JPH117647A - Exposure device for master optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a circuit for highly accurately forming an information pit in a master optical disk in an optimal shape and correcting a modulated signal from a signal modulator. SOLUTION: A signal modulator 21 outputs pulse modulated information to be written in an optical disk to a control circuit 22. This digital signal is extended by an OR circuit 31 and a delay element D0 and inputted to delay elements D1, D2,..., Dn and an AND circuit 32. A multiplexer 33 selects one of outputted signals from the delay elements D1, D2,..., Dn. A multiplexer 34 selects one from reference analog signals V1, V2,..., Vn. A switching element 35 is switched by a logical product signal outputted from the AND circuit 32, and the analog signal selected by the multiplexer 34 is switched ON/OFF. A pulse width detector 38 detects the pulse width of the digital signal inputted from the signal modulator 21 and, based on this detected signal, selection of one of the outputted signals from the delay elements D1, D2,..., Dn is performed by the multiplexer 33 and selection of one of the reference analog signals V1, V2,..., Vn is performed by the multiplexer 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk master exposure apparatus for exposing a photoresist master of an optical disk.

[0002]

2. Description of the Related Art The manufacturing process of an optical disc is roughly divided into the following.
The mastering process (mastering process) and the disc-making process (duplication of the optical disk by using a mold) are broadly divided, and the mastering process is divided into a mastering process and a premastering process.

[0003] The premastering step is a software preparation step in which information (recording data) to be recorded is created and edited in advance.

In the mastering step, a laser light obtained by optically modulating (digitally modulating) the recording data with an optical modulator such as an acousto-optic effect element is used to form a photo-sensitive material coated on a polished glass master. By exposing the resist film, the recording data is recorded (latent image recording pits are formed).

After the exposure, the photoresist film is developed,
After performing a predetermined process, information (recording pits) is transferred onto the surface of the metal by electroforming, and a metal stamper for duplicating an optical disk is formed using the information as a master. Then, optical disks can be mass-produced from the metal stamper.

[0006]

However, when information (recording pits) recorded on the optical disk manufactured as described above is reproduced, the intensity of a reproduced signal is generated depending on the length of the recording pits, and jitter is increased. Would. For example, in a write-once optical disc (CD-R), E is used for recording information.
FM modulation is used, and this modulation signal has a pulse width of 3T.
~ 11T (T is the basic clock of the CD signal;
1.4 nsec), and this modulation method is one in which a signal is long and jitter is easily generated.

Therefore, according to the standard defined for the write-once optical disc, when generating a write signal for compensating the waveform of an EFM reproduction signal, (n-
1) T-Strategy is proposed. This is because, for an EFM signal having a pulse width of nT (3T, 4T,..., 11T), the pulse width is reduced by 1T to (n-1) T, and a pulse width of an EFM signal having a pulse width of 2T is 50 nsec.
This is to make a correction for extension.

Japanese Patent Application Laid-Open No. 5-122027 discloses a technique in which correction according to the pulse width of EFM signals having different pulse widths is realized by a simple circuit.

According to this technique, a plurality of delay lines each having an analog delay amount corresponding to each pulse width of an input digital signal whose pulse width changes, and a gate signal are output near the terminal of the output of each delay line And a plurality of timing circuits which gate the outputs of the respective delay lines and output the same, thereby individually correcting digital signals having different pulse widths.

However, the technique proposed in the standard of the write-once optical disc described above is such that nT pulses other than the 2T pulse are uniformly set to (n-1) T. There is a problem that it is not a value.

On the other hand, the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 5-122027 does not uniformly treat nT pulses other than 2T pulses as (n-1) T. ) When the correction for extending the pulse is performed, the correction of the pulse having the other pulse width is performed by the above-mentioned n.
There is a problem that the pulse width is not flexibly corrected because it is limited to the extension of the pulse width in seconds or less.

Further, this conventional technique has a problem that the circuit configuration becomes complicated as the pulse width nT increases.

In addition, since this prior art does not have a function of detecting the pulse width T, the light amount of the laser beam to be exposed is corrected according to the pulse width, and information pits can be accurately detected. There is also a problem that it cannot be formed.

Accordingly, a first object of the present invention is to solve the above-mentioned problem and to make it possible to more flexibly correct the pulse width of a modulated signal by a signal modulator in accordance with the magnitude of the pulse width than in the prior art. An object of the present invention is to enable information pits to be formed in an optimum shape on an optical disk master.

A second object of the present invention is to adjust the light intensity of a laser beam to be exposed according to the pulse width of a modulation signal by a signal modulator, so that information pits can be formed with high precision. Is to do so.

A third object of the present invention is to make it possible to simplify a circuit for correcting a modulation signal by a signal modulator.

[0017]

According to a first aspect of the present invention, there is provided a light source for emitting a laser beam for exposing a photoresist master of an optical disk, and a signal of desired information to be recorded on the photoresist master is pulse width modulated. A signal modulator that converts the digital signal into a digital signal; a pulse width correction circuit that corrects the digital signal after the pulse width modulation to a desired pulse width that differs according to the magnitude of the pulse width; By turning on and off the irradiation of the laser beam to the photoresist master based on the pulse width, an optical modulator that turns the laser beam into an optical signal having a pulse width adjusted, and an optical modulator that emits the laser beam to the photoresist master And a position moving device for moving the irradiation position.

Therefore, after a signal of desired information to be recorded on the photoresist master is converted into a digital signal by pulse width modulation, the digital signal after the pulse width modulation is converted into a desired pulse width different according to the pulse width. Can be corrected.

According to a second aspect of the present invention, there is provided a light quantity correction circuit for correcting a pulse width modulated digital signal output from the signal modulator to a different pulse amplitude according to the pulse width. By turning on and off the irradiation of the laser beam to the photoresist master based on the pulse amplitude of the digital signal after the correction, the laser beam is converted into a light signal whose light intensity is adjusted. is there.

Therefore, by correcting the digital signal after the pulse width modulation to a different pulse amplitude according to the pulse width, the light intensity of the laser beam for exposing the photoresist master can be adjusted.

According to a third aspect of the present invention, when the pulse width of the digital signal after the pulse width modulation output from the signal modulator is relatively small, the pulse width of the digital signal is relatively reduced by the pulse width correction circuit. It is characterized in that the pulse width is corrected so that the pulse width of the digital signal is relatively reduced when it is enlarged and relatively large.

Therefore, when the pulse width of the digital signal after the pulse width modulation is relatively small, the pulse width of the digital signal is relatively enlarged, and when it is relatively large, the pulse width of the digital signal is relatively reduced. As a result, the pulse width can be corrected.

According to a fourth aspect of the present invention, when the pulse width of the pulse width modulated digital signal output from the signal modulator is relatively small, the pulse amplitude is relatively enlarged by the light amount correction circuit. When the pulse amplitude is relatively large, the pulse amplitude is corrected so that the pulse amplitude is relatively reduced.

Therefore, when the pulse amplitude of the digital signal after the pulse width modulation is relatively small, the pulse amplitude is relatively enlarged, and when the pulse amplitude is relatively large, the pulse amplitude is relatively reduced. Amplitude correction can be performed.

According to a fifth aspect of the present invention, the pulse width correction circuit comprises a first delay circuit for delaying the pulse width modulated digital signal output from the signal modulator by a fixed amount, and a digital signal after the pulse width modulation. A first OR circuit for outputting a logical sum signal of a digital signal and a digital signal obtained by delaying the digital signal by the first delay circuit; and a plurality of first OR circuits provided for each different pulse width of the digital signal after the pulse width modulation. A second delay circuit for delaying the logical sum signal according to the magnitude of the pulse width, and a logical product of the logical sum signal and a digital signal obtained by delaying the logical sum signal by the second delay circuit And a first AND circuit that outputs a signal.

Therefore, by adjusting the delay amount of each second delay circuit as desired, the digital signal after pulse width modulation can be corrected to a different desired pulse width depending on the magnitude of the pulse width.

In the technique disclosed in Japanese Patent Application Laid-Open No. 5-122027, a delay line, a timing circuit (such as a shift register) and an AND circuit are added each time the pulse width nT of a digital signal after pulse width modulation increases by 1T. Each of them must be increased by one, but in the present invention, it can be dealt with only by increasing the second delay circuits one by one.

According to a sixth aspect of the present invention, the light amount correction circuit selects one of a plurality of types of analog signals in accordance with the pulse width of the digital signal after the pulse width modulation output from the signal modulator. A signal selection circuit, a first switch for switching the selected analog signal with a logical product signal from a first AND circuit, and an amplifier for amplifying an output signal of the first switch. It is assumed that.

Therefore, the first signal selection circuit and the first
By correcting the pulse width-modulated digital signal to a different pulse amplitude according to the pulse width by the switch, the light intensity of the laser beam for exposing the photoresist master can be adjusted.

According to a seventh aspect of the present invention, there is provided a differentiating circuit for converting an output signal of the switch into a differential waveform and outputting the signal to an amplifier.

Therefore, by making the output signal of the switch a differential waveform and outputting it to the amplifier, the intensity of the optical signal can be increased at the front end and weakened at the rear end.

In a preferred embodiment of the present invention, the pulse width correction circuit frequency-modulates the pulse width modulated digital signal output from the signal modulator and adjusts the frequency according to the pulse width of the pulse width modulated digital signal. And a frequency modulation circuit for correcting the pulse width to a different desired pulse width.

Therefore, the digital signal after the pulse width modulation can be frequency-modulated and corrected to a desired pulse width different depending on the pulse width of the digital signal.

According to a ninth aspect of the present invention, in the frequency modulation circuit, when the pulse width of the digital signal output from the signal modulator after the pulse width modulation is relatively large, the frequency modulation circuit becomes relatively high in frequency. And frequency modulation is stopped when it is relatively small.

Therefore, when the pulse width of the digital signal output from the signal modulator after the pulse width modulation is relatively large, the frequency modulation is performed so that the frequency becomes relatively high, and when the pulse width is relatively small, the frequency modulation is performed. By stopping, when the pulse width of the digital signal after pulse width modulation is relatively small, the pulse width of the digital signal is relatively enlarged, and when it is relatively large, the pulse width of the digital signal is relatively reduced. As a result, the pulse width can be corrected.

According to a tenth aspect of the present invention, when the pulse amplitude of the pulse width modulated digital signal output from the signal modulator is relatively small, the pulse amplitude is relatively expanded by the light amount correction circuit. When the pulse amplitude is large, the pulse amplitude is corrected so that the pulse amplitude is relatively reduced.

Therefore, when the pulse width of the digital signal after the pulse width modulation is relatively small, the pulse amplitude is relatively enlarged, and when the pulse width is relatively large, the pulse amplitude is relatively reduced. Can be corrected.

According to an eleventh aspect of the present invention, in the frequency modulation circuit, a plurality of second switches for selecting and deselecting a clock signal for controlling the signal modulator by turning on and off, and the signal modulator include: A second signal selection circuit for selecting one of the clock signals output from the plurality of second switches in accordance with a pulse width of the digital signal after pulse width modulation to be output; And a second AND circuit that outputs a logical product signal of the digital signal output by the width modulation circuit.

Therefore, each second switch is turned on and off.
Then, the clock signal for controlling the signal modulator is selected or deselected, and the clock signal output from the plurality of second switches is selected according to the pulse width of the pulse width modulated digital signal output from the signal modulator. By selecting one of them and outputting a logical product signal of the selected clock signal and the digital signal output by the pulse width modulation circuit, the digital signal after the pulse width modulation differs according to the magnitude of the pulse width. It can be corrected to a desired pulse width.

According to the technique disclosed in Japanese Patent Application Laid-Open No. 5-122027, every time the pulse width nT of a digital signal after pulse width modulation increases by 1T, a delay line, a timing circuit (such as a shift register) and an AND circuit are added. Each of them must be increased one by one, but in the present invention, it can be dealt with only by increasing the second switches one by one.

According to a twelfth aspect of the present invention, the light amount correction circuit selects one from a plurality of types of analog signals in accordance with the pulse width of the digital signal after pulse width modulation output from the signal modulator. A third signal selection circuit, a third switch for switching the selected analog signal with a logical product signal output from the second AND circuit, and an amplifier for amplifying an output signal of the third switch. It is characterized by having.

Accordingly, the digital signal after pulse width modulation is corrected to a different pulse amplitude according to the pulse width by the third signal selection circuit and the third switch.
The light intensity of the laser light for exposing the photoresist master can be adjusted.

According to a thirteenth aspect of the present invention, a pulse for correcting a pulse width of a clock signal selected by a signal selection circuit in accordance with a pulse width of a digital signal output from a signal modulator after pulse width modulation. It is characterized by having a width control circuit.

Accordingly, the pulse width of the clock signal selected by the signal selection circuit can be further corrected according to the pulse width of the digital signal output from the signal modulator after the pulse width modulation.

According to a fourteenth aspect of the present invention, in the pulse width control circuit, a third delay circuit for delaying the clock signal selected by the signal selection circuit by a fixed amount, and the clock signal and the clock signal are supplied to the third delay circuit. A plurality of second OR circuits for outputting a logical sum signal with the digital signal delayed by the delay circuit, and a plurality of second OR circuits provided for each type of the clock signal, wherein the logical sum signal is subjected to pulse width modulation output from a signal modulator. A fourth delay circuit that delays according to the pulse width of the digital signal, and a third signal that outputs a logical product signal of the logical sum signal and the digital signal obtained by delaying the logical sum signal by the fourth delay circuit. And an AND circuit described above.

Therefore, by adjusting the amount of delay by each of the fourth delay circuits as desired, the digital signal after frequency modulation is converted into a digital signal according to the pulse width of the digital signal after pulse width modulation output from the signal modulator. Further corrections can be made.

[0047]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment of the Invention] In each of the following embodiments,
An example will be described in which a photoresist master of a hybrid type CD-R (a disc in which information is already written at the innermost periphery of a duplicated optical disc) of a write-once optical disc is exposed.

FIG. 1 is a block diagram for explaining the schematic arrangement of a master exposure apparatus 1 for forming latent image information pits on a glass master in a mastering step.

As shown in FIG. 1, a photoresist master 3 for exposure is mounted on the turntable 2. The photoresist master 3 is obtained by applying a photoresist film on a glass master. The turntable 2 (position moving device) is rotated by a spindle motor 4 (position moving device) driven by a spindle motor controller 7. The turntable 2 (position moving device) is disposed on a traverse stage 5 (position moving device), and the traverse motor 6 (position moving device) driven by a traverse motor controller 8 performs the traverse movement. It moves on the stage 5 in the horizontal direction (as indicated by the arrow in FIG. 1). Due to the rotation of the turntable 2 and the horizontal movement thereof, the exposure position on the photoresist master 3 moves spirally.

The Ar laser 11 is an exposure light source.
The laser light 12 emitted from the r laser 11 is reflected by a mirror 13, and an optical modulator 14 (an optical modulator such as an acousto-optic effect element) converts information to be written in the hybrid CD-R into an optical signal, and an objective lens 15. Converges on the photoresist master 3 to an extremely small light spot.

The signal modulator 21 is a hybrid type CD-
The information to be written in R is pulse-width modulated to an EFM signal, and the control circuit 22 (pulse width correction circuit, light amount correction circuit) performs pulse width correction and pulse amplitude correction on the EFM signal as described later. The optical modulator driver 23 turns on the laser light 12 by the digital signal after these corrections,
When turned off, the pulse width and intensity of an optical signal for forming information pits on the photoresist master 3 are controlled.

The pulse generator 24 outputs a reference clock (FPG) for controlling the signal modulator 21 and the like to the signal modulator 21, and outputs a clock signal (TPG) for controlling the spindle motor controller 7; 8 is output.

FIG. 2 is a block diagram showing a circuit configuration of the control circuit 22.

As shown in the figure, a delay element D0 (first delay circuit) is provided in the control circuit 22, and a digital signal input from the signal modulator 21 to the control circuit 22 is supplied to the delay element D0. Is entered. The output of the delay element D0 and the digital signal that does not pass through the delay element D0 are input to the OR circuit 31 (first OR circuit), and the OR signal of the two signals is output.

This OR signal is applied to delay elements D1, D2,
, Dn (second delay circuit) and AND circuit 32 (first AND circuit). Delay elements D1, D2,...
Each output side of Dn is connected to the multiplexer 33. The multiplexer 33 includes a delay element D
, Dn, and one of the output signals is selected, and the selected signal is input to the AND circuit 32.

The multiplexer 34 (first signal selection circuit) selects one signal from the reference analog signals V1, V2,..., Vn. The switching element 35 (first switch) is switched using the logical product signal output from the AND circuit 32 as a gate signal, whereby the analog signal selected by the multiplexer 34 is turned on and off. The differentiating circuit 36 makes the output signal of the switching element 35 a differentiated waveform, and the operational amplifier 37 amplifies the output signal of the differentiating circuit 36 and outputs it to the optical modulator driver 23.

From the signal modulator 21 to the control circuit 22
Is also input to a pulse width detector 38 provided in the control circuit 22. The pulse width detector 38 detects the pulse width of the digital signal input from the signal modulator 21 and outputs the detection signal to the multiplexers 33 and 34. By this detection signal, the delay element D1,
D2,..., Dn, and the reference analog signals V1, V2,.
.., Vn are selected.

Next, the operation of the master exposure apparatus 1 having the above configuration will be described focusing on the operation of the control circuit 22.

The pulse width modulated digital signal output from the signal modulator 21 by the delay element D0 and the OR circuit 31 is output as a logical sum signal whose pulse width is extended by a desired amount. Then, this OR signal is applied to each delay element D
1, D2,..., Dn, each of which is delayed by a desired amount, and one of the delayed signals is selected by the multiplexer 33 based on the detection signal of the pulse width detector 38. The AND circuit 32 outputs a logical product signal of the selected signal and a logical sum signal output from the OR circuit 31 and not passing through the delay elements D1, D2,..., Dn. As a result, the AND signal is output as a signal obtained by correcting the pulse width of the pulse width modulated digital signal output from the signal modulator 21 according to the magnitude of the pulse width.
The correction of the pulse width is performed so that the pulse width of the digital signal output from the signal modulator 21 after the pulse width modulation is enlarged when the pulse width is relatively large, and reduced when the pulse width is relatively small.

The reference analog signals V1, V2,.
Each of Vn is set to a desired voltage value, and one of them is selected by a multiplexer 34 based on a detection signal of a pulse width detector 38 and output to a switching element 35. The switching element 35 uses the logical product signal output from the AND circuit 32 as a base voltage and outputs the reference analog signals V1, V2,
, Vn, the pulse amplitude (voltage value) of the digital signal whose pulse width has been corrected as described above is corrected. The correction of the pulse amplitude is performed so that the digital signal output from the signal modulator 21 is enlarged when the pulse width is relatively large, and is reduced when the pulse width is relatively small.

As described above, the digital signal output from the signal modulator 21 is converted into a differential waveform by the differentiating circuit 36 after the pulse width and the pulse amplitude are corrected.
The signal is amplified by the operational amplifier 37 and input to the optical modulator driver 23. The optical modulator driver 23 drives the optical modulator 14 based on the input signal to turn on the laser light 12,
F. Laser beam 12 for exposing photoresist master 3
Of the optical signal by the optical modulator driver 23
The light intensity is controlled by the pulse width of the input signal to the optical modulator driver 23 according to the pulse width of the input signal to the optical modulator driver 23.

The delay elements D1, D2,..., Dn
, The pulse width of the optical signal for exposing the photoresist master 3 can be corrected as desired, so that the pulse width modulated digital signal output from the signal modulator 21 can be corrected. Can be more flexibly corrected than before, and information pits having an optimum shape can be formed on the photoresist master 3.

In addition, the above-mentioned Japanese Patent Laid-Open No.
In the technology disclosed in the above publication, the delay line, the timing circuit (such as a shift register) and the AND circuit must be increased by one each time the pulse width nT of the digital signal after pulse width modulation increases by 1T. In this embodiment, since it is possible to cope only by increasing the delay elements D1, D2,..., Dn one by one, the circuit configuration can be simplified.

Further, the pulse width of the output signal from the signal modulator 21 is detected by the pulse width detector 38, and any one of the voltage values from the reference analog signals V1, V2,. By selecting, the light intensity of the optical signal for exposing the photoresist master 3 can be adjusted, so that information pits can be formed with high precision.

Further, by providing the differentiating circuit 36, the input signal to the optical modulator driver 23 is made into a differential waveform, and the intensity of the optical signal for exposing the photoresist master 3 is increased at the front end and weakened at the rear end. Therefore, information pits can be formed with high precision.

[Second Embodiment of the Invention] The difference in the configuration and operation of the embodiment of the present invention from the first embodiment of the present invention lies in the control circuit 22. The configuration and operation of the control circuit 22 in the embodiment will be mainly described.

FIG. 3 shows a control circuit 2 according to this embodiment.
2 is a block diagram of a circuit configuration of FIG.

In the figure, circuit elements and the like having the same reference numerals as those in FIG. 2 are the same as those in the first embodiment of the present invention, and therefore detailed description is omitted.

In this embodiment, the delay elements D0, D
, D2,..., Dn, and the OR circuit 31,
The switches SW1, SW2,..., SWn in the control circuit 22
(A frequency modulation circuit and a second switch). ON, OF of these switches SW1, SW2,..., SWn
Depending on the state of F, the reference clock (FPG) is selected or deselected variously. And the multiplexer 33
(Frequency modulation circuit, second signal selection circuit) selects one of the digital signals generated by turning on and off the switches SW1, SW2,..., SWn.

In this embodiment, the differentiating circuit 36
Is not provided, and the output signal from the switching element 35 is directly input to the operational amplifier 37.

Next, the operation of the master exposure apparatus 1 having the above-described configuration will be described focusing on the operation of the control circuit 22.

The reference clocks (FPG) for controlling the signal modulator 21 include the switches SW1, SW2,.
Are variously selected and deselected according to the ON and OFF states of the. The switches SW1, SW2,..., SWn
One of the signals from is selected by the multiplexer 33 in accordance with the detection of the pulse width by the pulse width detector 38. The selected signal and the signal modulator 2
A logical product signal with the digital signal output by 1 is output from the AND circuit 32 (second AND circuit). This output signal is obtained by frequency-modulating the digital signal after pulse width modulation output from the signal modulator 21 in accordance with the detection of the pulse width by the pulse width detector 38, and the pulse width of the digital signal is corrected. You. That is, the correction of the pulse width by the frequency modulation is performed such that when the pulse width of the pulse width modulated digital signal output from the signal modulator 21 is relatively large, the pulse width is reduced by performing the frequency modulation. When it is extremely small, frequency modulation is not performed.

The switches SW1, SW2,...
By setting the ON and OFF states of SWn as desired, the pulse width of the optical signal for exposing the photoresist master 3 can be corrected as desired. The digital signal can be corrected more flexibly than before, and an information pit having an optimal shape can be formed on the photoresist master 3.

In addition, the above-mentioned Japanese Patent Laid-Open No.
In the technology disclosed in the above publication, the delay line, the timing circuit (such as a shift register) and the AND circuit must be increased by one each time the pulse width nT of the digital signal after pulse width modulation increases by 1T. In this embodiment, the switches SW1, SW2,.
Can be dealt with only by increasing the number one by one, so that the circuit configuration can be simplified.

As in the first embodiment, the light intensity of the optical signal for exposing the photoresist master 3 is controlled by the multiplexer 34 (third signal selection circuit) and the switching element 35 (third switch). Can be adjusted,
Information pits can be formed with high precision.

[Third Embodiment of the Invention] The control circuit 22 also differs from the second embodiment in the configuration and operation of the embodiment of the present invention. The configuration and operation of the control circuit 22 in the embodiment will be mainly described.

FIG. 4 shows a control circuit 2 according to this embodiment.
2 is a block diagram of a circuit configuration of FIG.

In the figure, circuit elements and the like having the same reference numerals as those in FIG. 3 are the same as those in the second embodiment of the present invention, so that detailed description will be omitted. This embodiment is different from the control circuit 22 of the second embodiment in that the pulse width control circuit 4
1 is added to the circuit configuration.

FIG. 5 is a block diagram showing a circuit configuration of the pulse width control circuit 41.

As shown in the figure, the pulse width control circuit 41
Are delay elements D00, D10, D20,..., Dn0, OR
A circuit 42, a multiplexer 43, and an AND circuit 44 are provided.

The delay element D00 (third delay circuit)
The signal selected by the multiplexer 33 is input. The output signal of the delay element D00 and the signal selected by the multiplexer 33 and not input to the delay element D00 are input to the OR circuit 42 (second OR circuit). A sum signal is output. , Dn0 (fourth delay circuit),
Each of the OR signals is input to an AND circuit 44 (third AND circuit), and the multiplexer 43 outputs the delay element D10,
, Dn0, and the selected signal is input to the AND circuit 44. AND
The circuit 44 outputs a logical product signal of the logical sum signal output from the OR circuit 42 and the signal selected by the multiplexer 43 to the AND circuit 32.

Next, the operation of the master exposure apparatus 1 having the above configuration will be described focusing on the operation of the control circuit 22.

In this embodiment, a signal subjected to frequency modulation by switches SW1, SW2,..., SWn and the multiplexer 33 in the second embodiment is further subjected to pulse width correction.

That is, the frequency-modulated digital signal output from the multiplexer 33 is applied to the delay element D00,
The OR circuit 42 outputs a pulse sum expanded by a desired amount as a logical sum signal. And this OR signal is
Each of the delay elements D10, D20,..., Dn0 is delayed by a desired amount, and any of the delayed signals is selected by the multiplexer 33 based on the detection signal of the pulse width detector 38. The OR signal output by the OR circuit 42 and the selected signal and the delay elements D10, D20,
, And an AND signal with a signal not passing through Dn0 is output from the AND circuit 44. As a result, the AND signal is output as a signal obtained by further correcting the pulse width of the frequency-modulated digital signal output from the multiplexer 33 in accordance with the result of the pulse width detection by the pulse width detector 38. The correction of the pulse width is performed such that the pulse width of the frequency-modulated digital signal output from the multiplexer 33 is enlarged when the pulse width is relatively large, and reduced when the pulse width is relatively small.

Then, each of the delay elements D10, D20,.
By setting the delay amount of the signal by Dn0 as desired, the pulse width of the optical signal for exposing the photoresist master 3 can be corrected as desired, so that the digital signal after frequency modulation can be further corrected. . Since this correction can be performed more flexibly than before, information pits having an optimum shape can be formed on the photoresist master 3.

Also, as in the first and second embodiments, since the light intensity of the optical signal for exposing the photoresist master 3 can be adjusted, information pits can be formed with high precision.

[0087]

According to the first aspect of the present invention, there is provided a light source for emitting a laser beam for exposing a photoresist master of an optical disk, and a digital signal obtained by pulse width modulation of a signal of desired information to be recorded on the photoresist master. And a pulse width correction circuit for correcting the digital signal after the pulse width modulation to a desired pulse width different according to the magnitude of the pulse width, based on the pulse width of the digital signal after the correction. By turning on / off the irradiation of the laser beam on the photoresist master, an optical modulator that converts the laser beam into an optical signal whose pulse width is adjusted, and moving the irradiation position of the laser beam on the photoresist master And a pulse width changing device for recording desired information signals to be recorded on the photoresist master. After conversion into a digital signal by, it is possible to correct the different desired pulse width in accordance with the digital signal after the pulse width modulation on the pulse width,
The digital signal after the pulse width modulation can be corrected more flexibly than before so that an information pit having an optimal shape can be formed on the master optical disc.

According to a second aspect of the present invention, in the first aspect of the present invention, the light quantity correction circuit for correcting the pulse width modulated digital signal output from the signal modulator to a different pulse amplitude according to the pulse width. And turning on and off the irradiation of the laser beam onto the photoresist master based on the pulse amplitude of the digital signal after the correction by an optical modulator.
By performing FF, the laser light is converted into an optical signal whose light intensity is adjusted, so that the digital signal after pulse width modulation has a different pulse amplitude according to its pulse width. By performing the correction, the light intensity of the laser beam for exposing the photoresist master can be adjusted, so that the information pits can be formed with high precision.

According to a third aspect of the present invention, in the first or second aspect, the pulse width of the digital signal after the pulse width modulation output from the signal modulator is relatively small by the pulse width correction circuit. When the pulse width of the digital signal is relatively enlarged, and when the pulse width is relatively large, the pulse width of the digital signal is relatively reduced, the pulse width is corrected. Because
When the pulse width of the digital signal after pulse width modulation is relatively small, the pulse width of the digital signal is relatively enlarged,
When the pulse width is relatively large, the pulse width can be corrected so that the pulse width of the digital signal is relatively reduced, so that an information pit having an optimal shape can be formed on the master optical disc.

According to a fourth aspect of the present invention, in the second or third aspect, the pulse width of the pulse width modulated digital signal output from the signal modulator is relatively small by the light amount correction circuit. In this case, the pulse amplitude is corrected so that the pulse amplitude is relatively increased when the pulse amplitude is relatively large and the pulse amplitude is relatively reduced when the pulse amplitude is relatively large. When the pulse width of the subsequent digital signal is relatively small, the pulse amplitude is relatively enlarged, and when the pulse width is relatively large, the pulse amplitude is relatively reduced. Pits can be formed with high precision.

The invention according to claim 5 is the invention according to claims 1, 2,
In the invention described in any one of 3 and 4, the light quantity correction circuit is a signal selection circuit that selects one from a plurality of types of analog signals according to the pulse width of the pulse width modulated digital signal output from the signal modulator. And a first switch for switching the selected analog signal with a logical product signal from a first AND circuit, and an amplifier for amplifying an output signal of the first switch. Therefore, the signal selection circuit and the first switch correct the digital signal after the pulse width modulation to have a different pulse amplitude according to the pulse width, so that the light of the laser beam for exposing the photoresist master is exposed. Since the intensity can be adjusted, an information pit having an optimal shape can be formed on the master optical disc.

According to the technique disclosed in Japanese Patent Application Laid-Open No. 5-122027, every time the pulse width nT of a digital signal after pulse width modulation increases by 1T, a delay line, a timing circuit (such as a shift register) and an AND circuit are added. Although each of them must be increased by one, the present invention can cope with this by simply increasing the second delay circuit one by one, so that a circuit for correcting the modulation signal by the signal modulator can be simplified.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the light amount correction circuit includes a plurality of types of analog signal according to the pulse width of the pulse width modulated digital signal output from the signal modulator. , A first switch for switching the selected analog signal with a logical product signal from the first AND circuit, and amplifying the output signal of the first switch. The first signal selection circuit and the first switch allow the digital signal after pulse width modulation to have different pulse amplitudes according to the pulse width. By correcting, the light intensity of the laser beam that exposes the photoresist master can be adjusted,
Information pits can be formed with high precision.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, there is provided a differentiating circuit for converting a switch output signal into a differential waveform and outputting the signal to an amplifier. By making the output signal of the switch a differential waveform and outputting it to the amplifier, the intensity of the optical signal can be made stronger at the front end and weaker at the rear end, so that an information pit having an optimal shape can be formed on the master optical disc. .

According to an eighth aspect of the present invention, in the first or second aspect of the present invention, the pulse width correction circuit frequency-modulates the pulse width modulated digital signal output from the signal modulator to obtain the pulse width. It is characterized by having a frequency modulation circuit that corrects to a desired pulse width different according to the pulse width of the digital signal after width modulation, so that the digital signal after pulse width modulation is frequency-modulated, Since it is possible to correct the pulse width of the digital signal to a different desired pulse width, it is possible to form an information pit having an optimal shape on the master optical disc.

According to a ninth aspect of the present invention, in the eighth aspect of the present invention, the frequency modulation circuit is configured to control the relative width when the pulse width of the pulse width modulated digital signal output from the signal modulator is relatively large. The frequency modulation is performed so that the frequency becomes high in frequency, and the frequency modulation is stopped when the signal is relatively small. When the pulse width is relatively large, the frequency modulation is performed so as to have a relatively high frequency, and when the pulse width is relatively small, the frequency modulation is stopped, so that the pulse width of the digital signal after the pulse width modulation is relatively large. The pulse width can be corrected so that the pulse width of the digital signal is relatively widened when the pulse width is small, and relatively reduced when the pulse width is relatively large. Therefore, it is possible to form the information pits of optimum shape optical disc master.

According to a tenth aspect of the present invention, in the invention according to the eighth or ninth aspect, when the pulse amplitude of the pulse width modulated digital signal output from the signal modulator is relatively small, the light amount correction circuit is used. Is characterized in that the pulse amplitude is corrected so that the pulse amplitude is relatively enlarged, and when the pulse amplitude is relatively large, the pulse amplitude is relatively reduced. The pulse amplitude can be corrected so that when the pulse width of the digital signal is relatively small, the pulse amplitude is relatively enlarged, and when the pulse width is relatively large, the pulse amplitude is relatively reduced. Information pits can be formed with high accuracy.

The eleventh aspect of the present invention relates to the eighth aspect,
In the invention described in any one of 9, 9 and 10, the frequency modulation circuit includes a plurality of second switches for selecting and non-selecting a clock signal for controlling the signal modulator by turning on and off; A second signal selection circuit for selecting one of the clock signals output from the plurality of second switches in accordance with a pulse width of the digital signal after pulse width modulation to be output; And a second AND circuit for outputting a logical product signal of the digital signal output from the width modulation circuit.
F, selecting or deselecting a clock signal for controlling the signal modulator, and outputting a clock signal output from a plurality of second switches according to the pulse width of the digital signal output from the signal modulator after pulse width modulation. By selecting one of them and outputting a logical product signal of the selected clock signal and the digital signal output by the pulse width modulation circuit, the digital signal after pulse width modulation is changed according to the magnitude of the pulse width. Since the pulse width can be corrected to a different desired pulse width, the digital signal after the pulse width modulation can be corrected more flexibly than before, and an information pit having an optimal shape can be formed on the optical disk master.

In the technique disclosed in Japanese Patent Application Laid-Open No. 5-122027, every time the pulse width nT of a digital signal after pulse width modulation increases by 1T, a delay line, a timing circuit (such as a shift register) and an AND circuit are added. Although each of them must be increased by one, in the present invention, it is possible to cope only by increasing the second switches one by one, so that the circuit configuration can be simplified.

According to a twelfth aspect of the present invention, in accordance with the eleventh aspect of the present invention, the light quantity correction circuit includes a plurality of types of analog signal according to the pulse width of the pulse width modulated digital signal output from the signal modulator. A signal selecting circuit for selecting one of the following, a third switch for switching the selected analog signal with a logical product signal output from the second AND circuit, and amplifying an output signal of the third switch. And a third switch for correcting the digital signal after the pulse width modulation to have a different pulse amplitude according to the pulse width by the signal selection circuit and the third switch. Thus, the light intensity of the laser beam for exposing the photoresist master can be adjusted, so that information pits can be formed with high accuracy.

According to a thirteenth aspect, in the twelfth aspect, the clock signal selected by the signal selection circuit in accordance with the pulse width of the pulse width modulated digital signal output from the signal modulator. And a pulse width control circuit for correcting the pulse width of the clock signal selected by the signal selection circuit after the pulse width modulation output from the signal modulator. The digital signal after pulse width modulation can be corrected more flexibly than before so that information pits of the optimal shape can be formed on the master optical disc. it can.

According to a fourteenth aspect of the present invention, in the thirteenth aspect, the pulse width control circuit comprises a third delay circuit for delaying the clock signal selected by the signal selection circuit by a fixed amount; A plurality of second OR circuits for outputting a logical sum signal of a signal and a digital signal obtained by delaying the clock signal by the third delay circuit; and a plurality of second OR circuits provided for each type of the clock signal. A fourth delay circuit that delays according to the pulse width of the pulse width modulated digital signal output from the modulator; the OR signal; and a digital signal obtained by delaying the OR signal by the fourth delay circuit. And a third AND circuit that outputs a logical product signal of the signal modulators. Therefore, by adjusting the amount of delay by each fourth delay circuit as desired, the signal modulator The digital signal after frequency modulation can be further corrected according to the pulse width of the digital signal after pulse width modulation to be applied, and the digital signal after pulse width modulation can be corrected more flexibly than before, and An information pit having an optimal shape can be formed on the master.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of a master exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a control circuit of the master exposure apparatus.

FIG. 3 is a block diagram of a control circuit showing a second embodiment of the present invention.

FIG. 4 is a block diagram of a control circuit showing a third embodiment of the present invention.

FIG. 5 is a block diagram of a pulse width control circuit of the control circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exposure apparatus of an optical disk master 2 Position moving device 4 Position moving device 5 Position moving device 6 Position moving device 11 Light source 12 Laser beam 14 Optical modulator 21 Signal modulator 31 First OR circuit 32 First and second AND circuit 33 frequency modulation circuit, second signal selection circuit 34 first and third signal selection circuits 35 first, second, and third switches 42 second OR circuit 44 third AND circuit D0 first delay circuit , Dn Second delay circuit D00 Third delay circuit D10, D20, ..., Dn0 Fourth delay circuit

Claims (14)

[Claims] A light source that emits a laser beam for exposing a photoresist master of an optical disc; a signal modulator that converts a signal of desired information to be recorded on the photoresist master into a digital signal by pulse width modulation; A pulse width correction circuit that corrects the digital signal after pulse width modulation to a desired pulse width that differs according to the magnitude of the pulse width; and a pulse width correction circuit that corrects the laser light to the photoresist master based on the pulse width of the corrected digital signal Irradiation ON, O
An optical modulator that converts the laser light into an optical signal whose pulse width is adjusted by performing FF, and a position moving device that moves an irradiation position of the laser light on the photoresist master. Exposure device for optical disc master. 2. A light quantity correction circuit for correcting a pulse width modulated digital signal output from a signal modulator to a different pulse amplitude in accordance with the pulse width, wherein the light modulator corrects the pulse of the corrected digital signal. 2. The optical disc master according to claim 1, wherein the laser light is turned on and off on the photoresist master based on the amplitude to convert the laser light into an optical signal whose light intensity is adjusted. Exposure equipment. 3. When the pulse width of the digital signal output from the signal modulator after the pulse width modulation is relatively small, the pulse width of the digital signal is relatively widened and relatively large. 3. The apparatus according to claim 1, wherein the pulse width is corrected so that the pulse width of the digital signal is relatively reduced. 4. A light amount correction circuit, when a pulse width of a digital signal after pulse width modulation output from a signal modulator is relatively small, a pulse amplitude is relatively enlarged, and when a pulse width is relatively large, a pulse is enlarged. 4. The apparatus according to claim 2, wherein the pulse amplitude is corrected so that the amplitude is relatively reduced. 5. A pulse width correction circuit, comprising: a first delay circuit for delaying a pulse width modulated digital signal output from a signal modulator by a fixed amount; a pulse delay modulation digital signal and the digital signal. A first OR circuit for outputting a logical sum signal of the digital signal delayed by the first delay circuit; and a plurality of OR circuits each for a different pulse width of the digital signal after the pulse width modulation, and A second delay circuit that delays according to the magnitude of the pulse width; and a first that outputs a logical product signal of the logical sum signal and a digital signal obtained by delaying the logical sum signal by the second delay circuit The exposure apparatus for an optical disc master according to any one of claims 1, 2, 3, and 4, further comprising an AND circuit. 6. A light amount correction circuit comprising: a first signal selection circuit for selecting one of a plurality of types of analog signals according to a pulse width of a digital signal after pulse width modulation output from a signal modulator; 6. The apparatus according to claim 5, further comprising: a first switch for switching the analog signal obtained by a logical product signal from a first AND circuit; and an amplifier for amplifying an output signal of the first switch. Exposure equipment for optical disc masters. 7. The exposure apparatus according to claim 6, further comprising a differentiating circuit for converting the output signal of the first switch into a differential waveform and outputting the signal to an amplifier. 8. A pulse width correction circuit frequency-modulates the pulse width modulated digital signal output from the signal modulator to a desired pulse width different according to the pulse width of the pulse width modulated digital signal. 3. The apparatus according to claim 1, further comprising a frequency modulation circuit for performing correction. 9. The frequency modulation circuit, when the pulse width of the digital signal output from the signal modulator after the pulse width modulation is relatively large, performs frequency modulation so as to have a relatively high frequency, and is relatively small. 9. The method according to claim 8, wherein the frequency modulation is stopped at the time.
Exposure apparatus for an optical disc master according to claim 1. 10. A light amount correction circuit, wherein the pulse amplitude of a digital signal output from a signal modulator after pulse width modulation is relatively small, the pulse amplitude is relatively enlarged, and if it is relatively large, the pulse amplitude is relatively large. 10. The apparatus according to claim 8, wherein the pulse amplitude is corrected so as to relatively reduce. 11. A frequency modulation circuit comprising: a plurality of second switches for selecting and deselecting a clock signal for controlling a signal modulator by turning on and off; and a plurality of second switches after pulse width modulation output from the signal modulator. A second signal selection circuit for selecting one of the clock signals output from the plurality of second switches according to a pulse width of the digital signal; and a digital signal output from the selected clock signal and a pulse width modulation circuit. A second AND that outputs a logical product signal with the signal
And a circuit.
0. An exposure apparatus for an optical disc master according to any one of the above items. And a third signal selection circuit for selecting one of a plurality of types of analog signals in accordance with the pulse width of the digital signal output from the signal modulator after pulse width modulation. A third switch for switching the selected analog signal with a logical product signal output by a second AND circuit; and an amplifier for amplifying an output signal of the third switch. Item 12. An exposure apparatus for an optical disk master according to item 11. 13. A pulse width control circuit for desirably correcting a pulse width of a clock signal selected by a signal selection circuit according to a pulse width of a digital signal output from a signal modulator after pulse width modulation. 13. The method according to claim 12, wherein
Exposure apparatus for an optical disc master according to claim 1. 14. A pulse width control circuit, comprising: a third delay circuit for delaying the clock signal selected by the signal selection circuit by a fixed amount; and the clock signal and the clock signal are delayed by the third delay circuit. A second OR circuit that outputs a logical sum signal with a digital signal; and a fourth OR circuit that is provided for each type of the clock signal and delays the logical sum signal according to the pulse width of the digital signal after pulse width modulation. And a third AND circuit that outputs a logical product signal of the logical sum signal and a digital signal obtained by delaying the logical sum signal by the fourth delay circuit. An exposure apparatus for an optical disk master according to claim 13.