JPS6243839A - Disc recording medium and its manufacture device - Google Patents

Abstract

PURPOSE:To attain high density of recording information without incurring deterioration of information quality by displacing an opposite ridge of an information recording groove in the groove width direction according to an information signal having a frequency belonging to the frequency band at the out-band of the servo control frequency and taking a multi-value level. CONSTITUTION:A spiral thin film recording groove 13 is provided and an information signal having a frequency belonging to the frequency band at the out- band of the servo control frequency in the tracking servo control system and taking a multi-value level is recorded with the displacement in the groove width direction based on a prescribe displacement of the opposite ridge of the information recording grove. Then, the information signal is obtained with excellent linearity from a push-pull signal obtained by receiving a read optical beam through the scanning of an information recording groove at a couple of photodetectors provided in parallel and obtaining the difference of outputs of both photodetectors in the read output, while being distinguished from a tracking error signal required in the tracking servo control system.

Description

[Detailed description of the invention] 1111 following the present invention! Please explain (-ro).

A Industrial Application Field 13 Overview of the Invention'ui ('Prior Art 1) The Invention Solved 7th'+Problem 1< Problem 1, 1, 1, 1, 1, and 1 to Solve 4-' Actions G Example G I Disc-shaped recording medium (FIGS. 1 to 4) 2 Disk-shaped recording medium manufacturing apparatus (5th [Me 1. A. Industrial Field of Application The present invention relates to a spiral-shaped recording medium in which a recording groove 4J surrounding the center rL of the center a is provided and a spiral-shaped recording groove surrounding the center rL. The information recording groove is connected to the disc-shaped recording medium manufacturing apparatus (65').

1. Overview of the invention One book produces two inventions.

One of the inventions #2 is a disk-shaped recording medium in which a recording section around a center a is provided with an information ψU recording path formed in a spiral shape surrounding a central hole and run by a reading light beam. C32 Oi゛(, information fI Jat! recording groove, its depth and lecture nt+) as hostage and -4 and and 4) i'
7. The information recording groove can read the opposite edge.
, which are formed when scanning by ,
The frequency belonging to the frequency band outside the servo 1st frequency band is
In response to the increasing level of information, information signals with multi-value levels can be produced relatively easily by making the angle (, predetermined change 1) ¥ to be displaced in the groove width direction. It can be recognized as having been recorded through a process that was not carried out, and
The readout signal obtained by scanning the information recording groove is received by a pair of light-receiving elements r provided at 1. (+
The read output of the fF level information signal is separated by 1x from the tracking caller signal so that it can be obtained with good or nearness 7, thereby:
Recorded information 1 yen #I secret! It was designed so that the following could be achieved.

The other of the two inventions is to make the light beam incident on the rotating recording surface and moving it in one direction perpendicular to the rotational tangential direction of the rotating recording surface. The optical beam 1 forms a spiral trajectory and is surrounded by a recording section in which an information recording groove having a substantially constant depth and groove width is formed according to the spiral trajectory, and the recording section is surrounded by the recording section. In an apparatus for manufacturing a disk-shaped recording medium that obtains a disk-shaped recording medium with a central center fL of 11, a beam incident on the C plane during rotational recording of 'C1 is deflected by an optical beam reciprocating deflection means in response to an information signal that takes a multi-value level. Multiple deflections of minute amplitudes! o1 Transcription The spiral locus formed on the upper surface is assumed to be displaced tFiν in a direction perpendicular to the r01 dynamic tangent direction of the rotating recording surface with a predetermined displacement example, and the frequency of the information signal that takes the above-mentioned polygon level is L racking servo disk 1 formed when an information recording groove formed on a disk-shaped recording medium is scanned by a reading light beam
By selecting a servo in a control system that belongs to a frequency band outside the control frequency band, it is possible to obtain a disk-shaped recording medium according to one of the above two inventions with a relatively compact configuration. There are some things I did.

0 On a disk as a conventional technical information recording medium, information 10 is recorded with a large number of pits arranged to form a spiral recording track, and the recorded information signal is reproduced on the first floor. A so-called optical disc was proposed in which a recording track was scanned by a light beam and changes in the arrangement of pits received by the light beam were detected to obtain a reproduced information signal. There is. In such optical discs, a large number of pits usually have a constant depth, and therefore, information signals are recorded as signals having 24 straight levels.

Such optical discs are often manufactured in large numbers, and for this reason, a master disc called a mask is created and the master disc is copied. To create a disc master, for example, a photoresist layer formed on a glass substrate with a polished plane is modulated by an information signal, which is a binary level signal, while the glass plate is rotated. The photoresist layer is then subjected to a development process to form an array of pits of a certain depth in accordance with the information signal, and further, A metal plating layer is provided on the surface thereof.

- In connection with the above-mentioned optical disc, the recorded information signal is replaced with a signal that takes a binary level, and is replaced by a signal that takes a ternary level or a multilevel level higher than that. It has been considered to increase the amount of information in a signal to obtain an optical disc with a higher density of recorded information. An information signal having such multiple levels, for example,
In order to obtain an optical disc on which an information signal having a ternary level is recorded, the master disc used for duplicating the information signal has a zero level as shown in FIG. 7A, for example.

3 of the positive level +a and the negative level -a (1tliIfI of FIG.
As shown in the plan view of FIG. 1 and FIG. 7C, after the photoresist layer 92 disposed on the glass substrate 91F is subjected to a development process, a plurality of pits p having two levels of depth are arranged. will be formed. That is, in this case, the photoresist layer 92 has a surface portion where p/ ) is not formed in response to the negative level -a of the information signal St, and a layer is removed from the surface portion in response to the zero level of the information signal St. A bin ip having a depth up to the middle part of the thickness is formed, and furthermore, the positive level +a of the information signal St
Correspondingly, a pit p having a depth D2 reaching from the surface portion to the surface of the glass substrate 91 is formed, thereby causing the photoresist layer 92 disposed on the glass substrate 91 to , pits p having two levels of depth corresponding to the zero level and positive level +a of the information signal St are formed. Incidentally, as shown in FIG. 7C, the pits p formed in the photoresist layer 92
The width also changes depending on the depth, and the width of the pit p having a larger depth D2 is larger than the width of the focus p having a depth Dl.

D Problems to be Solved by the Invention However, as mentioned above, multi-value levels, e.g.
In order to create a disc master for duplicating an optical disc on which an information signal St having a three-value level is recorded, a photoresist layer 92 disposed on a glass substrate 91 is coated with an information signal S (of a three-value level). In practice, various difficulties are involved in forming a pit p having two levels of depth depending on the size of the disc and in manufacturing a disc based on the created disc master.

That is, in order to be able to faithfully reproduce the information signal St that takes three levels from a disc that has been copied based on the original disc, the layers of the photoresist layer 92 must be When forming a pit p having a depth up to the middle part of the thickness, the depth Dl and width must be determined so that appropriate playback information (indication) can be obtained from the corresponding pit in the duplicated disc. : is required, so that for the photoresist layer 92 1.1-,,□
. 30. , □, □l? -A l: Yo, ya [
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This phase adjustment and control for the cyst layer 92 is J1.
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(ll-L Hell of 7L St) 1. It is easy to assume that the depth and shape of the pit for i. −
Obtaining with arity becomes 7 ability.

3(1^L・hell), the disk is 3(1^L・hell), and the 11 lehel+il of No. Suppose that the depth and shape of the pit with a certain value are 41, and the depth and shape of the pit are 41. Please read the information +jG' at times.
The boundary/motion of information is 'i-L7゛(L
, i ') and) will be changed to 'i').

This way, 1. c. ``Regarding the present invention, there are many
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1^1 wave number band ζ outside the 1 wave number band, '4 ro]? 11θ
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After that, it is relatively easy to set up a record hook (Ira rl, sequential at! record 1'/) 0 (l record r
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Informatization 5J, which takes the M level, is the oldest record. Il! record]
- To provide an iPi device capable of manufacturing a 4-disk-shaped recording medium having 114 and 114 digits based on a relatively simple configuration.
The purpose is 4.

In order to solve Problem 1I, step 1, the disk-shaped recording medium according to the invention is
The central hole and the d [! The recording section is provided with an information recording groove that is shaped like a spiral surrounding the central hole and is scanned by the C reading beam. ,re,
The 4t1 report recording groove is that tact and groove Φ! 11 is substantially constant, and the opposite edge thereof is assumed to undergo a predetermined displacement (+'7 more (displaced in the groove width direction) in response to an information signal having a multi-4+h level. Also, the above-mentioned U signal is a servo controller in the tracking servo control system ζ formed when the information recording groove is scanned by the reading optical beam J. It is assumed that 4- frequencies belonging to frequency bands outside the wave number band 1. to 1 are selected.

Further, the apparatus for manufacturing a disk-shaped recording medium according to the present invention includes a light beam 1, a light beam 1 from a light beam emitter 1 stage, and a light beam 1 from a light beam emitter 1 means to be incident on a rotating recording surface. , a path forming r step, and a light beam 1 formed by the light beam path forming means. A spiral trajectory is formed on the rotating recording surface 1-(!U
7) Optical beams 1 and i formed by the optical beam displacement means and the optical beam J and 1ffi path forming means
! In response to informatization-1, which is arranged in the JI circuit 1 and is incident on the rotating recording surface 1, multiple beams of light are incident on the rotating recording surface. The spiral locus is changed to the direction of the rotational tangent of the rotational recording surface by -2 by a predetermined amount of variation.
Reversal (-4) optical beam J, fliν deflection 1
◇Following the spiral spiral trajectory, the depth and groove width are substantially constant, and the opposite edge is a spiral trajectory. (i'!t
Recording medium formation to obtain a disk-shaped recording medium with a recording part in which a recording groove is not formed and a central hole surrounded by this recording part. The information recording groove formed in the disk-shaped recording medium is scanned by the reading optical beam 1, and the information as described above is formed when the information recording groove is scanned by the reading optical beam 1. −′
7. Servos in the Soking/9 Novo Control System 21) It is assumed that the servos in the servo control system belong to a frequency band outside the ol frequency band.

F Effect 1 - In the disk-shaped recording medium according to the present invention as described above, a spiral information recording groove t1 is provided, and a tracking servo is formed when this information recording groove is scanned by a reading light beam. An information signal that has a frequency that belongs to a frequency band higher than the servo control frequency band (for example, a servo control frequency band in a control system) and has a multi-value level is transmitted to a predetermined area on the opposite edge of the information recording groove. This means that the displacement in the original groove width direction is recorded as -. The multilevel information No. 18 written in the information recording groove in this way is read out by a pair of parallel light receiving elements that receive the reading light beam that scans the information recording groove. It is assumed that the push-pull signal obtained by determining the difference in the outputs of the light-receiving elements can be obtained with good or near accuracy, in distinction from the tracking error signal required in the trunking servo control system.

Therefore, the disk-shaped recording medium according to the present invention is provided with a recording track in which an information signal having a multi-sensitivity level is recorded through a process that is relatively easily carried out, thereby achieving a high density of recorded information. It becomes something.

In addition, in the disk-shaped recording medium manufacturing apparatus according to the present invention, the light beam is set to be incident on the rotating recording surface to form a spiral trajectory of the light beam on the rotating recording surface 1-, and the spiral trajectory is followed by a target. In order to obtain a disk-shaped recording medium provided with ζ-formed information recording grooves, a light beam incident on a rotating recording surface is deflected back and forth with a minute amplitude by a light beam reciprocating deflection means in accordance with an information signal having multiple levels. ,
The spiral locus formed on the rotating recording surface is reciprocated at a predetermined displacement position in a direction perpendicular to the tangential direction of rotation of the rotating recording surface, and the frequency of the information signal described in 1. A diary written on a recording medium! ! A tracking signal formed when the groove is scanned by a reading light beam; Selected to belong.

In this way, the frequency belonging to the frequency band outside the servo control frequency band in the tracking servo control system is formed when the spiral trajectory of the light beam formed on the rotating recording surface is scanned by the reading light beam. The light beam is reciprocated in a direction perpendicular to the tangential direction of the rotation of the rotating recording surface in response to an information signal that takes a multi-level level having By making it possible to obtain a disk-shaped recording medium provided with information recording grooves, the disk-shaped recording medium according to the present invention described in -F can be manufactured with a relatively simple structure. Ru.

G Example G-1 Disc-shaped recording medium (FIGS. 1 to 4) FIG. 2 generally shows an example of a disc-shaped recording medium according to the present invention.

In this example, a central hole lfJ< is provided, a recording section 3 extends around the central hole lfJ, and a label section 5 is further disposed between the central hole 1 and the recording section 3. In the recording section 3, an annular inner edge region 7 is provided on the inner circumference side, that is, on the boundary side with the leher section 5, and an annular outer edge region 9 is provided on the outer circumference side. Between the inner edge area 7 and the outer edge area 9, an information signal having multiple levels is recorded, and a light beam is made incident thereon to read the recorded information signal. This area is a recording track area 11 in which recording trunks are arranged.

In the recording track area 11, an information recording groove 13 formed in a spiral shape surrounding the central hole 1 is provided with a predetermined pinch to form a recording track. This spiral information recording groove 13 is formed on the surface -F of the substrate with a constant depth and a constant groove width, and is formed in the recording track area 11.
It is assumed that scanning is performed by a reading light beam during information reproduction in which information signals are read from the optical disc.

The disk-shaped recording medium shown in FIG.
, (The part in the recording area 11 of the body is written as shown in FIG. 1).

), (body!, N), the table 1h1 is tFt
The spiral information recording groove 13 has a depth t and a groove width W.
is constant and its opposite edge is 1^L
・Hell, for example, when taking the 3-sen level, there is a small amount of change ◇ according to the change in the height of 2. fljvT f r 'IR11'7 L, ,
Irregularities]ks M Formation of shi7wo-4ru4) (7) L phase ゛C exists. Pi t', as shown in Figure 3, as mentioned above, the 3 of the lower level (a) and the negative level -d.
411'In response to a change in the level of the signal S, one of the opposite edges of the information recording groove 1 (3) is shown as shown in FIG. However, information Igo issue S
t's zero lz<le, ++'-L"<le4a and I't
In response to L/<le a, people, W center equipment Po, base station PO to the outside of information record book 13, minute t)ti
1) Shifted convex portion 1 [shape forming device 11]
p, and J,% YII! (+'7 Minute h'tiii1fx on the inside of the information recording groove 13 from the position P o.
Only the skewer ti changed in U7 to form a concave part 4I>Placement 1> [1], and along with this 1, the information recording groove 1 (other than the opposite edge of 3) r', information +lI1. ：The zero of the number t・＼
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! :γ♂P゛() or C information record/#] Internal side of 3
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.

This J)41 L7-(,1Blue'tlJR+:S,Am
I: + is I'' 7h Ii, 1 w is kept constant and its opposite edges are, for example, λ is ゛, 3 I 1 ^ Lehel ↑ blue all old side -) 810 month.・＼Month・School 1
゜1-1u 'C1iik 小j; a蠀-も-7,
(Groove 111) J 1i11(,' fl iV is the line displacement L7, and the formation of a repetition of the unevenness 4.

In such a case, the ratio it of the minute \1i4fx to the groove ΦbjW is determined, for example, l/F (~l/fi culm).

Then, the slight change in the edge of the information recording groove 13 mentioned above (the amount of I is also increased), and the circumference 1 of U7, which repeats the unevenness of 2'C, is j Roni woman + 1. Iroji 4 Rumono to search 1 (Ori 1, '-'s love attack I non-verbal St's circumference θ■
(Ha, Yume Yu 11 o'clock (5' Oi (Joko U Record/J@ 1
3 is j? x
The 11-rule system ζ6r and (J-1)-1 ring are selected as belonging to the 15-wavelength band [15] from the 11-rule frequency band.

Therefore, the information recording groove 13 in the example shown in FIG. The servo-2 control frequency band, the L-3 signal having a frequency belonging to a higher frequency band [7. Note that the depth t of the information recording groove 13 is, for example,
The wavelength of 178 is selected.

When the thus formed recording groove 3 having unevenness on the opposite edge is scanned by the reading light beam, the reading light beam scans the recording groove 13 and reflects 2゛ζ. When a push-pull signal is received by a pair of light-receiving elements arranged in β and the difference in output between both light-receiving elements is calculated, the push-pull signal includes a low-frequency component 7 containing information I[i
The tracking number indicating the tracking state of the reading light beam lit in the recording groove 13 is rF f-
8 high-frequency components and (7), the amount of minute displacement of the opposing edge of the information 1υ recording course 13 is also calculated based on the unevenness of the
The read output of No. 4 8t will be included. The read output of the information signal S included in this pull signal 1 can be extracted by passing the current bus soiler and distinguishing 1 racking error 4A.

1- In order to obtain the substrate 14 on which the information recording groove 13 is formed as described above, in step-9, a disk master for duplicating it is developed on a glass substrate + four photoresist layers. Figures 1 and 31i
It is assumed that a groove similar to the information recording groove 13 formed on the surface ζ,' of the base body 14 shown in ZI B is formed. In other words, glass)! , the photoresist layer disposed on the plate 1- is coated with the information signal St by 1, 1-, groove' (, the depth and the groove width are constant -, and the opposite edge thereof corresponds to the level change of the information signal St Accordingly, the groove is displaced in the groove width direction by a small amount of displacement in the groove width direction, and a groove is formed in which the repeated unevenness 7 is formed.

In order to create such a groove with a constant depth, a light beam with a constant intensity is made to enter the photoresist layer on the glass substrate, and the incident position is changed according to the level change of information No. 18 St. The photoresist layer can be formed by performing exposure that changes accordingly, and then performing a development process on the photoresist layer. For this reason, difficult "depth control" of the photoresist layer is not required, and therefore a process that is relatively easy to carry out allows the photoresist layer disposed on the glass substrate to have depth control. A groove was formed in which the width of the groove was constant, and the opposite edges of the groove were displaced parallel to each other in the groove width direction with minute displacement violets in response to changes in the level of the information signal St, thereby forming repeated concavities and convexities. You can create a master disc, and then create the appropriate information recording groove 1.
3 can be easily obtained.

As a result, the information recording groove 1 formed in the base 14
Based on the fact that 3 is scanned by the reading light beam, the information signal that is reproduced I4: is obtained with good or near accuracy.

1. Substrate 14 shown in FIG. 1 obtained as described above.
As shown in FIG. 4, a disk-shaped recording medium having a thin reflective layer 15 is provided on the surface of the base 14 on which the information recording groove 13 is formed, and the reflective layer 1 is further provided with a thin reflective layer 15.
5-L is provided with a protective layer 17. reflective layer 1
5 is provided over the information recording grooves 13 formed in the base body 14 and the area between the information recording grooves 13, and therefore, the reflective layer 1
5 also forms a groove corresponding to the information recording groove 13. Further, the protective layer 17 is provided to fill the grooves of the reflective layer 15 and have a flat outer surface.

In the disk-shaped recording medium configured in this way,
A reading light beam is made incident from the base body 14 side, and the information recording groove 13 is scanned, and the base body 14 and the reflective layer 15 are scanned.
The readout light beam reflected at the interface with the receiver is received by a pair of parallel light receiving elements to form a push-pull signal, from which a tracking error signal and a readout of the information signal St are obtained. be done.

G-2 Manufacturing bag W for disc-shaped recording media (FIGS. 5 and 6) FIG. The main part of an example is shown below.

A laser light #21 is provided in a main part of this example of the disk-shaped recording medium manufacturing apparatus, and this laser light source 21 is composed of, for example, a helium neon laser or an argon laser.

After the laser light beam 22 made into a parallel beam from the laser light source 21 passes through the noise reducer 23 and the mirror 24,
The light beam is refracted by a lens 25 and made incident on a light beam deflector 26 .

On the other hand, a signal source 41 that generates an information signal having multiple levels, for example, an information signal St having three levels as described above.
is provided, and this information signal St is supplied to the control end of the voltage controlled oscillator 42.

The voltage controlled oscillator 42 is designed to generate, for example, a signal having a frequency centered at 200 MH2 and varying within a range of 200 MH2, ±20 MH2, and has a frequency of 200 MH2 ±20 MH2 at its output terminal in accordance with the information signal St. A frequency modulated signal Sa whose frequency is varied within a range of 2 is obtained. This frequency modulation signal Sa is transmitted to the amplitude adjustment section 43
After the amplitude is adjusted according to the control signal Ca from the terminal 44, the signal Ca is supplied to the amplitude modulation section 45, and the same! Periodic amplitude modulation is performed in accordance with the Ill signal Cs to produce a frequency modulated signal Sa'.

The frequency modulation signal Sa' is then supplied to the control terminal 26a of the optical beam deflector 26 via the amplifier 47.

The light beam deflector 26 is composed of an acousto-optic modulator, and is controlled by a frequency modulation signal Sa' supplied to a control terminal 26a, as shown in FIG.
an ultrasonic generator 51 that generates an ultrasonic wave having a frequency corresponding to the frequency of a'; a medium 52 that propagates the ultrasonic wave generated by the ultrasonic generator 51 to produce an acousto-optic effect; It includes an ultrasonic absorbing section 53 that faces the ultrasonic generating section 51 in between. As shown in FIG. 6, the laser beam 22 from the lens 25 enters the user 9 and the user 9 and the user 22a into the medium tX52. -C person 111 ShimeQ
) will be. This person 1. Luther's value, 22a, corresponds to the frequency modulation 14㎢S a ' (J)lil wave number 4-
1 wave number, tll ”), 2008M+1.+
2 +IMI+, the range of change depends on the ultrasonic wave whose wave number is
1. I'il rli 71.1. , ] Next Jtr
X 22 b The O-order light 22 CL, which is not diffracted, also has a predetermined diffraction angle 2θ of 12° (emitted from the medium 52).

The diffraction angle 2θ for the first-order diffracted light 22b is determined by the angle of incidence [
-The W:, L' -/-22aζ This wave 1 is λ, the frequency of the ultrasonic wave in the medium η52 is f, the propagation of the ultrasonic wave in the medium 'a52 ii! Degree as V? - Then, from Bragg Article no.
λ・f 2θ --- ■ C specified. Here, λ and V are constant r, 1
111 angle 2θ changes in proportion to 7.

The frequency f of the ultrasonic wave in the C3 medium 52 is 200M
I+□! t) varying in the range of 20MH2'
(The diffraction angle 2θ is the frequency fif of such an ultrasonic wave.
(7) 20 (IMII7-120MI+, l, i; L; '(change ゛4. The primary light emitted from the medium Y152) [Light 22b is an ultrasonic wave emitted) 1 part 51.
200M1l of wave number 1, change in range Q of '20M+12 1. At i4, U2, (to 1 direction, i, bottom, 1), and finally, the frequency modulation signal Sa' fed to the control end f26 a !, -1j is 1^l wave number major 4, minor 2. (, ( ,＜'
:Information from source 41 (No.4 stigoLi・,,(7) will be deflected. This deflection is
b, resulting in a tl'tν deflection with minute amplitude. , like 2, the information from 1 old name Ryo 41 (A No. S
After receiving the forward jν deflection with a minute amplitude corresponding to t,
In other words, the first-order refractor 22t) emitted from the medium rr52 of the 8-acoustic optical modulator constituting the deflector 26 is reflected by the lens 27f)? After twisting, pass only the first 101 fold "L22b" 4
"I: tl l Pass through 1 part 2B, and head towards mirror 29 as it turns to the front.

The first swept laser beam J, 22゛ is Mi ~ 29
, objective lens 32 via lens 30 and mirror 31 L2
The light is focused by the objective lens 32 and made incident on the C1 rotating recording medium 61.

The rotating recording medium 61 has a photoresist layer provided on a disc-shaped base to form a rotating recording surface, for example, and a turntable 63 that is moved 111 by a motor 62 has a central hole in its rotation axis. are mounted so that they match, and are rotated at a predetermined rotational speed.

With respect to such a rotating recording medium 61, the deflection direction of the deflected laser beam 22'' that has passed through the objective lens 32 is perpendicular to the rotation tangent direction of the rotating recording surface, that is, the diameter of the rotating recording medium 61. The lens 30, mirror 31, and objective lens 32 are moved integrally in the radial direction of the rotating recording medium 61 by, for example, the feeding movement section 64.
The incident position is gradually moved in the radial direction of the rotating recording medium 61, and the deflected laser beam 2 is placed on the rotating recording surface.
A 2° spiral trajectory is formed surrounding the central hole of the rotating recording medium 61 with a predetermined pitch. Note that the lens 30 is disposed to play a role of limiting the effective amount of the objective lens 32.

In this way, the swept laser beam 2 is formed with a predetermined pinch on the rotating recording surface of the rotating recording medium 61.
The spiral locus 11a1 of 2" has a constant width corresponding to the diameter of the deflected laser beam (2゛-), 22" on the rotating recording surface, and Based on the minute amplitude of the beam 22, and the reciprocating deflection,
It is assumed that the opposing edges are reciprocated with a minute amount of change in the direction perpendicular to the direction of deflection of the laser beam 22 to be deflected, that is, the rotation tangent direction of the rotating recording surface. This reciprocating change with a small amount of displacement of the opposing edge (◇ is the reciprocating deflection state of the deflected laser beam 22°, therefore, the signal source 4
It is assumed that the unevenness is repeated according to the waveform that takes the third level of the information signal St from 1 to 3. In this case, the pinch of such a spiral locus, the width, and the 1 law relationship between the unevenness of the opposite edge are approximately 2 to 3 times the width, and the unevenness of the opposite edge is An optical system for making the deflected laser beam 22° incident on the rotating recording surface of the rotating recording medium 61, and the lens 30, the mirror 31, and the edge lens 32 are integrated so that the amount of displacement is about 178 to 176 of the width. A feed drive unit 64 is set to move the rotating recording medium 61 in the radial direction.

Note that when the frequency modulation signal Sa' supplied to the control terminal 26a of the light beam deflector 26 is subjected to amplitude modulation by the synchronization signal C8 in the amplitude modulation section 45ζ, the light beam deflector 26 First-order diffracted light 22b emitted from
is assumed to have a change according to the synchronization signal Cs. Therefore, the deflected laser beam 22' has a change according to the synchronization signal Cs, and as a result, the rotating recording medium 6
Deflected laser beam 22 formed on the rotating recording surface of 1
The part corresponding to the synchronization signal Cs, Ill
Furthermore, the synchronization signal section is formed, for example, in an intermittent pattern. Since the rotating recording surface of the rotating recording medium 61 on which such a spiral trajectory of 22 degrees of the deflected laser beam is formed is formed of a photoresist layer, the photoresist layer has a spiral trajectory as described above. An exposure pattern having a shape locus is formed.

Thereafter, the recording medium forming means performs development processing and other processing on the photoresist layer on which the exposure pattern of the spiral locus has been formed, and the rotating recording medium 6
A protrusion or groove corresponding to the spiral trajectory of the deflected laser beam 22° is formed on the photoresist layer based on the rotating recording medium 61 on which the protrusion or groove is formed. A disk-shaped recording medium substrate is replicated, which is provided with a guide groove of constant depth and whose shape corresponds to a spiral trajectory.

In this way, the depth and width are made constant, and the opposing edges are reciprocated by repeated unevenness in the groove width direction having a predetermined displacement amount according to the information signal St from the signal source 41. Thus, a base body of a disk-shaped recording medium is obtained, which is provided with an information recording groove. The information recording groove provided in the base of such a disc-shaped recording medium will be scanned by a reading light beam after the disc-shaped recording medium is completed, but the depth of the groove is determined by the reading light beam, for example. It is assumed that this corresponds to 178 wavelengths of the beam.

Further, the information signal St from the signal source 41 described above has a frequency that belongs to a frequency band higher than the servo control frequency band in the tracking servo control system formed when the information recording groove is scanned by the reading light beam. It has been selected as a standard. Therefore,
The information recording groove provided in the base of the disk-shaped recording medium has a frequency that belongs to a higher frequency band than the servo control frequency band in the tracking servo control system that is formed when the information recording groove is scanned by the reading light beam. This means that the information signal St that has been written has been written.

Furthermore, by the above-mentioned recording medium forming means, a reflective layer is provided on the surface of the substrate obtained as described above, on which the spiral information recording groove is formed, and a protective layer is further provided on the reflective layer. A disk-shaped recording medium according to the present invention, whose cross section at the recording track portion is shown in FIG. 4, is obtained.

G-3 Modified Example Note that in the example of the disc-shaped recording medium according to the present invention described above, an information signal St having a level of 34I4 is recorded in the spiral information recording groove 13, and the disc according to the present invention Signal source 41 in an example of a manufacturing apparatus for a shaped recording medium
is said to generate an information signal St, and the disk-shaped recording medium according to the present invention has a spiral information record 8.
The information signal recorded in j/JI is not limited to one having a ternary level, but may be an information signal having a multilevel level of 4(i level or higher),
Further, - the signal aiii41 in the example of the disk-shaped recording medium manufacturing apparatus according to the present invention described above also generates an information signal having a multi-value level of 4-value level or higher, instead of the information signal St. I can do it.

i' H Effects of the Invention As is clear from the above explanation, the disk-shaped recording medium according to the present invention has a spiral information recording groove that is capable of storing multivalued information (No. 3 can be accomplished relatively easily). Information No. 11 was recorded with the Torino King "T-Bo"].
It is different from the Tofuno 4-ng/Ku-Iba issue that is required in the I/L system, and it is necessary to have good linearity. Therefore, according to the disk-shaped recording medium according to the present invention, the information on the evening of 41 (
In addition, the disk-shaped recording medium manufacturing apparatus according to the present invention has three features.
With a relatively simple structure, it is possible to reliably
It is possible to obtain a disk-shaped recording medium having a spiral information recording groove in which an information signal of 1^Level is recorded.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view showing a part of the base in an example of the disk-shaped recording medium according to the present invention, FIG. 2 is a plan view showing an example of the disk-shaped recording medium according to the present invention, and FIG. 4 to explain the information recording groove in the W body 1' shown in Figure 1.
FIG. 4 is an example of the disc-shaped recording medium shown in FIG. The .epsilon.'' section of an example of the manufacturing equipment is shown in Fig. 5.
1: An example of a disk-shaped recording medium manufacturing device manufactured by X? Fig. 7 is used to explain the manufacturing process of a conventional optical diff and deflector. is the center, 3 is the recording section, 13 is the information recording groove,
14 +; is a base, 15 is a reflective layer, 21 is a laser light source,
26 is a beam deflector, 32 is an objective lens, 41 is a signal source, 42 is an electric r+11iII 13I1 oscillator, [i
1 is a rotating recording medium. Listen-'dQ-

Claims (2)

[Claims] (1) A spiral information recording groove surrounding the central hole and scanned by the reading light beam is formed in the recording portion that extends around the central hole, and the information recording groove has a depth and a groove width. The opposing edges are displaced in the groove width direction by a predetermined amount of displacement in accordance with an information signal having a multilevel level, and the frequency of the information signal is set to be substantially constant. A disk-shaped recording medium that belongs to a frequency band outside the servo control frequency band in a tracking servo control system that is formed when a recording groove is scanned by a reading light beam. (2) a light beam generating means; a light beam path forming means for making the light beam from the light beam generating means incident on the rotating recording surface; and a light beam path formed by the light beam path forming means; a light beam displacement means for moving the light beam on the rotating recording surface in one direction perpendicular to the rotational tangent direction of the rotating recording surface to form a spiral trajectory of the light beam on the rotating recording surface; , which is disposed on the light beam path formed by the light beam path forming means, deflects the light beam back and forth with a minute amplitude in response to an information signal having a multilevel level, and deflects the spiral trajectory with a predetermined amount of displacement. a light beam reciprocating deflection means configured to reciprocate in a direction perpendicular to the rotation tangent direction of the rotation recording surface; a recording section in which an information recording groove is formed whose opposite edge is made to be substantially constant and whose opposing edge is displaced in accordance with the reciprocating displacement of the spiral trajectory; and a central hole surrounded by the recording section. a recording medium forming means for obtaining a disk-shaped recording medium having the following: a recording medium forming means for obtaining a disk-shaped recording medium having a frequency of the information signal formed when an information recording groove formed in the disk-shaped recording medium is scanned by a reading light beam; A manufacturing device for a disk-shaped recording medium selected to belong to a frequency band outside the servo control frequency band in a tracking servo control system.