JPH04205730A - Optical disk device - Google Patents

Abstract

PURPOSE:To increase the recording capacity of an optical disk by integrating a focus error signals, sample-holding to a sample-hold means, using its output as the focus error signals, thereby performing a focusing servo control. CONSTITUTION:The focus error signals SFOE obtained by scanning the servo area ARS of an optical disk with an optical head are integrated with the integration circuit 41 in a head servo circuit; its output is sample-held in the capacitor 47 of the sample-hold circuit 45, the output is used as the focus error signals SHOUT, and the focusing servo control is performed. Also, in the servo area ARS, a clock information pit QCK is provided on the center position of a track, simultaneously tracking information pits QWB1, QWB2 are provided on N-1 places excluding the center position of the tracking at a position PT/N with a track pitch as PT, and the signal level of signal SHOUT is fixed. Thus, the overhead in the servo area ARS is reduced, and the recording capacity of the optical disk is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Application Field The present invention provides a disk drive system in which servo areas and data areas are provided alternately along the head scanning direction, and the servo areas and data areas are arranged radially from the center of the disk. In addition, a sample servo format optical disk in which a plurality of tracking information pits for detecting the direction and amount of deviation from the track center and clock information pits for clock reproduction are formed in advance in the servo area is used as a recording medium. The present invention relates to an optical disc device for use.

B. Prior Art In recent years, optical discs using optical or magneto-optical signal recording and reproducing methods have been developed and are being put into practical use. These optical disks include ROM (read only memory) types such as so-called CDs (compact disks), so-called write-once types that allow the user to write data only once, magneto-optical disks, etc. There are known recording media that allow data to be rewritten (so-called override), such as the following.

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, the spindle servo does not rotate the optical disk at a constant angular velocity or linear velocity. A focus servo or a tracking servo is applied to an optical head that has a built-in laser diode that outputs light and a photodiode that detects the reflected light of the laser beam by the optical disk, and the recording track of the optical disk is scanned with the laser beam to obtain information. I am trying to record and play.

In addition, as one of the technologies for realizing a unified recording format for the various optical disks mentioned above, similar to the so-called sector servo in hard disks in the field of magnetic disks, a Servo signals such as clock information pits and tracking information pits are recorded at predetermined intervals or at predetermined angles (so-called preformat), and these discrete servo signals are sampled and held when the disk is driven to rotate continuously. A so-called sample servo technique has been proposed, which performs servo control. As this type of optical disk, for example, a sample servo format optical disk 5o as shown in FIG. 7 is conventionally known.

In the optical disc 50 shown in FIG. 7, concentric recording tracks tk forming a large number of circular patterns are provided on the recording surface portion 51, and each of the concentric recording tracks tk forms a large number of circular patterns.
The orbiting track is divided into a predetermined number m (for example, m=32) of sectors SCI, SC2 to scm. The sectors are arranged in the radial direction of the optical disc 5o. Then, such a recording track t
The optical disc 50, which is provided with k optical discs, is mounted in an optical disc device and rotated in the direction of arrow r, and is used for recording or reproducing information using a light beam.

Each sector SC++SC2 in each of the above-mentioned orbital tracks
~SC, is provided with an address information section ad on its starting end side, and this address information section ad
A predetermined number n arranged along the recording track tk following
(For example, r+-43) blocks bl,, bl□~
bl. The above block bl,
For b12 to b1□, for example, each sector SC,,s
A plurality of blocks having a corresponding relationship between the respective sectors, such as block bl in c2 to SC□, are arranged in the radial direction of this optical disc 50. Each sector Scl, sc2 to SC□
Each of the blocks b11 and b12 to bl is provided with a servo area ars on its starting end side, and a data area arD following it, constituting a unit recording section. In the servo area ars of each block bl+, bL to bln, a mirror area MA corresponding to 2N+1 channel pits is formed with N channel pits at intervals that do not cause code amount interference, and the track center line Tracking information pits QWB+ and qVIB located outside and inside with kc in between, shifted by 1/4 of the track pitch t.
2 and the clock information pit qCK located on the track center line kc are formed in advance along the track center line kc with an interval of N channel pits so as not to cause code amount interference with each other. ing. In this way, the tracking information pit qw+++qWB2 and the clock information pit I-qcK are placed in the servo area ars.
When the optical disc 50 provided in the servo area ars is loaded into an optical disc device and used for recording or reproducing information using a light beam, the tracking information pit QWBIIq□2 and the clock information pit q in the servo area ars.

K is read by a light beam and used for various servos and clock generation. That is, a clock is reproduced from the reproduced output of the clock information pit qcx to form a necessary timing clock, and reproduction is performed for the tracking information pit qwBI + qWB2, which is shifted outward and inward across the l-rack center line kc. Tracking control is performed by determining a tracking error based on the output, and focus control is performed based on the reproduced output of the mirror area MA. Furthermore, the playback output of the tracking information pit QWB+ is as described above.Using the arrangement in which the positions are shifted every 161-rack, the optical pickup performs so-called traverse counting to determine the track number currently being scanned. It is used in

Various methods such as the astigmatism method and the Knifezi method are known as methods for detecting the focus error.

C Problems to be Solved by the Invention In a conventional optical disk device that uses the conventional sample servo format optical disk 50 as a recording medium as described above, the interval at which no code amount interference occurs is defined as N channel pits, and the interval is 2N+1. Since clock reproduction was performed based on the reproduction output from the servo area ars formed from the mirror area MA for the channel pit, and focus servo control and tracking servo control were performed, at least (5N+1) was applied to the servo area ars.
There is a problem in that an overhead for each channel is required, and the amount of data that can be recorded in the data area is reduced by that amount.

In view of the above-mentioned conventional problems, the present invention provides that servo areas and data areas are provided alternately along the head scanning direction, and the servo areas and data areas are arranged radially from the center of the disk. In addition, a sample servo format optical disk in which a plurality of tracking information pits for detecting the direction and amount of deviation from the track center and clock information pits for clock reproduction are formed in advance in the servo area is used as a recording medium. The present invention aims to increase the recording capacity of the optical disk, and provides an optical disk device that reduces the overhead of the servo area and can reliably perform focus-a-ho.

D. Means for Solving the Problems Therefore, in order to solve the above-mentioned problems, the present invention provides that servo areas and data areas are provided alternately along the head scanning direction, and that the servo areas and data areas are provided alternately along the head scanning direction. are arranged radially from the center of the disk, and a plurality of tracking information pits for detecting the direction and amount of deviation from the track center and clock information pits for clock reproduction are formed in advance in the servo area. In an optical disc device that uses a servo format optical disc as a recording medium, the clock information pit for clock reproduction is provided at the track center position, and the track center position is excluded at a position PT/N where the track pitch is Pl ( N-1) An optical disc having a servo area in which the tracking information pit is provided at a location is used as a recording medium, and a focus error signal obtained by an optical head that scans a recording track of the optical disc is integrated during a scanning period of the servo area. and a sample hold means for sample-holding the integral output by the integrating means at the end of scanning the servo area,
The present invention is characterized in that focus servo control is performed using the sample hold output from the sample hold means as a focus error signal.

E-action In the optical disc device according to the present invention, the focusing error signal obtained by scanning the servo area of the optical disc with the optical head is integrated by the integrating means, the integrated output is sample-held by the sample-holding means, and the sample-holding output is Focus servo control is performed as a focus error signal.

In the servo area of the optical disk, a clock information pit for clock reproduction is provided at the track center position, and (N-1) locations other than the track center position are provided at positions P T / N where the track pitch is P. By providing a tracking information pit in (), the signal level of the focus error signal obtained as the sample hold output by the sample hold means, that is, the focus error level, becomes constant.

F Example Hereinafter, an example of an optical disc device according to the present invention = 11
− will be explained in detail with reference to the drawings.

The optical disc device according to the present invention is configured as shown in the block diagram of FIG. 1, for example.

This optical disk device uses a sample servo format optical disk 10 as a recording medium, scans the recording surface 11 of the optical disk 10 with a light beam using an optical head 20, and then records information magneto-optically using a magnetic spatula l' 21. 1. Information recorded on the recording surface of the optical disk 10 is read and reproduced by the optical head 20. Information is recorded and reproduced while the recording surface of this optical disk IO is scanned with a light beam by the optical head 20. The present invention is applied to a recording/reproducing device.

In this optical disk device, as shown in FIG. 2, servo areas ARs and data areas AR are provided alternately along the longitudinal direction of the recording track scanned by the optical head 20 with a light beam, that is, along the head scanning direction. The servo area ARs and the data area AR are arranged radially from the center of the disk, and include a clock information pit QCK for clock reproduction and a pair of tracking information pits QVIBII for detecting a tracking error.
An optical disk 10 of QWBI or a sample servo format previously formed in the servo area ARs is used.

That is, the optical disc 10 has concentric recording tracks T forming a large number of circular patterns on its recording surface 11.
K is provided, and each round, that is, one round of tracks or a predetermined number m (for example, m=32) of sectors sc, , s
It is divided into c2 to SC0, and is a plurality of sectors in a corresponding relationship between the respective orbiting tracks, such as sector SC0 in each orbiting track, for example, or
They are arranged in the radial direction of this optical disc 10. Each sector sc in each of the above orbiting tracks,
Each of sc2 to SC1 has an address information section AD arranged on its starting end side, and a predetermined number n (for example, n=43) arranged along the recording track TK following this address information section AD. Blocks BL,,BL
2~BL.

This includes: The above block BL.

BL2~BL. For example, each sector sc,,s
Block BL in c2-SC0.

A plurality of blocks having a corresponding relationship between the respective sectors are arranged in the radial direction of the optical disc 10, as shown in FIG. Each such sector sc,
, block BL in sc2-SCゎ, BL2-B
Each of L has a servo area AR11 on its starting end side.
A data area ARo is provided following the data area ARo, thereby forming a unit recording section.

Servo area A of each of the above blocks BL, BL2 to BLゎ
R8 consists of a recording area for (4N+3) channel pits with an overhead of 4N channel pits, where N channel pits are set at a distance that does not cause code amount interference, and the central channel pit is assigned to the clock information pit QCK. This clock information pit Q. A pair of tracking information pits QVIBI for each channel hit located N channel pits away from KC.
and Q Assigned to WB2. The clock information pit QCK is arranged and formed on the track center line Ke, and the pair of tracking information pits L-
Q WB 1 and Q w B 2 are this optical disc 1
The track pitch of 0 is defined as P7, and the racks are arranged so as to be shifted by 1/31-rack pitch PT/3 to the outside and inside, respectively, with the track center line Ke in between.

In the optical disc device of this embodiment which uses the above-described sample servo format optical disc 10 as a recording medium, the optical disc IO is rotationally driven by a spindle motor 22 at a constant angular velocity (CAV).

This optical disk device receives data D16. input to the data input terminal 23. The optical head 20 is equipped with an encoder 24 that converts the data into recording data having a predetermined data structure.

While scanning the optical beam, the encoder 24 applies a recording current corresponding to recording data to the magnetic head 2.
1, the recording surface 11 of the optical disc 10 is
Information is recorded on the recording surface 11, and the information recorded on the recording surface 11 is read and reproduced by the optical head 20.

The optical head 20 includes a laser diode that is driven by a laser drive circuit 25 to emit a laser beam, and an objective lens that focuses a light spot of the laser beam emitted by the laser diode onto the recording track of the optical disc 10 in a focusing direction. It incorporates a two-axis actuator that moves in the tracking direction, a photodetector that detects the return light of the data light reflected by the optical disc 10, and the like. This optical head 20 outputs the detection output from the photodetector as a reproduced RF signal.

Here, the encoder 24 and the laser drive circuit 25 are
The system controller 26 performs control according to the operating mode.

Then, the optical head 20 reads the optical disk IO.
The reproduced RF signal obtained from the data area ADD of the first
The data is supplied from the preamplifier 27 to the decoder 30 via the analog/digital (A/D) conversion circuit 28 of the data reproduction processing system and the digital equalizer 29.
The reproduced digital data D is decoded by 0. Ll
'r is output from the data output terminal 31. In addition,
The A/D conversion circuit 28 and the digital equalizer 29 operate in response to a timing clock supplied from the clock generation circuit 32.

Further, the reproduction RF signal obtained from the servo area ADs of the optical disk 10 by the optical head 20 is transmitted from the second preamplifier 33 to the clock reproduction circuit 34 of the servo information reproduction processing system, the spindle servo circuit 35 and the head surf circuit 36. is supplied to

The clock reproducing circuit 34 detects the clock information pit Q in the reproduced RF signal supplied from the optical head 20. Based on the reproduced output from K, clock reproduction is performed by a so-called PLL to form a clock for synchronizing the entire system and various timing clocks.

Further, the spindle servo circuit 35 is connected to the reproduction RF
The above clock information pit Q in the signal. The rotation angle error of the spindle motor 22 is detected based on the playback output by K, and the motor drive circuit 37 of the spindle motor 22 is controlled so that the optical disc 10 rotates at a constant angular velocity (CAM). Performs spindle servo control.

Further, the head servo circuit 36 performs focus servo control based on the reproduced RF signal of the servo area AR, and also performs focus servo control, and also performs focus servo control based on the reproduced RF signal.
A tracking error is detected based on the reproduced output of wa+'+QWB2, and tracking servo control is performed.

As shown in FIG. 3, this head servo circuit 36 generates a focus error signal S detected by, for example, an astigmatism method. An integrating circuit 41 that integrates y and this integrating circuit 41
The focus servo circuit includes a sample and hold circuit 45 that samples and holds the integral output SINT.

The integration circuit 41 has an operation control switch 43 connected in parallel to its integration capacitor 42, and the operation control switch 43 is controlled to open and close by the control clock CK supplied from the clock regeneration circuit 34. There is. As shown in FIG. 4, this integrating circuit 41 is connected to the operation control switch 43 or the servo area ARS
The focus error signal S, is generated for a scanning period T A RS. . is integrated during the scanning period TAR8 of the servo area AR8.

Further, the sample hold circuit 45 uses a sampling clock CK supplied from the clock regeneration circuit 34.
2, the sampling switch 46 is controlled to open and close, and as shown in FIG. 4, at the end of scanning the servo area AR, at t6, the sampling switch 46 is closed and the integral output S INT from the integrating circuit 41 is held. The sample is held in the capacitor 47.

This focus servo circuit performs focus servo control using the sample hold output 5HoU7 of the sample hold circuit 45 as a focus error signal.

In the optical disc recording apparatus of this embodiment, the clock information pit Q is provided in the servo area AR8 of the optical disc 10. K and a pair of tracking information pits QW
Since B l + Q WB 2 are arranged and formed as described above, the clock information pit Q. , the signal level of the reproduced output for the tracking information pit Q we+ is A sin (ωt+2π/3).
Also, the above tracking information pit Q WB2
The signal level of the playback output is A 5in (ωt-
2π/3) becomes 10B. Therefore, the focus servo circuit shown in FIG. 3 above uses the focus error signal S.
FOE is the scanning period T A R of the above servo area AR.
By integrating the clock information pit Q in the reproduced RF signal. ,&l-racking information pick)
-The sum of each signal level of the reproduced output for QWBI + QVIB2 becomes constant, and the above clock information pit QCK and tracking information pit QWBI + Q
Focus error signal 5 not affected by WB2
You can get HO1l work.

As described above, in the optical disc device of this embodiment, focus servo control, tracking servo control, and clock reproduction can be performed using the overhead of the servo area ARs of the optical disc 10 as 4N channel hits.
Servo area ar required for conventional optical disc 50
The overhead of (5N+1) channel pits of s can be reduced by (N+1) channel pits, and the recording capacity of the data area A Ro can be increased by that amount.

Note that, as in the optical disc shown in FIG. 5, a clock information pit Q for clock reproduction is provided at the innermost circumferential portion of the recording surface, which serves as a lead-in area. P process/3 where K is arranged and formed at the track center position and the track pitch is P7
Tracking point I” QW, +I + Q
By repeatedly providing the servo area ARS in which WB2 is arranged and formed, a focus error can be detected even if the PLL of the clock regeneration circuit is not locked.
It is possible to focus in the lead-in area and also perform clock reproduction at the same time.

In the above embodiment, one clock information pit Q is provided in each servo area. K and two tracking information pits Q
In the optical disc device according to the present invention, the number of tracking pits formed in advance in the servo area AR of the optical disc is not limited to two as in the above embodiment, but can be , a clock information pit Q cK for clock reproduction is provided at the center position of the track, and the track pitch is set to P. Excluding the above track center position at position P a/n (n-1
) may be used as a recording medium, such as an optical disk having a servo area in which tracking information pits are provided.

Here, a pair of tracking information pits QwBIIQW
The moving speed and moving direction of the optical head 20 can be determined from the information on the sum and difference of the signal levels of the reproduction output of B
+ If the cycle at which a tracking error is detected by the playback output of QWB2 is T, then PT /T x 4 (
For example, if T = 12μ5ec PT = 1.5μm, the detection is approximately 0. 03 (m/sec) can be detected. On the other hand, the gray code can only detect the l/rack position in units of one track, approximately 012 (m/5
ec) There is no detection ability below. Therefore, as shown in FIG. 6, n=4 and a clock information pit Q for clock reproduction. K is provided at the center position of the track, and
Tracking information pit Q at 3 locations except for the above track center position at position P/4 where track pitch is Pl
Servo area ARs with WBl+QWB2+QWB3
If an optical disc having the following characteristics is used as a recording medium, the speed detection ability can be improved. In this case as well, the clock information pit Q is generated by integrating and using the focus error signal obtained based on the reproduced output from the servo area. K and tracking information pit Q WBI I
Focus servo control can be performed without being affected by QVB2 + Qll183, and a special mirror area MA for focus error detection is added to the above servo area A.
There is no need to provide it in RI+.

G. Effects of the Invention As described above, in the optical disc device according to the present invention, a clock information pit for clock reproduction is provided in the servo area of the optical disc at the track center position, and a clock information pit is provided at the position of PT/N where the track pitch is PT. Since tracking information pits are provided at (N-1) locations excluding the track center position, the focus error signal obtained by scanning the servo area of the optical disk with the optical head is integrated by the integrating means, and the integrated output is obtained. The signal level of the focus error signal obtained by holding the sample by the sample hold means, that is, the focus error level, becomes constant, and focus servo control can be performed without being affected by the clock information pit and tracking information pit, and focus error detection can be performed. There is no need to provide a special mirror area in the servo area for this purpose. Therefore, it is possible to reduce the overhead of the servo area and increase the recording capacity of the optical disc.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an optical disc device according to the present invention. FIG. 2 is a diagram showing a recording format of an optical disc used in the optical disc device. FIG. 3 is a block diagram showing the configuration of main parts of a focus servo circuit included in the head servo circuit of the optical disc device. FIG. 4 is a waveform diagram for explaining the operation of the focus servo circuit. FIG. 5 is a diagram showing the contents of the servo area of the lead-in portion of the optical disc used in the optical disc device. FIG. 6 is a diagram showing another example of the recording format of the servo area of the optical disc used in the optical disc device according to the present invention. FIG. 7 is a diagram showing a recording format of an optical disc used in a conventional optical disc device. IO...Optical disk 20...Optical head 22...Spindle motor 34...Clock regeneration circuit 35...Spin 1 pulse servo circuit 36...Head servo circuit 41...Integrator circuit 42... Integrating capacitor 43...Operation control switch 45...Sample hold circuit 46...Sampling switch 47...Hold capacitor

Claims (1)

[Claims] Servo areas and data areas are provided alternately along the head scanning direction, and the servo areas and data areas are arranged radially from the center of the disk, and the direction of deviation from the track center and In an optical disk device that uses as a recording medium an optical disk of a sample servo format in which a plurality of tracking information pits for detecting the amount of data and a plurality of clock information pits for clock reproduction are formed in the servo area in advance, A clock information pit is provided at the center position of the track, and the track pitch is set to P_T.
The recording medium is an optical disc having a servo area in which the tracking information pit is provided at (N-1) locations other than the track center position at the position P_T/N, and the optical head scans the recording track of the optical disc. an integrating means for integrating a focus error signal during a scanning period of the servo area, and a sample hold means for sample-holding the integral output of the integrating means at the end of scanning of the servo area, and a sample-hold output by the sample-hold means. An optical disc device characterized in that focus servo control is performed using a focus error signal as a focus error signal.