JPH03230376A - Optical disk device - Google Patents

Abstract

PURPOSE:To rapidly and surely record/reproduce information in/from an objective recording track by executing the access control of an optical disk by an optical head based upon traverse information and muted tracking error information. CONSTITUTION:When access is started, tracking error information DELTAx obtained by a subtractor 13 is subtracted from a distance (x) latched in a latch circuit 23 and the subtracted result is latched in the circuit 23. Reference speed information VREF corresponding to the value (x) s read out from a memory 24 and a difference between the upper bit data of speed detection data outputted from a latch circuit 19 and the information VREF is calculated by a subtractor 25 as speed error information Ve and supplied to the optical head 3 through an adder 7 and so on. Access based upon the information Ve is continued until the value (x) becomes zero, and when the value (x) goes to zero, switches 34, 35 are closed. When the switch 34 is closed, tracking error information Vx muted by a muting circuit 14 drives the tracking coil of the optical head 3.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an optical disc device in which a recording surface portion of an optical disc on which a circular pattern of recording tracks is formed is scanned with a light beam by an optical head.

B. Summary of the Invention The present invention provides an optical disc device in which a recording surface portion of an optical disc having a recording trunk in a circular pattern is scanned by an optical head using a light beam, and a traverse method that indicates recording tracks on the optical disc in units of l torano. Information is recorded in each recording trunk, and based on the reproduction output by an optical head that scans the recording surface of the optical disk with a beam,
The traverse information for the optical disc is detected from the recording track, and the amount of change in the traverse information obtained at predetermined intervals is detected to form upper bit data for access control. Forms tracking error information that is proportional to the position of the track in the direction of the recording track and track,
This tracking error information is subjected to muting processing near the position of change in the traverse information C, and by detecting the amount of change in the tracking error information subjected to the muting processing and forming lower bit data of the access speed, It is possible to accurately control access to an optical disk by an optical head from the traverse information and tracking error information subjected to muting processing.

C. Prior Art In recent years, optical discs using optical or magneto-optical signal recording and reproducing methods have been developed and are being supplied to the market. These optical discs include so-called CDs (
ROM (read-only memory) types such as compact disks, so-called write-once types that allow the user to write data once, and rewritable data such as magneto-optical disks. Recording media and the like that can be overridden (so-called override) are known.

In an optical disk device that uses an optical disk as a recording medium that uses an optical or magneto-optical signal recording/reproducing method, a spindle servo rotates the optical disk at a constant angular velocity or linear velocity while recording and reproducing information. A focus servo or a tracking servo is applied to an optical head that has a built-in laser diode that outputs a laser beam, a photodiode that detects the reflected light of the laser beam from the optical disk, etc., and the recording trunk of the optical disk is scanned with the laser beam. It is designed to record and play back information.

In addition, in the above-mentioned optical disk device, in order to move the optical head to a recording track position for the purpose of recording and reproducing information by scanning with a laser beam, for example, as shown in FIG. The moving speed V of the optical head is controlled so that, where X is the distance from the target track position PA, χ becomes the reference speed V at that time. Conventionally, the moving speed V of the optical head has been detected, for example, by a speed sensor fixed to a mechanical head.

This is a unified record for the various optical discs mentioned above7□
- As one of the techniques for realizing the matte, similar to the so-called sector servo in hard disks in the field of magnetic disks, servos are applied to concentric or spiral trunks on the disk at predetermined intervals or at a predetermined angle. Servo signals from clock pits, tracking pits, etc. are recorded at intervals (so-called preformat), and when the disk is driven to rotate, continuous servo control is performed by sampling and holding these discrete servo signals. A so-called sampled servo technique has been proposed.As this type of optical disk, for example, an optical disk (50) having a recording format as shown in FIG. 11 has been known.

In the optical disc (50) shown in FIG. 11, an annular label portion (52) is arranged around the central hole (51), and an annular recording surface portion (53) that extends around the label portion (52). ) is provided. The recording surface portion (53) has a spiral recording trunk (
tk) is provided, and each rotation, that is, one rotation trunk is divided into a predetermined number m (for example, m=32) of sectors (sc
+)+ (scz) ~ (scs),
For example, a plurality of sectors, such as sectors (scl) in each orbiting track, are arranged in a radial direction of the optical disc (50), and have a corresponding relationship between the respective orbiting tracks. The optical disc (50) provided with such a recording track (tk) is mounted in an optical disc device and rotated 63 times in the direction of arrow (r) to record or reproduce information using a light beam. served.

Each sector (scl) in each of the above-mentioned orbital tracks.

Each of (sc2) to (sc,) is provided with an address information section (ad) on its starting end side, and a recording track (tk) following this address information section (ad>).
It is assumed that a predetermined number n (for example, n=43) of blocks (bl,), (bl2) to (bl,) arranged in piles are included. The above blocks (bl,), (b
Regarding l□) to (bl,), for example, each sector (sc
, ), (scz) ~ (grounder in scJ (bl
, ), a plurality of blocks having a corresponding relationship between the respective sectors are arranged in the radial direction of this optical disc (50). Each of blocks (bl+), (blg) to (bl,) in each of these sectors (sc,), (sc,) to (sc,) is provided with a control recording area (ar=) on its starting end side. At the same time as the following information writing area (arゎ)
is provided to constitute a unit record division. Then, each of the above blocks (bL), (blg) to (
The control recording area (arc) of the track center 1 (k,) includes tracking information focuses (q,) and (q,), which are shifted outward and inward with the track center 1 (k,) in between, and the track center 1 (k,). Clock information pits (q,) located on the line (kC) are formed in advance at predetermined intervals along the track center line (k,). Also,
The track center line (k) of the trunking information pits (qa), (qb) and clock information pit (Qc)
c) in a direction orthogonal to the optical disc (50);
To explain the arrangement state in the radial direction, as shown in FIG. 12, the tracking information pits (q,) and the clock information pits (qc) are arranged linearly in the radial direction, whereas The tracking information pits (qa) are arranged such that their positions are shifted in the longitudinal direction of the track (tk), for example, every 16 tracks.

In this way, the tracking information pit (qa).

(ql) and clock information focus (q,) are provided in the control recording area (arc). Recording area (a
The above tracking information focus (qa), (qb
) and clock information pits (qc) are read by a light beam and used for various servos and clock generation.

In other words, the necessary timing clock is formed by performing clockwise reproduction from the reproduction output of the above-mentioned lock information pinot (qc), and the tracking position shifted outward and inward with the above track center * (kc) in between. Information pit (qa
), (q, ) to calculate the trunking error based on the playback output and perform tracking control, perform focus control based on the playback output of the mirror area, and furthermore, playback output of the tracking information pit (qs). teeth,
As described above, the arrangement in which the positions are shifted every 16 tracks is used to perform so-called traverse counting to determine the track number currently being scanned by the optical pickup.

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 head side does not represent the true speed at which the optical spot moves on the optical disk.

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

However, when sampled servo is used, due to the sampling theorem, trunk crossing detection cannot be performed unless the light spot crosses one track in a time that is more than twice the sampling period. The problem is that it cannot be detected.

Here, in the optical disc d shown in FIG. 11 mentioned above, the arrangement of the tracking information bits (q,) is shifted every 16 tones as described above and used for traverse counting. Since traverse counting can be performed in units of 16 trunks, it is possible to detect speed during high-speed movement using the traverse information in units of 16 trunks. However, when performing speed detection during low-speed movement, there is a problem that the phase is delayed due to dead time and hold time, making it impossible to perform highly accurate speed detection.

For example, as shown in No. 131m, when the true speed v0 of the light spot during deceleration is compared with the speed v4 detected from the traverse information, the time from point A to point B, which is 16 toranok ahead, is Tk- 3, the average speed for that section is determined, and this value is calculated from point A to T.
The true velocity v0 at the 0 point located at the advanced position of k-,/2
This value is determined at the 0 point after the dead time Tu+ (Tun=Tk-, /2) has elapsed from the point B, and is equal to D at the next 16 tracks.
It is held until the point. At the above point, there is a difference Δ between the true speed V0 and the speed v4 detected from the above traverse information.
error has occurred. The time from point B to point D becomes a phase delay of Tx1/2+Tk.

The above time Tk is the time during which the light spot travels 16 toranok. Therefore, when the moving speed of the light spot becomes slower, the time Tk becomes thicker, the speed detection error also becomes larger, and even when the target track is reached after the access is completed, the speed does not become zero and a large overshoot occurs. This is similar to one-track counting at low speeds or one-track counting of continuous servo, and the speed cannot be detected while one trunk is advancing.

Further, since the tracking error signal is normally non-linear as shown in FIG. 14, even if it is differentiated, it does not become a speed signal.

As described above, in conventional optical disk devices, when moving the optical head to the target track position and recording/reproducing information on the target recording track, it is not possible to detect the access speed with high accuracy. There was a problem in that the target trunk could not be reached after , - number of access operations, resulting in a long access time.

Therefore, in view of the above-mentioned conventional problems, the present invention provides an optical disc device that can move an optical head to a target track position and quickly and reliably record and reproduce information on a target recording track. The purpose is to offer.

E: Means for Solving Problem J Therefore, in order to solve the above-mentioned problems, the present invention provides traverse information indicating the circular pattern of recording tracks formed on the recording surface section in units of trunks for each recording. The optical disc device is arranged so that an optical head scans the recording surface portion of an optical disc prerecorded in a trunk with a light beam, and the traverse information for the optical disc is detected from the recording track based on the playback output from the optical head. traverse information detecting means; first access speed information forming means for detecting the amount of change in traverse information obtained every predetermined period by the traverse information detecting means to form upper bit data of an access speed; tracking error information forming means for forming tracking error information proportional to the displacement of the light spot by the light beam in the trunk pitch direction with respect to the recording track on the optical disk based on reproduction output; and tracking obtained by the tracking error information forming means. A muting means performs muting processing on the error information at a change value of 1 in the traverse information detected by the traverse information detection means, and a variation amount of the tiger and king error information subjected to the muting processing by the muting means. and second access speed information forming means for detecting and forming lower bit data of the access speed, and controlling access to the optical disk by the optical head from the traverse information and the tracking error information subjected to the muting process. It is characterized by the following.

F-Function In the optical disk device according to the present invention, traverse information indicating each track is recorded based on the reproduction output by an optical head that scans the recording surface portion of the optical disk with a light beam, in which traverse information is recorded in each recording track in advance. A detection means detects traverse information for the optical disk from the recording track, and a tracking error information forming means generates tracking error information proportional to a displacement of a light spot by the light beam in a track pinch direction with respect to a recording track on the optical disk. Form.

The traverse information provides position information for each track, and the tracking error information provides position information within one track.

Since the traverse information and the tracking error information are formed by different means, the position information shown by combining them has discontinuities due to offsets, /ts, etc.

The muting means removes the discontinuity by performing a muting process 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.

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 upper bit data of the access speed. Furthermore, the second access speed information forming means detects the amount of change in the trunking error information subjected to the muting process by the muting means and forms lower bit data of the access speed. The tracking error information detected from the playback output by the optical head that scans the recording surface of the optical disk with a light beam is nonlinear, so even if it is differentiated, it does not become velocity information. However, the tracking error information forming means By forming trunking error information proportional to the displacement number of the recording track from the recording track in the track pinch direction, the frequency of the trunking error information is at least 1/2 of the sampling frequency. Even if the light spot crosses one line, the position of the light spot 7) between the trunks can be known from the trunking error information.

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

The block diagram in FIG.
Optical disc (1) with a recording format as shown in Figures 2 and 3, which was previously proposed by the applicant as No. 2.
2 shows the configuration of a servo system when the present invention is applied to an optical disc device that uses a disc as a recording medium.

The optical disc (1) used in this optical disc device has a second
As shown in the figure, an annular leher part (42) is arranged around the central hole (41), and this leher part (42)
An annular recording surface portion (44) extending around the periphery is provided. The recording surface portion (44) has the central hole (
A spiral recording track (TK) forming a large number of circular patterns surrounding the 41) is provided, and each rotation of the spiral recording track (TK)
That is, the number of trunks in one rotation is a predetermined number m (for example, m=3
2) Sectors (Set), (SCz) ~ (SC,) are divided into sectors (Set), (SCz) to (SC,). sectors are arranged in the radial direction of this optical disc (1). Each sector (SC,) in each of the above orbiting tracks,
(SC,) is arranged with an address information division (AD) on its starting end side, and is arranged along a recording track (TK) following this address information division (AD). It includes a predetermined number n (for example, n=43) blocks (BL, ), (BL,) to (BLll). Regarding the blocks (BLI) and (BLll) to (BLll), , for example, each sector (Set),
Block (BL l in (Set) ~ (SC,)
), a plurality of blocks having a corresponding relationship between the respective sectors are arranged in the radial direction of this optical disc (1). Each such sector (
SC+), (SCz) ~ (SC,) block (
at+), (etg) to (BL, ), a control recording area (ARc) is provided on the start end side, and an information writing area (ARo) following it is provided, forming a unit recording section. do.

Then, each of the above blocks (BL+), (BLz) to (B
The control recording area (ARc) of the servo area (A
The servo area (ARs) is divided into a pair of trunking information bits (QA) and (Q,) at a predetermined interval in the track direction (in this example, 8 channel bits). ) apart from each other by 1/4 track pitch on both sides of the track center line (Kc).
(QA), (Q,) and is placed on the trunk center line (K,), and the traverse area (ARo) has a pair of traverse information bits (Q,).
D) and (QE) are spaced apart by a distance P assigned to each recording track based on the clock information focus (Qc).

Here, each of the control recording areas (ARc) has a data recording capacity of 30 channel bits,
The above tracking information bit (QA).

The recording position of (Q,) is the 7th channel, g, and 1st channel.
In addition, the 11th channel bit is assigned as the recording position of the clock information focus (QC), and the traverse information pit (
The 19th channel bit to the 27th channel bit are allocated as the recording area for QD) and (Q-). And the above tracking information bits (QA), (Ql)
, Kuro, Ri information pi.

(Qc) and traverse information pit (QD), (QE
) in the direction perpendicular to the trunk center line (Kc), that is, the radial direction of the optical disc (1). As shown in the third circle, the tracking information bits (QA), (Ql) and clock Information pit (Q
C) are arranged linearly in the radial direction, whereas the traverse information pits (Qo) and (Qt)
, one traverse information pit (QD) is shifted in the track direction by one channel bit in units of 4 tracks, and the other traverse information pit (Q, )
The above traverse information pin (Ql) is shifted by 1 in the track direction by 1 channel bit for each track, except for the part where the position changes in units of 4 tracks, and 16
Each track is a unit, and each track has a different bit pattern.

In the optical disc (1) of the recording formant as described above,
Traverse information for each track can be obtained based on the reproduced output of the traverse information bits (Q,), (Q,).

In this way, each of the above blocks (BL+), (Bt, x
) to (BLll) are divided into a servo area (ARs) and a traverse area (ARt), and the tracking information focus (QA), (Ql) is divided into a servo area (ARs) and a traverse area (ARt).
and clock information Pino) (QC) to the above servo area (AR
In the optical disk (1) which is arranged linearly in the radial direction in 5), the relative path i1P of the traverse information pins (QC) and (QE) provided in the traverse area (ARt) is one channel between adjacent tracks. It is shifted by the length of the grass pit, and there is also a pair of traverse information pits (Q,)
, (Q,) is at the same level I, so when reading the traverse information from the traverse information pits (Q, o) and (Qt), reading errors can be easily confirmed, and the tracking Information pit (QA) (Q
, ) of the pair of traverse information pits (QD) based on the reproduced clock obtained from the clock information focus (QC) under stable tracking control based on
By reading the bit pattern of (QE), it is possible to perform highly accurate traverse counting of recording tracks in units of one trunk.

For example, when the optical spot (SP) by the optical head moves from point A to point E as shown in FIG.
At point D and E, traverse information M indicating the Nth track is detected based on the playback output of each traverse information Pino) (Qo) and (Qt) for the traverse area (ARo), and at point D and E, the N+1th track is detected. The traverse information M+1 indicating the above is the traverse information Pino) (QD)
, (Qi), and step-like traverse information for each trunk is obtained as shown in FIG.

Further, 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 focus (Qc), and as this tracking error information, You can know the location of The above tracking error information is non-linear as mentioned above, so even if it is differentiated, it does not become speed information. As shown in FIG. Even when tracks are crossed, the position of the light spot between tracks can be known from the track and king error information.

Therefore, for the optical disc (1), for example, the fifth
As shown in the figure, by interpolating the stepped traverse information in l-track units with sawtooth tracking error information proportional to the displacement from the recording trunk (TK), as shown by the broken line in the figure, Optical socket (SP)
It is possible to form information that continuously indicates the position of.

That is, in FIG. 5, for example, the traverse information at point A is k (0≦≦15), the position between the trunks at this time is Ti, (-128≦Ttm≦127), and the next sampling point 8 Assuming that the traverse information when moving to a point is 1 (0≦2≦15) and the position between trunks is Ttb (128≦Ttb≦127), the distance ΔX from point A to point B is the track pitch T
, as Δx=(1-k)・T.

+ (Ttb TEA) ・T, /256...
The average velocity V of the light spot moving by ΔX during one sampling time T is expressed by the second equation, V-Δx /T t . . ., and is determined at the point B above. Ru.

Here, since the track pitch T and sampling time T are fixed values, II! , k, Ttb
If only TEa is measured, the average moving speed of the light spot V
can be detected.

Then, an optical disc (1
) in the block diagram of FIG. 1 showing the configuration of a servo system of an optical disc recording/reproducing apparatus using an optical disc (1) as a recording medium, a spindle motor (2) that rotates the optical disc (1);
is equipped with a sveendl servo so that it rotates at a constant angular velocity.

The optical head (3) also includes a laser diode that is driven by a laser drive circuit (4) to emit laser light, and a light spot of the laser light emitted by the laser diode that is directed onto the recording track of the optical disc (1) using an objective lens. It has a built-in two-axis actuator for converging the data light upward, a photodetector for detecting the return light of the data light reflected by the optical disk (1), etc., and the detection output from the photodetector is used as a reproduction RF signal to be sent to the head amplifier (5). The clock regeneration circuit (6) and the analog
It is supplied to a digital (A/D) conversion circuit (7).

The clock regeneration circuit (6) performs clock regeneration using a so-called PLL based on the regeneration output from the clock information focusing (QC) in the regeneration RF signal supplied from the optical head (3). Synchronizing clocks and latch timing clocks CK, CKt are formed.

Further, the A/D conversion circuit (7) converts the reproduced RF signal into 8-bit digital data, and transmits this digital data to the traverse decoder (8), the tracking error signal generator (9), and the muting control circuit. Circuit (1
0).

The traverse decoder (8) determines the scanning position of the optical spot by the optical head (3) by determining the bit pattern of the reproduction output based on the traverse information (QD) and (Q) in the reproduction RF signal. The trough information indicated in units of one track is output as a 4-bit gray code value.

That is, in the traverse decoder (8), the optical subsystem (SP) by the optical head (3) is
When moving from point A to point E in the diagram, point A and B
At the point, traverse information M indicating the N-th trunk is stored in each traverse information pit (Q) of the traverse area (ART).
D), (Detected based on the playback output of Q, and the N+1th tiger at point D and point E.

Traverse information M+1 indicating the traverse information is detected based on the reproduced output of the traverse information pits (Qo) and (Qt).

The traverse information obtained by the traverse decoder (8) is latched by the rank clock (J) every sampling period T by the launch circuit (11), and the traverse information latched by the launch circuit (11) is latched by the launch circuit (11). According to (12), it is further latched with the latch clock CL at the next sampling point.
Each of the above latch circuits (11).

By calculating the difference in the traverse information latched by (12) using a subtracter (13), the upper 4 bit data of the distance ΔX that the light spot has moved during one sampling period T is calculated.

The tracking error signal generator (9) also includes tracking information (QA) in the reproduced RF signal;
Based on the playback output of (Ql), record track (T)
The recording track (TK) in the track pitch direction of
Tracking error information (8) proportional to the displacement from ) is formed as follows.

That is, the tracking information focus (Q,).

As a signal level difference when the reproduced outputs of (Q, ) are sampled and held, a sinusoidal tracking error signal (2) as shown in A in FIG. 6 is obtained. Further, in the reproduced output of the clock information pit (Q,), a change in signal level appears in accordance with the tracking error. Level change v0 of the playback output of the above clock information pit (Q,)
As shown in B of FIG. 6, has a phase difference of 90° with respect to the tracking error signal V, and Vo=Acos(2+r-)...Third formula % formula %) Therefore, the signal indicating the displacement X is V8'...
It is expressed by the fourth equation, which is the fourth equation.

The signal Vx' is, as shown by the solid line C in FIG.
In principle, it is proportional to the displacement X in the range of i x 1 < TP/4, but it is discontinuous at l x l = Tp/4. Therefore, Tde/4≦l x I <Tp/2
By level-shifting the signal vX' in the direction shown by the arrow in FIG. 6C in the range of 1x1<TP/2 as shown in FIG. 6D, A tracking error signal 8 proportional to the displacement X can be obtained.

The tracking error signal generator (9) is constituted by a memory in which is formed a conversion table of tracking error information v, l of 8 points obtained by, for example, the arithmetic processing of the above-mentioned formula 4 and the above-mentioned level shift processing.

The tracking error information (1) obtained by the tracking error signal generator (9) is supplied to the latch circuit (15) via the muting circuit (14).

The muting operation of the muting circuit (14) is controlled by the muting control circuit (10?), and as shown in FIG. The information vX is subjected to muting processing near the change in the traverse information obtained by the traverse decoder (8).

Here, the muting control circuit (10) calculates the track 1. Tracking error information vIl obtained by the king error signal generator (9)
By evaluating the validity of When the track traverse information is "1", it is determined whether the current position is close to track 0 or track 2, and the tracking error signal generator (9) generates tracking error information v8 that is inconsistent with the current position. For example, in the vicinity of the change value If (A) of the above traverse information in FIG. 7, since it is close to track O, tracking error information 8 of level a is detected. However, since the above traverse information and tracking error information (8) are formed by different detection processing systems, such a state occurs due to offsets of each detection processing system, so muting is not possible. Apply processing.

By combining the tracking error information (8) subjected to the muting process with the traverse information described above, it becomes position information without any discontinuous portions, as shown by the thick solid line in FIG. Note that if the tracking error information V is directly combined with the traverse information without performing muting processing, a discontinuous portion shown by an imaginary line in FIG. 7 will occur, and this discontinuous portion will be the noise of the access operation. This becomes a cause of hindering stable access operations. However, as in this embodiment, the tracking error information vl is generated by the muting circuit (14).
By applying muting processing to l, the discontinuous portion can be removed.

Here, the muting control circuit (lO) has an eighth
As shown in the figure, embossed bits (P) are provided in advance on the recording surface of the optical disc at positions offset by 1/2 track from the track center every two tracks, and the detection information of these embossed bits (P) is By evaluating the validity of the tracking error information V obtained by the tracking error signal generator (9) based on the oddness or evenness of the traverse information, it is possible to determine the errors that occur in the position information obtained by combining the tracking error information and the traverse information. It is also possible to control the operation of the muting circuit (14) so as to detect a continuous portion and remove the discontinuous portion.

Then, the tracking error information v, I is subjected to muting processing by the muting circuit (14).
is latched by the latch circuit (15) at the latch clock CK every sampling period T, and the tracking error information latched by the latch circuit (15) is output to the latch clock CK at the next sampling point by the latch circuit (16). CM.

There will be more lunch. Then, each of the above latch circuits (1
5), The difference data Δv8 of the tracking error information launched by (16) is calculated by the subtractor (17), and this difference data Δ■ is calculated as the above-mentioned distance ΔX that the light spot has moved during one sampling period T. This is the lower 8 bit data.

Further, the subtracter (1
The borrow flag 7) is given to a subtracter (18) to which the distance ΔX is supplied, and the distance ΔX is corrected by the borrow flag by this subtracter (18).

The subtracted output data Δv, .
Let X be the upper 4 bit data and the subtracter (17
) is latched as lower 8-bit data by the latch circuit (19) every sampling period Ts, thereby forming 12-bit speed detection data V.

Here, ``the latch clock CKt is the subtracter (1) with respect to the latch clock CK, as shown in FIG.
A time delay longer than the calculation time of 7) is given.

Furthermore, during actual access, a changeover switch (22) is used to select between the subtracter (20) provided on the output side of the subtracter (13) that calculates the distance ΔX and the system controller (21). First, the system controller (21) is selected, and the distance X to be accessed from the system controller (21) is initially set in the latch circuit (23). Then, when access is started, the changeover switch (22) selects the subtracter (20), and ΔX obtained by the subtracter (13) is converted to the value X latched in the launch circuit (23). is subtracted from by the subtracter (2'O), and the value is latched into the latch circuit (23) at the rough clock CKI every sampling period T. As a result, the value X of the latch circuit (23) becomes Δ every sampling period T.
It decreases by χ.

Then, 8-bit reference speed information vllEF corresponding to the value X latched in the latch circuit (23) is read out from the reference speed information generation memory (24).

The 8-bit reference speed information VIItF given by the reference speed information generation memo IJ (24) is input to the subtracter (25).
), and the difference V between the upper 8 bits of the 12-bit speed detection data V, which is latched in the launch circuit (19) mentioned above, and the reference speed information V□ is subtracted as the speed error information. Calculated by the device (25). The speed error information V calculated by the subtracter (23) is converted into an analog signal by a digital-to-analog (D/A) conversion circuit (26) and then sent to a phase compensation circuit (27) via a signal adder (27). 28), and from this phase compensation circuit (28), it is supplied to a drive amplifier (29) that drives the linear motor for feeding the optical head (3). Access using the speed error information V continues until the value X latched in the latch circuit (23) becomes zero, and when the value Switch to the controller (21) side to maintain the value X of the latch circuit (23) at zero, and also switch the servo system switch (34)
, close (35).

Then, by closing the switch (34), the tracking error information vX obtained by the tracking error signal generator (9) is converted into an analog signal by the digital-to-analog (D/A) conversion circuit (30). The output of the drive amplifier (32), which is supplied from the phase compensation circuit (31)
A tiger/two-king servo loop is formed to drive the tracking coil of the two-axis actuator of 3). This tracking servo loop allows the optical spot of the laser beam of the optical head (3) to accurately follow the recording track (TK) on the optical disk (1).

Furthermore, by closing the switch (33), the low frequency component extracted by the low pass filter (33) from the output of the drive amplifier (32) is passed through the signal adder (2γ) to the phase compensation circuit. The signal is supplied from (28) to the drive amplifier (29) that drives the linear motor for radial feed, forming a phase servo loop.

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.

Therefore, by controlling access in this way,
Any position on the optical disc (1) can be detected,
Since the speed can be detected with high accuracy, even if there is a disturbance such as eccentricity of the optical disk, the target recording track can always be reached in a single access operation.

Based on the playback output from the optical head that scans the edge surface with a light beam, the amount of change in traverse information obtained at predetermined intervals is detected to form upper bit data of the access speed, and the amount of change in tracking error information is detected. By detecting and forming lower bit data of the access speed, the access speed can be detected with high precision.

The discontinuity of the access speed information formed from the traverse information and the tracking error information is removed by muting the tracking error information near the change position of the traverse information using a muting means. This provides highly accurate speed information without generating noise.

Moreover, by forming the tracking error information proportional to the displacement of the recording trunk from the recording track in the track pitch direction by the trunking error information forming means, the frequency of the tracking error information becomes 1/2 or more of the sampling frequency. The light spot is 1 at the speed
Even when crossing a track, the access speed of the position of the optical spot between trunks can be accurately detected.

Therefore, according to the present invention, it is possible to move the light to the target track position 1.
It is possible to provide an optical disc device that can quickly and reliably record and reproduce information on a target recording track.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing the configuration of the servo system of the optical disc device according to the present invention, Fig. 2 is a diagram showing the recording format of the optical disc used in the optical disc device, and Fig. 3 is the above-mentioned one. FIG. 4 is a diagram showing the state of each pit provided in the control recording area of the optical disc, and the reproduction of traverse information by the traverse information pits provided in the traverse area of the optical disc is proportional to the displacement from the track. Figure 7 is a diagram for explaining the operating principle for obtaining tracking error information. FIG. 8 is a waveform diagram for explaining another example of the operation of the muting circuit, and FIG. 9 is a waveform diagram for explaining the operation of the muting circuit. FIG. 9 is a waveform diagram for explaining the operation of the muting circuit. 5 is a time chart for explaining a speed detection operation. FIG. 10 is a characteristic diagram showing an example of conventional general optical head feed control when accessing a target recording track.
Figure 1 is a diagram showing the recording format of an optical disc that employs sampled servo, Figure 12 is a diagram showing the states of each focus provided in the control recording area of the optical disc, and Figure 13 is a diagram showing the state of each focus provided in the control recording area of the optical disc.
FIG. 14 is an explanatory diagram of errors caused by the above example of optical head feed control, and FIG. 14 is an explanatory diagram of tracking errors. (1) ...... Optical disk (3) ...... Optical head (8) ... Traverse decoder (9)
...... Tracking error signal generator (10
)・・・・・・・・・ Muting control circuit (IIL
(12), (15L(16), (23)...Latch circuit (13), (17), (18), (2
0)・・・・・・・・・Subtractor (14)・・・・・・
・ Muting circuit (44)... Recording surface section (TK)... Recording trunk (Q, ), (Q
, )... Trunking information pit (Qc)...
...Clock information pit (Qe), (QE)...
Traverse information pit (ARC)...Control recording area (ARo)...Information writing area (ARs) Servo area (ARA) Traverse area

Claims (1)

[Scope of Claims] An optical head scans a recording surface portion of an optical disk in which traverse information indicating, one track at a time, a circular pattern of recording tracks formed on the recording surface portion is recorded in each recording track in advance. an optical disc device comprising: traverse information detection means for detecting traverse information for the optical disc from the recording track based on reproduction output from the optical head; and changes in the traverse information obtained at predetermined intervals by the traverse information detection means. first access speed information forming means for detecting the amount of access speed and forming upper bit data of the access speed; and a track pitch direction of the optical spot of the optical beam with respect to the recording track on the optical disk based on the reproduction output of the optical head. tracking error information forming means for forming tracking error information proportional to the displacement of the tracking error information, and muting processing performed 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. a second access speed information forming means that detects the amount of change in the tracking error information subjected to the muting process by the muting means and forms lower bit data of the access speed; An optical disc device characterized in that access control of an optical disc by an optical head is performed based on traverse information and tracking error information subjected to muting processing.