JPH0765385A - Laser recording device - Google Patents

Abstract

PURPOSE:To provide a device capable of manufacturing an optical master disk of a high density by setting a laser beam on an arbitrary position out of the center of rotation so that the center of rotation does not exist on the moving locus of the laser beam in a laser recording device for manufacturing the optical master disk. CONSTITUTION:A laser beam 7 is set on the position of a distance L so that it does not pass through the center of rotation and the laser beam 7 is moved in the direction of arrow X so as to obtain a prescribed pitch Tp. At this time, the pitch Tp is made by geometrically compressing a distance T1, a pitch error component contained in the distance T1 is also relatively compressed, since the fine feed beyond the resolution of a laser measuring device 14 is performed, a master disk of a high density having a narrower pitch than before 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 laser recording device for a master of an optical disk using a laser.

[0002]

2. Description of the Related Art In recent years, optical discs are required to be miniaturized and have a large capacity as information recording media, and in order to realize them, development of a laser recording device for manufacturing a high-density disc master is being promoted. .

A conventional laser recording apparatus for manufacturing a disk master will be described with reference to a technique described in Japanese Patent Publication No. 57-74843 (title of the invention: optical information recording board and recording apparatus therefor).

FIG. 4 is a view for explaining a conventional optical information recording board and its recording device. In particular, FIG. 7A is a plan view in which a part of the optical information recording disk is broken, and FIG. 8B is a schematic sectional view taken along the line BB in FIG. It is a figure.

In the figure, a thin metal film 42 is formed on a glass substrate 41 to form an optical information recording master 43. At the center of this optical information recording master 43,
A hole is formed to push the rotation shaft of the motor 44 of the rotation driving means. An optical information recording device for optically recording information is arranged at a position above the optical information recording board 43. The optical information recording device includes an optical system 45 for generating the laser beam 7, a condenser lens 46 for converging the laser beam 7, and a feeding mechanism 47.

The case where the optical information recording device optically records information will be described below. The optical information recording board 43 is rotated by a motor 44 in the arrow Y direction around the rotation axis. On the other hand, the optical system 45 is moved in the arrow X direction by the feeding mechanism 47 on the optical information recording master 43.

At this time, the feeding mechanism 47 increases the recording density of the optical information recording board 43 in order to increase the recording density.
The optical system 45 is moved in the direction of the arrow Y at a pitch of a minute interval for each rotation of.

At the same time, the optical system 45 generates the laser beam 7 which changes in intensity depending on the recording signal. The laser beam 7 is focused on the metal film 42 by the condenser lens 46 and irradiates the metal film 42.

As a result, a part of the metal film 42 is
The pit 48 is formed. By repeating the recording of this information, the pits 48 are spirally recorded on the optical information recording board 43.

[0010]

However, the above conventional structure has the following problems. The first issue is
The pitch precision of the minute intervals depends on the feed precision of the feed mechanism 47 for feeding the optical system 45 and the rotation precision of the motor 44 that rotates the optical information recording board 43, and is determined from the relative relation of each precision. Nothing more than pitch accuracy can be achieved.

The condenser lens 46 operates in the arrow Z direction with respect to the optical information recording disc 43 to focus the laser beam 7 on the optical information recording master disc 43. The movement in the Z direction includes a variation in the X direction of the arrow, and this variation causes a pitch error.

Particularly in recent years, the feed mechanism 47 is composed of an air slider, a linear motor, a laser length measuring device, etc.
The pitch error was about ± 0.04 μm, which was the limit for high density.

The second problem is that the airflow generated by the rotation of the turntable 2 is generated by the optical system 45 and the feed mechanism 4.
It acts directly on 7, which causes disturbance and makes feed control unstable. The instability of the feed control due to this disturbance lowers the feed accuracy, and thus the optical information recording board 43.
This has affected the pitch accuracy of the pits 48 formed above.

Therefore, an object of the present invention is to provide a laser recording apparatus which can solve such conventional problems.

[0015]

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems includes a turntable for attracting a disk master, a spindle motor for rotating the turntable,
A rotation drive unit for driving a spindle motor, an optical head unit for condensing a laser beam emitted from a laser light source as a light source for exposing the disc master onto the disc master, and an optical head unit are mounted and sent. A laser recording device comprising: a slider for driving a linear motor attached to the slider; a feed drive unit for driving a linear motor attached to the slider; and a control unit for issuing a command to the rotation drive unit and the feed drive unit. The laser beam is set at an arbitrary position deviated from the rotation center so that the rotation center does not exist on the movement trajectory of the beam.

Either the feed speed of the slider or the rotation speed of the spindle motor is corrected in accordance with the distance from the rotation center to the laser beam position so that the distance between adjacent pits or grooves is constant, and An arithmetic unit for correction is provided.

Further, a curved windshield plate is provided between the turntable and the slider so that the airflow generated by the rotation of the turntable does not directly act on the slider.
The surface of the windshield has a structure in which a groove for changing the direction of the air flow is provided.

[0018]

[Operation] With this configuration, the turntable has one pitch
Since the value is smaller than the moving amount of the laser beam when it is rotated, it is possible to perform minute feeding exceeding the resolution of the laser length measuring device. In addition, by suppressing the action of the air flow generated when the turntable rotates on the optical system and the feed mechanism with the windshield,
The pitch accuracy can be improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of a laser recording apparatus showing an embodiment of the present invention, FIGS. 2 (a) and 2 (b) are views showing a laser beam arrangement on a disk master 1, and FIG. 3 is a shape of a windshield. FIG.

In FIG. 1, the laser recording apparatus of the present invention is
A turntable 2 for adsorbing a disk master 1 having a photoresist of 0.1 μm formed on a glass substrate, a spindle motor 3 for rotating the disk master 1, a rotation drive unit 4 for driving the same, and a rotational speed are detected. Optical encoder 10 (resolution 2000 pulses / rotation), and an optical head unit 10 including optical elements such as a reflecting mirror 8 and a lens 9 for focusing the laser beam 7 generated from the laser light source 6 on the disk master 1. A slider 11 for arranging the optical head unit 10 above the master disc 1, a linear motor 12 for moving the laser beam 7 on the master disc 1, and a feed drive unit 13 for driving the linear motor 12.
A laser length measuring device 14 (resolution 0.01 μm / pulse) that outputs a pulse corresponding to the moving speed of the laser beam 7,
It is composed of a rotation drive unit 4 and a control unit 15 for outputting a command to the feed drive unit 13.

Further, the control unit 15 includes a counter 16 for counting the pulses from the laser length measuring device 14, and an arithmetic unit 17 for calculating the position of the laser beam 7 from the count value and correcting the feed speed or the rotation speed. , A controller 18 for giving a command to the calculator 17, and a condition input device 19 for setting recording conditions.

Next, referring to FIGS. 2A and 2B, in the case of recording a video signal with a laser recording apparatus at a radius T of 50 mm from the disk master 1 in the direction of arrow X with a pitch Tp of 1.0 μm and a rotation speed of 1800 rpm. Will be described.

The disk master 1 attracted to the turntable 2 is rotated by the spindle motor 3 in the direction of arrow Y about the rotation axis.

On the other hand, the optical head portion 10 arranged on the upper part of the disk master 1 is moved in the arrow X direction by the linear motor 12.

At this time, the laser beam 7 radiated from the optical head unit 10 onto the master disk 1 is set in advance at a position moved by a distance L from the center of rotation so that the center of rotation does not exist in the direction of arrow X. In this laser recording, the distance L
Was set to 40 mm. The control unit 15 sets the distance L to 4 so that recording can be performed from a radius of 50 mm before starting recording.
The position of the laser beam 7 is calculated from 0 mm and the radius of 50 mm and moved to that position in advance.

Under these setting conditions, 30 points from point C to point A
The position of mm is the position of the laser beam 7, and by performing this distance correction, recording can be started from the position of 50 mm radius on the master disc 1.

Recording is performed by rotating the disk master 1 at a rotation speed of 1800 rpm and moving the slider 11 in the arrow X direction. The moving speed of the slider 11 at this time is the distance T1 from the point A of the laser beam 7 position to the point B of one rotation.
Is a speed conversion, and the distance T1 is a distance from the rotation center to the point A and a distance from the rotation center to B with the distance L as a constant.
Geometrically determined from the distance to the point.

That is, the point A has a distance of 50 mm from the center of rotation, and the point B has a distance of 5 mm from the center of rotation when it makes one rotation.
The distance T1 is a distance obtained by adding 1 μm of the pitch Tp to 0 mm, and the distance T1 from the point A to the point B at this time is about 1.7 μm, which is 51 μm / sec when converted into a velocity. In this way, the pitch Tp has a value obtained by reducing the distance T1 by about 40%, so that the amount of fluctuation in the direction of the arrow X that occurs when the lens 9 moves in the direction of the arrow Z is compressed, and the laser length measuring device 14 is used. The laser beam 7 can be minutely fed in the radial direction of the disk master 1 with a resolution of 0.01 μm or more.

Since the pitch Tp relatively changes as the slider 11 moves at a constant speed in the direction of the arrow X, the moving speed of the slider 11 is periodically corrected so that the pitch Tp becomes constant. To do.

To correct the moving speed, the counter 16 counts the pulses output from the laser length-measuring device 14 corresponding to the moving speed, and the count value is periodically read by the computing unit 17, and the total value is calculated. The optimum moving speed is calculated from the numerical value and is output to the feed drive unit 13 as a speed command signal.

Further, when the optical head unit 10 is arranged above the disk master 1 and the disk master 1 is rotated at 1800 rpm, an air flow with a wind speed of about 5 to 10 m / sec is generated.
This air flow becomes a turbulent state in the space between the slider 11, the disk master 1 and the optical head unit 10, which is one of the factors that make the optical system and the feed control system unstable and reduce the accuracy of the pitch Tp. .

Therefore, a windshield plate 30 is provided between the disk master 1 and the slider 11 so that the air flow does not directly act on the slider 11. The windshield plate 30 has a curved shape and is provided with a groove 31 on the surface thereof so that the airflow directly acting on the windshield plate 30 flows along the curve to thereby arrange the optical head portion above the master disc 1. The effect on 10 was suppressed. Therefore, the conventional pitch error ± 0.0
It was possible to reduce 4 μm to ± 0.02 μm.

In the present invention, the slider moving speed is corrected in order to keep the pitch Tp constant as one embodiment, but the same effect can be obtained by correcting one rotating speed.

[0035]

As described above, the laser recording apparatus of the present invention sets the laser beam at an arbitrary position deviated from the rotation center so that the rotation center does not exist on the movement trajectory of the laser beam. It is possible to compress the pitch error component of the optical head part and to perform minute feeding exceeding the resolution of the laser length measuring device, and it is possible to easily realize a high-density disc master with a narrower pitch than ever before.

[Brief description of drawings]

FIG. 1 is a block diagram of a laser recording apparatus according to an embodiment of the present invention.

FIG. 2 is a laser beam arrangement diagram on a disk master in the apparatus of the embodiment.

FIG. 3 is a perspective view of a windshield plate in the apparatus of the embodiment.

FIG. 4 is a block diagram of a conventional information recording master and its laser recording device.

[Explanation of symbols]

 1 Disc Master 2 Turntable 3 Spindle Motor 4 Rotation Drive Device 5 Encoder 6 Laser Light Source 7 Laser Beam 8 Reflection Mirror 9 Lens 10 Optical Head 11 Slider 12 Linear Motor 13 Feed Drive Device 14 Laser Length Measuring Device 15 Control Device 16 Counter 17 Calculator 18 Control unit 19 Condition input unit 30 Windshield 31 Groove 41 Glass plate 42 Metal film 43 Optical information recording board 44 Motor 45 Optical system 46 Condenser lens 47 Feed mechanism 48 Pit

Claims (5)

[Claims] 1. A turntable for adsorbing a disk master, a spindle motor for rotating the turntable, a rotation drive unit for driving the spindle motor, and a laser light source as a light source for exposing the disk master. An optical head unit for condensing a laser beam on the disk master, a slider for mounting and sending the optical head unit, and a feed drive unit for driving a linear motor attached to the slider, A laser recording device comprising a control unit for issuing a command to the rotation drive unit and the feed drive unit, wherein an arbitrary position deviated from the rotation center so that a rotation center does not exist on a movement trajectory of the laser beam. A laser recording apparatus, wherein the laser beam is set at a position. 2. A slider feed speed or a spindle motor rotation speed corresponding to the distance from the rotation center to the laser beam position so that the distance between adjacent pits or grooves on the disk master is constant. The laser recording apparatus according to claim 1, wherein one of the corrections is made. 3. A slider feed speed or a spindle motor rotation speed corresponding to the distance from the rotation center to the laser beam position so that the distance between adjacent pits or grooves on the disk master is constant. The laser recording apparatus according to claim 1, further comprising a computing unit that corrects one of them. 4. The laser recording apparatus according to claim 3, wherein the distance from the center of rotation to an arbitrary set position of the laser beam is set in the arithmetic unit in advance before recording is started. 5. A curved windshield plate is provided between the turntable and the slider so that an air flow generated by the rotation of the turntable does not directly act on the slider, and a curved windshield plate is provided on the surface of the windshield plate. 2. The laser recording device according to claim 1, further comprising a groove for changing the direction of the air flow.