JPH08167170A - Optical disk and its manufacturing apparatus - Google Patents

Abstract

PURPOSE: To make it possible to display patterns of bright and large characters by fanning pits or grooves for display between recording tracks. CONSTITUTION: The character A which is the visible patterns is formed by the distributing state or distributing shape of the pits 6 for display on a substrate 4 of an information recording region 1a. The pits for information constituting the recording tracks are concentrically or spirally formed on the substrate 4 of the region 1a. The pits 6 are formed between the recording tracks consisting of the arrays of the pits 5 for information on the substrate 4. The pitch of the recording tracks is prescribed μm and the pits 6 exist in the intermediate therebetween. The pits 6 are formed between the pits 5 and are formed to the width and depth which are both smaller than the width and depth of the pits 5. The display patterns are formed by utilizing the differences in the diffraction angles of the reflected light between the parts formed with the pits or grooves for display and the other parts of the optical disk formed in such a manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc and its manufacturing apparatus.

[0002]

2. Description of the Related Art As a conventional optical disk, as shown in FIG. 1, an information recording area 1a and a label area 1 of an optical disk 1 are shown.
A pattern in which a visible character "A" or the like is formed in a region 1b between the c and the c is known, for example, from Japanese Patent Publication No. 5-797.

[0003]

However, since the display area of such a pattern is narrow, a sufficiently large pattern cannot be displayed and the amount of display information is limited. Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an optical disc capable of displaying a clear pattern of large characters and the like, and a recording apparatus for the master disc thereof.

[0004]

An optical disk according to the present invention is an optical disk having an information recording area in which concentric circular or spiral recording tracks composed of pit trains carrying information signals are formed. It is characterized in that display pits or grooves are formed between recording tracks so as to represent possible patterns.

Further, the optical disk manufacturing apparatus according to the present invention includes a turntable for holding and rotating an optical disk master having an unexposed photoresist layer on a recording surface, an exposure source for emitting a light beam, and rotation of the turntable. Rotation synchronizing signal generating means for generating a rotation synchronizing signal synchronized with the rotation synchronizing signal, information signal generating means for generating an information signal according to the rotation synchronizing signal, and a display pattern signal for forming a visible pattern according to the rotation synchronizing signal A pattern signal generating means for display for emitting a light beam, and a first modulating means for modulating the light beam according to the information signal to generate a modulated light beam for information.
Second modulation means for modulating the light beam in accordance with the display pattern signal to generate the display modulation light beam and the information and display modulation light beam are radiated to the recording surface while being separated from each other in the disk radial direction. It is characterized by comprising irradiation means.

[0006]

In the optical disc of the present invention having the above characteristics, visible pits or other patterns are displayed in the information recording area by the display pits or grooves formed between the recording tracks. Further, in the optical disk manufacturing apparatus of the present invention, the information and display modulated light beams obtained by modulating the light beam according to the information and display pattern signals are separated from each other in the disk radial direction. By simultaneously irradiating the resist layer formed on the recording surface of the optical disc master, the optical disc master can be produced in a short time.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows the structure of the optical disc according to the present invention.
The same parts as those in FIG. 1 are designated by the same reference numerals. Optical disc 1
As shown in FIGS. 2A and 2C, is composed of a substrate 4, a reflective layer 3, and a protective layer 2. Specifically, on one surface of the substrate 4, an information pit 5 that carries an information signal and forms a recording track, and a display pit 6 that forms a visible pattern are formed. And the protective layer 2 is formed on the reflective layer 3.

FIG. 2A shows a perspective view of the main part of the optical disc of the present invention. In the figure, a character "A" which is a visible pattern is formed on the substrate 4 of the information recording area 1a by the distribution state or distribution shape of the display pits 6. Although not shown, information pits forming recording tracks are formed in a concentric or spiral shape on the substrate 4 of the information recording area 1a. The arrow R indicates the radial direction.

FIG. 2B is an enlarged view of the portion B of FIG. 2A. Information pit 5 on substrate 4
Display pits 6 are provided between the recording tracks, each of which has a row of
Are formed. The pitch of the recording track is, for example,
It is 1.4 to 2.0 μm, and the display pit 6 is located in the middle of the recording track. The character "A" is displayed depending on the distribution state of the display pits 6.
The display pit 6 is formed longer in the track direction than the length of the information pit 5.

FIG. 2 (c) is a sectional view taken along line CC of FIG. 2 (b). As shown in the figure, display pits 6 are formed between the information pits 5. The width and depth of the display pit 6 are both smaller than the width and depth of the information pit 5. The reason will be described below. In the optical disc shown in FIG. 2, display pits 6 are formed between the tracks of the information pits 5, and the distribution shape is formed so as to correspond to the pattern of the visible letter “A”. This is a configuration for forming a possible pattern. On the other hand, the pattern portion of the character "A" may be so-called blank and the display pits may be formed around the pattern or in the entire area outside the pattern. In this case, for example, the display will be as shown in FIG. The solid line in FIG. 3 represents the display pit 6, and the information pits forming the recording track are omitted.

2 and 3, pits are formed in order to represent a visible pattern, but instead, a groove may be formed between tracks to display the visible pattern. good. Further, in each of the above-described embodiments, the character "A" is shown by the display pit, but the present invention is not limited to this. For example, it is possible to display a pattern such as graphics or photographs showing the content of the information signal recorded on the optical disc.

The physical shape of the display pit or groove is determined as follows. The frequency of the display pit or groove is 20 kHz, which is the upper limit of the frequency band of the tracking servo, and 1 which is the lower limit of the EFM audio signal.
Within the range of 96 kHz, it is possible to prevent interference due to display pits when reproducing information signals or performing tracking servo. Further, considering the influence of harmonics, the frequency band of the display pit or groove is 20 to
The frequency is preferably 100 kHz. Therefore, the length of the information pit is 0.5 to 2.5 μm, but the length of the display pit or groove is set to several tens to several hundreds μm corresponding to the frequency band. Also, in consideration of manufacturing restrictions of optical discs and the influence of crosstalk, display pits or grooves are formed in the middle between recording tracks, and the width and depth of the display pits or grooves are the information pits (width 0.4 to 0.6 μm, and depth of 1000 to 1500 angstroms) is preferably about half or less.

In the optical disc of the present invention, a display pattern is formed by utilizing the difference in the diffraction angle of the reflected light between the portion where the display pits or grooves are formed and the other portion. The principle will be explained. The incident angle of the incident light on the pit is θi, the wavelength of the incident light is λ, and the diffraction angle of the reflected light from the pits arranged in the disk radial direction is θd. First, when the display pits are not formed, the lights diffracted from the respective pits all have the same phase and strengthen each other to generate a strong diffracted light in the direction of θd1. There is a need. Here, the lattice constant is the recording track pitch P as shown in FIG. In addition, n is an integer.

[0014]

## EQU1 ## P (sin θi + sin θd1) = nλ For simplification, if the incident angle θi is 0 ° and n = 1 and it is considered as the first-order diffracted light, it can be expressed by the following formula 2.

[0015]

## EQU00002 ## Psin .theta.d1 = .lamda .. When this equation is summarized for .theta.d1, the following Equation 3 is derived.

[0016]

## EQU00003 ## .theta.d1 = sin.sup.- ¹ (.lamda. / P) On the other hand, when display pits are formed between recording tracks, the lattice constant is the pitch between the information pits and the display pits as shown in FIG. Which is P / 2. Therefore, θ
In order for strong diffracted light to be generated in the d2 direction, it is necessary to satisfy the following formula 4.

[0017]

## EQU00004 ## (P / 2) .multidot. (Sin.theta.i + sin.theta.d2) = n.lamda. For simplification, if the incident angle .theta.i is 0.degree.

[0018]

## EQU00005 ## (P / 2) .sin .theta.d2 = .lamda .. By summarizing this equation for .theta.d2, the following Equation 6 is derived.

[0019]

## EQU00006 ## .theta.d2 = sin.sup.- ¹ (2.lamda./P) As is apparent from the equations 3 and 6, the diffraction angle .theta.d2 with the display pits is about twice the diffraction angle .theta.d1 without the display pits. Becomes Therefore, the reflected diffracted light when there is a display pit has a stronger color on the short wavelength side than the reflected diffracted light when there is no display pit. It can be visually identified. That is, when the display pit is formed, it is displayed as a strong blue rainbow color as compared with the case where the display pit is not formed.

Next, an embodiment of an optical disk manufacturing apparatus according to the present invention will be described with reference to the drawings. FIG. 5 shows an embodiment of an optical disk manufacturing apparatus according to the present invention. The manufacturing apparatus has the following configuration. An Ar laser 11 is used as a light source that emits a light beam, and an information signal generator 12 is used as an information signal generating unit that emits an information signal. For displaying a pattern signal for display for forming a visible pattern. As the pattern signal generating means,
The display pattern generator 13 is used.

As the first and second modulating means, an A / O modulator (Acoustic Optical Modulator) 16a is used.
And 16b are used respectively. As the irradiation means, a mirror 17a, a beam splitter 17b, a beam expander 18, a mirror 19 and an objective lens 20 are used. The optical head 21 including the beam expander 18, the mirror 19 and the objective lens 20 has a feed motor 22.
Is driven in the direction of the arrow (radial direction of the optical disc).

The turntable 7 also holds the recording disk master 1 having a positive photoresist layer having exposed areas as pits. The turntable 7 is rotationally driven by a spindle motor 8. A rotation synchronizing pulse generator 9 is used as a rotation synchronizing signal generating means for generating a rotation synchronizing pulse synchronized with the rotation of the turntable 7. Further, the clock generator 10 generates a clock pulse according to the rotation synchronization pulse.

The recording operation is performed as follows. First,
The light beam emitted from the Ar laser 11 is reflected by the mirror 14
Is reflected by the beam splitter 15a, is incident on the beam splitter 15a, and is split into a transmitted light beam and a reflected light beam. On this occasion,
The beam splitter 15a is adjusted so that the transmitted light beam and the reflected light beam have the same light quantity. The transmitted light beam enters the A / O modulator 16a, and the reflected light beam enters the A / O modulator 16b after being reflected by the mirror 15b.

Then, the rotation synchronizing pulse generator 9 outputs a rotation synchronizing pulse synchronized with the rotation of the turntable 7, and the clock generator 1 is responsive to the rotation synchronizing pulse.
0 emits a clock pulse. The information signal generator 12 is
For example, an information signal as shown in FIG. 6A is emitted in synchronization with the clock pulse. The A / O modulator 16a is
The transmitted light beam is modulated in accordance with the information signal, and thereby the information modulated light beam is generated with the intensity as shown in FIG. 6C.

On the other hand, in response to the rotation synchronizing signal generated from the rotation synchronizing pulse generator 9, the display pattern generator 13
6 to form a pattern visible from FIG.
A display pattern signal as shown in (b) is emitted.
The A / O modulator 16b modulates the reflected light beam according to the display pattern signal, and thereby generates the display modulated light beam with the intensity as shown in FIG. 6D. The intensity of the modulated light beam for display is approximately 1 of the intensity of the modulated light beam for information.
/ 2 or less. An E / O modulator may be used instead of the A / O modulator.

Here, the depth and width of the display pits formed in the photoresist layer are the depth and width of the information pits, with the amplitude of the display pattern signal being approximately 1/2 or less of the amplitude of the information signal. Of about 1/2 or less. The pit length is adjusted by the pulse widths of the display pattern signal and the information signal. Next, the modulated light beam for information is transmitted to the mirror 1
7a, beam splitter 17b, beam expander 1
8, through the mirror 19 and the objective lens 20, the photoresist layer of the optical disc master 1 is irradiated and information pits are recorded.

On the other hand, the modulated light beam for display has its optical axis aligned substantially parallel to the modulated light beam for information, and the beam splitter 17b, the beam expander 18, and the mirror 19 are provided.
Then, the photoresist layer of the optical disc master 1 is irradiated with the light through the objective lens 20, and the display pits are recorded. At this time, in order to form the display pits between the recording tracks, the information-modulated light beam and the display-modulated light beam are mutually radiated on the recording surface of the optical disc master by approximately ½ recording track pitch in the disc radial direction. Separated.

The feed motor 22 is used for the optical disc master 1.
The optical head 21 is moved in the direction of the arrow (radial direction of the optical disc) so that recording tracks are formed at the correct pitch in accordance with the rotation of the. According to the optical disk manufacturing apparatus having such a configuration, it is possible to simultaneously record information pits that carry information signals and display pits that form a visible pattern at regular intervals.

Further, although the depth of each of the display pits is made constant in the present embodiment, the depth of each of the display pits may be changed. It is well known that a large number of optical discs can be easily obtained by obtaining a replica using the optical disc obtained by the above-mentioned optical disc manufacturing apparatus as a master.

[0030]

According to the optical disc of the present invention,
The display pits or grooves formed between the recording tracks of the optical disc form a visible pattern in the information recording area, so that a clear and sufficiently large pattern of characters or the like can be displayed. Further, since the display pits or the grooves are formed between the recording tracks, a visible pattern can be formed without reducing the recording density of a normal information signal.

Further, in the optical disk manufacturing apparatus of the present invention, the information and display modulated light beams obtained by modulating the light beam in accordance with the information and display pattern signals are provided in the disk radial direction. Since the photoresist layer of the optical disc master, which is the recording surface, is irradiated at the same time with a slight separation, it is possible to form the display pits forming a visible pattern between the recording tracks in a short time.

[Brief description of drawings]

FIG. 1 is a schematic view of a conventional optical disc.

2 is an embodiment of an optical disc according to the present invention, FIG. 2 (a) is a perspective view showing the outline of the main part thereof, FIG. 2 (b) is an enlarged view of portion B of FIG. 2 (a), (C) is FIG. 2 (b)
FIG. 6 is a cross-sectional view taken along the line CC of FIG.

FIG. 3 is another embodiment of the optical disc of the present invention.

FIG. 4 is a diagram showing a structure of an optical disk display pit and an information pit of the present invention.

FIG. 5 is a schematic block diagram showing an embodiment of an optical disc manufacturing apparatus according to the present invention.

6 is a diagram showing an example of a signal waveform of each part of the apparatus of FIG.

[Explanation of symbols for main parts]

 1 Optical Disc 1a Information Recording Area 1c Label Area 5 Information Pit 6 Display Pit 7 Turntable 8 Spindle Servo Motor 11 Ar Laser 14, 15b, 17a, 19 Mirror 15a, 17b Beam Splitter 16a, 16b A / O Modulator 12 Information Signal generator 13 Display pattern generator 21 Optical head 20 Objective lens 9 Rotation synchronization pulse generator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yu Murakami 2680 Nishi Hanawa, Tatomi-cho, Nakakoma-gun, Yamanashi Prefecture Pioneer Video Co., Ltd.

Claims (6)

[Claims] 1. An optical disc having an information recording area in which concentric circular or spiral recording tracks made up of pit rows carrying information signals are formed, and the recording is performed so that a visible pattern is displayed in the information recording area. An optical disk having display pits or grooves formed between tracks. 2. The pattern according to claim 1, wherein the pattern is formed by a distribution shape of the display pits or grooves or a distribution shape of a portion other than the display pits or grooves. optical disk. 3. The optical disc according to claim 1, wherein the display pits or grooves have a width and a depth that are approximately ½ or less of the pits that carry the information signals. 4. The optical disk according to claim 1, wherein a frequency of the display pit or groove is higher than a tracking frequency band of a tracking servo and lower than a frequency band of the information signal. 5. A turntable for holding and rotating an optical disk master having an unexposed photoresist layer on a recording surface, a light source for emitting a light beam, and a rotation for issuing a rotation synchronizing signal in synchronization with the rotation of the turntable. Sync signal generating means, information signal generating means for issuing an information signal in response to the rotation synchronizing signal, and display pattern signal generating for issuing a display pattern signal for forming a visible pattern in response to the rotation synchronizing signal Means for modulating the light beam according to the information signal to generate a modulated light beam for information, and modulating the light beam according to the display pattern signal for modulating the light beam for display And a light for irradiating the recording surface with the information and display modulated light beams separated from each other in the disk radial direction. Manufacturing device of an optical disk, characterized by comprising a means. 6. The modulated light beam for information and display comprises:
6. The optical disk manufacturing apparatus according to claim 5, wherein spots are formed on the recording surface in the disk radial direction and are separated from each other by a 1/2 track pitch.