JP2008076571A - Hologram substrate, hologram substrate manufacturing method, and image projection apparatus - Google Patents

Abstract

An object of the present invention is to provide a hologram substrate capable of efficiently using irradiated laser light for projection of a reproduced image, a method for producing a hologram substrate capable of efficiently producing such a hologram substrate, and an image Providing a projection device.
A holographic substrate 1 is a holographic substrate 1 on which an image is formed by laser light irradiation, is formed on a surface opposite to a surface irradiated with laser light, and has an arbitrary shape by laser light diffraction. It has a hologram pattern 11 for projecting an image and a large number of minute irregularities 12 formed on the surface irradiated with laser light, and the average pitch between adjacent convexities of the irregularities 12, the width of the irregularities 12, and the irregularities The height difference of 12 is 30 to 50% of the wavelength of the laser beam.
[Selection] Figure 1

Description

  The present invention relates to a hologram substrate, a method for manufacturing a hologram substrate, and an image projection apparatus.

An image projection apparatus that projects a reproduced image of a hologram using laser light as a light source is known (see, for example, Patent Document 1).
This image projection device irradiates a hologram plate (hologram substrate) from a laser light source as a point light source, converts the laser light of the point light source into surface illumination by the hologram plate, and projects a reproduced image of the hologram pattern. .

In such an image projection apparatus, various hologram patterns are designed in order to improve the ratio of the amount of diffracted laser light to the amount of incident laser light, that is, the diffraction efficiency of laser light.
However, sufficient diffraction efficiency cannot be obtained only by designing the hologram pattern. In particular, the laser beam on the surface opposite to the surface on which the hologram pattern of the hologram plate is formed is reflected, and it is difficult to efficiently use the irradiated laser beam for projecting a reproduced image.

JP 2002-237990 A

  An object of the present invention is to provide a hologram substrate capable of efficiently using irradiated laser light for projection of a reproduced image, a method of manufacturing a hologram substrate capable of efficiently manufacturing such a hologram substrate, and an image projection apparatus. It is to provide.

Such an object is achieved by the present invention described below.
The hologram substrate of the present invention is a hologram substrate that forms an image by irradiation with laser light,
A hologram pattern that is formed on a surface opposite to the surface irradiated with the laser light, and projects the image of an arbitrary shape by diffracting the laser light;
A large number of minute irregularities formed on the surface irradiated with the laser light,
The average pitch of the convex portions adjacent to the concave and convex portions, the width of the concave and convex portions, and the height difference of the concave and convex portions are 30 to 50% of the wavelength of the laser beam.
Accordingly, it is possible to provide a hologram substrate that can efficiently use the irradiated laser light for projecting a reproduced image.

In the hologram substrate of the present invention, the surface roughness Rz (ten-point average roughness defined in JIS B 0601) of the surface on which the unevenness is formed is preferably 0.3 μm or less.
Thereby, reflection of the laser beam on the incident surface of the laser beam can be prevented or suppressed more effectively.
In the hologram substrate of the present invention, it is preferable that an average pitch between adjacent convex portions of the concave and convex portions, a width of the concave and convex portions, and a height difference of the concave and convex portions are 100 to 400 nm.
Thereby, reflection of the laser beam on the incident surface of the laser beam can be prevented or suppressed more effectively.

The hologram substrate manufacturing method of the present invention is a manufacturing method of manufacturing the hologram substrate of the present invention,
Providing a first mold having a shape corresponding to the hologram pattern on the surface;
Preparing a second mold having a shape corresponding to the irregularities on the surface;
And transferring the surface shapes of the first mold and the second mold to a substrate.
Thereby, a hologram substrate can be manufactured easily and simply. In addition, when the mold is used, it is possible to provide a hologram substrate having excellent mass production and quality in the case of mass production.

In the method for manufacturing a hologram substrate of the present invention, the second mold is preferably formed by blasting the surface of the base material.
Thereby, the shape corresponding to minute unevenness | corrugation can be formed more simply.
In the hologram substrate manufacturing method of the present invention, the blasting process is preferably wet blasting.
Thereby, the shape corresponding to minute unevenness | corrugation can be formed more simply.

The image projection apparatus of the present invention includes the hologram substrate of the present invention,
A laser light source for irradiating the hologram substrate with laser light is provided.
Thereby, the irradiated laser beam can be efficiently used for projecting a reproduced image, and an image projection apparatus capable of projecting a bright image can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a hologram substrate, a hologram substrate manufacturing method, and an image projection apparatus according to the invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a longitudinal sectional view schematically showing a hologram substrate of the present invention. In the following description, the right side in FIG. 1 is referred to as “(laser light) incident side” and the left side is referred to as “(laser light) emission side”.

The hologram substrate 1 is used, for example, as a member constituting an image projection apparatus 10 to be described later. As shown in FIG. 1, a hologram pattern 11 formed on a laser light emitting side surface and a laser light And a large number of minute irregularities 12 formed on the incident side surface.
The constituent material of the hologram substrate 1 is not particularly limited, but is mainly made of a resin material and made of a transparent material having a predetermined refractive index.

  Specific examples of the constituent material of the hologram substrate 1 include polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), cyclic polyolefin, modified polyolefin, polyvinyl chloride, poly Vinylidene chloride, polystyrene, polyamide (eg, nylon 6, nylon 46, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 6-12, nylon 6-66), polyimide, polyamideimide, polycarbonate (PC) , Poly- (4-methylpentene-1), ionomer, acrylic resin, acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-styrene copolymer (AS resin), butadiene-styrene copolymer Polyesters such as coalesced polyoxymethylene, polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycyclohexane terephthalate (PCT), polyether, poly Ether ketone (PEK), polyether ether ketone (PEEK), polyether imide, polyacetal (POM), polyphenylene oxide, modified polyphenylene oxide, polysulfone, polyether sulfone, polyphenylene sulfide, polyarylate, aromatic polyester (liquid crystal polymer) , Polytetrafluoroethylene, polyvinylidene fluoride, other fluororesins, styrene, polyolefin, polyvinyl chloride, Various thermoplastic elastomers such as urethane, polyester, polyamide, polybutadiene, trans polyisoprene, fluoro rubber, chlorinated polyethylene, epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester, silicone Resins, urethane-based resins, etc., or copolymers, blends, polymer alloys, etc. mainly composed of these, and combinations of one or more of these (for example, blend resins, polymer alloys, laminates) As body etc.).

The hologram pattern 11 has a function of converting incident laser light into a reconstructed image having an arbitrary shape by diffracting it.
The hologram pattern 11 has a shape designed based on a reproduced image to be converted (projected).
Further, as shown in FIG. 1, the hologram substrate 1 is provided with a large number of minute irregularities 12 on the surface on the laser beam incident side, that is, the surface opposite to the surface on which the hologram pattern 11 is formed. ing.
The large number of minute irregularities 12 have an average pitch (an average value of the pitch represented by P in the figure), an irregular width (a width represented by W in the figure), The condition that the height difference (the height difference represented by H in the figure) is 30 to 50% of the wavelength of the laser beam to be irradiated is satisfied.

  By the way, in an image projection apparatus equipped with a conventional hologram substrate, various hologram patterns are designed in order to improve the ratio of the amount of diffracted laser light to the amount of incident laser light, that is, the diffraction efficiency of laser light. However, sufficient diffraction efficiency cannot be obtained only by designing the hologram pattern. In particular, it is difficult to efficiently use the irradiated laser light for the projection of the reproduced image due to the reflection of the laser light on the surface opposite to the surface on which the hologram pattern is formed on the hologram substrate (laser light incident surface). It was.

  On the other hand, as in the present invention, the laser beam incident surface of the hologram substrate is provided with a large number of minute irregularities that satisfy the above conditions, thereby preventing the reflection of the laser beam on the laser beam incident surface. Can be suppressed. Thereby, since the light quantity of the laser beam which injects into the hologram pattern of a hologram substrate can be increased, diffraction efficiency can be improved. As a result, the irradiated laser light can be efficiently used for projecting a reproduced image. In addition, when providing such a large number of minute irregularities, there is an advantage that the wavelength range of the laser light that can provide the effect of antireflection is wider than that when an antireflection film that is normally used is provided. .

  As described above, the present invention has a large number of minute conditions that satisfy the condition that the average pitch of the convex portions, the width of the concave and convex portions, and the height difference of the concave and convex portions are 30 to 50% of the wavelength of the laser light irradiated on the incident surface. Although it has the feature in the point provided with the unevenness | corrugation, a minute unevenness | corrugation is 20-40% of the wavelength of the laser beam which the average pitch of the convex part, the width | variety of an unevenness | corrugation, and the height difference of an unevenness | corrugation irradiate. It is preferable to satisfy a certain condition, and it is more preferable to satisfy the condition of 25 to 35%. Thereby, reflection of the laser beam on the incident surface of the laser beam can be prevented or suppressed more effectively. On the other hand, if the average pitch of the convex portions, the width of the unevenness, and the height difference of the unevenness are less than the lower limit value, it is possible to sufficiently prevent or suppress the reflection of the laser light on the laser light incident surface. It can be difficult. On the other hand, if the average pitch between the protrusions, the width of the unevenness, and the height difference of the unevenness exceed the upper limit, the transmittance is lowered and the irradiated laser beam cannot be efficiently used for projection of the reproduced image. .

Specifically, the average pitch between the protrusions, the width of the unevenness, and the height difference of the unevenness are preferably 100 to 400 nm, and more preferably about 200 to 300 nm. Thereby, reflection of the laser beam on the incident surface of the laser beam can be prevented or suppressed more effectively.
Further, the surface roughness Rz (ten-point average roughness specified in JIS B 0601) of the surface provided with the minute irregularities 12 is preferably 0.3 μm or less, and is 0.2 to 0.3 μm. More preferably. Thereby, reflection of the laser beam on the incident surface of the laser beam can be prevented or suppressed more effectively.

Next, an image projection apparatus provided with the hologram substrate of the present invention will be described.
FIG. 2 is a schematic diagram of an image projection apparatus including the hologram substrate shown in FIG.
The image projection apparatus 10 includes the hologram substrate 1 described above and a laser light source 2 disposed on the light incident side of the hologram substrate 1.
In the image projector 10 configured as described above, the laser light La emitted from the laser light source 2 is incident on the surface of the hologram substrate 1 where the minute irregularities 12 are provided, and is diffracted by the hologram pattern 11. Is converted into a reproduced image.
Since the image projection apparatus 10 includes the hologram substrate 1 (the hologram substrate of the present invention), the incident laser light reaches the hologram pattern with sufficient transmittance. As a result, compared with the conventional one, the irradiated laser beam can be efficiently used for the projection of the reproduced image, and a sufficiently bright reproduced image can be projected.

Next, an example of a method for manufacturing a hologram substrate according to the present invention will be described.
3 is a longitudinal sectional view showing a first mold used for manufacturing the hologram substrate of the present invention, FIG. 4 is a longitudinal sectional view showing a second mold used for manufacturing the hologram substrate of the present invention, and FIG. These are figures which show an example of the manufacturing process of the hologram substrate of this invention.
The manufacturing method according to the present embodiment includes a first mold preparing step of preparing a first mold 3 having a shape corresponding to the hologram pattern 11 described above on the surface, and a first mold having a shape corresponding to the unevenness 12 described above on the surface. A second mold preparation step for preparing the second mold 4 and a transfer step for transferring the surface shapes of the first mold 3 and the second mold 4 to the substrate.

[First mold 3 preparation step]
First, as shown in FIG. 3, a first mold having a pattern 31 having a shape corresponding to the hologram pattern 11 described above is prepared on the surface.
The material constituting the first mold 3 is not particularly limited, and examples thereof include metal materials, glass, and resin materials. Among these, when a metal material is used, the workability and handleability of the first mold 3 are better.
The pattern 31 having a shape corresponding to the hologram pattern 11 is formed by, for example, a method of etching a master made of the above-described material through a mask having a predetermined opening, a laser processing method, or the like. can do.

[Second mold 4 preparation step]
On the other hand, as shown in FIG. 4, a second mold 4 having a large number of irregularities 41 having a shape corresponding to the minute irregularities 12 described above is prepared on the surface.
The material constituting the second mold 4 is not particularly limited, and examples thereof include a metal material, glass, and a resin material. Among these, when a metal material is used, the workability and handleability of the second mold 4 become better.

Such a second mold 4 can be manufactured by, for example, performing a predetermined process on the master made of the material as described above to form the unevenness 41.
The unevenness 41 can be formed, for example, by performing a blasting process such as air blasting, wet blasting, or sand blasting. Thereby, the shape corresponding to the unevenness | corrugation 12 mentioned above can be formed more easily.

Among the above, when the unevenness 41 is formed by wet blasting, the unevenness 41 can be formed more uniformly. Thereby, the shape corresponding to the unevenness | corrugation 12 mentioned above can be formed more easily.
Such blasting is preferably performed a plurality of times. Thereby, the unevenness | corrugation 41 can be formed more uniformly.
In addition, the average particle size of the fine particles sprayed on the master in blasting is preferably 10 μm or less, and more preferably 1 to 5 μm.

[Transfer process]
Next, as shown in FIG. 5A, the base material 13 made of the resin material as described above is placed between the first mold 3 and the second mold 4.
Next, the first mold 3 and the second mold 4 are heated, and the base material 13 is pressed as shown in FIG. 5B, and the shapes of the first mold 3 and the second mold 4 are changed. Transfer to the substrate 13.

And the base material 13 which transferred the shape of the 1st type | mold 3 and the 2nd type | mold 4 is cooled.
Thereafter, by removing the first mold 3 and the second mold 4, a hologram substrate 1 (hologram substrate of the present invention) as shown in FIG. 1 is obtained.
As described above, the hologram substrate 1 can be manufactured easily and simply by simultaneously transferring to the base material 13 using the first mold 3 and the second mold 4. In addition, when the mold is used, it is possible to provide the hologram substrate 1 with excellent quality and high quality in mass production.

As described above, the hologram substrate, the method for manufacturing the hologram substrate, and the image projection apparatus of the present invention have been described based on the illustrated embodiments, but the present invention is not limited to these.
For example, in the method for manufacturing a hologram substrate according to the present invention, an optional process can be added as necessary.

  In the above-described embodiment, the hologram substrate is manufactured using the second mold in which the shape corresponding to the minute unevenness of the hologram substrate is formed by blasting and the first mold for forming the hologram pattern. However, the holographic substrate may be provided with minute irregularities by directly blasting the substrate on which the hologram pattern is formed in advance without using the first mold.

In the above-described embodiment, the hologram pattern and the minute unevenness are formed almost simultaneously. However, the unevenness may be formed after forming the hologram pattern, or the hologram pattern is formed after forming the unevenness. May be.
In the above-described embodiment, the shape corresponding to the minute unevenness of the hologram substrate has been described as being formed by blasting. However, the present invention is not limited to this. For example, the hologram substrate is formed by etching, laser processing, or the like. It may be a thing.

(Example)
A hologram substrate was manufactured as follows.
First, the 1st type | mold comprised by the mirror surface stainless steel which has a pattern of the shape corresponding to the hologram pattern which should be formed was prepared.
On the other hand, a metal substrate made of mirror surface stainless steel having a smooth surface was prepared.
Next, minute irregularities were formed on the smooth surface of the metal substrate by wet blasting to form a second mold. The wet blasting was performed by uniformly spraying a dispersion liquid in which alumina having an average particle diameter of 5 μm was dispersed in water from the spray nozzle at a pressure of 0.2 MPa over the entire smooth surface. This wet blasting was performed twice. The average pitch of the formed uneven protrusions was 250 nm, the uneven width was 250 nm, and the uneven height difference was 250 nm. Further, the surface roughness Rz of the surface on which minute irregularities were formed was 0.25 μm.

Next, using the first mold and the second mold, the shape of each mold was transferred to a resin substrate made of polymethyl methacrylate (PMMA) by a hot press method in the same manner as in the above-described embodiment.
After cooling the resin substrate, each mold was peeled to obtain a hologram substrate.
The average pitch of the uneven portions formed on the laser light incident surface of the obtained hologram substrate was 250 nm, the uneven width was 250 nm, and the uneven height difference was 250 nm. Further, the surface roughness Rz of the incident surface was 0.25 μm.

(Comparative example)
A hologram substrate was manufactured in the same manner as in Example 1 except that a flat plate on which minute irregularities were not formed was used instead of the second mold. That is, a hologram substrate in which minute irregularities were not formed on the incident surface side was manufactured.

[Evaluation]
An image projection apparatus as shown in FIG. 2 was manufactured using the hologram substrates obtained in the examples and comparative examples. Note that a laser light source that irradiates laser light having a wavelength of 550 nm was used.
In the image projection apparatus according to the example and the comparative example, the light quantity A of the incident laser light and the light quantity B of the emitted laser light are measured, and the ratio of B to A, that is, the utilization efficiency (transmittance) of the laser light is obtained. Asked. As a result, in the image projection apparatus according to the example, the utilization efficiency was 91.3%, whereas in the comparative example, it was 88.1%.
As can be seen from this result, it was confirmed that the image projection apparatus according to the example can efficiently use the irradiated laser light for the projection of the reproduced image as compared with the comparative example.

It is the longitudinal cross-sectional view which showed typically the hologram substrate of this invention. It is a schematic diagram of the image projector provided with the hologram substrate shown in FIG. It is a longitudinal cross-sectional view which shows the 1st type | mold used for manufacture of the hologram substrate of this invention. It is a longitudinal cross-sectional view which shows the 2nd type | mold used for manufacture of the hologram substrate of this invention. It is a figure which shows an example of the manufacturing process of the hologram substrate of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Hologram substrate 11 ... Hologram pattern 12 ... Concavity and convexity 13 ... Base material 2 ... Laser light source 3 ... 1st type | mold 31 ... Pattern 4 ... 2nd type | mold 41 ... Concavity and convexity 10 ... Image projector

Claims (7)

A hologram substrate for forming an image by laser light irradiation,
A hologram pattern that is formed on a surface opposite to the surface irradiated with the laser light, and projects the image of an arbitrary shape by diffracting the laser light;
A large number of minute irregularities formed on the surface irradiated with the laser light,
A hologram substrate, wherein an average pitch between adjacent convex portions of the concave and convex portions, a width of the concave and convex portions, and a height difference of the concave and convex portions are 30 to 50% of a wavelength of the laser beam.   2. The hologram substrate according to claim 1, wherein a surface roughness Rz (ten-point average roughness defined in JIS B 0601) of the surface on which the unevenness is formed is 0.3 μm or less.   3. The hologram substrate according to claim 1, wherein an average pitch between adjacent protrusions of the unevenness, a width of the unevenness, and a height difference of the unevenness are 100 to 400 nm. A manufacturing method for manufacturing the hologram substrate according to any one of claims 1 to 3,
Providing a first mold having a shape corresponding to the hologram pattern on the surface;
Preparing a second mold having a shape corresponding to the irregularities on the surface;
And a step of transferring the surface shapes of the first mold and the second mold to the substrate.   The method of manufacturing a hologram substrate according to claim 4, wherein the second mold is formed by blasting a surface of a base material.   The method for manufacturing a hologram substrate according to claim 5, wherein the blasting is wet blasting. The hologram substrate according to any one of claims 1 to 3,
An image projection apparatus comprising: a laser light source for irradiating the hologram substrate with laser light.

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