JPS63225924A - Optical disk and optical disk driving device - Google Patents

Abstract

PURPOSE:To detect a direction in operating access, by setting a distance between a pair on one side of wobble bits and a clock bit larger than a specified grade, and changing the distance repeatedly at every information track. CONSTITUTION:Bits 1-4 and a bit 5 constitute the pairs of wobble bits respectively, and the bit of every pair is deviated a little from the axes of track centers 7-10. The distance between the bits 1-4 and the bit 5 is deviated respectively. The distance between the bit 5 and the clock bit 6 of an information data is kept constant. The bit 6 becomes the clock reference of a recorded information data. The structure of a servo field is formed in cyclic structure of 16 tracks by continuing the same four tracks. Also, it is permitted to set the distances between the wobble bit and the clock bit in more than three grades instead of four grades. In such a way, it is possible to detect the direction in operating the access, and to improve the resolution of track count.

Description

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

[Prior art] Fig. 7 is shown in, for example, SP I E, vol, 695.0p.
tical Mass Data Storag
e2 (1986) Page 12, which shows the track/sector format of a conventional optical disc. 32)
Consists of. , (91) shows the block structure per sector, and one sector 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 32x43=1376 blocks. Figure 8 shows the pit pattern of the servo field, pits (92), (94), and pits (93) (
94) are slightly offset in opposite directions with respect to the axes of the centers (97) and (98) during dragging, respectively, and these pit pairs (this is referred to as a wobble pit (WOBBLED)
The tracking sensor signal can be obtained only from the PIT pair (referred to as PIT pair). This kind of servo method is called sample servo (SAMPLED 5ERVO).
For example, 5PIE, vol, 529, Th1rd I
international conference
0ptical Mass Data St
orage (1985) Page 140 explains the principle of operation of the sample servo, so the explanation is omitted here. Now, in such a conventional optical disc, a tracking sensor signal can be obtained only from a pair of pits in 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, in order to count the amount of track moved during the high speed access operation, in FIG.
, B are arranged alternately. In FIG. 8, the track numbers are as follows: Track number=I+(N-1)X16'where, +/-1.2, 3. ...16, given by servo field structure, N in A; 1.3
,5. ..., N-2,4 in servo field structure B
, 6... servo field structures A and B
In this example, the positions of pits (92) and (93), one of the pits, are shifted in the track direction. When performing an access operation while diagonally crossing a track, by detecting the position of this pit, the amount of track that has been traversed can be determined. This situation will be explained with reference to FIG. In this figure, (71) indicates the track center, and 1
．． There are a large number of them at 5 μm intervals. (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 servo field structure can be recognized at the zero point (74) where the black point (74) indicates the point where the light spot intersects with the servo field. The recognized signal waveform is shown in (99).
indicates B, which means that 16 tracks were counted every time the state of this signal waveform (99) changes.The number of tracks crossed can be counted from the signal waveform (99) during access operation, and the target track can be quickly reached. It will be possible.

[Problems to be Solved by the Invention] The above conventional technology allows tracking force and runt when accessing the optical head at high speed, but as is clear from FIG. However, there is a drawback in that it is not possible to detect whether it is moving toward the outer circumference or toward the inner circumference. As a method for high-speed access 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 not requiring a glass scale, allowing for miniaturization, and reducing mechanical precision. However, when this speed control method is adopted using this conventional disk, the inability to detect direction becomes a fatal flaw. This is because even if the direction is reversed 7 times during speed control, it cannot be detected, so the control loop becomes a positive feedback, which may cause the optical head to run out of control and collide with the stopper on the inner or outer periphery, causing damage. be. In addition, the above conventional technology has 16
Since the servo field structure is different for each book, the servo field structure is different for each book, so the disc rotation speed is 1800 rpm, and the servo field structure is different for each book.
, 5μm)/block period (1/30X1/1376s
It is possible to count tracks up to a high moving speed of ec) = 1.0 m/sec, but it is not possible to count finely for less than 16 tracks, so when the remaining track amount approaches 16, another low-speed track counting technique must be used. vinegar,
This slows down 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 track pitch/block period = 61.9 mm/sec as the maximum detection limit speed.

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 in order to solve the above-mentioned problems, and provides an optical disc and its 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 obtain an optical disk drive device that can control the access speed of an optical head using an optical disk.

[Means for Solving the Problems] The optical disc according to the first invention has a predetermined distance between at least one pit of a pair of wobble pits and a clock pit serving as a reference for information data. The optical disc drive device of the second invention uses the above-mentioned optical disc, Direction detection that detects the distance between at least one of the pair of wobble pits and a clock pit that serves as a reference for information data from the reflected detection signal from the optical disc, and detects the direction of movement from the order of change in that distance. A speed detection circuit is provided to detect the magnitude of the relative speed in the radial direction between the optical disk and the movable part from the reflection detection signal, and the movable part is detected by the output signals of the direction detection circuit and the speed detection circuit. It is characterized by speed control.

[Function] In the first and second inventions, the distance between pits is determined in a predetermined order on the optical disc, so if this disc is used, the direction of movement of the optical 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).
This figure shows the pit pattern of the servo field, (1) and (5), (2) and (5).
), (3) and (5), -(4) and (5) are each one,
The pits of each pair are slightly deviated from the axes of the track center (7), (8), (9), and (10), which is the same as in the conventional technology. .

One of the wobble pits (1), (2), (3)
, (4) are shifted in distance from the other pit (5), respectively.The distance between the pit (5) and the clock pit (6) serving as the clock reference for information data is constant. The clock pit (6) is arranged on the center axis of the track, and serves as a clock reference for recorded information data, and also serves as a reference for generating sampling pulses of the wobble pit. Wobble Pit (1), (2), (3),
Let the timing positions in (4) based on the clock pit (6) be a, b, c, and d, respectively. In Figure 1, where the servo field structure with a pit at timing position a is A, hereafter B, c is C, and d is D, the track number is as follows: Track number = I + (N-1)X4 where I = 1. 2, 3. ．． 4, and for servo field structure A, N; 1.5
,9. ..., when B, N=2.6.10.1...,
When C, N=3.7, 11. ..., when D, N=4.
8.12. ....From this relationship, the servo field structure is AAAABBBBBCCCCDDDDAAAA
..., and the same 4 tracks continue 1
It has a 6-track cyclic structure.

FIG. 2 shows an embodiment of the second invention, (11) is the optical disk of the first invention, (12) is the optical disk (11)
(13) is a photodetector that detects information from the optical disk (11); (14) is a preamplifier connected to the photodetector (13) that converts current into voltage; (15) ) is a speed detection circuit that detects the magnitude of the speed of the optical head (12) in the radial direction with respect to the optical disk (11) from information read from the optical disk (11) and converted into a voltage signal; (16) is a speed detection circuit that converts the voltage signal into (17) is an inverting amplifier circuit; (17) is an inversion amplifier circuit; (17) is an inverting amplifier circuit; (17) is an inverting amplifier circuit;
) is a switch that changes the signal to be transmitted to the next stage depending on the polarity of the output of the direction detection circuit (16), either the output signal of the speed detection circuit (15) or the output signal of the inverting amplifier circuit (17), and (19) is a switch This is a speed control circuit that controls the speed of the optical head (12) using the output of (18) to access a target track. Figure 3 shows the direction detection circuit (16)
In FIG. 3, which shows a specific example of
o) to four sample and hold circuits (21), (22
), (23), and (24). Control signals (26) and (27) for each sample and hold circuit
), (28), and (29) are timing adjustment circuits (2
These are the sampling pulses at timing positions a, b, c, and d created in step 5). The output signal of the sample and hold circuit is sent to comparators (31), (32), (33), (
34), the reference voltage Vr input from the input terminal (35)
ef and their output signals (36),
(37), (38), and (39), the flip-flop (47) has the signal (36) as a set input, and the signal (38) as the set input.
) as the reset input, and its Q output (40) and signal (3
7) is input to the AND gate (49). The Q-output of the flip-flop (47) and the signal (39) are input to an AND gate (50). The flip-flop (48) uses the signal (37) as a set input and the signal (39) as a reset input, and its Q output (41) and signal (38) are input to an AND game (51). Q of flip-flop (48)
- The output and the signal (36) are input to an AND gate (52). Each AND game) - (49), (50), (
51), (52) output signals (42), (43), (4
4) and (45) are input to an OR gate (53) to output a direction detection signal (46).

The operations of the optical disc according to the first invention and the optical disc drive apparatus according to the second invention will be explained below.

Figure 4 shows the reproduced waveform from the pit and the state of sampling. Figure 4 shows the case where servo field structure A is reproduced, and the reproduced waveform from the pit (1) (
54) are shown by solid lines, other virtual pits (2) and (3
), (4) and a virtual playback waveform (55) from there,
This reproduced waveform (54) shows (56) and (57) with broken lines.
) are input from the input terminal (20) in FIG. 3 to the sample and hold circuits (21), (22), (23), and (24), and the sampling pulses ( 58), (62), (63), (64)
sampled. The waveform (59) shows the output waveform of the sample-and-hold circuit (21) which samples the peak value of the waveform (54) with the sampling pulse (58) and holds it thereafter, and the waveforms (65), (66), and (67) respectively Sample hold circuit (22), (23), (2
4) is the output waveform. These output waveforms (59), (
65), (66), and (67) are the comparators (
31), (32), (33), and (34) to set the reference voltage (6
0) and its output signal (36)
, (37), (38), and (39) are (61) in Figure 4,
(68), (69), and (70), that is, when the light spot is moving on the servo field structure A, the output signal (36) becomes "H" level, and the other output signal (
37), (38), and (39) mean that the level is "L", and similarly, servo field structure B
In the case of servo field structure, the output signal (37) is "H" level, and in the case of servo field structure C, the output signal (38) is "H" level.In the case of servo field structure, the output signal (39) is "H" level.
) goes to the "H" level, and the other output signals remain at the "L" level.

Figure 5 shows the servo field structure arranged on the disk surface and how a light spot scans the disk surface.Similar to Figure 9, (71) shows the centers of the tracks arranged at a pitch of 1°5 μm; (72) is the position of the servo field,
(73) is the trajectory of the light spot during high-speed access, and the black dot in (74) is the point where the light spot intersects with the servo field. In Figure 5, the servo field structure is AAAABBBBCCC as shown at the right end of the figure.
It has a repeating structure of CDDDD, and the waveform (7
5), (76), (77), and (78) respectively indicate the waveforms of the output signals (36), (37), (38), and (39) in Fig. 3, and as the light spot moves, The signal that becomes H” level is (36) → (37) → (38) → (39
) can be seen changing in this order. Naturally, when the light spot crosses the track in the order of D→C-B→A, that is, in the opposite direction, the signal at nHn level is (
Needless to say, it changes in the order of 39) → (38) → (37) → (36).

FIG. 6(a) shows the signal waveform when the light spot moves in the same direction as in FIG. 5, and FIG. 6(b) shows the signal waveform when it moves in the opposite direction. (79), (80), (81), (82) are the signals (36), (37), (38), and (39) in Figure 3, respectively.
The waveform of is shown.

(83) is the Q output signal (4) of the flip 20 tube (47).
0) waveform, (84) is the Q of the flip-flop (48)
The waveform of the output signal (41), (85) is the AND circuit (49)
) waveform of the output signal (42), (86) is the AND circuit (
50) The waveform of the output signal (43), (87) is AND
The waveform of the output signal (44) of the circuit (51), (88) is A
This is the waveform of the output signal (45) of the ND circuit (52), and (
89) is the above four signals (42), (43), (44), (
The waveform of the output signal (46) of the direction detection circuit (16) obtained by ORing 45) is shown. In other words, in the case of FIG. 6(a), the output of the direction detection circuit (16) is at "H" level. In the case of the reverse direction as shown in FIG. 2(b), the output is at the "L" level, which indicates that the moving direction of the light spot with respect to the track can be detected.

The operation of the speed detection circuit (15) in FIG. 2 is, for example, based on the duration of the "H" level of each of the signal waveforms (75), (76), (77), and (78) in FIG. Detect. That is, detection speed = 4 x track pitch (1, 5
μm)÷(“H” level period). In a conventional optical disc, the speed can only be detected every 16 tracks, but in the above embodiment, the speed can be detected every 4 tracks, so the dead time of the speed detection circuit can be shortened, and the stability of the speed control system can be increased. Track counting is possible every four tracks, and detailed counting is possible. Since this speed detection circuit essentially detects the magnitude of speed, the above-described direction detection circuit is used in combination to avoid positive feedback in the speed control system. In FIG. 2, the output of the direction detection circuit (16) is set to "H" level when the light spot, that is, the light beam (12) moves toward the outer circumference, and "L" level when it moves toward the inner circumference. When the polarity of the output of the direction detection circuit (16) is "H", the switch (
18) is switched to the speed detection circuit (15) side, and when it is L'', it is switched to the inverting amplifier circuit (17) side, so that the analog input signal of the speed control circuit (19) is, for example, in the outer circumferential direction when positive, and when negative In this way, even if the direction is reversed during the access operation, the speed control system will not enter positive feedback and stable control will be achieved. It becomes possible.

Note that in the optical disc of the above embodiment of the first invention, the distance between the other pit (5) of the pair of wobble pits and the clock pit (6>) is fixed, but this distance also has one or more information tracks. 1 (b).
In this figure showing another embodiment of the pit pattern structure of the optical disk according to the invention, (1) and (5), (2) and (
5), (3) and (5), and (4) and (5) are each a pair of wobble pits, and (6) is a clock pit, as in the above embodiment. However, in this figure, one of the wobble pits (1), (2), (3), (4)
) and the clock pit (6) are not only different, but also the distance between the other pit (5) of the wobble pit and the clock pit (6) is different. Pit (1), (
The respective timing positions of 2), (3), and (4) are a, b, c, and d, which are the same as in the previous embodiment, and the timing position of the pit (5) can be shifted in three steps, e, f, and H. be.

By independently shifting the positions of the two pits in this way, a large amount of information can be stored in a certain pit space. The servo field structure has eight sets A-H, and the timing positions where wobble pits exist in A are a and g, below, in B, a and f, in C, a and e, and in D, b and e, for E, b and f, for F, b and g, for G, C and g, and for H, d and g. The track number is given by: Track number=I+(N-1)X2 where I=1.2, and when A, N=1.9. ..., N when B
=2.10. ..., when C, N=3.11. ...,
When D, N=4.12. ..., when E, N=5.13
,..., when F, N=6.14. ...-'G when N=7.15. ..., N±8 when H. ．． 16.・・・
・Given by That is, the servo field structure is AAB
It has a repeating configuration of 16 tracks of BCCDDEEFFGGHH. The combination of the two timing positions where wobble pits exist is servo field structure A.
Since it is unique in all of ~H, it is uniquely determined which servo field structure the light spot is on when it passes through the servo field. This means that the moving direction of the light spot with respect to the track can be detected, as is clear from the explanation of the operation of the above embodiment. In this embodiment, although the maximum detection speed is the same as in the previous embodiment because the repeating unit is 16 tracks, the dead time of the speed detection circuit is longer than in the previous embodiment because the speed can be detected every two tracks. It is further shortened by half and the stability of the speed control system is further improved. Furthermore, the resolution of track counting is also improved twice as compared to the previous embodiment.

Also, one pit (1) of a pair of wobble pits, (
The distance between the pair of wobble pits and the 20 pits may be changed while keeping the distances between pits 2), (3), and (4) and the other pit (5) constant.

Since the distance between the wobble pits is constant, the interference between the pits is constant and a stable tracking sensor signal can be obtained.

Further, in the optical disc of the first embodiment of the first invention, the distance between the wobble pit and the clock pit is set in four stages.
The distance is repeatedly changed for each information track of the book, but as long as there are three or more steps, direction detection is possible, so the distance can be any number of steps, and the number of information tracks with the same distance can be one or more. It goes without saying that the smaller the number of tracks, the less time is wasted in speed detection, and the more detailed track counting becomes possible.

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 can detect the direction during an access operation and can improve the resolution of track counting.

Further, the optical disk drive device of the second invention is capable of performing access operations using the optical disk of the first invention by detecting the speed and direction from the information track and controlling the speed, which has the effect of miniaturizing the device.

[Brief explanation of drawings]

FIG. 1(a) is a pattern configuration diagram showing a first embodiment of the pit pattern of the optical disk of the first invention, FIG. 1(b)
2 is a pattern configuration diagram showing a second embodiment of the pit pattern of the optical disc of the first invention, FIG. 2 is a block diagram showing an embodiment of the optical disc drive device of the second invention, and FIG. FIG. 4 is an explanatory diagram showing the reproduced waveform and sampling operation of these inventions, and FIG. 5 is a servo field structure of the optical disk of the first invention. FIG. 6 is a signal waveform diagram explaining these inventions, the 71st pattern configuration diagram, and 9th
The figure is an explanatory diagram showing the servo field structure of a conventional optical disc and how a light spot scans the disc surface. In the figure, (1), (2), (3), (4), (5)
is a pit, (6) is a clock pit, (11) is an optical disk, (12) is an optical head, (13) is a photodetector, (1
4) is a preamplifier, (15) is a speed detection circuit, (16)
is a direction detection circuit, (17) is an inverting amplifier circuit, (18) is a switch, and (19) is a speed control circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (5)

[Claims] (1) The distance between at least one pit of a pair of wobble pits and a clock pit, which is a reference pit for information data, is a distance of three predetermined levels or more,
An optical disc characterized in that the distance of one or more information tracks is repeatedly changed in a predetermined order. (2) The distance between at least one pit of a pair of wobble pits and the clock pit, which is the reference pit for information data, is set to four levels, and the distance is repeatedly changed for each of the four information tracks. An optical disc according to claim 1, characterized in that: (3) The combination of distances between each pit of the pair of wobble pits and the clock pit, which is the reference pit of information data, is set to three or more predetermined levels,
An optical disc according to claim 1, characterized in that the distance of one or more information tracks is repeatedly changed in a predetermined order. (4) There are eight combinations of distances between each of the pairs of wobble pits and the clock pit, which is the reference pit for information data, and the distances are repeatedly changed in a predetermined order for each two information tracks. The optical disc according to claim 3, characterized in that: (5) The distance between at least one pit of the pair of wobble pits and the clock pit, which is the reference pit for information data, is a distance of three predetermined levels or more,
A movable part of an optical head that is movable in the radial direction of an optical disk whose distance is repeatedly changed in a predetermined order for each of one or more information tracks, and a photoelectric conversion device that detects the amount of light reflected from the optical disk and converts it into an electrical signal. , detecting the distance between at least one of the pair of wobble pits and a clock pit, which is a reference pit for information data, from the output signal of the photoelectric conversion device, and detecting the moving direction from the order of change in the distance. a direction detection circuit; a speed detection circuit for detecting the magnitude of the relative velocity in the radial direction between the optical disk and the movable part from the output signal of the photoelectric conversion device;
An optical disk drive device characterized in that the speed of the movable part is controlled by output signals of the direction detection circuit and the speed detection circuit.