JPH02199636A - Optical disk and optical disk driver - Google Patents

Abstract

PURPOSE:To detect the direction even during high speed accessing and to improve the resolution of track count and track density by shifting address information of a track one by one for M-track each and recording the information with an address pit of a pattern changing repetitively at a period of N blocks. CONSTITUTION:A pattern of address pits 4,5 formed on a track is selected to be K bits having two significant bits with nonsignificant bits inbetween. Then M tracks are used as one block, the information is changed for each block for a period of N blocks and a pattern between the 1st block and the N-th block between adjacent blocks and periods is recorded while one of the 2 significant bits is being shifted by one. That is, the significant bit between the 1st and the last blocks between adjacent blocks and periods is only deviated by one bit. Thus, the accessing is fast, a change in the pattern is less and the direction of the track is surely detected, and the track count resolution is improved and also the track density is improved.

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 an optical disc and an optical denosk drive device having pre-engraved address pits for recording track addresses.

[Conventional technology]

Figure 8 shows, for example, 5PII! , vol, 695.0pti
cal l'1assData Storage 2(
1986) is a diagram showing the track/sector format of a conventional optical disc shown in page 12. In the figure, reference numeral 90 indicates the sector structure per track-period, and one track consists of 32 sectors (110 to 1131). 91 indicates the block structure per sector, and the sector (1) consists of 43 blocks (81-843). Each block consists of a 2-byte servo field followed by <16
Consists of a data field of bytes,! It is divided into 32 x 43 = 1376 blocks per track. FIG. 9 shows the bit pattern of the servo field. Bits 92.94 and 93.94 are each slightly offset in opposite directions with respect to the axis of track center 97.98, and these bit pairs (this is called a wobble bit (WOBBLE!DPIT) pair) )
The tracking sensor signal can be obtained from This kind of servo system is called sample servo (SAMPLI!D).
5ERVO) method, for example, Sr1[1Svo1
．． 529, Th1rd International C
0ptical mass
Data Storage (1985) page14
0 explains the operating principle of the sample servo,
It is omitted here. Now, in such a conventional optical disc, a tracking sensor signal can be obtained from a pair of bits in a servo field, so a guide groove for tracking is not required. Therefore, in order to quickly access a certain target track from the current track,
In order to be able to count the amount of track moved during high-speed access operation, in FIG. 9, servo field structures A and B are arranged alternately every 16 tracks. In FIG. 9, the track numbers are as follows: Track number=t+ (N-1)Xl, I=l,
2, 3. ...16, and in servo field structure A, N=1°3.
5. ..., in servo field structure B, N=2°4.
6. It is... Servo field structure A and B
In this example, the positions of bits 92 and 93, one of the bits in the pair, 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 bit. This situation will be explained using Fig. 1θ. In this figure, 71 indicates the center of the track, and there are a large number of tracks at intervals of 1.5 μm. Reference numeral 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 a trajectory of a light spot during high-speed access.

The black dot 74 indicates the point where the light spot intersects the servo field. At point 74 the servo field structure can be recognized. The recognized signal waveform is shown in 99. "H# level indicates servo field structure A, and "L" indicates B.

This means that 16 tracks were counted every time the state of the signal waveform 99 changed, and the signal waveform 99 during the access operation was counted.
The number of tracks crossed can be counted from the number of tracks crossed, and the target track can be quickly reached.

[Problem to be solved by the invention]

The above conventional technology allows track counting when the optical head is accessed at high speed, but as is clear from FIG. It has the disadvantage that it is not possible to detect the direction in which it is moving.

On the other hand, as a method for accessing the optical head at high speed,
There is a method that controls the speed by extracting the speed detection signal being accessed from the disk.This speed control method does not require a glass scale and is more compact than the conventional method, which uses an external glass scale to control the speed. It has the advantage of being able to reduce machine precision as well as reducing machine 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 positive feedback, which may cause the optical head to run out of control and collide with a stopper on the inner or outer periphery and be destroyed.

In addition, since the above conventional technology changes the servo field structure every 16 discs, when the disc rotates at 1800 rpm,
16 x track pitch (1.5 μm)/block period (
1/30 x 1/1376sec) = 1.0m/
It is possible to count tracks up to a high speed of 1.2 seconds, but on the other hand, detailed counting of less than 16 tracks is not possible. Therefore, when the number of remaining tracks 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 track sensor signal of the sample servo, with a maximum detection limit speed of track pitch/block period -61° 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.

Furthermore, since the wobble bit position changes depending on the track, the following problem occurs. That is, when the track pitch is reduced in order to increase the capacity of an optical disc, the reproduction signals of wobble bits 92 and 94 in FIG. 9 are affected by the wobble pits of the adjacent tracks. However, the wobble pits 93 and 94 are in different positions and have different effects on adjacent tracks. For this reason, the reproduced signal amplitudes of the wobble pits 92 and 94 are different and normal tracking cannot be performed.

This invention was made to solve the above-mentioned problems, and it is possible to detect the direction even during high-speed access operation, and to increase the counting resolution without reducing the maximum possible track counting speed. An object of the present invention is to obtain an optical disk whose performance can be increased even when the track density is improved, and an optical disk drive device which can control the access speed of an optical head using the optical disk.

[Means to solve the problem]

The optical disc according to the first invention has a pattern of address pits formed in a track as a bit pattern having two significant bits sandwiching one or more unintentional bits, and M tracks as one block. The pattern is changed for each block and repeated in a cycle of N blocks, and the pattern between adjacent blocks and between the 1st block and the Nth block of the cycle is changed by changing one of the two significant bits to 1 bit. It is shifted and recorded. An optical disc drive device according to a second aspect of the invention is capable of moving in the radial direction of the optical disc according to claim 1, and has a speed of an optical head that irradiates the optical disc with light, detects the light from the optical disc, and converts it into an electrical signal. The pattern of the address pits is controlled by the moving direction detected from the order of change and the relative speed detected by the electric signal.

[Effect]

In the optical disc of the present invention, track address information is recorded not with wobble pits but with address pits in a pattern that is shifted by 1 every M tracks and changes repeatedly at a cycle of N blocks, and when this disc is played back, Since the pattern of address pits is determined in a predetermined order, the moving direction and speed of the head can be detected during the access operation of the optical head, preventing runaway of the head and increasing the resolution of track counting. It is possible to improve the track density.

〔Example〕

A first embodiment of the optical disc of the first invention is shown in FIG. The figure shows the bit pattern 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. 3 is the clock bit, wobble pit 1
It is formed at the center of the track between and 2. 4 and 5
is an address pit. The address pit pattern in each track is (A (n+s, 1),
A (ns+, 2) ”A (nm, 6) )
It can be expressed by the code D nm (n is 1 to 8, m is 1, 2), and the digit position of the address pit of each D0 indicates logic "1". The recording and reproduction clock is the same as the conventional method in that the detection signal of clock pit 3 that occurs at a constant cycle is used as a comparison signal, and a clock synchronized with each digit is created by a PLL (Phase I, locked loop) circuit. . In the same figure, the code D0 changes every M tracks (M is 2) and NXM (N is 8
) Each track has a cyclic code.

Also, each code D0, A (n, 1) ~A
(n+w, 3) and A (nm, 4) ~
There is one "1" among the digits of A (rv, 6), and there are one or more "0" digits between them. Also D7. 1. and D-, 1. and the code DI at the beginning of each period.
The characteristic of + and the last sign mz is that one "1' digit is in the same position, and the other "1m digit is 1
It is in a bit-shifted position. FIG. 2 shows an example in which the order of change in address pits is different.

Next, a drive device for an optical disc formatted as described above will be explained. FIG. 3 is a block diagram showing an embodiment of the optical disc drive device of the second invention. In the figure, 11 is an optical disc of the first invention, and optical disc 1
On the lower surface of the optical disk 11, a disk 12 is movable in the radial direction of the optical disk 11 and faces the light beam for recording and reproducing information. I3 is a photodetector that detects information from the optical disc 11, and the detected information is given to a preamplifier 14 connected to the photodetector 13 and converting current into voltage. The output signal of the preamplifier 14 is given to an address pit pattern detector 20, which detects the magnitude of the speed of the optical head 12 in the radial direction with respect to the optical disk 11 from the relative trunk address information detected by the pattern detector 20. The signal is supplied to the speed detector 15 and a direction detection circuit 16 that similarly detects the direction of radial movement of the optical head 12 relative to the optical disk 11 (inner circumferential direction or outer circumferential direction) from the relative track address information. Its output signal is
Direction detection circuit 1 via inverting amplifier circuit 17 and as it is
Depending on the polarity of the output of 6, it is applied to a switch 18 which switches the signal to be transmitted to the next stage between the output signal of the speed detector 15 or the output signal via the inverting amplifier circuit 17.

A speed control circuit 19 controls the speed of the optical head 12 according to the output of the switch 18 to access a target track.

In FIGS. 4 and 5, the symbol D□ is a feature of the present invention.
The configuration method and its features will be explained. Figure 4 shows
FIG. 3 is a diagram of address pits and their reproduced waveforms. Figure 4(a)
is an address pit, and the address pit has the characteristics of the code of the present invention.

As an example, the reproduced signal of the address pit part has the code Dsz.
=) The reproduction signal of rack number 10 is shown in Fig. 4 Φ),
The reproduction signal of code D□-track number 11 is shown in Fig. 4(d).
It is indicated by. During access, the optical head
, 50 and 60, their trajectories pass differently as shown by the broken lines. When the optical head has a trajectory of 60, the reproduced signal becomes as shown in FIG. 4(C). In the code arrangement using the code of the present invention, the reproduced signal is subjected to ^/D conversion at each digit position based on the characteristics of adjacent codes, and two samples are determined to be "1" based on the maximum value. By this method, in the case of the waveforms shown in Fig. 4 (L) and (d), as well as in the case of the waveform shown in Fig. 4 (C), the determination sign is determined by track (n-1)
The sign of...

or the code D (+1+1)* of track nXM+1, and the detection capability can be increased without depending on changes in the reproduced signal level. On the other hand, “1” of each code
When the number of "01" digits (referred to as run length) between "1#" and "1#" is R, the condition R>=1 is a value that takes into account code amount interference.

Next, let the number of digits of the code be K, and consider the cyclic number N when the above-mentioned R is arbitrarily selected. FIG. 5 shows an explanatory diagram thereof. A in D0 in Fig. 5(a)
Assume that (nm, i) and A (nm, j) have logic "l", and in this case, i is 1 to (K-
Consider a lattice diagram with j equal to (R+1). However, K−R)>2.

The generation method of the present invention starts from an arbitrary lattice and shifts to a lattice shifted in the i or j direction. All routes that move and finally return to the initial grid position are acceptable methods. However, passing through the same grid twice is prohibited. When K and R are given, the maximum N is given by the maximum integer value that satisfies the following formula.

However, K-R>2.

As an example of the present invention, consider the code shown in FIG. 1, and calculate the relative track number (n-1)xM+1 from this code string. In this case, the sign. 1 is D, , -(A (nm, 1
), A (nm, 2), ~A (r++++
.

5), A (nm, 6)). Do, D, , 1- (A (ns, 1), A (n
s, 2), A (nm, 3) ID,, 2-
(A (nm, 4), A (n+w, 5)
, A (nm, 6)). The position of digit "1" in each code is from 0 to 20,
The address value is expressed as a 2-bit binary number below.

V1=yO+2*yl V2=zO+2*zl Relative address number (n-1) M+1 is expressed by the following formula % Formula % FIG. 6 shows a specific embodiment of the address pit pattern detector 20. FIG. 7 is an explanatory diagram of the waveform. In FIG. 6, the reproduced signal RF reproduced from the disk and converted into a voltage signal is input to the input terminal 36, and is converted into a digital value DS by the A/D converter 21 at the sampling position of the input clock CL. The input clock CL is a signal generated by a PLL circuit from the aforementioned clock bits. The converted digital signal port S is input to first half and second half code pattern detectors 34 and 35. Terminals 30 and 32 have a detection separation gauge signal sci
and SC2 are input. Here, the code pattern detector 34 in the first half will be explained. Now, if the digital reconnaissance signal S of the input signal takes a value as shown in FIG. 7 (8), the value of the separated digital value DSI that has passed through the AND gate 22 is It will be like this.

Next, via the latch circuit 23, the signal separation digital value D
The SI and latch output LSI are input to a comparator 24. When the value of the separated digital value DSL becomes larger than the latch output LSI, the output of the comparator 24 becomes "H", and the value is latched and transferred to the latch output LSI. In this example, the value of the latch output LSI is as shown in FIG. 7(1). The one-shot multi 25 is driven by the launch output LSI at this time, and its output is shown in FIG.
A pulse TP shown in J) is generated. This pulse TP sets the counter 26 to the number of day shifts of the pattern, 2 (in this case, it is 3 bits and takes a value of 0 to 2, so it is 2), and when no pulse is generated, that value is set to the clock. td). On the other hand, the gate signal SCI is configured to be cleared during the "L" period, and when the separation gate signal SCI ends, the output signal CO of the counter is latched by the latch circuit 27, and the output signal L
The value of S2 becomes 1 as shown in FIG. 7 (Tl), and is outputted to the output terminal 31 as a 2-bit binary code signal.

Similarly, a code indicating the second half bit position is also outputted to the output terminal 33 as a value 2 at the timing shown in FIG. 7(E).

By processing this signal output in the logic circuit of the algorithm for calculating the track number described above, a relative track address is created in binary code. The speed detector 15 and direction detection circuit 16 of FIG. 3 utilize this change in relative track address during access to set its value. For example, the time between servo sectors is known because the rotational 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. Speed can be determined from time and distance. Furthermore, the direction can be determined from changes in the value of the relative track address.

These determinations can be easily processed by a microcomputer. In the configuration of FIG. 3, a light spot,
That is, when the optical radar 12 moves toward the outer circumference, the output of the direction detection circuit 16 is at "H" level, when it moves toward the inner circumference, it is at "L" level, and the polarity of the output from the direction detection circuit 16 is at "H" level. When the switch 18 is on the side of the speed detector 15, “
By switching to the inverting amplifier circuit 17 side when the signal is L", the analog input signal of the speed control circuit 19 becomes a signal having information on the direction of movement toward the outer circumference when positive and toward the inner circumference when negative. In this way, even if the direction is reversed during the access operation, the speed control system will not enter positive feedback, making stable control possible.

Next, consider the effect of increasing track density. It was explained earlier that increasing the trunk density is affected by adjacent tracks. Consider the example of FIG. 1 as a pit pattern arrangement of a servo field according to the present invention. The wobble pits and clock pits have the same pit positions on adjacent tracks, and interference of unbalanced signals to each pit does not occur as in the conventional example. Therefore, no deterioration of tracking performance or clock focus detection performance occurs. Furthermore, although the detection ability during access is a problem with address focus, it is clear that the performance does not deteriorate as explained with reference to FIG.

As explained above, the use of the address pit pattern of the present invention provides the following advantages.

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

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

(3) Track number decoding hardware can be easily configured based on the detection pattern.

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

(5) Tracking performance and access performance do not deteriorate even if the track density is increased.

(6) Even if access is made at high speed, there is little change in the track identification pattern, and false detections can be reduced.

Furthermore, in the above embodiment, the case where the entire optical head is driven for access has been explained, but in the case of a separate type optical head,
Needless to say, the present invention can also be applied when accessing a part of the 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.

〔Effect of the invention〕

As described above, in the optical disk of the first invention, the "1" pits between adjacent blocks and between the first and last blocks of a cycle are only shifted by one bit, so even if the access operation is high speed, the pattern changes. This makes it possible to reliably detect the track position and direction with less noise, and to increase the resolution of track counting. Additionally, track density can be improved. 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 is a pattern configuration diagram showing a first embodiment of the pit pattern of the optical disc of the first invention, FIG. 2 is a pattern configuration diagram showing the second embodiment of the bit pattern of the optical disc of the first invention, FIG. 3 is an explanatory diagram of a code structure showing an embodiment of the optical disk drive device of the second invention, FIG. 6 is a circuit diagram showing a specific example of the address pit pattern detector of FIG. 3, and FIG. 6 is an explanatory waveform diagram of the operation, FIG. 8 is an explanatory diagram showing the track/sector format of a conventional optical disk, FIG. 9 is a pit pattern configuration diagram of a conventional optical disk, and FIG. 10 is a servo field of a conventional optical disk. FIG. 3 is an explanatory diagram showing the structure and how a light spot scans over the disk. 4.5...Address pit 11...Optical disc 1
2... Optical head 13... Photodetector 15 Speed detector 16... Direction detection circuit 19... Speed control circuit 20... Address pit pattern detector In addition, in the figure,
The same reference numerals indicate the same or equivalent parts. Agent: Masuo Oiwa<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<> Representative 4 of the person making the amendment, Substitute 5, Column 6 of “Detailed Description of the Invention” of the specification to be amended, Contents of the amendment (1) “Also D
``1 track away from nus'' is replaced with ``1 track away from nus''.
"It was one block away," he corrected. (2) In the 5th line of page 16 of the specification, r=l+2x (v
1+V2+3IO*Z 1*2J is replaced with "-1+2
*Corrected to (V1+V2+yO*zl*2). (3) In the 16th page, line 17 of the specification, the phrase "Separated gauge signal for detection" is corrected to "Separated gate signal for detection."

Claims (2)

[Claims] (1) In an optical disc having a plurality of concentric or spiral tracks and an address pit formed in the track and recording an address therein, the address pit consists of two bits sandwiching one or more random bits. The pattern is formed at the significant bit position of a K-bit pattern having significant bits, and the pattern changes for each block with M (M: natural number) tracks as one block, and repeats the change at a cycle of N blocks, An optical disc characterized in that patterns between adjacent blocks and between a first block and an Nth block of a period are formed by shifting one digit of two significant bits by one bit. (2) A device for driving the optical disc according to claim 1, which is movable in the radial direction of the optical disc, and is capable of irradiating the optical disc with light, detecting the light from the light, and converting the light into an electrical signal. a head; a pattern detector for detecting a pattern of the address pits based on the electrical signal; a direction detecting means for detecting a moving direction of the optical head from the order of changes in the detected pattern; An optical disk drive apparatus comprising: a speed detecting means for detecting a relative speed in a radial direction between the optical head and the optical head; and a speed controlling means for controlling the speed of the optical head based on the moving direction and the relative speed.