of the detection units A and C positioned at the diagonal of the quadrant detector 21 including the detection units A, B, C, and D as shown in FIG. The tracking error signal is obtained by the phase difference from the sum signal (B + D). The details are disclosed in Japanese Patent Publication No. 2-56734.
[0008]
The heterodyne method, which is a kind of phase difference method, is, for example, a zero cross at the rise and fall of the sum signal (A + B + C + D) of the detectors A, B, C, and D of the detector 21 and the difference signal (A + C) − (B + D). A tracking error signal is obtained from a sampling pulse signal obtained by detecting a point. The details are disclosed in Japanese Patent Publication No. 2-21056.
[0009]
However, in the phase difference method and the heterodyne method as described above, when the depth of the pit formed as the track guide information on the disc is not an integral multiple of a quarter wavelength (λ / 4) as described later, There is a shift in the phase of the intensity signal of the far-field image projected between the detectors A and B and the detectors C and D of the detector 21. When the objective lens of the optical head unit moves in the radial direction of the track, for example, for tracking operation in a state where the phase is shifted as described above, between the detection units A and D of the detector 21 and the detection units B and C, That is, the light intensity in the radial direction of the detector 21 becomes unbalanced.
[0010]
For this reason, when a tracking error signal is generated by the phase difference method or the heterodyne method, an offset voltage is included in the tracking error signal in a disc whose pit depth is not an integral multiple of a quarter wavelength, and such an offset voltage is included. There is a drawback that stable tracking servo control cannot be performed with the tracking error signal.
[0011]
Here, the depth of pits formed on a ROM disk or the like will be described.
Usually, the pit represents a resist portion irradiated with a laser in the manufacturing process of the disc, and is viewed from the reading side of the disc (that is, the light source side, the light incident side) as shown in FIG. The closest is the pit. Therefore, the depth of the pit described in this specification is defined with the reading side as a plus.
[0012]
Similarly, a disk formed with a guide groove such as a RAM disk as shown in FIG. 13 is a groove closer to the reading side as viewed from the reading side, and the depth of the groove is defined with the reading side as a plus. ing.
[0013]
Therefore, for example, in the case of a bonded ROM disk as shown in FIG. 14, the pit depth of the A-side ROM disk close to the reading side is positive, and the pit depth of the B-side ROM disk far from the reading side. Is negative.
[0014]
In the following description, π (π = λ / 2) is used instead of the wavelength unit λ as a unit representing the pit depth. Therefore, the pit depth of the B-side disk of the bonded ROM disk in which the pit depth is 1/6 wavelength as shown in FIG. 14 is expressed as -π / 3.
[0015]
Next, FIG. 15 shows the relationship between the depth of pits formed on the disk and the phase difference generated between the detection units A and B on the upstream side of the detector 21 and the detection units C and D on the downstream side. To explain. As shown in FIG. 2, the upstream side or downstream side of the detector 21 is a position with respect to the rotation direction of the disc, and therefore the upstream side of the detector 21 is the reproduction progress direction of the disc.
[0016]
FIGS. 15A and 15B are diagrams showing the relationship between the depth of the pits and grooves formed on the disc and the phase difference.
As shown in FIG. 15 (a), it is generated between the depth of the pit formed on the disc and the output signals of the detectors A and B on the upstream side of the detector 21 and the output signals of the detectors C and D on the downstream side. The phase difference is a signal having a waveform such that the pit depth is synchronized with a period of ½ wavelength (π).
Further, as shown in FIG. 15 (b), between the depth of the groove formed on the disk and the output signals of the detection units A and B on the upstream side of the detector 21 and the output signals of the detection units C and D on the downstream side. The phase difference generated in the waveform is also a signal having a waveform such that the groove depth is synchronized with a period of ½ wavelength (π).
[0017]
However, as can be seen from FIGS. 15A and 15B, the phase difference caused by the pit depth and the phase difference caused by the groove depth are those in which the phase advance (delay) characteristics are reversed. .
[0018]
Therefore, in the case of a disc in which the pit (groove) depth formed on the disc is deeper than ½ wavelength (π), an amount obtained by subtracting an integral multiple of π from the physical depth of the pit (groove) It can be handled as the depth of the pit (groove). That is, for example, as shown in FIG. 15A, when the physical depth of the pit formed on the disk is 1.4π (shown as A in the figure), the pit depth is This physical pit depth (1.4π) can be handled as 0.4π (shown as A ′ in the figure), which is an amount obtained by subtracting π.
Therefore, the depth of the pit (groove) in the following description does not indicate the depth of the physical pit (groove) but subtracts an integer multiple of π from the depth of the physical pit (groove). It shall indicate the depth of the pit.
[0019]
As shown in FIG. 15 (a), when the depth of the pit formed on the disk is an integral multiple of a quarter wavelength (π / 2), the detectors A and B positioned upstream of the detector 21 The phases of the output signal and the output signals of the detection units C and D located on the downstream side coincide with each other, and no phase difference occurs.
[0020]
However, when the depth of the pit becomes shallower than π / 2, the phase of the output signal of the upstream detection units A and B advances relative to the phase of the output signal of the downstream detection units C and D, and the pit depth When π / 4 is reached, the phase advance of the output signals of the upstream detection units A and B is maximized. Thereafter, as the pit depth becomes shallower, the phase advance of the output signals of the upstream detection units A and B becomes smaller, and when the pit depth becomes zero, the upstream detection units A and B and the downstream detection units A and B The phases of the output signals of the detectors C and D again match.
[0021]
On the other hand, when the pit depth becomes deeper than π / 2, the phase of the output signals of the upstream detection units A and B is delayed with respect to the phase of the output signal of the downstream detection units C and D, and the pit depth Is 3π / 4, the phase delay of the output signals of the upstream detection units A and B becomes the maximum. Thereafter, as the pit depth increases, the phase lag of the output signals of the upstream detection units A and B decreases, and when the pit depth reaches π, the upstream detection units A and B and the downstream detection units A and B The phases of the output signals of the detectors C and D again match.
[0022]
In other words, when the depth of the pit becomes deeper than π / 2, the phase of the output signals of the downstream detection units C and D advances relative to the phase of the output signal of the upstream detection units A and B, and the pit depth When the length becomes 3π / 4, the phase advance of the output signals of the downstream detection units C and D becomes maximum. Thereafter, as the pit depth increases, the phase advance of the output signals of the downstream detection units C and D decreases, and when the pit depth reaches π, the downstream detection units C and D and the upstream detection unit C and D The phases of the output signals of the detectors A and B again coincide.
[0023]
When the pit depth of the ROM disk is not an integral multiple of ¼ wavelength in this way, the output signals of the detection units A and B on the upstream side of the detector 21 and the output signals of the detection units C and D on the downstream side A phase difference depending on the depth of the pits formed on the ROM disk occurs between the two, and this phase difference is included in the tracking error signal as an offset voltage, so that stable tracking control can be performed. There was a problem of disappearing.
[0024]
Therefore, in order to solve such a problem, the output signals of the detection units A and B on the upstream side of the detector 21 are delayed when the disk is formed with a pit depth shallower than a quarter wavelength. For example, a tracking control method in which a phase difference generated between the detection units A and B on the upstream side of the detector 21 and the detection units C and D on the downstream side of the detector 21 is removed depending on the depth of the pit is, for example, Japanese Patent Publication No. 6-3648. It is disclosed in the gazette.
[0025]
[Problems to be solved by the invention]
By the way, in recent years, due to the development of multimedia, a disk drive device corresponding to different types of disks such as CD and DVD and disks having different data area forms such as DVD-ROM and DVD-RAM has been demanded.
However, in the disk drive apparatus adopting the tracking control method as described above, for example, the upstream side of the detector 21 is adapted to correspond to a disk (for example, CD) whose pit depth is shallower than a quarter wavelength (2 / π). When the output signals of the detectors A and B are delayed, stable tracking control can be performed for the CD, but stable tracking is possible for, for example, a DVD-ROM where the CD and pit depths are different. Control cannot be performed. In other words, the disk drive device adopting the tracking control method as described above has a drawback that stable tracking servo control cannot be performed for a plurality of disks having different pit depths.
[0026]
In addition, the phase of crystal / amorphous can be changed by the method of heat reflection by a laser such as a DVD-R, DVD-RAM, etc., for example, a phase change medium, and information can be obtained by the difference in reflectance, the phase difference, or both. In a disc that can perform recording and reproduction of the above, for example, tracking control is performed by data recorded in the groove area as track guide information. In such a disc, the detector 21 depends on the depth of the groove. The phase difference generated between the output signals of the upstream detection units A and B and the output signals of the downstream detection units C and D is opposite to that of the pit.
[0027]
That is, as shown in FIG. 15B, when the groove depth is an integral multiple of a quarter wavelength (π / 2), the output signals of the detection units A and B on the upstream side of the detector 21 and the downstream side The phases of the output signals of the detectors C and D are the same as in the case of the pits, but when the groove depth is shallower than π / 2, the phases of the output signals of the upstream detectors A and B are on the downstream side. The phase lag of the output signals of the detection units C and D is delayed, and the phase lag of the output signals of the detection units A and B increases as the groove depth becomes shallower. When the groove depth reaches π / 4, the phase delay of the output signals of the detection units A and B becomes the maximum. Thereafter, as the groove depth becomes shallower, the phase lag of the output signals of the detectors A and B decreases, and when the pit depth becomes zero, the output signals of the detectors A and B and the detectors C and D The phases match again.
[0028]
On the other hand, when the depth of the groove becomes deeper than π / 2, the phase of the output signal of the upstream detection units A and B advances with respect to the phase of the output signal of the downstream detection units C and D, and the groove becomes deep. Therefore, the phase advance becomes large. When the groove depth reaches 3π / 4, the phase advance of the output signals of the upstream detection units A and B becomes maximum. Thereafter, as the groove depth increases, the phase advance of the output signals of the detectors A and B decreases, and when the groove depth reaches π, the phase of the output signals of the detectors A and B and the detectors C, The phase of the output signal of D again matches.
[0029]
Thus, when the depth of the groove is not an integral multiple of the quarter wavelength, it occurs between the output signals of the detection units A and B on the upstream side of the detector 21 and the output signals of the detection units C and D on the downstream side. The phase difference is opposite to that in the case of pits. In a disk drive device employing the tracking control method as described above, the track guide information is formed by the pits and the track guide information is stored in grooves or lands. There is a drawback that stable tracking servo control cannot be performed on the disk (area) to be formed.
[0030]
The present invention has been made to solve such problems, and an object of the present invention is to provide a disk drive apparatus capable of performing stable tracking control for a plurality of types of disk areas.
[0031]
[Means for Solving the Problems]
In order to achieve the above object, the disk drive apparatus of the present invention has first to fourth light receiving areas, and the first and second light receiving areas and the third and fourth light receiving areas are disk-shaped recording media. The first and fourth light receiving areas and the second and third light receiving areas are divided by a dividing line corresponding to a direction orthogonal to the tangential direction of the track. Said Photodetection means divided by a dividing line corresponding to the tangential direction of the track of the disk-shaped recording medium, and first to fourth delaying means for delaying signals obtained from the first to fourth light receiving areas, respectively. When, A discriminating means for discriminating the type of the disc-shaped recording medium, and corresponding to the depth of the guide groove formed in the disc-shaped recording medium detected by the discrimination result of the discriminating means, Output signals output from the first and second light receiving areas located upstream with respect to the rotation direction of the disk-shaped recording medium are delayed by the first and second delay means, or the disk-shaped recording is performed. Selectively controlling whether the output signals output from the third and fourth light receiving regions located downstream of the rotation direction of the medium are delayed by the third and fourth delay means; And a tracking control signal generating means for generating a tracking control signal from the output signals output from the first to fourth delay means.
[0032]
The tracking control signal generating means adds the sum of the output signal of the first delay means and the output signal of the third delay means, and adds the output signal of the second delay means and the output signal of the fourth delay means. The track control signal is generated by comparing the phase with the value.
[0033]
The tracking control signal generating means includes a phase comparison result between the output signal of the first delay means and the output signal of the fourth delay means, the output signal of the second delay means, and the output signal of the third delay means. The phase comparison results are added to generate a tracking control signal.
[0041]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the disk drive apparatus according to the embodiment of the present invention will be described as an example and described in the following order.
<1. First Embodiment>
1-1. Configuration of the main part of the playback system of a disk drive device
1-2. Configuration of tracking control block
1-3. When a ROM type disk is loaded in the disk drive
1-4. When a RAM type disk is loaded in the disk drive
1-5. Other configurations of tracking control block
<2. Second Embodiment>
2-1. Configuration of tracking control block
2-2. Other configurations of tracking control block
[0042]
<1. First Embodiment>
1-1. Configuration of the main part of the playback system of a disk drive device
FIG. 1 is a block diagram showing the configuration of the main part of the reproduction system of the disk drive apparatus of this example.
The disk D indicates a pit disk (for example, CD, CD-ROM), a groove disk (for example, magneto-optical disk (MO disk), DVD-R, DVD-RAM), and the disk D is a turntable. 7 and is driven to rotate at a constant linear velocity (CLV) or a constant angular velocity (CAV) by the spindle motor 1 during the reproduction operation.
Then, the data (main data) recorded in the pit form on the disk D is read by the pickup 1.
[0043]
The pickup 1 is provided with an optical system (in some cases, a plurality of optical systems) compatible with, for example, DVD-ROM, DVD-RAM, CD, and MO. For example, as an optimum optical system for a DVD-ROM, the laser diode 4 serving as a laser light source has an output laser center wavelength of 650 nm or 635 nm, and the objective lens 2 has NA = 0.6.
The objective lens 2 is held by a biaxial mechanism 3 so as to be movable in the tracking direction and the focus direction.
[0044]
The data reading operation is performed using the pickup 1 with respect to the disk D. In the pickup 1, the reflected light information from the disk D is detected by the detector 5 and converted into an electrical signal corresponding to the amount of received light. It is supplied to the RF amplifier 9.
The RF amplifier 9 includes a current-voltage conversion circuit, an amplifier circuit, a matrix operation 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.
The configuration of the tracking control block that generates the tracking error signal TE provided in the RF amplifier 9 will be described later.
[0045]
The detector 5 includes a dividing line parallel to the tangential direction of the track of the disk as shown in FIG. 2 and a detector 21 divided into four by a dividing line perpendicular to the dividing line, and is upstream of the rotation direction of the disk. Are provided with detectors A and B, and detectors C and D, respectively, on the downstream side. In this case, the focus error signal FE is generated by calculating (A + C)-(B + D) for the outputs of the detection units A, B, C, and D. The pull-in signal PI = (A + B + C + D).
[0046]
Various signals generated by the RF amplifier 9 are supplied to the binarization circuit 11 and the servo processor 14. That is, the reproduction RF signal from the RF amplifier 9 is supplied to the binarization circuit 11, and the focus error signal FE, tracking error signal TE, and pull-in signal PI are supplied to the servo processor 14.
[0047]
The reproduction RF signal obtained by the RF amplifier 9 is binarized by the binarization circuit 11 so as to be a so-called EFM + signal (8-16 modulation signal) in the case of DVD, for example, and supplied to the decoder 12. The decoder 12 performs EFM + demodulation, CIRC decoding, etc., and performs CD-ROM decoding, MPEG decoding, etc. as necessary to reproduce information read from the disk D.
The decoded data is supplied to an external connection device such as a host computer via the interface unit 13.
[0048]
The servo processor 14 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 9 and the spindle error signal SPE from the decoder 12 or the system controller 10. Execute servo operation.
[0049]
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 16. The biaxial driver 16 applies current based on the focus drive signal and tracking drive signal to the focus coil and tracking coil of the biaxial mechanism 3 in the pickup 1 to drive the biaxial mechanism 3. As a result, a tracking servo loop and a focus servo loop are formed by the pickup 1, the RF amplifier 9, the servo processor 14, and the biaxial driver 16.
[0050]
The servo processor 14 supplies the spindle motor driver 17 with a spindle drive signal generated according to the spindle error signal SPE. The spindle motor driver 17 applies, for example, a three-phase drive signal to the spindle motor 6 according to the spindle drive signal, and causes the spindle motor 6 to perform CLV rotation. Further, the servo processor 14 generates a spindle drive signal in response to a spindle kick (acceleration) / brake (deceleration) control signal from the system controller 11 and causes the spindle motor driver 17 to start or stop the spindle motor 6. .
[0051]
The servo processor 14 generates a thread drive signal based on, for example, a thread error signal obtained from a low frequency component of the tracking error signal TE, access execution control from the system controller 10, 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 sled mechanism 8 is a mechanism that moves the entire pickup 1 in the radial direction of the disk. The sled driver 17 drives the sled motor 8 in accordance with a sled drive signal, so that the proper slide movement of the pickup 1 is performed.
[0052]
The laser diode 4 in the pickup 1 is driven to emit laser light by a laser driver 18.
The servo processor 14 generates a laser drive signal for executing laser emission of the pickup 1 during reproduction based on an instruction from the system controller 10 and supplies the laser drive signal to the laser driver 18. In response to this, the laser driver 18 drives the laser diode 4 to emit light.
[0053]
Various operations such as servo and decoding as described above are controlled by a system controller 10 formed by a microcomputer.
For example, operations such as playback start, end, track access, fast forward playback, and fast reverse playback are realized by the system controller 10 controlling the operations of the servo processor 14 and the pickup 1.
[0054]
1-2. Configuration of tracking control block
Next, FIG. 3 shows the configuration of the tracking control block provided in the RF amplifier 9 of the disk drive device as described above.
In this figure, a delay circuit 22 surrounded by a broken line is provided with delay circuits 22a, 22b, 22c and 22d for delaying the outputs of the detectors A, B, C and D of the quadrant detector 21, respectively.
[0055]
The adder 23a adds the output signal from the delay circuit 22a and the output signal from the delay circuit 22c, and outputs a sum signal. The adder 23b adds the output signal of the delay circuit 22b and the output signal of the delay circuit 22d and outputs a sum signal.
[0056]
The HPF / waveform shaping circuits 24a and 24b perform waveform shaping of signals output from the adders 23a and 23b, respectively, and remove low-frequency components by a high-pass filter (HPF).
For example, when the loaded disk is a disk having a groove, the output signal obtained from the detectors A to D of the detector 21 includes a modulation component due to a light intensity change that appears when the light spot crosses the groove. As shown in FIG. 10 (a), the envelope of the output waveform becomes an asymmetric waveform on the + side and the − side. When the output error signal S is binarized to generate a tracking error signal, the tracking error signal TE between tracks L deteriorates as shown in FIG.
[0057]
Therefore, the output signals S obtained from the detectors A to D of the detector 21 are sent to the HPF / waveform shaping circuits 24a and 24b. _A ~ S _D An HPF having a high cut-off frequency is provided so as to sufficiently attenuate the modulation component (low-frequency component) due to the groove included in the. As a result, the output signal S obtained from the detectors A to D of the detector 21 becomes a signal from which the modulation component due to the groove has been removed as shown in FIG. 11A, for example, and the groove as shown in FIG. Thus, a tracking error signal TE which is not deteriorated due to the influence of the modulation component due to is obtained.
[0058]
The phase comparator 25 compares the phase of the output signal of the HPF / waveform shaping circuit 24a with the output signal of the HPF / waveform shaping circuit 24b and outputs a comparison signal.
The LPF 26 is a low-pass filter, and smoothes the comparison signal output from the phase comparator 25 and outputs it as a tracking error signal TE.
[0059]
The disc discriminating circuit 27 is a discriminating circuit that discriminates the type of the loaded disc and the type of the reproduction area on the disc (that is, whether it is a pit area or a groove area). The type of the area is determined based on the management information recorded on the inner circumference side and the address read during reproduction.
[0060]
The disc discrimination circuit 27 discriminates the disc type using the reflected light information obtained when the laser beam is focused on the disc surface and the reflected light information obtained when the laser beam is focused on the signal surface of the disc. You may make it do. That is, for example, while the focal position of the laser beam is forcibly changed within a variable range at a predetermined speed, the timing at which the disc surface is focused from the light amount signal or the focus error signal and the timing at which the disc signal surface is focused. You may make it discriminate | determine whether it is CD or DVD based on the measured value by measuring a time difference.
[0061]
The delay control circuit 28 discriminates the type and area of the loaded disc based on the discrimination result discriminated by the disc discriminating circuit 27, and the delay of any one of the delay circuits 22a and 22b or the delay circuits 22c and 22d is delayed. Control the time.
That is, the delay control circuit 28 determines the output signals of the detection units A and B on the upstream side of the detector 21 and the downstream side depending on the depth of the pits or grooves in which the track guide information is formed based on the disc or area discrimination results. The delay times of the delay circuits 22a and 22b or the delay circuits 22c and 22d are controlled so as to eliminate the phase difference generated between the output signals of the detection units C and D.
[0062]
Hereinafter, an operation when a tracking error signal is generated by the tracking control block as described above will be described.
1-3. When a ROM type disk is loaded in the disk drive device First, a case where a ROM type disk is loaded on the turntable 7 of the disk drive device of this example shown in FIG. 1 will be described.
When a ROM type disk is loaded, the type of the loaded disk is first determined by the disk determination circuit 27 and the determination result is output to the delay control circuit 28. The delay control circuit 28 controls the delay time of either the delay circuit 22a or 22b or the delay circuit 22c or 22d based on the determination result of the disk determination circuit 27.
[0063]
In the state where the disc type is discriminated by the disc discriminating circuit 27 in this way, the data reading operation is performed by the pickup 1, and the reflected light information from the disc is detected by the detector 21 in the pickup 1.
[0064]
Here, the depth of the pit of the loaded disc (here, the pit depth is a depth obtained by subtracting an integral multiple of π from the actual physical pit depth as described above). In the case of (for example, CD), the output signal S output from the detectors A and B located on the upstream side of the detector 21. _A , S _B Is a waveform as shown in FIG. 4A, and the output signals S of the detection units C and D located on the downstream side. _C , S _D Has a waveform as shown in FIG.
[0065]
That is, S of the output signal of the detectors A and B on the upstream side of the detector 21 _A , S _B Is the output signal S of the downstream detection units C and D _C , S _D Compared to the output signal S, the waveform is advanced in phase by a predetermined time T. _A ~ S _D Are respectively supplied to the delay circuits 22a to 22d.
[0066]
At this time, the delay circuits 22a to 22d are connected to the output signals S of the detectors A and B on the upstream side of the detector 21 supplied to the delay circuits 22a and 22b by the delay control circuit 28. _A , S _B Is delayed by the time T, and the output signal S output from the delay circuits 22a to 22d. _A '~ S _D 'Of the output signals S of the delay circuits 22a and 22b. _A ', S _B 'Is the output signal S of the detectors A and B indicated by broken lines as shown in FIG. _A , S _B Is delayed by time T. That is, the output signal S of the delay circuits 22a and 22b. _A ', S _B 'And the output signal S of the delay circuits 22c and 22d _C ', S _D 'Will be in phase.
[0067]
As a result, the output signals S of the detectors A and B on the upstream side of the detector 21 depend on the pit depth. _A , S _B And the output signal S of the downstream detection units C and D _C , S _D The phase difference generated between the two is removed.
Therefore, the output signal S of the delay circuits 22a and 22c. _A ', S _C 'Is added by the adder 23a and the output signal S of the delay circuits 22b and 22d _B ', S _D 'Is added by the adder 23b, the respective sum signals are waveform-shaped by the HPF / waveform shaping circuits 24a and 24b, and then supplied to the phase comparator 25. Then, phase comparison is performed by the phase comparator 25, and the comparison signal is output as a tracking error signal via the LPF 26.
[0068]
On the other hand, when the pit depth of the loaded disc is greater than π / 2 and shallower than π, the output signal S output from the detectors A and B located upstream of the detector 21. _A , S _B Output signals S of the detection units C and D located downstream of _C , S _D In this case, since the disc type is discriminated by the disc discriminating circuit 27, the delay control circuit 28 outputs the output signals S of the detection units C and D on the downstream side of the detector 21. _C , S _D Can be controlled so as to be delayed by a predetermined time T. Therefore, the output signal S of the detectors A and B on the upstream side of the detector 21 _A , S _B And the output signal S of the downstream detection units C and D _C , S _D Can be eliminated.
[0069]
If the disc discriminating circuit 27 discriminates that the rotation direction of the disc loaded for some reason is rotating in the direction opposite to the direction indicated by the arrow in FIG. 3, the upstream side and the downstream side of the detector 21 are detected. Since the positions are reversed, in this case, for example, when the pit depth is shallower than π / 2, the delay control circuit 28 outputs the output signals S of the detection units C and D downstream of the detector 21. _C , S _D Is delayed by a predetermined time T, and when the pit depth is deeper than π / 2 and shallower than π, the output signals S of the detectors A and B on the upstream side of the detector 21 _A , S _B May be delayed by a predetermined time T.
[0070]
1-4. When a RAM type disk is loaded in the disk drive device Next, track guide information is recorded as a RAM disk (that is, a disk having a groove area) on the disk drive device of this example shown in FIG. A case where a magneto-optical disk is loaded will be described. Also in this case, first, the type of the disc loaded is discriminated by the disc discriminating circuit 27, and the discrimination result is output to the delay control circuit 28. The delay control circuit 28 controls the delay time of either the delay circuit 22a or 22b or the delay circuit 22c or 22d based on the determination result of the disk determination circuit 27.
[0071]
In this state where the disc type is discriminated by the disc discriminating circuit 27, the reflected light information from the groove is detected by the detector 21 by the pickup 1.
[0072]
Here, the groove depth of the loaded disk (the groove depth here is a depth obtained by subtracting an integer multiple of π from the actual physical groove depth as described above) is π / 2. If it is shallower, the output signal S output from the detectors A and B located upstream of the detector 21. _A , S _B Is a waveform as shown in FIG. 5A, and the output signals S of the detectors C and D located on the downstream side of the detector 21. _C , S _D Has a waveform as shown in FIG.
[0073]
That is, S of the output signal of the detectors A and B on the upstream side of the detector 21 _A , S _B Is the output signal S of the downstream detection units C and D _C , S _D Compared with the output signal S, the phase is delayed by the time T, and such an output signal S _A ~ S _D Are respectively supplied to the delay circuits 22a to 22d.
[0074]
At this time, the delay circuits 22a to 22d are supplied to the delay circuits 22c and 22d by the delay control circuit 28, and output signals S from the detectors C and D on the downstream side of the detector 21. _C , S _D Is delayed by the time T, and the output signal S output from the delay circuits 22a to 22d. _A '~ S _D Output signal S output from the delay circuits 22c and 22d. _C ', S _D 'Is the output signal S of the detection units C and D indicated by broken lines as shown in FIG. _C , S _D Is delayed by time T. That is, the output signal S of the delay circuits 22a and 22b. _A ', S _B 'And the output signal S of the delay circuits 22c and 22d _C ', S _D 'And the phase will match.
[0075]
As a result, the output signal S of the detectors A and B on the upstream side of the detector 21 depends on the depth of the groove. _A , S _B And the output signal S of the downstream detection units C and D _C , S _D The phase difference generated between the two is removed.
Therefore, the output signal S of the delay circuits 22a and 22c. _A ', S _C 'Is added by the adder 23a and the output signal S of the delay circuits 22b and 22d _B ', S _D 'Is added by the adder 23b, and each sum signal is filtered and waveform-shaped by the HPF / waveform shaping circuits 24a and 24b, and then supplied to the phase comparator 25. Then, phase comparison is performed by the phase comparator 25, and the comparison signal is output as a tracking error signal via the LPF 26.
[0076]
On the other hand, when the depth of the groove of the loaded disk is greater than π / 2 and shallower than π, the output signals S of the detection units C and D on the downstream side of the detector 21 are detected. _C , S _D Output signals S of the upstream detection units A and B _A , S _B In this case, since the disc type is discriminated by the disc discriminating circuit 27, the output signals S of the detection units A and B upstream of the detector 21 are discriminated by the delay control circuit 28. _A , S _B Can be controlled so as to be delayed by a predetermined time T.
Therefore, the output signal S of the detectors A and B on the upstream side of the detector 21 _A , S _B And the output signal S of the downstream detection units C and D _C , S _D Can be eliminated.
[0077]
If the disc discriminating circuit 27 determines that the rotation direction of the loaded disc is rotating in the direction opposite to the direction indicated by the arrow in FIG. 3 for some reason, the upstream side and the downstream side of the detector 21 are detected. Since the positions are reversed, the control of the delay circuits 22a and 22b and the delay circuits 22c and 22d by the delay control circuit 28 may be switched in this case as well.
[0078]
In the case of a groove disc, there are a groove recording method in which data is recorded in the groove and a land recording method in which data is recorded in the land. The above description is for the groove recording method, and in the case of the land recording method. Is the output signal S of the detectors A and B upstream of the detector 21. _A , S _B And the output signal S of the downstream detection units C and D _C , S _D The phase difference generated between and is opposite to that shown in FIG. Therefore, in this case, the control of the delay circuit 22 by the delay control circuit 28 may be switched.
[0079]
Thus, in the tracking control block of this example, the disc discriminating circuit 27 discriminates the type of disc, the disc area, and the rotation direction of the disc, and based on the discrimination result, the delay control circuit 28 sets the upstream side of the detector 21. Since the delay time of the detection units A and B located on the downstream side or the detection units C and D located on the downstream side can be controlled, the upstream detection unit A generated by the depth of pits and grooves formed on the disk. , B and the output signals of the downstream detection units C, D can be eliminated. Therefore, in the disk drive device having such a tracking control block, stable tracking servo control can be performed on a plurality of different types of disks and a plurality of different areas.
[0080]
1-5. Other configurations of tracking control block
Next, FIG. 6 shows another configuration example of the tracking control block.
Note that the same blocks as those in FIG.
The tracking control block shown in this figure has an output signal S from the delay circuit 22a. _A 'Is sent to the HPF / waveform shaping circuit 24c and the output signal S of the delay circuit 22b. _B 'Is sent to the HPF / waveform shaping circuit 24b and the output signal S of the delay circuit 22c. _C 'Is sent to the HPF / waveform shaping circuit 24a and the output signal S of the delay circuit 22d. _D 'Is supplied to the HPF / waveform shaping circuit 24d, and the output signal S supplied from each HPF / waveform shaping circuit 24a to 24d. _A '~ S _D The low-frequency component of 'is removed and waveform shaping is performed.
[0081]
The output signals of the HPF / waveform shaping circuit 24a and the HPF / waveform shaping circuit 24b are supplied to the phase comparison 25a, and the output signals of the HPF / waveform shaping circuit 24c and the HPF / waveform shaping circuit 24d are output to the phase comparison 25b. Phase comparison is performed in the units 25a and 25b.
Therefore, if the output signals of the phase comparator 25a and the phase comparator 25b are added by the adder 23 and the sum signal is output via the LPF 26, the tracking error signal TE can be generated.
[0082]
Also, for example, the disk loaded in the disk drive device is a RAM type disk and the groove depth (here, the groove depth is the actual physical groove depth as described above minus an integer multiple of π). The output signal S of the detectors C and D downstream of the detector 21 is always limited to a disk whose depth is less than π / 2. _C , S _D Therefore, the tracking control block may be configured as shown in FIG.
In other words, in this case, the output signal S of the detectors C and D downstream of the detector 21 is used as the delay circuit 22. _C , S _D It is sufficient to provide only delay circuits 22c and 22d for delaying. Other configurations are the same as those of the tracking control block shown in FIG.
[0083]
Thus, when the disk loaded in the disk drive device is a RAM type disk and the groove depth is limited to a disk shallower than π / 2, the delay circuit 22 can be simplified.
[0084]
By the way, in the tracking control block of the disk drive device according to the first embodiment of the present invention as described above, the disk discrimination circuit 27 discriminates the type of disk, the area of the disk, and the rotation direction of the disk. Based on the determination result, the delay control circuit 28 controls the delay times of the detectors A and B located on the upstream side of the detector 21 or the detectors C and D located on the downstream side. For this reason, for example, when applied to a disk drive apparatus corresponding to a large number of disks having different pit or groove depths formed on the disk, the delay time switching control in the control delay control circuit 28 becomes complicated. Conceivable.
[0085]
In addition, when applied to a disk drive device that rotates and reproduces a disk by the CAV (constant angular velocity) method, each time the linear velocity of the disk D changes, the detectors A and B positioned on the upstream side of the detector 21 or It is necessary to control the delay time of the detection units C and D located on the downstream side. For this reason, when applied to a disk drive device that is rotationally driven by the CAV method, it is expected that it becomes difficult to control the switching of the delay time in the delay control circuit 28.
[0086]
Therefore, it is not necessary to perform delay time switching control in the delay control circuit 28 even when the types and areas of the disks are different, and the configuration of the tracking control block suitable for the CAV type disk drive device is the second embodiment. explain.
[0087]
<2. Second Embodiment>
2-1. Configuration of tracking control block
FIG. 8 shows a configuration example of the tracking control block of the disk drive device according to the second embodiment of the present invention. Note that the same blocks as those in FIG.
The tracking control block shown in FIG. 8 includes an output signal S from the detection unit A among the output signals of the detection units A, B, C, and D of the quadrant detector 21. _A Output signal S from the detector B to the HPF / waveform shaping circuit 24a. _B Output signal S from the detection unit C to the HPF / waveform shaping circuit 24b. _C Output signal S from the detection unit D to the HPF / waveform shaping circuit 24c. _D Are supplied to the HPF / waveform shaping circuit 24d. In the HPF / waveform shaping circuits 24a to 24d, the supplied output signal S _A ~ S _D The low-frequency component contained in the signal is removed and the waveform is shaped and output.
[0088]
The output signals of the HPF / waveform shaping circuit 24a and HPF / waveform shaping circuit 24b are output to the phase comparator 25a, and the output signals of the HPF / waveform shaping circuit 24c and HPF / waveform shaping circuit 24d are output to the phase comparator 25b. Phase comparison. The comparison signals output from the phase comparators 25a and 25b are added by the adder 23, and the sum signal is output as a tracking error signal TE through the LPF 26.
[0089]
In the tracking control block configured as described above, output signals S from the detectors A to D of the detector 21 are output. _A ~ S _D After the waveform is shaped by the HPF / waveform shaping circuit 24, the output signals S from the detectors A and B on the upstream side of the detector 21 by the phase comparators 25a and 25b. _A , S _B And the output signal S from the downstream detection units C and D _C , S _D Each phase comparison is performed. That is, in the phase comparators 25a and 25b, the output signals S from the detectors A and B on the upstream side of the detector 21 are output. _A , S _B And an output signal S from the detection units C and D on the downstream side _C , S _D The phase comparison is performed.
[0090]
In this case, there is no phase difference caused by the type and area of the disk between the comparison signals output from the phase comparators 25a and 25b, so these comparison signals are added by the adder 23 and passed through the LPF 26. This makes it possible to generate a stable tracking error signal TE without an offset voltage caused by the type and area of the disk.
[0091]
As described above, according to the tracking control block according to the second embodiment of the present invention, the output signal S from the detectors A and B on the upstream side of the detector 21 depends on the type and area of the disk. _A , S _B Alternatively, the output signal S from the downstream detection units C and D _C , S _D Need not be delayed in accordance with the phase difference. Therefore, the output signal S from the disc discrimination circuit 27 for discriminating the type of disc to be loaded, the detection units A and B on the upstream side of the detector 21 and the detection units C and D on the downstream side. _A ~ S _D Without delay circuits 24a-24d for delaying and delay control circuit 28 for controlling the delay circuits 24a-24d, and without performing delay time switching control in the delay control circuit 28, a plurality of types of disks and a plurality of discs A stable tracking error signal TE can be generated for the disk in the area.
[0092]
2-2. Other configurations of tracking control block
Next, FIG. 9 shows another example of the configuration of the tracking control block according to the second embodiment of the present invention. Note that the same blocks as those in FIG.
As another configuration example of the tracking control block shown in FIG. 9, the output signal S from the detection unit A among the output signals of the detection units A, B, C, and D of the quadrant detector 21. _A Output signal S from the detector B to the HPF / waveform shaping circuit 24a. _B Are supplied to the HPF / waveform shaping circuit 24b. The HPF / waveform shaping circuits 24a and 24b supply the output signal S _A , S _B The low-frequency component contained in the signal is removed and the waveform is shaped and output.
[0093]
The output signals of the HPF / waveform shaping circuit 24 a and the HPF / waveform shaping circuit 24 b are output to the phase comparator 25 for phase comparison, and the phase comparison signal output from the phase comparator 25 is tracked via the LPF 26. An error signal TE is output.
[0094]
In the tracking control block having such a configuration, the output signal S from the detectors A and B of the detector 21 is detected. _A , S _B After the waveform is shaped by the HPF / waveform shaping circuit 24, the phase comparison is performed by the phase comparator 25.
In this case, the output signal S to be phase-compared by the phase comparator 25. _A , S _B Since there is no phase difference even when the type and area of the disc are different, the comparison signal output from the phase comparator 25 does not have a phase difference caused by the type and area of the disc. This makes it possible to generate a stable tracking error signal TE without an offset voltage caused by the type and area of the disk.
[0095]
The tracking control block configured as described above has an output signal S output from the detection units A and B on the upstream side of the detector 21. _A , S _B Since the HPF / waveform shaping circuits 24a and 24b for performing the low-frequency removal and the waveform shaping are provided, and the adder 25 for adding the output signals of the HPF / waveform shaping circuits 24a and 24b can be provided. Compared with the tracking control block shown in FIG. 8, the configuration can be further simplified. In the present embodiment, the output signal S of the detectors A and B on the upstream side of the detector 21. _A , S _B The tracking error signal is generated based on the output signal S output from the detection units C and D on the downstream side of the detector 21. _C , S _D , A tracking error signal may be generated.
[0096]
Incidentally, in the HPF / waveform shaping circuits 24 a to 24 d shown in FIGS. 8 and 9, the output signals S output from the detectors A to D of the detector 21, respectively. _A ~ S _D Waveform shaping, and a low-pass component is removed by a high-pass filter (HPF). For example, when the disk loaded in the same manner as described above is a disk having a groove, the output signal obtained from the detectors A to D of the detector 21 includes a modulation component due to a light intensity change that appears when the light spot crosses the groove. For example, as shown in FIG. 10A, the envelope of the output waveform becomes an asymmetric waveform on the + side and the − side. When the output error signal S is binarized to generate a tracking error signal, the tracking error signal TE between tracks L deteriorates as shown in FIG.
[0097]
Therefore, the output signals S obtained from the detectors A to D of the detector 21 are sent to the HPF / waveform shaping circuits 24a to 24d. _A ~ S _D An HPF having a high cut-off frequency is provided so as to sufficiently attenuate the modulation component (low-frequency component) due to the groove included in the. As a result, the output signal S obtained from the detectors A to D of the detector 21 becomes a signal from which the modulation component due to the groove has been removed as shown in FIG. 11A, for example, and the groove as shown in FIG. Thus, a tracking error signal TE which is not deteriorated due to the influence of the modulation component due to is obtained.
[0098]
In the tracking control block of this example, the case where the phase difference method for generating the tracking error signal by comparing the phase differences of the output signals of the detectors A to D of the detector 21 has been described. Of course, it is also possible to construct the block by the heterodyne method.
[0099]
【The invention's effect】
As explained above Book According to the invention, the discriminating means discriminates the type of the disc-shaped recording medium and the type of the drive execution area, and based on the discrimination result, the first and second light receiving areas or the third and fourth of the light detecting means. Since the output signal of the light receiving area is delayed by the first, second delay means, or the third, fourth delay means, it can be used for a plurality of types of disc-shaped recording media or a plurality of disc-shaped recording media. On the other hand, stable tracking control can be performed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a main part of a reproduction system of a disk drive apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of a detector.
FIG. 3 is a diagram showing a configuration of a tracking control block according to the first embodiment.
FIG. 4 is a diagram showing a waveform of an output signal obtained from a detector detection unit when a ROM type disk is loaded.
FIG. 5 is a diagram showing a waveform of an output signal obtained from a detector detection unit when a RAM type is loaded.
FIG. 6 is a diagram showing another configuration of the tracking control block according to the first embodiment.
FIG. 7 is a diagram showing a configuration of a tracking control block in a case where the RAM type disk according to the first embodiment is limited to a disk whose groove depth is shallower than π / 2.
FIG. 8 is a diagram showing a configuration of a tracking control block according to a second embodiment.
FIG. 9 is a diagram showing another configuration of the tracking control block according to the second embodiment.
FIG. 10 is a diagram showing a waveform of a detection signal obtained by a detector of a detector when a RAM disk is reproduced and a waveform of a tracking error signal at that time.
FIG. 11 is a diagram showing a waveform of a detection signal obtained by a detector of the detector when a RAM disk is reproduced and a waveform of a tracking error signal at that time.
FIG. 12 is a diagram illustrating the pit depth of a disc.
FIG. 13 is a diagram illustrating the groove depth of a disc.
FIG. 14 is a diagram for explaining the pit depth of a bonded disc.
FIG. 15 is a diagram showing the relationship between the depth of pits and grooves formed on a disc and the phase difference between a detection unit located on the upstream side and a detection unit located on the downstream side of the detector.
[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 RF amplifier, 10 system controller, 11 binarization circuit, 12 decoder, 13 interface , 14 Servo processor, 15 Thread driver, 16 Two-axis driver, 17 Spindle driver, 18 Laser driver, 21 Detector, 22 22a-22d Delay circuit, 23 Adder, 2424a-24d HPF / waveform shaping circuit, 25 25a 25b Phase comparison , 26 LPF, 27 disk discrimination circuit, 28 delay control circuit

Claims (3)

It has first to fourth light receiving areas, and the first and second light receiving areas and the third and fourth light receiving areas are dividing lines corresponding to a direction orthogonal to the track tangential direction of the disk-shaped recording medium. is divided, and the first and fourth light receiving region and the second, third photodetection means to the light receiving region is divided by a dividing line corresponding to a tangential direction of the track of the disc-shaped recording medium, said first First to fourth delay means for delaying signals obtained from the respective fourth light receiving areas, discrimination means for discriminating the type of the disc-shaped recording medium, and the detection result of the discrimination means Output signals output from the first and second light receiving regions located upstream of the rotational direction of the disc-shaped recording medium corresponding to the depth of the guide groove formed on the disc-shaped recording medium. By the first and second delay means; Whether the output signals output from the third and fourth light receiving areas located downstream with respect to the rotation direction of the disc-shaped recording medium are delayed by the third and fourth delay means. Delay control means capable of selectively controlling the tracking control signal, and tracking control signal generation means for generating a tracking control signal from the output signals output from the first to fourth delay means. Disk drive device. The tracking control signal generating means includes an added value of the output signal of the first delay means and the output signal of the third delay means, the output signal of the second delay means, and the output of the fourth delay means. disk drive according to claim 1, characterized in that as by comparing the phases of the sum value of the signal to generate a Tracking in g control signal.   The tracking control signal generating means includes a phase comparison result between the output signal of the first delay means and the output signal of the fourth delay means, the output signal of the second delay means, and the third delay means. 2. The disk drive device according to claim 1, wherein the tracking control signal is generated by adding the phase comparison results of the output signals.

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