JP3274984B2 - Method for manufacturing optical disk master and optical disk exposure apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical disk master for manufacturing an optical disk for recording information and an optical disk exposure apparatus used for manufacturing the optical disk master.

[0002]

2. Description of the Related Art Conventionally, as a method for manufacturing an optical disk master, there is a method in which a recording frequency is changed for each zone of a plurality of tracks on a circular substrate having a constant rotation speed using an optical disk exposure apparatus. FIG. 5 shows the change of the recording frequency with respect to the radial position of the circular substrate of the disk exposure apparatus, and the recording frequency increases stepwise from the inner zone to the outer zone. In FIG. 5, the vertical axis indicates the recording frequency, the horizontal axis indicates the radial position, that is, the distance from the center of the optical disk to the exposed portion, and both the vertical and horizontal axes are arbitrary scales. In the above optical disc exposure apparatus, as shown in FIG. 6, the pulse length of the recording signal is a value determined by an integral multiple of the reciprocal T of the recording frequency, or a fixed fixed value irrespective of the zone and the radial position of the optical disc. And

As another method of manufacturing an optical disk master, there is a method of determining a pulse length of a recording signal so as to be inversely proportional to a radial position (see Japanese Patent Application Laid-Open No. 2-166519).

[0004]

However, in the method of manufacturing a master optical disc in which the pulse length of the recording signal is determined by an integral multiple of the reciprocal T of the recording frequency for each zone, the reproduction signal of the optical disc manufactured from the master optical disc is used. Since it is difficult to control the exposure of a circular substrate having a constant rotation speed so as to have the required characteristics, the optical disc manufactured from the master disc of the optical disc cut by the pulse length,
There is a problem that the waveform characteristics of the reproduced signal are poor.

On the other hand, in the case of an optical disk manufactured from a master of an optical disk cut with the above-mentioned fixed pulse length or an optical disk manufactured from a master of an optical disk cut with a pulse length inversely proportional to the radial position, the inner circumferential side is There is a problem in that the characteristics of the reproduced waveform vary between the zone of FIG.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a master optical disc and an optical disc capable of manufacturing an optical disc capable of improving characteristics of a reproduced waveform and reducing variations in characteristics of a reproduced signal between an inner zone and an outer zone. An exposure apparatus is provided.

[0007]

According to a first aspect of the present invention, there is provided a method of manufacturing an optical disk master, comprising: rotating a circular substrate having a resist coated on a surface thereof at a constant rotational speed; When irradiating the resist by irradiating with modulated light modulated based on the recording frequency, the recording frequency is changed for each concentrically divided zone of the circular substrate, and then the exposed resist is developed. Correcting the pulse length of a recording signal modulated on the basis of the recording frequency for each zone of the circular substrate, in accordance with the radial position of the circular substrate. Outputting an exposure light quantity data signal for controlling the exposure light quantity, and controlling according to the recording signal whose pulse length has been corrected for each zone and the radial position. On the basis of the optical light quantity data signal, it is characterized by a step of exposing by irradiating the modulated light to the resist of the disc substrate.

According to the method of manufacturing an optical disk master according to the first aspect of the present invention, the amplitude of a reproduction signal of an optical disk manufactured from the optical disk master, the mark / space ratio, and the like are converted into characteristics according to a reproduction circuit to be used. By correcting the pulse length and exposure light amount of the modulated light for each zone of the circular substrate so as to be able to read the reproduced signal without any change, and setting the appropriate pulse length and exposure light amount, the coating was performed on the circular substrate. Pits exposed on resist (recorded information)
Is optimally set for each zone. Therefore, it is possible to manufacture an optical disk having good reproduction waveform characteristics and little fluctuation in reproduction signal characteristics between the inner zone and the outer zone.

The optical disk exposure apparatus according to claim 2 is
2. An optical disk exposure apparatus used in the method of manufacturing an optical disk master according to claim 1, wherein a pulse for correcting a pulse length of a recording signal modulated based on a recording frequency for each concentrically divided zone of a circular substrate. A length correction unit, a radial position data unit that outputs a radial position data signal in accordance with a radial position of the circular substrate, and a radial position of the disk substrate that receives the radial position data signal from the radial position data unit. An exposure light amount setting unit that outputs an exposure light amount data signal that controls an exposure light amount according to the recording signal whose pulse length has been corrected by the pulse length correction unit, and the exposure light amount data signal from the exposure light amount setting unit. And an exposure unit for exposing a resist on the circular substrate rotating at a constant rotation speed based on

According to the optical disk exposure apparatus of the second aspect, the amplitude of the reproduction signal and the mark / space ratio of the optical disk manufactured from the optical disk master are set to the characteristics according to the used reproduction circuit and the like, and no error is caused. In order to read the reproduction signal, for each concentrically divided zone of the circular substrate, by correcting the duty of the recording signal modulated based on the recording frequency by the pulse length correction unit,
Set to an appropriate pulse length. Further, in response to the radial position data signal output from the radial position data section according to the radial position of the circular substrate, the exposure light amount setting unit controls the exposure light amount according to the radial position of the disk substrate. Output a signal. Then, based on the recording signal whose pulse length has been corrected by the pulse length correction unit and the exposure light amount data signal from the exposure light amount setting unit, the resist on the circular substrate rotated at a constant rotation speed by the exposure unit By exposing, the size of pits (recorded information) to be exposed on the resist applied to the circular substrate is optimally set for each zone. Therefore, an optical disk manufactured by using an optical disk master manufactured by using this optical disk exposure apparatus has good reproduction waveform characteristics and reduces variation in characteristics of reproduction signals between an inner zone and an outer zone. can do.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing an optical disk master and an optical disk exposure apparatus according to the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 1 is a schematic block diagram of an optical disk exposure apparatus used in a method of manufacturing an optical disk master according to one embodiment of the present invention, wherein 1 is a frequency generator for generating a recording frequency, and 2 is the frequency generator 1 described above. A recording information storage unit for receiving a signal from the storage unit and outputting a signal representing stored recording information (for example, track address information), and a signal from the frequency generator 1 and a recording from the recording information storage unit 2 The data encoder 4 receives the signal representing the information and modulates the recording information according to a predetermined modulation method. The data encoder 4 receives the signal from the frequency generator 1 and the modulated recording signal from the data encoder 3 and will be described later. A duty correction circuit that corrects the duty of the recording signal based on the duty correction signal and outputs the corrected recording signal. In the frequency generator 1, the recording frequency increases stepwise from the inner zone to the outer zone for each zone in units of a plurality of tracks.

Reference numeral 7 denotes a radial position data unit which receives a signal from the recording information storage unit 2 and outputs a signal representing the stored radial position data, and 8 denotes a radial position data unit from the radial position data unit 7. A zone information storage unit that receives a signal indicating data and outputs a signal indicating stored zone information;
Reference numeral 9 denotes a duty correction data unit that receives a signal representing the zone information from the zone information storage unit 8 and outputs a duty correction signal based on the stored duty correction data, and 10 denotes a radius from the radial position data unit 7. An exposure light amount data unit that receives a signal indicating position data and outputs a signal indicating the exposure light amount based on the stored exposure light amount data. Receiving the corrected recording signal from the duty correction circuit 4 and the signal indicating the exposure light amount from the exposure light amount data unit 10, the exposure light amount setting circuit 5 sets the exposure light amount and controls the optical disk exposure unit 6. Output a signal.

The duty correction unit 4, zone information storage unit 8 and duty correction data unit 9 constitute a pulse length correction unit.

In the optical disk exposure apparatus having the above-mentioned structure,
In synchronization with the recording frequency of the signal generated by the frequency generator 1, the recording information stored in the recording information storage unit 2 is modulated by the data encoder 3 into a recording signal to be written on an optical disk. The recording signal has a pulse length that is an integral multiple of the reciprocal T of the recording frequency. Further, upon receiving a signal representing the radial position data from the radial position data section 7, the zone information storage section 8 determines the zone of the optical disk and outputs a signal representing the zone information. A signal representing the amount of duty correction is output from the duty correction data unit 9 to the duty correction circuit 4 in accordance with the signal representing the zone information from the zone information storage unit 8. Then, the duty correction circuit 4 receives the signal from the frequency generator 1 and the recording signal from the data encoder 3, and corrects the pulse length of the recording signal based on the duty correction amount, thereby correcting the pulse length. The recording signal is output to the exposure light amount setting circuit 5. Further, in response to a signal indicating the radial position data from the radial position data section 7, the exposure light quantity data section 10 outputs an exposure light quantity data signal for controlling the exposure light quantity to the exposure light quantity setting circuit 5.
Output to The exposure light quantity setting circuit 5 receives the recording signal of which the pulse length has been corrected from the duty correction circuit 4 and inputs the exposure light quantity data signal to the optical disc exposure section 6 together with the recording signal. Then, the optical disc exposure section 6 performs the following based on the recording signal whose pulse length has been corrected from the exposure light quantity setting circuit 5 and the exposure light quantity data signal.
A disk substrate (not shown) rotating at a constant rotation speed is irradiated with modulated light for exposure. Note that a resist is applied to the surface of the disk substrate in advance.

Then, after developing the resist on the exposed disk substrate to form a pattern, a metal plate is formed on the disk substrate by electroforming, and the metal plate is peeled off from the disk substrate. Manufactures an optical disc master.

In the method of manufacturing an optical disk master using the above-described optical disk exposure apparatus, as shown in FIG. 2, a radial position representing a distance from the center of the disk substrate to the exposure position is determined.
The pulse length of the recording signal that is an integral multiple of the reciprocal T of the recording frequency is
Adjust within the range of the duty change amount. That is, the pulse length of the modulated light modulated on the resist on the disk substrate based on the recording frequency is corrected for each zone.

With the above optical disk exposure apparatus, quadruple density 3.5
A case of manufacturing an optical disk master for a type magneto-optical disk will be described below.

In the quadruple-density 3.5-type magneto-optical disk, 1-7 RLL (run-length limited) modulation is performed. Therefore, the pulse length of the recording signal in the optical disk exposure apparatus, excluding the sector mark signal, , The length is twice to eight times the reciprocal T of the recording frequency. Here, in a pattern having a pulse length eight times the reciprocal T of the recording frequency, even if the pulse length is changed by about the reciprocal T of the recording frequency, the signal amplitude of the reproduced waveform of the pattern of the long pulse hardly changes.

FIG. 3 shows a quadruple-density 3.5-type magneto-optical disk manufactured from the above-described optical disk master. 3 shows changes in the maximum value and the minimum value of the amplitude of the reproduction signal (2T signal) having a pulse length as short as twice the reciprocal T of the recording frequency with respect to the change in the duty correction amount. The duty correction amount on the horizontal axis in FIG. 3 is an arbitrary scale. As shown in FIG. 3, as the duty correction amount increases, the maximum value and the minimum value of the 2T signal amplitude gradually increase.

FIG. 4 shows a duty correction of a pattern recorded by a repetition signal having a pulse length of eight times the reciprocal T of the recording frequency on a quadruple-density 3.5-type magneto-optical disk manufactured from the optical disk master. It shows the change in the ratio of the length of the mark portion and the space portion of the reproduction signal of the pattern with respect to the change in the amount. FIG.
The duty correction amount on the horizontal axis is an arbitrary scale. As shown in FIG. 4, as the duty correction amount increases, the mark / space ratio gradually decreases.

As described above, according to the method of manufacturing the master optical disc, the amplitude of the reproduction signal and the mark / space ratio of the optical disc manufactured by the master optical disc are reproduced without error by making the characteristics according to the reproduction circuit used. In order to be able to read the signal, record the signal for each zone of the circular substrate.
The pulse length of the pit (recorded information) exposed on the resist applied to the circular substrate is adjusted by correcting the pulse length of the optical disc (the modulated light of the optical disc exposure unit 6) and setting the pulse length to an appropriate pulse length. Set optimally for each case.

Therefore, it is possible to manufacture an optical disk having good reproduction waveform characteristics and little fluctuation in characteristics of reproduction signals in the inner zone and the outer zone using the optical disk master.

In the above embodiment, a quadruple-density magneto-optical disk has been described. However, a double-density magneto-optical disk whose recording frequency changes for each zone and a phase-change disk (P
Regarding D), the method of manufacturing an optical disk master and the optical disk exposure apparatus of the present invention may be applied.

[0025]

As is apparent from the above description, the method of manufacturing an optical disk master according to the first aspect of the present invention comprises rotating a circular substrate having a surface coated with a resist at a constant rotational speed, thereby forming the resist on the circular substrate. When irradiating with modulated light that is modulated based on the recording frequency, the recording frequency is changed for each concentrically divided zone of the circular substrate, and then the exposed resist is developed to form a pattern. In the method of manufacturing an optical disc master to be formed, in each zone of a circular substrate, exposure light amount data for correcting a pulse length of a recording signal modulated based on a recording frequency and controlling an exposure light amount according to a radial position of the circular substrate. A signal on the disk substrate based on the recording signal whose pulse length has been corrected for each zone and the exposure light amount data signal controlled according to the radial position. It is intended to be exposed by irradiating the modulated light.

Therefore, according to the method of manufacturing an optical disk master according to the first aspect of the present invention, the characteristic of the optical disk manufactured by the optical disk master, the amplitude of the reproduction signal, the mark / space ratio, etc., depending on the reproduction circuit to be used. And then
The pulse length of the modulated light and the amount of exposure light are corrected for each zone of the circular substrate so that the reproduced signal can be read without error, and the pulse length and the amount of exposure light are appropriately set. In addition, it is possible to manufacture an optical disk having little variation in the characteristics of the reproduction signal between the inner zone and the outer zone. In addition, by setting the same pulse length correction amount for each zone where the recording frequency is constant, variations in the characteristics of the same zone can be reduced.

According to a second aspect of the present invention, there is provided an optical disk exposure apparatus used in the method of manufacturing an optical disk master according to the first aspect, wherein each of the plurality of concentrically divided zones of a circular substrate is provided. The pulse length correction unit corrects the pulse length of the recording signal modulated based on the recording frequency, outputs a radial position data signal from the radial position data unit according to the radial position of the circular substrate, and outputs the radial position data signal. In response, the exposure light quantity setting unit outputs an exposure light quantity data signal for controlling the exposure light quantity according to the radial position of the disk substrate, and the recording signal whose pulse length has been corrected by the pulse length correction unit and the exposure light quantity. Based on the exposure light amount data signal from the setting unit, the exposure unit exposes the resist on the circular substrate rotating at a constant rotation speed.

Therefore, according to the method of manufacturing an optical disk master according to the second aspect of the present invention, the amplitude of the reproduction signal and the mark / space ratio of the optical disk manufactured by the optical disk master are made to have characteristics according to the reproduction circuit to be used. For each concentrically divided zone of the circular substrate, the recording signal whose pulse length has been corrected by the pulse length correction unit and the exposure light amount data from the exposure light amount setting unit so that the reproduced signal can be read without error. By exposing the resist on the circular substrate rotating at a constant rotation speed by the exposure unit based on the signal, the size of the pit (recording information) exposed on the resist applied to the circular substrate is changed for each zone. Set optimally. Therefore, an optical disk manufactured by using an optical disk master manufactured by using this optical disk exposure apparatus has good reproduction waveform characteristics and reduces variation in characteristics of reproduction signals between an inner zone and an outer zone. can do. Further, in the optical disc, by setting the same pulse length correction amount for each zone where the recording frequency is constant, it is possible to reduce the variation in the characteristics of the same zone.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an optical disk exposure apparatus used in a method of manufacturing an optical disk master according to the present invention.

FIG. 2 is a diagram showing a change in a pulse length with respect to a radial position in a case where a duty change amount is provided for each zone in the optical disc exposure apparatus.

FIG. 3 is a diagram showing a change in a relative value of a reproduction amplitude of a signal shorter than a duty correction amount in the optical disc exposure apparatus.

FIG. 4 is a diagram showing a change in the ratio between the length of a mark portion and the length of a space portion of a reproduction signal of a signal recorded by a repetition signal having a longer pulse length with respect to a duty correction amount in the optical disc exposure apparatus. It is.

FIG. 5 is a diagram illustrating a recording method in which a recording frequency is changed for each zone in units of a plurality of tracks at a constant rotation speed of an optical disk in a conventional method for manufacturing an optical disk master.

FIG. 6 is a diagram showing a change in pulse length determined by an integral multiple of a reciprocal of a recording frequency with respect to a radial position in the method of manufacturing the optical disc master.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Frequency generator, 2 ... Recording information storage part, 3 ... Data encoder, 4 ... Duty correction circuit, 5 ... Exposure light quantity setting circuit, 6 ... Optical disk exposure part, 7 ... Radial position data part, 8 ... Zone storage part, 9: Duty correction data section, 10: Exposure light quantity data section.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B 7/26

Claims (2)

(57) [Claims] 1. A method according to claim 1, further comprising: rotating a circular substrate having a surface coated with a resist at a constant rotation speed, and irradiating the resist on the circular substrate with modulated light modulated based on a recording frequency. In the method of manufacturing an optical disc master for changing the recording frequency for each concentrically divided zone of the circular substrate and thereafter developing the exposed resist to form a pattern, for each zone of the circular substrate, Correcting a pulse length of a recording signal modulated based on a recording frequency; outputting an exposure light amount data signal for controlling an exposure light amount according to a radial position of the circular substrate; Irradiating the resist on the disk substrate with the modulated light based on the corrected recording signal and the exposure light amount data signal controlled in accordance with the radial position. And a step of exposing to light. 2. An optical disc exposure apparatus used in the method of manufacturing an optical disc master according to claim 1, wherein the recording signal is modulated based on a recording frequency for each concentrically divided zone of a circular substrate. A pulse length correction unit that corrects the pulse length of, a radial position data unit that outputs a radial position data signal according to the radial position of the circular substrate, and receives the radial position data signal from the radial position data unit, An exposure light amount setting unit that outputs an exposure light amount data signal that controls an exposure light amount according to a radial position of the disk substrate; and a recording signal whose pulse length is corrected by the pulse length correction unit and the exposure light amount setting unit. An exposure unit for exposing a resist on the circular substrate rotating at a constant rotational speed based on the exposure light amount data signal of the optical disk. Apparatus.