JPH07110968A - Apparatus and method for polishing of tape for optical-disk master disk - Google Patents

Abstract

PURPOSE:To polish a tape always to a definite face roughness even when the hardness and the temperature in the polishing operation of an optical-disk master disk are changed. CONSTITUTION:The polishing position of an optical-disk master disk 30 is detected by a position detection part 46. The number of revolutions of the optical-disk master disk 30 or the feed speed of a polishing tape is changed by a detection signal in a rotation part 43 according to a polishing position so that the relative speed of the polishing tape and the optical-disk master disk is made definite. In addition, light is shone at the polishing face of the optical-disk master disk 30, its reflected light is detected, a polishing pressure is changed automatically by a detection signal, and the polishing time is controlled. Thereby, an irregularity in the thickness due to the polishing operation of the optical-disk master disk can be eliminated, and a polishing speed can be increased remarkably. In addition, irrespective of the hardness and the temperature in the polishing operation of the optical-disk master disk, the tape can be polished always to a definite polishing face, and the optical-disk master disk whose reliability is high and whose accuracy and quality are always high can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an optical disc master for producing optical discs such as video discs, digital audio discs, still images and document files.

[0002]

2. Description of the Related Art Generally, an optical disc is promising as an information medium due to its extremely high information density, large S / N ratio and little noise, and is commercialized as a video disc for recording and reproducing digital signals. In recent years, research and development has been carried out as an optical disc. The most common method for producing this optical disk is a method in which an optical disk master called a stamper is used to reproduce by molding such as injection or injection compression.

A conventional optical disk master tape polishing apparatus and a conventional polishing method for manufacturing an optical disk master necessary for manufacturing an optical disk will be described below with reference to the drawings. 10 and 11 (a) to (i) show a conventional optical disc master and a conventional optical disc manufacturing method. Further, FIG. 12 is a block diagram of a conventional tape polishing apparatus for an optical disk master, and FIG. 13 is a table showing the difference in polishing rate due to the difference in the type of polishing tape when polishing is performed using this polishing apparatus. 14 is the number of rotations at each polishing position of the optical disc master in the conventional optical disc master polishing apparatus, and FIG. 15 is a table showing the thickness distribution of the optical disc master after polishing. In FIG. 10, 1 is a glass substrate, 2 is a resist film, 3 is a recording laser beam, 4 is a recorded signal portion, 5 is a conductive thin film, 6 is an electroformed plating film,
Reference numeral 7 is an optical disk master called a stamper, 8 is a disk substrate, 9 is a thin film for reflection or recording, 10 is a protective film for protecting the thin film, and 11 is an optical disk. 10 and 11, (a) is a resist film forming step, (b) is an exposure recording step, (c) is a developing step,
(D) is a conductive thin film forming step, (e) is an electroforming plating step,
(F) Back surface polishing step and inner / outer peripheral processing step of optical disk master, (g) forming step, (h) thin film forming step,
(I) is a protective film forming step. In FIG. 12, 12 is an optical disk master, 13 is a tape mounting reel, and 14 is a tape mounting reel.
Is a tape take-up reel, 15 is a tape feed roller, 16 is a polishing contact roller, 17 is a tape take-up roller, 18 is a tape fixing base for fixing the tape reel and roller, and 19 is a feed screw. , 20 is a feed motor, 21 is a rotary table, and 22 is a rotation motor. In order to manufacture an optical disk master called a stamper 7 , as shown in FIGS. 10 and 11, first, in the resist film forming step (a), the resist film 2 is formed on the glass substrate 1 by a spin method or the like, and then exposed. In the recording step (b), the signal is exposed and recorded with the recording laser beam 3, and in the developing step (c), the signal portion 4 is formed.
Next, in the conductive film forming step (d), a conductive thin film 5 of nickel or silver is formed to a thickness of 50 to 100 nm by a sputtering method or the like, and in the electroforming plating step (e), electroforming plating is performed on the nickel to form nickel. Plating film 6 0.2-0.4
After being formed with a thickness of mm, the resist film is peeled off from the glass substrate and the resist film is removed by washing or the like, and the back surface is polished in the back surface polishing step (f) so that this optical disk master fits the molding machine mold at the time of molding. An optical disk master 7 called a stamper is completed by polishing to a surface roughness of 1 μm or less and further cutting the inner and outer circumferences according to the mold. To produce an optical disk from the optical disc master 7 further molding process using the optical disc master 7 (g)
Then, a disc substrate 8 on which signals are transferred is formed by molding with a resin material such as polycarbonate or acrylic, and a thin film 9 for reflection or recording is formed on the signal surface of the disc substrate 8 in the thin film forming step (h). The optical disc 11 is completed by forming the protective film 10 with a thickness of several μm to several tens of μm in the protective film forming step (i).
In order to polish the back surface of this optical disk master for mounting on the mold, a tape polishing apparatus for an optical disk master as shown in FIG. 12 is used, and first, the optical disk master 12 is placed on the rotary table 21 with the back surface being the polishing surface facing upward. , The polishing tape is mounted on the tape mounting reel 13 mounted on the tape fixing base 18, wound on the polishing contact roller 16 via the tape feeding roller 15, and further wound on the tape winding roller 17 via the tape winding roller 17. It is arranged to be wound around the take-up reel 14. Next, the rotation motor 2
2 rotates the rotary table 21 to rotate the optical disk master 12, and the tape fixing base 18 to the feeding motor 2
By pressing the polishing contact roller 16 against the optical disk master 12 while winding the polishing tape with the tape winding roller 15 and the tape winding reel 13 while moving in the radial direction of the optical disk master 12 with 0 and the feed screw 19, The master disc of an optical disc is polished with a polishing tape. In this polishing, the optical disc master is rotated at a constant rotation speed (constant angular velocity) of about several hundred revolutions / minute, and the polishing tape is fed at a constant speed of about several tens cm / min. 400 optical disk master 12 here
FIG. 13 shows the relationship between the polishing time and the polishing amount when polishing the polishing tape at a speed of 50 cm / min and the tape fixing base 18 at a speed of 600 cm / min by rotating at a speed of revolutions / minute. That is, the amount of polishing, that is, the polishing rate varies depending on the type of the polishing mesh of the polishing tape, and the surface roughness improves as the polishing is performed, so that the polishing rate dramatically decreases after a certain period of time. Further, since the rotation speed of the optical disk master is constant, the polishing contact roller 1
The relative speed of the optical disk master viewed from 6 changes as shown in FIG. 14 depending on the polishing position, that is, the radial position of the optical disk master. For this reason, the polishing speed and the polishing amount of the optical disk master change depending on the radial position, and as shown in FIG. 15, there is a difference of about 5 μm between the inner and outer circumferences of the optical disk master. That is, the thickness of the optical disc master after polishing is 300 μm at the inner peripheral portion.
Then, it becomes about 295 μm in the outer peripheral portion. Next, since the polishing is performed by time management, the polishing is automatically terminated at a preset time regardless of the polishing state of the polishing surface.

[0004]

However, in the above-mentioned structure, since the relative speed of the polishing tape and the optical disc master differs depending on the polishing position, the polishing amount of the optical disc master varies depending on the radial position, resulting in uneven thickness of the optical disc master. Occur. Further, since the optical disc master is polished by time management, if the hardness of the optical disc master or the temperature during polishing changes, the polishing rate changes, and the surface roughness and thickness after polishing also change for each polishing. Therefore, when molding is performed using the optical disk master, unevenness in the thickness of the optical disk substrate obtained by molding occurs, and it also affects the molding conditions during molding, resulting in transfer defects, distortion, or deterioration of birefringence. It will be easier.

In view of the above-mentioned conventional problems, the present invention has a very high reliability by making it possible to polish the back surface of the optical disk master with a uniform thickness and a surface roughness with a constant accuracy. The present invention provides a tape polishing apparatus for an optical disc master and a polishing method for the same, which can produce a high-quality optical disc master.

[0006]

In order to solve the above problems, a tape polishing apparatus for an optical disk master and a method of polishing the same according to the present invention detect a polishing position of an optical disk master and detect the number of rotations of the optical disk master according to the polishing position. By changing the feed rate of the polishing tape, the polishing tape and the polishing surface of the optical disc master are controlled to always have a constant speed, and during polishing, light such as a laser is projected onto the polishing surface and the reflected light is measured. By measuring the state of the polishing surface, that is, the state of the surface roughness of the polishing surface, the pressure of the polishing tape pressed against the optical disc master is changed according to the value, and the polishing time is controlled by the magnitude of the reflected light measured. I decided to do it.

[0007]

According to the present invention, the amount of polishing and the polishing speed can be made constant at any polishing position of the optical disk master by the above-mentioned structure, so that the unevenness of the thickness of the optical disk master due to the polishing can be eliminated and the optical disk master can be used. The polishing time can be greatly shortened by changing the pressure of the polishing tape to be pressed according to the state of the polishing surface, and because the polishing time is controlled depending on the state of the polishing surface, it is possible to always achieve a constant surface roughness. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a polishing apparatus for an optical disk master and a polishing method therefor according to the present invention will be described in detail below with reference to the drawings. 1 is a block diagram of a tape polishing apparatus for an optical disk master according to the first embodiment of the present invention, and FIG. 2 is a front view of a polishing head portion of the tape polishing apparatus for an optical disk master according to the first embodiment of the present invention. 3A and 3B are a side view and a side view of a polishing tape portion of a tape polishing apparatus for an optical disc master according to a first embodiment of the present invention, and FIG. 4 is a side view of an optical disc master according to a first embodiment of the present invention. 5 is a table showing the number of rotations with respect to the polishing position, FIG. 5 is a table showing the thickness distribution of the optical disk master after polishing, and FIG. 6 is a surface roughness of the polished surface and the reflectance of the surface when the optical disk master is polished. 7 is a table showing the relationship of the surface roughness of the polishing surface with respect to the polishing time of the optical disk master, and FIG. 8 is a table showing the reflection of the polishing surface of the optical disk master in the first embodiment of the present invention. Research on rate A table showing the pressure for pressing the use contact roller, FIG. 9 is a table showing the first polishing time and the polishing amount of the relationship in the embodiment of the present invention. In FIG. 1, reference numeral 30 is an optical disk master, 35 is a polishing tape portion including a tape mounting reel 31, a tape winding reel 32, a tape feeding roller 33, and a tape winding roller 34, and 36 is a polishing tape portion. It is a tape fixing base for fixing 3
Reference numeral 9 is a polishing tape feeding unit composed of a feed screw 37 for moving the tape fixing base and a feeding motor 38, and 43 is a rotary table 40, a rotation motor 41, and a rotation control device 4.
2 is a rotating part, and 46 is a position detecting sensor 4
4 and a position detection unit consisting of the position detecting device 45, 49
Is a polishing head portion comprising a contact roller unit 47 and an air pressure controller 48 for controlling the pressure of the contact roller, and 52 is a laser 50 for measuring the amount of reflected light and a light receiving sensor 51 for receiving the reflected light. a reflected light measuring unit consisting, 56 reflected light quantity measuring instrument 53
And a reflected light quantity setting device 54 for setting in advance and a comparator 55 for comparing them. In FIG. 2, reference numeral 57 is a contact roller, 58 is a roller fixing base, 59 is an air cylinder for applying pressure to the roller head, and 60 is an air supply pipe for supplying air to the air cylinder. In FIG. 3, 61 is a take-up reel motor for taking up the polishing tape, and 62 is a tape take-up roller motor for taking up the polishing tape. This optical disk master tape polishing apparatus detects the position of the tape fixing base 36, which fixes the polishing tape portion and the contact roller unit for polishing, with a position detecting sensor 44 such as a linear encoder of the position detecting section 46. , The detected signal is converted by the position detection device 45 into a digital or analog signal proportional to the position, and this signal is sent to the rotation control device 42 of the rotation unit 43 , and the rotation control device 42 polishes the rotation motor by this signal. The rotation speed is set according to the position, and the relative speed between the optical disk master and the polishing tape is kept constant. Alternatively, the rotation speed of the polishing take-up reel motor 62 and the take-up roller motor 63 is changed according to the polishing position in response to a signal from the position detection device 45 to change the winding speed of the polishing tape, thereby changing the optical disc master and the polishing tape. The relative speed is kept constant. Further, the laser light of the laser 50 of the reflected light measuring unit 52 is applied to the polishing surface of the optical disc master 30, the reflected light is received by the light receiving sensor 51, and the reflected light amount measuring device 53 of the reflected light comparing unit 56 receives the reflected light. The signal is converted into a signal according to the amount of light. Then, the reflected light amount setter 54 is set so that the amount of reflected light necessary for comparison can be set in advance, and the signal measured by the reflected light amount measurer 53 and the value set by the reflected light amount setter 54 are compared by the comparator 55. Then, at the time of coincidence, a signal is sent from the comparator 55 to the rotation control device 42 of the rotary table and the control device of the polishing tape feed motor, and the polishing is automatically terminated by stopping each of them. Is. Also,
A signal detected by the reflected light amount measuring device 54 during polishing is sent to the air controller 48, and the pressure of the air supplied to the air cylinder 59 for the contact roller 57 is automatically changed according to this signal amount. is there. This is because the surface roughness of the polishing surface is improved as the polishing is performed and the friction coefficient of the polishing surface is decreased, so that the polishing pressure is increased accordingly. Here, based on the signal detected by the detection unit 46 , the optical disc master is set at 1 m / m as shown in FIG.
The linear velocity per second is controlled by the rotation control device 42, the polishing tape is fed at a constant speed of 50 cm / min, and the contact roller 15 is moved while moving the tape fixing base 18 in the radial direction at a speed of 500 cm / min. In the case of polishing by pressing at a pressure of 5 kg / cm ² , the thickness unevenness of the optical disk master after polishing could be kept within 1 μm for both the inner and outer circumferences, as shown in FIG. Further, the relationship between the surface roughness of the polished surface of the optical disk master and the reflectance is as shown in FIG. 6, and the relationship between the polishing time and the surface roughness of the polished surface when polishing is performed using a 2000-thick polishing tape is shown in FIG. 7 is as follows. Therefore, the pressure of the air supplied to the air cylinder 59 for the contact roller 57 is automatically obtained from the signal obtained by the reflected light amount measuring device 54 in FIG.
When the polishing was performed while controlling the pressure as shown in Fig. 9, the polishing rate could be remarkably increased as shown in Fig. 9.

[0009]

As described above, according to the present invention, the number of revolutions of the optical disk master or the speed of the polishing tape is changed according to the polishing position so that the relative speeds of the optical disk master and the polishing tape are always equal to each other. The entire polishing surface of the master can be polished under the same conditions. Therefore, the polishing amount of the optical disk master can be made uniform over the entire polishing surface, and unevenness in thickness after polishing can be eliminated and the surface can be finished in a uniform surface roughness state. It became so. Further, since the state of the polishing surface of the optical disc master is detected during polishing and the polishing time is controlled according to the surface roughness of the polishing surface, the state of the polishing surface is always constant even if the hardness of the optical disc master changes ( It became possible to polish to surface roughness. Further, during polishing, the pressure of the polishing tape pressed against the optical disk master is changed according to the surface roughness of the polishing surface, so that the polishing speed can be significantly increased. As a result, it has become possible to manufacture a high-quality optical disk master that is highly reliable and always constant.

[Brief description of drawings]

FIG. 1 is a block diagram showing a tape polishing apparatus for an optical disk master according to an embodiment of the present invention.

FIG. 2 is a side view and a front view of a contact roller unit of a tape polishing apparatus for an optical disk master according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a polishing tape portion of an optical disc master tape polishing device.

FIG. 4 is a diagram showing a relationship between a polishing position and a rotation speed of an optical disc master according to an embodiment of the present invention.

FIG. 5 is a view showing a thickness distribution of an optical disc master when the optical disc master tape polishing apparatus in one embodiment of the present invention is used for polishing.

FIG. 6 is a diagram showing a relationship between a polished state (surface roughness) of an optical disc master and a reflectance of the polished surface.

FIG. 7 is a diagram showing a polishing time and a polishing state (surface roughness) of an optical disc master.

FIG. 8 is a diagram showing a pressure of a contact roller controlled with respect to a reflectance of a polishing apparatus according to an embodiment of the present invention.

FIG. 9 is a diagram showing a polishing rate when a polishing method according to an embodiment of the present invention is used.

FIG. 10 is a sectional view showing a general method for manufacturing an optical disk master and an optical disk.

FIG. 11 is a process diagram showing a general method for manufacturing an optical disc master and an optical disc.

FIG. 12 is a block diagram of a conventional tape polishing apparatus for an optical disc master.

FIG. 13 is a diagram showing a relationship between a polishing time and a polishing amount when a conventional optical disk master tape polishing device is used.

FIG. 14 is a diagram showing a relationship between a polishing position of an optical disc master and a rotation number in a conventional polishing method.

FIG. 15 is a diagram showing a thickness distribution of an optical disc master after polishing in the case of polishing by a conventional polishing method.

[Explanation of symbols]

30 Optical disc master 31 Tape mounting reel 32 Tape winding reel 33 Tape feeding roller 34 Tape winding roller 35 Abrasive tape section 36 Tape fixing base 37 Feed screw 38 Feed motor 39 Abrasive tape feeding section 40 Rotary table 41 Rotation Motor 42 rotation control device 43 rotation part 44 position detection sensor 45 position detection device 46 position detection part 47 contact roller unit 48 air control device 49 polishing head part 50 laser 51 light receiving sensor 52 reflected light measurement part 53 reflected light quantity measuring instrument 54 Reflected Light Amount Setting Device 55 Comparator 56 Reflected Light Comparison Unit 57 Contact Roller 58 Roller Fixing Stand 59 Air Cylinder 60 Air Supply Cylinder 61 Tape Winding Reel Motor 62 Tape Winding Roller Motor

Claims (4)

[Claims] 1. A polishing tape portion for feeding a polishing tape in a tape polishing apparatus for an optical disk master, a polishing head portion capable of changing pressure applied to the optical disk master according to a polishing state, a polishing tape portion and a polishing head portion. A fixed base for attaching the fixed base, a polishing tape feed unit for moving the fixed base, a position detection unit for detecting the polishing position, and an optical disk master to be polished for rotating at a rotational speed according to the polishing position. The rotating part, the reflected light measuring part for emitting light to the polished surface of the optical disc master and measuring the reflected light amount, the preset reflected light amount (or reflectance) and the measured reflected light amount (or reflectance) An optical disk master tape polishing apparatus comprising: a reflected light comparison unit for comparing and controlling the polishing time accordingly. 2. The polishing is performed by detecting the polishing position of the optical disc master, and rotating the optical disc master at a rotation speed corresponding to the polishing position of the optical disc master by the detected value, or by controlling the feed rate of the polishing tape. A method for polishing an optical disk master, wherein polishing is performed while controlling the relative speed between the tape and the polishing surface of the optical disk master to be always a constant speed. 3. A polishing surface of an optical disc master is irradiated with light such as a laser, the reflected light is measured, and the reflected light is pressed against the optical disc master to determine the friction coefficient between the polishing surface and the polishing tape. A method for polishing an optical disk master, wherein the pressure of the polishing tape is changed to perform polishing. 4. A polishing surface is finished by irradiating light such as a laser on the polishing surface of an optical disk master, measuring the reflected light, and finishing polishing when the amount of reflected light is equal to or exceeds a preset value. The method for polishing an optical disk master is characterized in that the polishing time is controlled according to the surface roughness.