JP4812103B2 - Optical disk manufacturing apparatus and manufacturing method - Google Patents

Description

  The present invention relates to an optical disc manufacturing apparatus and manufacturing method that include an optical recording area in which pits or grooves are formed on at least one surface of a signal substrate, and that can record or reproduce information by laser light.

  In recent years, in the field of data recording, development related to an optical data recording system (optical disc) has progressed, and it has been put to practical use in a wide range of fields from industrial use to consumer use. This optical data recording method has the advantage of being able to record / reproduce data with high recording density in a non-contact state, and compatible with each memory form such as read-only type, write-once type, and rewritable type. It is possible to realize an inexpensive and large-capacity data file.

  Particularly, a DVD (Digital Versatile Disc) widely used in the present situation has a structure in which two substrates having a thickness of about 0.6 mm are bonded together with an adhesive with the signal recording surface inside. Further, a laser beam having a shorter wavelength of 650 nm than that of an initial CD (Compact Disc) is used, and the numerical aperture (NA = Numerical Aperture) of the objective lens constituting the optical system is also increased.

  Further, recently, with the practical application of HDTV (High Definition Television), for example, the demand for higher density has increased in order to record or play back the video, and the higher density positioned in the next generation of DVD. Recording optical discs have been proposed. According to this, in order to cope with high-density recording, it is necessary to make the condensing spot diameter of the laser beam for recording / reproducing information smaller. Here, when the wavelength of the laser beam is λ and the numerical aperture of the objective lens is NA, it is known that the focused spot diameter of the laser beam is proportional to λ / NA.

  Therefore, in order to reduce the focused spot diameter of the laser beam, it is necessary to shorten the wavelength λ of the laser beam and increase the numerical aperture NA of the objective lens as much as possible. For this purpose, there is a structure of an optical disk that uses a blue (blue) laser beam (wavelength of, for example, 410 nm) having a wavelength shorter than that of the laser beam used for recording or reproducing on the DVD described above. Proposed.

  On the other hand, when attention is paid to the coma aberration of the optical system, it is known that this coma aberration increases in proportion to the substantial thickness of the disk substrate and in inverse proportion to the wavelength λ of the laser beam. Therefore, in the case where a laser beam having an extremely short wavelength is used as in the blue laser described above, it is necessary to make the substantial thickness of the disk substrate thin in order to suppress an increase in coma aberration. Arise.

  Therefore, according to the above-described optical disc using a blue laser (Blue Lay Disc), a method of irradiating a laser beam from the recording layer side opposite to the substrate has been proposed, contrary to the conventional DVD configuration. In order to protect the recording layer, a configuration is proposed in which a cover layer (protective layer) having a thickness of about 0.1 mm (100 μm) is provided on the outer side (the side irradiated with the laser beam) from the recording layer. According to this, the laser beam passes through the cover layer having a thickness of about 0.1 mm and is irradiated onto the recording layer.

  FIG. 1 schematically shows an enlarged cross-sectional view of a part of an optical disk using the blue laser described above. Reference numeral 1 in FIG. 1 indicates a disk substrate on which a large number of pits 1 a are formed, and reference numeral 2 indicates a light reflecting film that covers the formation surface of the pits 1 a on the disk substrate 1. The pit 1a and the reflective film 2 constitute the recording layer 3 described above. In order to protect the recording layer 3, a cover layer (protective layer) 4 having a thickness of about 0.1 mm is formed on the recording layer 3. It is superimposed on the top. On the other hand, reference numeral 5 denotes an objective lens constituting the optical system, and the laser beam passing through the objective lens 5 is transmitted through the cover layer 4 and irradiated onto the recording layer 3 as described above. .

  In the optical disk shown in FIG. 1, since the signal reading operation is performed from the cover layer 4 side as described above, the management of the thickness of the cover layer is a very important issue in relation to the above-described coma aberration. That is, a high degree of uniformity is required for the thickness of the cover layer. Therefore, several proposals have been made to form the cover layer with a uniform thickness.

  A typical means in a conventional method for forming a cover layer is a spin coating method in which an ultraviolet curable resin (UV curable resin) is spread toward the outer periphery of the disk by centrifugal force by rotating the disk substrate. Thereafter, the cover layer is formed on the disk substrate surface by irradiating with ultraviolet rays.

  FIG. 2 schematically shows a basic example of this, and as shown in FIG. 2A, the UV curable resin 12a is formed from the nozzle 13 near the center hole 11a of the disk substrate while rotating the disk substrate 11 at a low speed. To discharge. Subsequently, as shown in (B), the disk substrate 11 is rotated at a high speed, and the UV curable resin 12a discharged near the center hole 11a of the disk substrate is spread to the outside of the disk substrate by centrifugal force, so that the resin 12a is spread. The entire surface of the disk substrate is coated, and the cover layer 12 is formed on the disk substrate 11 by irradiating with ultraviolet rays in this state.

  According to the spin coating method of the UV curable resin shown in FIG. 2, when the UV curable resin is coated to the outermost periphery of the substrate surface by centrifugal force, the film thickness of the resin already increases from the inner peripheral side to the outer peripheral side of the disc. In this state, when the ultraviolet ray is irradiated, there is a problem that the film thickness becomes non-uniform.

  Therefore, means for discharging the UV curable resin 12a from the nozzle 13 in the vicinity of the center of the disk with the center cap 14 mounted in the center hole 11a of the disk as shown in FIG. 3, and the center of the disk as shown in FIG. Means for applying a seal 15 so as to close the hole 11a and discharging the UV curable resin 12a from the nozzle 13 near the center of the disk, and a disk with a spool 16 that does not cut the center hole 11a of the disk as shown in FIG. In this state, it has been proposed to make the film thickness uniform by adopting a means for discharging the UV curable resin 12a from the nozzle 13 near the center of the disk.

For example, the film thickness uniformizing means shown in FIG. 3 is disclosed in Patent Documents 1 and 2 shown below.
Japanese Patent Laid-Open No. 2003-242688 JP 2004-95108 A

  By the way, in the conventional means for uniformizing the film thickness, when the UV curable resin is spin coated, the film thickness is reduced by devising the discharge position of the UV curable resin and the injection amount of the UV curable resin with respect to the disk substrate. It is trying to make it uniform. For this reason, in the spin coating process, a cover or the like that closes the center hole of the disk is prepared, and it is inevitable that the structure of the apparatus itself is complicated and expensive.

  Further, since the irradiation intensity of the ultraviolet rays applied to the UV curable resin is constant regardless of the inner and outer circumferences of the disk, the UV curable resin applied on the disk cannot be selectively cured. For this reason, it has the fault that it is difficult to find the conditions for making the film thickness uniform.

  The present invention has been made by paying attention to the problems of the conventional one described above, and by devising to change the irradiation region of the ultraviolet ray with respect to the UV curable resin coated on the disk substrate with time, the cover layer is formed. It is an object of the present invention to provide an optical disk manufacturing apparatus and a manufacturing method that can be formed in a more uniform thickness.

An optical disk manufacturing apparatus according to the present invention, which has been made to solve the above-mentioned problems, is a thin film with respect to a disk substrate on which an optical recording area is formed in a disk shape having a radius r , as defined in claim 1. An optical disk manufacturing apparatus for forming a layer, which is rotationally driven with the disk substrate mounted thereon, and capable of controlling the rotational speed of the disk, and is mounted on the rotational drive means. An application means for applying an ultraviolet curable resin as a material for the thin film layer to the disk substrate, an ultraviolet irradiation means for irradiating the disk substrate coated with the ultraviolet curable resin by the application means, ultraviolet light irradiation means and the arranged light-shielding mask between the mounted disk substrate to the rotary drive means, and said ultraviolet light irradiation means to said light-shielding mask di A moving means for enabling movement is provided between the click substrate, the maximum movement by said light-shielding mask large through-hole than the center hole of the disc substrate is formed in, and the moving means of the light shading mask The distance h is made larger than the value of the radius r, and an ultraviolet irradiation region irradiated on the disk substrate through the through hole of the light shielding mask by the movement of the light shielding mask by the moving means. The present invention is characterized in that it can be controlled in a range from the inner peripheral position of the disk substrate to the entire surface of the disk substrate .

According to a third aspect of the present invention, there is provided an optical disc manufacturing method, wherein the optical disk manufacturing apparatus according to the first aspect is used to form a thin film layer on the disk substrate on which the optical recording area is formed. A method of manufacturing an optical disc, the step of applying an ultraviolet curable resin as a material for the thin film layer to a disk substrate in a rotationally driven state, and the ultraviolet curable resin by rotating the disk substrate at a higher speed. In the process of expanding the disk substrate toward the outer periphery of the disk substrate, an ultraviolet irradiation process is performed in which the ultraviolet irradiation area of the disk substrate from the ultraviolet irradiation means gradually concentrically extends from the inner periphery to the outer periphery of the disk substrate. It has a feature in that.

  Hereinafter, an optical disk manufacturing apparatus and method according to the present invention will be described based on the embodiment shown in FIGS. 6A to 6C. 6A to 6C exemplify a case where a cover layer covering the optical recording layer formed on the disk substrate is formed as already described with reference to FIG.

  As described above, the disk substrate 11 on which the optical recording layer is formed is mounted on a spin stand 21 that constitutes a disk rotation driving means as shown in FIG. 6A. The spin stand 21 has a boss 21a formed at the center of rotation on the upper surface thereof, and the disk substrate 11 is mounted on the spin stand 21 with the center hole 11a fitted into the boss 21a. In this state, the UV curable resin 12 a is discharged onto the disk substrate 11 from the nozzle 13 that functions as a UV curable resin coating means.

  At this time, the UV curable resin from the nozzle 13 is discharged (applied) to a position slightly outside the center hole 11 a of the disk substrate 11. The spin stand 21 is configured so as to be able to control the number of rotations thereof. At this time, the number of rotations is driven at a relatively low speed of about 1 to 300 rpm. Thereby, the UV curable resin discharged from the nozzle 13 is applied in a ring shape to the inner peripheral position of the disk substrate 11.

  Subsequently, the nozzle 13 is retracted from the upper part of the spin stand 21, and the unit of the ultraviolet irradiation means 22 and the light shielding mask 23 is moved to the upper part of the spin stand 21 as shown in FIG. 6B. For example, a metal halide lamp is provided in the ultraviolet irradiating means 22 and is positioned directly above the disk substrate 11 mounted on the spin stand 21 and irradiates the entire surface of the disk substrate 11 with ultraviolet rays as indicated by reference numeral UV. The optical characteristics are set so that

The light shielding mask 23 is formed in a disk shape, for example, and is disposed between the ultraviolet irradiation means 22 and the disk substrate 11 on the spin stand 21. The mask 23 is configured to move in the vertical direction between the ultraviolet irradiation means 22 and the disk substrate 11 by a moving means including a support member 24. The light shielding mask 23 is formed with one circular through hole 23a through which the ultraviolet ray UV from the ultraviolet irradiation means 22 passes toward the disk substrate 11, and the diameter of the through hole 23a is set to The diameter is set slightly larger than the center hole 11a (diameter 15 mm) of the substrate 11.

The through hole 23a of the light shielding mask 23 has the center position positioned on a vertical line connecting the ultraviolet irradiation means 22 and the center portion of the disk substrate 11 on the spin stand 21 so that the support member 24 is positioned. It is comprised so that it may move to a perpendicular direction by the moving means to include .

Therefore, as shown in FIGS. 6B to 6C, when the light shielding mask 23 is moved from the position closest to the disk substrate 11 (lowest position) to the position close to the ultraviolet irradiation means 22 (highest position), the through-hole 23a is used. The irradiation region of the ultraviolet rays UV irradiated to the disk substrate is gradually concentric toward the outer periphery of the disk substrate 11 from the inner peripheral position of the disk substrate 11, that is, the region slightly including the outer side of the center hole 11a. The area is expanded so as to spread. Then, in the state shown in Figure 6C in which the mask 23 is moved to the nearest (highest position) of the ultraviolet irradiation unit 22, it is made as ultraviolet light is irradiated to the entire surface of the disc substrate 11.
That is, the ultraviolet irradiation region irradiated to the disk substrate 11 through the through hole 23a can be controlled in a range from the inner peripheral position of the disk substrate 11 to the entire surface of the disk substrate 11. Has been.

  As already described with reference to FIG. 6A, in a state where the UV curable resin is applied in a ring shape to the inner peripheral position of the disk substrate 11, the unit of the ultraviolet irradiation means 22 and the light shielding mask 23 configured as described above is the disk substrate. Move to the top of 11. Then, the disk substrate 11 is subjected to high speed rotation (300 to 10000 rpm) this time by driving the spin stand 21. As a result, spin coating is performed in which the UV curable resin is subjected to centrifugal force and spreads toward the outer periphery of the disk substrate 11.

  At this time, as shown in FIG. 6C, the light shielding mask 23 gradually moves (rises) from the position closest to the disk substrate 11 to the position closest to the ultraviolet irradiation means 22 as indicated by an arrow. Thereby, as described above, the irradiation area of the ultraviolet ray on the disk substrate 11 from the ultraviolet irradiation means 22 is gradually expanded concentrically from the inner periphery to the outer periphery of the disk substrate.

  Accordingly, the UV curable resin is subjected to centrifugal force and is spread toward the outer periphery of the disk substrate 11, and the ultraviolet irradiation region is gradually expanded concentrically, so that the resin is sequentially extended from the inner periphery to the outer periphery of the substrate 11. Cured. Thereby, a thin film layer having a uniform thickness over the entire surface of the disk substrate, that is, the cover layer 12 can be formed on the upper surface of the disk substrate 11.

  In other words, in the case of irradiating ultraviolet rays after spin coating the resin as in the past, the thickness of the cover layer is uneven due to the resin being moved to the outer periphery of the disk substrate by spin coating. This can be effectively corrected by adopting the above-mentioned means.

  In the apparatus according to the present invention, as shown in FIG. 6C, the maximum moving distance h of the light shielding mask 23 with respect to the disk substrate 11 is controlled to be larger than the value of the radius r of the disk substrate. . By adopting such a configuration, it is possible to widely control the irradiation intensity of ultraviolet rays applied to the disk without controlling the intensity of the light source.

  The above explanation shows an example in which a cover layer (protective layer) having a thickness of about 0.1 mm for protecting the recording layer is formed to have a uniform thickness in an optical disc (Blue Lay Disc) using a blue laser. However, the present invention can also be suitably employed when forming an intermediate layer in a two-layer disc structure such as a DVD-R (Digital Versatile Disc-Recordable).

It is sectional drawing which expanded and showed a part of optical disk using a blue laser. It is the schematic diagram which showed the example of the conventional spin coat method. It is the schematic diagram which showed the conventional method of correcting the problem by the spin coat method shown in FIG. It is the schematic diagram which showed the other conventional method similarly. It is the schematic diagram which showed the other conventional method similarly. It is a schematic diagram explaining the application | coating process in the manufacturing method of the optical disk concerning this invention. It is a schematic diagram explaining the irradiation process of an ultraviolet-ray similarly. It is a schematic diagram explaining the movement state of the light shielding mask similarly in the irradiation process of an ultraviolet-ray.

Explanation of symbols

11 Disc substrate 11a Center hole 12 Cover layer (thin film layer)
12a UV curable resin 13 Nozzle 21 Spin stand 21a Boss 22 UV irradiation means 23 Light shielding mask 23a Through hole 24 Support member UV UV

Claims (5)

An optical disk manufacturing apparatus for forming a thin film layer on a disk substrate in which an optical recording area is formed in a disk shape having a radius r,
Rotating and driving the disk substrate in a state of being mounted, and a disk rotation driving means capable of controlling the number of rotations;
Application means for applying an ultraviolet curable resin, which is a material of the thin film layer, to the disk substrate placed on the rotation driving means;
An ultraviolet irradiation means for irradiating the disk substrate coated with the ultraviolet curable resin by the application means with ultraviolet rays;
A light shielding mask disposed between the ultraviolet irradiation means and a disk substrate placed on the rotation driving means;
Moving means for allowing the light shielding mask to move between the ultraviolet irradiation means and the disk substrate;
Is provided,
A through hole larger than the central hole of the disk substrate is formed in the light shielding mask, and the maximum moving distance h by the moving means of the light shielding mask is made larger than the value of the radius r,
Due to the movement of the light shielding mask by the moving means, the irradiation region of the ultraviolet ray irradiated to the disk substrate through the through-hole of the light shielding mask extends from the inner peripheral position of the disk substrate to the entire surface of the disk substrate. An optical disc manufacturing apparatus characterized by being configured to be controllable over a wide range.   2. The ultraviolet irradiation area from the ultraviolet irradiation means passing through the through hole is configured to change concentrically on the disk substrate as the light shielding mask moves. An optical disk manufacturing apparatus described in 1. A method of manufacturing an optical disk, wherein the optical disk manufacturing apparatus according to claim 1 is used to form a thin film layer on a disk substrate on which an optical recording area is formed.
An application step of applying an ultraviolet curable resin, which is a material of the thin film layer, to the disk substrate in a rotationally driven state;
In the process of rotating the disk substrate at a higher speed to spread the ultraviolet curable resin from the inner periphery to the outer periphery of the disk substrate, the irradiation region of the ultraviolet rays from the ultraviolet irradiation means to the disk substrate is changed from the inner periphery to the outer periphery of the disk substrate. UV irradiation process gradually spreading concentrically toward the
A method of manufacturing an optical disc, characterized in that   The position of the light shielding mask is moved from the disk substrate side to the ultraviolet irradiation means side, so that the ultraviolet irradiation region is gradually expanded concentrically from the inner periphery to the outer periphery of the disk substrate. 3. A method for producing an optical disk as described in 3. 5. The method of manufacturing an optical disk according to claim 3, wherein the thin film layer is a cover layer that covers an optical recording layer formed on the disk substrate.

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