JP2785217B2 - Optical disk drive - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device in which an optical head scans a recording surface portion of an optical disk on which recording tracks in a circular pattern are formed with a light beam.

B SUMMARY OF THE INVENTION The present invention relates to an optical disc apparatus in which a recording surface portion of an optical disc on which recording tracks in a circular pattern are formed is scanned by an optical head with a light beam. Is recorded in advance on each recording track, and traverse information for the optical disc is detected from the recording track based on a reproduction output by an optical head that scans a recording surface portion of the optical disc with a light beam, and is obtained at predetermined intervals. Detecting the amount of change in the traverse information to form higher-order bit data of the access speed, and forming tracking error information proportional to a displacement of a light spot by the light beam in a track pitch direction with respect to a recording track on the optical disk; The above traverse is added to the tracking error information. Subjected to Myuteingu treated with change position near the distribution,
By detecting the amount of change in the tracking error information subjected to the muting process and forming the lower bit data of the access speed, the optical head by the optical head can be used to convert the traverse information and the tracking error information subjected to the muting process. The access control can be performed accurately.

C. Prior Art In recent years, optical disks using an optical or magneto-optical signal recording / reproducing method have been developed and are being supplied to the market. These optical disks include so-called CDs
(Read only memory) type such as (compact disk), so-called write-once type in which the user can write data once, and data storage such as magneto-optical disk A rewritable (so-called overwrite) rewritable recording medium and the like are known.

In an optical disk apparatus using an optical disk using an optical or magneto-optical signal recording / reproducing method as a recording medium, a laser beam for recording / reproducing information while rotating the optical disk at a constant angular velocity or a constant linear velocity by a spindle servo. Focus servo or tracking servo is applied to an optical head that incorporates a laser diode that outputs laser light or a photodiode that detects reflected light of the laser light from the optical disk, and scans a recording track of the optical disk with the laser light to transfer information. I am going to do recording and playback.

Further, in the above optical disk device, in order to move the optical head to a recording track position for recording and reproducing information by scanning with a laser beam, for example, as shown in FIG. the distance between P _a as x, x is to control the moving velocity v of the optical head so that the reference speed v _R at that time. Conventionally,
The moving speed v of the optical head is detected by, for example, a speed sensor fixed to a mechanical base.

Further, as one of the technologies for realizing a unified recording format for the above-mentioned various optical disks, a so-called sector disk in a hard disk in the magnetic disk field is used.
Similarly to the servo, servo signals such as clock pits and tracking pits are recorded on concentric or spiral tracks on the disk at predetermined intervals or at predetermined angles in advance (so-called preformatting). A so-called sampled servo technique has been proposed in which continuous servo control is performed by sampling and holding these discrete servo signals. As this type of optical disk, for example, an optical disk (50) having a recording format as shown in FIG. 11 has been conventionally known.

In the optical disc (50) shown in FIG. 11, an annular label portion (52) is arranged around the central hole (51), and further, an annular recording surface portion (53) extending around the label portion (52). ) Is provided. Then, the recording surface portion (5
3) is provided with spiral recording tracks (tk) forming a large number of orbital patterns surrounding the central hole (51), and each of them has a predetermined number m (eg, m) = 32) sectors (sc ₁ ), (sc ₂ ) to (sc
_m ), and a plurality of sectors having a corresponding relationship between the orbital tracks, such as a sector (sc ₁ ) in each orbital track, are arranged in the radial direction of the optical disc (50). It has become something. The optical disk (50) provided with such a recording track (tk) is mounted on an optical disk device and rotated in the direction of an arrow (r) to record or reproduce information using a light beam. Provided.

Each sector (sc ₁ ), (s
Each of c ₂ ) to (sc _m ) has an address information section (ad) arranged at the start end thereof, and is arranged along the recording track (tk) following the address information section (ad). A predetermined number n (for example, n = 43) blocks (b
l ₁ ) and (bl ₂ ) to (bl _n ). As for the blocks (bl ₁ ), (bl ₂ ) to (bl _n ), for example, as in the block (bl ₁ ) in each sector (sc ₁ ), (sc ₂ ) to (sc _m ), In the optical disk (50), a plurality of blocks having a corresponding relationship in
Are arranged in the radial direction. The block (b) in each such sector (sc ₁ ), (sc ₂ ) to (sc _m )
In each of l ₁ ), (bl ₂ ) to (bl _n ), a control recording area (ar _C ) is provided at the start end thereof, and an information writing area (ar _D ) following the control recording area is provided, and unit recording It constitutes a division. The control recording area (ar _C ) of each of the blocks (bl ₁ ), (bl ₂ ) to (bl _n )
Include tracking information pits (q _a ) and (q _b ) shifted outward and inward with the track center line (k _c ) therebetween, and a clock positioned on the track center line (k _c ). The information pits (q _c ) are formed in advance at predetermined mutual intervals along the track center line (k _c ). In addition, the tracking information pits (q _a ),
(Q _b ) and a direction perpendicular to the track center line (k _c ) of the clock information pit (q _c ), that is, the optical disc (5
Referring to the radial direction of arrangement of 0), as shown in FIG. 12, although the tracking information pits (q _b) and clock information pit (q _c) are linearly arranged in each radial direction On the other hand, the tracking information pits (q _a ) are arranged such that their positions are shifted in the longitudinal direction of the track (tk), for example, every 16 tracks. Thus, the tracking information pits _{(q a), (q b} ) and clock information pits (q _c) the control record region (a
r _C) to provided an optical disc (50) is mounted in the optical disk apparatus Upon being subjected to the information recording or information reproducing by an optical beam, the tracking information pits of the control record region (ar _C) (q _a), (Q _b ) and the clock information pit (q _c ) are read by a light beam and used for various servos and clock generation. That is, a clock is reproduced from the reproduction output of the clock information pit (q _c ) to form a necessary timing clock, and the tracking information pit (( _{c c} )) is shifted outward and inward with respect to the track center line (k _c ). q _a), performs focus control based or perform tracking control to seek the tracking error, the reproduction output of the mirror region on the basis of the reproduction output for (q _b). Further, the reproduction output of the tracking information pit (q _a ) uses a so-called traverse count for obtaining the track number currently being scanned by the optical pickup by using the array whose position is shifted every 16 tracks as described above. Used to do.

D Problems to be Solved by the Invention Incidentally, optical discs generally have eccentricity, and the target track position moves due to rotation. Therefore,
As described above, the moving speed of the optical head detected by the speed sensor provided on the mechanical base is not the true speed at which the light spot moves on the optical disk.

Therefore, recently, attempts have been made to detect the moving speed of the light spot on the optical disk.

However, when the sampled servo is adopted, the track theorem cannot be detected unless the light spot crosses one track in a time at least twice as long as the sampling period due to the sampling theorem. There is a problem that it cannot be detected.

Here, in the optical disk d shown in FIG. 11, the arrangement of the tracking information pits (q _a ) is changed as described above.
Since the position is shifted for every 16 tracks and used for the traverse count, the traverse count can be performed in units of 16 tracks. Speed detection can be performed. However, when performing speed detection during low-speed movement, the phase is delayed due to the dead time and the hold time, so that there is a problem that high-accuracy speed detection cannot be performed.

For example, as shown in FIG. 13, comparing the true speed v _o of the light spot at the time of deceleration with the speed v _d detected from the traverse information, it is found that the speed from the point A to the point B located 16 tracks ahead is obtained. When the time T _k-1 is measured, the average speed of the section is determined, and this value is equal to the true speed v _{o at the} point C located at a position T _k−1 / 2 ahead of the point A. This value is
The point D determined at the point B after the elapse of the dead time T _{U (k−1)} (T _{U (k−1)} = T _k−1 / 2) from the point C and located at a position advanced by the next 16 tracks Held until In the D point, the error of the delta _k is generated between the velocity v _d detected from true velocity v _o the traverse information. Time _{T k-1/2 + T} k from the point C to the point D is the phase delay. The time _Tk is a time at which the light spot advances by 16 tracks. Therefore, the moving speed of the light spot becomes slow, the time T _k increases, the speed detection error becomes large, after the access, the speed reaches the target track does not become zero, increased overshoot become. This is a low speed one
The same can be said for the track count and one track count of the continuous servo. However, the speed cannot be detected while one track is being advanced. Usually, the tracking error signal is non-linear as shown in FIG.

As described above, in the conventional optical disk device, when the optical head is moved to the target track position to record and reproduce information on a target recording track, the access speed cannot be detected with high accuracy. There was a problem that the target track could not be reached by a single access operation, and the access time was prolonged.

Therefore, the present invention has been made in view of the above-described conventional problems,
It is an object of the present invention to provide an optical disk device capable of moving an optical head to a target track position and quickly and reliably recording and reproducing information on a target recording track.

E Means for Solving the Problems Therefore, in order to solve the above-described problems, the present invention provides, in each recording track, traverse information indicating a recording pattern of a circular pattern formed on a recording surface portion in units of one track. An optical disc device in which the recording surface portion of a previously recorded optical disc is scanned by an optical head with a light beam, wherein traverse information detection for detecting traverse information for the optical disc from the recording track based on a reproduction output by the optical head. Means, first access speed information forming means for detecting an amount of change in traverse information obtained every predetermined period by the traverse information detecting means to form higher-order bit data of the access speed, and reproducing output by the optical head. The recording spot of the light spot by the light beam on the optical disc is Tracking error information forming means for forming tracking error information proportional to the displacement of the traverse information with respect to the traverse information detected by the traverse information detecting means. And a second access speed information forming means for detecting a change amount of the tracking error information subjected to the muting process by the muting device and forming lower-order bit data of the access speed. The optical head performs access control of the optical disk based on the traverse information and the tracking error information subjected to the muting process.

F Function In the optical disc apparatus according to the present invention, traverse information indicating a track in units of one track is traversed based on a reproduction output by an optical head that scans a recording surface portion of an optical disc previously recorded on each recording track with a light beam. The information detecting means detects traverse information for the optical disk from the recording track, and the tracking error information forming means calculates the tracking error information proportional to the displacement of the light spot by the light beam in the track pitch direction with respect to the recording track on the optical disk. To form The traverse information gives position information on a track-by-track basis.
The tracking error information gives position information within one track.

Since the traverse information and the tracking error information are formed by different means, the position information indicated by combining them has discontinuity due to an offset or the like.

Muting means performs muting processing on the tracking error information obtained by the tracking error information forming means in the vicinity of a change position of the traverse information detected by the traverse information detecting means,
Eliminate the discontinuity.

Then, the first access speed information forming means detects the amount of change in the traverse information obtained every predetermined period by the traverse information detecting means, and forms the upper bit data of the access speed. Further, the second access speed information forming means detects the amount of change of the tracking error information subjected to the muting process by the muting means, and forms the lower bit data of the access speed. Tracking error information detected from a reproduction output by an optical head that scans the recording surface portion of the optical disc with a light beam,
Although the velocity information is not obtained even when differentiated because it is nonlinear, the tracking error information forming means forms the tracking error information proportional to the displacement from the recording track in the track pitch direction of the recording track. Even when the light spot crosses one track at a speed at which the frequency of the tracking error information is equal to or more than 1/2 of the sampling frequency, the position of the light spot between the tracks can be known from the tracking error information.

G Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

The block diagram of FIG. 1 uses, as a recording medium, an optical disk (1) having a recording format as shown in FIGS. 2 and 3 proposed by the present applicant as Japanese Patent Application No. 62-207542, for example. 1 shows a configuration of a servo system when the present invention is applied to an optical disk device.

As shown in FIG. 2, the optical disk (1) used in the optical disk device has an annular label portion (42) disposed around a central hole (41) and extends around the label portion (42). An annular recording surface (44) is provided. The recording surface portion (44) is provided with a spiral recording track (TK) for forming a large number of orbital patterns surrounding the central hole (41). It is divided into several m (for example, m = 32) sectors (SC ₁ ), (SC ₂ ) to (SC _m ), and for example, a sector (SC ₁ ) in each orbiting track,
A plurality of sectors having a corresponding relationship between the respective orbital tracks are arranged in the radial direction of the optical disc (1). Each of the sectors (SC ₁ ), (SC ₂ ) to (SC _m ) in each of the orbiting tracks is
An address information section (AD) is arranged on the start end side, and a predetermined number n (for example, n = 4) arranged along the recording track (TK) following the address information section (AD).
3) blocks (BL ₁ ), (BL ₂ ) to (BL _n ). The block _{(BL 1), (BL 2} ) ~ (B
L _n ), for example, each sector (SC ₁ ), (SC ₂ ) to
Like the block (BL ₁ ) in (SC _m ), a plurality of blocks having a corresponding relationship between the respective sectors are arranged in the radial direction of the optical disc (1). Each of such sectors (SC ₁ ), (SC ₂ ) to (SC
_{In each} of the blocks (BL ₁ ), (BL ₂ ) to (BL _n ) in _m ), a control recording area (AR _C ) is provided on the starting end side, and an information writing area (AR _D ) following the control recording area (AR _C ) is provided.
Are provided to constitute a unit recording section.

Then, the above blocks (BL ₁ ), (BL ₂ ) to (BL _n )
The control recording area (AR _C ) is divided into a servo area (AR _S ) and a traverse area (AR _T ).
R _S ), a pair of tracking information pits (Q _A ) and (Q _B ) are separated from each other by a predetermined distance (8 channel bits in this example) in the track direction with the track center line (K _c ) therebetween. together are positioned shifted 1/4 track pitch, respectively inward, clock information pits (Q _C) is the tracking information pits (Q _a), the track center line situated in the middle of the (Q _B) (K _c )
Further, in the above traverse region (AR _T) spaced apart by a distance P which a pair of traverse data pits (Q _D) and (Q _E) is allocated for each recording track as a reference the clock information pits (Q _C) distribution It is formed.

Here, each control recording area (AR _C ) is 3
It has a data recording capacity of 0 channel bits, and allocates seventh and fifteenth channel bits as recording positions of the tracking information pits (Q _A ) and (Q _B ). assign the first channel bit as the recording position of _C), further, the traverse information pits (Q _D), are assigned to 27 channel bits from the 19 channel bits as the recording area of the (Q _E). The tracking information pits (Q _A ), (Q _B ), clock information pits (Q _C ), and traverse information pits (Q _D ), (Q _E ) are orthogonal to the track center line (K _c ), The arrangement of the optical disc (1) in the radial direction will be described. As shown in FIG. 3, the tracking information pits (Q _A ) and (Q _B ) and the clock information pit (Q _C ) are respectively arranged in the radial direction. While the traverse information pits (Q _D ) and (Q _E ) are arranged linearly, one of the traverse information pits (Q _D )
Are shifted in the track direction by one channel bit in units of four tracks, and the other traverse information pit (Q _E ) is excluded except where the traverse information pit (Q _D ) changes position in units of four tracks. Thus, the position is shifted in the track direction by one channel bit for each track, and a different bit pattern is set for each track, with 16 tracks as one unit.

In the optical disc (1) in such the above recording format, the traverse information pits (Q _D), it is possible to obtain the traverse information for one track unit on the basis of the reproduction output (Q _E).

Thus, each of the above blocks (BL ₁ ), (BL ₂ ) to (BL
_n ) The control recording area (AR _C ) is divided into a servo area (AR _S ) and a traverse area (AR _T ), and the tracking information pits (Q _A ) and (Q _B ) and the clock information pit (Q _C )
In the optical disc (1) in which the traverse information pits (Q _D ) and the traverse information pits (Q _D ) provided in the traverse area (AR _T ) are linearly arranged in the servo area (AR _S ), respectively.
Since the relative distance P of (Q _E ) is shifted by one channel bit between adjacent tracks, and one of the pair of traverse information pits (Q _D ) and (Q _E ) is at the same position, When reading the traverse information by the information pits (Q _D ) and (Q _E ), a reading error can be easily confirmed, and the tracking information pits (Q _A ),
Based on the reproduced clock obtained from the clock information pit (Q _C ) under stable tracking control based on (Q _B ), the pair of traverse information pits (Q _D ),
By reading the bit pattern of (Q _E ), a high-accuracy traverse count can be performed for each recording track.

For example, as shown in FIG. 4, when the light spot (SP) by the optical head moves from point A to point E, points A and B
Each traverse information pits traverse information M showing a first N-th track in the points with respect to the traverse area _{(AR T) (Q D)} , is detected based on the reproduction output (Q _E), the (N + 1) at point D and point E Traverse information M indicating track number
+1 is detected based on the reproduced output of the traverse information pits (Q _D ) and (Q _E ), and stepwise traverse information for each track is obtained as shown in FIG.

In the optical disc (1), tracking error information in the track pitch direction of the recording track can be obtained based on the reproduction output of the tracking information pits (Q _A ) and (Q _B ). The position of each point between tracks can be known. Since the tracking error information is non-linear as described above, it does not become velocity information even when differentiated. For example, the tracking error information of a tracking servo device disclosed in Japanese Patent Application Laid-Open No. As described above, by forming the tracking error information proportional to the displacement of the recording track from the recording track in the track pitch direction, the frequency of the tracking error information is changed to the sampling frequency.
Even when the light spot crosses one track at a speed of 1/2 or more, the position of the light spot between tracks can be known from the tracking error information.

Therefore, for the optical disc (1), for example, as shown in FIG. 5, the step-like traverse information in units of one track is obtained by using the sawtooth wave-like tracking error information proportional to the displacement from the recording track (TK). By interpolating, it is possible to form information that continuously indicates the position of the light spot (SP), as indicated by a broken line in FIG.

That is, in FIG. 5, for example, traverse information at point A is k (0 ≦ k ≦ 15), the position between tracks at this time is T _Ea (−128 ≦ T _Ea ≦ 127), and the next sampling point The traverse information at the time of moving to the point B is 1 (0 ≦ l ≦ 15), and the position between the tracks is T _Eb (−128
When a ≦ T _Eb ≦ 127), the distance [Delta] x from A point to B point, the track pitch as _{T P, Δx = (l-} k) · T P + (T Eb -T Ea) · T P / 256 ... next first equation, 1 average velocity v of the light spot moves by [Delta] x between the sampling time T _S is, v = [Delta] x / T _S ... second equation becomes second indicated in formula above Determined at point B. Here, since the track pitch T _P and the sampling time T _S are fixed values, the average moving speed v of the light spot can be detected by measuring only l, k, T _Eb , and T _Ea .

FIG. 1 is a block diagram showing a servo system configuration of an optical disk recording / reproducing apparatus using the optical disk (1) having the above-described recording format as a recording medium.
The spindle motor (2) for rotating the optical disk (1) is provided with a spindle servo so as to rotate at a constant angular velocity.

The optical head (3) is driven by a laser driving circuit (4) to emit a laser beam, and a laser beam emitted by the laser diode is used to record a light spot by the objective lens on the recording track of the optical disc (1). The head amplifier (5) is provided with a built-in two-axis actuator that converges upward, a photodetector that detects the return light of the data light reflected by the optical disk (1), and the like, and outputs a detection output from the photodetector as a reproduction RF signal. Clock recovery circuit (6) and analog
It is supplied to a digital (A / D) conversion circuit (7).

The clock reproducing circuit (6) is provided with the optical head (3).
The clock reproduction by the so-called PLL is performed based on the reproduction output by the clock information pit (Q _C ) in the reproduction RF signal supplied from the above, and the clock for synchronizing the entire system and the latch timing clocks CK ₁ and CK ₂ are obtained. Form.

The A / D conversion circuit (7) converts the reproduced RF signal into 8-bit digital data, and converts the digital data into a traverse decoder (8), a tracking error signal generator (9), and a muting control circuit. Circuit (10)
To supply.

The traverse decoder (8) discriminates a pit pattern of a reproduction output by the traverse information pits (Q _D ) and (Q _E ) in the reproduction RF signal, and the optical head (3)
The traverse information indicating the scanning position of the light spot by one track unit is output as a 4-bit gray code value.

That is, in the traverse decoder (8), when the light spot (SP) by the optical head (3) moves from the point A to the point E in FIG. each traverse information pits of the traverse information M is the traverse region showing _{(AR T) (Q D)} ,
Is detected on the basis of the reproduction output (Q _E), the point D and point E traverse information M + 1 the traverse information pits indicating the first N + 1 th track (Q _D), it is detected based on the reproduction output (Q _E) You.

Traverse information obtained by the traverse decoder (8) is latched by the latch circuit (11) every sampling period T _S Racks clock CK _1, the traverse information latched in said latch circuit (11) is a latch circuit ( is further latched by the latch clock CK ₁ at the next sampling point by 12). Then, the difference between the traverse information latched by the latch circuits (11) and (12) is calculated by the subtractor (13), whereby the upper four positions of the distance Δx that the light spot has moved during one sampling period T _S are calculated. Calculate bit data.

The tracking error signal generator (9)
The tracking information pit (Q _A ) in the reproduced RF signal,
Based on the reproduction output (Q _B), to form the tracking error information V _X which is proportional to the displacement from the recording track (TK) in the track pitch direction of the recording track (TK) as follows.

That is, the tracking information pit (Q _A ),
As shown in FIG. 6A, a sinusoidal tracking error signal _VP is obtained as a signal level difference when the reproduced output of (Q _B ) is sampled and held. Further, in the reproduction output of the clock information pit (Q _C ), a change in signal level appears according to the tracking error. Level variation V _Q of the reproduction output of the clock information pits (Q _C), as shown in B of FIG. 6, has a 90 ° phase difference with respect to the tracking error signal V _P, given that, Therefore, the signal indicating the displacement x is expressed by V _X ′ as It is represented by the following fourth formula.

The signal V _X ′ is | x as shown by the solid line in FIG.
In the range of | <T _P / 4, it is proportional to the displacement x in principle, but | x |
= Discontinuous at T _P / 4. Therefore, T _P / 4 ≦ | x | <T _P /
By shifting the level of the signal V _X ′ in the range of 2 in the direction indicated by the arrow in FIG. 6C as indicated by the broken line in FIG. 6, | x | <T _{P as} illustrated in FIG. Displacement x in the range of / 2
It is possible to obtain a tracking error signal V _X which is proportional to.

The tracking error signal generator (9) is constituted by, for example, the above-described fourth equation of arithmetic processing and memory forming a conversion table of the tracking error information V _X of 8 bits obtained by the level shift processing.

Tracking error information V _X obtained by the tracking error signal generator (9) is supplied to the latch circuit (15) via a muting circuit (14).

The muting operation of the muting circuit (14) is controlled by the muting control circuit (10). As shown in FIG. 7, the tracking error information V obtained by the tracking error signal generator (9) is obtained. _X is subjected to a muting process near a change position of traverse information obtained by the traverse decoder (8).

Here, the muting control circuit (10) uses the traverse information of the current track obtained by the traverse decoder (8) and the traverse information of the next closest track to generate the tracking error signal generator (9). by evaluating the validity of the tracking error information V _X obtained by), performs the operation control of the muting circuit (14) performs muting processing at change position near the traverse information. That is, as shown in FIG. 7, for example, when the traverse information of the current track is “1”, it is determined whether the current position is close to the track 0 or to the track 2 and the tracking error contradictory thereto is determined. to perform the muting process if the information V _X is generated by the tracking error signal generator (9). For example, in the change position (A) near the traverse information in Figure 7, is close to the track 0, but it is given unlikely that tracking error information V _X of a level is detected, the traverse information and the tracking error since the information V _X is formed by the different detection processing system, due to the offset of each detection processing system, performs a muting process so such a condition occurs.

Thus the tracking error information V _X which has been subjected to muting process, by combining with the traverse information, as indicated by a thick solid line in FIG. 7, and thus no positional information resulting discontinuities. In the case where the tracking error information V _X without performing muting processing has been synthesized directly with the traverse information occurs discontinuity indicated by the imaginary line in FIG. 7, the noise this discontinuity portion of the access operation And hinders a stable access operation. However, as in this embodiment, by performing a muting process on the tracking error information V _X by the muting circuit (14), it is possible to remove the discontinuous portion.

Here, the above muting control circuit (10)
As shown in the figure, an emboss pit (P) is previously provided at a position offset by 1/2 track from the track center every two tracks on the recording surface of the optical disc, and the detection information of the emboss pit (P) and the traverse from Yadoriki偶information, by evaluating the validity of the tracking error information V _X obtained by the tracking error signal generator (9), resulting in the position information obtained by combining the tracking error information and the traverse information not It is also possible to detect a continuous portion and control the operation of the muting circuit (14) so as to remove the discontinuous portion.

Then, the tracking error information V _X which has been subjected to muting processing by the muting circuit (14),
Is latched by the latch circuit (15) every sampling period T _S at the latch clock CK _1, the latch circuit (1
Tracking error information latched in 5) is further latched by the latch clock CK ₁ at the next sampling point by the latch circuit (16). Then, the subtractor (17) calculates the difference data ΔV _X of the tracking error information latched by the latch circuits (15) and (16), and converts the difference data ΔV _X into the light spot during one sampling period T _S. Is the lower 8-bit data of the distance Δx that has moved.

Further, the subtracter (1) for calculating the difference data ΔV _X
The borrow flag 7) is given to the subtractor (18) to which the distance Δx is supplied, and the subtractor (18) corrects the distance Δx with the borrow flag.

The subtraction output data ΔV _X , Δx of each of the subtracters (17), (18) is supplied to a latch circuit (19).
The distance Δx corrected by the subtracter (18) is used as upper 4-bit data, and the difference data ΔV _X obtained by the subtracter (17) is used as lower 8-bit data, and the sampling period T _{S is used} by the latch circuit (19). It is latched on the latch clock CK ₂ in the form a 12-bit speed detection data v each.

Here, the latch clock CK ₂ is the latch clock C
Relative to K _1, the subtracter as shown in FIG. 9 (13),
A longer time delay than the calculation time of (17), (18), and (20) is given.

At the time of actual access, a changeover switch (22) for selecting a subtractor (20) provided on the output side of the subtractor (13) for calculating the distance Δx and a system controller (21) is provided. first select the system controller (21) initializes the distance x _o to be accessed from the system controller (21) to the latch circuit (23). Then, when the access is started, the changeover switch (22) selects the subtractor (20), and Δx obtained by the subtractor (13) is changed from the value x latched in the latch circuit (23). The above subtractor (2
0) by subtracting, latches the value to the latch circuit for each sampling period T _S in latch clock CK ₂ (23). As a result, the value x of the latch circuit (23) decreases by Δx every sampling period T _S. Then, 8 corresponding to the value x latched by the latch circuit (23)
The bit reference speed information v _REF is read from the reference speed information generation memory (24). The 8-bit reference speed information v _REF given by the reference speed information generation memory (24) is given to the subtracter (25), and the above-mentioned latch circuit (1
The difference v _e between the upper 8 bits of the 12-bit speed detection data v latched in 9) and the reference speed information v _REF is calculated as speed error information by the subtracter (25).
The speed error information v _e calculated by the subtractor (23) is
The signal is converted into an analog signal by a digital / analog (D / A) conversion circuit (26) and supplied to a phase compensation circuit (28) via a signal adder (27). It is supplied to the drive amplifier (29) that drives the feed linear motor of (3). Upper speed error information
The access by v _e is continued until the value x latched in the latch circuit (23) becomes zero. When the value x becomes zero, the changeover switch (22) is turned on by the system controller (21). To a state where the value x of the latch circuit (23) is held at zero,
Close the servo switches (34) and (35).

By the switch (34) is closed, the tracking error information obtained by the tracking error signal generator (9) v _X is the digital-to-analog (D / A) converter (30) into an analog signal conversion The output of the drive amplifier (32) supplied from the phase compensation circuit (31) forms a tracking servo loop so as to drive the tracking coil of the biaxial actuator of the optical head (3). With this tracking servo loop, the light spot of the laser beam of the optical head (3) can accurately follow the recording track (TK) on the optical disk (1).

Further, when the switch (35) is closed, a low-frequency component extracted from the output of the drive amplifier (32) by the low-pass filter (33) is passed through the signal adder (27) to the phase compensation circuit. (28) is supplied to the drive amplifier (29) for driving the head feed linear motor, and a phase servo loop is formed.

In this state, since the reference speed information v _REF given by the reference speed information generation memory (24) is also zero, a speed servo loop is also formed so that the access speed v becomes zero.

Accordingly, by performing such access control, any position on the optical disk (1) can be detected, and speed detection can be performed with high accuracy. Therefore, even if there is disturbance such as eccentricity of the optical disk, Thus, a target recording track can be always reached by one access operation.

H Effect of the Invention In the optical disk device according to the present invention, the recording track is set to 1
Based on a reproduction output by an optical head that scans a recording surface portion of an optical disk with an optical beam, in which traverse information indicated in track units is recorded in advance on each recording track, an amount of change in traverse information obtained every predetermined period is detected and accessed. By forming the high-order bit data of the speed and detecting the amount of change in the tracking error information to form the low-order bit data of the access speed, the access speed can be detected with high accuracy.

The access speed information formed from the traverse information and the tracking error information is obtained by performing a muting process on the tracking error information near a change position of the traverse information by a muting unit.
The discontinuity is removed, and high-accuracy speed information that does not generate noise or the like is obtained.

In addition, the tracking error information forming means forms the tracking error information proportional to the displacement of the recording track from the recording track in the track pitch direction, so that the frequency of the tracking error information becomes 1/2 or more of the sampling frequency. 1 light spot
Even when a track is traversed, the position of the light spot between the tracks can be known from the tracking error information, so that the access speed of the optical disk by the optical head moving at a high speed can be accurately detected.

Therefore, according to the present invention, it is possible to provide an optical disk apparatus capable of moving an optical head to a target track position and quickly and reliably recording and reproducing information on a target recording track.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a servo system of an optical disk device according to the present invention, FIG. 2 is a diagram showing a recording format of an optical disk used in the optical disk device, and FIG. FIG. 4 is a view showing the state of each pit provided, FIG. 4 is a view for explaining the reproduction state of the traverse information by the traverse information pits provided in the traverse area of the optical disk, and FIG. FIGS. 6A to 6D are diagrams for explaining the principle of operation for obtaining tracking error information proportional to the displacement from the track, and FIG. 7 is a diagram showing a muting circuit of the optical disk device. 8 is a waveform diagram for explaining the operation, FIG. 8 is a waveform diagram for explaining another operation example of the muting circuit, and FIG. Is a time chart for explaining the detection operation of the access speed to kick the servo system of the optical disk apparatus. FIG. 10 is a characteristic diagram showing an example of a conventional general optical head feed control when accessing a target recording track, FIG. 11 is a diagram showing a recording format of an optical disc employing sampled servo, FIG. FIG. 12 is a diagram showing the state of each pit provided in the control recording area of the optical disk, FIG. 13 is an explanatory diagram of an error due to the example of the optical head feed control, and FIG. 14 is an explanatory diagram of a tracking error. (1) Optical disk (3) Optical head (8) Traverse decoder (9) Tracking error signal generator (10) Muting control circuit (11), (12), (15) , (16), (19), (23) ...
Latch circuit (13), (17), (18), (20), (25): Subtractor (14): Muting circuit (44): Recording surface (TK): Recording track (Q _A ), (Q _B ) Tracking information pit (Q _C ) Clock information pit (Q _D ), (Q _E ) Traverse information pit (AR _C ) Control recording area (AR _D ) information writing region (AR _S) ...... servo region (AR _T) ...... traversing region

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 21/08 G11B 7/085

Claims (1)

(57) [Claims] An optical head scans a recording surface portion of an optical disk in which traverse information indicating a recording pattern in a circular pattern formed on the recording surface portion in one track unit is previously recorded on each recording track by an optical head. An optical disc device, comprising: traverse information detecting means for detecting traverse information for the optical disc from the recording track based on a reproduction output by the optical head; and a change amount of traverse information obtained at predetermined intervals by the traverse information detecting means. A first access speed information forming means for detecting higher-order bit data of an access speed by detecting a light spot of the optical beam in a track pitch direction with respect to a recording track on the optical disk based on a reproduction output by the optical head. Tracking error information proportional to displacement A tracking error information forming unit that performs a muting process on the tracking error information obtained by the tracking error information forming unit near a change position of the traverse information detected by the traverse information detecting unit; Second access speed information forming means for detecting the amount of change in the tracking error information subjected to muting processing by the muting means and forming the lower bit data of the access speed, wherein the traverse information and the muting processing are performed. An optical disk device characterized in that access control of an optical disk by an optical head is performed based on the tracking error information.