JP2004335104A - Optical storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize the eccentricity correction when a medium is loaded by measuring the eccentricity information necessary for an eccentricity correction efficiently and precisely. <P>SOLUTION: The device is provided with an eccentricity measuring part which measures the eccentricity amplitude amp and an eccentricity phase Tϕ to a rotational reference position as the eccentricity information based on the detection of the zero crossing of a tracking error signal under the condition that the drive of a carriage and lens by a positioner is stopped; an eccentricity memory which stores a sine value for one rotation in accordance with the rotational position of the medium; and an eccentricity correcting part which finds the medium eccentricity quantity from the sine value read from the eccentricity memory and eccentricity measurement information by the measuring part and controls the positioner so that the eccentricity quantity may be countervailed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an optical storage device using a rewritable medium such as a CD or MO cartridge, and more particularly to an optical storage device that further improves access performance to a high-density recording medium.

  An optical disk has been attracting attention as a core storage medium of rapidly developing multimedia in recent years. For example, in the case of a 3.5-inch MO cartridge, in addition to the conventional 128 MB and 230 MB, in recent years, 540 MB and High-density recording media such as 640 MB are also being provided. For this reason, it is desired that all media such as 180 MB, 230 MB, 540 MB and 640 MB that can be currently used can be used as an optical disk drive.

  In recent years, a personal computer which has been rapidly spread has a function of reproducing a compact disk (CD) known only for reproduction, and is a rewritable optical disk device in addition to a CD optical disk drive. Mounting the optical disk drive of the MO cartridge is difficult in terms of space and cost.

  Therefore, in recent years, an optical disk drive that can use both an MO cartridge and a CD has been developed. This CD / MO shared type optical disk drive uses the optical system, the mechanical structure, and the controller circuit as much as possible for the CD and the MO cartridge.

  By the way, in an optical disk drive capable of using a high-density recording medium such as 540 MB or 640 MB, the track pitch of the medium becomes narrower as the recording density increases, and the beam of the optical head is moved to a target track. It is necessary to improve seek accuracy for positioning. In order to improve the seek accuracy, it is possible to stably pull in the target track by suppressing the seek speed.

  Normally, seek control to a target track is performed by a lens actuator mounted on a carriage driven by a VCM, for example, for a short seek within 50 tracks, and a carriage control by a VCM for a long seek exceeding 50 tracks. The seek control is performed by both the driving and the carriage driving by the lens actuator.

  In such seek control, first, speed control is performed using a target speed generated according to the number of remaining tracks to the target track. Immediately before the number of remaining tracks to the target track becomes one or two tracks by the speed control, a predetermined deceleration current is passed to perform deceleration control, and at the end of deceleration, switching to the position servo control is performed to pull into the on-track state.

For such seek control, in order to enhance the seek performance in a high-density recording medium of 540 MB or 640 MB, the moving speed of the beam is reduced to near zero speed with a predetermined deceleration current immediately before the target track, and the on-track state is set. It is necessary to control the pull-in stably.
JP-A-03-058358

  However, in such a conventional seek control of an optical disk drive, if the target speed of the speed control is set to be high in order to shorten the seek time, the latter half of the speed control by the speed control is rapidly performed. The pull-in speed just before the target track may vary greatly. Therefore, in the deceleration control using the fixed deceleration current, there is a problem that the target track is over due to insufficient deceleration, or the beam is returned due to excessive deceleration, and it takes time to settle on the target track. Was.

  Of course, if the target speed of the speed control is suppressed, the pull-in speed immediately before the target track can be stabilized, but since the target speed is low, the speed control takes time, and even if the settling time can be shortened, the overall seek time is reduced. It will be long.

  This problem also applies to one-track seek control in which a beam is moved using an adjacent track as a target track. In the conventional one-track seek control, one-track seek period is equally divided into three, for example, an acceleration period, a zero current period, and a deceleration period, and a fixed acceleration current and a deceleration current are sequentially determined. Feed-forward control for flowing to the lens actuator is performed.

  However, the acceleration characteristics and deceleration characteristics of the beam by the lens actuator vary for each optical disk drive. For this reason, if the acceleration current or the deceleration current is insufficient, the seek time is prolonged. On the other hand, if the acceleration current or the deceleration current is too large, the settling time is prolonged, so that there is a problem that sufficient one-track seek performance cannot be expected.

  Accordingly, an object of the present invention is to provide an optical storage device that improves seek performance by achieving both high-speed seek and shortening of settling time for each of normal seek control and one-track seek control.

  In addition, the present invention provides a control for moving a light beam to a target track mainly by a lens actuator, that is, a so-called track jump control. It is an object of the present invention to provide an optical storage device capable of being pulled into a track state.

  Further, in an optical disk drive using a replaceable medium such as a magneto-optical disk or a CD, the track eccentricity of the loaded medium is different for each medium, and the amount of eccentricity of the medium at the stage of initialization processing after loading is different. The eccentricity is measured, and an eccentric offset current is supplied to the VCM in synchronization with the rotation of the medium so as to cancel the measured eccentricity.

  When the track is regarded as a straight line, the medium eccentricity draws a sin curve. Therefore, a so-called eccentricity memory such as a RAM in which a sine value having a rotation angle of a predetermined resolution as an address is stored in advance is prepared, and the eccentricity information is used as the eccentricity information. From the measured amplitude and the phase with respect to the rotation reference position, the corresponding cosine value is read from the eccentric memory in synchronization with the actual medium rotation position to determine the amount of eccentricity, and an offset current is supplied so as to cancel the eccentricity.

  The measurement of the amount of eccentricity performed in the initialization processing after the conventional medium loading is obtained by one rotation of the medium in an on-track control state using a lens actuator, for example, using a lens position sensor that detects the position of an objective lens mounted on a carriage. The eccentric amplitude and phase are measured from the lens position signal.

  However, since the lens position sensor is originally used for the position servo of the lens lock for keeping the objective lens mounted on the carriage at the zero position (neutral position), the linearity and resolution of the detection signal with respect to the position are not so high. Since the signal is not high and the signal is an analog signal, an error occurs when AD conversion is performed, and there is a problem that highly reliable measurement of eccentricity information cannot be sufficiently performed.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an optical storage device that optimizes eccentricity correction by efficiently and accurately measuring eccentricity information required for eccentricity correction when loading a medium.

  In a conventional optical disk drive, return light from a medium is detected by a two-segment detector, and a tracking error signal is obtained from a difference between two light receiving signals. In this case, the ID portion of the medium records a zone number, a track number, and the like by embossing called a pit, the return light is attenuated by the pit of the ID portion, a noise-like drop variation appears in the tracking error signal, and the amplitude is reduced. In the low part, the zero crossing is erroneously made, and the counting of the number of tracks is erroneously performed.

  Therefore, in order to suppress the fluctuation due to the return light of the ID section, envelope detection is performed to smooth the profile of the tracking error signal.

  However, although there is no problem with a 540 MB or 640 MB MO cartridge medium for high-density recording, in the case of a conventionally used 128 MB MO cartridge medium, a mirror surface structure is provided between the ID part of the medium surface and the MO recording part. And in the case of a 230 MB MO cartridge medium, the mirror portion is similarly left in an area other than the user area.

  Therefore, when an MO cartridge from 128 MB to 640 MB can be used in one optical disk drive, when the 128 MB or 230 MB MO cartridge is loaded and the envelope detection is performed when the tracking error signal is generated, the same level is used. By taking the difference between the light receiving signals of the mirror sections having the above, the tracking error signal is lost in the mirror section. Further, signal loss corresponding to the discharge time constant due to the envelope detection is caused, and the tracking error signal is greatly distorted, so that the track count due to zero crossing is always erroneous.

  Further, regardless of the medium, if the envelope detection is performed, the peak level above and below the tracking error signal itself is detected by the envelope detection during high-speed seek in which the zero-crossing time interval of the tracking error signal is short. Also, there is a problem that the tracking error signal is lost.

  Accordingly, it is an object of the present invention to provide an optical storage device capable of appropriately generating a tracking error signal even with respect to the presence / absence of a mirror portion and high-speed seek due to a difference in medium.

  Further, the conventional optical disk drive is provided with a focus servo for performing focus control on the medium surface of the objective lens mounted on the carriage. The focus servo generates a focus error signal based on the light receiving output of the medium return light.

  However, since the ID portion on the track of the MO cartridge medium is a physical pit, the in-focus position of the objective lens differs with respect to the recording surfaces of the MO portions on both sides. The focus error signal changes in a stepwise manner at the boundary portion of, and unnecessary focus control is performed.

  For example, in the case of a 540 MB MO cartridge medium, the outer track has 84 sectors and the inner track has 54 sectors, and the ID portions corresponding to the number of sectors are provided. There is a problem that current consumption increases.

  Of course, it is sufficient to turn off the focus servo for the ID section. However, turning on and off the focus servo at high speed in conjunction with the ID section results in a large disturbance to the servo system, which impairs the autofocus function. Would.

Accordingly, an object of the present invention is to provide an optical storage device that eliminates useless movement of the focus servo by the ID unit without impairing the function of the focus servo.

  FIG. 1 is a diagram illustrating the principle of the present invention. First, an optical storage device (hereinafter, referred to as an “optical disk drive”) of the present invention enables a carriage 76 to be movable in a direction crossing a track of a medium by a VCM 64 as a carriage actuator, and an optical unit is mounted on the carriage 76 and an objective lens 80 is mounted on the carriage 76. It comprises a movable optical system provided and a fixed optical system 78 fixedly arranged on the housing side, and records / reproduces information on / from a track of a medium using a light beam.

  The objective lens 80 of the moving optical system mounted on the carriage 76 moves the light beam from the fixed optical system 78 in a direction crossing the track of the medium by driving the lens actuator 60. The tracking error signal creation circuit 50 creates a tracking error signal E2 corresponding to the position of the light beam in the direction crossing the track, based on the light receiving output of the medium return light obtained by the optical unit. When an access to the target track is instructed by the host device, the access control unit 15 such as a DSP moves the light beam to the target track and controls the light beam to be on-track by controlling both the VCM 64 and the lens actuator 56.

  According to the present invention, there is provided an optical storage device that optimizes eccentricity correction by efficiently and accurately measuring eccentricity information required for eccentricity correction during medium loading.

  For this reason, the present invention provides an eccentricity measuring unit that measures the eccentricity phase Tφ with respect to the eccentricity amplitude amp rotation reference position as eccentricity information based on the detection of the zero crossing of the tracking error signal in a state in which the carriage and the lens are not driven by the positioner, The eccentricity memory which stores the sine value for one rotation corresponding to the rotation position of the medium, and the eccentricity amount read from the eccentricity memory and the eccentricity measurement information by the measurement unit determine the medium eccentricity amount so as to cancel the eccentricity amount. An eccentricity correction unit for controlling the positioner is provided.

  The eccentricity correction unit obtains an eccentricity amplitude Eamp by multiplying a half of the number of zero crosses of a tracking error signal of one rotation of the medium obtained in synchronization with a medium detection signal indicating one rotation of the medium by a track pitch TP. Further, the time from the start position of one rotation of the rotation detection signal to the middle point of the maximum zero-cross interval time of the tracking error signal is obtained as the eccentric phase Tφ.

  When the difference (tx−Tφ) between the elapsed time tx of the current rotation position with respect to the rotation reference position and the eccentric phase Tφ is negative, the eccentricity measurement unit obtains the difference by adding one rotation time Trot to the difference (tx−Tφ + Trot). The sine value sin2πf (tx−Tφ + Trot) is read from the eccentric memory and corrected. Here, f is an eccentric period determined by the number of rotations of the medium. When the difference (tx−Tφ) is zero or positive, the sine value sin2πf (tx−Tφ) obtained from the difference is read from the eccentric memory and corrected.

  The eccentricity measurement unit measures the number of zero crossings in one rotation in an eccentricity correction state based on the measured eccentricity information, and performs a measurement process if the number of zero crossings due to the eccentricity correction exceeds the number of zero crossings at the time of measurement. Is characterized in that the eccentric phase Tφ obtained in step (1) is corrected to the opposite phase. The correction in the case of the opposite phase may be made to be the eccentric opposite phase (Tφ + Trot / 2) obtained by adding a half of one rotation time Trot to the measurement phase Tφ.

  That is, in one measurement process, it cannot be determined whether the eccentric phase with respect to the start position of one rotation is correct or the opposite phase shifted by 180 degrees. Then, eccentricity correction based on the measured eccentricity information is performed, and if the number of zero crossings in one rotation is reduced by the correction, it is understood that the phase is correct. If the number of zero crosses increases, the phase is reversed, so this is corrected. Therefore, a correct eccentric phase can always be set as a measurement result.

  The eccentricity measurement unit performs measurement of the eccentricity information and eccentricity correction after the measurement twice, and compares the number of zero crossings in one rotation after each eccentricity correction. If the difference exceeds a predetermined threshold, the eccentricity measurement unit is equal to or less than the threshold. The measurement and correction of the eccentricity are repeated until. As a result, even if an erroneous eccentricity measurement is performed due to vibration or the like during the eccentricity measurement, a correct measurement result of the eccentricity information is always obtained without being affected by the eccentricity measurement.

  The eccentric memory stores a constant read cycle set by the number of samples of the DSP and a sine value for one rotation of a number determined by the medium rotation speed. Update the sine value for one rotation of the number determined by the medium rotation speed. For example, if the MO medium has 36 data at 3600 rpm (sine value every 10 degrees of rotation), the CD medium has 2400 rpm and 54 data (sine value every about 6.7 degrees of rotation).

  However, in such a conventional seek control of an optical disk drive, if the target speed of the speed control is set to be high in order to shorten the seek time, the latter half of the speed control by the speed control is rapidly performed. The pull-in speed just before the target track may vary greatly. Therefore, in the deceleration control using the fixed deceleration current, there is a problem that the target track is over due to insufficient deceleration, or the beam is returned due to excessive deceleration, and it takes time to settle on the target track. Was.

  Of course, if the target speed of the speed control is suppressed, the pull-in speed immediately before the target track can be stabilized, but since the target speed is low, the speed control takes time, and even if the settling time can be shortened, the overall seek time is reduced. It will be long.

  This problem also applies to one-track seek control in which a beam is moved using an adjacent track as a target track. In the conventional one-track seek control, one-track seek period is equally divided into three, for example, an acceleration period, a zero current period, and a deceleration period, and a fixed acceleration current and a deceleration current are sequentially determined. Feed-forward control for flowing to the lens actuator is performed.

  However, the acceleration characteristics and deceleration characteristics of the beam by the lens actuator vary for each optical disk drive. For this reason, if the acceleration current or the deceleration current is insufficient, the seek time is prolonged. On the other hand, if the acceleration current or the deceleration current is too large, the settling time is prolonged, so that there is a problem that sufficient one-track seek performance cannot be expected.

  Accordingly, an object of the present invention is to provide an optical storage device that improves seek performance by achieving both high-speed seek and shortening of settling time for each of normal seek control and one-track seek control.

  In addition, the present invention provides a control for moving a light beam to a target track mainly by a lens actuator, that is, a so-called track jump control. It is an object of the present invention to provide an optical storage device capable of being pulled into a track state.

  Further, in an optical disk drive using a replaceable medium such as a magneto-optical disk or a CD, the track eccentricity of the loaded medium is different for each medium, and the amount of eccentricity of the medium at the stage of initialization processing after loading is different. The eccentricity is measured, and an eccentric offset current is supplied to the VCM in synchronization with the rotation of the medium so as to cancel the measured eccentricity.

  When the track is regarded as a straight line, this medium eccentricity draws a sin curve. Therefore, a so-called eccentricity memory such as a RAM in which a sine value having a rotation angle of a predetermined resolution as an address is stored in advance is prepared, and the eccentricity information is used as the eccentricity information. From the measured amplitude and the phase with respect to the rotation reference position, the corresponding cosine value is read from the eccentric memory in synchronization with the actual medium rotation position to determine the amount of eccentricity, and an offset current is supplied so as to cancel the eccentricity.

  The measurement of the amount of eccentricity performed in the initialization processing after the conventional medium loading is obtained by one rotation of the medium in an on-track control state using a lens actuator, for example, using a lens position sensor that detects the position of an objective lens mounted on a carriage. The eccentric amplitude and phase are measured from the lens position signal.

  However, since the lens position sensor is originally used for the position servo of the lens lock for keeping the objective lens mounted on the carriage at the zero position (neutral position), the linearity and resolution of the detection signal with respect to the position are not so high. Since the signal is not high and the signal is an analog signal, an error occurs when AD conversion is performed, and there is a problem that highly reliable measurement of eccentricity information cannot be sufficiently performed.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an optical storage device that optimizes eccentricity correction by efficiently and accurately measuring eccentricity information required for eccentricity correction when loading a medium.

  In a conventional optical disk drive, return light from a medium is detected by a two-segment detector, and a tracking error signal is obtained from a difference between two light receiving signals. In this case, the ID portion of the medium records a zone number, a track number, and the like by embossing called a pit, the return light is attenuated by the pit of the ID portion, a noise-like drop variation appears in the tracking error signal, and the amplitude is reduced. In the low part, the zero crossing is erroneously made, and the counting of the number of tracks is erroneously performed.

  Therefore, in order to suppress the fluctuation due to the return light of the ID section, envelope detection is performed to smooth the profile of the tracking error signal.

  However, although there is no problem with a 540 MB or 640 MB MO cartridge medium for high-density recording, in the case of a conventionally used 128 MB MO cartridge medium, a mirror surface structure is provided between the ID part of the medium surface and the MO recording part. And in the case of a 230 MB MO cartridge medium, the mirror portion is similarly left in an area other than the user area.

  Therefore, when an MO cartridge from 128 MB to 640 MB can be used in one optical disk drive, when the 128 MB or 230 MB MO cartridge is loaded and the envelope detection is performed when the tracking error signal is generated, the same level is used. By taking the difference between the light receiving signals of the mirror sections having the above, the tracking error signal is lost in the mirror section. Further, signal loss corresponding to the discharge time constant due to the envelope detection is caused, and the tracking error signal is greatly distorted, so that the track count due to zero crossing is always erroneous.

  Further, regardless of the medium, if the envelope detection is performed, the peak level above and below the tracking error signal itself is detected by the envelope detection during high-speed seek in which the zero-crossing time interval of the tracking error signal is short. Also, there is a problem that the tracking error signal is lost.

  Accordingly, it is an object of the present invention to provide an optical storage device capable of appropriately generating a tracking error signal even with respect to the presence / absence of a mirror portion and high-speed seek due to a difference in medium.

  Further, the conventional optical disk drive is provided with a focus servo for performing focus control on the medium surface of the objective lens mounted on the carriage. The focus servo generates a focus error signal based on the light receiving output of the medium return light.

  However, since the ID portion on the track of the MO cartridge medium is a physical pit, the in-focus position of the objective lens differs with respect to the recording surfaces of the MO portions on both sides. The focus error signal changes in a stepwise manner at the boundary portion of, and unnecessary focus control is performed.

  For example, in the case of a 540 MB MO cartridge medium, the outer track has 84 sectors and the inner track has 54 sectors, and the ID portions corresponding to the number of sectors are provided. There is a problem that current consumption increases.

  Of course, it is sufficient to turn off the focus servo for the ID section. However, turning on and off the focus servo at high speed in conjunction with the ID section results in a large disturbance to the servo system, which impairs the autofocus function. Would.

Accordingly, an object of the present invention is to provide an optical storage device that eliminates useless movement of the focus servo by the ID unit without impairing the function of the focus servo.

  According to the present invention, the following effects can be obtained.

  According to the eccentricity correction of the optical storage device of the present invention, the eccentricity amplitude and the eccentricity phase are obtained from the zero cross of the tracking error signal of one rotation of the medium, and the eccentricity phase is correct or not from the measurement result at the time of the eccentricity correction based on the measured eccentricity information. The eccentricity correction can be optimized by immediately knowing the phase and measuring the eccentricity information with high accuracy.

According to the optical storage device of the present invention provided with the above-described track seek, fine seek, eccentricity correction, envelope servo, and focus servo, the seek performance for the target cylinder is greatly improved, and a replacement medium is used. Even if the optical disk drive is used, a storage capacity and access performance comparable to a hard disk drive can be achieved.

<Table of Contents>
1. 2. Device configuration 2.1 Track seek Fine seek 4. Eccentric memory control 5. Envelope servo 6. Focus servo

1. FIG. 2 is a circuit block diagram of an optical disk drive which is an optical storage device of the present invention. The optical disk drive of the present invention includes a controller 10 and an enclosure 12. The controller 10 includes an MPU 14 for overall control of the optical disk drive, an interface controller 16 for exchanging commands and data with a higher-level device, a formatter 18 for performing processing necessary for reading and writing data to and from the optical disk medium, and an MPU 14. , A buffer memory 20 shared by the interface controller 16 and the formatter 18.

  For the formatter 18, an encoder 22 and a laser diode control circuit 24 are provided as a write system, and the control output of the laser diode control circuit 24 is given to a laser diode 30 provided in the optical unit on the enclosure 12 side.

  In this embodiment, any one of 128 MB, 230 MB, 540 MB, and 640 MB can be used as an optical disk on which recording and reproduction is performed using the laser diode 30, that is, a rewritable MO cartridge medium. Of these, the 128 MB and 230 MB MO cartridge media employ pit position recording (PPM recording) for recording data in accordance with the presence or absence of a mark on the media.

  On the other hand, for 540 MB and 640 MB MO cartridge media for high-density recording, pulse width recording (PWM recording) in which the edges of the mark, ie, the leading edge and the trailing edge, correspond to data is adopted. Here, the difference between the storage capacities of 640 MB and 540 MB is due to the difference in sector capacity. When the sector capacity is 2 KB, the storage capacity is 640 MB, and when the sector capacity is 512 B, it is 540 MB.

  As described above, the optical disk drive of the present invention can support MO cartridges having a storage capacity of 128 MB, 230 MB, 540 MB or 640 MB. Therefore, when the MO cartridge is loaded into the optical disk drive, the interval between the ID portions of the medium is first measured from the signal indicating the presence of pits, the MPU 14 recognizes the type of the medium from the ID interval, and the type result is transmitted to the formatter 18. By giving the notification, the formatter processing corresponding to the PPM recording is performed for the 128 MB or 230 MB medium, and the formatter processing according to the PWM recording is performed for the 540 MB or 640 MB medium.

  As a read system for the formatter 18, a decoder 26 and a read LSI circuit 28 are provided. To the read LSI circuit 28, a light receiving signal of a return light of a beam from the laser diode 30 by the detector 32 provided in the enclosure 12 is input as an ID signal and an MO signal via a head amplifier 34.

  The read LSI circuit 28 has circuit functions such as an AGC circuit, a filter, a sector mark detection circuit, a synthesizer, and a PLL. The read LSI circuit 28 generates a read clock and read data from the input ID signal and MO signal, and outputs the read clock and read data to the decoder 26. I have. Since the zone CAV is adopted as a medium recording method by the spindle motor 40, the MPU 14 controls the switching of the clock frequency corresponding to the zone to the built-in synthesizer for the read LSI circuit 28.

  Here, the modulation method of the encoder 22 and the demodulation method of the decoder 26 are switched to the PPM recording modulation and demodulation method for 128 MB and 230 MB according to the medium type by the formatter 18. On the other hand, the medium of 540 and 640 MB is switched to the modulation and demodulation method of PWM recording.

  The detection signal of the temperature sensor 36 provided on the enclosure 12 side is given to the MPU 14. The MPU 14 controls the read, write and erase powers of the laser diode control circuit 24 to optimal values based on the environmental temperature inside the device detected by the temperature sensor 36. The MPU controls the spindle motor 40 provided on the head unit 12 side by the driver 38.

  Since recording and reproduction of the MO cartridge is performed in the zone CAV, the spindle motor 40 is rotated at a constant speed of, for example, 3600 rpm. The MPU 14 controls an electromagnet 44 provided on the head unit 12 via a driver 42. The electromagnet 44 is arranged on the side opposite to the beam irradiation side of the MO cartridge loaded in the apparatus, and supplies an external magnetic field to the medium during recording and erasing.

  The DSP 15 implements a servo function for positioning the beam from the laser diode 30 with respect to the medium. For this reason, the optical unit on the enclosure 12 side is provided with a two-segment detector 46 for receiving the beam mode light from the medium, and the FES detection circuit (focus error signal detection circuit) 48 detects the focus error from the light reception output of the two-segment detector 46. The signal E1 is created and input to the DSP 15.

  A TES detection circuit (tracking error signal detection circuit) 50 creates a tracking error signal E2 from the light receiving output of the two-segment detector 46 and inputs the tracking error signal E2 to the DSP 15. The tracking error signal E2 is input to a TZC circuit (track zero cross detection circuit) 45, generates a track zero cross pulse E3, and inputs it to the DSP 15.

  Further, on the enclosure 12 side, a lens position sensor 52 for detecting a lens position of an objective lens for irradiating the medium with a laser beam is provided, and a lens position detection signal (LPOS) E4 is input to the DSP 15. The DSP 15 controls and drives the focus actuator 56, the lens actuator 60, and the VCM 64 via drivers 54, 58, and 62 for beam positioning.

  Here, the outline of the enclosure in the optical disk drive is as shown in FIG. In FIG. 3, a spindle motor 40 is provided in a housing 66, and the MO cartridge 72 inside the spindle motor 40 is inserted into the hub of the rotation shaft of the spindle motor 40 from the inlet door 68 side. Loading to be mounted on the hub of the rotating shaft is performed.

  A carriage 76 is provided below the MO medium 72 of the loaded MO cartridge 70 so as to be movable in a direction traversing the medium track by the VCM 64. An objective lens 80 is mounted on the carriage 76, and a beam from a semiconductor laser provided in the fixed optical system 78 is incident via a prism 81 to form a beam spot on the medium surface of the MO medium 72.

  The movement of the objective lens 80 in the optical axis direction is controlled by the focus actuator 56 shown in the head unit 12 in FIG. 2, and the objective lens 80 can be moved in the radial direction across the medium track within a range of, for example, several tens of tracks by the lens actuator 60. . The position of the objective lens 80 mounted on the carriage 76 is detected by the lens position sensor 52 in FIG. The lens position sensor 52 sets the lens position detection signal to 0 at a neutral position where the optical axis of the objective lens 80 is directed directly above, and a lens according to the amount of movement of different polarities for movement toward the outer side and movement toward the inner side. It outputs the position detection signal E4.

  The optical disk drive of the present invention may use a read-only CD as an optical disk medium other than the MO cartridge. FIG. 4 shows a state where a CD is loaded instead of the MO cartridge 70 of FIG. In the case of using a CD, in this embodiment, the CD medium 82 is mounted on a tray 84 prepared in advance, and is loaded into the housing 66 from the inlet door 68.

  The tray 84 is provided with a turntable 86 for mounting a CD medium 82 on the spindle motor 40 in advance. For this reason, the CD medium 82 is mounted on the tray 84 with the central hole of the CD medium 82 fitted in the turntable 86, and is loaded on the optical disk drive.

  As the turntable 86 used for the tray 84, the CD medium 82 has the same CD mounting structure as a normal CD disk drive corresponding to the center hole of the CD medium 82, and the spindle motor 40 side of the turntable 86 has The same hub structure as that used for the MO cartridge 70 in FIG. 3 is used. By using such a turntable 86, even if the CD medium 82 is an exposed medium having a completely different shape and size, it can be loaded onto the spindle motor 40 in the same manner as the MO cartridge 70 using the tray 84. Can be.

  In order to cope with the loading of the CD medium 82, the controller 10 shown in FIG. 2 recognizes that the medium loaded by the MPU 14 is the CD medium 82, and the formatter 18 and the read LSI circuit 28 And switch the decoder 26 to a circuit function corresponding to the CD.

  Alternatively, a read system circuit dedicated to a CD medium may be provided to switch from the read system of the MO cartridge to the read system of the CD medium. At the same time, the MPU 14 controls the medium rotation control by the spindle motor 40 in the CD medium 82 according to the constant linear velocity method (CLV method), so that the read clock obtained from the CD read system is equal to the reference constant linear velocity. In order to achieve this, the spindle motor 40 is controlled via the driver 38 by CLV control that changes the number of revolutions according to the track position.

  Of course, the present invention may be an optical disk drive dedicated to the MO cartridge 70 shown in FIG. 3 which does not have the function of reproducing the CD medium 82 as shown in FIG.

  FIG. 5 is a functional block diagram of focus servo, lens servo, and VCM servo realized by the DSP 15 provided in the controller 10 of FIG. First, the focus servo system converts the focus error signal E1 into digital data by the AD converter 88 and takes it in. The digital signal is corrected at the addition point 90 by the FES offset set in the register 92, and the phase compensator 94 sets the gain for a predetermined high band. The PID calculator 96 performs a proportional-integral-derivative calculation on the focus error signal.

  Further, after performing phase compensation by the phase compensator 100, the focus offset of the register 102 is compensated at the addition point 104, converted into an analog signal by the DA converter 108 via the limiter 106, and a current instruction value is output to the focus actuator 56. ing. A servo switch 98 is provided between the PID calculator 96 and the phase compensator 100 to control the on / off of the focus servo.

  Next, a lens servo system for the lens actuator 60 will be described. The lens servo system is divided into three groups: a speed control system, a track servo system, and a lens position servo system. First, the speed control system inputs the track zero cross signal E3 to the counter 110, obtains the time of the track zero cross interval by clock count, and obtains the beam speed by the speed calculator 112.

  The output of the speed calculator 112 has a deviation from the target speed from the register 116 at an addition point 114, and the phase compensator 120 performs a phase compensation for the speed deviation via a servo switch 118. Has been given to.

  The track servo system of the lens servo converts the tracking error signal E2 into digital data by the AD converter 124, takes in the data, corrects the TES offset set by the register 126 at the addition point 128, and compensates the phase by the phase compensator 130. After performing the PID operation, the PID operation unit 140 performs a proportional integral and a differential operation, and then inputs the result to the adder 122 via the servo switch 142.

  Further, as a lens position servo system, a lens position detection signal E4 is fetched as digital data by an AD converter 144, an LPOS offset is corrected by a register 148 by an adder 146, and a phase compensator 150 is phase-compensated. At 152, a proportional-integral-differential operation is performed, and is input to the adder 122 via the servo switch 156. Note that TES offset cancellation can be added to the input side of the servo switch 156 by the register 154.

  The speed deviation signal of the speed servo system, the tracking error signal of the tracking servo system, and the lens position deviation signal of the lens position servo system are added by the adder 122 and subjected to phase compensation by the phase compensator 158. After the track offset is corrected by the register 162 at the addition point 160, the signal is converted into an analog signal by the DA converter 166, and is output to the driver as a current instruction value for the lens actuator 60.

  Next, the servo system of the VCM 64 will be described. The servo system of the VCM 64 constitutes a feed-forward control servo system based on the deviation between the target track position during seek and the current track position. First, the current position of the beam detected by the counter 110 based on the track zero cross signal E3 by the register 168 is compared with a target track position of the register 172 by an adder 170, and a position deviation signal corresponding to the number of remaining tracks with respect to the target track position is obtained. Is generated.

  The output of the adder 170 is subjected to phase compensation by a phase compensator 174, then subjected to proportional, integral and differential operations by a PID calculator 176, and further subjected to phase compensation by a phase compensator 180 via a servo switch 178. The signal is supplied to the IIR 188 via the adder 182, and further subjected to phase compensation by the phase compensator 190. Then, the adder 192 receives correction by the VCM offset by the register 194, and provides the signal to the adder 198 via the limit 196. Can be

  The adder 198 corrects the eccentricity of the medium by reading from the eccentricity memory 200. With respect to the position error signal of the VCM servo having undergone the eccentricity correction by the adder 198, different polarities are set by the register 202 according to the seek in the inner direction and the seek in the outer direction. The data is converted into an analog signal by the DA converter 206, converted into a VCM current instruction value by the VCM 64, and output to the driver side.

  Further, to the adder 182 of the VCM servo system, the output of the phase compensator 150 of the lens position servo system provided in the lens servo system is branched and input via the PID calculator 184 and the servo switch 186. . Therefore, when the objective lens is driven by the lens actuator 60 and the lens seek is performed while the servo switch 186 is on, the lens position deviation signal generated by the adder 146 based on the lens position detection signal at this time is converted to a PID calculator. 184 and a servo switch 186 are applied to an adder 182 of the VCM position servo system as a position deviation signal.

  Therefore, the VCM 64 controls the position of the carriage by driving the lens actuator 60 so that the lens position offset becomes zero. Since the servo control based on the deviation signal of the lens position detection signal by the lens actuator is added to the servo system of the VCM 64, this is called double servo.

  FIG. 6 shows the control mode and the on / off states of the servo switches 98, 118, 142, 156, 178 and 186 in the servo system of FIG. The control modes of the servo system are divided into five modes: a focus-off mode, a track-off mode, a track-on mode, a fine seek mode, and a position seek mode.

  The control contents of each mode are as shown in FIG. First, in the focus-off mode, the track access of the beam is stopped. The focus servo is turned off by turning off the servo switch 98, and the objective actuator on the carriage is set to zero by the lens actuator 60 by turning on only the servo switch 156. The position is controlled.

  In the track-off mode, focus servo is enabled by turning on the servo switch 98, and the servo switch 156 is turned on to control the objective lens to the zero position by the lens actuator 60. For this reason, in the track-off mode, only focusing of the beam on the medium can be performed with the beam stopped.

  In the track-on mode, the servo switch 98 is turned on to enable focus servo, and the servo switch 142 is turned on to perform on-track control by driving the lens actuator 60 by a tracking error signal. Further, by turning on the servo switch 186, the VCM servo system is subjected to position servo based on the lens position detection signal, so that the VCM offset and the eccentric offset can be compensated.

  The fine seek mode is control for moving a beam to a target position by speed control of the lens actuator 60 and feedforward control of the VCM 64 when an instruction to access the target cylinder is issued from the host device. That is, the speed control of the lens actuator 60 is performed by turning on the servo switch 118 in a state where the focus servo is enabled by turning on the servo switch 98.

  Further, when the servo switch 178 is turned on, feedforward control is performed according to the deviation of the current track position from the target track. Further, by turning on the servo switch 186, a double servo for controlling to the lens 0 position by driving the VCM 64 based on the positional deviation of the lens position signal E4 is applied.

  The position seek mode is a lens position control by the lens actuator 60. In a state where the lens is held at the zero position, the beam is moved to the target track by the VCM 64 using a position deviation signal corresponding to the number of tracks at the current track position with respect to the target track position. Position control.

  In other words, the servo switch 156 is turned on with the focus servo enabled by turning on the servo switch 98, and the lens actuator 60 locks the lens at the zero position. In this state, when the servo switch 178 is turned on, the carriage is moved by the VCM 64 so that the deviation from the target track position becomes zero, and the beam is position-controlled on the target track.

2.1 Track seek control FIG. 8 shows the tracking error signal E2 and the lens actuator in the seek control when a one-track seek command is received from a higher-level device to set a track adjacent to the current track on the inner or outer side as a target track. 6 shows a time chart of a DA converter to be driven, an instruction current value I2, and a control state of a track-on mode.

  In the one-track seek control in the optical disk drive of the present invention, the seek control period is divided into three periods of an acceleration period 210, a pre-deceleration period 212, and a deceleration period 214, as indicated by a tracking error signal E2 in FIG. Further, the difference between the value TES1 of the sampling point 216 of the tracking error signal E2 at the time t2 when the acceleration period 210 ends and the value TES2 of the sampling point 220 of the tracking error signal E2 at the time t4 when the deceleration period 214 starts is beamed. It is obtained as information indicating the moving speed. The value Ib2 of the deceleration current in the deceleration period 214 in FIG. 8B is determined from the difference (TES1-TES2) between the two sample points 216 and 220, so that on-track can be stably performed with one track seek.

  An acceleration period 210, a pre-deceleration period 212, and a deceleration period 214 in one track seek period of the DAC instruction current value I2 in FIG. The deceleration time T2 and the deceleration time T3 are each fixedly set. In this embodiment, assuming that the number of samplings of the DA converter that takes in the tracking error signal E2 is in units of one hour, the acceleration time T1 is set for a 540 MB and 640 MB MO cartridge medium of high-density recording with a track pitch of 1.1 μm. 7 are obtained as the optimum values, the pre-deceleration time T2 is obtained as 2 samples, and the deceleration time T3 is obtained as 4 samples.

  That is, in the one-track seek control according to the present invention, seven samples are allocated out of a period in which the first acceleration period 210 has a total of 13 samples, and a period exceeding half of the one-track seek period is defined as the acceleration period 210. By passing a predetermined acceleration current Ia during this acceleration period, sufficient acceleration is performed even for one track seek. This number of samples is obtained when the sampling frequency of the AD converter 124 in FIG. 5 is 68 KHz.

  On the other hand, the acceleration period, the zero-speed period corresponding to the pre-deceleration period, and the deceleration period in the conventional one-track seek control are approximately one-third, and even when the same acceleration current Ia is used, the acceleration period is conventionally the whole. , The beam acceleration is lower than that of the one-track seek of the present invention. Therefore, in the one-track seek of the present invention, the acceleration of the beam moving speed is sufficiently accelerated by performing the acceleration period 210 for a period of more than 1/3 of the conventional case, and actually for more than half the time T1 = 7 samples. Thus, the seek time for one track is reduced.

  In the next pre-deceleration period 212, preliminary deceleration is performed prior to the last deceleration period 214. In this case, the value of the deceleration current Ib used for the pre-deceleration 212 may be determined by multiplying the acceleration current Ia by a predetermined coefficient of 1 or less. According to an experiment conducted by the inventors of the present application, optimal one-track control was performed when a half of the acceleration current was used as the pre-deceleration current Ib1. Therefore, it is desirable to use a value near half of the acceleration current Ia as the pre-deceleration current Ib1 used in the pre-deceleration period 212.

Regarding the deceleration current Ib2 in the deceleration period 214 following the pre-deceleration period 212, the difference between the values TES1 and TES2 of the tracking error signal E2 detected at the sample points 216 and 220 at the acceleration end time t2 and the deceleration start time t4, respectively ( From the TES1-TES2) and the pre-deceleration time T2, the speed V is calculated as V = (TES1-TES2) / T2
Asking. Based on the speed V obtained from the actual change of the tracking error signal E2, the deceleration current Ib2 is calculated as follows: Ib2 = (T3 / V) × Brake Gain Gb
By flowing the lens through the lens actuator over the deceleration time T3, it is possible to stably turn on the track at the end of one track seek.

  In the control state of the track-on mode shown in FIG. 8C, the track servo is turned off at the start of the one-track seek control at the time t1, and the track servo is turned on at the end of the deceleration at the time t6. At t6, the beam can be stably turned on the target track one track ahead.

  As described above, in the one-track seek control of the present invention, the actual speed is detected from the tracking error signal E2 in the one-track seek control to determine the value of the deceleration current Ib2 during the deceleration period. Even if the speed fluctuates, the optimum deceleration current Ib2 depending on the speed at that time can be specified, and as a result, a stable one-track seek on-track can be realized even if the optical disk drive differs.

  FIG. 9 is a flowchart of a control process for realizing the one-track seek control of the present invention shown in FIG. 8. When a one-track seek command is decoded from the upper device to the MPU 14 in FIG. This is executed by instructing one track seek.

  In FIG. 9, first, at step S0, a TES sensitivity correction value for normalizing the upper and lower peak values of the tracking error signal E2 to a constant value is set. The correction value of the TES sensitivity normalization is obtained by taking in a tracking error signal by slowly moving a beam at a constant speed by a VCM or a lens actuator during an initialization process when an MO cartridge is loaded into an optical disk drive, and taking in a tracking error signal. The amplitude value is measured, and a correction value is obtained from the ratio of the measured amplitude value to a predetermined standard amplitude value.

  For example, when the standard value of the vertical amplitude is Aref and the difference between the actually measured upper and lower peak values is A, the correction value α of the TES sensitivity for normalizing the actually obtained tracking error signal to the standard value is α = ( Aref / A). The correction value α for normalizing the TES sensitivity obtained in the initialization processing at the time of loading the medium is fetched in step S0, and the correction value is always obtained when the tracking error signal is fetched in the following one-track seek processing. The value normalized by multiplying by α is used.

  Subsequently, in step S1, a current instruction value is output to an AD converter for supplying the acceleration current Ia to the lens actuator. Thereby, the lens actuator 60 accelerates and moves the beam toward the adjacent track. In step S2, the elapse of a predetermined acceleration time T1 is determined. When the acceleration time T1 elapses, the tracking error signal TES at that time is sampled in step S3 to be TES1. Of course, the TES 1 is corrected by multiplying by the correction coefficient α for normalizing the TES sensitivity.

  Next, in step S4, for example, a pre-deceleration current Ia / 2 that is half of the acceleration current Ia is supplied to the lens actuator to instruct a current output for performing pre-deceleration. In this pre-deceleration state, the elapse of a predetermined pre-deceleration time T2 is determined in step S5. After elapse of T2, the tracking error signal E2 is sampled again in step S6 to be TES2.

  Subsequently, in step S7, the speed V is obtained from the values TES1 and TES2 of the tracking error signals captured in steps S3 and S6 using a predetermined pre-deceleration time T2. Subsequently, in step S8, it is checked whether or not the absolute value of the speed V obtained in step S7 is equal to or higher than a predetermined maximum speed Vmax. If the speed exceeds the maximum speed Vmax, the process proceeds to step S9, where it is determined that abnormal acceleration due to vibration, inclination of the optical disk drive, or the like has been applied, and in this case, the speed V is fixed to the maximum speed Vmax.

  On the other hand, if the absolute value of the speed V is smaller than the maximum speed Vmax in step S8, the process proceeds to step S10, where the absolute value of the speed V is compared with a predetermined minimum speed Vmin. In this case, when the speed is smaller than the minimum speed Vmin, it is determined that an erroneous speed is calculated by fetching an erroneous tracking error signal due to a factor such as vibration at the timing when fetching in step S3 or step S6. Judgment is made, and the speed V is fixed to the minimum speed Vmin in step S11.

  When the speed V is determined in this manner, the deceleration time T3 is divided by the obtained speed V in step S12 and multiplied by the brake gain Gb to obtain the deceleration current Ib2. The output of the deceleration current Ib2 is instructed. Subsequently, the elapse of a predetermined deceleration time T3 is checked in step S3. When the deceleration time T3 elapses, the output of the deceleration current to the lens actuator is turned off in step S14.

  In step S15, the control of the on-track mode, which was in the off state for on-track control, is turned on, whereby the beam is drawn into the adjacent track. Then, in step S16, the on-track settling conditions, for example, predetermined for the track center are determined. When the on-track completion is recognized by the MPU 14 when it is recognized that the data is within the offset range, the series of one-track seek control ends.

  In the on-track control state after the end of the one-track seek control, the MPU 14 records or reproduces data on the medium track in accordance with the access command transferred following the one-track seek command of the host device.

  Here, the optimum number of samples of the acceleration time T1 of the acceleration period 210, the pre-deceleration time T2 of the pre-deceleration period 212, and the deceleration time T3 of the deceleration period 214 in the one-track seek control of FIG. This is a case where the sampling frequency of the AD converter 124 shown in FIG. In the case of a sampling frequency of 68 KHz, the time of one sample is about 15 μs, the time of one sample is about 195 μs for 13 samples, and the on-track of one track seek is a short time of 250 μs to 300 μs including the settling time from time t5 to t6. It can be performed.

  Further, in the one-track seek control of the present invention, for example, when the number of tracks to the target cylinder is smaller than a predetermined value, for example, in the case of several tracks, the one-track seek control of FIG. 8 is repeated by the number of tracks to the target track. Seek. Specifically, the processing at times t1 to t6 is repeated for each track. For a seek exceeding the number of tracks to the target track by repeating this one-track seek control, seek control according to the fine seek mode in FIG. 7 is performed.

3. In FIG. 2, the MPU 14 recognizes that the optical disk drive of the present invention has received the access command from the host device via the interface controller 16 to the target track whose number of tracks exceeds one-track seek control. Indicates a fine seek with an address specified.

  Upon receiving the fine seek command from the MPU 14, the DSP 15 performs the fine seek control as shown in the time chart of FIG. This fine seek control is a control mainly using the lens actuator 60 for moving the objective lens 80 mounted on the carriage 76 shown in FIG. 3, and at the same time, a control using the VCM 64 for driving the carriage 76 as a sub.

  In the fine seek control of FIG. 10, a tracking error signal E2 from a seek start to a seek end, a beam speed V, a current I2 of the lens actuator 60, and a current I3 of the VCM 64 are shown. In the seek control of the lens actuator 60, speed control for controlling the target speed based on the number of remaining tracks from the current track to the target track is performed.

  This speed control is, as shown in FIG. 10B, an acceleration section 230, a constant speed section 232, and a deceleration section 240 following the constant speed section 238 immediately before the target cylinder. On the other hand, the carriage control by the VCM 64 generates an acceleration current and a deceleration current according to the positional deviation of the deceleration track with respect to the target track at the start of the seek as shown in FIG. Subsequently, feedforward control for deceleration is performed.

  Specifically, the acceleration current 246 flows as the VCM current I3 in the first half of the seek control, and the deceleration current 248 flows in the latter half of the seek control. By the constant acceleration control by the feed forward control of the VCM 64, the beam velocity V of FIG. 10B has a constant acceleration section 234 by the feed forward control of the VCM in the middle of the constant acceleration section 232 by the speed control of the lens actuator.

  When the beam passes a half position to the target track, a constant deceleration section 236 due to the deceleration current of the feedforward control of the VCM 64 is formed. Below the speed, a constant speed section 238 appears.

  Looking at the speed control by the lens actuator 60 in detail, first, a specified acceleration current 242 is supplied to the lens actuator 60 at the start of seek at time t1. This acceleration current has a current value Ia and is supplied for a predetermined time T1. Thus, the lens actuator 60 is accelerated at a predetermined constant speed. When the acceleration is completed at time t3, thereafter, the constant speed control is performed to maintain the constant speed so as to reach the target speed.

  After the zero-cross point 250 immediately before the target track of the tracking error signal E2 in FIG. 10A, the difference (TES1-TE2) between the values TES1 and TES2 of the tracking error signal E2 obtained at the sample points 248 and 252 before and after the target track. A deceleration current 244 based on TES2) is passed from time t8 to time t9, and at the end of deceleration at time t9, the on-track servo is enabled and the beam is on-tracked to the target cylinder.

  On the other hand, in the control of the VCM 64 shown in FIG. 10D, acceleration is performed at time t2 when a zero-cross count start time Tcs has elapsed from the start of seek at time t1 to immediately before the zero-cross point of the first tracking error signal E2 is obtained. Feed-forward current -Iff is supplied to the VCM 64 to perform acceleration control toward the target cylinder. When the beam reaches a half track position up to the target cylinder at time t4 by counting the zero crossing of the tracking error signal E2, at this time, the current is switched to the deceleration current Iff, and deceleration control of constant acceleration is performed. Then, the deceleration current of the VCM 64 is turned off at the time t6 when the zero cross point 250 at the 0.5 track position immediately before the target track is reached, and the feedforward control is terminated.

  Here, the tracking error signal E2 in FIG. 10A is a tracking error signal in a fine seek when the MO cartridge is loaded. For the MO cartridge medium, a zero cross point of the tracking error signal E2 is obtained at an adjacent track boundary. Therefore, the track position of the zero cross has a scale of 0.5, 1.5, 2.5,....

  FIG. 11 shows details of the deceleration control by extracting the tracking error signal E2 and the beam speed V for the constant speed section 238 and the deceleration section 240 immediately before the target track in FIG.

  In the deceleration control immediately before the target track in the fine seek according to the present invention, the tracking error signal E2 is detected at each of the sample points 248 and 252 before and after the zero cross point 250 which is 0.5 track before the zero cross point just before the target track. Of the deceleration current flowing through the lens actuator 60 shown in FIG. 11B from the time t7 at the sampling point 252 to the start of deceleration based on the difference (TES1-TES2) between the two values. The time T1, the deceleration time T2, and the deceleration current Ib are determined.

That is, since the difference (TES1-TES2) between the tracking error signals E2 at the sample points 248 and 252 is the beam movement amount in the sample period Ts, the beam speed V is
V = (TES1-TES2) / Ts
It becomes. Therefore, in the deceleration control according to the present invention, the deceleration current Ib flowing during the fixed deceleration time T2 is determined based on the beam speed V. That is, the deceleration current Ib is
Ib = (T2 / V) × Brake gain Gb
It becomes. Such deceleration control based on the determination of the deceleration current Ib according to the beam speed V is effective when the beam speed before the start of deceleration is within the limit speed that can be pulled into the on-track state. Therefore, in order to determine the beam speed at the start of deceleration, according to the present invention, the time T0 between the immediately preceding zero-cross point 254 and the immediately preceding zero-cross point 250 with respect to the target track in FIG. The time T0 from 1.5 track to 0.5 track before the track is measured, and the deceleration start speed V0 is thereby determined.
V0 = (2 × track pitch TP) / T0
Asking. If the deceleration start speed V0 obtained in this way is within the limit speed at which on-track retraction is possible, the deceleration start time T1 in FIG.
T1 = T0 / 256
To decide. Here, the denominator 256 is a predetermined default value, and an appropriate value can be used as needed. Then, at the timing when the deceleration start time T1 has elapsed, the deceleration current is obtained from the speed V, the deceleration time T2, and the brake gain Gb obtained from the difference (TES1-TES2) between the sample points 248, 252 before and after the zero cross point 250 immediately before the target track. Ib is determined and flowed over a fixed deceleration time T2.

On the other hand, if the deceleration start speed V0 obtained based on the time T0 from the 1.5 track to the 0.5 track exceeds the limit speed at which the on-track retraction is possible, the deceleration start speed V0 is too high. In this case, the deceleration current Ib is not determined by the beam speed V in accordance with the difference (TES1-TES2) between the sample points 248 and 252 before and after the zero cross point 250 immediately before the target track, and the deceleration start time T1 is set to T1 = 0. The deceleration current Ib is a predetermined deceleration maximum current value Imax, and the deceleration time T2 is
T2 = (2 × track pitch TP) / T0
Determined by In the case of the overspeed as described above, by flowing the maximum deceleration current Imax over the deceleration time T2, it is possible to surely decelerate to a speed near zero which can be stably drawn into the target track.

  12 and 13 are flowcharts of the fine seek control of FIG. 10. The deceleration control immediately before the target track is separately shown in detail in FIGS. 14 and 15. FIG. 12 shows the main control of the lens actuator 60 in the fine seek control. First, in step S1, an acceleration current Ia is output to the lens actuator 60 as shown in FIG. Subsequently, as shown in FIG. 10D, the elapse of a predetermined track zero cross count start time Tcs is checked in step S2, and if this elapse is determined, the elapse of the actuator acceleration time Ta is checked in step S3.

  Until the actuator acceleration time Ta elapses, it is checked in step S4 whether or not the first track zero-cross is detected. When the track zero-cross is detected, the process proceeds to step S5, and the first TZC detection flag is set. . When the actuator acceleration time Ta has elapsed in step S3, it is checked in step S6 whether the first TZC detection flag in step S5 has been set. If set, the process proceeds to step S8. If it has not been set, that is, if the first tracking zero cross has not been detected, it is checked in step S7 whether a track zero cross has been detected. If a zero crossing of the track is detected, the process proceeds to step S8.

  In the detection of the first track zero-cross in steps S4 to S7, when the beam speed is obtained from the time lapse of the zero-cross point of the tracking error signal E2, the speed cannot be detected at the first zero-cross point at the start of the seek, and the second time. Since it is obtained for the first time, this is a process for skipping the first zero-cross detection from the speed calculation target.

  Then, when the second track zero cross detection from the start of the seek is performed in step S8, the beam speed is obtained from the time interval of the two zero crosses for the first time, and the actuator speed control from step S9 can be performed. Therefore, when the second track zero cross detection is performed in step S8, the beam is located at a position shifted from the seek start position to the 1.5 track target cylinder side.

  In step S9, a time interval between the previous track zero cross and the current track zero cross is obtained and compared with a predetermined time φ2 corresponding to a predetermined hardware failure of the lens actuator. If the time exceeds the abnormal time φ2, error processing is performed in step S10. If the time interval of the track zero cross is normal, the process proceeds to step S11, and it is determined whether the number of remaining tracks for the target track has reached 1.5 tracks.

  Until the track reaches 1.5 tracks before the target track, the speed control processing from step S12 is performed. In step S12, it is checked whether the seek direction is the inner direction. If it is the inner direction, the process proceeds to step S13, and the VCM 64 outputs the feed forward current for the inner seek. If it is on the outer side, the feed forward current for outer seek is output to the VCM 64 in step S14. Subsequently, in step S15, the target speed is calculated from the number of tracks remaining from the current track to the target track, and it is determined in step S16 in FIG. 13 whether the target speed is the maximum target speed VTmax.

  If the target speed is equal to or higher than the maximum target speed VTmax, the target speed is set to the maximum target speed VTmax in step S13, and the current to the VCM 64 is determined so as to have a constant acceleration φ1 corresponding to the target speed. If the calculated target speed is equal to or less than the maximum target speed VTmax, the process of step S17 is not performed. Subsequently, in step S18, a value obtained by dividing the actual speed, that is, the track pitch TP by the track zero-cross interval from the target speed, is multiplied by a predetermined speed feedback gain Gv, and the current I2 is output to the lens actuator 60.

  When the number of remaining tracks becomes 1.5 tracks in step S11 in FIG. 12, deceleration control in step S19 is performed. The deceleration control in step S19 is shown in detail in FIGS.

  In the deceleration control of FIG. 14, when the vehicle reaches 1.5 tracks before the target track, the control conditions of the speed control are changed in step S2 to perform pre-deceleration. This pre-deceleration lowers the feedback gain Gv of the speed control and sets the target speed to zero. In order to lower the feedback gain Gv, a correction coefficient K is specifically multiplied.

  As the correction coefficient K, K = 0.5 was optimal experimentally. By setting the target speed to 0 and reducing the feedback gain Gv to half, the value of (track pitch TP) / (TZC time interval), which is the beam speed at that time, has a negative value, and the speed feedback gain The pre-deceleration current 256 multiplied by a value obtained by halving Gv is supplied to the lens actuator 60 from the position of 1.5 cylinders before the target track as shown in FIG. By such pre-deceleration control before the deceleration control of the target cylinder in step S20, the beam speed can be controlled to the optimum deceleration start speed.

  Subsequently, in step S21, it is checked whether the number of remaining tracks has reached 0.5 tracks. Until the remaining track reaches 0.5 track, every time the sampling TES of the tracking error signal E2 is obtained in step S22, this is taken in as TES1 used for calculating the speed proportional value. When the number of remaining tracks reaches 0.5 tracks in step S21, it is checked in step S23 whether the deceleration start speed V0 from 1.5 tracks to 0.5 tracks exceeds the limit speed Vth.

  Specifically, a threshold time Tth = 100 μs corresponding to the limit speed Vth is set, and if the TZD time interval T0 from 1.5 tracks to 0.5 track is 100 μs or less, it is determined that the speed exceeds the limit speed. Then, the process proceeds to the processing for speed over in step S36 and subsequent steps. If the TZC time interval T0 is 100 μs or more, it is determined that the vehicle is at an appropriate deceleration start speed. In step S24, the first sampling timing after 0.5 tracks has elapsed is determined in step S24. At step S25, the tracking error signal TES is fetched and set as TES2.

  Then, in step S26, the deceleration start time T1 is calculated using the TZC time interval T0 and the default value 256, and in step S27, the elapse of the deceleration start time T1 is checked. If the deceleration start time T1 has elapsed, it is checked in step S28 whether the beam speed V is equal to or higher than a predetermined maximum speed Vmax. If it exceeds the maximum speed Vmax, a maximum deceleration current Imax is output over a fixed deceleration time T2 in step S31.

  If it is equal to or lower than the maximum speed Vmax, it is checked in step S29 whether it is equal to or lower than the minimum speed Vmin. If the speed is equal to or lower than the minimum speed Vmin, the minimum deceleration current Imin is output over a fixed deceleration time T2 in step S32. If the beam speed V obtained by (TES1-TES2) is in an appropriate range between the maximum speed Vmax and the minimum speed Vmin, the deceleration current Ib is determined from the sample period Ts, the beam speed V, and the brake gain Gb in step S30 to be constant. It flows over the deceleration time T2.

  If the deceleration current has been output to the lens actuator in step S30, S31 or S32, the flow proceeds to step S33 in FIG. 15, and the elapse of the deceleration time T2 is checked. That is, the mode is switched to the track-on mode shown in FIGS. 6 and 7, the target track is pulled in, and when the on-track stabilization check is obtained in step S35, a series of processing ends.

On the other hand, in step S23 of FIG. 14, the TZC time interval T0 from 1.5 track to 0.5 track is smaller than the limit time Tth = 100 μs corresponding to the limit speed Vth, and the deceleration start speed exceeds the limit speed Vth. When it is determined that this is the case, the process proceeds to step S36, where the deceleration start time T1 is set to T1 = 0, and the deceleration time T2 is set to
T2 = (2 × track pitch TP / T0)
Asking. The calculation of the deceleration time T2 is as follows: Assuming that the deceleration acceleration is A and the deceleration start speed is V, T2 = V / A
It means that it becomes. Subsequently, in step S37, a predetermined maximum deceleration current Imax is output, and the elapse of the deceleration time T2 calculated in step S36 is checked. When the elapse of the deceleration time T2, the process proceeds to step S34 in FIG. Then, the process ends with an on-track settling check in step S35.

  FIG. 16 is a time chart of the deceleration control immediately before the target track of the fine seek control when the CD medium 82 is loaded into the optical disk drive of the present invention as shown in FIG. 5 shows a tracking error signal E20 and a current I2 flowing to the lens actuator 60 at that time. In the case of a CD medium, the tracking error signal E20 crosses zero at the track center. Therefore, the zero-cross point of the tracking error signal in the case of a CD medium represents the number of tracks of 0, 1, 2, 3,...

  Therefore, in the deceleration control immediately before the target track on the CD medium, as shown in FIG. 16A, the deceleration start speed V0 is set from the TZC time interval T0 of the zero cross points 400 and 402 of one track from two tracks before the target track. Assuming that the values of the tracking error signals E20 at the sample points 404 and 406 before and after the zero-cross point 402 one track before the target track are TES1 and TES2, the beam velocity V is obtained from the difference (TES1-TES2). Other points are the same as those of the MO cartridge medium of FIG.

  Of course, the track pitch TP in the CD medium uses 1.6 μs unique to the CD. In the case of the MO cartridge medium, the track pitch TP is 1.1 μs for 540 MB and 640 MB, 1.4 μs for 230 MB, and 1.6 μS for 128 MB, like the CD medium. Therefore, in response to the recognition result of the medium type when the MO cartridge or the CD is loaded, the track pitch corresponding to the medium type and the scale setting of the number of tracks according to the MO cartridge medium or the CD medium may be set.

  Of course, the tracking error signal values TES1 and TES2 used in the deceleration control should be used after performing sensitivity correction by multiplying by a correction value for normalizing the tracking error signal obtained in the medium loading initialization process. Of course.

4. Correction of Eccentricity FIG. 17 is a functional block for measuring the amount of eccentricity of the medium in the initialization process after loading the optical disk medium provided in the optical disk drive of FIG. 2 and performing eccentricity correction based on the measurement result.

  In FIG. 17, an eccentricity measuring unit 260 is provided on the MPU 10 side for eccentricity correction. Further, an eccentricity memory control unit 262 is provided on the DSP 15 side, and based on the measurement result of the eccentricity information by the eccentricity measuring unit 260 of the MPU 10, offset correction for correcting the amount of eccentricity for the servo system of the VCM 64 using the eccentricity memory 200 Perform

  Specifically, the eccentric offset amount created based on the eccentric memory 200 is given to the adder 198 at the output stage of the limit 196 in the servo system of the VCM 64 shown in FIG. An eccentric offset is added to the current instruction value so as to offset the eccentric amount.

  First, the measurement processing of the eccentricity measurement unit 260 provided in the MPU 10 will be described. FIG. 18 shows the MO cartridge medium 70 loaded into the optical disk drive of the present invention. The MO cartridge medium 70 has a hub mounted on the spindle motor rotation shaft at the center of the medium, and the track center 266 formed on the medium surface with respect to the rotation center 264 of the hub usually has an eccentricity of about several tens of microns. ing.

  For this reason, when the MO cartridge medium 70 is loaded and mounted on the rotation center 264 of the spindle motor, an eccentric amount is generated on the track in which one rotation corresponds to one cycle corresponding to the eccentric amount with the track center 266.

  Here, the recording area of the disk surface of the MO cartridge medium 70 is radially divided into ten zones from the innermost zone 0 to the outermost zone 9. Each zone is a repetition of the ID area 268 and the MO area 270, and the tracks included in the zone have the same number of sectors divided by the ID area 268. The ID area is an aggregate of grooves or holes in units of information called pits, as shown in the enlarged view of the three tracks taken out on the right side, and has a sector mark, track number, sector number, CRC, etc. written therein. ing.

  Therefore, by reproducing the signal of the ID section 268, the zone number, track number, sector number, and the like where the beam is located can be detected. An MO unit 270 provided following the ID unit 268 is an area for recording and reproducing data.

  FIG. 19 shows a beam locus 274 for one rotation of the medium when the beam spot 272 is fixed at an arbitrary track position with the carriage and the lens actuator stopped. Here, for simplicity of explanation, the movement of the beam spot 272 is relatively represented as a beam path 274 while the eccentric medium surface side is actually fixed.

  As shown in FIG. 18, in the MO cartridge medium 70, since the eccentricity close to several tens of microns exists between the mechanical rotation center 264 and the track center 264, the medium was rotated with the beam spot 272 fixed. The beam locus 274 at the time causes a change in the position where one cycle corresponds to one rotation due to the amplitude twice as large as the offset.

  In order to measure the amount of eccentricity in such an optical disk medium, in the eccentricity measuring unit 260 in FIG. 7, only the focus servo is turned on with the VCM 64 and the lens actuator 60 stopped, as shown in FIG. The number of zero crosses is formed for one rotation of the tracking error signal. At this time, as shown in FIG. 20B, a rotation detection signal E4 that changes the index on the optical disk medium as a reference position, that is, a start position 275 of one rotation is used.

That is, the zero crossing of the tracking error signal E2 is counted from the state where the rotation detection signal E4 rises at the time t1 and the start position of one rotation is recognized, and the number of zero crossings until the rotation detection signal E4 rises again at the time t6. As described above, if the number N of zero crosses over one rotation period Trot can be counted, the eccentric amplitude Eamp is calculated assuming that the track pitch is TP.
Eamp = (N / 2) TP
Can be calculated as

  On the other hand, as shown in FIG. 19, the phase of the amount of eccentricity having a profile as a sine wave of one cycle in one rotation with respect to the one rotation start position 275 of the rotation detection signal E1 is based on the tracking error signal E2. The maximum time Tmax of the zero-crossing interval is obtained, and the time Tφ to the midpoint is defined as the eccentric phase. That is, in FIG. 10A, since the zero-crossing time interval from the time t3 to the time t5 is the maximum time Tmax, the time Tφ from the intermediate time t4 to the rotation start position 275 of the rotation detection signal E4 is determined. The eccentricity having a sine wave profile is determined to be the phase amount up to the zero position where the eccentricity becomes zero.

  If the eccentric amplitude Eamp and the phase Tφ can be measured based on the zero crossing of the tracking error signal E2 as shown in FIG. 20, the measurement results are set in the eccentric memory control unit 262 of the DSP 15 in FIG. Then, a sine value corresponding to each rotational position is read from the eccentric memory 200, and the sine value is obtained by multiplying the sine value by the eccentric amplitude Eamp. Measure the number of zero crosses per hit.

  FIG. 21 shows an offset current I3 for eccentricity correction, in which the tracking error signal E2 at the time of eccentricity correction is applied to the rotation detection signal E4 and the VCM 64 when the phase Tφ obtained by the measurement of FIG. It is shown together. If the eccentricity phase Tφ thus measured is correct, the eccentricity of the beam with respect to the track is corrected by flowing an eccentricity correction current I3 through the VCM 64.

  At this time, the number of zero crosses of the tracking error signal E2 obtained in one rotation cycle Trot is greatly reduced, for example, six in this case, and the number of zero crosses is the remaining eccentric amplitude after eccentricity correction. It can be confirmed that correction based on an appropriate eccentricity measurement result is performed.

  On the other hand, if the phase Tφ measured in FIG. 20 is shifted by 180 degrees from the actual phase, even if eccentricity correction is performed based on the measurement result, the amount of eccentricity will increase. In such a case, as shown in FIG. 22A, the number of zero crossings of the tracking error signal E2 obtained in one rotation cycle Trot of the rotation detection signal E4 extremely increases.

  When the number of zero crossings increases with respect to the measured value in this manner, the measured phase Tφ is shifted by 180 degrees, and thus the phase obtained by adding (Trot / 2) half of one rotation time Trot to the measured phase Tφ. Correct to (Tφ + Trot / 2). If the phase can be corrected to the correct phase in this manner, the eccentricity correction using the corrected phase can achieve an optimal eccentricity correction state in which the number of zero crossings in one rotation cycle Trot is significantly reduced as compared to the first measurement as shown in FIG. it can.

  FIG. 23 is a generic flowchart of the eccentricity measuring process by the eccentricity measuring unit 260 provided in the MPU 10 of FIG. In the optical disk device of the present invention, during the initialization processing in which the MO cartridge or CD is loaded, the second measurement processing is performed in step S2 following the first measurement processing shown in step S1.

  As shown in FIG. 20, the contents of the respective measurement processes in steps S1 and S2 are as follows: the eccentricity amplitude Eamp and the phase Tφ are measured from the zero cross of the tracking error signal, and the eccentricity is corrected using the measurement result. If the number of zero crosses increases, the phase is corrected to the opposite phase. Further, the number of zero crosses per rotation when eccentricity correction is performed for each measurement process is held.

  When the second measurement process is completed in step S2, the process proceeds to step S3, in which the difference between the number of zero crossings per rotation for the first and second times, that is, the eccentricity correction based on the measurement results in the previous and current measurement processes, is determined. Find the absolute value. If the absolute value of the difference is within a predetermined threshold value TH, for example, within the range of an allowable eccentricity correction amount, specifically, TH = 10 or less, the measurement result is determined to be correct. For example, the correction is made between the first and second times. The measurement result with the smaller number of later zero crosses is used for eccentricity correction.

  On the other hand, when the absolute value of the difference between the previous time and the current time exceeds the predetermined threshold value TH, the process returns to step S2 again, and the measurement process is performed again. In this case, the third measurement processing is performed. Then, in step S3, it is checked whether or not the absolute value of the difference between the previous time and the present time, that is, the second time and the third time is equal to or less than the threshold value TH.

  In this case, if an abnormal eccentricity measurement due to vibration or the like is performed in the first measurement processing, the absolute value of the difference between the previous time and the current time at the time of the third measurement falls within the threshold value TH and is correct. The measurement results can be used for eccentricity correction. Therefore, even if an erroneous measurement process is performed due to vibration or noise at the stage of the eccentricity measurement in the initialization process after loading the optical disk medium, even if the absolute value of the difference between the previous time and the current time falls within a predetermined threshold value. By repeating the measurement process, the use of the measurement result of the erroneous eccentricity can be automatically excluded.

  FIG. 24 is a flowchart of the eccentricity measurement processing performed in each of step S1 and step S2 in FIG. First, in step S1, one rotation detection at which the rotation detection signal rises, that is, the presence or absence of a rotation start position is detected. When one rotation is detected, the process proceeds to step S2, where a zero cross of the tracking error signal is detected. If the zero cross is obtained, the counter CNT is incremented by one in step S3.

  Subsequently, in step S4, it is checked whether or not the zero-crossing time interval is greater than the maximum value MAX. If it is larger than the maximum value MAX, the newly obtained TZC time interval is set to the maximum value MAX in step S5. Then, for the TZC time interval with the maximum value MAX, the time from the detection of one rotation is entered in the phase Tφ in step S6. The above process is repeated until the next one rotation is detected in step S7.

  If the phase Tφ is obtained from the counter CNT for one rotation and the maximum value of the TZC time interval in the counter CNT by one rotation detection in step S7, the eccentric amplitude Eamp is calculated in step S8. Then, the eccentric phase Tφ is obtained in step S9. Subsequently, in step S10, an eccentricity correction operation is performed based on the measured amplitude Eamp and phase Tφ. Then, in step S11, the counter CNT measures the number of zero crossings due to the eccentric amount of one rotation while performing the eccentricity correcting operation.

  In step S12, the value of the counter CNT before and after the measurement, that is, the value of the zero cross, is compared. If the value after the correction is reduced, the process is terminated as a correct measurement result. If it has increased after the correction, the eccentricity phase Tφ is corrected to * Tφ shifted by 180 degrees in step S13, and the eccentricity correction operation is performed.

  FIG. 25 is a flowchart of the eccentricity correction operation based on the measured amplitude Eamp and the phase Tφ in step S10 in FIG. This eccentricity correction control operates every interruption of a predetermined sampling clock. When there is a sampling interruption, the measured eccentric phase Tφ is subtracted from the time tx from the rotation detection in step S1. If the calculated value t is smaller than 0 and is a negative value, the process proceeds to step S3 to correct the value by adding one rotation time Trot.

  The reason is as shown in the time chart of FIG. FIG. 26A shows a sampling clock, and FIG. 26B shows a rotation detection signal E4. Assuming that the eccentricity correction control in FIG. 25 is performed at the timing of the sampling clock at the next time t1 following the rise of the rotation detection signal E4, the time t calculated in step S1 at this time is t = t1−Tφ, Take a value.

  Therefore, the process proceeds from step S2 to step S3 to correct the rotation detection signal E4 by adding one rotation cycle Trt. As a result, the correction value is (t1 + Trot). On the other hand, the address of the eccentric memory 200 stores the value of sin2πft with the position having a delay of the phase Tφ as the zero point relative to the rotation start position at which the rotation detection signal E4 rises. Therefore, (t = t1 + Trot) calculated in step S3 is the value of the point 282 in the eccentric memory 200.

  Assuming that the eccentric memory 200 also exists on the phase Tφ side, the value of this point 282 is the same sine value as the value of the rotational position corresponding to the time t1 that becomes the point 282. Therefore, until the elapsed time tx from the rotation start position exceeds the phase Tφ, the eccentric memory 200 is read by the correction in step S3.

  In step S4, since sin2πf is read from the eccentric memory 200 using the time t obtained in step S3 or step S1 as an address, the amount of eccentricity is corrected by multiplying the sin2πf by the measured eccentric amplitude Eamp. The eccentricity can be corrected by obtaining the correction current Ie to be added and adding the correction current Ie to the drive current for the VCM 64.

  Here, the eccentric memory 200 in FIG. 17 stores sine data sinθ for every 32 samples by a sample clock that determines the operation timing of the DSP 15. Therefore, the number of sine data for one rotation stored in the eccentric memory 200 is 36 when the rotation speed of the MO cartridge medium is 3600 rpm, and the sine data for every 10 degrees is stored in the table. Data between sine data registered in the eccentricity memory 200 is obtained and output by an approximate calculation by linear interpolation.

  When a CD is loaded, the optical disk drive changes the number of rotations of the medium to 2400 rpm corresponding to the CD. When the medium rotational speed changes in this manner, the number of data stored in the eccentric memory 200 changes because the read cycle of the eccentric memory 200 is constant at 32 samples. In the case of 2400 rpm, the number of data of sine values required for eccentricity correction of one rotation is 54, and sine data of about 6.7 degrees is required. Therefore, when the change in the rotation speed is recognized from the loaded medium, the eccentric memory 200 is updated so that the sine data suitable for the changed rotation speed is stored.

5. Envelope servo FIG. 27 is a circuit block diagram of the TES detection circuit 50 provided in the controller 10 of the optical disk drive in FIG. The TES detection circuit 50 receives light receiving signals E5 and E6 from the light receiving units 46-1 and 46-2 of the two-segment detector 46 provided on the optical unit side. The TES detection circuit 50 includes peak hold circuits 290 and 292, a subtractor 294, and an envelope detection switching circuit 295. The peak hold circuits 290 and 292 have a circuit configuration represented by the peak hold circuit 290 of FIG.

  In the peak hold circuit 290 of FIG. 28, a capacitor C1 for peak hold is connected via a resistor R1 and a diode D following an input terminal. A discharge resistor R2 is connected in parallel with the capacitor C1, and a discharge resistor R3 is connected via an analog switch 296. The analog switch 296 is on / off controlled by a switching signal E9 from the envelope detection switching circuit 295 in FIG.

  When the envelope servo is turned on, that is, when the envelope detection is performed, the analog switch 296 is turned off as shown in the figure. At this time, the discharge time constant of the capacitor C1 is determined by the resistor R2, and the discharge time constant determined by the values of C1 and R2 is set to the envelope detection for suppressing the drop of the tracking error signal due to the return light of the ID portion of the 540 MB or 640 MB MO cartridge medium. Set a time constant that can be used.

  To turn off envelope detection, the analog switch 296 is turned on. When the analog switch 296 is turned on, a discharge resistor R3 is further connected in parallel to the capacitor C1 in addition to the discharge resistor R2. Therefore, the discharge resistance is reduced to the parallel resistance value of the resistances R2 and R3, whereby the envelope detection is substantially turned off. Of course, when it is desired to completely turn off the envelope detection, the capacitor C1 itself may be separated by the analog switch 296.

In the envelope detection switching circuit 295 of FIG. 27, the envelope detection of the peak hold circuits 290 and 292 is on / off controlled by the switching control signal from the DSP 15 of FIG. The ON / OFF of the envelope detection is as follows.
(A) When loading a 128 MB MO cartridge medium having a mirror section, the envelope detection is turned off.
(B) In a loading state of the 230 MB MO cartridge medium, when an access command for setting a target track to a non-user area having a mirror section outside the user area, that is, a process area, the envelope detection is turned off.
(C) In the seek control of the 540 MB and 640 MB MO cartridge media, the envelope detection is turned off when a high-speed seek exceeding a predetermined value is detected. Turning off the envelope detection during the high-speed seek is performed in the same manner for the user area of the 230 MB MO cartridge.

  The predetermined speed for judging the high-speed seek is shorter than the time from the peak level of the tracking error signal to the 0 level according to the discharge time constant when the envelope detection determined by the capacitor C1 and the resistor R2 in FIG. 28 is turned on. High-speed seek at track zero-cross intervals may be performed.

  FIG. 29 is an explanatory view of a medium surface having a mirror portion. In the ID portion 268 and the MO portion 270, a group 298 is formed for each track, and for the ID portion 268, an embossed pit is formed in an area sandwiched by the group 298. Although a mirror 302 is formed, a mirror part 300 having a flat mirror surface exists between the two.

  FIG. 30 shows the effect of the beam return light from the ID section on the tracking error signal in such a medium track. FIG. 30A shows the light receiving signal E5 of the two-segment detector 46, and FIG. 30B shows the light receiving signal E6 of the two-segment detector 46, each of which falls into the amplitude of the light receiving signal corresponding to the unevenness of the pit 302 of the ID section 268. Cause

  FIG. 30C shows a tracking error signal E2 obtained by subtracting the received light signal E6 from the received light signal E5. A drop obtained by adding the drop of the ID portion in the received light signal occurs in the amplitude component. If the amplitude drop 308 occurs in, for example, a low amplitude portion of the tracking error signal E2, a track zero cross occurs, and a track count is incorrect.

  Thus, by turning on the envelope detection by the peak hold circuits 290 and 292 in FIG. 27, the fluctuation caused by the return light from the ID section can be suppressed to a smooth fluctuation amplitude 309 by the envelope detection as shown in FIG. .

  FIG. 31 shows the light receiving signals E5 and E6 and the tracking error signal E2 due to the return light from the mirror unit 300 in FIG. 29, in a state where the envelope detection is turned off. Since the return light from the mirror unit 300 is a signal of the same level and the same polarity for both of the light receiving signals E5 and E6, the tracking error signal E2 corresponds to the mirror unit like a dip 314 due to the difference between the two. Causes signal loss.

  FIG. 32 is a signal profile in the case where the envelope detection is further turned on for the detection of the tracking error signal of the medium having the mirror section of FIG. When the envelope detection is turned on, the dips 304 and 306 corresponding to the ID portions of the light-receiving signals E5 and E6 are suppressed as amplitude dips 316 and 318, and the amplitude dip 308 in the tracking error signal E2 is also expressed as amplitude 310. Be suppressed.

  However, as for the reflected components 310 and 312 from the mirror portion following the ID portion, since the envelope detection is turned on after the reflected components rise, the discharge time constants for the envelope detection as shown by the waveforms 320 and 322 are present. As a result, as shown by the tracking error signal E2, the signal amplitude 324 of the tracking error signal following the mirror section is greatly distorted.

  In order to avoid the distortion of the tracking error signal E2 shown in FIG. 32 due to the return light of the mirror portion when the envelope detection is turned on, the envelope detection is turned off and the tracking error signal E2 shown in FIG. 31 is used. It is desirable to do.

  FIG. 33 shows a falling waveform 330 when the envelope detection is on and a falling waveform 332 when the envelope detection is off when the rectangular wave pulse 326 is input to the peak hold circuit 290 of FIG. If the envelope detection is on, the falling waveform 330 after the peak detection falls with a gradual time constant as shown in the output of FIG. 33 (B), so that smooth tracking by the envelope detection suppressing the drop of the ID section and the like is performed. An error signal can be created. On the other hand, for a medium having a mirror section, the envelope detection is turned off to cause a rapid falling 332 of the waveform as shown in FIG. 33C, whereby the light receiving component due to the return light of the mirror section gradually falls. This can prevent the tracking error signal from being greatly distorted.

  FIG. 34 shows the tracking error signal at the time of high-speed seek for ON and OFF of the envelope detection. FIG. 34A shows a tracking error signal at the time of high-speed seek when the envelope detection is turned off, and the upper and lower peak amplitudes of the tracking error signal and the zero cross therebetween are accurately reproduced. On the other hand, when the envelope detection is turned on, a gently falling waveform 330 as shown in FIG. 33B is obtained, so that the zero-cross interval is shortened. At the time of high-speed seek, the amplitude components of the upper and lower peaks as shown in FIG. , And no longer functions as a tracking error signal.

  In the present invention, during high-speed seek, in order to avoid loss of the tracking error signal as shown in FIG. 34 (B), envelope detection is turned off, and even when high-speed seek is performed as shown in FIG. 34 (A). A tracking error signal can be created accurately.

  FIG. 35 is a flowchart of the envelope serve control process of FIG. First, if there is a medium loading in step S1, the type of the loaded medium is recognized. If it is recognized in step S2 that the loaded medium is a 128 MB MO cartridge medium, the flow advances to step S3 to turn off the envelope servo.

  If it is recognized in step S4 that the loaded medium is a 230 MB MO cartridge medium, it is checked in step S5 whether or not the access is to the non-user area. If it has been received, the process proceeds to step S6 to turn off the envelope servo. If the access is not for the non-user area, the envelope servo is turned on in step S7.

  FIG. 36 shows the ON / OFF control of the envelope servo during the seek control performed in the ON state of the envelope servo. During the seek control, in step S1, it is checked whether the seek speed obtained from the zero-crossing time interval of the tracking error signal is equal to or higher than a predetermined threshold speed Vth. If the seek speed is equal to or higher than the threshold speed Vth, it is determined that the seek is a high-speed seek, and the envelope servo is turned off in step S2.

  If the seek speed is less than the threshold value Vth, the envelope servo is kept on in step S3. The above processing is repeated until the end of the seek is determined in step S4. Of course, if the seek speed becomes Vth or less during the seek, the envelope servo is turned on at step S3 at that point.

6. Focus Servo FIG. 37 is a functional block diagram of a PID calculation unit 96 provided for focus servo for the focus actuator 56 realized by the DSP 15 of FIG. The PID operation unit 96 includes a differentiation operation unit including a differentiator 340 and a gain multiplier 342, an integration operation unit including an integrator 344 and a gain multiplier 346, and a proportional operation unit using a gain multiplier 348.

  To each of the differentiator 340, the integrator 344, and the gain multiplier 348, the focus error signal E1 generated based on the received light output of the return light of the medium by the FES detection circuit 48 of FIG. 2 is input. The outputs of the gain multipliers 342, 346, and 348 are multiplied by an adder 350, and a current is finally supplied to the focus actuator 56 by the DA converter 108 via the servo switch 98 as a focus servo signal by PID calculation, and the focus Response focusing is performed so that the error signal E1 becomes 0.

  In the present invention, a gain control section 352 is newly provided for the PID calculation section 96 of such a focus servo. The ID gate signal E11 is input to the gain control unit 352 from the formatter 18 shown in FIG. When the ID gate signal E11 from the formatter 18 is enabled, the gain control unit 352 switches the gain of the gain multiplier 342 provided following the differentiator 340 to zero. As a result, while the gate signal E11 is enabled, the differential component output from the gain multiplier 342 becomes 0, and the PID operation unit 96 operates as a PID operation unit.

  FIG. 38 shows an operation when the gain of the gain multiplier 342 of the differentiator 340 is not set to 0 in synchronization with the ID gate signal E11 by the gain control unit 352. The focus error signal E1 fluctuates as shown in FIG. 38B, corresponding to the ID portion of the track in FIG. At this time, if the PID calculation function of the PID calculation unit 96 in FIG. 37 is enabled, the focus error signal E1 is synchronized with the fall and rise before and after the ID portion, and the focus error signal E1 mainly depends on the differential component. The current I1 is supplied in a pulse form.

  That is, when moving from the MO section to the ID section, autofocus for focusing the objective lens on the ID section is applied, and when exiting from the ID section to the MO section, reverse autofocus for focusing the objective lens on the MO section is applied, This is repeated for each ID section on the track. As a result, as shown in FIG. 38 (D), the lens position of the objective lens is alternately controlled to the focus position corresponding to the MO section and the ID. However, since the ID section is in a recording state using physical pits, precise autofocus control for magneto-optical recording such as the MO section is unnecessary, and it is not necessary to focus on the ID section. The ID signal can be reproduced with sufficient S / N from the return light of the ID section.

  Therefore, in the present invention, as shown in FIG. 39 (D), in synchronization with the ID gate signal E11 obtained from the formatter in synchronization with the track ID section, as shown in FIG. The differential gain Gd of the gain multiplier 342 for multiplying the gain of the differentiator 340 is switched to zero. In the ID section, the PID calculation section 96 operates as a PI calculation section, and even if a step-like change occurs in the focus error signal E1 corresponding to the ID section as shown in FIG. It does not appear at the output of unit 96.

  As a result, the current I1 to the focus actuator 56 does not change in the ID section as shown in FIG. Needless to say, the position of the objective lens in FIG. 38F does not change for each ID part, and the focused state with respect to the MO part can be stably maintained. Here, in the embodiment of FIG. 37, the gain control unit 352 switches the gain of the gain multiplier 342 of the differentiator 340 to 0 in synchronization with the ID gate signal E11. The gain of the configured gain multiplier 348 may be set to 0 in synchronization with the ID gate signal E11.

  For this reason, the PID operation section 96 performs only the integration operation at the timing of the ID section, so that unnecessary operation of the focus servo due to the focus error signal E1 that changes in the ID section can be suppressed more reliably. As a matter of course, a gentle fluctuation in the vertical direction due to the bending of the disk medium can be maintained with a sufficiently long time constant by the integral proportional control or the integral control to maintain a stable autofocus state.

  In the above-described embodiment, an optical disk drive that can be used by loading both the MO cartridge medium and the CD medium is taken as an example. Requires a common optical system for detecting a tracking error signal. Usually, the push-pull method is adopted for the MO cartridge medium, while the three-beam method is usually used for the CD medium. However, since the optical system of the MO cartridge medium and the CD medium cannot be shared by using the three-beam method, the CD medium is also one beam in the present invention. The push-pull method cannot be used due to the pit depth.

  Therefore, the present invention employs a heterodyne method for tracking error detection of a CD medium. Thus, the positioner can be controlled by detecting the tracking error signal by the same optical unit regardless of whether the medium is an MO cartridge medium or a CD medium.

Further, the present invention is not limited to an optical disk drive capable of using both the MO cartridge medium and the CD medium, but may be realized as any usable optical disk drive of, for example, 128 MB, 230 MB, 540 MB or 640 MB per MO cartridge medium. .

Diagram for explaining the principle of the present invention 1 is a block diagram of an optical disk drive according to the present invention. Schematic explanatory view of the device structure of the present invention using an MO cartridge Schematic explanatory view of the device structure of the present invention using a CD Functional block diagram of the servo system realized by the DSP of FIG. FIG. 5 is an explanatory diagram of ON / OFF of the servo control mode of the analog switch of FIG. Explanatory drawing of the servo control mode of FIG. Explanatory drawing of one track seek according to the present invention. Flowchart of one-track seek control according to the present invention Explanatory drawing of fine seek control according to the present invention using an MO cartridge that simultaneously drives a lens actuator and a VCM Detailed explanatory diagram of the deceleration control drawn into the target track in FIG. Flowchart of fine seek control according to the present invention Flowchart of fine seek control according to the present invention (continued) Detailed flowchart of the deceleration control in FIG. Detailed flowchart of deceleration control in FIG. 12 (continued) Explanatory diagram of deceleration control to pull in to a target track when using a CD Functional block diagram of eccentric memory control of the present invention Illustration of eccentricity in MO media Explanatory diagram of a beam trajectory crossing a track according to media eccentricity Time chart of tracking error signal, rotation detection signal and VCM current during eccentricity measurement Time chart of tracking error signal, rotation detection signal and VCM current at the time of eccentricity correction using eccentricity measurement result Time chart of tracking error signal, rotation detection signal, and VCM current at the time of eccentricity correction when the rotation phase is reversed Generic flowchart of measurement processing by the eccentricity measurement unit in FIG. Flow chart of details of the eccentricity measurement processing in FIG. Flowchart of eccentricity correction control based on eccentricity measurement results Explanatory drawing of the correction value output process by reading the eccentric memory synchronized with the sample clock FIG. 2 is a block diagram of the TES detection circuit of FIG. 2 used for envelope servo. Circuit diagram of the peak hold circuit of FIG. Illustration of media mirror Signal waveform diagram of the received light signal and TES signal when the envelope servo is turned off, and the TES signal when the envelope servo is turned on Signal waveform diagram of light receiving signal and TES signal by mirror unit in FIG. 29 when envelope servo is off Signal waveform diagram of light receiving signal and TES signal by mirror unit in FIG. 29 when envelope servo is on FIG. 28 is an explanatory diagram of an output waveform when the envelope servo of the peak hold circuit of FIG. 28 is turned on and off for a rectangular input. Explanatory drawing of the TES signal at the time of high-speed seek for ON / OFF of the envelope servo Flowchart of ON / OFF control of envelope servo according to the present invention when loading a medium Flowchart of ON / OFF control of envelope servo according to the present invention during seek FIG. 5 is a functional block diagram of the focus PID calculation unit of FIG. 5 for preventing a malfunction in the ID unit. FIG. 37 is a time chart of the focus control in the ID section when the respective controls of the differentiation, integration, and proportional are enabled. 37 is a timing chart of the focus control in the ID section when the differential control of FIG. 37 is turned off and the control of integration and proportionality is enabled.

Explanation of reference numerals

10: Controller 12: Enclosure 14: MPU
15: DSP
16: Interface controller 18: Formatter 20: Buffer memory 22: Encoder 24: Laser diode control circuit 26: Decoder 28: Read LSI circuit 30: Laser diode 32: Detector 34: Head amplifier 36: Temperature sensors 38, 42, 54, 58 , 62: driver 40: spindle motor 44: electromagnet 46: two-part detector 48: FES detection circuit 50: TES detection circuit 52: lens position sensor 56: focus actuator 60: lens actuator 64: VCM (carriage actuator)
66: Housing 68: Inlet door 70: MO cartridge 72: MO medium 76: Carriage 78: Fixed optical system 80: Objective lens 82: CD medium 84: Tray 86: Turntable 88, 124, 144: A / D converter 94, 100, 130, 158, 150, 174, 180, 190: phase compensators 96, 140, 152, 176, 184: PID calculators 98, 118, 142, 156, 178, 186: servo switches 108, 166, 206: D / A converter 200: eccentric memory 210: acceleration period 212: pre-deceleration period 214: deceleration period 250: eccentricity measurement unit 254: eccentricity memory control unit 280, 282: peak hold circuit 284: subtractor 285: discharge time constant switching circuit 296: Analog switch 300: Mirror unit

Claims (7)

An objective lens for irradiating the medium with a light beam,
A positioner for moving the objective lens in a direction transverse to a track of the medium,
By the drive control of the positioner, an access control unit that moves the light beam from the optical unit to the target track and on-track,
A tracking error signal generation circuit for generating a tracking error signal corresponding to a position in a direction crossing the track of the light beam based on a light receiving output of the medium return light obtained by the optical unit; In
An eccentricity measuring unit that measures, as eccentricity information, an eccentricity amplitude and an eccentricity phase with respect to a start position of one rotation based on detection of a zero cross of the tracking error signal while the driving of the carriage and the lens is stopped;
An eccentric memory storing a sine value for one rotation corresponding to the rotational position of the medium;
An eccentricity correction unit that determines the medium eccentricity from the sine value read from the memory and the eccentricity measurement information by the measurement unit, and controls the positioner to cancel the eccentricity,
An optical storage device comprising:
2. The optical storage device according to claim 1, wherein the eccentricity correction unit tracks the eccentricity to half the number of zero crosses of the tracking error signal for one rotation of the medium obtained in synchronization with a medium detection signal indicating one rotation of the medium. The eccentricity amplitude Eamp is obtained by multiplying a pitch by a pitch, and the time from the start position of one rotation of the rotation detection signal to the middle point of the maximum zero-cross interval time of the tracking error signal is obtained as the eccentric phase Tφ. Storage.
In the optical storage device according to claim 1, the eccentricity correction unit includes:
When the difference (tx−Tφ) between the elapsed time tx of the current rotation position with respect to the start position of one rotation and the eccentric phase Tφ is negative, the sine obtained by adding the one rotation time Trot to the difference (tx−Tφ + Trot). Reading out the value sin2πf (tx−Tφ + Trot) from the eccentricity memory and correcting it;
When the difference (tx−Tφ) is zero or positive, a sine value sin2πf (tx−Tφ) obtained from the difference is read out from the eccentric memory and corrected.
2. The optical storage device according to claim 1, wherein the eccentricity measurement unit measures the number of zero crossings per rotation in an eccentricity correction state by the eccentricity correction unit based on the measured eccentricity information. An optical storage device, wherein when the number exceeds the number of zero crossings at the time of measurement, the eccentric phase Tφ obtained in the measurement processing is corrected to the opposite phase.
5. The optical storage device according to claim 4, wherein the eccentricity measuring unit corrects the eccentricity to an eccentricity opposite phase (Tφ + Trot / 2) obtained by adding a half of one rotation time Trot to the measurement phase Tφ as an opposite phase. An optical storage device characterized by the following.
2. The optical storage device according to claim 1, wherein the eccentricity measurement unit performs measurement of the eccentricity information and eccentricity correction after the measurement twice, and compares the number of zero crossings in one rotation after each eccentricity correction. When the difference exceeds a predetermined threshold, the measurement and correction of the eccentricity are repeated until the difference becomes equal to or smaller than the threshold.
  2. The optical storage device according to claim 1, wherein the eccentricity memory stores a sine value for one rotation of a number determined by a fixed read cycle and a medium rotation speed, and the eccentricity memory is used when the medium rotation speed changes. An optical storage device for updating a sine value for one rotation of a number determined by the medium rotation speed after the change.

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