JPH03108142A - Optical master disk working device - Google Patents

Abstract

PURPOSE:To increase frictional resistance in a thrust direction and to suppress aberration in the pitch direction of an arm by setting thrust rigidity as the fulcrum of an anti-friction bearing at 40gf/mum or more. CONSTITUTION:An air spindle 11 with the thrust rigidity of at least >=40gf/mum is used as the fulcrum of constant-pressure notch constitution comprised of a voice coil 15 and the arm 12. And a rotary table 17 is rotated at constant rotating speed as pressing a diamond tool on a work material fixed on the table with a constant normal load. Simultaneously, the diamond tool 14 is moved with an air slider 16 at constant speed, and a pre-group can be formed in spiral shape. Then, the frictional resistance of the anti-friction bearing can be increased by the mass of the arm 12, the tool 14, and a balance weight, and the aberration of the arm 12 in the pitch direction due to the fluctuation of cutting resistance can be suppressed. At such a case, the rigidity only in the thrust and radial directions is increased by using an air bearing, which prevents rotating frictional resistance increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical disk master processing apparatus that processes an optical disk master with pregroups by forming pregroups, which are fine grooves, by a constant pressure cutting method.

[Conventional technology]

Conventionally, when forming micro-grooves (pre-groups) on the surface of a disc-shaped workpiece using low-pressure cutting methods, the movement of the tool is restricted in a plane perpendicular to the direction of cut, but it is allowed to move freely in the direction of cut. An optical disk AM Karoe device is required that has a constant pressure cutting mechanism consisting of a tool rest, a tool, and a load adjustment device that applies a vertical load to the tool.

FIGS. 4(a) and 4(b) are a top view and a front view of a constant pressure cutting mechanism of an optical disk master Kaloe device, which shows an example of the conventional art. As shown in the figure, this constant pressure cutting mechanism uses a rolling bearing 23 and a rotating shaft 22 as a fulcrum, and an arm 12 and an arm 1 that are rotatable around the rolling bearing 23.
The diamond tool 1 is attached to the tip of the diamond tool 1 via the tool holder 13.
4 is fixed, and a load adjustment mechanism that attaches a balance weight 24 to the other end of the arm 12 and applies a vertical load F to the diamond tool 14 using the lever principle. ing.

Further, when processing a pre-group of an optical disk, the shape is generally spiral, and the precision of the pitch is required to be at least ±0.05 μm or less.

[Problem to be solved by the invention]

However, in the above-mentioned conventional optical disk master processing device having a constant pressure cutting mechanism, the constant pressure cutting mechanism is
As shown in the figure, the diamond tool 14 can move freely in the cutting direction, but due to the submicron-order bearing clearance (play) between the rollers that constitute the rolling bearing 23 and the housing, the diamond tool 14 can move freely in the cutting direction. It was difficult to position with an accuracy of ±0.05 μm or less within a plane perpendicular to .

SUMMARY OF THE INVENTION An object of the present invention is to solve such conventional problems and provide an optical disk master processing apparatus that can form pull groups by a constant pressure cutting method with a pitch accuracy of at least 0.05 μm or less.

[Means to solve the problem]

The optical disk master force Loe device of the present invention has an arm rotatable around a fulcrum, a diamond tool attached to the tip of the arm, and uses the principle of leverage to position the diamond tool on a disk-shaped workpiece. In an optical disk master processing device that rotates a workpiece while pressing it with a pressing force and simultaneously feeds the diamond tool in the radial direction of the workpiece to form a pre-group in a spiral shape by a constant pressure cutting method, the fulcrum The thrust rigidity is at least 640 gf/μm or more, or the fulcrum is an air bearing, a hydraulic bearing, or a magnetic bearing.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

1(a) and 1(b) are a top view and a front view of an optical disk master processing apparatus showing an embodiment of the present invention, and FIG.
a) and (b) are a front view and a side view showing the diamond tool of FIG. 1, and FIG. 3 is a sectional view showing a portion of an optical disk master processed by the optical disk master processing apparatus of FIG. 1. As shown in FIGS. 1(a) and 1(b), this optical disk master processing device includes a rotary table 17 on which a workpiece is mounted and rotated, a diamond tool 13 attached to one end, and a load adjustment mechanism at the other end. an arm 12 that is in contact with a certain voice coil 15 and has a rotational fulcrum in the middle;
This arm is equipped with an air spindle 11 whose rotating shaft is fitted into the rotational fulcrum of the arm, and this air spindle 11,
It consists of an air slider 16 that sends the diamond tool 13 in the radial direction of the work piece.

Further, the fulcrum of the constant pressure cutting configuration consisting of the voice coil 15 and the arm 12 has a thrust rigidity of 4 kg f
/ μm (air pressure 6 kgf/cm 2 ). That is, the arm 12 is attached to the air spindle 11, the diamond tool 14 is fixed to the tip of the arm 12 via the tool holder 13,
A voice coil 15 for load adjustment was attached to the other end of the arm 12.

The processing of the pre-group is carried out by rotating the rotary table 17 at a constant rotation speed of 600 rpm while pressing the diamond fixing against the rigid material fixed on the rotary table 17 (air bearing) with a constant vertical load F = 2.2 gf. The test was carried out by moving the diamond tool 14 using the air slider 16 at a constant speed V=0.96 mm/min. Here, the pre-group is formed in a spiral shape,
The pitch was 1.6 μm.

Normally, by increasing the mass (inertial mass) of the arm, tool, and balance weight, it is possible to increase the frictional resistance of the rolling bearing in the thrust direction and the pitch direction, thereby suppressing positional deviation of the arm in the pitch direction due to fluctuations in cutting resistance. can do. However, at the same time, the rotational frictional resistance of the rolling bearing increases, and the resolution of the vertical load applied to the tool, that is, the resolution of the tool's depth of cut control amount, decreases, resulting in a decrease in group depth accuracy. Therefore, in order to improve pitch accuracy without reducing group depth accuracy, it is necessary to increase only the thrust rigidity of the bearing portion (fulcrum) without increasing the rotational frictional resistance of the bearing. When an air bearing, a hydraulic bearing, or a magnetic bearing is used as the fulcrum, the rigidity in the thrust direction and the radial direction can be increased without increasing rotational frictional resistance.

Therefore, the material to be stiffened is a polished glass disk 18 with a diameter of 130 mm, and copper 19 and gold 20 are each coated with 0.04
A material formed by sputtering to a thickness of μm (total o, 08 μm) was used. In addition, the diamond tool 14 is shown in FIG.
As shown in a) and (b), each of the two escapes (γ1=0
degree, γ2=0.3 degree), and rake degree α=
Groups were formed by setting the angle to 0 degrees.

Furthermore, the depth of cut of the diamond tool 14 is controlled by using the glass disk 18 as a stopper layer that determines the depth of extinction, which is equal to the sum of the film thicknesses of copper 19 and gold 20, as shown in FIG. A pre-group (width 0.8 μm) with a depth of 0.08 μm was formed. When the pitch accuracy of the formed pre-group was measured with a distance measuring device using an electron microscope, the pitch was 1.6 ± 0.03 μm.
It was confirmed that the required pitch accuracy of ±0.05 μm could be achieved.

From the above, in order to achieve a pre-group pitch accuracy of ±0.05 μm, it is necessary to at least adjust the rotational fulcrum part so that the pitch variation is 0°05 μm or less for the maximum variation of cutting force in the pitch direction of 2 gf. It is necessary to use a fulcrum whose thrust rigidity (rigidity in the pitch direction) is 40 gf/μm or more.

In one embodiment of the present invention, an air bearing (air spindle 11) 9 was used as the fulcrum, but even if a hydraulic bearing or a magnetic bearing with a thrust rigidity of 40 gf/μm was used as the fulcrum, the pitch accuracy would be similarly improved. It was confirmed that Puri Group could be managed within ±0.05 μm.

〔Effect of the invention〕

As described above, according to the optical disk master processing apparatus of the present invention, the pitch accuracy is at least ±0.05 μm or less.
This has the effect of providing an optical disk master processing apparatus that can manufacture optical disk masters with high-precision pregroups.

Voice coil, 16...Air rider, 17...Rotary table, 18...Glass disk, one...
・Copper, 20...Gold, 21...Pri group, 22・
... Rotating shaft, 23... Rolling bearing, 24... Balance weight.

Claims (1)

[Claims] 1. An arm rotatable around a fulcrum is attached, a diamond tool is fixed to the tip of this arm, and the diamond tool is fixedly pressed against a disc-shaped workpiece using the principle of leverage. In an optical disk master processing device that rotates a workpiece while pressing it with pressure and simultaneously feeds the diamond tool in the radial direction of the workpiece to form a polygroove in a spiral shape by a constant pressure cutting method, the fulcrum is An optical disk master processing device characterized by having a thrust steel property of at least 40 gf/μm or more. 2. The optical disk master processing apparatus according to claim 1, wherein the fulcrum is one of an air bearing, a hydraulic bearing, or a magnetic bearing.