JP3068105B2 - Information recording medium and its recording / reproducing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium suitable for recording / reproducing information on an optical disk, for example, and a recording / reproducing apparatus therefor.

[0002]

2. Description of the Related Art In a conventional optical disk, a servo byte section is periodically provided at a predetermined position on each track, and a clock pit for generating a reference clock and a wobbled pit for tracking are provided in each servo byte section. Is formed. Then, a reference clock (channel clock) is generated corresponding to the clock pit, and information is digitally recorded by a pit having a length that is an integral multiple of the period of the reference clock.

In a compact disk, for example, there are no clock pits, but the length is also an integral multiple of the period of the reference clock (channel clock) (0.
Information is digitally recorded by pits of 9 μm to 3.3 μm).

[0004]

As described above, conventional optical disks and compact disks form pits having a length that is an integral multiple of the period of a reference clock (channel clock), and the length of the pit is Since information is recorded correspondingly, there is a problem that it is difficult to improve the recording density.

For example, if it is attempted to record a 0.9 μm pit immediately after a 3.3 μm pit is recorded, a disk (recording master) is recorded while the 3.3 μm pit is being recorded due to a so-called heat storage effect. 0.9 to warm up
μm pits are formed larger than expected. As a result, the signal is distorted, and the reading margin of the digital signal is reduced accordingly.

The present invention has been made in view of such circumstances, and has been made to further improve the recording density.

[0007]

According to the present invention, there is provided an information recording apparatus , wherein the number of rising edges or falling edges of information pits is small.
At least one edge position from a predetermined reference position,
Stepwise at any of two or more predetermined positions
The multi-value information is represented by shifting
Characterized in that it comprises a first recording means for recording

[0008] The first recording means is a rising edge of the information pit.
The position of the edge is determined based on the recorded information based on the rising edge.
From the sub-position to any one of two or more predetermined positions,
The first multi-value information is represented by shifting it in steps.
And the position of the falling edge of the information pit
Is the reference position of the falling edge according to the recorded information.
Step at any one of two or more predetermined positions
To represent the second multi-valued information by shifting
To record two pieces of multi-valued information in one information pit
Can be.

In an information recording medium, a plurality of information pits
The rising or falling edge of the
The position of the edge records the position reference pit that indicates the reference position.
Second recording means can be further provided.

[0010] An information recording medium according to claim 4 is an information recording medium.
Is low on its rising or falling edge.
The position of one of the edges is a predetermined base corresponding to the multi-valued information.
From the reference position to any one of two or more predetermined positions.
Characterized in that it is formed so as to change
You.

At a predetermined ratio for a plurality of information pits,
The position of the edge is a position reference pit representing the reference position.
Can be formed.

The phase of the information pit is shifted to the adjacent track.
At 90 degrees.

[0013] The information recording method according to claim 7 is an information recording method.
At least one of the rising or falling edges of the
Position of the other edge two or more from the predetermined reference position
Stepping to one of the fixed positions
To represent multi-valued information and record the multi-valued information
It is characterized by including a recording step.

An information reproducing apparatus according to claim 8 is an information reproducing apparatus.
Edge detection means for detecting the edge of a bit, and edge detection
The position of the edge of the information pit detected by the
Any of two or more positions shifted stepwise from the reference position
Position, and based on the result of the determination,
Judgment means for obtaining a corresponding value of the report
It is characterized by.

An information recording medium has a plurality of information pits.
The rising edge or
Position reference pit where the falling edge position indicates the reference position
Is recorded, and the edge detecting means detects the position reference pit.
The edge whose position represents the reference position is also detected, and the edge is detected.
The position of the edge of the position reference pit detected by the means
Storage means for storing the
The position of the edge of the information pit is stored in the storage means.
Correction means for correcting at the position of the edge of the position reference pit
Can be further provided, and the determining means is provided in the correcting means.
The position of the edge of the information pit corrected by
Can be.

[0016] The correction means is detected by the edge detection means.
Value read as the position of the edge of the read information pit
The edge of the position reference pit stored in the storage means
Correction is performed by subtracting the value read as the position of
I can.

[0017] In the information reproducing method according to the eleventh aspect, the information
An edge detection step for detecting a pit edge;
Edge of the information pit detected in the processing of the edge detection step
Are two or more positions displaced in a step from the reference position.
Position is determined, and based on the determination result,
The determination step for finding the corresponding value of the multi-valued information.
And a pump.

[0018]

[0019]

[0020]

The information recording apparatus according to claim 1 and claim 7.
The information recording method described in
Edge or at least one of the falling edges
The position is defined as two or more predetermined positions from a predetermined reference position.
Multi-valued information can be obtained by shifting the
The multi-value information is recorded so as to represent the information.

[0021] In the information recording medium according to claim 4,
Indicates that the information pit has its rising or falling edge
The position of at least one edge of the edge corresponds to the multi-valued information.
Any of two or more predetermined positions from the predetermined reference position
It is formed so as to change stepwise in position.

An information reproducing apparatus according to claim 8 and an information reproducing apparatus according to claim 11.
In the information reproducing method described in (1), the edge of the information pit
Is detected, and the position of the edge of the detected information pit is
Any of two or more positions shifted stepwise from the reference position
Is determined, and based on the determination result,
The corresponding value of the value information is determined.

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the information recording medium of the present invention and its recording / reproducing apparatus will be described. FIG. 1 shows the principle of recording according to the present invention. As shown in the figure, in the present invention, the position of at least one of the rising edge and the falling edge of the information pit (both in the embodiment) is
It is shifted stepwise from the reference edge position in accordance with the digital recording information. That is, the edge position (zero cross position) of the recording signal shown in FIG. 1B is delayed stepwise by a predetermined time corresponding to the recording information, with the rising edge position of the reference clock shown in FIG. 1C as a reference position. Or advanced. In the embodiment, the position of the edge is moved from the reference position to the right side in the figure because of the delay, but if it is advanced temporally, it is moved to the left side in the figure. Assuming that each edge represents, for example, 3-bit digital data (that is, 0 to 7), each edge is formed at a reference position when the data is 0, and is delayed by a unit time (one step) when the data is 1; 2
Is delayed by twice the unit time (2 steps).
In this case, the time is delayed by three times (3 steps) the unit time. Similarly, when the data is 7, the edge is delayed by 7 times the unit time (7 steps).

When information is recorded in this manner, information pits are formed on an optical disc as an information recording medium, for example, as shown in FIG. 1A. The information pits can be formed as physical recesses or protrusions, or can be formed by making the properties (for example, reflectance or transmittance) of the information recording medium different from other parts. Good. In the embodiment, the rising edge and the falling edge of the first information pit following the position reference pit (this position reference pit will be described later in detail) represent 3 and 7, and the rising of the next information pit. Edges and falling edges represent 0 and 4. Assuming that the length on the recording medium corresponding to the unit time (one step) of the delay of the recording signal is, for example, 0.05 μm, the respective edges are 3 × 0.05 μm, 7 × 0.05 μm, 0 × 0 μm from the reference position.
It is moved to the right side in the figure by × 0.05 μm and 4 × 0.05 μm. The length on the optical disk corresponding to one cycle of the reference clock (the length when both the rising edge and the falling edge are not delayed) is 1.2 μm.
Is set to

As described above, in order to shift the edge of the information pit from the reference position corresponding to the digital recording information, it is necessary to clarify the reference position of the edge. Therefore, in the information recording medium, as shown in FIG. 2, PLL pits (clock pits) have a constant period (for example, one pit of an optical disc).
The rotation is divided into 4200 sectors, one servo area is provided in each sector, and one servo area is recorded in each servo area. When information is recorded, the PLL pit (clock pit) is reproduced, and a reference clock (FIG. 1C) is generated in synchronization with the reproduction. Then, the reference position of the edge is determined with reference to this reference clock (in the embodiment of FIG. 1, the rising edge of the reference clock is the reference position of the edge of the information pit). A plurality of information pits are formed between the clock pits.

FIG. 3 shows the principle at the time of reproduction.
At the time of reproduction, the optical disk on which information is recorded as shown in FIGS. 1 and 2 is reproduced to obtain an RF signal as shown in FIG. 3A. When this RF signal is amplified and binarized, a binarized RF signal as shown in FIG. 3B is obtained.
A clock pit (PLL pit) component is separated from the binary RF signal, and a reference clock as shown in FIG. 3C is generated in synchronization with the clock pit (PLL pit) component. Further, in synchronism with this reference clock, a saw-tooth wave signal (a triangular wave signal may be generated) as shown in FIG. 3D is generated.

This sawtooth signal has the maximum value level (255) immediately before the falling edge of the reference clock, and
After the fall, the voltage suddenly drops to the lowest level (0) and then linearly increases again to the maximum value. Therefore, the level of 256 steps can be determined from the sawtooth signal. Therefore, the binary RF signal (FIG. 3)
B), the level of the sawtooth signal (FIG. 3D) at the timing of the rising edge and the falling edge (displacement of the edge of the information pit) is detected.
The level (reference position of the edge of the information pit) of the sawtooth signal (FIG. 3D) at the rising edge of C) is detected, and the difference from the reference position of the edge of the information pit (that is, the recording data) is determined from the difference between the two. Can be detected.

If the sensitivity of the optical disk varies, or if the recording laser power varies with time, the pits formed also vary. FIG. 4 shows this state. That is, when the recording laser light of the same level (intensity) is irradiated, the length of the pit formed is shorter when the sensitivity of the optical disc is low than when the sensitivity is high. Further, even if the sensitivity is constant, a similar variation occurs when the power of the recording laser beam fluctuates.

If there is such a variation, it is difficult to form the edge at an accurate position, that is, to record accurate information. Therefore, in this embodiment, in addition to the reference pits (PLL pits), position reference pits are further recorded at a constant cycle. In this embodiment, one position reference pit is formed immediately after the clock pit (that is, one position reference pit), and thereafter, a plurality of information pits are formed. In the position reference pit, both the rising edge and the falling edge are always located at the reference position (the position of the rising edge of the reference clock).

Next, the operation of the position reference pit will be described with reference to FIG. In this embodiment, FIG.
As shown in A, since the first pit is a position reference pit, data corresponding to both edges thereof is set to 0. The rising and falling edges of the three information pits after the position reference pit are 3 and 0, 2 and 5, 1 and 0
Are associated with each other. Therefore, assuming that the optical disk has an appropriate sensitivity, a position reference pit and an information pit as shown in FIG. 5C are formed on the optical disk corresponding to the recording signal (recording pulse) as shown in FIG. 5B. You.

At the time of reproduction, the rising and falling edges of each pit are detected, and when the level of the sawtooth wave signal shown in FIG. 5D at the detection timing is read, the values at the rising and falling edges of the position reference pit are: If both are 64, the rising and falling edges of the three information pits are detected, and when the level of the sawtooth signal at the detection timing is detected, as shown in FIG. 76 and 94, 70 and 64
become. To determine the deviation of each value from the reference position,
As described above, the level of the sawtooth signal at the rising edge of the reference clock in each pit may be read and the value may be subtracted. Incidentally, the level of the sawtooth signal at the timing of the edge of the reference clock is the same as the level of the position reference pit. Therefore, instead of reading the level of the sawtooth signal corresponding to the edge of the reference clock for each pit, the level of the sawtooth signal at the rising and falling edges of this position reference pit is
It can be used as the level of the sawtooth signal corresponding to the edge of the reference clock for each pit (the position reference pit has a second utility in addition to a sensitivity correction action (first utility) described later). ).

In the case of this embodiment, the values shown in FIG.
5F by subtracting the values 64 and 64 in the position reference pit from 2 and 64, 76 and 94, and 70 and 64.
As shown in the table below,
18 and 0, 12 and 30, 6 and 0 can be obtained. Since the value 6 of the shift amount corresponds to the unit delay time described above, the data can be obtained as 3 and 0, 2 and 5, 1 and 0 by dividing these values by 6. . These values are the same as the original data shown in FIG. 5A.

On the other hand, when the sensitivity of the optical disk is, for example, too high, corresponding to the recording pulse shown in FIG.
As shown in FIG. 5G, the position reference pit and the information pit are formed longer than in the case of the appropriate sensitivity shown in FIG. 5C.
This variation in sensitivity is substantially constant for one optical disk even if there is variation for each optical disk. Even if there is a local variation in one optical disc, it is considered that the variation is substantially constant at least within the range of the cycle (within one sector) in which the position reference pits are formed.

Therefore, for example, as shown in FIG. 5I, assuming that the position of the rising edge in the position reference pit is reduced by 10 in terms of the level of the sawtooth signal (FIG. 5H) from the original reference position. The position of the falling edge is also increased by 10 in terms of the level of the sawtooth signal from the original reference position, and is 54 (= 64−10) and 74.
(= 64 + 10). Similarly, at the rising edge and the falling edge of each information pit, the level is reduced or increased by 10 in terms of the level of the sawtooth signal from the original recording position. That is, the values of the sawtooth signal (FIG. 5H) at the timing of the rising edge and the falling edge of each information pit (FIG. 5G) are 72 (= 82-10) and 74, respectively, as shown in FIG. 5I.
(= 64 + 10), 66 (= 76−10) and 104 (=
94 + 10), 60 (= 70-10) and 74 (= 64 +
10).

Accordingly, these information pit values 72 and 7
4, 66 and 104, 60 and 74 to the reference pit value 54
And 74, 18 and 0, as shown in FIG. 5J,
12 and 30, 6 and 0 are obtained. These values are shown in FIG.
(This is the first utility of the position reference pit).

Although the case where the sensitivity is too high has been described above as an example, when the sensitivity is too low, the sensitivity of the information pit is shortened by the same length as the edge of the position reference pit. As in the case of too high, the same data as in the case of the appropriate sensitivity can be obtained.

That is, by forming the position reference pits in this way, it is not only unnecessary to read the sawtooth wave signal for each reference clock of each pit, but also correct even if there is a variation in sensitivity or the like. Data can be recorded and reproduced.

FIGS. 6 and 7 illustrate the effect of correction by the position reference pit. In each of these figures,
The horizontal axis represents time, and the vertical axis represents voltage. The voltage on the vertical axis is obtained by converting data from 0 to 7 described in FIG. 1 into a voltage. That is, if the deviation of the edge obtained at a certain time (a predetermined position on the horizontal axis) from the reference position (this deviation is any one of 0 to 7 as described above) is 0, the edge is determined as It is expressed by the point of the lowest predetermined voltage, and if the deviation is 7, it is expressed by the point of the highest predetermined voltage. The data represented by each edge of the information pits reproduced one after another in this manner is represented as a point of a predetermined voltage (the output of a D / A converter 47 shown in FIG. 18 to be described later is monitored). Thus, such a waveform is obtained).

FIG. 6 shows a state in which the correction using the position reference pit is not performed. In the case of this figure, the points that should be aligned on a horizontal line indicating a constant voltage for each of the data 0 to 7 are greatly shifted in the vertical axis direction.
This means that, for example, even at the edge representing the same data of 5, the deviation from the reference position may be large (for example, the deviation amount (voltage) originally representing the data 7) or small (for example, the original data 3). Or a shift amount (voltage) indicating the shift) or a shift in the shift. In order to read (identify) which data is 0 to 7, a voltage (shift amount) representing one data (eg, 5) and a voltage (shift amount) representing adjacent data (eg, 6) It is necessary to determine whether the voltage is larger or smaller than the threshold value by setting a voltage intermediate between the threshold values. However, when the voltage representing each data fluctuates as shown in FIG. 6, it is difficult to read (identify) the data (whether it is 5 or 6) with reference to a fixed predetermined threshold voltage. I can no longer do it.

On the other hand, FIG. 7 shows a case where the correction is performed by the position reference pit. In this case, it can be seen that the voltage (deviation amount) of each data becomes constant. Therefore, in this case, each data can be easily identified based on the predetermined threshold.

FIG. 8 shows the relationship between pits (position reference pits and information pits) on adjacent tracks. In the case of a CAV (constant rotation angular velocity) disk, as shown in the figure, the pit phase (data is 0) of adjacent tracks (odd-numbered tracks and even-numbered tracks).
Is shifted by 90 degrees. In other words,
When the data is 0, the phase of the recording signal is shifted by 90 degrees. This also means that when focusing on the phase of the reference clock, the phase of the reference clock of the odd-numbered track is shifted by 180 degrees from the phase of the reference clock of the even-numbered track. In this manner, when the edge of one position reference pit or information pit of one track is reproduced by one light spot, the edge of the adjacent track is not located within that light spot, Less talk. Therefore, the track pitch can be narrowed and higher density can be realized.

Next, a tracking method will be described. A so-called three-spot (beam) method is known as one of the tracking methods. In this method, as shown in FIG. 9, in addition to a main beam (spot) for originally reproducing information, two sub-beams (spots) are arranged on both sides of the main beam (spot). By arranging the sub-beams on the left and right edges with respect to the traveling direction of the track,
Light reflected from the three sub-beams is detected by a photodetector, and a tracking error signal can be obtained from the difference between the outputs. However, this method, as shown in FIG.
When the track pitch is narrowed, the sub-beam reads information on an adjacent track, so that a tracking error signal cannot be generated.

Some optical disks employ a so-called sample servo system. In this method, as shown in FIG. 11, wobbled pits are arranged at positions slightly shifted left and right from the center of the track and slightly shifted in the track direction. A tracking error signal can be generated from the difference between the levels of the reproduced signals of the two wobbled pits. However, if the track pitch is narrowed in this method, as shown in FIG. 12, wobbled pits for adjacent tracks interfere with each other, and it is impossible to generate a correct tracking error signal.

Therefore, in this embodiment, the sample servo system shown in FIG. 11 is basically employed. However, as shown in FIG. 13, one clock arranged on the center line of the track is provided in the servo area. Two wobbled pits are arranged so as to deviate from the pit (PLL pit) to the left and right with respect to the center line of the track and also to the track direction (to face the clock pit). These pits are recorded (formed) as prepits before recording the original information, for example, as physical irregularities. Each wobbled pit is arranged so that it can be shared by adjacent tracks. In other words,
The wobbled pits are arranged at the center of the track and the furnishings of the tracks, and one wobbled pit is used for both left and right tracking. By doing this,
The track pitch can be reduced and a tracking error signal can be generated.

However, when one wobbled pit is used for both the left and right tracks, it is necessary to invert the polarity of the tracking servo between the odd track and the even track. An embodiment in this case will be described later with reference to FIG.

In the case where the positions of the position reference pit and the information pit are shifted by 90 degrees between the odd track and the even track, as shown in FIG. 13, for example, one of the even track or the odd track (in the embodiment, the even track or the odd track) is used. truck)
Is shifted behind the last information pit of the other track (an odd track in the embodiment). That is, when observed on the time axis (on the reproduction signal), the last information pit appears later in the even track than in the odd track. Alternatively, focusing on the position reference pits located immediately after the clock pits, the position reference pits appear later in the even-numbered tracks than in the odd-numbered tracks. Therefore, the occurrence timing of this last information pit or position reference pit can be detected, and then an odd track or an even track can be determined. This embodiment will also be described later with reference to FIG.

Next, in order to clarify the characteristics of the information recording method according to the present invention, the conventional recording method and the recording method of the present invention are compared with reference to FIG. In a conventional sample servo type optical disk, as shown in FIG. 14A, a reference clock (channel clock) is generated in synchronization with a clock pit. A pit having a length that is an integral multiple of the period of the reference clock is defined as one unit. Which length of the pit is formed is determined by the recorded information.

In the compact disk, no clock pits are formed. However, as shown in FIG. 14B, a pit having a length which is an integral multiple of the period of the reference clock (channel clock) is formed as one unit. Is done.

On the other hand, in the embodiment of the present invention,
14C, the reference clock is generated in synchronization with the clock pit (PLL pit) as shown in FIG.
Same as in A. However, the length of the information pit is basically the length of the period of the reference clock (the position of the edge in this case is the reference position),
The length of the edge (the position of the edge) is changed corresponding to the recording data, but what is significant as information is the amount of deviation of the edge from the reference position. Therefore, in the present embodiment, the length of the information pit is set within a range from one time to twice the period of the reference clock.

As is apparent from a comparison between FIG. 14C and FIGS. 14A and 14B, according to the present embodiment, information can be recorded at a higher density. Then, in order to determine a more accurate reference position, a position reference pit is inserted in addition to the clock pit as necessary.

In the case of a compact disk, the track pitch is 1.6 μm, and the recording density is 0.6 μm per bit.
It is. On the other hand, in this embodiment, the track pitch is 1.2 μm and the recording density is 0.4
μm. As a result, a recording density twice as large as that of a compact disc is realized.

Next, an embodiment of an apparatus for realizing the above recording and reproduction will be described. FIG. 15 shows a partial configuration of the recording apparatus. The data output circuit 51 performs A / D conversion of a signal supplied from a circuit (not shown), performs predetermined processing, and outputs the result to an error correction (ECC) circuit 52.
The error correction circuit 52 performs processing such as addition of an error detection and correction code and interleaving on the input digital data. The data length conversion circuit 53 converts, for example, data in units of 8 bits input from the error correction circuit 52 into data in units of 3 bits. This 3-bit unit data is shown in FIG.
6 is supplied to the recording device.

The terminal 11 shown in FIG. 16 has a reference clock (FIG. 1).
7A) is supplied. The reference clock is generated, for example, by a PLL circuit 31 of FIG. 18 described later in synchronization with a clock pit of the optical disk. This reference clock is supplied to the delay line 15 via the buffer 12 and the switch 14. The switch 14 is switched to the contact a side for odd tracks and to the contact b side for even tracks. When the reference clock is switched to the contact b side, the reference clock is inverted by the inverter 13 and input to the delay line 15. The other end of the delay line 15 is a resistor 1
6 is grounded.

The delay line 15 has eight output terminals each having a corresponding buffer 17, and each output has a different delay time per unit time. That is, this unit time is calculated as shown in FIG.
0.05 μm on the optical disc described in
Is set to the time corresponding to the length. That is, a reference clock delayed by a unit time × 0 to a unit time × 7 times is output from each output terminal. The data selector 10 includes a data length conversion circuit 53
One of the eight output terminals is selected in accordance with the 3-bit data supplied from the terminal. That is, when data is 0, an output terminal having a delay time of unit time × 0 (that is, outputting a reference clock without delay) is selected, and when data is 5, an output terminal having a delay time of unit time × 5 is selected. I do. As a result, the reference clock is delayed stepwise with the unit time as one step by the time corresponding to the digital data. In the case of recording the position reference pit, 0 is set as the data in the data selector 1
Input to 0. Therefore, a reference clock that is not delayed is output from the data selector 10.

The T-type flip-flop 18 is triggered by the rising edge of the output of the data selector 10, and the logic of the output is inverted each time the trigger is triggered. The output of the T-type flip-flop 18 is supplied to one input of an AND gate 20.

The N-ary counter 23 counts a reference clock. The decoder 24 detects the count value of this counter and generates a signal of the section logic L of the servo area of each sector and a signal of the section logic H of the data (FIG. 17B), which are connected to the reset terminal of the T-type flip-flop 18 and the AND gate. 20
To the other input.

As a result, in the data section, the AND gate 20 becomes conductive, so that the recording pulse whose rising and falling edges are delayed stepwise by the time corresponding to the 3-bit data output from the T-type flip-flop 18 (FIG. 17C) is output via the AND gate 20. The signal output from the AND gate 20 is supplied as a recording signal to an optical disk to a recording head (not shown), and is recorded on the optical disk. In the servo area section, the AND gate 20 becomes non-conductive, and the output of the recording signal generated by the T-type flip-flop 18 is prohibited.

Next, a reproducing apparatus will be described with reference to FIG. The reproduced RF signal reproduced from the optical disc is P
It is input to the LL circuit 31 and the equalizer 34. PL
The L circuit 31 extracts a component based on the above-described clock pit (PLL pit) from the RF signal (FIG. 3A), generates a reference clock (FIG. 3C), and supplies the reference clock to the sawtooth wave oscillator 33. The saw-tooth wave oscillator 33 generates a saw-tooth wave signal (FIG. 3D) in synchronization with the input reference clock, and outputs the signal to A / D converters 36 and 37. The reference clock generated by the PLL circuit 31 is also supplied to the timing controller 32. The timing controller 32 synchronizes with the reference clock and generates a latch pulse at the timing of the rising edge of the position reference pit (FIG. 3A). 40
And a latch pulse is supplied to the latch circuit 42 at the timing of the falling edge.

The equalizer 34 processes the input RF signal into a predetermined frequency and phase characteristic, and
5 is output. The binarization circuit 35 binarizes the input RF signal. This binarized RF signal (FIG. 3B) is input to the clock terminal of the A / D converter 36 and the clock terminal of the latch circuit 39, and after being inverted by the inverter 38, the clock signal of the A / D converter 37 and the latch. It is supplied to the clock terminal of the circuit 41.

Therefore, in the A / D converter 36, the level of the sawtooth signal (FIG. 3D) at the timing of the rising edge of the binary RF signal is sampled, and the sampled value is A / D converted. As described above, the level of the sawtooth wave signal is decomposed into 256 steps, and this sample value is output to the latch circuits 39 and 40 as 8-bit data. The latch circuit 39 latches the output of the A / D converter 36 at the timing of the rising edge of the binarized RF signal output from the binarization circuit 35.
The latch circuit 40 latches the output of the A / D converter 36 at the timing of the rising edge of the position reference pit output from the timing controller 32.

In this manner, the data of the rising edge of the position reference pit (data of the reference position) described with reference to FIG. 5E.
The data 64 (or the data of the rising edge of the position reference pit described in FIG. 5I) is latched by the latch circuit 40. Also, the data of the rising edge of the information pit (data shifted from the reference position) 82, 76, 70 described in FIG. 5E, or the data of the rising edge of the information pit described in FIG. 5I (data shifted from the reference position) 72, 66, and 60 are latched by the latch circuit 39. The subtractor 43 subtracts the latch data of the latch circuit 40 from the latch data of the latch circuit 39. Thus, the values 18, 12, 6 representing the deviation of the rising edge of the information pit from the reference position described in FIG. 5F or the deviation of the rising edge of the information pit from the reference position described in FIG. The obtained values 18, 12, 6 are obtained.

The 8-bit data output from the subtractor 43 is converted into 3-bit data by the conversion map circuit 45 and output. When the output of the subtracter 43 is D / A converted by the D / A converter 47 and monitored, the characteristics shown in FIG. 7 (or FIG. 6) can be observed as described above.

On the other hand, in the A / D converter 37,
The level of the sawtooth signal at the timing of the falling edge of the binarized RF signal is sampled, and the sampled value is A / D converted. This sample value is output to the latch circuits 41 and 42 as 8-bit data. The latch circuit 41 latches the output of the A / D converter 37 at the timing of the falling edge of the binarized RF signal output from the binarization circuit 35. The latch circuit 42 latches the output of the A / D converter 37 at the timing of the falling edge of the position reference pit output from the timing controller 32.

In this manner, the data of the falling edge of the position reference pit (data of the reference position) described with reference to FIG. 5E.
64 or the data 74 of the falling edge of the position reference pit (reference position data) 74 described with reference to FIG. Further, the data of the falling edge of the information pit (data shifted from the reference position) 64, 94, 64 described in FIG. 5E or the data of the falling edge of the information pit described in FIG. Data) 74, 104 and 74 are latched by the latch circuit 41. The subtractor 44 subtracts the latch data of the latch circuit 42 from the latch data of the latch circuit 41. Thus, the value 0, 30, 0 representing the deviation of the falling edge of the information pit from the reference position described in FIG. 5F or the deviation from the reference position of the falling edge of the information pit described in FIG. In addition, corrected values 0, 30, and 0 are obtained.

The 8-bit data output from the subtractor 44 is converted into 3-bit data by the conversion map circuit 46 and output.

In the above description, two A / D converters are used. However, signals supplied from the binarization circuit 35 or the inverter 38 are alternately supplied to the clock terminals of the A / D converters. It can be individual. Further, a sample and hold circuit can be used instead of the A / D converter. Further, a counting clock having a frequency sufficiently higher than that of the counting clock is generated at a predetermined period in synchronization with the reference clock, and the counting clock is counted by a counter. Even if the latch is performed at the timing of the falling edge, the edge shift can be detected.

In the above description, the data of the position reference pit for each sector is independently latched in the latch circuits 40 and 42 and used for correction. However, the average value of the values in a plurality of sectors is obtained. This can be used for correction. By doing so, the reliability can be further improved.

FIG. 19 shows an optical disk having a format in which wobbled pits are common to adjacent tracks and the phases of position reference pits and information pits are shifted by 90 degrees between adjacent tracks, as shown in FIGS. 8 and 13. 5 shows an example of a configuration in which an odd track and an even track are determined, and the polarity of the tracking servo is switched in accordance with the determination result. In this embodiment, the reproduction RF signal reproduced and output from the optical disk is
1 and the sample and hold circuit 63. PL
The L circuit 61 generates a reference clock from a component corresponding to the reference pit, and outputs it to the timing circuit 62. The timing circuit 62 generates various timing signals synchronized with the reference clock supplied from the PLL circuit 61 and supplies them to the sample and hold circuits 63, 66, and 67.

As already described with reference to FIG. 13, when the phase of the pit is shifted by 90 degrees, the generation timing of the last information pit (or position reference pit) differs between the odd track and the even track. The timing circuit 62 outputs a sampling pulse to the sample and hold circuit 63 at a timing T (see FIG. 13) in which the last information pit exists in the even track and the last information pit does not exist in the odd track. In the even track, the level of the RF signal at the timing when the sampling pulse is input is small because the information pit exists. On the other hand, since the information pit does not exist in the odd track, the level of the RF signal is higher than that in the even track.

Therefore, the level of the RF signal at the timing when the sampling pulse is input is sampled and held by the sample and hold circuit 63, and the sample and hold value is compared in the comparison circuit 64 by the reference voltage generation circuit 65.
Is compared with the output reference voltage. This reference voltage is set to an intermediate value between the sample and hold value in the odd track and the sample and hold value in the even track.
Therefore, the output of the comparison circuit 64 is at a high level for an odd-numbered track, and is at a low level for an even-numbered track. This output is used for switching the switch 14 in FIG. 16 and also for switching the switch 68 of the tracking servo circuit 80.

The timing circuit 62 supplies a sampling pulse to the sample and hold circuit 66 at the timing of one wobbled pit shown in FIG. 13, and supplies a sampling pulse to the sample and hold circuit 67 at the timing of the other wobbled pit. Accordingly, the sample and hold circuits 66 and 67 sample and hold the level of the RF signal at the timing of the two wobbled pits. The differential amplifier 69 subtracts the output of the sample and hold circuit 67 from the output of the sample and hold circuit 66, and generates a tracking error signal. This tracking error signal is output to the tracking actuator 70
And tracking control is performed. The input terminal of the differential amplifier 69 to which the outputs of the sample hold circuits 66 and 67 are supplied is switched by the switch 68 to the opposite side (opposite polarity side) between the odd track and the even track. Therefore, even when wobbled pits are shared by adjacent tracks, correct tracking servo is executed.

Although the present invention has been described with reference to the case where the present invention is applied to an optical disc, the present invention can be applied to other information recording media and recording / reproducing apparatuses therefor.

[0080]

According to the present invention, there is provided an information recording apparatus comprising:
According to the information recording method described in claim 7, the information pits
At least one of the rising edge and the falling edge
The position of the edge is two or more predetermined positions from the predetermined reference position.
To any position of
To represent multi-valued information,
Digital information can be recorded at a higher density.
It will work.

According to the information recording apparatus of the present invention,
The position of the rising edge of the information pit is
And two or more predetermined positions from the reference position of the rising edge.
Position by shifting it stepwise
1 to represent multi-valued information and the information pit
The position of the falling edge is determined according to the recorded information.
Any of two or more predetermined positions from the reference position
The second multi-value information is shifted to a position in a step-like manner.
To represent two multi-valued information in one information pit.
To record digital information at higher density.
Can be recorded.

According to the information recording apparatus of the third aspect,
Prescribed ratio for multiple information pits on information recording medium
The position of its rising or falling edge, located at
Record the position reference pit that represents the reference position.
Speed control of the information recording medium during recording
Can be

According to the information recording medium of the fourth aspect,
The information pit is located at its rising or falling edge.
At least one edge position corresponds to the multi-valued information.
Any of two or more predetermined positions from a fixed reference position
It is formed so that it changes stepwise
High-density information recording media.
You.

According to the information recording medium of the fifth aspect,
At a predetermined ratio for multiple information pits,
A position reference pit whose position represents a reference position is further formed.
The effect of jitter during playback
Implements an information recording medium that can read
Can be manifested.

According to the information recording medium of the sixth aspect,
Information pit phase is 90 degrees in adjacent track
Because it was shifted, the track pit was narrow,
First, to realize an information recording medium with less crosstalk
Can be.

An information reproducing apparatus according to claim 8 and a claim
According to the information reproducing method described in Item 11, the information pits
Edge of the detected information pit,
Any of two or more positions shifted stepwise from the reference position
Is determined, and based on the determination result, multi-valued
Since the corresponding value of the information is determined,
It is possible to accurately reproduce the information described in each time
Become.

According to the information reproducing apparatus of the ninth aspect,
The position of the edge of the detected information pit is stored in the stored position
Information pit corrected at the edge position of the quasi-pit and corrected
The edge position of the
The effect of jitter on the signal can be reduced.

[0088]

[0089]

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of information recording by the edge of an information pit according to the present invention.

FIG. 2 is a view for explaining an information recording format of one sector according to the present invention.

FIG. 3 is a view for explaining the principle of reading data from an edge position of an information pit according to the present invention;

FIG. 4 is a diagram for explaining the influence of variations in sensitivity of an optical disk;

FIG. 5 is a diagram illustrating the operation of a position reference pit according to the present invention.

FIG. 6 is a diagram for explaining an output state when correction is not performed using a position reference pit according to the present invention.

FIG. 7 is a diagram for explaining an output state when correction is performed using a position reference pit according to the present invention.

FIG. 8 is a diagram illustrating a state in which the phase of an information pit is shifted by 90 degrees between adjacent tracks according to the present invention.

FIG. 9 is a diagram illustrating a tracking state by three spots.

FIG. 10 is a view for explaining a tracking state by three spots when the track pitch is narrowed;

FIG. 11 is a view for explaining a tracking state by a wobbled pit.

FIG. 12 is a view for explaining a tracking state by wobbled pits when a track pitch is narrowed;

FIG. 13 is a view for explaining an arrangement of pits near a servo area of the optical disc of the present invention.

FIG. 14 is a diagram for explaining a difference between an information pit of the present invention and a pit in another information recording medium.

FIG. 15 is a block diagram showing a partial configuration of an embodiment of the information recording apparatus of the present invention.

FIG. 16 is a block diagram showing the configuration of another part of the embodiment of the information recording apparatus of the present invention.

FIG. 17 is a timing chart for explaining the operation of the embodiment in FIG. 16;

FIG. 18 is a block diagram showing the configuration of an embodiment of the information reproducing apparatus of the present invention.

FIG. 19 is a block diagram showing a configuration of an embodiment of a tracking servo device in the information recording / reproducing device of the present invention.

[Explanation of symbols]

 Reference Signs List 10 data selector 15 delay line 18 T-type flip-flop 31 PLL circuit 32 timing controller 33 sawtooth oscillator 35 binarization circuit 36, 37 A / D converter 39 to 41 latch circuit 45, 46 conversion map circuit 61 PLL circuit 62 timing Circuit 63 Sample hold circuit 64 Comparison circuit 65 Reference voltage generation circuit 66, 67 Sample hold circuit 69 Differential amplifier 70 Tracking actuator 80 Tracking servo circuit

Continuation of the front page (56) References JP-A-64-78471 (JP, A) JP-A-2-183471 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7 / 00-7/013

Claims (11)

(57) [Claims] 1. An information recording apparatus for recording digital information by forming information pits on an information recording medium, wherein the information pit has a small number of rising edges or falling edges.
At least one edge position from a predetermined reference position,
Stepwise at any of two or more predetermined positions
The multi-value information is represented by shifting the multi-value information.
A first recording unit for recording information;
Information recording device. 2. The information recording device according to claim 1, wherein said first recording means includes an information pit.
The position of the rising edge of the
Any of two or more predetermined positions from the reference position of the rising edge
The first multiple is shifted to some position in a step-like manner.
Value information as well as the information pits.
The position of the falling edge is determined by the falling
One of two or more predetermined positions from the reference position of the edge
To the second multi-valued information
Information, one information pit represents two
2. The information according to claim 1, wherein value information is recorded.
Information recording device. 3. The information recording medium according to claim 2 , wherein
The rise or
Is the position reference where the position of the falling edge represents the reference position.
Further comprising a second recording means for recording the pits.
The information recording device according to claim 1, wherein 4. Information pits corresponding to digital recording information
The information pit has a rising edge or a falling edge.
The position of at least one edge of the edge corresponds to the multi-valued information.
Any of two or more predetermined positions from the predetermined reference position
It is formed so that it changes stepwise in position
An information recording medium characterized by the above-mentioned. 5. A predetermined division for a plurality of said information pits.
The position of the edge is the position reference representing the reference position.
The pit is further formed.
4. The information recording medium according to 4. 6. The information recording medium has a constant angular velocity.
A information recording medium which is rotated as the phase of the information pits in the adjacent track 9
The information according to claim 4, wherein the information is shifted by 0 degrees.
recoding media. 7. An information pit is formed on an information recording medium.
Information recording device for recording digital information by
In the recording method, the number of rising edges or falling edges of the information pit is small.
At least one edge position from a predetermined reference position,
Stepwise at any of two or more predetermined positions
The multi-value information is represented by shifting the multi-value information.
Information characterized by including a recording step of recording information.
Information recording method. 8. A rising edge or a falling edge of an information pit.
The position of at least one of the edges is determined by a predetermined reference.
From the position to any one of two or more predetermined positions
The multi-value information is displayed by shifting
To reproduce the information recording medium on which the information pits are formed.
An information reproducing apparatus, wherein: an edge detecting means for detecting an edge of the information pit;
Edge position is shifted stepwise from the reference position
Determine which of two or more positions is located, and determine
Based on the result, a corresponding value of the multi-value information is obtained.
Information reproducing instrumentation, characterized in that it comprises a Mel determination means
Place. 9. The information recording medium includes a plurality of the information
The rising edge, which is arranged at a predetermined ratio to the pit,
Edge or falling edge represents the reference position
A position reference pit is recorded, and the edge detecting means detects the position of the position reference pit.
An edge representing the reference position is also detected, and the position reference pin detected by the edge detecting means is detected.
Storage means for storing the position of the edge of the bit, and the information pit detected by the edge detection means.
The position of the edge is stored in the position stored in the storage means.
Correction means for correcting at the position of the edge of the reference pit.
And the determination unit is configured to correct the information corrected by the correction unit.
請characterized in that determining the position of an edge of the multi-address pit
An information reproducing apparatus according to claim 8. 10. The edge detecting means according to claim 1 , wherein said correcting means comprises :
As the position of the edge of the information pit detected by
From the read value, before being stored in the storage means
Value read as the position of the edge of the position reference pit
Claim 9, characterized in that the correction by subtracting the
An information reproducing apparatus according to claim 1. 11. A rising edge or a falling edge of an information pit.
The position of at least one of the edges
From the sub-position to any one of two or more predetermined positions,
The multi-value information is represented by shifting in steps.
To reproduce the information recording medium on which the information pits are formed.
Detecting an edge of the information pit in the information reproducing method of the information reproducing apparatus.
And the information pin detected in the processing of the edge detecting step.
The position of the edge of the slot is stepped from the reference position.
Determine which of the two or more shifted positions is located,
Based on the determination result of
Determining a value.
Playback method.