JP3445313B2 - Optical information reproduction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium recorded on a recording medium.
Optical information reproduction for reproducing optical information with high resolutionMethodAbout. [0002] 2. Description of the Related Art For example, in a CD or a magneto-optical disk,
To read the recorded information on the recording medium, use a very small spot.
A recording medium using the converged laser light as a light spot for reproduction
The recording pits formed on the media surface.
Due to the change in light reflection intensity due to no light and the direction of magnetization of the recording film
The change in the plane of polarization is detected by the optical element of the optical pickup.
To change the light amount according to the recording signal.
It is recorded by detecting with an optical sensor such as a photodiode.
The recording information is reproduced. Recently, a recording medium formed on a recording medium has been used.
Increase recording density by reducing recording pit diameter
It is considered to be able to record such information.
However, the recording pit diameter of the recording medium is
As the size is reduced, the optical beam for reading to read the recording pits
Although it is necessary to reduce the pot diameter, the NA of the objective lens
Size of the light spot for reproduction due to
There is a limit to how high the resolution can be played.
There was a problem that could not be. Conventionally, high-density recording is reproduced with high resolution.
For example, Japanese Patent Application Laid-Open No. Hei 4-255946 and Japanese Patent Application No. Hei.
One disclosed in Japanese Patent Publication No. 225885 is known.
In other words, this is a magneto-optical recording medium and a reproducing beam path.
Using the temperature distribution due to relative movement with the pot,
The reproducible area of the air recording medium is set to a predetermined temperature range during reproduction.
So that only the high resolution of the resulting
It is intended to increase the image resolution. [0005] However, such a device is not suitable for light spots.
Playback is possible in the area on the media surface where the
The magnetization of the reproducing layer other than the active temperature region is the same direction as the reproducing magnetic field
In the recording layer only within the reproducible temperature range.
The recorded pits are transferred to the reproducing layer, and the binary information 0 and 1 are read.
This method is used only for magneto-optical recording media.
Media that reads reflectance changes such as phase changes
Not applicable to the body. In addition, the I
The same recording film as the SO standard format medium cannot be used,
New multi-layer recording / reproducing film is required,
The enclosure is limited. [0006] As described above, conventionally,
Reduce the recording pit diameter of the recording medium for density recording
In this case, the diameter of the reproducing light spot is also reduced accordingly.
To accurately irradiate each recording pit with a light spot
It becomes difficult and cannot play high resolution
In addition, high-density recording is reproduced at high resolution.
What is considered to be produced is a magneto-optical recording medium.
Can only be applied to the body and has a limited range of use
I will. By the way, Japanese Patent Application Laid-Open No. 4-123341 is disclosed.
Have multiple spots within the light spot diameter using the magnetic field modulation recording method.
The recording pits are recorded, and the signal
Difference of magneto-optical effect caused by difference as difference of intensity
Multi-value reproduction by detecting and setting two or more thresholds
Are disclosed. However, Japanese Unexamined Patent Publication No.
Publication No. JP-A No. 10-27139, the irradiation of the reproduction light spot
This is done for each recording block containing multiple pits.
The recording track in the scanning direction of the track on the medium.
If locks are arranged continuously, blocks before and after
Intersymbol interference from the pits of the
It becomes impossible to reproduce the data. Therefore, each block
Data between the light spot diameters.
A gap area that is not recorded is provided to ensure that each light spot is recorded.
Prevent mutual interference by supporting recorded blocks
In this way, there is a gap area
Reduces the efficiency of use of the media,
Due to discontinuity, the timing for recording and reproducing data
It is difficult to control the complicated recording and playback timing.
There is a problem that a step is required. [0009] The present invention has been made in view of the above circumstances.
With this, high-density recording information can be
Optical information reproduction that can be easily reproduced with high resolutionMethod
The purpose is to provide. [0010] Means for Solving the Problems The present invention provides:Disk note
Are arranged at a predetermined pitch along the recording track of the recording medium.
Light spot on recorded information consisting of recorded pits and unrecorded pits.
The disk-shaped recording medium is rotated by rotating the disk-shaped recording medium.
The recorded information is detected by detecting the reflected light of the light spot.
An optical information reproducing method adapted to read
Spots are recorded on the same recording track and are adjacent
Of at least two recording pits at the same time
And the detection of the reflected light is performed at every predetermined pitch.
The light level is detected, and from the light level
The recording pits irradiating the light spot and
When determining the arrangement state of unrecorded pits,
The recorded pits and the unrecorded pits at the predetermined pitch
It is determined based on the arrangement of the units. [0011] As a result, according to the present invention, the recording of the recording medium
Recording pits that are arranged at a predetermined pitch along the rack
Light spots are recorded for recorded information consisting of recording pits
Array pitch of the recording information in the scanning direction along the track
Recording pits in the light spot when moving
Detecting the level of the playback signal that contributes
To detect the number of recording pits from
Playback signal contributed by recording pits present in the light spot
Move based on the arrangement of recording pits determined from the level.
I try to guess the arrangement of the recording pits after the movement starts
You. Thus, the recording pitch for high-density recording is obtained.
The light spot diameter can be increased
Light spots on the recording pits.
Accurate irradiation and high-resolution reproduction for high-density recording
Can be realized. Also, it is necessary to make the recording data discontinuous.
The efficiency of media usage,
It is easy to set the timing when recording and reproducing data.
Also, according to the number of recording pits existing in the light spot,
By detecting changes in the playback signal level,
Without limitation, magneto-optical media, phase change media, dyes
Widely applicable to media materials such as media and uneven media
You. [0013] Embodiments of the present invention will be described below with reference to the drawings.
You. (First Embodiment) FIG. 1 is a schematic diagram for explaining a first embodiment.
It is a reminder. In FIG. 1A, reference numeral 1 denotes a recording medium.
Of the recording medium 1 is based on the presence or absence of a physical change as recording information.
The recorded pit 2a and the unrecorded pit 2b
They are formed in a line at a predetermined pitch along the hook 1a. Then, these recorded pits 2a and unrecorded
Recording track 1a on the surface of the recording medium on which the slot 2b is formed
The reproduction light spot 3 is scanned relative to the direction.
I'm trying. In this case, the diameter of the light spot 3 is
It is possible to simultaneously store two recording pits 2a in the pot 3.
It is set to the size that can be. In other words, the light in this case
The size ratio between the spot 3 and the recording pit 21 is, for example,
l / e^Two The diameter of the light spot 3 defined by
Then, the diameter of the recording pit 2b is set to about 0.3 of 1/3 thereof.
It is set to 5 μm. In this state, the light spot 3
t₀ , T₁ , T_Two , T_Three , T_Four , T_Five In, each
3a, 3b, 3c, 3d, 3e, 3f
Is being inspected. FIG. 2 shows such a light spot 3.
1 shows a schematic configuration of an optical system. In this case, the laser
Light emitted from the ion 21 is collimated by the collimator 22
Converts the beam into parallel light, and forms a beam shaping prism and beam splitter.
The light is converted into a circular light beam by the
A minute light spot on the recording medium 25 through the
You. On the other hand, the light reflected from the recording medium 25 is again reflected by the objective lens.
Beam forming and beam splitter 23 through
Given, reflected at the junction surface here, the photodiode 2
6 to obtain an information signal by photoelectric conversion, and an information reproducing circuit 27
To perform signal reproduction processing. Thus, in FIG.
Time 3 at time t₀ To t_Five 3a, 3b, 3c, 3 shown in
When scanning is performed at each position of d, 3e, and 3f, each scan is performed.
A reproduction signal at the pot position is obtained.
Has its level changed as shown in FIG.
You. That is, the level of the reproduced signal in this case is L₁ , L
_Two, L_Three Takes three values. The reason is that the recording pit 2a is used as a reproduction signal.
The following three states that can contribute
It is. (A) When the number of recording pits 2a in the light spot 3 is zero. (B) A recording pit 2a is formed in the light spot 3.
If there is one. (C) Two recording pits 2a exist in the light spot 3
Case. In this case, the degree to which the recording pit 2a contributes to the reproduction signal is
(C), (B), (A) in order of magnitude, the size is light
Since it is proportional to the number of recording pits 2a in the spot 3,
The playback signal level is L_Three , L_Two , L₁ In the order of
Becomes smaller). In FIG. 1B, at time t_Four But (A)
State, t₁ , T_Two , T_Three , T_Five Is the state of (B), t₀
Shows the state of (C). Where the playback signal level
Is L_Two Is at time t₁ Like the state of
When the recording pit 2a is on the left side in the light spot 3,
Time t_Two As shown in the state of FIG.
There are two possible cases when they are on the right side of
Can be inferred from the state of the playback signal level before and after
You. As a result, L₁ , L_Two , L_Three Asked as
3 types of reproduction signal level and left and right in light spot 3
It is determined from the result of determining which recording pit 2a exists.
The recorded information on the recording medium 1 can be read. FIG. 3 shows that L₁ , L_Two , L_Three age
Recording information from three types of reproduction signal levels
2 shows a schematic configuration of a generated recording information reproduction processing unit. This
In the case of, the reproduction signal 31 is an optical signal as described with reference to FIG.
Spot 3 is at time t₀ , T₁ , T_Two , T_Three , T_Four , T_Five
And indicated by 3a, 3b, 3c, 3d, 3e, and 3f, respectively.
To the signal position shown in FIG.
Given as a bell. The reproduced signal 31 is shown in FIG.
It is provided to a clock demodulation circuit 32 and a level discrimination circuit 35.
You. The clock demodulation circuit 32 synchronizes with the reproduction signal 31.
The clock is demodulated by the
To the light source driver 33. When pulling in synchronization
For example, using a synchronization pattern recorded in advance on a medium
Do. The light source driver 33 generates the reproduction light spot 3.
The light amount of the light source 34 to be generated is changed in synchronization with the clock.
Like that. FIG. 4 shows the timing of the change in the amount of light at the light source 34.
In this case, the light source 34 outputs the reproduced signal 31
Time t synchronized with₀ , T₁ , T_Two , T_Three , T_Four , T_Five of
Low light quantity so that high light level M2 can be obtained at the timing
So that level M1 and high light level M2 change alternately
are doing. On the other hand, the reproduced signal 31 is supplied to a level discriminating circuit 35.
Given to. The level discriminating circuit 35 is shown in FIG.
From the reproduced signal 31 whose level changes as shown in FIG._Three , L
_Two , L₁ Are to be detected. And les
The reproduction signal level detected by the bell discrimination circuit 35 is
The data is supplied to the bin 36 and is generated as binary data 37. In this case, the time t shown in FIG.₀ , T
₁ , T_Two , T_Three , T_Four , T_Five In the same figure
When the reproduced signal of each level as shown in FIG.
Then, first, time t₀ At level L_Three Output playback signal
Then, the decoder 36 outputs two records in the light spot 3.
It is determined that the recording pit 2a exists, and the binary data of "1, 1" is determined.
Data 37 is obtained. Next, at time t₁ At level L_Two Is output
And such a reproduced signal level is L_Two State is
Recording when the recording pit 2a is on the left side of the light spot 3
Two cases when the pit 2a is on the right side in the light spot 3
Therefore, the determination by the decoder 36 is based on the signal levels before and after that.
A logic circuit inferring from the bell
U. Time t₁ The playback signal level is L_Two What
State in which one recording pit 2a exists in the light spot 3
It is. • One clock of the minimum clock in the past (time t₀ )
Signal level is L_Three So time t₀ Then light spot
In this state, there were two recording pits 2a in the recording 3. Time t₀ Then, on the right side in light spot 3
Recording pits 2a are simultaneously recorded at time t₁ Light spot 3
It is also the left recording pit 2a. ・ Therefore, time t₁ Then, on the left side of the light spot 3,
The state 2a is present. With such logic, the decoder 36
Is the time t₁ Recorded only on the left side of light spot 3
It is determined that the pit 2a exists, and the binary data of "1, 0" is determined.
Data 37 is obtained. Next, at time t_Two At level L_Two Is output
And also in this case, the reproduced signal level is L_Two State is
Recording when the recording pit 2a comes to the left in the light spot 3
Two cases where the pit 2a comes to the right in the light spot 3
Therefore, the determination by the decoder 36 is based on the signal levels before and after that.
Guess from the bell ・ Time t_Two The playback signal level is L_Two So light spot
3, one recording pit 2a exists. The last one clock of the minimum clock
Time t₁ ) Is L_Two So time t₁
Shows that there is one recording pit 2a in the light spot 3.
It was state. Time t₁ Then, on the right side in light spot 3
The unrecorded pit 2b at the time t_Two Light spot in
This is also the unrecorded pit 2b on the left side in FIG. ・ Therefore, time t_Two Then, the recording pit on the right
The state 2a is present. With such logic, the decoder 36
Is the time t_Two Recorded only on the right side of light spot 3
It is determined that the pit 2a exists, and the binary data of "0, 1" is determined.
Data 37 is obtained. Hereinafter, another time t_Three , T_Four , T_Five about
Similarly, by applying the above guess,
The presence of the recording pit 2a in the recording medium 3 is determined, and the recording medium 1
The above recorded information is read. It is to be noted that the reproduction signal discrimination by the decoder 36 is
Guess is that the playback signal level is initially L_Three More light spot
The presence of the recording pit 2a in the unit 3 is determined, and
Optical spots for subsequent playback signal levels based on
To determine the presence of the recording pit 2a in the
Therefore, in the determination of the actual reproduced signal,
The signal level is L_Three To L_Three 1 block between
And decode the reproduced signal of this block.
The determination in the step 36 is performed. Next, regarding the decoder 36, the modulation method and
5, 6, 7, and FIG.
8 will be described. FIG. 5 corresponds to the reproduction signal level.
9 shows a conversion table of data before decoding. in this case,
The positional relationship between the light spot 3 and the recording pit 2a is shown in FIG.
As shown, there are two recording pits 2a in the spot 3.
L in the state_Three , One on the left side in spot 3
L_Two (Left), one on the right side of Spot 3
L_Two(Right), recording pit 2a exists in spot 3.
L without state₁ There are four possible states. But play
The signal level is L_Two (Left) and L_Two (Right) is the same size
That's it. Then, the recorded pit portion is 1, the unrecorded pit portion
Is 0, the data in each state is represented by the conversion table shown in FIG.
It is clear from the relationship in FIG.
You. Next, FIG. 6A shows n bits of a data string.
The reproduction level that the eye's reproduction level can take in the (n + 1) th bit
FIG. 3B shows the arrangement of the device until it is further regenerated.
Then, the reproduction state of the n-th bit can be obtained by the (n + 1) -th bit.
FIG. However, as described above, the reproduction state L_Three
To L_Three Is decoded as one block unit
Assuming that the array in the playback state is L_Three Starting from
FIG. 7 shows the conversion tables of FIGS. 6A and 6B.
Thus, there are five possible routes from (a) to (e).
Here, for example, when the route of (a) is taken, L_Three From
Start L_Two (Left), L₁ , L₁ , ..., L₁ , L_Two (
Right). Also, if you take the route of (b)
If L_Three Starting from L_Two (Left), L₁ , L_Two(Right) and
It becomes an array called. Hereinafter, the routes of (c), (d), and (e)
Are also represented by an array as shown in the figure. In this case, the routes of (a) and (b)
L after_Two (Right) is the L existing in the paths of (c) and (d).
_Two (Right), and the last L of the route of (d)_Two (
Left) is the L existing in the route of (a)._Two Return to (left)
And Then, L_Three (C) or (e) ending with
One block is completed when the route of_Three Or
It takes an array that starts with Using FIG. 5,
FIG. 8 shows the reproduction state of the data converted into data.
You. 8 (a) to 8 (e) correspond to FIG. 7 described above.
(A) to (e) respectively. For example, in FIG.
Raw state is L_Three And the corresponding data from Figure 5
Since it is “1,1”, (1) in FIG. 8 becomes “1,1”.
You. Also, L_Three Playback state L following_Two (Left)
The corresponding data is similarly "1,0" from FIG.
Therefore, (2) in FIG. 8 is "1, 0". Here, FIG.
The data 1 on the right of (1) and the data 1 on the left of (2)
Since data is duplicated, the data on the right side of (1) is
The data on the left side of (2) is discarded. (Or not shown
Makes the data on the left of (1) valid and the data on the right of (2)
Data may be discarded. Here, the playback state L_Three
To L_Three Is decoded as one block unit
Therefore, the leading blank data is regarded as 1 and the
Obtaining an information sequence on a medium as shown in (4) of (a)
Can be. FIGS. 7B to 7E are also described above.
8 (b) to 8 (e), respectively.
You can get information. In addition, L used here_Three From
L_Three Up to one block.
Needs to store data before decoding in memory
Therefore, if the block length is large, the load on the memory capacity will be large.
It becomes. Therefore, for example, between the maximum inversions of the NRZ encoding method
Improved shortcomings such as large gap, large DC and low frequency components
Using the I-NRZ-I system and other systems
This makes it possible to reproduce information with a small load on peripheral circuits.
You. In the above description, L_Three To L_Three Up to one block
, But is not limited to this. For example, L
₁ To L₁ Up to one block.
is there. Also, the clock signal is recorded in advance
By using the sample servo type medium,
The reference clock is extracted from the change in the amount of reflected light, and
Raw signals can also be synchronized. Therefore, in this way, the light spot 3
Can accommodate two recording pits 2a at the same time
Light spots at the scanning positions at each time.
Playback signal contributed by the recording pit 2a existing in the unit 3
Estimate the arrangement of the recording pits 2a from the level and record information
Is decoded, so that the recording pitch is
The diameter of the light spot 3 to some extent even if the diameter of the
The size of the recording pit 2a.
High-density recording
High-resolution reproduction can be realized for recordings. Also, the light spot 3 is moved one recording peak in the scanning direction.
The recording pitch existing in the light spot 3 when moved by the
The reproduction signal level to which the bit 2a contributes is detected, and this reproduction
When the number of recording pits 2a is detected from the signal level,
Then, the recording pit 2a existing in the previous light spot 3 is
Recorded pit average determined from the contributing playback signal level
The arrangement of the recording pits 2a this time based on the way
The effect of intersymbol interference is significantly reduced
Between the recording blocks as before.
Does not record data corresponding to the distance of the light spot diameter
The recording data is made discontinuous compared to the
Media usage efficiency,
And take timing when recording and reproducing data.
Control complex recording and playback timing
There is no need for any means. The recording pitch existing in the light spot 3 is
To detect a change in the reproduction signal level according to the number of
Therefore, the recording medium is no longer restricted,
Media, phase change media, dye media, uneven media, etc.
These recording media can be widely applied. The amount of light of the light source 34 is, for example,
Pit cycle from maximum playback power to almost zero light
Since it was changed synchronously, it was written as light spot 3.
The relative position with respect to the recording pit 2a changes continuously.
Data distortion due to inter-symbol interference, etc.
Can be suppressed. Also, the light source 34 is pulsed.
The flash emits light during playback compared to continuous flash.
The life of the light source can be extended by about twice or more. [0049](Reference example) FIG. 9 and FIG.Reference exampleIs a conceptual diagram for explaining
You. In this case, in FIG. 9, the shape of the light spot 3 is recorded.
Formed in a line along the recording track 1a on the medium 1.
The major axis is the column direction of the recorded pits 2a and the unrecorded pits 2b.
This is an example of an ellipse. In this way, the signal from the adjacent track
Suppresses crosstalk of information signals and spot displacement signals
So that the recording track direction, of course,
The distance between tracks can be reduced, and recording information
This enables high-density reproduction of information. In FIG. 10, the shape of the light spot 3 is shown.
Along the recording tracks 1a and 1b on the recording medium 1.
Recorded pits 2a and unrecorded pits formed in a row
The column direction of 2b is the short axis and the recording track 1a. Orthogonal to 1b
This is an example of an ellipse in which the direction is the major axis. In this way, the diameter of the light spot 3
Are located on recording tracks 1a and 1b adjacent to
Construct so that two recording pits 2a can fit simultaneously
To further increase the track density between tracks.
High-density reproduction of recorded information becomes possible. FIG. 11 shows an elliptical light spot on the recording medium 1.
FIG. 3 shows a schematic configuration of an optical system for providing a light source 3;
You. In this figure, only the outward optical system is shown. FIG.
And 71 is a laser diode.
Light emitted from the arm 71 is collimated by the collimator 72
The light is given to the polarization beam splitter 73. Soshi
The parallel light transmitted through the polarizing beam splitter 73
Is focused on a recording medium 75 via an objective lens 74 and directly
A light spot having a diameter of about 1 μm is formed. In this case, the laser diode 71
Fig. 12 shows the far-field pattern of the emitted light.
I have. Generally, the direction perpendicular to the junction of the laser diode
The divergence angle distribution 81 and the horizontal distribution 82 are represented by the full width at half maximum.
Asymmetric at about 25 degrees and about 10 degrees, respectively.
The cross section of the light beam after passing through the remeter 72 has an elliptical shape.
You. Therefore, the asymmetry of the intensity distribution in the light beam is taken into account.
And the effective NA of the objective lens 74 is
Since the direction perpendicular to the bonding surface of the medium 71 is large, the medium surface 7
The shape of the light spot on the laser diode 5 is
An elliptical shape with the minor axis in the direction perpendicular to the mating surface
Wear. (Second embodiment) FIG. 13 shows another example of the recording information reproduction processing unit described in FIG.
The same parts as those in FIG. 3 are denoted by the same reference numerals.
In this case, the reproduction signal 31 is set at time t.₀, T₁, T₂,
t₃, T₄, T₅Window to import in sync with
Is generated. By doing so, the clock demodulation circuit 32
Time t using the clock demodulated at₀ , T₁ , T_Two ,
t_Three , T_Four , T_Five Generated by the window generation circuit 38
The reproduced signal 31 is changed according to the window to be
5, the level determination circuit 35
The level of the reproduced signal in the
The decoding operation in the DA 36 can be performed accurately. (Third embodiment) The present invention can be combined with the magnetic field modulation recording method.
To achieve high density recording and high density playback at the same time
Can also. FIG. 14 shows a pickup smaller than the light spot diameter.
As a method of recording data, magnetic field modulation recording is performed on a magneto-optical recording medium.
FIG. 4 is a diagram around an optical system for explaining an example of performing recording. This
In the case of, 101 is a laser diode, this laser
Light emitted from the diode 101 is collimated by a collimator 102.
To collimate the light and give it to the polarizing beam splitter 103.
I can. Then, this polarization beam splitter 103 is transmitted through.
The passed parallel light is transmitted through the objective lens 104 to the magneto-optical medium 1.
05 to form a light spot with a diameter of about 1 μm
I am trying to. In this case, when recording information,
The optical power is adjusted so that the temperature of the medium 105 becomes higher than the Curie point.
And the magnetic head driver 106
The magnetic field of the head 107 is reversed at high speed in accordance with the recorded information.
You. At this time, the period of the recording pit depends on the reversal period of the magnetic field.
Only determined. On the other hand, the light reflected from the magneto-optical medium 105 is
Rotate the polarization plane by 45 degrees by passing through half-wave plate 108
S-polarized light reflectance and P-polarized light transmittance are both 100%.
Incident on the beam splitter 109 at an azimuth angle of 45 degrees,
Separates light in a direction. Then, the polarization beam splitter 109
The transmitted light is given to the lens 110 and the cylindrical lens 111 in order,
Generates astigmatism to the four-division photodiode 112
The output of the photodiode 112 is input to an arithmetic circuit
The focus error signal is obtained by processing at 113
You. On the other hand, the reflected light of the polarizing beam splitter 109 is recorded.
On a two-part photodiode 115 through a lens 114
The light is collected and the output of the photodiode 115 is calculated by an arithmetic circuit.
By processing at 113, a push-pull signal is obtained.
Further, the arithmetic circuit 113 includes the photodiodes 112 and 1
By performing a differential operation on the sum signal of the outputs of the 15
Output a signal. Next, according to such a magnetic field modulation recording method,
FIG. 15 shows the relationship with the present invention when pit recording is used.
This will be described with reference to (a), (b), and (c). In FIG.
116 indicates a change in the light amount of the light spot with respect to time.
In this case, the light level P is a constant value, and the recording surface
Is sized to reach above the Curie point temperature.
Have been. Also, in FIG.
For reversing the magnetic field directions N and S by 180 degrees according to the
Drive current of the magnetic head. Then, as shown in FIG.
The diameter of the recording pit 119 in the track direction with respect to
Magnetic field reversal half by magnetic head drive current 117
The period is set to be 1/3 or less of the diameter of the light spot 118.
And the recording pit 119 is recorded on the recording track.
120 is formed. As described above, in the magnetic field modulation recording method, the pit
Since the period is determined only by the magnetic field reversal period, the light spot
It is possible to record pits having a diameter of 118 or less.
High density recording / reproducing
Sometimes this can be achieved. The present invention is limited only to the above embodiment.
However, the present invention can be appropriately modified and implemented without changing the gist.
The present invention is not limited to the magnetic field modulation
Even when using the method, the light modulation pulse
By making the time short enough,
Pit recording is possible and can be combined with the playback method of the present invention.
By doing so, high-density recording and reproduction can be realized at the same time. In the above-described embodiment, the reproduction on the recording medium
Light spot diameter for recording and recording pits inside the light spot simultaneously
The size was set to fit two, but recording within the light spot
The number of pits is not limited to two, but three or more
It is also possible to use For example, if there are three,
The level of the reproduced signal shown in FIG.₁ , L_Two , L
_Three , L_Four Can take the following four values.
Recording media by developing logic circuits based on principles
The above recorded information can be read. For example, in a magneto-optical disk,
Divides each track into multiple sectors and maps each sector
As shown in FIG. 16, the preformat section 121 and the data section
122. Preformatting here
The unit 121 stores an address number and the like, and stores the data unit 1
Reference numeral 22 stores user data. And this
In such a magneto-optical disk, the pre-format unit 121
Is composed of uneven pits, and the data section 122
Magnetic recording is performed based on the principle of magnetism. The present invention
According to the raw format, it is recorded in such a different recording format
Pre-format section
Both 121 and data section 122 have higher density than before
Even if it is recorded by, it can be reproduced sufficiently. in this case,
The address part is not preformatted, but user data.
May be written at the same time. In other words, the address
Signals to be recorded in the preformat unit 121, such as
Is recorded according to the same recording principle as the user data. The reproducing method of the present invention is a multi-fan
Playback devices, that is, playback for multiple types of media
Applicable to any possible device. In this case, in one kind of medium
Signal recording principle in one case, two cases
In any case, signals from multiple types of media
At least two types of recording principles because they can be read
It is necessary to read out the signal of
Is compatible with any recording principle,
With a simple configuration, a multifunction device can be realized. As described above, according to the reproducing method of the present invention,
The amount of reflected or transmitted light between the recorded and unrecorded parts of the body surface,
If the medium is made of a material with different properties such as polarization state
For example, magneto-optical media, phase change media, dye media, uneven media
Such materials can be applied without limitation. Further, according to the present invention, the inner and outer peripheries of the recording medium are
And cut the clock frequency so that the pit diameters are almost equal.
It can be combined with the MCAV system to be replaced. MC
In the AV system, the same recording density as the innermost circumference in the CAV system is used.
Can be maintained over the entire circumference of the media.
It has the feature that it can be combined with the playback method of the present invention.
Higher density recording / reproduction is possible by matching
You. [0071] According to the present invention, the recording track of a recording medium is recorded.
Recorded pits and unrecorded at a predetermined pitch along the track
A light spot is recorded for the pit recording information.
In the scanning direction along the
Recording pits in the light spot when moving
The playback signal level to be detected, and
In addition to detecting the number of recording pits,
Playback signal level contributed by recording pits in the pot
Based on the arrangement of the recording pits
Because I guessed the arrangement of the recording pits after the start,
Even if the recording pit diameter is reduced for high density recording,
Record size can be maintained at a certain level.
Light spots can be accurately illuminated on the pits and high-density recording
High-resolution reproduction can be realized for recordings. In addition,
It is not necessary to make the recording data discontinuous compared to
With this, it is possible to increase the efficiency of using the medium,
It is easy to take the timing when recording and reproducing data.
Means for controlling complicated recording and playback timing.
There is also an advantage that it can be cut off. Also present in the light spot
Changes in the reproduction signal level according to the number of recording pits
Output, so there is no restriction on the recording medium,
Magnetic media, phase change media, dye media, uneven media, etc.
Widely applicable to various media materials.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram for explaining a first embodiment of the present invention. FIG. 2 is a diagram illustrating a schematic configuration of an optical system according to a first embodiment. FIG. 3 is a diagram illustrating a schematic configuration of a recording information reproduction processing unit according to the first embodiment. FIG. 4 is a diagram showing a timing of a light amount change in the light source according to the first embodiment. FIG. 5 is a diagram for explaining a decoder used in the first embodiment. FIG. 6 is a diagram for explaining a decoder used in the first embodiment. FIG. 7 is a diagram for explaining a decoder used in the first embodiment. FIG. 8 is a diagram for explaining a decoder used in the first embodiment. FIG. 9 is a conceptual diagram for explaining a reference example of the present invention. FIG. 10 is a conceptual diagram for explaining a reference example . FIG. 11 is a diagram illustrating a schematic configuration of an optical system according to a reference example . FIG. 12 is a diagram showing a far-field pattern of light emitted from a laser diode of the optical system of the reference example . FIG. 13 is a diagram illustrating a schematic configuration of a recording information reproduction processing unit according to a second embodiment of the present invention. FIG. 14 is a diagram showing a schematic configuration around an optical system of a magnetic field modulation recording system according to a third embodiment of the present invention. FIG. 15 is a view for explaining the relationship with the present invention when pit recording by a magnetic field modulation recording method according to a third embodiment is used. FIG. 16 is a diagram showing a format in the case of a magneto-optical disk as a recording medium. [Description of Signs] 1 ... recording medium, 2a ... recorded pits, 2b ... unrecorded pits, 3 ... light spot for reproduction, 21 ... laser diode,
22: collimator, 23: beam shaping prism and beam splitter, 24: objective lens, 25: recording medium,
26 ... photodiode, 27 ... information reproducing circuit, 31 ...
Reproduction signal, 32: clock demodulation circuit, 33: light source driver, 34: light source, 35: level determination circuit, 36: decoder, 37: binary data, 38: window generation circuit, 7
1: laser diode, 72: collimator, 73 ...
Polarizing beam splitter, 74: objective lens, 75: recording medium, 101: laser diode, 102: collimator, 103: polarizing beam splitter, 104: objective lens, 105: magneto-optical medium, 106: magnetic head driver, 107: magnetism Head, 108 ... 1/2 wavelength plate,
109: polarizing beam splitter, 110: lens, 1
11: cylindrical lens, 112: quadrant photodiode,
113 arithmetic circuit, 114 lens, 115 divided photodiode, 118 light spot, 119 recording pit.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-28499 (JP, A) JP-A-4-332919 (JP, A) JP-A-5-89470 (JP, A) JP-A-2- 9028 (JP, A) JP-A-3-16031 (JP, A) JP-A-6-282845 (JP, A) JP-A-3-242845 (JP, A) JP-A-5-342586 (JP, A) JP-A-63-302425 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B ^7/ 12-7/22 G11B 11/105

Claims (1)

(57) [Claims] [Claim 1] Along a recording track of a disk-shaped recording medium.
This means that recorded pits and unrecorded
A light spot is irradiated on the recorded information consisting of
Rotate the recording medium and detect the reflected light of the light spot
To read the recorded information.
In the information reproducing method, the light spot is recorded on the same recording track and
At least two adjacent recording pits fit simultaneously
The reflected light is detected by the predetermined pitch.
The light amount level is detected for each of the
The recording pit being irradiated from the light spot to the light spot
And when determining the arrangement state of the unrecorded pits, one
The recording pit at the predetermined pitch in front and the
Determined based on the arrangement of recording pits
An optical information reproducing method, characterized in that: