JPH01243240A - Optical disk and optical disk driving device - Google Patents

Abstract

PURPOSE:To detect the travel direction of a head in performing an access operation, to prevent the runaway of the head from occurring, and to improve the resolution of track count by deciding a pit pattern in sequence decided in advance on an optical disk. CONSTITUTION:In the optical disk on which a pair of wobble pits and a clock pit are preformatted at a constant interval in a track direction, the address pit patter of each track is constituted of a binary code Dn {(n): relative track number, Dn: A(n, 1)-A(n, k)} of K digits, and it is set as a cyclic code at N cycles (N>=8). Also, it is set as the code in which two or more digits of logic '1' exist in each Dn in a condition where three or more digits of '0' exist in that cycle. A device to drive the optical disk 11 constituted in such way consists of an optical head 12, an optical detector 13, a pre-amplifier 14, a speed detector 15, a direction detector 16, an inversion amplifier circuit 17, a velocity control circuit 19, and a wobble pit pattern detector 20, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical disc and an optical disc drive device,
In particular, the present invention relates to a servo preformat method in which an optical disc is pre-engraved and an optical disc drive device suitable for the preformat.

[Prior art] Figure 8 shows, for example, 5PIE, vol, 695.0pti.
cal Mass Data Storage
2 (1986) page 12 is a diagram showing the track/sector format of a conventional optical disk. In the figure, (90) shows the sector structure per track-round, and one track consists of 32 sectors (#0 to #32). (91) shows the block structure per sector, and sector (2) consists of 43 blocks (B1 to B43). Each block consists of a 2-byte servo field followed by a 16-byte data field, and one track is divided into 32×43=1376 blocks. FIG. 8 shows the pit pattern of the servo field. Pit (92), (94), and Pit (9
3) (94) are track centers (97) and (98), respectively.
) with respect to the axis of the pits, and these pit pairs (we call them wobble pits (WOB B
The tracking sensor signal can be obtained only from the pair L E D P I T'). This kind of servo system is used as a sample servo (SAMPLED 5E).
RVO) 1, for example, SP, IESvo 1.
529, Th1rd International
Conference on 0ptical
Mass Dala Storage (1985
) The operating principle of the sample servo is explained in 140, so it will be omitted here. Now,
In such a conventional optical disc, a tracking sensor signal can be obtained only from a pair of pits within a servo field, so a guide groove for tracking is not required. Therefore, in order to access a target track from the current track at high speed, the servo field structures A and B are arranged alternately every 16 tracks in FIG. 9 so that the amount of track moved during the high-speed access operation can be counted. ing. In Figure 9, the track numbers are ',
Track number -1+(N-1)Xl, I=1.2. ．． 3. ...given in 16,
In servo field structure A, N-1°3.5. ...,
In servo field structure B, N=2. ．． 4,6.・
It is... In servo field structures A and B, the positions of pits (92) and (93), one of the pit pairs, are shifted in the track direction. When an access operation is performed while diagonally crossing a track, the amount of track traversed can be determined by detecting the position of this pit. This situation will be explained with reference to FIG.

, In this figure, (71) indicates the center of the track, and there are many tracks at intervals of 1.5 μm. (72) indicates the position of the servo field, and the servo field structure is A and B for every 16 tracks as shown at the right end of the figure. (73) is the trajectory of the light spot during high-speed access. The black dot (74) indicates the point where the light spot intersects with the servo field. Point (7
The servo field structure can be recognized in 4). The recognized signal waveform is shown in (99). "■]" level indicates servo field structure A, and 'L' indicates B. This means that 16 tracks are counted every time the state of this signal waveform (99) changes. ), the number of tracks crossed can be counted, and the target track can be quickly reached.

[Problems to be Solved by the Invention] The above conventional technology allows track counting when accessing the optical head at high speed, but as is clear from FIG. There is a drawback that it is not possible to detect the direction of movement, whether it is moving toward the inner circumference or toward the inner circumference. As a method for high-speed operation, there is a method in which the speed is controlled by extracting the speed detection signal during access from the disk.This speed control method is faster than the conventional method, which uses an external glass scale to control the speed. This has the advantage of eliminating the need for a glass scale, allowing for miniaturization, and reducing mechanical precision. However, when this speed control method is adopted using a conventional optical disk, the inability to detect direction is a fatal flaw. This is because even if the direction is reversed during speed control, it cannot be detected, so the control loop becomes a positive feedback,
The optical head may run out of control and collide with a stopper on the inner or outer periphery and be destroyed. In addition, in the prior art described in Section 2, the →J-Bofield structure is changed every 16 discs, so when the disc rotates at 1800 rpm, 16×! - Rack pitch (5 μm)/block period (1/30/X1./1.
Although it is possible to count tracks up to a high moving speed of 376 sec) = 1.0 m/sec, detailed counting of less than 16 tracks is not possible.

Therefore, when the number of remaining trunks approaches 16, another low-speed track counting technique must be used, which reduces the speed and becomes a major hindrance to shortening the access time. The low-speed track counting technique referred to herein is a method of counting from the number of track crossings of the tracking sensor signal of the sample servo, with a detection limit maximum speed of 1-rack pitch/block period-6.9 mm/sec. Furthermore, when controlling the speed by extracting the speed detection signal being accessed from the disk, the speed signal can only be detected after moving 16 tracks, which increases the dead time of the speed detector and makes the speed control system unstable. As the speed increases, broadband high-speed speed control becomes impossible. The present invention was made to solve the above-mentioned problems, and provides an optical disc and optical disc that can detect the direction and increase the counting resolution without reducing the maximum possible track counting speed. The object of the present invention is to provide an optical disk drive device that can control the access speed of an optical head using the following methods.

[Means for Solving the Problems] The optical disc according to the first invention has a pattern arrangement in which the wobble bit pattern is changed for each rack and speed control and direction detection during access can be performed more precisely. This is what we provide. Its characteristics are that when each wobble pit pattern is coded Dn, there are two digits "1" in the code Dn, and the digit "■
The first feature is that the number of digits "O" between "0" is 3 or more, and in the relationship between consecutive Dn and Dn-1-1, the position of either digit "1' is always the same. , a second feature in which the positions of other digits "1" differ by one bit, and a third feature in which the code Dn is a cyclic code every N tracks.

Therefore, as will be described later, the detection ability of the wobble bit signal is high even during tracking and access. A/D the playback signal of the wobble pit section from the signal
The relative track address change is decoded from this detected wobble bit pattern by converting it, setting its upper two sample values as logic "1", and using a highly capable detector capable of maximum likelihood decoding. A direction detection circuit is provided for detecting the moving direction from the order of The present invention is characterized in that the speed of the movable part is controlled by the output signal of the delivery detection circuit.

[Function] In the first and second inventions, the pit patterns are determined in a predetermined order on the optical disc, so if this disc is used, the direction of movement of the head can be detected during the access operation of the optical head. This makes it possible to prevent the head from running out of control and to increase the resolution of track counting.

[Example] A first example of the optical disc of the first invention is shown in FIG. 1(a).
Shown below. The figure shows the bits and patterns of the servo field. In the figure, (1) and (2) each constitute a pair of wobble pits, and the bits of each pair are slightly shifted from the center axis of the track, which is the same as in the prior art. The wobble pit pattern in each track is {A (n, 1), 'A (n, 2)-
・Δ(n.

! O) It can be expressed by a code Dn (n is 1 to 18) indicated by l, and the digit position of the wobble pit of each Dn is a logical
1".The recording and reproduction clock uses the detection signal of the clock pit (3) that occurs at a constant cycle as a comparison signal,
Creating a clock synchronized with each digit using a PLL (Phase Locked Loop) circuit is the same as in the conventional method. In the figure, the code Dn is
The code changes for each track, and is a cyclic code every 18 tracks. Moreover, each Dn is A (n.

1) ~A (n, 5) and A (n, 6) ~A (
n.

10) There is one "1" among the digits, and there are three or more "0" digits between them.

Also, as a feature of Dn+1 and Dn-1 adjacent to Dn, one "1" digit is in the same position, and the other "1" digits are in the same position.
The 1" digit is at a position shifted by 1 bit. FIG. The pattern has one “1”. In this case, the number of turns is 28. Figure 1 (c)
is another example in which the number of constituent digits is 12. FIG. 2 shows an embodiment of the second invention. (11) is the optical disc of the first invention, (12) is the optical disc (11
), (13) is a photodetector that detects information from optical disk (11), (14)
is a preamplifier that is connected to a photodetector (13) and converts current into voltage; (20) is a wobble pit pattern detector; and (20) is a wobble pit pattern detector. ) for detecting the magnitude of the speed in the radial direction relative to the optical disk (11), and (16) similarly detects the moving direction of the optical head (12) in the radial direction (inner circumference) relative to the optical disk (11) based on the relative track address information. direction or outer circumferential direction), (17) is an inverting amplifier circuit, (18
) is a switch which switches the signal to be transmitted to the next stage between the output signal of the speed detection circuit (15) or the output signal of the inverting amplifier circuit (17) depending on the polarity of the output of the direction detection circuit (16). ) is a speed control circuit that controls the speed of the optical head (12) according to the output of the switch (18) to access a target track.

Referring to FIGS. 3, 4, and 5, the construction method of the code Dn, which is the basis of the present invention, and its characteristics will be explained. ,
FIG. 3 is a diagram of wobble pits and their reproduced waveforms. FIG. 3(a) shows a wobble bit, the pattern of which has the characteristics of the code of the present invention. A necessary condition for wobble pits is that when the optical head is tracking a regular track center, each wobble pit position is recognized by its track sector number, as in the conventional example shown in Figure 8, and the track sector number is recognized. The absolute address of is known. Therefore, it is possible to know the uniquely arranged wobble pattern with respect to the absolute track address, and no problem occurs even if the wobble pit pattern is different for each track. Also, even if you do not know the absolute address of the track, you can read the playback signal of the wobble pit area at each digit position.

Tracking error information can be obtained by converting into a digital value using an A/D converter and comparing the values of the top two samples. Track n in Figure 3(a)
The reproduced signal of track n+1 becomes (b), and the reproduced signal of track n+1 becomes (d, ). Tracking servo is track n
When reproducing, the A/D converter determines the signal amplitude at each digit position of A(n+2) and A(n,?), and the tracking servo system is controlled so that the amplitude values of both signals are equal. Bye. On the other hand, during access, the optical head performs (40)+' (50), (60
), their trajectories pass differently. The optical head (6
0), the reproduced signal will be as shown in (C).In this case as well, it is necessary to know the digit position of "■" in each Dn pattern.When detecting from the reproduced signal,
In the code arrangement using the code of the present invention, the reproduced signal is A/D converted at each digit position based on the characteristics of adjacent codes, and two samples are determined to be "1" based on the maximum value. With this method, in the case of the waveform (C), the determination code is determined to be either the code Dn of track n, the code D of track n-1-1, or n+1, and the change in the playback signal level etc. The detection capability can be increased without depending on the On the other hand, when the number of digits "1" and "■" (referred to as run length) of each code is R, the condition of R>-3 is a value that takes into account the code amount interference, and the code amount interference is tolerable. If possible, R may be made smaller.

Next, let the number of digits of the code Dn be K, and consider the cyclic number N when the above-mentioned R is arbitrarily selected. FIG. 4 shows an explanatory diagram thereof, and FIG. 5 shows an example thereof. Figure 4 (
a) code Dn in A (n.

Suppose that i) and A(n, j) have the logic "■".

At this time, i is 1 to (K-R) as shown in (b).

Consider a lattice diagram where j is (r +1) ~. Just K
-R)>2. Areas other than the shaded areas on this grid are patterns that satisfy run length>=R.

The method for generating the code Dn of the present invention is a method in which all routes starting from an arbitrary lattice, moving to a lattice shifted in the i or j direction, and finally returning to the initial lattice position are allowed. However, passing through the same grid twice is prohibited. When K and R are given, the maximum N is given by the largest integer value that satisfies the following formula.

However, K-R>2.

On the other hand, consider a code in which Dn is divided equally into first-half digits and second-half digits, and one "1" exists in each equally divided code. When this code is used, the ability to detect disc defects and the like is further increased.

FIG. 5 shows possible values of N. Figures 5(a) and (
b) is the case where R is 3 and 4, (c) and (d)
is the value when the condition that "1" is provided in the first half and the second half of the first period Dn is applied. On the other hand, consider the logic for determining the relative trunk number n after the pattern Dn is detected. The decoding method is basically possible by using a conversion ROM, but if the input address of the ROM is large or if a gate array IC or the like is used, the hardware increases and is not practical. As an example of the present invention, consider the code shown in FIG. 1(b) and find the track number n from this code string. In this case, Dn is Dn-{A (n, 1), A (n, 2), ~A (
n.

11), A(mouth, 12)1 is given. Dn, Dnl-{A (n, 1), A (n, 2), -Δ(n
, 6)) DN2= (Δ(n, 7), A (n, 8), ~A
(n, 12)). The digit "1" address position in each code is in the positions 0 to 5, and the address value is
It is expressed as a 3-bit binary number below.

Vl−yO+2*y I+4*y2 V 2 = Z O+2* z l +4 * z 2
In addition, the following parameters are defined.

PO=yO P 1=yO*y 1*y2 P3=yO*y 1*y2 p4=1τ*y 1*y2 P5-:yO*y-ding*y2 P　6=　z　O*Ding*Z2 V1=5-Vl v2'=5-v2 Address number n is expressed by the following formula.

n=P5* (Vl+PO*V2+PC1*V20P1
*5+P2*8+P3*11+P4*14+P5*]
3) +'P6*(13+V2"+V1) FIG. 6 shows a specific example of wobble bit pattern detection! (20). FIG. 7 is an explanatory diagram of its waveform. In FIG. The reproduced signal (c) that has been reproduced and converted into a voltage signal is input to the input terminal (36), and Δ/D
The converter (21) l- converts it into a digital value at the sampling position of the input clock (d). (d)
is a signal generated by the PLL circuit from the above-mentioned Kuronokubi yh. The digital signal (37) is input to the first and second half code pattern detectors (34) and (35). Detection frequency dividing gates (e) and (f) are input to terminals (30) and (32). Here, the code pattern detector (34) in the first half will be explained. Now, suppose that the digital value (37) of the input signal takes the value (g), then the signal passed through the AND gate (22) (
The value of 38) is (h). Next, the signals (38) and (39) are sent to the comparator (2) via the latch circuit (23).
4) Enter. When the value of the signal (38) becomes greater than (39), the output of the humpator becomes "H", the value is latched, and the process moves to (39). In this example, the signal (39
) is (i). The one-shot multi (25) is driven by the Usochi signal at this time, and its output (
40), (j)'s)<Rus occurs. This pulse causes the counter (26) to count 4 digits of the pattern.
(In this case, it is 5 bits and takes a value of 0 to 4, so it is 4.) When the pulse is not generated,
The value is subtracted by the clock (d). on the other hand,
The section where the gate (e) is "L" is configured to be cleared, and when the separation gate (e) ends, the output signal (41) of the counter is latched by the latch circuit (27).
The value of the output signal (42) becomes 3 as shown in (1), and 2
The signal is output to the output terminal (31) as a 3-bit hex code signal. Similarly, the code indicating the bit position in the second half is also the output terminal (
33) as the value 2 and is output at the timing (m). By processing this signal output in the logic circuit of the algorithm for calculating the track number mentioned above, a relative track address is created in binary code. The speed detector (15) and direction detection circuit (16) of FIG. 2 utilize this change in relative track address during access to set their values. For example, the time between servo sectors is known because the rotation speed is constant, and the number of tracks moved can be determined from the difference in relative track address values at that time, and the distance traveled can be determined. can. Speed can be determined from time and distance. Also, the direction can be known from changes in the value of the relative track address.

-19= These determinations can be easily processed by a microcomputer. In the configuration of FIG. 2, a light spot,
That is, when the optical head (12) moves toward the outer circumference, the output of the direction detection circuit (16) is set to "H" level, and when it moves toward the inner circumference, the output of the direction detection circuit (16) is set to "L" level. When the polarity is "H", the switch (18) is placed on the speed detection circuit (15) side, and when the polarity is "L", the switch (18) is placed on the side of the inverting amplifier circuit (17).
) side, the speed control circuit (19)
For example, the analog input signal of is a signal having direction information such that when positive, the movement is toward the outer circumference, and when negative, the movement is toward the inner circumference. In this way, even if the direction is reversed during the access operation,
The speed control system does not undergo positive feedback, allowing stable control. As explained above, the use of the wobble bit pattern of the present invention provides the following advantages.

(1) The ability to detect detection patterns during access can be increased.

(2) The code amount interference of the detection pattern is small.

(3) Track number decoding hardware can be easily constructed from the detection pattern.

(4) Direction detection and speed detection capabilities can be performed for each sample byte, allowing more precise control.

(5) By using 12 bits and 2 bits of wobble bit code, 28 to 32 relative track addresses can be created, making it possible to cope with both high-speed and low-speed seeks.

Further, in the above embodiment, the case where the entire optical head is driven for access has been explained, but it goes without saying that the present invention can also be applied to the case where a part of the optical head is driven for access in the case of a separate type optical head. Further, the optical disk may be a write-once type, an erasable type including a magneto-optical disk, or a read-only type including a compact disk.

[Effects of the Invention] As described above, the optical disc of the first invention is capable of detecting the direction during an access operation and can improve the resolution of track counting.

Furthermore, the optical disk drive device of the second invention is capable of performing an access operation of controlling the speed by detecting the speed and direction from the information track using the optical disk of the first invention, and has the effect of downsizing the device.

[Brief explanation of the drawing]

FIG. 1(a) is a pattern configuration diagram showing a first embodiment of the bit pattern of the optical disc of the first invention, FIG. 1(b)
FIG. 1(c) is a bit pattern code configuration diagram showing second and third embodiments of the bit pattern of the optical disc of the first invention, and FIG. 2 is an embodiment of the optical disc drive device of the second invention. A block diagram showing an example, FIG. 3 is an example of a bit pattern and a reproduced signal, FIG. 4 is an explanatory diagram of the code structure of the bit pattern of the optical disc of the present invention, and FIG. 5 is the number of codes of the bit pattern of the optical disc of the present invention. , FIG. 6 is a circuit diagram showing a specific embodiment of the wobble bit pattern detector of FIG. 2, FIG. 7 is a waveform diagram explaining the operation of FIG. 6, and FIG. 8 is a diagram of tracks and sectors of a conventional optical disc. Figure 9 is an explanatory diagram showing the bit pattern configuration of a conventional optical disc, and Figure 10 is an explanatory diagram showing the servo field structure of a conventional optical disc and how a light spot scans over the disc diagram. be. In the figure, (1) and (2) are bits (3) and clock bits (11) are optical disks,
(12) is an optical head, (13) is a photodetector, (14) is a preamplifier, (15) is a speed detector, (16) is a direction detection circuit, (17) is an inverting amplifier circuit, and (18) is a switch. (19) is a speed control circuit, (20) is a wobble bit pattern detector, (21) is an A/D converter, (22)
is an AND gate, (23) is a latch circuit, (24) is a comparator, (25) is a one-shot multi, (26)
is a counter, and (27) is a latch circuit (34). (35) is a code pattern detector. Note that the same reference numerals in the figures indicate the same or corresponding parts. Sai + town, f'rE50) (d) 〆\ 〆\ Procedural amendment (method) 1. Indication of case: Japanese Patent Application No. 63-70307 2, title of invention: Optical disk and optical disk drive device 3
, Relationship with the case of the person making the amendment Patent Applicant Address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Moriya Shiki 4, Agent 5, Date of amendment order ( 6. Drawings subject to correction 7. Contents of correction (1) Figure 1 (a), Figure 7, Figure 8, and Figure 10 will be revised as shown in the attached sheet. 8. List of attached documents (1) Revised drawings (Fig. 1 (a), Fig. 7, Fig. 8. Fig. 10) 1 copy or more

Claims (2)

[Claims] (1) In an optical disc on which a pair of wobble pits and clock pits are preformatted at regular intervals in the track direction, the wobble pit pattern of each track is
It consists of a binary code Dn of digits (where n is the relative track number and Dn is {A(n, 1), A(n, 2)
, . . A(n, k)}. ) The code Dn is a cyclic code with N periods (N is an integer of 8 or more), and each Dn has a logic "1" digit and three or more "0" digits in between. It is assumed that two codes exist under the condition that Also, the symbols Dn and Dn+
1, the code obtained by adding mod 2 is also a code in which there are two logical "1" digits. (2) In an optical disk drive device for recording and reproducing an optical disk having a wobble pit pattern in which there are two logical "1" digits and a code Dn consisting of K digits is cyclically repeated every N tracks, A movable part of an optical head that is movable in the radial direction of the optical disk, a photoelectric conversion device that detects the amount of reflected light from the optical disk and converts it into an electrical signal, and a code Dn of the wobble pit portion that is detected from the output signal of the photoelectric conversion device. , the output signal is A
/D conversion, and a wobble pit pattern detector that sets two sample positions of the upper signal level in the wobble pit portion to logic "1", and direction detection that detects the moving direction from the order of change of the detected wobble pit pattern. a speed detection circuit for detecting the magnitude of the relative speed in the radial direction between the optical disk and the movable part from the output signal of the photoelectric conversion device, and the movable part An optical disk drive device characterized by controlling the speed of