JPH04366426A - Information recording medium and its recording/ reproduction device - Google Patents

Abstract

PURPOSE:To enable digital information to be recorded with a high density by recording the digital information while shifting a leading or trailing edge of an information bit in step shape from a specified reference position corresponding to the recorded information. CONSTITUTION:3 and 7 are expressed by leading and trailing edges of a first information bit after a position reference bit and 0 and 4 are expressed by the leading and trailing edges of the next information bit. Then, a PLL bi is recorded at the information recording medium at a certain period. At the time of recording of information, this PLL bit (clock bit) is reproduced and a reference clock is generated in synchronization with it. Then, a reference position of edge is determined in reference to this reference clock. Then, the leading edge and trailing edge positions of the information bit are shifted in step shape corresponding to a digital data to be recorded from the reference position which is indicated by the leading edge of the reference clock.

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 use in recording and reproducing information on, for example, an optical disc and a recording and reproducing apparatus thereof.

0002

2. Description of the Related Art In conventional optical discs, servo byte sections are periodically provided at predetermined positions on each track, and each servo byte section includes a clock pit for generating a reference clock and a wobbled pit for tracking. We are trying to form a A reference clock (channel clock) is generated in correspondence with the clock pit, and information is digitally recorded using pits whose length is an integral multiple of the period of the reference clock.

For example, in a compact disc, there is no clock pit, but the length is an integral multiple of the period of the reference clock (channel clock) (0.
Information is digitally recorded using pits (9 μm to 3.3 μm).

0004

[Problems to be Solved by the Invention] In this way, conventional optical discs and compact discs form pits with a length that is an integral multiple of the period of the reference clock (channel clock). Since information is recorded accordingly, there is a problem in that it is difficult to improve the recording density.

For example, if you try to record a 0.9 μm pit immediately after recording a 3.3 μm pit, the disk (recording master) will be damaged while the 3.3 μm pit is being recorded due to the so-called heat storage effect. 0.9 because it is warmed
The μm pits are formed larger than expected. As a result, the signal is distorted, and the reading margin of the digital signal becomes smaller.

[0006] The present invention has been made in view of this situation, and is intended to further improve the recording density.

[0007]

[Means for Solving the Problems] The information recording device according to claim 1 is characterized in that the position of a rising or falling edge of an information pit is determined by, for example, the rising or falling edge of a reference clock, or the position of a rising or falling edge of a position reference pit. A major feature is that information is recorded in a manner that is shifted in steps corresponding to digitally recorded information from a reference position represented by a falling edge or the like.

[0008] The information recording medium according to claim 2 is basically characterized in that it includes information pits formed so that the edge positions change in accordance with the information.

The information recording medium according to the third aspect is characterized in that the phases of the information pits in adjacent tracks are shifted by 90 degrees.

An information reproducing apparatus according to a fourth aspect of the present invention is characterized in that information is reproduced by detecting a deviation of a rising edge or a falling edge of an information pit from a reference position.

In the embodiment, the reference position is detected by the A/D converters 36, 37 and the latch circuits 40, 42, and the deviation from the reference position is detected by the A/D converters 36, 37.
7. Detected by latch circuits 39 and 41 and subtracters 43 and 44.

The information recording apparatus according to the present invention is characterized in that a position reference pit representing a reference position of an edge of an information pit is recorded.

[0013] The information recording medium according to claim 6 is characterized in that position reference pits representing reference positions of edges of information pits are provided at a predetermined ratio to the information pits.

An information reproducing apparatus according to a seventh aspect of the present invention is characterized in that the correction means corrects the detected position of the edge of the information pit by the detected position of the edge of the position reference pit.

In the embodiment, the edge position of the information pit is determined by the A/D converters 36, 37, the latch circuit 39,
The edge reference position is detected by A/D converters 36, 37 and latch circuits 40, 42, and correction is performed by subtracters 43, 44.

An information recording medium according to an eighth aspect of the present invention is characterized in that wobbled pits for tracking are arranged so as to be shared by adjacent tracks.

The information recording and reproducing apparatus according to the present invention is characterized in that the polarity of tracking by wobbled pits is switched between odd-numbered tracks and even-numbered tracks.

In this embodiment, a sample and hold circuit 63, a comparison circuit 64 and a reference voltage generation circuit 65 detect whether the track is an odd numbered track or an even numbered track. The tracking servo means is constituted by a tracking servo circuit 80.

An information recording apparatus according to a tenth aspect of the present invention is characterized in that information pits are recorded with a phase shift of 90 degrees in adjacent tracks.

[0020]

In the information recording apparatus according to claim 1, the position of the rising or falling edge of the information pit is determined by the position of the rising or falling edge of the reference clock, or the position of the rising or falling edge of the information pit.
Information is recorded by shifting stepwise from the position of the rising or falling edge of the position reference pit in accordance with the digitally recorded information. Therefore, it becomes possible to record digital information with higher density.

In the information recording medium according to the second aspect of the present invention, the information pits are formed such that the edge position changes in accordance with the information. Therefore, a higher density recording medium can be realized.

In the information recording medium according to claim 3, the phase of the information pits is 90° in adjacent tracks.
It is shifted by a degree. Therefore, even when the track pitch is narrowed, an information recording medium with less crosstalk can be realized.

In the information reproducing apparatus according to the fourth aspect of the present invention, a deviation of the position of a rising edge or a falling edge of an information pit from a reference position is detected. Therefore, digital information recorded at high density can be accurately reproduced.

In the information recording apparatus according to the fifth aspect of the present invention, position reference pits representing reference positions of edges of information pits are recorded. Therefore, even if the speed control of the information recording medium during recording is simplified, information can be recorded reliably.

In the information recording medium according to the sixth aspect of the present invention, position reference pits representing reference positions of edges of information pits are formed at a predetermined ratio with respect to the information pits. Therefore, it is possible to realize an information recording medium that is less affected by jitter during reproduction and allows accurate information reading.

In the information reproducing apparatus according to the seventh aspect, the detected position of the edge of the information pit is corrected by the detected position of the edge of the position reference pit. Therefore, it is possible to reduce the influence of jitter during reproduction and to read information accurately.

In the information recording medium according to the eighth aspect of the present invention, wobbled pits for tracking are arranged so as to be shared by adjacent tracks. Therefore, it becomes possible to further narrow the track pitch.

In the information recording and reproducing apparatus according to the present invention, the polarity of tracking by wobbled pits is switched between odd-numbered tracks and even-numbered tracks. Therefore, accurate tracking is possible even when wobbled pits are shared between adjacent tracks.

In the information recording apparatus according to the tenth aspect of the invention, the information pits are formed in adjacent tracks with a phase shift of 90 degrees. Therefore, since crosstalk can be reduced, information can be recorded with a narrower track pitch.

[0030]

Embodiment Next, an embodiment of an information recording medium and a recording/reproducing apparatus thereof according to the present invention will be described. FIG. 1 represents the recording principle of the invention. As shown in the figure, in the present invention, the position of at least one (both in the embodiment) of the rising and falling edges of the information pit is
The edge position is shifted in steps from the reference edge position in accordance with the digitally recorded information. That is, the edge position (zero cross position) of the recording signal shown in FIG. 1B is delayed in steps by a predetermined time corresponding to the recording information, with the rising edge position of the reference clock shown in FIG. 1C as the reference position. or advanced. In the embodiment, since the edge position is delayed, the position of the edge is moved from the reference position to the right side in the figure, but when it is advanced in time, it is moved to the left side in the figure. Assuming that each edge represents, for example, 3 bits of digital data (i.e. 0 to 7), each edge is formed at the reference position when the data is 0, and delayed by a unit time (1 step) when the data is 1. 2
When , it is delayed by twice the unit time (2 steps), and 3
When , the delay is delayed by three times the unit time (three steps). 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 the information recording medium, such as an optical disk, as shown in FIG. 1A. Note that this information pit can be formed as a physical concavity or convexity, or it can be formed by setting the properties of the information recording medium (for example, reflectance or transmittance) to a different value from other parts. good. In the example, 3 and 7 are represented by the rising edge and falling edge of the first information pit following the position reference pit (this position reference pit will be described in detail later), and the rising edge and falling edge of the next information pit 0 and 4 are represented by edges and falling edges. If the length on the recording medium corresponding to the unit time (one step) of the recording signal delay is, for example, 0.05 μm, each edge is 3×0.05 μm, 7×0.05 μm, 0 from the reference position. ×
It is moved to the right in the figure by 0.05 μm, 4×0.05 μm. Further, the length on the optical disc corresponding to one cycle of the reference clock (the length when both the rising edge and the falling edge are not delayed) is set to 1.2 μm.

As described above, in order to shift the edge of the information pit from the reference position in accordance with the digitally recorded information, it is necessary to clarify the reference position of the edge. Therefore, as shown in FIG. 2, information recording media have PLL pits (clock pits) at regular intervals (for example, one
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 recording information, this PLL pit (clock pit) is reproduced, and a reference clock (FIG. 1C) is generated in synchronization with this. Then, the reference position of the edge is determined based on this reference clock (in the embodiment shown in FIG. 1, the rising edge of the reference clock is used as 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. During playback, the optical disc on which information is recorded as shown in FIGS. 1 and 2 is played back, and an RF signal as shown in FIG. 3A is obtained. 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 this binary RF signal, and a reference clock as shown in FIG. 3C is generated in synchronization with this component. Further, in synchronization with this reference clock, a sawtooth wave signal (or a triangular wave signal may be used) as shown in FIG. 3D is generated.

This sawtooth wave signal reaches its maximum level (255) just before the falling edge of the reference clock, and
After falling, it rapidly drops to the lowest level (0) and then linearly increases again to the maximum value, so the level of 256 steps can be determined using this sawtooth wave signal. Therefore, the binarized RF signal (Fig. 3B
) at the timing of the rising edge and falling edge of the sawtooth wave signal (Fig. 3D) (edge shift of the information pit) is detected, and also the level of the reference clock (Fig. 3C) is detected.
Detects the level of the sawtooth signal (Figure 3D) at the rising edge of the information pit (reference position of the edge of the information pit), and detects the deviation of the edge of the information pit from the reference position (i.e., recorded data) from the difference between the two. can do.

By the way, if there are variations in the sensitivity of the optical disc or temporal variations in the recording laser power, variations will occur in the pits formed. FIG. 4 shows this situation. That is, when a recording laser beam of the same level (intensity) is irradiated, if the sensitivity of the optical disc is low, the length of the formed pit will be shorter than if the sensitivity is high. Furthermore, even if the sensitivity is constant, similar variations occur when the power of the recording laser beam changes.

[0036] Such variations make it difficult to form the above-mentioned edges at accurate positions, that is, to record accurate information. Therefore, in this embodiment, in addition to the reference pits (PLL pits), position reference pits are also recorded at regular intervals. In this embodiment, one position reference pit (that is, one in each sector) is formed immediately after the clock pit, and a plurality of information pits are formed after that. Both the rising edge and the falling edge of this position reference pit are always located at the reference position (the position of the rising edge of the reference clock).

Next, the function of this position reference pit will be explained with reference to FIG. In this example, FIG.
As shown in A, since the first pit is the position reference pit, the data corresponding to both edges thereof are 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, and 1 and 0.
Each piece of data corresponds to each other. Therefore, assuming that the optical disc has appropriate sensitivity, Fig.
Position reference pits and information pits as shown in FIG. 5C are formed on the optical disc in response to recording signals (recording pulses) as shown in FIG.

During reproduction, when the rising and falling edges of each pit are detected and 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 as follows. Assuming that all of them are 64, by detecting the rising and falling edges of the three information pits and detecting the level of the sawtooth wave signal at the detection timing, as shown in FIG. 5E, 82 and 64, respectively, are detected. 76 and 94, 70 and 64
become. To find the deviation of each value from the reference position,
As described above, it is sufficient to read the level of the sawtooth wave signal at the rising edge of the reference clock in each pit and subtract that value. Incidentally, the level of the sawtooth wave signal at the edge timing of this reference clock is the same as the level of the position reference pit. Therefore, instead of reading the level of the sawtooth wave signal corresponding to the edge of the reference clock for each pit, the level of the sawtooth wave signal at the rising and falling edges of this position reference pit is read as follows:
It can be used as the level of the sawtooth wave signal corresponding to the edge of the reference clock for each pit (this is where the position reference pit has a second effect in addition to the sensitivity correction effect (first effect) described later). ).

For this example, the values shown in FIG. 5E, 8
By subtracting the values 64 and 64 at the position reference pit from 2 and 64, 76 and 94, and 70 and 64,
As shown in , the values corresponding to the amount of deviation are, respectively,
You can get 18 and 0, 12 and 30, 6 and 0. Since the value 6 of this deviation corresponds to the unit delay time mentioned above, the data can be obtained by dividing these values by 6, respectively, as 3 and 0, 2 and 5, and 1 and 0. . These values are the same as the original data shown in FIG. 5A.

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

For example, as shown in FIG. 5I, if the position of the rising edge in the position reference pit is reduced by 10 from the original reference position in terms of the level of the sawtooth signal (FIG. 5H), The position of the falling edge also increases by 10 from the original reference position in terms of the level of the sawtooth signal, and becomes 54 (=64-10) and 74 (=
64+10). Similarly, at the rising edge and falling edge of each information pit, the level of the sawtooth signal becomes smaller or larger by 10 compared to the original recording position. That is, each information pit (Fig.
The values of the sawtooth signal (Fig. 5H) at the timing of the rising edge and falling edge of G) are as shown in Fig. 5H, respectively.
As shown in I, 72 (=82-10) and 74 (=64
+10), 66 (=76-10) and 104 (=94+1
0), 60 (=70-10) and 74 (=64+10).

Therefore, the values 72 and 7 of these information pits
4, 66 and 104, 60 and 74 to standard pit value 54
and 74, as shown in Figure 5J, we get 18 and 0,
12 and 30, 6 and 0 are obtained. These values are shown in Figure 5F
This is the same as in the case of appropriate sensitivity shown in (this is the first effect of the position reference pit).

[0043] In the above, the case where the sensitivity is too high has been explained as an example, but if the sensitivity is too low, the edge of the information pit will be shortened by the same length as the edge of the position reference pit, so the sensitivity will be reduced. As with too high, the same data can be obtained as with proper sensitivity.

That is, by forming the position reference pits in this manner, it is not only unnecessary to read the sawtooth wave signal every reference clock of each pit, but also it is possible to read the sawtooth wave signal correctly even if there are variations in sensitivity, etc. It becomes possible to record and reproduce data.

FIGS. 6 and 7 illustrate the effect of correction using position reference pits. Both of these figures
The horizontal axis represents time and the vertical axis represents voltage. The voltage on the vertical axis is expressed by converting the data from 0 to 7 described in FIG. 1 into voltage. In other words, if the deviation of the edge obtained at a certain time (predetermined position on the horizontal axis) from the reference position (this deviation is between 0 and 7 as described above) is 0, then the edge is 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 that are reproduced one after another in this way is expressed as a predetermined voltage point (by monitoring the output of the D/A converter 47 in FIG. 18, which will be described later). (A waveform like this is obtained.)

FIG. 6 shows a state in which no correction is made using the position reference pit. In the case of this figure, for each data 0 to 7, the points that should originally be aligned on the horizontal line indicating a constant voltage are significantly shifted in the vertical axis direction. For example, even if an edge represents the same data 5, the deviation from the reference position may become large (for example, the deviation amount (voltage) originally represents data 7) or become small (for example, the deviation amount (voltage) originally represents data 7). This means that the amount of deviation (voltage) is changing, or the deviation is changing. In order to read (identify) which data from 0 to 7 it is, one data (for example, 5
) and the voltage (deviation amount) representing adjacent data (for example, 6) as a threshold value, it is necessary to determine whether the voltage is larger or smaller than the threshold value. However, as shown in FIG. 6, if the voltage representing each data fluctuates, it is difficult to read (identify) the data (5 or 6) based on a fixed predetermined threshold voltage. I won't be able to do it.

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

FIG. 8 shows pits (
(position reference pit and information pit). In the case of a CAV (constant rotational angular velocity) disc, as shown in the figure, the pit phase (phase when data is 0) of adjacent tracks (odd-numbered tracks and even-numbered tracks) is 90 degrees. be shifted. In other words, the phase of the recording signal when the data is 0 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 with respect to the phase of the reference clock of the even-numbered track. In this way, when the edge of one position reference pit or information pit of one track is being reproduced with one optical spot, the edges of adjacent tracks will not be located within that optical spot, so cross There will be less talk. Therefore, it is possible to narrow the track pitch and achieve higher density.

Next, the tracking method will be explained. 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) originally used for reproducing information, two sub-beams (spots) are arranged on both sides of the main beam (spot). By placing the sub-beams on the left and right edges with respect to the direction of travel of the truck, 2
A photodetector detects the reflected light from the two sub-beams, and a tracking error signal can be obtained from the difference in output. However, as shown in FIG.
If the track pitch is narrowed, the sub-beams will read information from adjacent tracks, making it impossible to generate a tracking error signal.

Furthermore, some optical discs 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 in level between the reproduction signals of these two wobbled pits. However, when the track pitch is narrowed in this method as well, as shown in FIG. 12, wobbled pits for adjacent tracks interfere with each other, making it impossible to generate a correct tracking error signal.

Therefore, in this embodiment, the sample servo method shown in FIG. 11 is basically adopted, but as shown in FIG. 13, one clock is placed in the servo area on the center line of the track. A pit (PLL pit) and two wobbled pits are arranged so as to be offset to the left and right with respect to the center line of the track, and also to be offset in the track direction (so as to face each other with a clock pit in between). These pits are pre-recorded as pre-pits, for example as physical irregularities, before recording the original information (
It is formed. Then, 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 tracks, and one wobbled pit is used for both left and right tracking. By doing so, the track pitch can be narrowed and a tracking error signal can be generated.

However, in this way, when one wobbled pit is shared between left and right tracks, it is necessary to reverse the polarity of the tracking servo between odd and even tracks. An example in this case will be described later with reference to FIG.

When the positions of the position reference pits and the information pits are shifted by 90 degrees between odd and even tracks, for example, one of the even and odd tracks (in the case of the embodiment, even truck)
The position of the last information pit in the other track (
In the case of the embodiment, it is shifted to the rear of the last information pit of the odd-numbered track. That is, when observed on the time axis (on the reproduced signal), the last information pit appears later in even-numbered tracks than in odd-numbered tracks. Alternatively, focusing on the position reference pit placed immediately after the clock pit, the position reference pit appears later on even-numbered tracks than on odd-numbered tracks. Therefore, by detecting the timing of occurrence of this last information pit or position reference pit, it is possible to determine whether the track is an odd track or an even track. 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 according to the present invention will be compared with reference to FIG. In a conventional sample servo optical disc, a reference clock (channel clock) is generated in synchronization with a clock pit, as shown in FIG. 14A. Then, a pit having a length that is an integral multiple of the period of the reference clock is formed. The length of the pit to be formed is determined by the recording information.

Furthermore, although clock pits are not formed in compact discs, as shown in FIG. 14B, pits whose length is an integral multiple of the period of the reference clock (channel clock) are formed as one unit. be done.

On the other hand, in the embodiment of the present invention,
As shown in FIG. 14C, the reference clock is generated in synchronization with the clock pit (PLL pit).
This is the same as in . However, the length of the information pit is basically the length of the period of the reference clock (in this case, the position of the edge is taken as the reference position), and the length (position of the edge) changes depending on the recorded data. However, what is meaningful as information is the amount of deviation of the edge from the reference position. Therefore, in this embodiment, the length of the information pit is set within a range of one to two times the period of the reference clock.

As is clear from comparing FIG. 14C with FIGS. 14A and 14B, according to this embodiment, higher density information recording is possible. In order to determine a more accurate reference position, position reference pits are inserted in addition to clock pits as necessary.

In the case of a compact disc, the track pitch is 1.6 μm, and the recording density is 0.6 μm per bit.
It is. In contrast, in this embodiment, the track pitch is 1.2 μm, and the recording density is 0.4 per bit.
It was possible to make it μm. This means that the recording density is twice that of compact discs.

Next, an embodiment of an apparatus for realizing the above-mentioned recording and reproduction will be described. FIG. 15 shows the configuration of a part of the recording device. The data output circuit 51 A/D converts a signal supplied from a circuit (not shown), performs predetermined processing, and then outputs the signal to an error correction (ECC) circuit 52. The error correction circuit 52 performs processing such as adding an error detection and correction code and interleaving 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 data is shown in Figure 1.
6 is supplied to the recording device shown in FIG.

Terminal 11 in FIG. 16 is connected to the reference clock (FIG.
7A) is supplied. This reference clock is generated, for example, by a PLL circuit 31 in FIG. 18, which will be described later, in synchronization with the clock pits of the optical disc. This reference clock is supplied to delay line 15 via buffer 12 and switch 14. The switch 14 is switched to the contact a side for odd-numbered tracks, and to the contact b side for even-numbered tracks. When 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
It is grounded via 6.

The delay line 15 has eight output terminals each having a corresponding buffer 17, and each output has a different delay time for each unit time. In other words, this unit time is
0.05 μm on an optical disk, as explained in
is set to a time corresponding to the length of That is, each output terminal outputs a reference clock that is delayed by a time from 0 times the unit time to 7 times the unit time. The data selector 10 includes a data length conversion circuit 53
One of these eight output terminals is selected in accordance with the 3-bit data supplied by the terminal. In other words, when the data is 0, select the output terminal with a delay time of unit time x 0 (that is, output the reference clock without delay), and when the data is 5, select the output terminal with a delay time of unit time x 5. do. As a result, the reference clock is delayed stepwise by the time corresponding to the digital data, with each unit time being one step. When recording position reference pits, 0 is the data selector 1.
It is input to 0. Therefore, a reference clock without delay 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 its output is inverted every time it is triggered. The output of this T-type flip-flop 18 is supplied to one input of an AND gate 20.

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

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

Next, the playback device will be explained 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. P.L.
The L circuit 31 extracts a component due to the above-mentioned clock pit (PLL pit) from the RF signal (FIG. 3A), generates a reference clock (FIG. 3C), and supplies it to the sawtooth wave oscillator 33. The sawtooth wave oscillator 33 generates a sawtooth wave signal (FIG. 3D) in synchronization with the input reference clock and outputs it to the A/D converters 36 and 37. Further, the reference clock generated by the PLL circuit 31 is also supplied to the timing controller 32, and the timing controller 32 synchronizes with the reference clock and outputs a latch pulse to the latch circuit at the timing of the rising edge of the position reference pit (FIG. 3A) described above. 40
At the same time, 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 predetermined frequency and phase characteristics, and then converts the input RF signal to the binarization circuit 3.
Output to 5. The binarization circuit 35 binarizes the input RF signal. This binary 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 signal is input to the clock terminal of the A/D converter 37 and the latch circuit 39. It is supplied to the clock terminal of circuit 41.

Therefore, in the A/D converter 36, the level of the sawtooth wave signal (FIG. 3D) at the timing of the rising edge of the binarized RF signal is sampled.
The sample value is A/D converted. As described above, since the level of the sawtooth signal is decomposed into 256 steps, 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. Further, 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 by the timing controller 32.

In this way, the data of the rising edge of the position reference pit explained in FIG. 5E (data of the reference position)
64, or the rising edge data (reference position data) 54 of the position reference pit explained with reference to FIG. 5I is latched into the latch circuit 40. Further, the data 82, 76, 70 of the rising edge of the information pit explained in FIG. 5E (data shifted from the reference position), or the data of the rising edge of the information pit explained in FIG. 5I (data shifted from the reference position) 72, 66, and 60 are latched by the latch circuit 39. The subtracter 43 subtracts the latch data of the latch circuit 40 from the latch data of the latch circuit 39. As a result, the values 18, 12, and 6 representing the deviation from the reference position of the rising edge of the information pit explained in FIG. 5F, or the deviation from the reference position of the rising edge of the information pit explained in FIG. The values 18, 12, and 6 are obtained.

The 8-bit data output from the subtracter 43 is converted into 3-bit data by the conversion map circuit 45 and output. In addition, when the output of the subtracter 43 is D/A converted by the D/A converter 47 and monitored, the result is as shown in FIG.
) can be observed as described above.

On the other hand, in the A/D converter 37,
The level of the sawtooth wave signal at the timing of the falling edge of the binary RF signal is sampled, and the sample value is A/D converted. This sample value is output to 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. Further, 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 by the timing controller 32.

In this way, the data of the falling edge of the position reference pit explained in FIG. 5E (data of the reference position)
64 or the falling edge data (reference position data) 74 of the position reference pit described in FIG. 5I is latched by the latch circuit 42. In addition, data 64, 94, 64 of the falling edge of the information pit explained in FIG. 5E (data shifted from the reference position), or data of the falling edge of the information pit (data shifted from the reference position) explained in FIG. Data) 74, 104, 74 are latched by the latch circuit 41. The subtracter 44 subtracts the latch data of the latch circuit 42 from the latch data of the latch circuit 41. As a result, the value 0, 30, 0 representing the deviation from the reference position of the falling edge of the information pit explained in FIG. 5F, or the deviation from the reference position of the falling edge of the information pit explained in FIG. 5J, In addition, corrected values 0, 30, 0 are obtained.

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

Although two A/D converters are used in the above, the signals supplied from the binarization circuit 35 or the inverter 38 are alternately switched and supplied to the clock terminals of the A/D converters. It can also be made into pieces. Also, a sample and hold circuit can be used instead of the A/D converter. Furthermore, a counting clock with a frequency sufficiently higher than the reference clock is generated at a predetermined period in synchronization with the reference clock, and this is counted by a counter, and the count value is used as the rising edge or rising edge of the binary RF signal. Edge deviation can also be detected by latching at the timing of the falling edge.

Furthermore, in the above, the latch circuits 40 and 42 independently latch the data of the position reference pit for each sector and use it for correction, but the average value of the values in a plurality of sectors is calculated. This can also be used for correction. In this way, reliability can be further improved.

FIG. 19 shows an optical disc 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. shows an example of a configuration in which odd-numbered tracks and even-numbered tracks are determined and the polarity of the tracking servo is switched in accordance with the determination result. In this embodiment, the reproduced RF signal reproduced and output from the optical disc is transmitted to the PLL circuit 6.
1 and is supplied to the sample and hold circuit 63. P.L.
The L circuit 61 generates a reference clock from components corresponding to the reference pits 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 sample and hold circuits 63, 66, and 67.

As already explained with reference to FIG. 13, when the pit phases are shifted by 90 degrees, the timing at which the last information pit (or position reference pit) occurs differs between odd-numbered tracks and even-numbered tracks. The timing circuit 62 outputs a sampling pulse to the sample hold circuit 63 at a timing T (see FIG. 13) at which the last information pit exists in even-numbered tracks and the last information pit does not exist in odd-numbered tracks. In even-numbered tracks, since information pits exist, the level of the RF signal at the timing when the sampling pulse is input is low. On the other hand, since there are no information pits in odd-numbered tracks, the level of the RF signal is higher than that in even-numbered tracks.

Therefore, the level of the RF signal at the timing when the sampling pulse is input is sampled and held in the sample and hold circuit 63, and this sample and hold value is used in the comparison circuit 64 and the level of the RF signal at the timing when the sampling pulse is inputted.
Compare with the reference voltage output by This reference voltage is set to an intermediate value between the sample and hold values in odd-numbered tracks and the sample-and-hold values in even-numbered tracks. Therefore, the output of the comparison circuit 64 is at a high level when the track is an odd number, and is at a low level when the track is an even number. This output is used to switch the switch 14 in FIG. 16, and is also used to switch 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. Therefore, 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. A differential amplifier 69 subtracts the output of the sample and hold circuit 67 from the output of the sample and hold circuit 66 to generate a tracking error signal. This tracking error signal is transmitted to the tracking actuator 70.
tracking control is performed. The input terminals of the differential amplifier 69 to which the outputs of the sample and hold circuits 66 and 67 are supplied are switched to the opposite side (reverse polarity side) for odd-numbered tracks and even-numbered tracks by a switch 68. Therefore, correct tracking servo is executed even when the wobbled pit is shared between adjacent tracks.

Although the present invention has been described above using an example of applying the present invention to an optical disc, the present invention can be applied to other information recording media and recording/reproducing devices thereof.

[0080]

According to the information recording device according to claim 1, digital information is recorded by shifting the edge position of the information pit in steps from the reference position in accordance with the recorded information. Therefore, it becomes possible to record digital information with higher density.

According to the information recording medium according to claim 2,
Since the information pits are formed so that the position of the edge changes stepwise in accordance with the recorded information, an information recording medium with higher recording density can be realized.

According to the information recording medium according to claim 3,
Since the phase of the information pits is shifted by 90 degrees on adjacent tracks, the track pitch is narrow and
An information recording medium with less crosstalk can be realized.

According to the information reproducing device according to claim 4,
Since the deviation of the edge of the information pit from the reference position is detected, digital information recorded at high density can be accurately reproduced.

According to the information recording device according to claim 5,
Since the position reference pit representing the reference position of the edge of the information pit is recorded, it becomes possible to easily control the speed of the information recording medium during recording.

According to the information recording medium according to claim 6,
Position reference pits representing the reference positions of the edges of information pits are arranged at a predetermined ratio to the information pits, making it possible to create an information recording medium that is less affected by jitter during playback and allows accurate information reading. It can be realized.

According to the information reproducing device according to claim 7,
Since the detected position of the edge of the information pit is corrected by the detected position of the edge of the reference pit, the influence of jitter during reproduction can be reduced and the information can be read accurately.

According to the information recording medium according to claim 8,
Since the wobbled pits for tracking are arranged so as to be shared by adjacent tracks, the track pitch can be made narrower.

According to the information recording and reproducing apparatus according to the ninth aspect, since the polarity of tracking by wobbled pits is switched between odd-numbered tracks and even-numbered tracks, even when the track pitch is narrow, Accurate tracking becomes possible.

According to the information recording apparatus according to the tenth aspect, since the phases of the information pits in adjacent tracks are shifted by 90 degrees, information can be recorded with a narrow track pitch.

[Brief explanation of drawings]

[Fig. 1] A diagram explaining the principle of information recording using edges of information pits according to the present invention.

[Fig. 2] A diagram explaining the information recording format of one sector of the present invention.

[Fig. 3] A diagram explaining the principle of reading data from the edge position of an information pit according to the present invention.

[Figure 4] Diagram explaining the influence of variations in sensitivity of optical discs

FIG. 5 is a diagram explaining the action of the position reference pit of the present invention.

[
FIG. 6 is a diagram explaining the output state when no correction is performed using the position reference pit of the present invention

FIG. 7 is a diagram illustrating the output state when correction is performed using the position reference pit of the present invention.

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

[Figure 9] 3
Diagram explaining the tracking state by spot

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

[Figure 11]
Diagram explaining the tracking state by wobbled pits

FIG. 12 is a diagram explaining the tracking state due to wobbled pits when the track pitch is narrowed.

FIG. 13 is a diagram illustrating the arrangement of pits near the servo area of the optical disc of the present invention.

FIG. 14 is a diagram explaining the difference between the information pits of the present invention and pits in other information recording media.

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

FIG. 16 is a block diagram showing the configuration of other parts of an embodiment of the information recording device of the present invention.

FIG. 17 is a timing chart 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 device of the present invention.

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

[Explanation of symbols]

10 Data selector 15 Delay line 18 T-type flip-flop 31 PLL circuit 32 Timing controller 33 Sawtooth wave 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 and 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

Claims (10)

[Claims] Claim 1. An information recording device that records digital information by forming information pits on an information recording medium, wherein the position of a rising or falling edge of the information pit is adjusted from a predetermined reference position corresponding to the recorded information. An information recording device comprising means for recording digital information in a stepwise manner. 2. In an information recording medium having information pits corresponding to digitally recorded information, the information pits include:
An information recording medium characterized in that the edge position is formed so as to change stepwise from a predetermined reference position in accordance with digital information. 3. The information recording medium is an information recording medium that is rotated at a constant angular velocity, and the information pits are out of phase by 90 degrees in adjacent tracks. 2. The information recording medium according to 2. 4. From a reproduction signal of an information recording medium having information pits formed such that the edge position changes stepwise from a predetermined reference position in accordance with digital information, a reference value for the edge of the information pit is determined. An information reproducing apparatus comprising: a reference edge detection means for detecting a position; and an edge detection means for detecting a deviation of an edge of the information pit from a reference position. 5. Means for recording information pits on an information recording medium such that the edge position changes in accordance with recorded information, and a position reference pit whose edge position represents a reference position of the edge of the information pit. An information recording device comprising: a means for recording. 6. Information pits formed such that the edge positions change in accordance with recorded information; and information pits arranged at a predetermined ratio with respect to a plurality of information pits, the edge positions of which are formed to change in accordance with recorded information. An information recording medium comprising a position reference pit representing a reference position of an edge. 7. Information pits formed such that the position of the edge changes in accordance with the recorded information, and information pits arranged at a predetermined ratio with respect to a plurality of the information pits, the position of the edge of which changes according to the information pits. In an information reproducing apparatus for reproducing an information recording medium having a position reference pit representing a reference position of an edge, a reference edge detection means detects a position of an edge of the position reference pit, and a reference edge detection means detects a position of an edge of the information pit. Information edge detection means; and correction means for correcting the position of the edge of the information pit detected by the information edge detection means with the position of the edge of the reference pit detected by the reference edge detection means. Information reproducing device. 8. An information recording medium that records or reproduces information while rotating at a constant angular velocity, wherein wobbles for tracking are provided at positions offset toward the outer circumference and toward the inner circumference from the center of the track. An information recording medium characterized in that pits are arranged and the wobbled pits are arranged so as to be shared by adjacent tracks. 9. Wobbled pits for tracking are arranged at positions offset toward the outer circumference and toward the inner circumference from the center of the track, and the wobbled pits are shared by adjacent tracks. An information recording and reproducing device that records and reproduces information while rotating an arranged information recording medium at a constant angular velocity, and detects whether the track is an odd numbered track or an even numbered track. What is claimed is: 1. An information recording and reproducing apparatus comprising: a track detecting means for detecting a track; and a tracking servo means for switching the polarity of tracking by the wobbled pit in response to an output of the track detecting means. 10. In an information recording device that records information on an information recording medium while rotating at a constant angular velocity, means for recording digital information such that the edge position of an information pit is shifted in accordance with the recorded information. and means for recording the information pits so that the phases of the information pits are shifted by 90 degrees in adjacent tracks.