JPH04228112A - Information recording and reproducing method and its device - Google Patents

Abstract

PURPOSE:To increase the density of the storage information of an optical disk. CONSTITUTION:At the time of recording, continuous storage information 901 is segmented into 8(4X2) units, which are encoded into two-dimensional array of 4 columns by 2 rows (902), and then transformed to one-dimensional information array of 1 row each from 4 columns by 2 rows and read out (903). Based on this one-dimensional information array, a laser 905 is modulated (904), the laser beam is converged at a prescribed position through an optical system 906, and the 2 rows of bits 908,909 are formed on the disk face. At the time of reproducing, the laser beam from the laser 905 is condensed into bit through the optical system 906, a reflected light from the bit is received by an optical receiver 910 photoelectrically converted (911) and one-dimensional array signals are detected from the photoelectrically converted signals (912). From these array signals, two-dimensional codes are obtained, which are decoded and the continuous information is reproduced (914).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information processing device, and more particularly to an information recording and reproducing device and method for optical discs and the like.

0002

[Prior Art] Ever since the basic recording and reproducing method was proposed for conventional optical disks, up to today's practical stage, optical disks have been constructed using concentric tracks, similar to recording devices based on the magnetic recording principle. Data is recorded in time series along the circumferential direction, and the spacing between adjacent tracks is set to eliminate data interference (referred to as crosstalk) between adjacent tracks. There is no correlation.

[0003] As a technique for increasing the recording density of optical discs, there is, for example, Japanese Patent Laid-Open No. 2-53223.

0004

[Problems to be Solved by the Invention] Information recording and reproducing devices are always required to have higher density. To this end, in conventional magnetic recording, the measure to improve the recording surface density is to independently improve the track spacing and the bit density in the circumferential direction, and a similar approach has been taken for optical disks.

In conventional magnetic recording heads, the resolution in the circumferential direction and the radial direction are asymmetrical, so that the track density and the bit density differ by about one order of magnitude. However, in optical discs, the spots used for recording and reproducing are isotropic, and therefore, in optical discs for recording and reproducing data, the track density and the linear density are almost equal. However, even if the optical spot shape is isotropically reduced in order to improve the density, the linear density can be improved, but the track spacing cannot be improved to the same extent as the linear density. This is because there are many factors that cause spot position fluctuations in the radial direction, so the amount of fluctuation is large, and it is difficult to narrow the track interval.

[0006]

[Means for Solving the Problems] For the above purpose, the optical disc described above takes advantage of the isotropy of the spot, which is superior to conventional recording devices.

In order to achieve the above object of the information recording and reproducing apparatus of the present invention, there is provided a buffer means for storing continuous storage data in units converted into two dimensions; converting means into a data array of m columns;
a recording device that reads data in dimensional data strings and controls the m light sources according to these data strings; and an optical device that converges light beams from the m light sources to form m spots on the disk surface. The recorded data is recorded on the disk surface as a group of optically identifiable information identifiers having a two-dimensional spread of n×m.

[0008] Furthermore, the information recording/reproducing apparatus of the present invention converts continuous data into data having a two-dimensional spread of n×m, and records this on an optical disc as a group of optically distinguishable pits. An information recording/reproducing apparatus for reproducing data stored by a storage method, comprising: m light sources; an optical means for converging light beams from the m light sources to form m spots on a disk surface; m spots,
a positioning means for positioning the pit group on the disk surface; m detection means for detecting reflected light from the pit group corresponding to each spot; m columns from the reflected light detected by each detection means; generating means for generating a one-dimensional data string and combining n pieces of this data to generate n×m two-dimensional data; demodulating means for demodulating continuous data from the n×m two-dimensional data; Consisting of

The information recording and reproducing method of the present invention includes the following steps: encoding recorded information in two dimensions; converting this into a one-dimensional information array; and modulating a plurality of laser light sources using this information array. and recording a two-dimensional code on the disk surface;
a step of reproducing the dimensional information; a step of photoelectrically converting the reproduced signal; a step of detecting a one-dimensional array signal from the photoelectrically converted signal;
and decoding the dimensional information.

The information recording and reproducing method of the present invention further includes the steps of storing continuous recorded data in units that are converted into two-dimensional data; and encoding into an n×m two-dimensional data array corresponding to the data in the units. step; reading out the n×m two-dimensional data array by dividing it into m one-dimensional data strings, and controlling m light sources according to these data strings; and controlling the light fluxes from the m light sources. converging to form m spots on the disk surface; and recording data to be recorded as a group of optically distinguishable pits having a two-dimensional spread of n×m on the disk surface. ; positioning the m spots on the pit group on the disk surface; a detection step of detecting reflected light from the pit group corresponding to each spot; and reflecting light detected in each detection step. 1 in row m from the light
a generation step of generating a dimensional data string and combining n pieces of this data to generate n×m two-dimensional data;
and decoding continuous data from the n×m two-dimensional data.

[0011] In the present invention, data to be recorded is segmented and the segmented data is encoded to correspond to a two-dimensional array instead of corresponding to a one-dimensional array as in conventional encoding. I do.

During recording, a two-dimensional array is divided into a plurality of one-dimensional arrays. Using a plurality of light sources corresponding to a plurality of one-dimensional arrays, the light beams from the light sources are converged on the disk surface to form a plurality of spots. Each light source is modulated in accordance with the data of each one-dimensional array to record a group of optically distinguishable pits that extend two-dimensionally in the radial and circumferential directions on the disk surface.

[0013] During reproduction, the light beams from a plurality of light sources are converged to form a plurality of spots on the disc surface, and the spots are formed into the two-dimensionally spread optically distinguishable pit group. Positioning is performed, and reflected or transmitted light modulated by the pit group is detected corresponding to each spot. A one-dimensional data array corresponding to the locus of each spot is generated using each detected time-series signal, and a set of data corresponding to the set of the plurality of one-dimensional data arrays is decoded. Read out the information recorded in.

[0014]

According to the present invention, by recording data with a plurality of spots at once, it is possible to reduce the amount of spot position variation in the radial direction between each one-dimensional array. Also,
Data can be reliably detected even if the interval in the track radial direction between data in each one-dimensional array is narrowed, compared to a two-dimensional array that takes into account signal processing at the time of detection (during playback).

[0015]

Embodiment First, an overview of the system of the present invention will be explained with reference to FIG. In this example, as shown in FIG.
The data to be stored is converted into two dimensions of 4 x 2, and 4 rows 2
It shall be stored in the state of column pits.

In this embodiment, during recording, continuous storage information 901 is divided into 8 (4×2) units, and this is divided into 4 units.
It is encoded into a two-dimensional array with two rows and two columns (902), and this is
The two rows and columns are converted into a one-dimensional information array with one column and read out (903), the laser 905 is modulated based on this one-dimensional information array (904), and the laser beam is directed to a predetermined position by an optical system 906. Two rows of pits 908 converge on the disk surface.
,909 are formed. During playback, the laser 905
The optical system 906 focuses the laser light from the pit onto the pit, the light receiver 910 receives the reflected light from the pit, photoelectrically exchanges it (911), and detects a one-dimensional array signal from the photoelectrically converted signal ( 912), a two-dimensional code is obtained from this and decoded to reproduce continuous information (914).

A more specific configuration of the present invention will be explained below.

One embodiment of a basic encoding pattern of optically distinguishable pits formed on a disk surface according to the present invention is shown in FIG. For convenience of explanation, first, a two-matrix encoding pattern will be taken as an example. As shown in the figure, one block is a grid consisting of four vertical and horizontal lines, and there are round hole pits 30 at positions centered on four grid points (points where the grid intersects) within the block. Represent the data by. In this way, since there are 4 grid points in one block (2 rows and 2 columns), there are 2 possible data arrangements.
It is possible to express data in four ways, that is, 4 bits of data. An example of correspondence with recorded data is shown below the figure. Example 2
Dimensional encoding refers to associating recorded data with patterns arranged two-dimensionally as shown.

FIG. 3 shows an explanatory diagram of the pits recorded on the disc. As a data arrangement in the disk circumferential direction (arrow), the blocks 1 to 18 described above are arranged in the circumferential direction like a dashed line. Equally spaced gaps are provided between each block in the track direction so that it can be determined that the blocks are between blocks. Data is recorded between the guide grooves 20, 21, 22, and 23 of a normal continuous servo system, and the track deviation signal for positioning the recording spot uses the diffracted light from the guide groove using the normal track deviation detection method. Detect.

In the illustrated embodiment, the pits are arranged to overlap, but it is also possible to record them so that they do not overlap. In this case, the areal density becomes coarser, but a complicated signal processing system is not used during playback, and compared to the conventional method, multiple rows of pits can be recorded at once, making it possible to close the track pits to compensate for track deviation fluctuations. can.

Furthermore, when the grid spacing in the track radial direction is made smaller than the round hole pit diameter, the pits overlap in the two-dimensional array pattern as shown in the figure. In this case, it is necessary to create code rules in consideration of processing during playback. This will be described later with reference to FIG. 25.

In order to record a pattern such as that of the present invention, it is necessary to accurately control the positional relationship between recording pits.

Let us consider a method of recording pit groups that accurately controls the positional relationship. If a method is used in this embodiment in which one row of pits is recorded every rotation and then one adjacent row of pits is recorded as in a conventional optical disc, the state of the optical spot control of the apparatus changes. , the positional relationship of the pits in the track radial direction is shifted.

Therefore, in this embodiment, a plurality of spots are used to record the two-dimensional array of pits at least during the same rotation period.

FIG. 29 shows the specific positional relationship of the spots. In FIG. 29, the circular area covered with diagonal lines is the light spot 10.
0, 101, and the axis 102 connecting these spots
are slightly inclined with respect to the circumferential direction of the track, and due to this inclination, they are shifted from each other in the radial direction of the track. Normally, it would be desirable to place the two spots close together, but
Considering the characteristics of current semiconductor lasers, the spot spacing on the disk surface must be 10 microns or more. That is, considering the wide angle and light utilization efficiency of the semiconductor laser, the numerical aperture of the lens that combines the light from the semiconductor laser is about 0.15 to 0.3, and the numerical aperture of the objective lens is determined based on the characteristics of the disk substrate. It cannot be made very large, and is about 0.5 to 0.6, so the lateral magnification of the overall optical system is about 2 to 4. In the current semiconductor laser, the emission interval of the laser is set to 5 to eliminate mutual thermal interference.
It is 0 μm or more. Furthermore, since the grid spacing must be at least 1.5 microns or less from the conventional track pitch of 1.6, the spots are spaced apart in the circumferential direction of the track at the current state of the art. This amount of deviation is defined as the interval in the track radial direction of the grating described above.

In FIG. 29, for convenience of explanation, the two-dimensional array after recording is shown in the right track (the track between the grooves 21 and 22), and the relationship between the light spot and the pit in the process of recording this is shown in the left track ( track between grooves 20 and 21). Here, it is assumed that the disk plate is rotating in the direction of the arrow. The recorded pits 30', 31', 33', 34', 35', and 36' which have already been passed by the recording spot 101 are shown by solid lines. The pits to be recorded are indicated by dotted lines.

With this arrangement of spots, the same block is not recorded at the same time, but recording is completed after a time difference corresponding to the spot interval in the circumferential direction of the track, that is, within the same rotation period.

In order to form a two-dimensional array, the irradiation intensity of each recording spot is modulated in accordance with the data of each one-dimensional array, and recording is performed one-dimensionally in the circumferential direction of the track.

A predetermined encoding table is used to convert this two-dimensional array into a one-dimensional array corresponding to each recording spot. The encoding table corresponding to the two-dimensional array of FIG. 2 is as shown in FIG. This encoding table is stored in ROM (
According to the data to be recorded, data that realizes a two-dimensional array corresponding to the data is searched. In order to obtain a one-dimensional array that modulates multiple (two in the example of Fig. 4) light sources from this data, since the data is 4 bits as shown in Fig. 4, the upper 2 bits are used as the leading spot. The lower two bits correspond to the one-dimensional array that modulates the light source forming the trailing spot, and the lower two bits correspond to the one-dimensional array that modulates the light source forming the trailing spot. Furthermore, the order in the one-dimensional array is shifted starting from the most significant bits of the data.

The operation of the recording signal processing system using such an encoding table will be explained with reference to FIG. Data to be recorded 1
10 is input to the latch circuit 111, and data is stored every 4 bits according to the latch control signal 112. These 4 bits are input to the ROM 113 to search for 4 bit data that realizes a two-dimensional array. Searched data 114
is stored in the latch circuit 116 according to the latch control signal 115. The lower bits of this data 114 are read out in accordance with the first clock signal 117 and stored in a finite length shift register 118 in synchronization with the clock signal 117. Furthermore, the upper bits of this data 114 are converted into a second clock signal 1.
19 and stored in the shift register 120, which is longer than the length of the shift register, in synchronization with the clock signal 119. respective shift registers 118,1
The outputs of 20 are connected to modulators 121 and 122, respectively, and convert binary signals from shift registers 118 and 120 into analog signals 123 and 124 that modulate the emission intensity of the laser.
Convert to Here, in order to control the shape of pits after recording, the light emission waveform of the optical pulse is controlled. For example, it is known that in order to stably record a round hole pit like the one shown in Figure 1, it is better to record with a pulse shorter than the data clock using a high emission power. control. Furthermore, depending on the linear velocity and the recording medium, this modulator performs complex waveform control such as increasing the recording power for a certain period of time at the start of recording.

Laser drive circuits 125 and 126 are operated according to signals 123 and 124 from the modulators to modulate the power of light emitted from light sources 127 and 128 that form the respective spots.

In this block diagram, the length of the shift register is changed, but this is because the position shift in the circumferential direction of the two recording spots shown in FIG. 29 can be corrected by shifting the recording timing of the trailing spot. This is a periodic correction. Also, the first and second clock signals 117, 119
have the same period but are out of phase. In addition to the positional deviation correction by the shift register described above, this amount of deviation corresponds to the amount of correction for controlling the position of the even smaller light spot within the clock cycle. Furthermore, the first and second clock signals 117 and 119 have periods without clocks at regular intervals in order to provide the gap described above between blocks.

A method for reproducing data will be explained below with reference to FIG. The optical spots 100 and 101 used for recording are used to reproduce the recorded pit group. Similar to recording, tracking adjustment is performed using the diffracted light from the guide grooves 21 and 22, and each light spot is read out in a one-dimensional pit row (center line, respectively) in the circumferential direction corresponding to the one-dimensional array data to be read out. 130, 131). In order to detect data, it is necessary to determine whether there are pits at the grid points. For this purpose, a strobe pulse corresponding to the position of the grid point is created, the level of the signal read from each spot is sampled and held by this pulse, and the read signal level at the grid point is detected. By comparing this detection signal level with a specific level, it is determined whether or not there are pits at the grid points.

Here, using a normal optical system in which the numerical aperture of the objective lens is 0.53 and the wavelength of the laser is 830 nm, a pit row consisting of two pits each having a diameter of 0.8 μm is formed by changing the interval between the two pits. Figures 19, 20, and 21 show how the reproduced signals obtained during reproduction were obtained through simulation. FIG. 19 shows a case where the closest distance between adjacent pits is 0.4 μm apart, FIG. 20 shows a case where the closest distance between adjacent pits is 0.0 μm (that is, a state in which they are in close contact), and FIG. 21 shows a case where the pits overlap. By comparison, it is difficult to distinguish between FIG. 20 and FIG. 21 from the viewpoint of level margin without comparing the level of the reproduced signal at the center of the pit, but it is easy to distinguish between FIG. 19 and FIG. 20. Therefore, the following encoding rules are used to determine the pit positional relationship so that FIGS. 20 and 21 do not occur at the same time.

[0035] Here, the encoding rules (code arrangement relationships) of this embodiment will be described with reference to FIGS. 25 to 27.

That is, in this embodiment, overlapping of pits is allowed, and a block that is a plurality of overlapping pits and an adjacent block are arranged as close as possible to each other in order to increase the density of the optical disc. It is desirable to do so. However, since mutual interference occurs between pits during readout, each block is arranged so that the outermost pit interval provided within each block is separated from the interference distance determined by the optical system.

When storing a round hole pit, the pit size is W, and the spot size for reading is Ws. First, interference between individual pits will be explained with reference to FIG. 25.

For example, when a spot is located at position 701-1 between pits 700 and 701, the edge of this spot is affected by the outer circumference of pit 700, and therefore the signal level at the center 701-1 of pit 701 is affected. may be received. The condition under which this effect can be ignored is 700.
This is when the distance L between -1 and 701-1 satisfies the following conditions.

[0039]L≧W/2+Ws/2
(Formula 1) In principle, Ws is Ws=k×λ/NA, where the laser wavelength is λ and the numerical aperture of the objective lens is NA.
(Formula 2) k is 0.85, but in an actual optical system, it becomes approximately 1.0 due to assembly, manufacturing, etc. The above is shown in Figures 19 to 21.
The results agree well with the simulation results. It is clear from the simulation results that when pits overlap, the simple superposition of solitary waves, which is often used in conventional magnetic disks, does not hold. This is due to the lack of optical resolution and the fact that the optical properties of the overlapped area are the same as those of the non-overlapping area. Therefore, even if the signals are overlapped as shown in the simulation, the signal level at the overlapped portion changes only slightly. The specific values are: wavelength 830nm, NA 0.5
3. If the pit diameter is 0.8 microns, L will be approximately 1.2 microns. In the example, the grid spacing was selected to be 1/3 of this length, ie, 0.4 microns.

Mutual interference between pits is two-dimensionally isotropic not only in the track direction but also in the track radial direction. For this purpose, the grid spacing in the track direction is a, and the grid spacing in the track radial direction is b, and a and b are now taken to be equal. Then, a circle with a diameter equal to the spot diameter is drawn from the center of one pit, and the pits are arranged so that the edges of other pits do not touch this circle and the pit centers are at the grid points.

Next, the case where the pits are not individual but overlap will be explained with reference to FIGS. 26 and 27. In this implementation, it is recognized that pits 708 and 709 overlap, and in this case, pits 709 and 710, which correspond to the outermost pits, are at the same distance as pits 700 and 701 in the track direction in the above example. You need to make a connection. A block of connected pits is formed by overlapping pits, but the relationship between each block is that the pits of other blocks are placed in a circle with the outermost pit center as the center and the diameter of the spot as the diameter. This is a relationship where the two are not in contact. In this embodiment, as shown in FIG. 27, the lattice spacing a,
b is both 0.4 micron, pit diameter is 0.8 micron,
If the spot diameter is 1.6 microns, the pit 711'
, 712', and 713', lattice points where pits of other blocks can exist are shown as white circles, and lattice points where pits cannot exist are shown as black circles. 2 in the information rack below
Although the dimensional pit array has been described, the relationship between tracks is as follows.

As shown in FIG. 1, if the distance in the disk radial direction of the laser spot created from a plurality of light sources is L, the track pitch of the two-dimensional code is p, and the spot size is Ws, then the following relationship is established. is necessary.

p≧LWs Next, a method for creating the strobe pulse described above will be described.

In order to create a strobe pulse, it is necessary to detect a reference signal for creating a timing for creating a pulse from recorded data. There is also a self-clocking method that uses the data signal as it is as this signal, but No. 2 in FIG. As shown in 15, if a pattern without pits exists in the recorded pattern after encoding, it may become impossible to detect a signal for timing generation from the recorded data. Therefore,
As shown in FIG. 6, synchronization marks 132 are included in the recorded data.
132', 133, and 133' are provided, and the format of the recorded data is determined so that they always appear at specific intervals.

Although it is preferable to provide this synchronization mark on the disc in advance, it is also possible to form it using the recording/reproducing apparatus of this embodiment during recording. In this way,
Although the data efficiency is slightly reduced, the reference signal for creating strobe pulses can be stably detected.

Synchronization marks 133, 133', 1 in FIG.
32, 132' do not appear in the recorded data. The pattern is three pits overlapping each other, followed by one pit 134, 134', 135, 135' apart. First, a pattern of three overlapping pits is detected, and isolated pits 134, 134', 1 which are separated by a predetermined distance from this pattern are detected.
Predict the position of 35,135'. isolated pit 134,
By taking the differentiation of the reproduced signals from 134', 135, and 135' and finding the zero cross point, the isolated pit 13
The center positions of 4, 134', 135, 135' are detected. Since the center position of the isolated pit and the grid point coincide, a reference position for detecting the timing of the grid point can be obtained. Detect such reference points at regular intervals and calculate the PL
A reference clock is generated by a well-known clock generation means such as L (phased locked loop).

The reproduced signal processing system will be explained using FIGS. 7 and 8. Here, the light source used in the recording apparatus shown in FIG. 5 can be used in common. Light from this light source is irradiated onto the pits as spots, and reflected light from each spot is detected by photodetectors 140 and 141 corresponding to each spot. The signal after photoelectric conversion is amplified by amplifiers 142, 143, and peak detection circuits 144, 145 and synchronization part detection circuits 146, 147,
It is input to sample and hold circuits 148 and 149. As described above, the peak detection circuits 144, 145 differentiate the signals from the isolated pits 134, 134', 155, 155' to detect the zero point, and detect the pulses 150,
151 is generated.

The synchronization detection circuits 146, 147 detect pit patterns 132, 132', 133, 133' in which three round hole pits overlap as shown in FIG. 6 from the reproduced signal. To do this, the reproduced signal is sliced at a specific level, and it is detected that the pulse length after slicing is within a certain range of specific lengths. In normal data, the three round pits do not overlap due to the encoding rules, so
It is possible to detect the synchronization mark part.

Gate pulse 1 with a constant width that covers the position of the isolated pit after a predetermined time from the synchronization part
Create 52,153. This gate pulse 152,1
53 and the output pulse 15 of the peak detection circuits 144 and 145
0,151 is input to the gate circuits 154, 155, and pulse 15 corresponding to the center of the isolated pit immediately after the synchronization part is input.
Create 6,157.

These signals 156 and 157 are connected to the PLL 158,
159 to create clock signals 160 and 161 that are synchronized with these signals 156 and 157 and have a frequency that is an integral multiple of the repetition frequency of these signals 156 and 157. These clock frequencies 160 and 161 are the aforementioned recording clock 11.
7,119, the frequencies are almost the same.

Synchronous detection pulses 162, 163 and clock signals 160, 1 are supplied to sample and hold circuits 148, 149.
61 is input, the level of the reproduction signal from the data pit is sampled and held. The outputs 164 and 165 are input to level comparators 166 and 167, and converted into binary signals depending on whether the level of the input signal is higher than a specific level. These binary signals 168, 169 are input to first-in/first-out memories 170, 171, and the timing 172 of the control clock signal, which will be described later, is
173, the data is stored in the memories 170 and 171. The above configuration is a configuration of a series of processing circuits corresponding to each spot, and the apparatus in this embodiment has two systems of the same processing system described above. Hereinafter, numbers 1 and 2 will be given to distinguish the elements of each component block. One-dimensional array data 17 stored in two memories 170 and 171
4,175 must be read out and rearranged into a two-dimensional array of data. For this purpose, it is necessary to align the one-dimensional array of binary data recorded at the same radial position on the disk surface. Therefore, from among the data of each one-dimensional array, the synchronization mark parts 132, 132', 133, 133
’ as a reference, each data is clocked 160,
Number them in units of 161. Thereafter, data with the same number stored in each memory is read out at the same timing 176 and 177 for each one-dimensional array. For this purpose, first and second timing control circuits 178 and 179 are provided to control the timing of storing data in each memory 170 and 171. In the write first and second timing control circuits 179 and 178 of this memory, the first and second PLLs, 158,
Using the clocks 160, 161 and synchronization detection pulses 162, 163 created in step 159, the synchronization mark section 132,
132', 133, 133' are detected, and then the pulses 172,
Create 173. Then, data in a one-dimensional array is stored in each memory 170, 171 in order based on the synchronization mark sections 132, 132', 133, 133'.

The timing for reading this is the read pulses 176 and 17 from the read timing generation circuit 180.
7 controls each memory 170, 171. These timings 176 and 177 correspond to each of the first and second synchronization detection sections 14
The time of synchronization pulses 162 and 163 from 6 and 147 is observed, and pulses 176 and 177 to start reading are generated after the later synchronization pulse arrives. This pulse period may be created from the reference clock 181 with a constant period, or a clock created by a PLL used in the signal processing system in which the synchronization pulse arrives later or a created clock may be used. . In this way, the first and second serial data 174, 175 read from the memory
The recording radius positions are completely aligned.

This serial data 174, 175 is shown in FIG.
Each block is fetched into the latch circuit 182 as shown in FIG. The data latch signal 183 is generated by dividing the clock 181 by two in the read timing control circuit 180 described above. 4-bit data 1 indicating a two-dimensional array for each block
84 is input to a ROM (read only memory) 183 having a conversion table opposite to that shown in FIG.

This data 186 becomes data 187 demodulated by the signal processing circuit.

Up to now, the pit group of the recording block has been (2
An example using four lattice points (rows, 2 columns) has been described, but examples using 6 (3 rows, 2 columns) and 8 (4 rows, 2 columns) lattice points are shown below. Figure 9 shows 2 when there are 6 grid points (3 rows, 2 columns).
This is an example of a dimensional array, and the recording data can theoretically represent bit data. However, if the number of pits in this block is too large, the amount of reflected light during reproduction will decrease, so in this example, these blocks are avoided and 5-bit data is made to appear. When recording, it is converted into two (two columns) one-dimensional arrays. The conversion table maps 5 bits to 6 bits. Each one-dimensional array uses the upper 3 bits and lower 3 bits of these 6 bits. Each one-dimensional array is recorded in order from the most significant bits.

FIG. 1 shows an example in which pits are recorded on a disk using this method.

FIGS. 10 to 13 are examples of two-dimensional arrays in which each child point has eight child points, and it is preferable to represent 7-bit data as recording data for the same reason as described above. When recording, it is converted into two (two columns) one-dimensional arrays.

The conversion table makes 7 bits correspond to 8 bits. Each one-dimensional array consists of the upper 4 bits and lower 4 bits of these 8 bits.
Use bits. In any case where each one-dimensional array is recorded in order from the most significant bits, in order to demodulate the data, an inverse conversion table corresponding to the modulation is used as described when the recorded data is 4 bits.

FIG. 28 shows an embodiment in which the number of lattice points is further increased in the row and column directions. Track direction (column direction)
There are 56 grid points, 7 in the track radial direction (row direction) and 8 in the track radial direction (row direction). Since there is a relationship of C=K-1 between the conventional number of grid points K and the number of data bits C that can be represented thereby, data of about 55 bits can be represented in this embodiment as well. From the viewpoint of areal recording density, the encoding of the present invention can improve it compared to conventional methods, but the relationship between the density improvement ratio and the number of lattice points is based on trial calculations. One-digit improvement can be expected, and at the same time, one-digit improvement in transfer rate can be expected. In order to record the pit array of this embodiment, each of LD1 and LD2 in FIG. 22, which will be described later, is constituted by an array laser equipped with four commercially available lasers. As a result, spots 103, 104, 105, and 106 are formed on the disk surface by one array laser, and spots 101, 102,
107 and 108 are formed by another array laser. The pits recorded by these spots are formed according to the coding rules described in connection with FIGS. 25-27.

Furthermore, as the distance between pits and the distance between tracks in a one-dimensional array are reduced in order to increase the density, mutual interference between signals becomes stronger and the level margin for signal detection decreases. Therefore, we will discuss a method to remove interference between signals and improve the detection margin.

[0061] When playing back from the spots as shown in Fig. 1, the signal detected from the right column is I1(t), the signal detected from the left column is I2(t), and the right and left spots are If the time delay of (t-τ)+ηi2(t)I2(
t)=i2(t)+ξi1(t-τ). From this, the signal without interference can be found using the following equation.

[0062] Therefore, by performing this calculation from the detection signal, data can be detected without interference. In the example of FIG. 6, the coefficient η of this interference is about 0.3 to 0.4.

The specific circuit configuration for performing this calculation is shown in FIG.
4. The same drawing numbers are used for parts that are substantially the same as those in the embodiment of FIG. 7. In this embodiment, the signal is
Perform D conversion and digital processing. Sample and hold circuit 148 receives signals 200 and 201 from detectors 140 and 141.
, 149, the level of the signal corresponding to the grid point is captured using the clocks 160, 161 created in the same manner as described in the embodiment of FIG.
3 and converted into digital signals 204 and 205. This signal is taken into the memory FI/FO (first in first out) 206, 207, and as explained in FIG. 7, the time difference between the two spots is corrected, and the signal level at the same position on the disk radius is adjusted. The digital values are stored in the first and second parallel data 208 and 2 for each spot.
Detected as 09. As shown in FIG. 12, these data signals 208 and 209 are input to arithmetic units 210 and 211, and calculations corresponding to the above-mentioned formulas are performed.
Outputs 12,213. Comparator 214,
215 and compare the levels and serial data 1 and 2.
174' and 175' are detected. The subsequent processing is shown in Figure 8.
Processing similar to that is performed to demodulate data 187 corresponding to the two-dimensional array data.

When the number of columns in the vertical direction increases to q as shown in FIG. 28, the detection signal Inp(t) of the p-th column becomes Ip(t)
=ip(t)+ξip-1(t-τ)+ηip+1(t
+τ) By solving this n-dimensional simultaneous equation, it is possible to obtain each signal ip from the p-th column without interference. At this time, i-1 and iq+1 are set to zero. Here 0≦p≦q.

Another embodiment will be described with reference to FIG. 16.

In the embodiment shown in FIG. 15, it is necessary to provide the interference coefficients ξ and η to the arithmetic units 210 and 211. This coefficient ξ,
η changes depending on track deviation, spot shape, and track pitch. In this example, these effects are reduced,
The purpose is to enable even higher density. That is,
In this embodiment, the relative levels are compared by taking the difference between the signals I1 and I2 from the two spots on the right and left, and even if there is interference between adjacent pits, data can be detected with high reliability. I do. This method is expressed using the above formula: I1(t-τ)-I2(t)=i1(t-τ)-i2(
t)+ηi2(t)-ξi1(t-τ) If η and ξ are almost equal, I1(t-τ)-I2(t)≒ (1-η)×[i1(t-τ)-i2( t)], resulting in only amplitude fluctuations. In this way, it is possible to stably detect a difference between signals without interference by compensating for fluctuations using an AGC (auto gain control) circuit or the like. The difference signal takes three values: + level, 0 level, and - level depending on the pit arrangement. Let CH1 be the signal processing sequence that generates the first parallel data 208, and CH2 be the signal processing sequence that generates the second parallel data 209.If the difference between the first parallel data 208 and the second parallel data 209 is taken, the ternary level and each The relationship with data on CH is as follows.

[0067]

[Table 1]

The presence or absence of adjacent pits can be determined from this table. That is, when the level is positive, there is a pit hole on the right side in FIG. 1, but there is no pit hole on the left side. Conversely, if the level is negative, there is no pit hole on the right side, but there is a pit hole on the left side.

Here, if the data of CH1 and CH2 are the same, the level becomes zero, and it is not possible to determine whether the left and right pits exist together or not. Therefore, in this case, the levels of CH1 and CH2 are set using another binary comparator 2.
20, 221 is used for detection. That is, the outputs of the ternary comparator 222 and the binary comparators 220 and 221 are input to the logic processing unit 223, and when the data of CH1 and CH2 are the same, the values of the data of CH1 and CH2 are used for discrimination.

In the case of a write-once medium, the reflected light decreases when there are pits as obtained from the waveform simulation, so in order to detect the presence or absence of pits, the signal from the place where the pits are present is sample 1 and set to a certain value. For example, when the detection level is low, it is assumed that there is a pit and is associated with data of "1", and when the level is compared and the level is high, there is no pit and it is associated with data of "0".

When the data of CH1 and CH2 is 1, adjacent left and right pits exist, and when it is 0, neither pit exists. The determination results are output as first and second serial data 174'' and 175'', which are data at the same radial position of CH1 and CH2, respectively. The subsequent processing is similar to that shown in FIG. 15, and the corresponding data is demodulated from the two-dimensional array data.

Further, a pit arrangement suitable for this detection method will be described with reference to FIG. The right end is the recording pattern of the pit array explained in the above embodiment. Here, the recording positions of the data in the two one-dimensional arrays at the right end (the centers of the pit rows are set to 300 and 301, respectively) were made to coincide with the disk radius, but the pit array of this example shown on the left ( When the centers of the pit rows are set to 302 and 303, respectively, the pits are shifted from each other so that the position where data of one array (the center of the pit row is 303) is recorded at the position of the gap between the blocks so far. In this way, no matter what kind of recorded data is recorded, the data of each one-dimensional array will not overlap at the disk radial position, and the zero level difference between CH1 and CH2 as explained in the table above will not occur.

Therefore, each one-dimensional array signal can be detected independently by simply taking the difference between CH1 and CH2, and no processing is required when the level difference is zero. It goes without saying that when detecting the signals of each one-dimensional array, the clock timings during recording and reproduction are shifted. However, there is no need to essentially change the circuit configuration described above. This configuration is shown in FIG.

Furthermore, this method applies not only to two-dimensional arrays, but also to
Only the conventional one-dimensional array can be applied to data recording. That is, the conventional one-dimensional array data can be divided into two bits and recorded alternately as CH1 and CH2. It is also possible to alternately record two completely independent one-dimensional arrays. The pit arrangement on the disk surface and the recording/reproduction signal processing system in two-dimensional recording have been described above.

Next, the optical system and spot control method for realizing these will be explained in detail. FIG. 22 is an example of realizing two spots. This can be used as a laser light source.
This is an example using a laser array 400 in which several laser chips are housed in one package. As shown in FIG. 5A, a semiconductor laser array is used as a light source, in which two laser chips LD1 and LD2 having different wavelengths are mounted in one package with their active layers facing each other. LD1 has a wavelength of 780
It is a nm laser. On the other hand, LD2 is a laser with a wavelength of 830 nm. Optical spots SP1 (wavelength 780 nm) and S formed by both laser light sources on the disk
The positional relationship of P2 (wavelength 830 nm) is shown in Figures 1 and 22.
On the same track as in (b), the spot SP
2 in advance.

FIG. 23 shows an embodiment of the specific structure of the optical head according to the present invention. This is an example in which a two-wavelength hybrid laser array 400 in which two laser chips with different wavelengths are arranged facing each other and housed in one package is used as a semiconductor laser light source. Laser beam 80 emitted from the two-wavelength hybrid laser array 400
1 (wavelength; λ1 = 830 nm) and laser beam 802 (
Wavelength; λ2 = 780 nm) is the collimating lens 402
It becomes a nearly parallel beam.

The two laser beams enter the beam splitter 403 as p-polarized light. After that, the optical path is turned back by the rising mirror 804, and the aperture lens 401
The image is narrowed down onto the disk 404. The two laser beams reflected by the disk are reflected by the beam splitter 403, pass through the convex lens 812, and then pass through the wavelength separation filter 40.
Reach 5. The wavelength separation filter transmits a laser beam 801 with a wavelength of 830 nm and reflects a laser beam 802 with a wavelength of 780 nm. The laser beam 802 reflected by the wavelength separation filter 405 is guided to a detection optical system using a detection prism 808, and is passed through a first photodetector 810-1 and a second photodetector 810, which constitute a front-rear differential defocus detector. -2
The light is received by A data signal, an address signal, a focus error signal, and a tracking error signal are obtained from the first photodetector 810-1. On the other hand, the wavelength separation filter 405
The laser beam 801 transmitted through the third photodetector 807
The light is received by A data signal is output from the third photodetector 807;
Obtain address signal and tracking signal.

The diaphragm lens 401 is attached to a diaphragm lens actuator (not shown). This diaphragm lens actuator moves the diaphragm lens in the direction of vertical vibration of the disk and in the direction of track deviation. It may be a so-called two-dimensional actuator, or it may be an actuator that simply moves the aperture lens only in the direction of vertical vibration of the disk. Further, although the raising mirror 804 is depicted as a prism in the figure, it goes without saying that it may be a so-called galvano mirror.

Next, the detection prism optical system will be explained with reference to FIG. The light receiving surface of each detector is divided into four parts as shown in the figure. Two receivers 40 on the left and right of the first and second detectors
The sums of 5, 406, 405', and 406' are calculated by differential amplifiers 409 and 410, respectively, and the difference between the detectors is calculated by differential amplifier 41.
1, the defocus signal AF is detected. The tracking deviation signal TR1 is the first and second
Light receivers 407, 408, 407', 40 above and below the detector
8' is taken by differential amplifiers 409 and 410, and the difference between the detectors is taken by differential amplifier 414. λ2
Data signals and pre-pit signals from pits on the readout side with a laser beam having a wavelength of are detected from the sum of the light receiving surfaces of the first and second photodetectors. Furthermore, a third detector 807
As shown in FIG. 24, it has the same shape as the above-mentioned detector, and the tracking signal TR2 is sent to the upper and lower light receivers 407.
The data signal from the pit on the side to be read out by the laser beam of wavelength λ1 is detected from the sum of the light receivers of this third detector. Note that this example uses the case where a write-once type recording film is used, so the intensity of the reflected light used to read the pit information is used. However, when using a magneto-optical recording film, the polarization of the reflected light is used to read the domain information. It can be read by

Each control signal processing method during recording and reproduction will be explained below.

Track deviation detection and defocus detection are necessary for controlling the light spot. Here, the case where a write-once type is used as the recording film will be mainly explained. This is because when a magneto-optical recording film is used, the data does not affect the detection of the tracking control signal, so signal processing as described below is not particularly necessary. In addition, focus shift detection has fewer problems such as gain fluctuations and offsets than track shift detection, so it can be detected by detecting only the low frequency components of reflected light during recording and reproduction. Specifically, an amplifier 412 with low frequency characteristics is used, and a signal W/R-MODE4 indicating the recording/reproduction mode is generated in advance so that the level of reflected light during recording is higher than that during reproduction.
13 to switch the gain of the amplifier 412. The following tracking control signal refers to a track deviation signal. When recording is performed using the diagonally shaded spots as shown in FIG. 1, the tracking control signal of the light spot from the trailing spot is affected by the pit recorded by the preceding spot. In the write-once type recording film, in the case of a perforated type, the amount of reflected light decreases where there are data pits, and the detection sensitivity of the tracking control signal decreases, or in some cases, an offset may occur. In this embodiment, in order to avoid being affected by recording pits, the fact that there are no recording pits between blocks is used to detect the tracking control signal only in this portion. As a method for this purpose, since the level of reflected light is high where there are no recording pits, the areas where the level of reflected light is high are selectively detected out of the output waveform from the light receiver that detects the control signal. During recording, the recording power increases only in the block portion, and since the recording timing is known, the value immediately before the detection signal is sampled and held only when the recording pulse is emitted. At the time of reproduction, a part with a high level of reflected light is selectively detected among the output waveforms from the light receiver that detects the control signal for both the leading spot and the trailing spot.

FIG. 2 shows the circuit configuration for performing the signal processing described above.
This will be explained with reference to 4. Each receiver 407, 408,
Sample and hold circuits 424, 426, 428, 430 output from 407', 408', 407", 408"
, 418, 419, and the first and second gate signals WR-GATE 420, created from the respective recording pulses.
432 is used to control the recording period to be held. The peak hold circuits 421, 422, 42
5, 427, 429, and 431, and continuously detect areas where the signal level is high. After these signal processes, differential amplifiers 412, 413, 414, and 423 calculate the difference between each light receiver. Although analog processing has been described in this embodiment, the output of the light receiver may be A/D (analog-to-digital) converted, and then processing such as sampling, holding, and peak detection may be performed.

The track deviation signal TR must be such that the leading spot and trailing spot are positioned at equal distances apart from the center of the track on both sides. To detect such a signal,
The sum of the track deviation signal TR1 from the preceding spot and the track deviation signal TR2 from the following spot is calculated. Assuming that the spot positional deviations are α and β, the track pitch is p, the detected amplitude is A, and the spot positional deviation variable is X, the track deviation signals from each spot can be expressed as follows.

[0084]

[Math 1]

[0085]

[Math 2]

[0086] Taking the sum of these, we get

[0087]

[Math 3]

##EQU1## The position of the zero point of the detected signal TR is the midpoint of each spot. Using this signal, the leading and trailing spots are positioned at equal distances on both sides from the center of the track.

In the embodiments described above, an example of an optical disk has been described, but the present invention can be used in optical information recording/reproducing media such as optical drums and optical cards. Furthermore, it goes without saying that the present invention can be used not only for recording and reproducing devices but also for devices exclusively for recording or reproducing. Furthermore, it is applicable not only to the write-once type recording film mentioned in the embodiment but also to a magneto-optical recording film.

This method is suitable for CLV (Constant Linear Density) or MCAV (Modified Constant Linear Density), which are used as a data recording method for optical discs. In other words, in both methods, the bit density at the radial recording position of the disk is approximately equal, so unlike this method, the spot interval in the track advancing direction is constant, and the interval changes depending on the radial position of the disk. If not, the number of bits falling within the interval will hardly change depending on the recording radial position. As a result, the shift register 12 shown in FIG.
The capacity of the first-in/first-out memory for correcting the number of zero registers and the timing shift during reproduction shown in FIG. 7 can be set to a constant value regardless of the recording radius. In the case of CLV (Constant Linear Density), the clock pulse in FIG. 5 and the reference clock generated from the reference clock generation circuit 181 in FIG. 7 may be constant regardless of the recording radius; - linear density), the above clock needs to be changed according to the disk radial position. To do this, in order to detect the radial position of the disc, a mark that can optically identify the radial position is recorded on the disc in advance, and this is used to recognize the radial position, and the clock frequency is determined in advance. Set. Alternatively, there is a method in which the position of the recording/reproducing head is read using a scale located at a position different from that of the disk, and a predetermined clock frequency is thereby set.

[0091]

According to the present invention, it is possible to increase the density of information stored on an optical disk.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a two-dimensional array of pit groups on an optical disc according to an embodiment of the present invention.

[Fig. 2] An explanatory diagram of a pit group in a two-dimensional array of the present invention

[Figure 3]
Arrangement diagram of recorded pit groups

[Figure 4] Encoding table for creating a two-dimensional array

[Figure 5] Block diagram of signal recording system

[Figure 6] Pattern diagram of synchronization mark section for creating a clock

[Figure 7] Block diagram of data playback system

[Figure 8] Block diagram of data playback system

[Fig. 9] Explanatory diagram of a two-dimensional array corresponding to 5 bits of recording data

[Fig. 10] Explanatory diagram of a two-dimensional array corresponding to 7 bits of recording data

[Fig. 11] Explanatory diagram of a two-dimensional array corresponding to 7 bits of recording data

[Fig. 12] Explanatory diagram of a two-dimensional array corresponding to 7 bits of recording data

[Fig. 13] Explanatory diagram of a two-dimensional array corresponding to 7 bits of recording data

[Figure 14] Block diagram of the playback processing system when there is strong interference between one-dimensional arrays

[Figure 15] Block diagram of the playback processing system when there is strong interference between one-dimensional arrays

[Figure 16] Block diagram of the playback processing system when there is strong interference between one-dimensional arrays

[Figure 17] Block diagram of the playback processing system when there is strong interference between one-dimensional arrays

[Figure 18] Explanatory diagram of pit arrangement that reduces interference

[Figure 19
] Relationship diagram between pit spacing and signal output

[Figure 20] Relationship diagram between pit spacing and signal output

[Figure 21] Relationship diagram between pit spacing and signal output

[Figure 22] Configuration diagram of the optical system for forming two spots

FIG. 23 is a block diagram illustrating a method for detecting control signals from the optical system that forms two spots.

FIG. 24 is a block diagram illustrating a method for detecting control signals from the optical system that forms two spots.

FIG. 25 is a diagram showing the encoding rules of the embodiment of the present invention.

FIG. 26 is a diagram showing the encoding rules of the embodiment of the present invention.

[Figure 27
] A diagram showing encoding rules according to an embodiment of the present invention.

FIG. 28 is an explanatory diagram of an embodiment in which a recording block has 7 lattice points in the track direction and 8 in the track radial direction.

[Fig. 29] Explanatory diagram of the relationship between recording/reproducing spots and pit groups

FIG. 30: System diagram showing an overview of the present invention

[Explanation of symbols]

901...Continuous storage information, 905...Laser, 906...
Optical system, 908...2 rows of pits, 909...2 rows of pits, 910...light receiver

Claims (22)

[Claims] 1. Buffer means for storing continuous storage data in units that are converted into two dimensions; conversion means that converts the data in the units into an n×m two-dimensional data array;
a recording means having m light sources, reading out the n×m two-dimensional data array by dividing it into m one-dimensional data strings, and controlling the m light sources according to these data strings; an optical means for converging light beams from m light sources to form m spots on the disk surface, and optically transmitting the recorded data on the disk surface with a two-dimensional spread of n x m. An information recording and reproducing device that records information as a group of identifiable information identifiers. 2. The information recording and reproducing apparatus according to claim 1, wherein the disc is a write-once type, and the information identifier group is a pit group. 3. The information recording and reproducing apparatus according to claim 2, wherein in the n×m pitch group, n corresponds to a row in the track direction of the disk, m corresponds to a column in the track radial direction, and n is 3 or more. , m is an integer of 2 or more. 4. Reproducing data stored by a storage method that converts continuous data into data with a two-dimensional spread of n×m and records this as a group of optically distinguishable pits on an optical disk. an information recording/reproducing apparatus comprising: m light sources; an optical means for converging light beams from the m light sources to form m spots on a disk surface;
m detection means for detecting reflected light from the pit group corresponding to each spot; m detection means for detecting reflected light from the pit group corresponding to each spot; generating means for generating m one-dimensional data strings from the reflected light and generating n×m two-dimensional data by combining n pieces of data;
An information recording/reproducing device having demodulation means for demodulating continuous data from dimensional data. 5. The information recording and reproducing apparatus according to claim 2, further comprising positioning means for positioning said m spots in said pit group on a disk surface; m detection means for detecting reflected light;
generating means for generating m one-dimensional data strings from the reflected or transmitted light detected by the respective detection means, and generating n×m two-dimensional data by combining n pieces of data; An information recording/reproducing device having demodulation means for demodulating continuous data from two-dimensional data. 6. The information recording and reproducing apparatus according to claim 2, wherein the m spots are formed at positions where an axis connecting the spots is inclined with respect to the radial direction of the track. 7. The information recording and reproducing apparatus according to claim 4, wherein the m spots are formed at positions where an axis connecting the spots is inclined with respect to the radial direction of the track. 8. The information recording and reproducing apparatus according to claim 5, wherein the same light source is used for recording and reproducing. 9. The information recording and reproducing apparatus according to claim 2, wherein said recording means has means for giving a delay of time τ between the read m columns of one-dimensionally arranged data sequences, and said m light sources are The information recording and reproducing apparatus performs control by giving a delay of τ, and the optical means forms the spots at positions delayed by a time τ with respect to the track direction. 10. The information recording and reproducing apparatus according to claim 4, wherein the optical means forms the spots at positions delayed by a time τ with respect to the track direction, and the generating means forms the spots in the detected m columns. An information recording and reproducing apparatus comprising means for compensating delay time τ between one-dimensional array data sequences, and generating n×m two-dimensional data by compensating for delay time τ with the compensating means. 11. The information recording and reproducing apparatus according to claim 4, wherein the generating means has a calculating means for performing a calculation to remove interference between the generated m-column one-dimensional data strings, An information recording and reproducing device that removes interference using means and generates n×m two-dimensional data. 12. The information recording and reproducing apparatus according to claim 4, wherein the generating means includes a difference calculation means for comparing signal levels of adjacent data of the one-dimensional data string; It has a judgment output for judging the state of adjacent pits from the mutual data signal level and the output of the difference calculating means, and the generating means uses the output of the judgment means to
An information recording and reproducing device that generates xm two-dimensional data. 13. The information recording and reproducing apparatus according to claim 5, wherein the optical means records the pits adjacent in the track radial direction within the pit group by shifting them in the track direction, and the generating means records the generated one of the pits. It has a difference calculating means for comparing the signal levels of adjacent data of the dimensional data string, and a judgment output for judging the state of adjacent pits from the output of the difference calculating means, and the generating means is configured to compare the signal levels of adjacent data of the dimensional data string, and the generating means compares the signal levels of adjacent data of the dimensional data string. An information recording and reproducing device that generates n×m two-dimensional data using 14. The information recording and reproducing apparatus according to claim 5, wherein a group of synchronizing pits appearing at specific intervals is recorded on the disk surface. 15. The information recording and reproducing apparatus according to claim 14, wherein the synchronization pit group is recorded as a pit group having a two-dimensional spread of (n+1)×m. 16. The information recording and reproducing apparatus according to claim 4, wherein the positioning means includes tracking positioning means for positioning the spot in the tracking direction using diffracted light from a guide groove of a track of the disk; identification means for identifying a part of the track where a pit is present and a part without a pit; An information recording and reproducing device that performs positioning. 17. A device for recording and reproducing information using a plurality of laser light sources at least during the same rotation, where L is a distance in the disk radial direction of a laser spot created by the plurality of light sources, and 2. If the track pitch of the dimensional code is p, then p≧L+W between the spot size Ws
A recording and reproducing device that has a relationship of s. [Claim 18] As a two-dimensional encoding method, the disk surface is divided into two-dimensional grids, and information pits are arranged at each grid point, two-dimensional overlapping of the information pits is allowed, and the information In a recording/reproducing device, the relationship between blocks, which are multiple overlapping pits, is such that the distance between the outermost pits of each block is greater than the interference distance determined by the optical system. 19. Reproducing data stored by a storage method that converts continuous data into data with a two-dimensional spread of n×m and records this as a group of optically distinguishable pits on an optical disk. An information reproducing apparatus comprising: m light sources; optical means for converging light beams from the m light sources to form m spots on the disk surface; a positioning means for positioning the pit group; m detection means for detecting reflected light from the pit group corresponding to each spot; Generate a data string, combine n pieces of data, and combine n x m 2
An information reproducing device comprising: generating means for generating dimensional data; and demodulating means for demodulating continuous data from the n×m two-dimensional data. 20. Encoding the recorded information in two dimensions; and converting the recorded information into a one-dimensional information array; modulating a plurality of laser light sources using the information array to encode the two-dimensional information on the disk surface. A step of recording the code; A step of reproducing this two-dimensional information using a plurality of laser light sources; A step of photoelectrically converting the reproduced signal; A step of detecting a one-dimensional array signal from the photoelectrically converted signal. An information recording and reproducing apparatus comprising; and a step of decoding two-dimensional information using these signals. 21. Storing continuous storage data in units that are converted into two dimensions; encoding into an n×m two-dimensional data array corresponding to the data in the units;
reading out the n×m two-dimensional data array by dividing it into m one-dimensional data strings, and controlling the m light sources according to these data strings; converging the light beams from the m light sources; , forming m spots on the disc surface; recording data to be recorded on the disc surface;
recording the m spots as an optically distinguishable pit group having a two-dimensional spread of ×m;
a step of locating the pit group on the disk surface; a detection step of detecting reflected light from the pit group corresponding to each spot; and m columns of one-dimensional data from the reflected light detected in each detection step. An information recording and reproducing method comprising: generating a sequence and combining n pieces of data to generate n×m two-dimensional data; and decoding continuous data from the n×m two-dimensional data. Method. 22. The information recording and reproducing method according to claim 21, wherein the generating step of generating the two-dimensional data further includes the step of generating a mark synchronization signal using synchronization marks provided at equal intervals on the disk surface. and; dividing the frequency of the mark synchronization signal to generate a pit readout synchronization signal; sampling a signal of reflected light from the pit group detected in the detection step with the readout synchronization signal; An information recording and reproducing method comprising a step of comparing a sampled signal with a signal of a specific level and determining the presence or absence of pits based on the result.