JPS6217721B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a retroreflector and a method for manufacturing the same.

A retroreflector is known, which is formed by inserting a plurality of glass spherical reflective elements into a plastic plate. Conventional retroreflectors have the disadvantage of high manufacturing costs because a large number of spherical reflective elements are manufactured and inserted into a plastic plate.

However, a more serious drawback of conventional retroreflectors is their low reflective brightness. Also,
Reverse reflectors used in transportation systems such as roads and highways must be able to reflect obliquely incident light rays in the opposite direction parallel to the incident light rays within a specified angular range. In the case of a conventional retroreflector, to achieve this, the diameter of the spherical reflective surface at the face opposite the input surface of each spherical reflective element is equal to the diameter of the spherical reflection surface at the input surface. It had to be larger than the diameter of the surface. This means that the reflective elements cannot be successively coupled next to each other on the input side. Furthermore, on the reflective side it is necessary to place a plastic web between each reflective element in order to hold each reflective element on the plastic plate. This makes the optically active surface even smaller. For the reasons mentioned above, only about one-third of the total surface of retroreflectors actually used is optically active. On the other hand, if the spherical reflective elements were connected successively adjacent to each other, the shape of each reflective surface would have to match the shape of the light entrance surface, and therefore the angular regulations would not be met. Become.

The reflector described in German Patent Publication no. There are areas that are optically inactive. Therefore, the luminous intensity will inevitably decrease.
Furthermore, the light entrance surface has the same design as the reflection surface. Therefore, obliquely incident light rays that do not hit the reflective surface are not reflected. Therefore, reflection over a wide angular range is not possible.

In the reflector described in Austrian Patent No. 332763, the entire surface is covered, but most of the obliquely incident light rays are not reflected parallel to the light rays (hereinafter referred to as "reflected parallel to the incident light rays in the opposite direction"). (This is called retroreflection.) Therefore, the angle is still not satisfactory.

The reflector described in German Patent Publication No. 1932259 has an improved reflection angle range since the reflection surface is larger than the light entrance surface. However, in the case of the reflective elements of this reflector plate, it is impossible to cover the entire surface on the light incident side. Even if the reflective side is completely covered by the reflective surface, there will still be an optically inactive portion on the light incident surface side, which will still reduce the luminous intensity.

U.S. Pat. No. 2,243,434 describes various examples of light entrance surfaces and reflective surfaces. However, even in this patent, the entire surface cannot be covered, and the range of angles that can be reflected cannot be increased.

As described above, in the past, it has not been possible to satisfy both the requirement of expanding the reflective angle range and the requirement of increasing luminous intensity. Conventional reflectors either have deficiencies in their ability to retroreflect obliquely incident light, which is required in many applications, or their luminous intensity is low because the entire light input surface is not optically active. Either it had a defect of being low.

In view of these circumstances, the present invention has high luminous intensity,
Moreover, it is an object of the present invention to provide a retroreflection plate that can perform retroreflection over a wide range of angles.

The retroreflector of the first invention is comprised of a transparent plate whose back surface is a reflective surface, the front surface of the transparent plate is comprised of a plurality of curved light incident surfaces arranged adjacent to each other, and the rear surface is comprised of a plurality of curved light incident surfaces arranged adjacent to each other. is composed of a plurality of curved reflective surfaces arranged adjacent to each other, the optical axis of each of the light incident surfaces coincides with the optical axis of each of the reflective surfaces, and the surface of the transparent plate is horizontally projected. When each of the light incident surfaces and the reflective surface are vertically projected as a surface, the plurality of reflective surfaces include a large number of reflective surfaces with two types of different areas, and the area of each reflective surface is the same as the light incident surface. It is characterized in that the area is different from the area of the incident surface.

The retroreflector of the second invention consists of a transparent plate whose back surface is a reflective surface, the front surface of the transparent plate is composed of a plurality of curved light incident surfaces arranged adjacent to each other, and the rear surface is composed of a plurality of curved reflective surfaces arranged adjacent to each other, the optical axis of each of the light incident surfaces coincides with the optical axis of each of the reflective surfaces, and the surface of the transparent plate is horizontally projected. The light incident surface and the reflective surface are characterized in that, when the light incident surface and the reflective surface are projected perpendicularly, the areas of the light incident surface and the reflective surface are approximately equal, and their contours are different from each other.

The first invention will be explained in detail below. In this first invention, it is desirable that the transparent plate has two types of reflective surfaces of different shapes.

Also, in order to maximize the luminous intensity, the front and back surfaces of the transparent plate are almost completely covered by a light incident surface and a reflective surface, respectively.

Further, it is preferable that the outer shape of the light incident surface is hexagonal.

Further, the area and shape of the outline of the light entrance surface or the reflection surface refer to the outline when the light entrance surface or the reflection surface is vertically projected onto the transparent plate as a horizontal projection surface.

In the case of conventional reflectors, the size of the light incident surface is either equal to or smaller than the size of the reflective surface. On the other hand, in the reflector of the first aspect of the invention, the size of the light incident surface may be larger than the reflecting surface corresponding to the light incident surface.

That is, the reflecting plate of the first invention has a reflecting surface that has an area necessary to reflect all the light incident from the corresponding light incident surface, and a reflecting surface that reflects only a part of the light incident from the corresponding light incident surface. The latter is made larger by sacrificing the size of the adjacent reflective surface. Therefore, for example, large reflective surfaces and small reflective surfaces are arranged alternately.

The large reflective surface is made considerably larger in at least one direction than the corresponding light entrance surface and therefore also reflects obliquely incident light rays at a considerably large angle. Therefore, the reflector of the present invention can retroreflect light over a wide angular range. A small reflective surface, on the other hand, can only reflect light rays that are incident at relatively small angles, but the main portion of the light rays are incident at relatively small angles. In the reflector of the present invention, as described above, the incident side and reflective side are completely covered by the incident surface and the reflective surface, respectively, so that the luminous intensity is extremely high.

It is also desirable to provide two types of reflective surfaces with different shapes. In this case, in order to cover the entire surface of the incident side and the reflective side, the sum of the areas of the two types of reflective surfaces is usually equal to the sum of the two corresponding light incident surfaces.

The light entrance surface and the reflection surface may have the same contour, for example a hexagonal contour. However, there is no problem even if the outlines of the two are different.
For example, the light incident surface may have a square outline, and the reflecting surface may have an octagonal or square outline.

In the second invention, it is preferable that the light incident surface has a hexagonal, square or rectangular outline, and the reflective surface has a rectangular outline.

In the reflective plate of the second aspect of the invention, it is desirable that its back side be completely covered by a plurality of adjacent reflective surfaces. The area of each reflective surface is equal to the area of the light entrance surface, but they have different contours.

By changing the contour of the reflective surface relative to the light entrance surface, the reflective area can be easily varied and the reflector can therefore be easily adapted to the desired conditions. With such an optical structure,
The range of change in the reflective area can be made extremely large, and high luminous intensity can be maintained. Therefore, it can be adapted to desired environmental conditions and specifications.

The first invention and the second invention are identical in that the light entrance side is completely covered by a plurality of curved light entrance surfaces arranged adjacent to each other. This causes all light hitting the reflector to be reflected back. This is a dead area between each light incident surface,
That is, this is impossible when there is an optically inactive region. Such full surface coverage is particularly easy if the outline of the light incident surface is square, rectangular, parallelogram, hexagonal, etc.

The features of the first invention and the features of the second invention may be used in combination. For example, if the reflective surface
According to the first invention, the contour is different from that of the light incident surface, for example, it is elongated, and further, according to the first invention, some of the reflective surfaces are formed such that, for example, a reflective surface adjacent to every other or every other row of reflective surfaces is formed. It is also possible to increase the area by sacrificing the area. This allows the angular range of reflection to be further enlarged.

Each reflective surface corresponds to a light incident surface,
The optical axis of the reflective surface and the optical axis of the light incident surface coincide with each other.

Normally, both optical axes are perpendicular to the reflector. In applications such as attaching signs to the ground, it is desirable to make the reflection characteristic curve non-uniform by tilting the optical axis of the reflector with respect to the direction perpendicular to the reflector.

It is also desirable that the opposite side of the reflective surface be completely covered by the adjacent reflective surface.

In many cases, for example when using retroreflectors on roads, it is required that they be optically active within a certain angular range. For example, reflective ability is required over an extremely wide angular range in the horizontal direction, but the required angular range is relatively narrow in the vertical direction. According to the retroreflector of the present invention, such requirements can be met extremely well and easily. The range of angles that can be reflected by the retroreflector is approximately proportional to the size of the reflecting surface. By changing the contour of the reflecting surface, such as by making it into an elongated hexagonal shape, or by changing the area of the reflecting surface, for example, the range of angles in which reflection can be performed in the horizontal direction can be greatly expanded. I can do it. The reflector of the present invention can take such measures, and can completely cover both the incident side and the reflective side with the light incident surface and the reflective surface, respectively.

In order to achieve the desired retroreflection area, it is conceivable to have a special design of the planar geometry of the light entrance surface. For example, the light incident surface may have a hexagonal shape elongated in the length direction, or the arrangement pattern of the elements may be changed.

In the retroreflector of the present invention, the relationship between the light incident surface and the reflective surface can be easily changed by changing the planar shape, and the arrangement pattern of the reflective surface can also be easily changed. The characteristic curve of reflection can be made as desired. Therefore, the retroreflector of the present invention can be adapted very well to desired conditions. Furthermore, the reflective area can be varied over a very large range, and the luminous intensity can also be made extremely high.

Furthermore, the retroreflector of the present invention can be manufactured extremely easily and at low cost.

For manufacturing technical reasons, it is desirable to round the corners of the curved reflective surface. The effect of this on the incident light is extremely small. Moreover, compared to such a small influence, the manufacturing benefits are extremely large.

Although the retroreflector of the present invention can be used in a wide variety of fields, it is particularly suitable for use on roads due to its optical properties and resistance to the effects of adverse weather conditions.

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 7 show a retroreflection plate according to a first embodiment of the present invention.

The retroreflector 1 shown in FIG. 1 has hexagonal light incident surfaces 4a and 4b on the front surface 3. The retroreflector 1 shown in FIG. The light incident surfaces 4a and 4b may be exactly the same, but may have different shapes for reasons described later.

Each light entrance surface 4a, 4b corresponds to a reflection surface 5a, 5b, respectively, and the optical axis 6 of the corresponding light entrance surface and the optical axis 7 of the reflection surface coincide (in FIG. 1, the reflection surface is indicated by a broken line).

The retroreflector 1 of this embodiment has reflective surfaces 5a and 5b on the back surface 2, as shown in FIG. In the case of this embodiment, the area of the reflective surface 5a is considerably larger than the area of the reflective surface 5b.

FIG. 3 is a cross-sectional view taken along the line A-A in FIG.
4b is provided, and reflective surfaces 5a and 5b are provided on the back surface 2. As clearly shown in FIG. 3, the optical axis 6 of the light entrance surfaces 4a, 4b
coincide with the optical axis 7 of the reflecting surfaces 5a and 5b, respectively. The incident light 10 is reflected from the reflective layer 9 in parallel.

In other embodiments of the first invention shown in FIGS. 4, 5 and 6, the light incident surfaces 4a and 4b are square shaped, and the reflective surfaces 5a and 5b are octagonal and square shaped, respectively. .

As shown in FIG. 4, the corners of the square are cut off due to the difference in curvature of the entrance surfaces 4a and 4b.

Next, a retroreflector according to a second embodiment of the present invention will be described with reference to FIGS. 8 to 14.

The retroreflector 1 shown in FIG. 8 has a plurality of regular hexagonal light incident surfaces 4 on the front surface 3. The retroreflector 1 shown in FIG.

Each light entrance surface 4 corresponds to a reflection surface 5, and the optical axis 6 of each light entrance surface 4 coincides with the optical axis 7 of the corresponding reflection surface 5.

The reflective surface 5 has a rectangular shape, and its area matches the area of the hexagonal light entrance surface 4. The short side of the reflective surface 5 has a length that is half the distance between the opposite sides of the light incidence surface 4, and the long side is equal to the length of the diagonal of the hexagon of the reflective surface 5. It has a length equal to the length plus the length.

Optical activity is determined by the dimensions of the reflective surface. The angular range over which reflection occurs is proportional to the size of the rectangle.

FIG. 9 is a plan view of the retroreflector 1 shown in FIG. 8, viewed from the rear surface 2 side.

FIG. 10 is a sectional view taken along the line A--A in FIG. 8. FIG. 10 shows that the light incident surface 4 is arranged on the front surface 3 of the retroreflector 1, and the reflective surface 5 is arranged on the back surface 2. Optical axis 6 of light incidence surface 4 and reflection surface 5
It coincides with the optical axis 7 of. Incident light 10 passes through reflective layer 9
reflected in the opposite direction.

FIG. 11 is a sectional view taken along the line B--B in FIG. 8. As is clear from a comparison with FIGS. 3 and 4, FIG. 11 shows a different embodiment having a hexagonal light entrance surface 4 and a rectangular reflection surface 5.

In the retroreflector of the embodiment shown in FIG. 12, the light incident surface 4 has a regular hexagonal shape, and the reflecting surface 5
has an outline like a hexagon with a rectangle added to both ends.

In the embodiment shown in FIG. 13, the light incident surface 4 has an elongated hexagonal shape, and the reflective surface 5 has an extremely elongated rectangular shape. In embodiments of this type, in which the light entrance surface 4 is extended in one direction, reflection over a very wide angular range is possible if both sides are completely covered.

In the embodiment shown in FIG. 14, the light entrance surface 4 has a square shape, and the reflection surface 5 has a rectangular shape.
It is clear that when the light entrance surface is square or rectangular, the dimensions of the rectangular reflecting surface can be varied widely. In addition, when the light entrance surface is square or rectangular, it is necessary to shift the position every other row, and the midpoint of each light entrance surface must not be aligned in the direction of the long side of the rectangular reflection surface. In the embodiment shown in FIG. 14, the corners 8 of the rectangular reflecting surface 5 are cut off and rounded.

Since the optical structure that forms the basis of the present invention is well known, detailed explanation will be omitted. Its optical structure is described in the aforementioned patents.

The light entrance surface may be spherical or aspherical. The reflective surface is usually a spherical surface. The curvature of the light entrance surface depends on the refractive index of the material used and the desired degree of dispersion of the reflected light.

If the light is incident at a large angle, for example 25° or more, it is advantageous to use a dynamically balanced stepped mirror as the reflective surface. In the embodiment shown in FIG. 7, the reflective surface 5a is a stepped mirror 12.

In FIG. 2, the reflective surface 5a is larger than the reflective surface 5b. When the incident surfaces are optically equal, a step is required between the reflecting surfaces due to the optical structure. This stage 11 is shown in FIG.

If necessary, this step can also be eliminated by reducing the radius of curvature of the corresponding light entrance surface. This is shown in dashed lines in FIG.

Further, the corresponding light entrance surface may be made to protrude without changing the radius of curvature of the light entrance surface. At this time, the vertices of each light incident surface are no longer located on the same plane.

As mentioned above, since the radius of curvature of each light entrance surface changes every other time, the split image of each light entrance surface also changes. Instead, the entrance surface 4 has a different form.
a and 4b are provided.

The reflecting plate of the above embodiment has two types of reflecting surfaces 5a, 5.
It is equipped with b. However, three or more types, for example, four types of reflective surfaces may be used.

Transparent materials particularly suitable for the retroreflector of the present invention include cellulose esters such as cellulose acetate and cellulose vityrate, synthetic materials such as polymethyl methacrylate, acrylic glass, and polystyrene. Note that the retroreflector of the present invention can be manufactured using a plastic film instead of a plastic plate, and in this specification, the term "plate" includes a film.

The thickness of the plate basically depends on the radius of curvature of the optical surface, but is preferably 2 to 10 mm.
From a cost standpoint, it is desirable that the plate be as thin as possible.

The degree to which the light incidence side is divided by the light incidence surface can be selected within a relatively wide range.
It depends on the refractive index of the material used, the thickness of the reflector, and the desired optical structure.

The height of the curved light entrance surface is approximately determined by the degree of division. The height of the light incident surface is 0.5
It is desirable that the thickness be ~2 mm.

The reflective layer 9 may be formed of any reflective material, and may be coated with silver or aluminum, but it is preferable to provide the reflective layer 9 in the form of an aluminum foil.

When manufacturing the parallel reflector of the present invention, a metal foil such as aluminum foil is inserted into a mold such as an injection mold, and a plastic material for the plate is injected into the mold (the light incident surface and the reflective surface are separated). It is preferable to mold a plate with At the same time, the plate and the metal foil are fused together at high temperatures. Note that, if necessary, the metal foil may be coated with a transparent plastic.

The present invention can also be reversed by heating a strip-shaped plastic body with a metal foil embedded therein or a strip-shaped plastic body with a metal foil pasted on the surface to a processable state, and stamp-molding it using an appropriate mold. A directional reflector may also be manufactured.

Alternatively, after a transparent plastic plate is formed by injection molding, a reflective layer may be provided on the plate by vapor deposition of aluminum under high vacuum.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a reflector according to an embodiment of the first invention, as seen from the light incident side, FIG. 2 is a plan view as seen from the reflection side, and FIG. 3 is a line taken along line A-A in FIG. 1. A sectional view, FIG. 4 is a plan view of a reflector of another embodiment as seen from the light incident side, FIG. 5 is a plan view as seen from the reflection side, and FIG.
The figures are a cross-sectional view taken along the line A-A in FIG. 4, FIG. 7 is a cross-sectional view of the reflector, FIG. Figure 9 is a plan view as seen from the reflection side, Figure 10 is a cross-sectional view taken along line A-A in Figure 8, Figure 11 is a cross-sectional view taken along line B-B in Figure 8, and Figures 12 to 14 are light incident views. FIG. 6 is a diagram illustrating examples of various combinations of contours of surfaces and reflective surfaces. 2...Back side, 3...Front side, 4, 4a, 4b...
Light incidence surface, 5, 5a, 5b...Reflection surface, 6, 7...
...Optical axis, 9...Reflection layer.

Claims (1)

[Scope of Claims] 1. Consisting of a transparent plate whose back surface is a reflective surface, the front surface of the transparent plate is composed of a plurality of curved light incident surfaces arranged adjacent to each other, and the rear surface is composed of a plurality of curved light incident surfaces arranged adjacent to each other. The optical axis of each of the light incident surfaces coincides with the optical axis of each of the reflective surfaces, and the surface of the transparent plate is used as a horizontal projection surface to project each of the light beams. When the incident surface and the reflective surface are projected perpendicularly, the plurality of reflective surfaces include a large number of two types of reflective surfaces having different areas, and the area of each reflective surface is equal to the area of the light incident surface. A reverse reflector characterized by being different from the above. 2. The reflecting plate according to claim 1, wherein the plurality of reflecting surfaces are composed of two types of reflecting surfaces having different shapes. 3. The reflecting plate according to claim 2, wherein the sum of the areas of the two reflecting surfaces including the two types of reflecting surfaces having different shapes is equal to the sum of the areas of the two light incident surfaces. . 4. The reflecting plate according to any one of claims 1 to 3, wherein the outline of the reflecting surface is different from the outline of the incident surface. 5. The reflecting plate according to any one of claims 1 to 4, wherein each of the reflecting surfaces has a different contour. 6. Any one of claims 1 to 5, wherein the front surface of the transparent plate is almost completely covered by the light entrance surface.
Reflector plate as described in section. 7. The reflective plate according to any one of claims 1 to 6, wherein the rear surface of the transparent plate is almost completely covered by the reflective surface. 8. The reflecting plate according to any one of claims 1 to 7, wherein the plurality of light entrance surfaces are comprised of light entrance surfaces of different shapes having different radii of curvature. 9. The reflecting plate according to claim 8, wherein the plurality of light entrance surfaces are comprised of two types of light entrance surfaces. 10. The reflecting plate according to any one of claims 1 to 9, wherein the outline of the light incident surface is hexagonal, square, or rectangular. 11. The reflective plate according to any one of claims 1 to 10, wherein the reflective surface has a rectangular outline. 12. The reflecting plate according to any one of claims 1 to 11, wherein the outer corner of the reflecting surface is rounded off. 13. Claims 1 to 12, characterized in that the optical axes of the light incident surface and the reflective surface are inclined with respect to a direction perpendicular to the surface of the transparent plate.
The reflector plate according to any one of paragraphs. 14. Any one of claims 1 to 13, wherein the transparent plate is a plastic plate or a plastic sheet.
Reflector plate as described in section. 15 Consisting of a transparent plate whose back surface is a reflective surface, the front surface of the transparent plate is composed of a plurality of curved light incident surfaces arranged adjacent to each other, and the rear surface is composed of a plurality of curved light incident surfaces arranged adjacent to each other. The optical axis of each of the light incident surfaces coincides with the optical axis of each of the reflective surfaces, and the light incident surface and the reflective surface are arranged with the surface of the transparent plate as a horizontal projection plane. A reverse reflection plate characterized in that the areas of the light incident surface and the reflection surface are approximately equal when projected vertically, and the contours of the two surfaces are different from each other. 16. The reflecting plate according to claim 15, wherein the front surface of the transparent plate is almost completely covered by the light incident surface. 17. The reflective plate according to claim 15 or 16, wherein the rear surface of the transparent plate is almost completely covered by the reflective surface. 18. The reflecting plate according to any one of claims 15 to 17, wherein the plurality of light entrance surfaces are formed of light entrance surfaces of different shapes having different radii of curvature. 19. The reflector according to claim 18, wherein the plurality of light entrance surfaces are comprised of two types of light entrance surfaces. 20. The reflecting plate according to any one of claims 15 to 19, wherein the outline of the light incident surface is hexagonal, square, or rectangular. 21. The reflective plate according to any one of claims 15 to 20, wherein the reflective surface has a rectangular outline. 22 Claim 15, characterized in that the corners of the outer shape of the reflective surface are rounded off.
22. The reflector according to any one of Items 21 to 21. 23. Claims 15 to 2, characterized in that the optical axes of the light incident surface and the reflective surface are inclined with respect to a direction perpendicular to the surface of the transparent plate.
The reflector plate according to any one of item 2. 24. The reflective plate according to any one of claims 15 to 23, wherein the transparent plate is a plastic plate or a plastic sheet.