JP2003270416A - Plastic-made optical element for head-up display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic-made optical element for a head-up display where a coat film with superior durability can be formed. <P>SOLUTION: At least one or more other surfaces 14 are formed between an outer circumferential surface 13 and an extension surface 12 and the width Δof the surfaces 14 is set to 0.01 to 10 mm when the surfaces 14 are viewed in parallel to the normal X in the center of an optical surface. Consequently, even when coat droplets are jetted from a sot source, no shadow in formed because of the presence of the surfaces 14, so the coat droplets become easy to fly around to the outer circumferential surface and as the sticking amount increases, the coat film thickness becomes larger to prevent water, etc., from entering, thereby suppressing trouble such as coat peeling. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element made of plastic, for example, a plastic optical element for a head-up display in which an optical surface or an extended surface thereof is coated with a thin film.

[0002]

2. Description of the Related Art The optical surface of an optical element created by molding a plastic material is usually coated with a thin film such as an antireflection coating, a reflection coating, or a protective coating for improving surface hardness or for preventing moisture. Is being done. Unlike optical materials such as glass, the materials for plastic optical elements are organic compounds, whereas most of these coating materials are inorganic materials, so the linear expansion coefficient, internal stress, and molecular composition The atomic structures and the like are greatly different between the two, and therefore adhesion and affinity are often poor. Moreover, since the plastic material used for the optical element has a low softening temperature of about 100 ° C., it is impossible to raise the substrate heating temperature when coating the optical surface by vapor deposition or the like. It is also difficult to improve.

In addition, among plastic materials for optical elements, acrylic and polycarbonate absorb moisture and swell, so that the coating on the surface of the optical surface cannot follow it and cracks or peeling may occur. Further, moisture absorbed by the plastic material may oxidize and swell a metal film such as aluminum or silver provided on the optical surface as a reflective coat, causing a remarkable decrease in reflectance and destruction of the coat layer. Therefore, it can be said that the reflective optical element obtained by molding the plastic material had a very large problem regarding the coating.

In order to prevent these, conventionally, silicon oxide (Si), which has relatively good adhesion, is used as an undercoat on the optical surface.
It has been performed that a layer for blocking moisture from a plastic material is provided by vapor deposition of O, SiO ₂ ) or the like, and an antireflection coating or a metal reflection coating is applied thereon. In addition, on the reflective optical surface, in order to prevent the metal reflection coating from being oxidized by humidity in the atmosphere and lowering the reflectance, silicon oxide or titanium oxide is further vapor-deposited on the metal reflection layer to form an atmosphere. It was common practice to apply a protective coat that blocks the Further, as an enhanced reflection coat, an alternate layer having a different refractive index such as silicon oxide and titanium oxide is provided,
It was also performed to protect the metal reflection surface and to increase reflection.

[0005]

What is important in the optical surface coating of an optical element formed by molding such a plastic material is that an appropriate coating material is used in order to perform the function that each thin film coating should play. Is to set the appropriate coating conditions, and to ensure the required coating film thickness with sufficient precision. However, even if such a condition is met, it has been found that, particularly when an environmental test is performed on a large-sized optical element or the like, the coat is peeled off from the periphery, cracked, or clouded.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a plastic optical element for a head-up display capable of forming a coat film having more excellent durability.

[0007]

A plastic optical element for a head-up display according to claim 1, wherein the plastic optical element for a head-up display has an optical surface molded from a plastic material. Or, at least one or more other surface is formed between the outer peripheral surface extending in the direction intersecting the extension surface and the optical surface and / or the extension surface thereof, and the other surface is the optical surface. The width of the other surface is 0.01 mm or more and 10 mm or less when viewed in the normal direction at the center of.

As a result of diligent research conducted by the present inventors, the following has been found. In a plastic optical element for a head-up display having a shape that does not have a flange on the outside of the optical surface, the extension surface of the optical surface extending from the optical surface toward the outer periphery and the outer peripheral surface used for fitting to the lens frame etc. 90
In many cases, they are sharply intersected at an angle close to each other to form a connection ridge (edge). However, when the droplets of the coat are ejected from the point source during the coating by vapor deposition or the like, the connection ridge line forms a shadow and the droplet cannot flow around the outer peripheral surface, so that the adhesion is insufficient. FIG. 1 shows a connection ridge line portion of a plastic optical element for a head-up display formed by the manufacturing method according to the conventional technique, which is observed with a microscope at a magnification of 300 times. The portion indicated by A in the figure looks like a ridge line macroscopically, but as can be seen from FIG. 1, it has an extremely incomplete microscopic shape, and a minute shadow is formed by Paris or burrs during coating, and It shows that uniform unevenness and film thickness are generated.

The reason for providing such a connecting ridgeline on the molded plastic optical element for head-up display is actually due to the structure of the molding die. In the molding die, the molding cavity has a structure in which a mold having an optical surface is inserted and fixed in a molding die set having an outer peripheral portion, and the part fitting portion forms this ridge line. is there. Since such a mold structure is easy to mold, it has been frequently used especially in a large-sized plastic optical element for a head-up display having no flange surface. However, the inventors of the present invention, when coating a plastic optical element for a head-up display molded with such a mold structure, even if the coating material and coating conditions are appropriately selected and a sufficiently dense thin film is formed,
The coating film thickness rapidly decreases in the vicinity of the connection ridgeline between the extended portion of the optical surface and the outer peripheral surface, so that the cross section of each coating layer is close to the state of being exposed to the atmosphere, and the intrusion of water and the like occurs from here. Then, they found that the coat peeled off and other problems occurred.

Therefore, in the plastic optical element for a head-up display, the present inventors have provided an outer peripheral surface extending in a direction intersecting with the optical surface and / or an extension surface thereof, and the optical surface and / or the optical surface. At least one or more other surface is formed between the extended surface and the width of the other surface is 0.01 mm or more when the other surface is viewed in the normal direction at the center of the optical surface. If the thickness is 10 mm or less, even if the coat droplet is ejected from the point source, the shadow cannot be shaded due to the existence of the other surface, so that the coat droplet easily wraps around the outer peripheral surface, and the coating amount increases as the adhesion amount increases. They have found that the coating film thickness is increased, which prevents the invasion of water and the like, thereby suppressing defects such as peeling of the coating film. The width of the other surface is 0.0
If it is less than 1 mm, the sufficient effect of the other surface cannot be obtained, and if it exceeds 10 mm, the effective surface of the plastic optical element for head-up display becomes small, which is not preferable.

In the plastic optical element for head-up display according to claim 2, at least one of the other surfaces is a flat surface, and the angle α formed by the flat surface and the outer peripheral surface, the optical surface and / or Or, an intersection angle θ between the extension surface and the outer peripheral surface (However, since the optical surface and / or the extension surface and the outer peripheral surface do not actually intersect, each surface is virtually extended and the intersection is formed. Since the upper side satisfies the following relationship, the presence of the other surface makes it easier for the coating droplets to wrap around, and the coating film thickness increases as the amount of adhesion increases. θ <α <180 degrees (1)

In the plastic optical element for a head-up display according to claim 3, since one of the other surfaces is formed along the outer edge of the optical surface and / or its extended surface, the other surface is formed. The presence of such a surface makes it easier for the coating droplets to wrap around, and the coating film thickness increases as the amount of adhesion increases.

In the plastic optical element for head-up display according to the fourth aspect, it is preferable that the optical surface and / or the extended surface thereof be coated with a thin film.

The plastic optical element for a head-up display according to claim 5 is a plastic optical element for a head-up display having a reflective optical surface molded from a plastic material, wherein the reflective optical surface and / or an extended surface thereof. Another surface is formed between the outer peripheral surface extending in the direction intersecting with and the reflective optical surface and / or its extended surface, and the different surface is in the normal direction at the center of the reflective optical surface. When viewed, the width of the other surface is 0.01
Since it is not less than 10 mm and not more than 10 mm, the coat droplet cannot be shaded due to the existence of the other surface, so that the coat droplet easily wraps around the outer peripheral surface, and the coating film thickness increases as the amount of adhesion increases.

According to a sixth aspect of the plastic optical element for a head-up display, at least one of the other surfaces is a flat surface, the angle α between the flat surface and the outer peripheral surface, the reflective optical surface, and Since the crossing angle θ between the extended surface and / or the outer peripheral surface satisfies the following relationship, the presence of the different surface makes it easier for the coating droplets to wrap around and the coating film thickness to increase as the amount of adhesion increases. Increase. θ <α <180 degrees (2)

According to a seventh aspect of the plastic optical element for head-up display, one of the other surfaces is,
Since it is formed along the outer edge of the reflective optical surface and / or the extended surface thereof, the presence of the other surface makes it easier for the coating droplets to wrap around, and the coating film thickness increases with an increase in the adhered amount. .

The plastic optical element for head-up display according to claim 8 is the reflection optical surface and / or
Alternatively, it is preferable that a thin film coat is applied to the extended surface thereof.

The plastic optical element for head-up display according to claim 9 is the reflection optical surface and / or
Alternatively, it is preferable that a reflection coat is applied to the extended surface thereof.

In the plastic optical element for head-up display according to the tenth aspect of the present invention, it is preferable that the reflective optical surface and / or the extended surface thereof is coated with a thin film and the reflective coating is further applied thereto.

In the plastic optical element for head-up display according to the eleventh aspect, it is preferable that the surface of the reflection coat is provided with a reflection enhancing coat or a protective coat.

In the plastic optical element for head-up display according to the twelfth aspect, it is preferable that aluminum or silver is used for the thin film coat.

According to a thirteenth aspect of the plastic optical element for head-up display, one of the other surfaces is a curved surface, and if the radius of curvature of an arbitrary portion is 0.3 mm or more and 100 mm or less, the other Because of the presence of
The coating droplets are more likely to wrap around, and the coating film thickness increases as the amount of coating increases.

According to a fourteenth aspect of the plastic optical element for head-up display, the angle between the outer peripheral surface and a normal line (not necessarily the optical axis) of the center of the optical surface is 4 degrees or more and 50. It is preferably less than or equal to the degree. This is because if the corners are in this range, the coat droplets will easily come around.

The plastic optical element for head-up display according to claim 15 is preferably a reflective optical element.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a perspective view of the plastic optical element for head-up display according to the present embodiment. FIG. 3 is a view of the plastic optical element for head-up display shown in FIG. 2 cut in a plane including a line III-III and viewed in a direction of an arrow.

In FIG. 2, a plastic optical element 10 for a head-up display, which is, for example, a reflection mirror.
Extends from the optical surface 11 and the outer edge of the optical surface 11 away from the optical axis of the optical surface 11 (in the embodiment, the optical surface 1
Since it has the same radius of curvature as 1, the clear boundary is not visually recognized. It is in a direction intersecting with the extension surface 12 and the extension surface 12, and is substantially parallel to the center normal line X (also referred to as the optical axis) of the optical surface 11. It has an outer peripheral surface (also referred to as a side surface) 13 and a surface (another surface) 14 formed between the extension surface 12 and the outer peripheral surface 13. That is, the surface 14 is formed along the outer edge of the extension surface 12. The optical surface 11 and the extension surface 12 are coated with a reflective film containing aluminum or silver as a component.

In FIG. 3, the width Δ of the surface 14 is determined by the optical surface 1
When viewed in the direction of the center normal line X of 1, the distance from the boundary with the outer peripheral surface 13 to the boundary with the extension surface 12 is preferably 0.01 mm or more and 10 mm or less. If the angle between the surface 14 and the outer peripheral surface 13 is α, and the angle between the surface 13 and the extended surface 12 (the surfaces extended from each other as indicated by the dotted line, the same applies below) is θ, then θ <α <180 degrees (1) holds. However, this relationship is not an essential requirement. If the surface 14 does not exist, the outer peripheral surface 13 and the extension surface 12 virtually intersect at a point P, and the connection ridge line (the one-dot chain line in FIG. 2) that makes one round along the plastic optical element 10 for head-up display. PL). In the conventional plastic optical element for head-up display, as described above, the connection ridge (PL) causes a defect such as peeling of the reflection coat film.

(Examples) The present inventors conducted an environmental test in Comparative Examples and Examples in order to confirm the effects of the present invention. The result will be explained. First, a plurality of optical elements as comparative examples having connection ridges were molded from plastic. Further, among the molded optical elements, an optical element having an undercoating coating and an antireflection coating, and an optical element having an undercoating coating, a reflection coating, and a protective coating thereof are manufactured so as to satisfy desired initial characteristics. did. The optical elements of these comparative examples were subjected to a high temperature and high humidity test at 70 ° C., a relative humidity of 90% Rh for 500 hours, and a maximum temperature of 90 ° C. to a minimum temperature of −30.
When it was put into a thermal cycle test in which heating and cooling were repeated 100 times for 1 hour in 2 hours to ℃, peeling and cracking of the coat occurred from the outer edge of the extension surface, and finally defects that grew on the optically effective surface Entered, and the function as an optical element was no longer satisfied. In particular, in the case of a reflective optical element with vapor-deposited aluminum, not only did the environmental test oxidize aluminum from the outer edge to significantly reduce the reflectance, but also the coating layer itself was destroyed by the volume change when changing to alumina. It became cloudy and became no longer an optical surface.

The fact that is common to the results of these environmental tests is that defects that occur on the coated surface always start from the outer edge of the extended surface, and that the defective portion grows inward continuously, so that it does not occur at the center of the optical surface. Is that it does not exist at all.

From the above, the inventors of the present invention can secure a sufficient coating film thickness in the vicinity of the connection ridgeline between the extended surface of the optical surface and the outer peripheral surface, and the antireflection coating layer and the reflection coating layer can be sufficiently protected from the plastic material and the atmosphere. It has been found that, if it is blocked and no defect occurs, the coating layer can be protected from the occurrence of defects on the entire optical surface and the optical surface can be maintained.

Therefore, the inventors of the present invention provide another surface in order to prevent the shadow of the coat droplet ejection source (not shown) from being shaded by the existence of the connecting ridgeline between the extended surface of the optical surface and the outer peripheral surface. Figured out. More specifically, the outer peripheral portion of a mold (not shown) in which the optical element of the comparative example is molded is widened by 2 mm, that is, 4 mm by passing it over, and a 45 degree inner chamfer from the fitting portion with the optical surface nesting mold is directed toward the outer peripheral surface. With a width of 2 mm, a plastic optical element 10 for head-up display shown in FIGS. Where extension 1
The normal angle β of 2 (angle formed with the optical axis) is 2 in this embodiment.
Since the draft γ of the outer peripheral surface is 3 degrees at 5 degrees, the extension surface 12
The angle θ formed by the outer peripheral surface 13 is 65 degrees + 3 degrees = 68 degrees. Therefore, the newly provided chamfered plane has a relationship that the angle α of the surface 14 with respect to the outer peripheral surface 13 direction is 135 ° + 3 ° = 138 °, which is smaller than 180 ° and larger than 65 ° (θ) with respect to the outer peripheral surface direction. Will be satisfied. As a result, the optical surface 11 of the molded plastic optical element 10 for head-up display has its extension surface 12
Is connected to the outer peripheral surface through the surface 14 at an obtuse angle, so that it is relieved that the edge of the outer peripheral surface 13 is shaded with respect to the coat spray ejection source during coating, and the vapor deposition substance gradually wraps around the outer peripheral surface 13 and rapidly. Of the film thickness is prevented, and the film thickness on the outer peripheral surface 13 is gradually reduced.

An optical element as an example shown in FIGS. 2 and 3 was molded, further coated with a reflection coat, and put into the same environmental test as the comparative example. As a result, both a high temperature and high humidity test of 70 ° C., a relative humidity of 90% Rh and 500 hours, and a thermal cycle test in which heating and cooling were repeated 100 times in 2 hours from a maximum temperature of 90 ° C. to a minimum temperature of −30 ° C., No cracks or peeling occurred, and the aluminum of the reflection coat did not fog at all. The provision of this surface 14 eliminates the above-mentioned connection ridgeline that forms an acute angle. Therefore, it is possible to secure a sufficient thickness of the coating layer on the outer peripheral surface 13 by the droplets from the coating droplet spraying source during coating. all right.

As can be seen from the above, the plastic optical element 1 for a head-up display has the functions of the undercoat and the protective coat due to the unique constitution of the present invention.
It is possible to maintain even the outer peripheral surface 13 of 0, the occurrence of coat defects depending on environmental conditions can be significantly reduced, and the optical performance thereof can be maintained for a long period of time.

In the present specification, the term "optical surface" is used to mean a surface in the effective range where the optical function is exerted. Therefore, in the case where the entire one surface of the plastic optical element for head-up display is set as the effective range. Does not have an extended surface, only an optical surface. Further, the present invention is realized regardless of the number of the surfaces 14 provided at the connecting portion between the optical surface 11 or the extension surface 12 and the outer peripheral surface 13. Further, it does not matter whether the surface 14 is a flat surface or a curved surface. The example is a plane because the molding die can be easily additionally processed, and the surface newly provided in the connection portion has a function of eliminating the connection ridge line that makes a shadow during coating, This is within the scope of the present invention. When the surface 14 is a curved surface, the radius of curvature of any part (or all) may be 0.3 mm or more 10
It is preferably 0 mm or less. This is because if the radius of curvature is smaller than 0.3 mm, most of the ridge lines are formed, so the above-described effect of the present invention is low, and if it exceeds 100 mm, it is almost the same as when it is made flat. Further, the coat is not limited to the reflective film, and various thin films such as a reflection enhancing coat, a protective coat, an infrared absorbing film can be applied. In addition, the present invention is not limited to plastic optical elements for head-up displays,
It can also be applied to ordinary optical elements.

[0035]

According to the present invention, it is possible to provide a plastic optical element for a head-up display, which can form a coated film having more excellent durability.

[Brief description of drawings]

FIG. 1 shows a connection ridge portion of a plastic optical element for a head-up display, which is formed by a conventional manufacturing method.
It is a figure which shows the state observed at a magnification of 300 with a microscope.

FIG. 2 is a perspective view of a plastic optical element for a head-up display according to the present embodiment.

FIG. 3 is a view of the plastic optical element for head-up display of FIG. 2 taken along a line including a line III-III and viewed in the direction of an arrow.

[Explanation of symbols]

10 plastic optical element for head-up display 11 optical surface 12 extended surface 13 outer peripheral surface 14 surface (another surface)

Continued front page    (72) Inventor Shiro Tanaka             886, Shinba-cho, Kohoku-ku, Yokohama-shi, Kanagawa             Iki Plastic Industry Co., Ltd. Yokohama Factory F-term (reference) 2H042 DA02 DA04 DA11 DA19 DC02                       DC08 DD05 DE00                 3D044 BA01 BC25 BD13

Claims (15)

[Claims] 1. A plastic optical element for a head-up display, which has an optical surface molded from a plastic material, and an outer peripheral surface extending in a direction intersecting the optical surface and / or an extension surface thereof, and the optical surface and / Or at least one other surface is formed between the other surface and the extension surface, and the width of the other surface is 0 when the other surface is viewed in the normal direction at the center of the optical surface. 0.01 mm or more 10
A plastic optical element for a head-up display, which is less than or equal to mm. 2. At least one of the other surfaces is a flat surface, and an angle α between the flat surface and the outer peripheral surface and an intersection angle θ between the optical surface and / or its extension surface and the outer peripheral surface. Satisfies the following relation: The plastic optical element for head-up display according to claim 1. θ <α <180 degrees 3. One of the other surfaces is the optical surface and / or
Alternatively, the plastic optical element for head-up display according to 1 or 2, which is formed along the outer edge of the extended surface thereof. 4. The plastic optical element for a head-up display according to any one of claims 1 to 3, wherein the optical surface and / or its extended surface is coated with a thin film. 5. A plastic optical element for a head-up display, which has a reflective optical surface formed of a plastic material, and an outer peripheral surface extending in a direction intersecting with the reflective optical surface and / or an extended surface thereof, and the reflective surface. When another surface is formed between the optical surface and / or its extension surface and the other surface is viewed in the normal direction to the center of the reflective optical surface, the width of the other surface is 0. 01 mm or more and 10 mm
A plastic optical element for head-up display, characterized in that: 6. At least one of the other surfaces is a flat surface, and an angle α between the flat surface and the outer peripheral surface and an intersection angle θ between the reflective optical surface and / or its extended surface and the outer peripheral surface. And the following relationship is satisfied: The plastic optical element for head-up display according to claim 5, wherein θ <α <180 degrees 7. The head-up display according to claim 5, wherein one of the other surfaces is formed along an outer edge of the reflective optical surface and / or an extended surface thereof. A plastic optical element. 8. The plastic optical element for a head-up display according to claim 5, wherein the reflective optical surface and / or an extended surface thereof is coated with a thin film. 9. The plastic optical element for a head-up display according to claim 8, wherein the reflective optical surface and / or an extended surface thereof is provided with a reflective coat. 10. The plastic optical element for a head-up display according to claim 8, wherein the reflective optical surface and / or the extended surface thereof is coated with a thin film, and the reflective coating is provided thereon. element. 11. The plastic optical element for a head-up display according to claim 9, wherein the surface of the reflection coat is provided with a reflection enhancing coat or a protective coat. 12. The plastic optical element for a head-up display according to claim 4, wherein aluminum or silver is used for the thin film coat. 13. The head-up according to claim 1, wherein one of the other surfaces is a curved surface, and a radius of curvature of an arbitrary portion thereof is 0.3 mm or more and 100 mm or less. Plastic optical element for display. 14. The head-up display according to claim 1, wherein an angle formed by the outer peripheral surface and a normal line of the center of the optical surface is 4 degrees or more and 50 degrees or less. Optical element for plastics. 15. The plastic optical element for a head-up display according to claim 1, which is a plastic optical element for a reflective head-up display.