JPH10320844A - Centering device of glass master disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the centering device of the glass master disk capable of rapidly and high precisely centering and dealing with the glass master disks having various kinds of diameter without rotating a turntable with a simple and inexpensive constitution. SOLUTION: This device is provided with at least three guide arms 8 arranged on concentric circles and moreover at equal angle intervals with respect to the rotation center of the turntable 2, the regulating member 5 for centering installed to each guide arm 8, the pressure plate 6 operating the guide arm 8 and the driving means driving the pressure plate up and down. The guide arm 8 rockingly rotated by the ascending of the pressure plate 6 and brought into contact with the outer periphery of the glass original master disk placed on the turntable 2 while reducing the diameter of the virtual circumscribed circle formed with each regulating member 5 for centering making the rotation center of the turntable 2 the center by simultaneously transferring these regulating members 5, whereby the center of the glass original master disk is set to the center of the turntable 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus for a glass master used in the manufacture of an optical disc, and a glass for centering the glass master so that the center of the glass master coincides with the rotation center of a turntable of the exposure apparatus. The present invention relates to a centering device for a master, but can also be used as a positioning device for a circular work.

[0002]

2. Description of the Related Art In a glass master disk apparatus for an optical disk,
If the center of the glass master serving as the master of the optical disc is deviated from the rotation center of the turntable of the exposure apparatus, an unbalanced centrifugal force due to eccentricity occurs during rotational recording on the glass master, that is, during rotation exposure. Vibration occurs, and as a result, the recording accuracy such as the track pitch recorded on the glass master is reduced. Furthermore, with the recent increase in the density of optical disks and the increase in the number of supplied optical disks, vibration due to this eccentricity has become a bottleneck in increasing the rotational recording speed.

For this reason, as a method of minimizing the eccentricity, conventionally, a center hole of an outer cylinder having a concentric circle is provided at the center of a glass master, and a center pin is provided on a turntable. There is a method of fitting and centering the hole. In this method, high precision processing is required for each of the center hole and the center pin, and the glass master becomes expensive. Further, the provision of the center hole in the glass master has a large effect on the subsequent process, and the problem due to the center hole is likely to occur. Therefore, a glass master with a center hole is not actually used.

[0004] Thus, at present, the center of rotation of the turntable and the center of the outer cylinder (theoretically, the center of gravity of the glass master) are made to coincide with each other as reliably as possible by the following method. The first method is that an operator mounting a glass master on a turntable sets a displacement meter such as an electric micrometer on the outer cylindrical end face of the master, and rotates the glass master on the turntable together with the turntable. , So that the eccentricity is minimized or within the allowable range,
This is for fine adjustment of the position of the glass master. A second method is to mount a glass master on a turntable and use a jig or the like so that the amount of eccentricity of the glass master with respect to the turntable falls within a predetermined allowable range, and the turntable is rotated at a predetermined rotation speed. Using a balance tester that detects the magnitude and direction of vibration caused by eccentricity, detects imbalance of the glass master and adds a balancer, or adjusts the position of the glass master Things.

[0005]

Both of the above two methods require time for work and require skilled workers. In addition, when a worker is interposed, dust is generated by a person, causing dust to adhere to the recording surface of the glass master disc, causing a problem such as a defect in a recorded signal recorded. In addition, in the second method, detection of acceleration used for measuring vibration generally has lower resolution than detection of displacement, so that an expensive detector is required to obtain the same resolution as displacement. There is a problem. For this reason, the following methods have already been disclosed.

First, the above-mentioned first method is automated to eliminate the intervention of an operator.
6, JP-A-1-210240, JP-A-1-210240
217760 and the like. However, these methods correct the amount of eccentricity by rotating the turntable at a relatively low speed, and confirm it. The time required for centering is relatively long, and the measuring unit, the driving unit, In addition, since these control units and the like are required, there is a problem that a complicated and expensive device is required for performing high-accuracy centering.

Next, there is a method using a scroll-type three-jaw chuck mechanism as represented in Japanese Patent Application Laid-Open No. 5-28541. In this method, the centering is completed instantaneously by simultaneously restricting the position and orientation of the glass master from at least three directions without rotating the turntable. Furthermore, since a displacement and acceleration measurement unit is not required, the configuration is simpler than in the above-described method.

However, in the case of this method, in order to perform high-precision centering, since the accuracy of each member has a one-to-one correspondence with the amount of eccentricity, each of the at least three or more adjustment members is provided. The same high accuracy is required for the guide groove, and thus the entire device is required to have high processing accuracy and the same assembling accuracy, thereby increasing the cost. is there.

Further, Japanese Patent Application Laid-Open No. 7-240037 discloses that at least three or more adjusting members are connected by link arms in consideration of the relationship between the amount of eccentricity and the accuracy of the adjusting member and the members constituting the adjusting member. A method is disclosed in which the relationship between the amount of eccentricity and the processing accuracy is reduced by applying this principle. However, in the case of this method, in power transmission in the connecting rod, errors due to elastic strain of the connecting rod are accumulated, and in fact, when the power balance of each adjusting member is broken and the glass master is centered, the power is released in a direction in which the power is released. The glass master moves. This phenomenon occurs particularly when the diameter of the glass master is changed. For this reason, this device is required for each diameter of the glass master,
As a result, there is a problem that the cost is increased.

The present invention has been made in view of the above circumstances, and has a simple and low-cost structure, which enables quick and high-precision centering without rotating a turntable. It is an object of the present invention to provide a centering device for a glass master disk that can handle a glass master disk.

[0011]

According to a first aspect of the present invention, there is provided an optical disk glass master exposure apparatus, wherein a turntable on which a glass master is placed for exposure, a base plate on which the turntable is arranged, and At least three guide arms arranged concentrically and equiangularly with respect to the rotation center of the turntable, a centering adjusting member attached to the guide arm, a pressure plate for operating the guide arm, and the pressure plate The guide arm is pivotally rotated by the driving of the pressure plate, and the imaginary circumscribed circle formed by each centering adjustment member around the rotation center of the turntable is provided. Adjust the diameter of each centering adjustment member While reducing the diameter of the imaginary circumscribed circle by moving simultaneously, in which each of said centering contact member is characterized by contacting the outer circumference of the glass master disk placed on the turntable.

According to a second aspect of the present invention, in the first aspect of the invention, each of the centering adjustment members has an inner and outer ring,
Further, the outer ring is formed of a rotatable member.

According to a third aspect of the present invention, in the first or second aspect of the present invention, a linear driving device such as an air cylinder is used as a driving means for driving the pressure plate up and down, and an elastic member such as a spring is used. By attaching a power limiter utilizing deformation, power above a predetermined level is not transmitted to the guide arm or the glass master.

According to a fourth aspect of the present invention, there is provided the first or second or third aspect.
In the invention, the guide arm, the centering adjustment members and the pressure plate are disposed on a unit plate separate from the base plate, and are formed by the rotation center of the turntable and the centering adjustment members. A position adjusting means for adjusting the position of the unit base with the center of the virtual circumscribed circle is provided, and the position of the unit base can be adjusted and fixed by the position adjusting means.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

(Description of Configuration) FIG. 1 is a schematic plan view of an essential part for explaining an embodiment of a centering device according to the present invention, FIG. 2 is a schematic sectional view of a pressure plate portion, and FIG. In the figure, 1 is a glass master for exposure recording, 2 is a turntable on which the glass master for exposure recording 1 is mounted, 3 is a spindle for rotating the turntable 2, and 4 is a fixed spindle 3. Spindle base 4. The turntable 2 has a number of grooves 2a and 2b formed in an annular shape on the glass master mounting surface in order to hold the glass master 1 mounted on the turntable 2. The grooves 2a and 2b are formed with a conduit connected to a vacuum source (not shown) and a control valve through the spindle 3. By operating the valves or the vacuum source, the grooves 2a and 2b become vacuum pools and the glass master 1 Has a structure in which it is vacuum-adsorbed and held on the turntable 2.

Reference numeral 5 denotes an adjusting member for directly contacting the glass master 1 and centering and moving the glass master 1. The adjusting member 5 is preferably a member having an inner and outer ring and a rotatable outer ring. It is desirable to be configured (for example, using a bearing or a roller follower). This is because, when the glass master 1 is centered, the centering is performed while the outer cylindrical portion of the glass master 1 is pressed by the adjusting member 5, so that friction occurs between the adjusting member 5 and the glass master 1. If the frictional resistance is large, not only does it adversely affect centering, but if it is severe, it damages the glass master. To avoid this, use the above-described bearings and roller followers, and use the glass master 1
Is to minimize the frictional resistance due to the contact with the adjustment member 5.

As shown in FIGS. 3 and 4, the adjusting member 5 has one end thereof in contact with the pressure plate 6, and is attached to a guide arm 8 which can swing about a rotation shaft 7. The guide arm 8 is attached to the support 9 (formed so as not to hinder the swing operation of the guide arm 8) at a certain angle with respect to the pressure plate 6. One end of the guide arm 8 is always in contact with the pressure plate 6 by an elastic member such as a spring (not shown). Assuming that a series of components from the adjusting member 5 to the support 9 is referred to as an adjusting unit 10, the adjusting unit 10 has at least three or more (three in the illustrated example) with respect to the rotation center of the turntable 2. Unit base 1 on concentric circles and at equal angular intervals
1.

The pressure plate 6 has a power limiter 13 using a spring 12 and an air cylinder 1 connected through the power limiter 13.
4, and a plurality of linear guides 15 for obtaining accurate vertical movement.

(Explanation of Operation) A glass master 1 for exposure recording, which is a master of an optical disk, is mounted on a turntable 2 manually or by using an automatic transfer means such as a transfer machine (not shown). At this time, it is desirable to keep the pressure plate 6 at the lower limit. That is, the guide arms 8 of the three adjustment units 10 that are in contact with the pressure plate 6 are at the positions of the top dead center of the oscillating motion, that is, the three adjustment members 5 attached to the guide arms 8 are formed. The diameter of the virtual circumscribed circle becomes the maximum diameter, and the glass master 1
Facilitates mounting.

Next, in order to center the center of the outer cylinder of the mounted glass master 1 on the center of rotation of the turntable 2, first, the air cylinder 14 is driven and the pressure plate 6 is raised. At this time, the air cylinder 1
It is desirable to prevent the sudden vertical movement by adjusting the inflow air amount of No. 4 with a speed controller or the like. The ascending pressure plate 6 simultaneously lifts one end of the guide arm 8 of each adjusting unit 10 in contact, whereby each guide arm 8 starts swinging motion at the same time.

As shown in FIG. 5, the trajectory of the adjusting member 5 at the tip of the oscillating guide arm 8 is represented by α with respect to the XY plane.
Draw a circular orbit on the X'-Y 'plane inclined at an angle. this is,
If each adjustment unit is compared to a baseball pitcher,
This is the same as the trajectory of the arm when the player throws the ball at a three quarter throw (between over throw and side throw) toward the rotation center of the turntable 2. As described above, the oscillating movement of the adjusting members 5 simultaneously causes the virtual circumscribed circle formed by these three adjusting members 5 to gradually decrease in diameter as shown in FIG. Then, the glass master 1 is pressed and moved until the adjusting members 5 uniformly contact the outer cylindrical portion of the glass master 1. When each adjusting member 5 uniformly contacts the glass master 1, the virtual circumscribed circle and the center of the outer circumferential circle of the glass master 1 coincide. That is, the centering of the rotation center of the turntable 2 and the center of the glass master 1 is completed.

However, even after the centering, the pressure plate 6 tends to rise to the stroke end of the air cylinder 14, so that the guide arm 8
May be further swung, and the guide arm 8 and the glass master 1 may be damaged. Therefore, the spring 12
By disposing the power limiter means 13 using the pressure plate between the pressure plate 6 and the air cylinder 14,
The pressure plate 6 is prevented from rising more than the stroke required for centering.

For example, it is possible to consider using a sensor for detecting that the three adjusting members 5 have come into contact with the glass master 1 or a strain gauge for detecting an increase in the stress of the guide arm. Therefore, a control unit is required, and the apparatus becomes expensive, so that the object of the present invention cannot be achieved.

The centered glass master 1 is vacuum-adsorbed on the turntable 2 by operating a vacuum source or a control valve (not shown), and is positioned on the turntable 2. After positioning the glass master 1, the pressure plate 6 is lowered in the reverse order of the centering, and the adjusting member 5 is detached from the outer cylindrical portion of the glass master 1 to complete a series of centering operations.

Further, the position of the unit base 11 and the spindle base 4 can be adjusted by attaching a position adjusting means (for example, an XY axis stage) (not shown) to the unit base 11. For example, the work can be easily performed without any skill such as adjustment at the time of assembling the device or retrofitting the centering device to the spindle.

[0026]

As is apparent from the above description, according to the present invention, the centering can be performed quickly and accurately with a simple and low-cost structure without rotating the turntable, and various types of diameters can be obtained. And a centering device for a glass master disk that can correspond to the above glass master disk.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a main part of a glass master disk centering device according to the present invention.

FIG. 2 is a schematic sectional view taken along the line II-II in FIG.

FIG. 3 is a schematic configuration diagram of an adjustment unit.

FIG. 4 is a schematic view of a side view (FIG. 4A) and a front view (FIG. 4B) of the adjustment unit.

FIG. 5 is a diagram illustrating a trajectory of the adjustment member when the guide arm swings and rotates.

FIG. 6 is a diagram showing a change of a virtual circumscribed circle due to swinging rotation of a guide arm.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass master, 2 ... Turntable, 3 ... Spindle, 4 ... Spindle base, 5 ... Adjustment member, 6 ... Pressure plate, 7 ... Rotating shaft, 8 ... Guide arm, 9 ...
Prop, 10 adjustment unit, 11 unit base, 1
2 ... spring, 13 ... power limiter means, 14 ...
Air cylinder, 15 ... Linear guide.

Claims (4)

[Claims] 1. A turntable for placing a glass master, a base plate on which the turntable is arranged, and at least three turntables arranged on the base plate concentrically and equiangularly with respect to the rotation center of the turntable. A guide arm, a centering adjustment member attached to the guide arm, a pressure plate for operating the guide arm, and driving means for driving the pressure plate up and down, wherein the guide arm is Oscillating rotation is caused by the vertical movement of the plate, and by the oscillating rotation, the diameter of a virtual circumscribed circle formed by each of the centering adjustment members is changed around the rotation center of the turntable. On the outer periphery of the glass master placed on the turntable A centering device for a glass master, which is in contact with the glass master. 2. The centering device for a glass master according to claim 1, wherein each of the centering adjusting members is formed of a member having an inner and outer ring and a rotatable outer ring. 3. The glass master according to claim 1, further comprising a power limiter in a driving unit for driving the pressure plate up and down, so that power of a predetermined value or more is not transmitted to the glass master. Centering equipment for glass masters. 4. Each of the guide arms, each of the centering adjusting members, and the pressure plate are provided on a unit base different from the base plate on the base plate, and the rotation center of the turntable and the centering are provided. A position adjusting means for adjusting the position of a center of a virtual circumscribed circle formed by the adjusting member, wherein the position of the unit base can be adjusted and fixed by the position adjusting means.
A glass-based centering device as described.