JP2002203341A - Optical recording medium, apparatus and method for manufacturing optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium which can always and stably keep the operation of a servo circuit in a recording and reproducing device. SOLUTION: In the optical recording medium 10 provided with groove tracks 11 which consist of a 1st area Ba, where recording information are recorded, and a 2nd area Ca, where prescribed data are formed as embossed pit train 19 to obstruct the read of other data to be overwritten and recorded and land tracks 12 are formed between adjacent groove tracks 11, the depth Ed and duty of the embossed pit train 19 are set so that the radial push pull signal level of the 2nd area is almost >=80% of a radial push pull signal level in the 1st area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical recording medium capable of optically recording recorded information, an optical recording medium manufacturing apparatus for forming such an optical recording medium, and a method for manufacturing an optical recording medium.

[0002]

2. Description of the Related Art At present, a read-only DVD-Video disc in which contents are recorded in advance and a DVD-RW (DV-DV) as an optical recording medium capable of optically recording recorded information.
D Re-recordable) discs are known. FIG.
Shows an enlarged view of a main part of the DVD-RW disc. Specifically, a buffer zone (area in the direction of arrow Ba in the figure) in the lead-in area and a control data zone (arrow Ca in the figure) arranged immediately before the buffer zone are shown. 2 shows an enlarged view of a boundary portion with a region in the direction of FIG. In this figure, the upper and lower surfaces of the disk are drawn inverted for easy understanding of the disk structure.

As shown in FIG. 1, according to a DVD-RW disc, its buffer zone, data area, etc.
In the first area where recording information is recorded, a groove track 1 having a depth of Gd [nm] for recording the recording information.
Are formed in a meandering manner, and land pre-pits 3 for generating various information such as addresses are formed on land tracks 2 located between adjacent groove tracks 1. Further, according to the DVD-RW disc, DVD-Video by bit by bit is used.
o To prevent illegal copying of the disc, control information to be recorded therein is recorded in the control data zone as an embossed pit row 4 having the same depth Gd [nm] as the groove track. The groove track has just been interrupted.

[0004]

As described above, DVDs
According to the RW disc, since the emboss pit rows 4 are embedded in the control data zone, even if the DVD-Video disc is illegally copied by bit-by-bit, the control data zone is overwritten. The reading of the read data is hindered by the reproduction output by the embossed pit row 4, and illegal copying is made invalid. However, in the DVD-RW disk thus configured, since the embossed pit row 4 is formed, the radial push-pull signal level in the control data zone (second area) indicates that the recording information is recorded. The radial push-pull signal level in the first area decreases, causing a problem that the operation of the tracking servo circuit and the spindle servo circuit in the recording / reproducing apparatus becomes unstable.

The present invention has been made in view of the above problems, and has as its object to obtain a constant radial push-pull signal over the entire area of a disk and to stably operate a servo circuit in a recording / reproducing apparatus. An object of the present invention is to provide an optical recording medium that can be kept, an optical recording medium manufacturing apparatus for forming the optical recording medium, and an optical recording medium manufacturing method.

[0006]

According to a first aspect of the present invention, there is provided an optical recording medium capable of optically recording recorded information. A groove track including a first area to be recorded, and a second area in which predetermined data is formed as an emboss pit row and prevents reading of other data overwritten on the emboss pit row. And a land track formed between the adjacent groove tracks, wherein the embossed pit row has a radial push-pull signal level in the second area substantially equal to a radial push-pull signal level in the first area. It is characterized by being formed to be 80% or more.

According to a second aspect of the present invention, there is provided an optical recording medium according to the first aspect, wherein the embossed pit row has an average duty (Duty [Duty [ %]), The depth of the embossed pit row (Ed [nm]), the wavelength of the light beam (λ
[Nm]), the substrate refractive index (n
[Nm]) and the depth of the groove (Gd [nm]), the following formula 4 is substantially satisfied.

[Formula 4] Duty = 0.04 (Ed−λ / 8n) ² + (−
0.07Gd ² + 6Gd-35.6)

An optical recording medium manufacturing apparatus according to a third aspect of the present invention is an optical recording medium manufacturing apparatus for manufacturing an optical recording medium capable of optically recording recorded information using a master optical disc. A first area for recording the recording information on the optical disc master, and a second area in which predetermined data is formed as an embossed pit row and prevents reading of other data overwritten on the embossed pit row. And a groove track forming means for forming a groove track composed of: a groove track forming means, wherein the groove track forming means has a radial push-pull signal level in the second area substantially equal to a radial push-pull signal level in the first area. The embossed pit row is formed so as to be 80% or more.

An optical recording medium manufacturing apparatus according to a fourth aspect of the present invention is the optical recording medium manufacturing apparatus according to the third aspect, wherein the average duty (Duty [%]) of the embossed pit row is: The depth of the embossed pit row (E
d [nm]), the wavelength of the light beam (λ [nm]),
When the substrate refractive index (n [nm]) of the optical recording medium and the depth of the groove (Gd [nm]), the embossed pit row is formed so as to substantially satisfy the following Expression 5. Features.

[Formula 5] Duty = 0.04 (Ed−λ / 8n) ² + (−
0.07Gd ² + 6Gd-35.6)

According to a fifth aspect of the present invention, there is provided an optical recording medium manufacturing method for manufacturing an optical recording medium capable of optically recording recorded information using an optical disk master. A first area for recording the recording information on the optical disc master, and a second area in which predetermined data is formed as an embossed pit row and prevents reading of other data overwritten on the embossed pit row. And a groove track forming step of forming a groove track composed of: a radial track having a radial push-pull signal level in the second area which is substantially equal to a radial push-pull signal level in the first area. The embossed pit row is formed so as to be 80% or more.

According to a sixth aspect of the present invention, there is provided the optical recording medium manufacturing method according to the fifth aspect, wherein an average duty (Duty [%]) of the embossed pit row is provided. The depth of the embossed pit row (E
d [nm]), the wavelength of the light beam (λ [nm]),
When the substrate refractive index (n [nm]) of the optical recording medium and the depth of the groove (Gd [nm]), the embossed pit row is formed so as to substantially satisfy the following Expression 6. Features.

[Formula 6] Duty = 0.04 (Ed−λ / 8n) ² + (−
0.07Gd ² + 6Gd-35.6)

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Incidentally, DVD-R which is one of optical recording media capable of optically recording recording information is used.
An embodiment in which the present invention is applied to a W disk (hereinafter abbreviated as DVD-RW) will be described.

First, the recording format of a DVD-RW will be described with reference to FIGS. In addition, FIG.
FIG. 3 is a diagram illustrating a physical recording area on a DVD-RW after video information has been recorded in accordance with the VD-RW format.

As shown in FIG. 1, in the information area of the DVD-RW, the start point of the information area (the start point of the physical sector)
, A lead-in area, a data area, and a lead-out area are sequentially recorded radially outward. The lead-in area is an area that is first accessed during recording and reproduction of the DVD-RW, and includes a disc size, a minimum read rate, a disc structure, and the like.
-Physical information on the RW is recorded. The data area is an area in which content, that is, recording information is mainly recorded. For example, as content to be recorded,
There are image data, audio data, computer-readable data or programs, and the like. The lead-out area is an area subsequent to the data area, and data [00h] indicating the end of recording is recorded for a predetermined period.

FIG. 2 is a diagram showing a structure in the lead-in area. In the lead-in area, an initial zone in which data [00h] is recorded, a reference code zone in which data for generating a specific channel bit pattern (3T-6T-7T) is recorded, and data [00h] are recorded. It is composed of a buffer zone 1, a control data zone in which various control information is recorded, and a buffer zone 2 for leading to a data area in which data [00h] is recorded.

The control data zone is located at the same address as the control data zone on the DVD-Video disc as described above, and the control information recorded in advance in this zone is embedded as a series of embossed pits. . Therefore, in this zone, even if other data is overwritten and recorded, reading of the data is hindered by reproduction output by the embossed pit train.

Next, a recording format of pre-information pre-recorded on the DVD-RW will be described with reference to FIG. In FIG. 3, the upper part shows the recording format of the recording information, and the lower part shows the wobbling waveform indicating the wobbling state (the plan view of the groove track) of the groove track 11 for recording the recording information. In FIG. 3, an upward arrow between the recording information and the wobbling waveform schematically indicates a position where a prepit is formed. The wobbling waveform shown in FIG. 3 is shown with an amplitude larger than the actual amplitude for easy understanding.

The recording information recorded on the DVD-RW is divided in advance into sync frames as information units as shown in FIG. One sync frame is 1488 times (1488) a channel bit length (hereinafter, referred to as T) defined by a recording format when recording information is recorded.
T), which is the length of the first three sync frames.
The portion having a length of 2T is used as synchronization information SY for synchronizing each sync frame.

The pre-information recorded on the DVD-RW is recorded for each sync frame. When the pre-information is recorded on the DVD-RW, one pre-pit B2 is always formed on the land track adjacent to the area where the synchronization information SY of the sync frame is recorded as a signal indicating the synchronization signal in the pre-information. Two or one pre-pits (B1, B0) are formed on a land track adjacent to the first half of the sync frame other than the synchronization information SY to indicate the contents of the pre-information to be recorded.

Normally, pre-information is recorded by forming pre-pits in even-numbered sync frames (hereinafter referred to as EVEN frames). That is, in FIG. 3, a pre-pit is formed in the EVEN frame (indicated by a solid line upward arrow in FIG. 3), and an ODD adjacent to the pre-pit is formed.
No prepits are formed in the frame. More specifically,
When a pre-pit is formed in an EVEN frame, all pre-pits (pre-pits B2, B1 and B0) are formed in a sync frame at the head of a recording sector, and in a sync frame other than the head of a recording sector, recording is performed in the sync frame. When the pre-information to be recorded is "1", the pre-pits B2 and B0 are formed. When the information to be recorded is "0", the pre-pits B2 and B0 are formed.
Only are formed.

On the other hand, odd-numbered sync frames (hereinafter, referred to as odd-numbered sync frames)
When forming pre-pits in an ODD frame)
In the sync frame at the head of the recording sector, prepits B2 and B1 are formed.
It is formed in the same manner as in the case of the VEN frame.

Whether the pre-pit is formed in the sync frame of the EVEN frame or the ODD frame is determined depending on the position of the pre-pit previously formed on the adjacent land track. That is, the pre-pit is usually formed in the EVEN frame. However, when the pre-pit is formed in the EVEN frame, the pre-pit is formed in the ODD frame when the pre-pit on the adjacent land track formed in the disk radial direction is approached. Is formed. By forming the pre-pits in this manner, the pre-pits do not exist at the adjacent land track positions, so that it is possible to avoid the influence of crosstalk in detecting the pre-pits.

On the other hand, the groove track is wobbled at a constant wobbling frequency f0 of 140 kHz (frequency at which eight wobble signals are included in one sync frame) over all the sync frames. The recording / reproducing apparatus detects the signal for controlling the rotation of the spindle motor by extracting the constant wobbling frequency f0, and generates a recording clock signal.

Next, a DVD-R according to an embodiment of the present invention
The structure of the recording surface of W10 will be described with reference to FIG.
This figure shows the boundary between the buffer zone (Ba) in the lead-in area and the control data zone (Ca) located immediately before this buffer zone, as in FIG. 13 described above.

The DVD-RW 10 includes a recording layer made of a phase change material (eg, GeSbTe) as a data recording layer and a multi-layer 14 made of a glassy (ZnS-SiO2) protective layer sandwiching the recording layer. It constitutes a variable optical recording medium. A reflective layer 15 for reflecting the light beam (B) at the time of data reproduction is formed below the multi-layer 14, and a transparent substrate (polycarbonate) 17 is further adhered below the reflective layer 15 by an adhesive layer 18. Also, the light beam (B)
A transparent film (polycarbonate) 16 that protects the multi-layer 14 is provided on the light incident surface side.

As shown in FIG.
Shows a conventional DV shown in FIG. 13 in an area (first area) other than control data, such as a buffer zone.
As with the D-RW disc, a groove track 11 having a depth Gd of approximately 30 [nm] as an information recording track and a land track 12 between adjacent groove tracks 11 are provided.
Are formed, and land prepits 13 having the same depth as the groove track are formed on the land track 12.

The DVD-RW 10 is a conventional DVD.
Similarly to the RW disc, in the control data zone (second area), an emboss pit row 19 having an average Duty = 80%, a land track 11, and a land pre-pit 13 are formed. However, according to the DVD-RW 10 according to the present embodiment, the embossed pit row 19 has the depth Gd of the groove track 11.
It is formed with a depth Ed (50 nm) deeper than (30 nm).

This is the control data zone, ie the radial push-pull signal level in the second area,
This is for matching the level of the radial push-pull signal in the first area for recording other recording information. Hereinafter, various conditions of the emboss pit row 19 for matching the level of the radial push-pull signal will be described. FIG.
This will be described in detail with reference to FIG.

FIG. 5 is a block diagram of a main part of the recording / reproducing apparatus 80. The configuration and operation of the recording / reproducing device 80 will be described with reference to FIG. The recording / reproducing device 80 reflects the laser beam and guides the laser beam to the objective lens 60, and the DVD-RW 10
And a beam splitter 61 that transmits the light beam reflected by the recording information surface of the DVD-RW 10 and guides the light beam to the photodetector 62, and condenses the light beam reflected by the beam splitter 61 so as to be focused on the recording information surface of the DVD-RW 10. Objective lens 60 and D
A radial push-pull type photodetector 62 for detecting the amount of light beam reflected by the recording information surface of the VD-RW 10 with the four light receiving elements A to D, and a light-current conversion output from the photodetector 62 Arithmetic processing unit 76 for arithmetically processing signals
And

The figure inside the circle in FIG.
1 schematically shows how the light detector 62 detects the reflected light of the light beam irradiated on the pre-pit 13 and the pre-pit 13;
The photodetector 62 is arranged on the center line of the groove track 11, and detects the reflected light on the groove track 11 with the four light receiving elements A to D. The recording / reproducing device 80 performs an arithmetic processing on the light-current conversion signals output from the four light receiving elements A to D of the photodetector 62 in the arithmetic processing unit 75, so that a tracking error signal, an RF signal, I try to get a pre-pit signal.

The arithmetic processing unit 76 includes four current / voltage converters 63 to 66, five adders 67 to 70 and 72,
It comprises a subtractor 71, a low-pass filter (LPF) 73, a high-pass filter (HPF) 74, and a comparator 75. Output signals A to D of the photodetector 62
Are supplied to four current / voltage converters 63 to 66, respectively, and are converted from current values to voltage values by the respective current / voltage converters 63 to 66. Output signals from the current / voltage converter 63 and the current / voltage converter 66 are added by an adder 67. The output signals of the current / voltage converter 64 and the current / voltage converter 65 are added by an adder 69. And the adder 6
7 and the output signal of the adder 69 are subtracted by a subtractor 71,
It is output from the subtractor 71 as a radial push-pull signal in the form of (A + D)-(B + C). The radial push-pull signal has a pre-pit signal component removed by the LPF 73 and is output as a tracking error signal. The tracking error signal component is removed from the radial push-pull signal output from the subtracter 71 by the HPF 74, and is compared with a predetermined reference level by the comparator 75, so that the signal is output as a pre-pit detection signal.

On the other hand, the output signals of the current / voltage converter 63 and the current / voltage converter 64 are added by an adder 68. The output signals of the current / voltage converter 65 and the current / voltage converter 66 are added by an adder 70. And the adder 6
8 and the output signal of the adder 70 are added by the adder 72,
It is output as an RF signal from the adder 70 in the form of (A + B) + (C + D).

The recording / reproducing device 80 extracts the wobbling frequency of the groove track 11 when recording information on the DVD-RW
Is controlled at a predetermined rotation speed, and the pre-pit 1
3, the pre-information is acquired in advance, and the optimum output of the light beam as the recording light is set based on the pre-information. Further, the recording / reproducing device 80 obtains address information or the like indicating a position on the DVD-RW 10 where the recording information is to be recorded by detecting the pre-pit 13, and moves the recording information to a desired position based on the address information. Record.

The recording / reproducing device 80 irradiates a light beam corresponding to the recording information onto the groove track 11 to form information pits on the groove track 11. At this time, the size of the light spot (SP) is set so that the light spot irradiates not only the groove track 11 but also the pre-pit 13 formed on the land track 12 as shown in FIG. . Therefore, the recording / reproducing device 80
Based on the radial push-pull signal generated by detecting the reflected light of the light spot (SP), the pre-pit 13 can be detected to acquire the pre-information.

FIG. 6 is a graph showing the relationship between the radial push-pull signal level and the groove depth Gd and emboss depth Ed formed on the DVD-RW 10 by simulation. The horizontal axis represents the groove depth Gd.
And the emboss depth Ed, and the vertical axis shows the radial push-pull signal. The curve shown by the dotted line in the figure shows the relationship between the depth Gd of the groove track 11 and the radial push-pull signal level Vg, and the curve shown by the solid line shows the average D
The relation of the radial push-pull signal level Ve with respect to the depth Ed of the emboss pit row 19 having the duty ratio of 80% is shown. The curve indicated by the dashed line is the average Duty.
The relationship between the radial push-pull signal level and the depth Ed of the embossed pit row 19 having a ratio of 50% is shown.

As described above, the DVD shown in FIG.
According to -RW, since the depth Gd of the groove track 1 and the depth Ed of the emboss pit row 4 are both formed to be approximately 30 nm, the radial push-pull signal level in the groove track 1 as shown in FIG. Vg is approximately 0.42, and the radial push-pull signal level in the emboss pit row 4 is approximately 0.32. That is,
The radial push-pull signal level Ve in the embossed pit row 4 is reduced to about 76% of the radial push-pull signal level in the groove track 1. Further, when the depth Gd of the groove track 1 and the depth Ed of the emboss pit row 4 are both formed to be approximately 30 nm, and the average duty ratio of the emboss pit row is 50%, the radial push-pull in the groove track 1 The signal level Vg is approximately 0.42, but the radial push-pull signal level Ve in the embossed pit row 4 is approximately 0.22.
Becomes That is, the radial push-pull signal level Ve in the embossed pit row 4 is about 48 times the radial push-pull signal level in the groove track 1.
%.

On the other hand, according to the DVD-RW 10 of this embodiment, the depth Gd of the groove track 11 is formed to be approximately 30 nm, and the depth Ed of the embossed pit row 19 is formed to be approximately 50 nm. Accordingly, as shown in FIG. 6, the radial push-pull signal level in the embossed pit row 19 rises to approximately 0.42, which is substantially the same as the radial push-pull signal level in the groove track 11.

As described above, the groove track 1
1 is formed with a depth Gd = about 30 nm, the average Dut
Depth Ed = approximately 50n in embossed pit row 19 of y = 80%
If it is formed with m, the radial push-pull signal level Vg in the groove track and the radial push-pull signal level Ve in the embossed pit row can be made substantially the same. However, the present invention is not limited to the numerical values of the depth Gd of the groove track and the average Duty and the depth Ed of the embossed pit row. Less than,
In order to make the radial push-pull signal level Ve in the emboss pit row approximately 80% or more of the radial push-pull signal level Vg in the groove track, the depth Gd of the groove track and the average Du of the emboss pit row.
The relationship between ty and depth Ed will be described with reference to FIGS.

FIGS. 7 to 9 show the depth G of the groove track.
When d is fixed to a predetermined depth, the depth Ed of the emboss pit row and the average Dut thereof for obtaining the same radial push-pull signal level in the emboss pit row as the radial push-pull signal level in the groove track.
The relationship with the y ratio is obtained by simulation, and this is graphed. The horizontal axis indicates the depth Ed [nm] of the emboss pit row, and the vertical axis indicates the average D of the emboss pit row.
uty ratio [%] is shown.

FIG. 7 shows that the depth Gd of the groove track is 1
This is an example when 0 nm is set. In FIG. 7, for example, when the depth Ed of the embossed pit row is 15 nm and the average duty ratio of the embossed pit row is 76%, the radial push-pull signal on the groove track and the radial push-up signal on the embossed pit row The level of the pull signal becomes the same. When the depth Ed of the embossed pit row is 30 nm and the average duty ratio is 36%, the levels of both radial push-pull signals become the same. FIG. 7 is a graph obtained in this manner, and when the depth Ed of the embossed pit row is approximately 50 nm (accurately, 51.4 nm), a quadratic curve with the minimum average duty ratio is obtained. The quadratic curve obtained here can be approximated by Expression 7 below.

[Formula 7] Duty = 0.0461 Ed ² −4.720 Ed + 136.1
Three

FIG. 8 shows that the depth Gd of the groove track is 2
This is an example when 0 nm is set. FIG. 8 is a diagram in which the result of a simulation performed in the same procedure as that described with reference to FIG. 7 is plotted. The graph of FIG. 8 shows that the average duty ratio of the embossed pit row becomes larger as a whole as compared with the example shown in FIG. 7, and the average duty ratio of the embossed pit row is set when the depth Ed of the embossed pit row is approximately 50 nm. A minimized quadratic curve is obtained. The quadratic curve obtained here can be approximated by Expression 8 below.

[Formula 8] Duty = 0.0401 Ed ² −4.149 Ed + 164.9

Similarly, FIG. 9 shows an example in which the depth Gd of the groove track is set to 30 nm. Compared with the example shown in FIG. 8, the average duty ratio of the embossed pit row is further increased, and when the depth Ed of the embossed pit row is approximately 50 nm, a quadratic curve in which the average duty ratio of the embossed pit row is minimized is obtained. can get. The quadratic curve obtained here can be approximated by Expression 9 below.

[Formula 9] Duty = 0.0423 Ed ² −4.353 Ed + 192.7

FIG. 10 is a plot of the minimum value f (Gd) of the average duty ratio of the embossed pit rows shown in FIGS. 7 to 9, and the horizontal axis represents the depth Gd of the groove track.
And the vertical axis shows the minimum value f (Gd). The quadratic curve obtained here can be approximated by Expression 10 below.

[Equation 10] f (Gd) = − 0.07 Gd ² +6 Gd−35.6

When the depth Gd of the groove track and the depth Ed of the emboss pit row are selected based on the above-mentioned equations 7 to 10, the average duty of the emboss pit row can be approximated by the following equation 11.

[Formula 11] Duty = 0.04 (Ed−λ / 8n) ² + f
(Gd) where λ is the wavelength [nm] of the light beam, and n is the DVD-R
The refractive index of the substrate of W10, f (Gd), is a minimum value at which the average duty ratio of the embossed pit row is minimized.
The wavelength (λ) of the light beam is 650 nm, and the refractive index (n) of the substrate
Is 1.58, the value of λ / 8n is approximately 51.4 nm, and the minimum value f (Gd) is a unique value determined by the depth Gd of the groove track.

For example, the groove track depth Gd = 3
0 nm, emboss pit row depth Ed = 50 nm, λ / 8n
= 51.4 nm, f (Gd) = 8 from Expression 10.
1.4 nm was obtained, and the average Duty = 81.
4784 is obtained. As described with reference to FIG. 6, when the depth Gd of the groove track is 30 nm and the embossed pit row having an average duty ratio of about 80% is formed at a depth of 50 nm as described with reference to FIG. This coincides with the result that the levels of the radial push-pull signal and the radial push-pull signal on the embossed pit row become substantially the same.

As described above, the DVD-RW 10 of this embodiment
According to the above, if a numerical value satisfying Expressions 10 and 11 is set in the relationship between the depth Gd of the groove track, the depth Ed of the embossed pit row, and the average duty, the radial push-pull signal level Ve on the embossed pit row 19 is set. Can be reliably increased to about 80% or more of the radial push-pull signal level Vg on the groove track 11.

Next, an optical recording medium manufacturing apparatus 50 for cutting the optical disk master 40 required for manufacturing the DVD-RW 10 of this embodiment will be described with reference to the block diagram shown in FIG. The optical recording medium manufacturing apparatus 50 includes a land data generator 20 and a parallel / serial converter (P /
S) 21, a preformat encoder 22, a clock signal generator 23, a light beam generator 24, an objective lens 25, a spindle motor 26, a rotation detector 27, a rotation servo circuit 28, a feed unit 29,
It comprises a position detector 30, a feed servo circuit 31, a controller 32, a groove data generator 33, a wobbling signal generator 34, and a switch 35.

The master optical disc 40 mounted on the spindle motor 26 is composed of a glass substrate 41 and a resist layer 42 coated on the glass substrate 41. The resist layer 42 is exposed by being irradiated with a light beam B described later, and forms a pit having a shape corresponding to a change in the intensity of the light beam B.

In FIG. 11, the land data generator 20
Is the land track 12 under the control of the controller 32.
The parallel data corresponding to the pre-pit 13 formed above is output. The output parallel data is converted by the parallel / serial converter 21 into serial data. Then, the serial data is input to the pre-format encoder 22 and the clock signal generator 2
On the basis of the clock signal supplied from 3, a pre-pit formation signal SL for actually forming the pre-pit 13 on the master optical disc 40 is output to the light beam generator 24.

On the other hand, the groove data generator 33 generates a groove forming signal SG including recording data formed as the groove track 11 and the embossed pit row 19 under the control of the controller 32, and as a control signal for the switch 35. Output. That is, the switch 35 is turned on / off by the output signal of the groove data generator 33.

The wobbling signal generator 34 generates a wobbling signal for giving a slight undulation to the groove track 11, and outputs it to the switch 35. Switch 3
Reference numeral 5 denotes switching control performed based on the groove data output from the groove data generator 33, and when the terminal is switched to the terminal a, the wobbling signal output from the wobbling signal generator 34 is transmitted to the light beam generator 24.
When the terminal is switched to the terminal b side, the output to the light beam generator 24 is set to the ground level.

The light beam generator 24 generates two light beams A (shown by dotted lines in the figure) and B (shown by solid lines in the figure) for forming the groove track 11 and the prepit 13 on the optical disk master 40, respectively. Emit. The light beam generator 24 emits a light beam A for forming the groove track 11 based on the output of the switch 35 described above. When the switch 35 is switched to the terminal a, a wobbling signal generator is provided. The first light beam A responds to the level change of the wobbling signal output from the first light beam A.
Is displaced in the radial direction of the disk, and the meandering groove track portion on the resist layer 42 is exposed. When the switch 35 is switched to the terminal b and the signal from the switch 35 becomes the ground level, the light beam generator 24 stops emitting the light beam A and stops exposing the resist layer 42. Therefore, by switching the switch 35,
The embossed pit portion can be exposed on the resist layer. Further, the light beam generator 24 includes a controller 32
Based on the control signal PC, the laser power is controlled, and when exposing the embossed pit portion, the laser power of the light beam A is increased to expose the resist layer 42 deeper than the groove track portion.

Further, the light beam generator 24 turns on / off the second light beam B based on the pre-pit forming signal SL output from the pre-format encoder 22, and forms a pre-pit portion between adjacent groove track portions. Expose.

On the other hand, the spindle motor 26 rotates the optical disk master 40, and the rotation detector 27 detects the rotation of the optical disk master 40. Thus, the rotation servo circuit 28 controls the rotation of the optical disk master 40 and outputs a rotation pulse synchronized with the rotation. The position detector 30 detects the position of the feed unit 29 and sends a detection signal to the feed servo circuit 31. Feed servo circuit 3
1 acquires the position information of the feed unit 29 based on the detection signal from the position detector 30, and thereby servo-controls the movement of the feed unit 29.

Next, the cutting process of the master optical disc 40 performed in the optical recording medium manufacturing apparatus 50 according to the present embodiment will be described with reference to the flowchart shown in FIG. This processing is mainly performed by the controller 32 according to a control program recorded in a memory (not shown). In addition, the control program stores the groove tracks 11 on the optical disc master 40.
The groove track portion corresponding to the embossed pit row 19 has a depth of 30 nm and the embossed pit portion corresponding to the embossed pit row 19 has a depth of 50 nm.
An example in which exposure is performed will be described.

As shown in FIG. 12, when the cutting process in the optical recording medium manufacturing apparatus 50 is started, a switch 3 is used to expose a continuous groove track portion.
5 is switched to the a side, and the land data generator 20 is used to expose a pre-pit portion corresponding to the pre-pit 13.
And so on. The groove depth Gd is 30 nm.
The laser power of the light beam generator 24 is set so as to satisfy (Step S1).

Subsequently, the exposure of the groove track portion and the pre-pit portion to the optical disk master 40 is started (step S2). That is, while controlling the rotation servo circuit 28 and the feed servo circuit 31, the drive of the light beam generator 24 is controlled to start the exposure of the master optical disc 40 with the first light beam A and the second light beam B. Then, referring to the address information to be recorded in the pre-pit section, it is determined whether the first light beam A has reached the control data zone (step S3). Note that this determination may be made by detecting whether or not the address information has become the head address 02F200h of the control data zone as shown in FIG. Then, as a result of the determination in step S3, when the first light beam A reaches the control data zone (step S3: YES), the process proceeds to step S4.

In order to expose the embossed pit portion, the groove data generator 33 is controlled to output control data with an average duty = 80%. In order to set the exposure depth to 50 nm, the laser power of the light beam generator 24 is adjusted. (Step S4), and exposure of the embossed pit portion and the pre-pit portion to the optical disk master 40 is started (step S5). Subsequently, it is determined whether the first light beam A has reached the buffer zone 2 with reference to the address information to be recorded in the pre-pit portion (step S6). Note that this determination may be made by detecting whether or not the address information has become the head address 02FE00h of the buffer zone as shown in FIG. Then, as a result of the determination in step S6,
When the first light beam A reaches the buffer zone (Step S6: YES), the process proceeds to Step S7.

In the buffer zone 2 and thereafter, the continuous crew track portion and pre-pit portion are again set to a depth of 30.
Since the exposure must be performed in nm, the groove data generator 33 is controlled to switch the switch 35 to the terminal a side,
Return the laser power of the light beam generator 24 to the initial value,
The grooved track portion and the pre-pit portion are exposed to the optical disc master 40 (step S7). Then, it is determined whether or not the first light beam A has reached the outermost periphery of the master optical disc 40 with reference to the address information to be recorded in the pre-pit section (step S8). As a result of this determination, the first
When it is detected that the light beam A has reached the outermost periphery (step S8: YES), the process proceeds to step S9, where stop control is performed, and a series of operation programs ends.

By performing the above operation control, the spiral groove track 1 is formed on the optical disk master 40.
1. The groove track portion, the emboss pit portion, and the pre-pit portion corresponding to the emboss pit row 19 and the pre-pit 13 are exposed. Thereafter, the optical disk master 40 is subjected to a development process, and the exposed portions are removed. Then, a stamper is formed based on the developed optical disc master 40, and thereafter, the DVD-RW 10 according to the present embodiment is mass-produced by using the stamper according to a known replication process.

The present invention is not limited to the above embodiment. For example, according to the above-described embodiment, an example in which the present invention is applied to a DVD-RW disc has been described. However, the present invention may be applied to an optical recording medium of another system such as a DVD-R or a DVD-RAM. Of course. Also,
The depth Gd of the groove track 11 is 50 nm, the depth Ed of the embossed pit row 19 is 80 nm, and the average duty is 80%.
However, these values can take various values based on the above Expressions 10 and 11.

[0062]

According to the present invention, a substantially constant radial push-pull signal can be obtained over the entire area of the disk.
The operation of the servo circuit in the recording / reproducing apparatus can be always kept stable.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an information recording surface of a DVD-RW disc.

FIG. 2 is a diagram showing a structure of a lead-in area of a DVD-RW disc.

FIG. 3 is a diagram showing a recording format of pre-information recorded in advance on a DVD-RW disc.

FIG. 4 is a diagram showing a structure of a recording surface of the DVD-RW according to the embodiment.

FIG. 5 is a main block diagram of the recording / reproducing apparatus.

FIG. 6 is a diagram illustrating a relationship between a depth Gd of a groove track and a depth Ed of an emboss pit row, and a radial push-pull signal level.

FIG. 7 shows a depth Ed of an embossed pit row and an average Dut thereof for obtaining the same radial push-pull signal level when the depth Gd of the groove track is 10 nm.
The figure which shows the relationship with a y ratio.

FIG. 8 shows a depth Ed of an embossed pit row and an average Dut thereof for obtaining the same radial push-pull signal level when the depth Gd of the groove track is set to 20 nm.
The figure which shows the relationship with a y ratio.

FIG. 9 shows a depth Ed of an embossed pit row and an average Dut thereof for obtaining the same radial push-pull signal level when the depth Gd of the groove track is 30 nm.
The figure which shows the relationship with a y ratio.

FIG. 10 is a diagram illustrating a relationship between a depth Gd of a groove track and each minimum value f (Gd) that minimizes the average duty ratio of the embossed pit rows illustrated in FIGS. 7 to 9;

FIG. 11 is a schematic configuration diagram of an optical recording medium manufacturing apparatus according to the present invention.

FIG. 12 is an operation flowchart of the optical recording medium manufacturing apparatus.

FIG. 13 is a diagram showing a structure of a recording surface of a conventional DVD-RW disc.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... DVD-RW 11 ... Groove track 12 ... Land track 13 ... Pre-pit 14 ... Multi-layer 15 ... Reflective layer 16 ... Transparent film 17 ... Transparent substrate 18 ··· Adhesive layer 19 ··· Emboss pit row 20 ··· Land data generator 21 ··· Parallel / serial converter (P / S) 22 ··· Preformat encoder 23 ··· Clock signal generator 24 ... Light beam generator 25 ... Objective lens 26 ... Spindle motor 27 ... Rotation detector 28 ... Rotary servo circuit 29 ... Feed unit 30 ... Position detector 31 ... Feed servo circuit 32 ・ ・ ・ Controller 33 ・ ・ ・ Groove data generator 34 ・ ・ ・ Wobbling signal generator 35 ・ ・ ・ Switch 40 ・ ・ ・ Optical disc master 1 ... glass substrate 42 ... resist layer 50 ... optical recording medium manufacturing apparatus 76 ... processing unit 80 ... recording and reproducing apparatus

Continuation of the front page F term (reference) 5D029 WB17 WC05 5D090 AA01 CC04 DD01 EE13 FF02 5D121 AA02 DD05

Claims (6)

[Claims] 1. An optical recording medium capable of optically recording recording information, wherein a first area for recording the recording information and predetermined data are formed as a series of emboss pits. A second area for preventing reading of other data to be overwritten on the column, a land track formed between adjacent groove tracks, and the embossed pit row includes: An optical recording medium, wherein the radial push-pull signal level in the second area is formed to be about 80% or more of the radial push-pull signal level in the first area. 2. The emboss pit row includes an average duty (Duty [%]) of the emboss pit row, a depth (Ed [nm]) of the emboss pit row, and a wavelength (λ [nm]) of the light beam. , The substrate refractive index (n [nm]) of the optical recording medium, and the depth of the groove (Gd [n
2. The optical recording medium according to claim 1, wherein the following formula 1 is substantially satisfied when m]). [Formula 1] Duty = 0.04 (Ed−λ / 8n) ² + (− 0.
07Gd ² + 6Gd-35.6) 3. An optical recording medium manufacturing apparatus for manufacturing an optical recording medium capable of optically recording recording information by using an optical disk master, wherein an optical recording medium for recording the recording information on the optical disk master. Groove track forming means for forming a groove track including a first area and a second area in which predetermined data is formed as an embossed pit row and prevents reading of other data overwritten on the embossed pit row. Wherein the groove track forming means forms the embossed pit row so that the radial push-pull signal level in the second area is approximately 80% or more of the radial push-pull signal level in the first area. An optical recording medium manufacturing apparatus, comprising: 4. An apparatus according to claim 1, wherein said groove track forming means includes an average duty of said embossed pit row.
[%]), The depth of the embossed pit row (Ed [n
m]), the wavelength of the light beam (λ [nm]), the refractive index of the substrate of the optical recording medium (n [nm]), and the depth of the groove (Gd [nm]). 2
The optical recording medium manufacturing apparatus according to claim 3, wherein the embossed pit row is formed so as to substantially satisfy the following. [Formula 2] Duty = 0.04 (Ed−λ / 8n) ² + (−
0.07Gd ² + 6Gd-35.6) 5. An optical recording medium manufacturing method for manufacturing an optical recording medium capable of optically recording recording information using an optical disk master, wherein an optical recording medium for recording the recording information on the optical disk master is provided. A groove track forming step of forming a groove track including an area No. 1 and a second area in which predetermined data is formed as an emboss pit row and prevents reading of other data overwritten on the emboss pit row Wherein the groove track forming step forms the embossed pit row such that a radial push-pull signal level in the second area is approximately 80% or more of a radial push-pull signal level in the first area. A method for producing an optical recording medium, comprising: 6. The groove track forming step includes the step of forming an average duty of the embossed pit row.
[%]), The depth of the embossed pit row (Ed [n
m]), the wavelength of the light beam (λ [nm]), the refractive index of the substrate of the optical recording medium (n [nm]), and the depth of the groove (Gd [nm]). 3
6. The method according to claim 5, wherein the embossed pit row is formed so as to substantially satisfy the following. [Formula 3] Duty = 0.04 (Ed−λ / 8n) ² + (−
0.07Gd ² + 6Gd-35.6)