JPH07270705A - Hologram disk and positioning method therefor - Google Patents

Abstract

PURPOSE:To provide a hologram disk capable of adjusting eccentricity with high accuracy, and a positioning method therefor. CONSTITUTION:Plural hologram facets 12a to 12f for deflecting a light beam to perform scanning are arranged in the circumferential direction on the hologram disk 10, and aligning patterns 14a to 14f are formed on the outside thereof. The eccentricity is made minimum by adjusting so that the pitch of an enlarged image obtained by observing the aligning pattern or the number of fringes per unit length may be nearly constant to the rotation of the hologram disk 10, because the pitch of the patterns 14a to 14f in the radial direction is changed according to the radius. Thereafter, the hologram disk 10 is regularly fixed to a rotary shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram disk for scanning a light beam and a method for positioning the hologram disk.

[0002]

2. Description of the Related Art FIG. 12 shows the configuration when a hologram disk is used in an optical scanning device such as a laser printer. The hologram disk 101 is fixed to the rotation shaft 103 of the motor 102 and rotates. When the hologram disc 101 is irradiated with the laser beam 110 from the semiconductor laser 105, the laser beam 110 is diffracted by the hologram disc 101, and the diffracted beam 112 converges as a light spot 120 on the photosensitive drum 115. As the hologram disk 101 rotates, the light spot 120 scans on the photosensitive drum 115. Here, as shown in FIG. 13, the rotation center of the hologram disk 101 is the rotation shaft 103 of the motor 102.
When the eccentricity is generated with respect to the rotation center of, the incident position of the laser light 110 on the hologram disk 101 is relatively displaced depending on the amount of the eccentricity. Hologram disc 10
The hologram formed in No. 1 has a different spatial frequency depending on the location. Therefore, when the incident position of the laser light 110 is relatively displaced, the diffraction angle is changed due to the difference in spatial frequency, and the emitting direction of the diffracted light 112 is periodically changed. This allows
Non-uniform scanning line spacing occurs in laser printers,
The quality of the printed image deteriorates.

In such a hologram disc 101, in order to reduce the eccentricity when the motor 102 is attached to the rotary shaft 103, a hologram pattern for deflecting the laser light of the hologram disc 101 is conventionally formed as shown in FIG. Hologram facet 121
The position adjusting hologram 123 was formed inside the. Here, the position adjusting hologram 123 is provided with a pinhole mask 133 on the central axis of the hologram disc 101 as shown in FIG.
Irradiate 1 as the reference light. At this time, the light passing through the pinhole 130 of the pinhole mask 133 becomes a spherical wave 132 which is an object wave. This parallel light 131 and spherical wave 1
The position adjusting hologram 123 is recorded by interference with 32. When performing the positioning, as shown in FIG. 14, a reproduction parallel light beam 12 having the same wavelength as that of the recording light beam and parallel to the rotation axis 103 is used.
5 is irradiated on the position adjusting hologram 123, and the diffracted light reproduces the point image 127 on the rotation center axis 103. And
The eccentricity is adjusted by rotating the hologram disk 101 to converge the locus of the point image 127 into one point.

[0004]

However, as shown in FIG.
If the position error of the pinhole 130 is recorded during recording of the position adjusting hologram 123 and the parallel light 131 during recording is tilted from the center axis of rotation, the image of the point image 127 becomes the center of rotation during alignment shown in FIG. If the point image 127 is reproduced at a position away from the axis 103 and the point image 127 is adjusted so as to be located on the rotation center axis 103, there is a problem that decentering occurs. Furthermore, if the reproduced parallel light 125 has an inclination from the rotation center axis 103 during alignment, the point image 127 is still present.
Image is reproduced at a position distant from the rotation center axis 103, and if the point image 127 is adjusted so as to be located on the rotation center axis, there is a problem that eccentricity and surface runout increase.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a hologram disc capable of highly accurately adjusting the eccentricity and a positioning method thereof.

[0006]

In order to achieve this object, a hologram disc of the present invention is a hologram disc in which a plurality of hologram facets for scanning a light beam are arranged, and a position at which a pitch varies depending on a radius. A matching pattern is formed. At this time, the radial pitch of the alignment pattern may monotonically increase or decrease. Further, the alignment pattern may be formed outside the hologram facet.

Further, in the hologram disc positioning method of the present invention, a step of observing an alignment pattern formed on a predetermined portion of the hologram disc, a step of positioning the hologram disc, and a step of positioning the hologram disc after the positioning are performed. Fixing to the rotary drive shaft. At this time, the pitch or the number of alignment patterns is detected in the observation step.

[0008]

In the hologram disc and its positioning method of the present invention having the above-mentioned structure, the alignment patterns formed on the hologram disc and having different pitches depending on the radius are observed, and at this time, the pitch or the number of the alignment patterns is detected. . The hologram disk is positioned so that the number of patterns per pitch or unit length becomes substantially the same at a plurality of predetermined observation positions on the hologram disk, and then fixed to the rotary shaft.

At this time, since the radial pitch of the alignment pattern monotonically increases or decreases, the eccentric direction can be easily detected. Further, by forming the alignment pattern on the outer side of the hologram facet, it is possible to arrange the exposure optical system of the alignment pattern at a position that does not interfere with the exposure optical system of the hologram facet.

[0010]

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

A hologram disk 10 to which the present invention is preferably applied has a plurality of hologram facets 12a, 12b, 12 for deflecting and scanning a light beam as shown in FIG.
c, 12d, 12e and 12f are arranged along the circumferential direction. Hologram patterns required for scanning and focusing laser light are formed on the hologram facets 12a to 12f in the form of surface irregularities. The alignment patterns 14a, 14b, 14c, 14d, 14e, 14
f is provided.

A method of manufacturing such a hologram disc 10 will be described with reference to FIG. First, as shown in FIG. 1A, a photoresist 22 is applied onto a substrate 21 such as glass by a spin coating method, and a He-Cd laser having a predetermined wavefront such as a spherical wave or a plane wave with a wavelength of 442 nm is used. The lights 25 and 26 are irradiated and interfered with each other to expose the hologram facet 12a. At this time, the exposure is performed through the mask 23 so that only the necessary portion 27 is exposed.

Similarly, as shown in FIG. 2B, the alignment pattern 14a is exposed to the portion 30 outside the exposed portion 27 of the hologram facet 12a through the mask 31. At this time, for example, the parallel light 32 is used as the reference light.
The light emitted from the cylindrical lens 34 is used as the object light 33, and the two patterns 32 and 33 are caused to interfere with each other to expose the alignment pattern. The pattern of the interference fringes produced by this is a linear lattice pattern with different pitches depending on the location. Further, this makes it possible to dispose the optical system that exposes the outer portion 30 at a position that does not interfere with the optical system that exposes the hologram facet 12a.

Next, the substrate 21 is moved to the central axis 36 at a predetermined angle.
Rotate around the
b and the alignment pattern 14b are exposed. Similarly, the hologram facets 12c, 12d, 12
e, 12f and the alignment patterns 14c, 14
Exposures d, 14e, and 14f are sequentially performed. Here, the optical system that exposes the hologram facets 12a to f and the optical system that exposes the alignment patterns 14a to f are fixed until the exposure of all the hologram facets 12a to f and the alignment patterns 14a to f is completed. For,
The hologram facets 12a to 12f and the alignment patterns 14a to 14f are formed such that their relative positions are fixed with respect to the same central axis 36. That is, the center of rotation of the hologram facets 12a to 12f and the center of rotation of the alignment patterns 14a to 14f always match. Therefore, by minimizing the eccentricity by using the alignment patterns 14a to 14f, the eccentricity is also minimized to the hologram facets 12a to 12f.

After exposure and development, hologram 22 forms hologram facets 12a-f and alignment patterns 14a-f by photoresist 22, as shown in FIG. Using this as the master disc, as shown in FIG.
After electroforming, a Ni film 38 is formed on the surface, and then the Ni electroformed film 38 is peeled from the master as shown in FIG. 2E, whereby a Ni stamper 38 having a hologram pattern formed on the surface is manufactured. . By using this stamper 38 as a part of the mold 40 and injecting a resin 41 as shown in FIG. 2F, injection molding is performed, whereby the hologram disk 10 as shown in FIG. As the resin used for injection molding, acrylic resin, polycarbonate resin, polyolefin resin or the like is used.

A method of positioning the hologram disk 10 according to this embodiment will be described with reference to FIG. First,
The hologram disk 10 is temporarily fixed to a rotation drive means, for example, a rotation shaft 43 of a motor 41. Then, the alignment pattern, for example, 14a formed on the hologram disk 10 is observed by an image magnifying means, for example, a microscope 45 and a magnified image detecting means, for example, a CCD camera 46.

FIG. 4 shows the appearance of the magnified image observed.
Since the alignment patterns 14a to 14f are in the shape of a linear lattice having different pitches depending on the location, the magnified image is shown in FIG.
As shown in (a). Here, when the hologram disk 10 is rotated, the alignment patterns 14a to 14f are also rotated, the enlarged image is also rotated as shown in FIG. 7B, and the pitch is also changed.

Here, for example, the hologram disk 10
If there is eccentricity when is temporarily fixed to the rotary shaft 43, the pitch changes at the lattice position corresponding to FIG. 7A, that is, the position where the stripes are in the vertical direction, and the pitch of FIG. Such a magnified image is observed. Here, the alignment patterns 14a to 14f have a radial pitch at a location,
That is, in the case where it is formed so as to monotonically increase or decrease depending on the radius, the eccentric direction can be determined by measuring the pitch of the magnified image or the number of stripes per unit length. That is, for example, assuming that the alignment patterns 14a to 14f are formed such that the pitch becomes narrower toward the outer peripheral side, as shown in FIG. 7C, if the pitch decreases, the position becomes inward, and conversely, FIG. It can be seen that as the pitch increases, it is eccentric to the outside, as shown in FIG.

Therefore, the position of the hologram disk 10 is adjusted by an eccentricity adjusting mechanism (not shown) so as to reduce such eccentricity, and the hologram disk 10 is rotated again to observe an enlarged image. Here, the eccentricity adjusting mechanism has moving means for moving the hologram disk 10 in parallel with the rotation drive shaft 43 in the hologram disk plane. As such moving means, a micrometer mechanism, a moving cylinder mechanism, a moving pin mechanism, a linear motor mechanism, etc. are used.

The eccentricity can be minimized by repeating the above steps so that the pitch of the magnified image becomes almost invariable with the rotation of the hologram disk 10. After that, the hologram disk 10 is permanently fixed to the rotation shaft 43. The fixing method is not particularly limited, but screwing, adhesion with an adhesive, for example, an ultraviolet curable resin or the like may be used.

Further, in the above-described embodiment, since it is necessary to measure only the pitch when the stripes of the enlarged image are in the vertical direction, it is not necessary to rotate the hologram disk 10 continuously, and for example, it is rotated stepwise. You may let me. In a magnified image, the number of stripes per pitch or unit length can be automatically measured by image processing, and the eccentricity adjustment mechanism is controlled by this measurement value to automatically position the hologram disk 10 for a short time and at a high position. Can be done with precision. For example, since the eccentric direction and the eccentric amount can be calculated by subtracting the measured number of stripes from the reference value,
A control value for controlling the eccentricity adjusting mechanism can be easily obtained.

Although one embodiment of the present invention has been described in detail above with reference to FIGS. 1 to 4, the present invention is not limited to the embodiment described in detail above, and within the scope of the invention. Various changes can be made.

In the above embodiment, the number of hologram facets was 6, but the number is not limited to this.
For example, it may be 2, 7, 8 or the like. Further, the position of the alignment pattern does not have to be formed over the entire outer circumference of the hologram facets 12a to 12f. For example, as shown in FIG.
a, 51b, 51c, 51d, 51e, 51f may be formed. At this time, as described in the previous embodiment,
The hologram disk 10 may be rotated stepwise during positioning.

Also, it is not necessary that the hologram facets 12a-f and the alignment patterns 14a-f be of the same number. For example, as shown in FIG.
It may be prepared every °. Also at this time, the exposure of all the hologram facets 12a to f and the alignment patterns 53a to d is completed in the optical system that exposes the hologram facets 12a to 12f and the optical system that exposes the alignment patterns 53a, 53b, 53c, and 53d. Since it is fixed up to, hologram facets 12a-12f
The alignment patterns 53a to 53d are formed such that their relative positions with respect to the same central axis are fixed. At this time, by comparing the magnified images of the facing alignment patterns 53a and 53c and 53b and 53d, the eccentricity can be efficiently adjusted in two orthogonal directions.

Also, the alignment pattern need not be provided outside the hologram facets. For example,
As shown in FIG. 7A, the hologram facets 12a ...
The alignment patterns 55a to 55f may be formed inside f. Further, as shown in FIG. 7B, the alignment pattern 57a is provided between the hologram facets 12a to 12f.
~ F may be formed. Thereby, the hologram disk 10 can be downsized.

The alignment pattern is not limited to the linear grid pattern. For example, if the pitch differs depending on the radial position, it may be curved like the enlarged image shown in FIG. Such a pattern can be formed by using a spherical lens or a pinhole instead of the cylindrical lens 34 in FIG.

The radial pitch of the alignment pattern does not necessarily have to monotonically increase or decrease, and a pattern as shown in FIG. 9 may be used. At this time, if the amount of eccentricity is relatively small, an enlarged image near 82 or 84 may be observed.

The size of the pitch of the alignment pattern in the radial direction is not particularly limited. The radial pitch is appropriately determined by the positioning accuracy of the hologram disk 10 and the magnification of the image magnifying means. For example, it is selected in the range of about 0.5 μm to 10 μm. Also, FIG.
The parallel light 32 does not need to be parallel to the rotation axis 36 during the exposure of (b). For example, the light may be obliquely incident on the rotating shaft 36 from the outer side. Thereby, the interference of the hologram facets 12a to 12f with the exposure optical system is further reduced, and the exposure optical system of the hologram facets 12a to 12f can be arranged more freely. The cylindrical lens 3
The position, inclination, etc. of No. 4 are not particularly limited, and there is no restriction on the rotary shaft 36 as in the conventional example. Therefore, the positional displacement of the alignment patterns 14a to 14f during exposure only changes the pitch of the alignment patterns 12a to 12f as a whole, and this does not adversely affect the positioning of the hologram disk 10. Highly accurate positioning is possible.

Further, it is not always necessary to rotate the hologram disk 10 when adjusting the eccentricity. For example, as shown in FIG. 10, the hologram disc 10 is rotated by simultaneously measuring a plurality of alignment patterns using a plurality of image magnifying means 74, 75, 76 and magnified image detecting means 77, 78, 79 and the like. Eccentricity adjustment can be performed without it. That is, the reference circle previously formed so that the eccentricity with respect to the rotary drive shaft 43 becomes substantially zero is provided with a plurality of image magnifying means 7.
4, 75, 76 and the magnified image detecting means 77, 78, 79 so that the reference circle is positioned at the center of the magnified image.
Each image magnifying means 74, 75, 76 and magnified image detecting means 77,
Adjust the positions of 78 and 79. As a result, the eccentricity can be minimized by adjusting the position of the hologram disc 10 so that the radial pitches of the magnified images observed by the magnified image detecting means are all the same.

Further, the rotary drive shaft for fixing the hologram disk does not need to be fixed or integrally formed with the rotary shaft of the motor. That is, as shown in FIG. 11A, after fixing the rotary drive shaft 43 to the hologram disc 10,
The rotary drive shaft 43 may be fixed to the rotary shaft 42 of the motor 41 as shown in FIG.

The hologram pattern of the hologram facets 12a to 12f is not particularly limited. For example, it may be a pattern obtained by the interference of two spherical waves or the interference of a spherical wave and a plane wave. Further, appropriate aberration may be added to the wavefront at the time of interference. Further, the light emitted from the computer generated hologram (CGH) may be interfered with each other.

Further, the method for producing the hologram is not limited to injection molding. For example, a so-called 2P method (photopolymerization method) may be used in which a sheet or substrate coated with a photopolymerization-curing resin is brought into close contact with a stamper to be cured by irradiation with ultraviolet rays to produce a duplicate.

[0033]

As is apparent from the above description, in the hologram disc and the positioning method thereof according to the present invention, the hologram disc is positioned by observing the alignment pattern formed on the hologram disc, and the eccentricity is reduced. Since it is fixed to the rotary drive shaft after adjustment so as to be the minimum, highly accurate eccentricity adjustment can be easily performed in a short time.

[Brief description of drawings]

FIG. 1 is a plan view of essential parts showing an embodiment of a hologram disc of the present invention.

FIG. 2 is a cross-sectional view of an essential part for explaining the method for manufacturing a hologram disc of the present invention.

FIG. 3 is a side view of the main parts for explaining the method of positioning the hologram disc according to the present invention.

FIG. 4 is a schematic diagram showing an enlarged image of an alignment pattern.

FIG. 5 is a main part plan view showing another embodiment of the hologram disc of the present invention.

FIG. 6 is a main part plan view showing another embodiment of the hologram disc of the present invention.

FIG. 7 is a main part plan view showing another embodiment of the hologram disc of the present invention.

FIG. 8 is a schematic view showing another embodiment of the alignment pattern.

FIG. 9 is a schematic view showing another embodiment of the alignment pattern.

FIG. 10 is a side view of essential parts showing another embodiment of the positioning method of the present invention.

FIG. 11 is a side view of essential parts showing another embodiment of the positioning method of the present invention.

FIG. 12 is a side view of essential parts showing an example of an optical scanning device using a hologram.

FIG. 13 is a side view of a main part for explaining eccentricity in an optical scanning device using a hologram.

FIG. 14 is a perspective view of a main part showing a conventional method of aligning a hologram disc.

FIG. 15 is a perspective view of a main part showing a method for manufacturing a conventional hologram disc.

[Explanation of symbols]

 10 Hologram Disc 12a-f Hologram Facet 14a-f Positioning Pattern 43 Rotation Drive Axis 45 Microscope (Image Magnifying Means) 46 CCD Camera (Magnifying Image Detecting Means)

Claims (5)

[Claims] 1. A hologram disc in which a plurality of hologram facets for scanning a light beam are arranged, wherein alignment patterns having different pitches depending on the radius are formed. 2. The hologram disc according to claim 1, wherein the radial pitch of the alignment pattern monotonically increases or decreases. 3. The hologram disc according to claim 1, wherein the alignment pattern is formed outside the hologram facet. 4. A step of observing an alignment pattern formed on a predetermined portion of the hologram disk, a step of positioning the hologram disk, and a step of fixing the hologram disk to a rotary drive shaft after the positioning. A method for positioning a hologram disc, comprising: 5. The hologram disc positioning method according to claim 4, wherein the pitch or the number of alignment patterns is detected in the observation step.