JPS585405B2 - Saiki Hanshiyaki Oyobi Sono Seikeiyo Kanegata - Google Patents

Description

[Detailed description of the invention] The present invention relates to a retroreflector that retroreflects external light.

The present invention also relates to a mold for forming the retroreflector.

The retroreflector technology has the following problems.

B. In conventional retroreflectors, if the direction of incidence of external light deviates even slightly from the normal direction of the outer surface, the reflection performance deteriorates significantly.

In particular, if the angle is deviated by 20 degrees or more, the reflection performance will be extremely degraded and it cannot be used effectively.

In order to solve the above-mentioned problem, if the reflective element is configured to be tilted, a stepped portion will occur in the element due to problems in mold formation, which will create a reflective ineffective portion and reduce the reflective performance.

Furthermore, in order to ensure the amount of light that is reflected and diffused in the vertical direction, conventional retroreflectors must have a large area as a whole.

The present invention aims to eliminate the above-mentioned problems, but first, the above-mentioned problems will be described in more detail.

First, point A above will be explained.

What is shown in FIGS. 1 to 3 are reflective element units used in conventional retroreflectors that are commonly used.

This retroreflector has a flat outer surface on which external light enters, and
and an inner surface formed with a plurality of reflective element units.

Each reflective element unit has a rectangular outline when viewed from the direction perpendicular to the outer surface, and is made up of two reflective elements I and I that are closely arranged with each other and are symmetrically arranged with each other. It has become.

Each reflective element is composed of three planes that intersect perpendicularly to each other, and the same angle (36° 16'
) is configured so that the straight line forming the line is perpendicular to the outer surface.

In addition, the vertices 1 and 2 of each reflective element are located at the center of the rectangular outline of the reflective element, and one ridgeline 1, 3, 2
- 4 is located on the perpendicular bisector of the short side of the rectangular outline of the unit.

In general, among the rays of light that are incident on three mutually perpendicular surfaces, the number of rays that are emitted as retroreflected rays is 1.
A ray of light that is incident on one surface at an angle of total reflection, then totally reflected on another surface and exits, or at an angle such that it is totally reflected on another surface and exits.

That is, the area of the effective reflective surface of each reflective element varies depending on the incident angle of the external light ray, and the reflection performance, which is proportional to the area of the effective reflective surface, also changes as the incident angle of the external light ray changes.

For example, in the above-mentioned conventional reflector, if the refractive index of the material is 1.5, each reflective element unit for parallel light incident at an angle of θ215° in the horizontal direction with respect to the normal to the outer surface. The effective reflecting surfaces of the reflector are the quadrilateral abed and the hexagon efghij, as shown in FIG. 4, and the reflection performance of the entire reflector can be understood as being proportional to the sum of these areas.

The table shown in FIG. 5 shows changes in the effective reflection surface of each reflection element unit when the incident angle θ is varied.

The figure only shows the case where the angle of incidence changes horizontally to the right, but when the angle of incidence changes to the left, the area change of the effective reflective surface of the reflective element ■ changes to the right. Equal to the area change of the reflective element ■ at time,
The change in area of the effective reflective surface of reflective element (2) is equal to the change in area of reflective element I when the angle changes to the right.

As shown in the figure, when the incident angle θ becomes 19°36' or more, the surface of one of the reflective elements no longer constitutes a total reflection surface, and the effective reflection area becomes rapidly small.

For this reason, the reflection performance of the entire reflector also sharply declines at θ=19°36'.

If the relationship between this angle of incidence θ and the reflection performance of the entire reflector were drawn as a graph, it would look like the line I+■ in FIG.

This graph shows the reflection performance when θ=0° as 100.

As is clear from this graph, the reflection performance of the above-mentioned conventional reflector decreases significantly if the direction of incidence of external light deviates from the normal direction of the outer surface, especially if it deviates by more than 20 degrees. has the characteristic that reflection performance is extremely reduced.

This kind of reflector can be used when the direction of incidence of external light is always approximately constant, but when attached to something that swings a lot, such as a bicycle or a buoy on the sea,
It cannot fully fulfill its role as a signaling device.

For this reason, it may be possible to achieve effective reflection by providing a tilted element portion whose optical axis is tilted at a certain angle with respect to the outer surface.

However, if the element is simply tilted, a problem arises in that a step portion is generated and an ineffective reflection portion is formed.

In other words, the aforementioned problems arise.

That is, if the element is simply tilted, a step S will inevitably occur when the mold M is obtained from the molding pin P, as shown in FIG.

As a result, the molded reflective element E also has a stepped portion S' as shown in FIG.

Therefore, the width t in the figure becomes the invalid reflection range due to the stepped portion S'.

That is, light that is incident on this portion, or light that is incident on this portion after being incident on another surface and reflected, is not reflected effectively and the reflection performance becomes low.

For example, FIG. 25 shows a case where the element is tilted left and right. In this case, as shown in FIG. (A portion where the light incident on the other surface is invalidated by the stepped portion S'.

(shown with fine dots) occurs.

Figure 27 shows the case where the element is vertically inclined;
A reflection-ineffective area as shown in the figure is generated.

(In each figure, ft0 is the inclination of the element, a is the dimension of the element, b,
c indicates the dimension of the step, X, Y, Z are coordinate axes, d, e.

o, o', α' indicate point positions.

FIG. 25 shows the front shape and one side cross section, and FIG. 27 shows the front shape and two side cross sections).

In this way, the idea of simply tilting the element causes a problem in the fabrication of the mold and a reduction in reflection performance.

Next, we will discuss the problems in the above-mentioned vertical reflection and diffusion.

Normal road traffic signal devices retroreflect the vehicle's light beam to inform the driver of the vehicle of the presence of obstacles, etc., but the light source of the vehicle and the driver's viewpoint are shown in Figure 13. As shown, it is normal that they are shifted in the vertical direction.

Therefore, in such a retroreflector, among the retroreflected light rays, the light rays that are diffused upward due to optical errors etc. act as useful signal light.

Therefore, in the conventional example, in order to secure such upwardly diffused light and maintain effective reflection performance, the area of the reflector must be made relatively large.

In view of the above circumstances, the present invention has the following features: (1) Even if the incident angle of external light rays changes, there is little deterioration in reflection performance, and therefore, it has wide-range reflection performance, and can be effectively used even when attached to an object that constantly swings greatly. (11) It is an object of the present invention to obtain a retroreflector that has a large vertical diffusing ability and therefore can obtain desired reflection performance without increasing the reflector area so much, and (111) such a retroreflector. Another object of the present invention is to relatively easily obtain a mold that can produce a reflector without tilting the element and therefore without creating a stepped portion in the element.

Illustrated in FIGS. 6 and 7 is one embodiment of a retroreflector according to the present invention.

This retroreflector has a flat outer surface on the lower side of FIG. 7 and an inner surface formed with a plurality of reflective element units on the upper side.

As shown in FIG. 6, each reflective element unit has a rectangular shape when viewed from a direction perpendicular to the outer surface, and is closely arranged.

FIGS. 8 to 10 are enlarged views of the reflective element units described above, and each reflective element unit consists of two mutually congruent reflective elements (1) and (2).

Each reflective element 111. V is composed of three planes that intersect perpendicularly to each other.

In other words, the reflective element ■ has a pentagonal surface 5 in FIG.
16, 17, 18, 19, and the same square surface 5.
It consists of three sides: 6, 8, and 19, and 5, 6, 9, and 16.

Similarly, reflective element ■ has pentagonal surfaces 1, 20, 21, and 22.
・23, square faces 7, 6, 8, 23, faces 7, 6, 9
・Consists of 20 three sides.

When viewed from the direction perpendicular to the outer surface, one of the three ridgelines 5, 6, 7, and 6 formed by these surfaces forms the boundary between both reflective elements I and I as shown in Fig. 8. It is configured to be a perpendicular bisector of lines 8 and 9.

Also, the same angle (36°
16') is a direct fit (so-called element axis) that is 54 in the left direction in FIG.
It is tilted by °44'-φ=12°28'.

Both reflective elements I and I are symmetrical to each other with respect to a plane perpendicular to the outer surface including boundaries 8 and 9 (that is, a plane including 8 and 9 in Fig. 8 and perpendicular to the long plane on which Fig. 8 is drawn). It becomes.

In this example, the refractive index of the material is 1.5.

In this example, the slope of 54°44'-φ=12°28' was adopted as an example of designing a reflector with the widest angle, that is, a reflector that reflects at the widest angle of incidence. This is what is shown.

The table in FIG. 11 shows the change in the effective reflection surface when the incident angle θ changes in the reflection element (2).

As is clear from this table, the area of the effective reflecting surface is maximum when φ = 18°54' (rightward), gradually decreases as θ increases to the right, and gradually decreases as θ decreases, and then θ
The critical point is reached at =30' (leftward).

Changes in the area of the effective reflective surface of reflective element (2) are expressed as a table obtained by translating the table of FIG. 11 symmetrically around θ=0°.

Therefore, if this reflective element unit is used to create a reflector with the same area as the reflector using the known reflective element unit shown in FIGS. 1 to 5, its reflection performance will be the first.
This results in a change as shown by the line I+I in FIG.

As is clear from this graph, according to this reflector,
Even if the incident angle θ deviates from the normal to the outer surface by 20° or more, the reflection performance does not suddenly deteriorate.

The absolute amount of reflected light is smaller than that of the known reflector in the range of 30 degrees below θ, but if this is a problem, it can be solved by increasing the area of the entire reflector.

Further, by changing the inclination angle 54°44'-φ with respect to the normal line of a straight line forming the same angle to the three surfaces of each reflective element, the reflective performance characteristics can be adjusted to some extent.

Moreover, according to this reflector, since the entire surface of the reflector reflects almost uniformly, visibility is excellent.

This reflector can exhibit even better visibility when used as a road traffic signal device.

In other words, as mentioned above, normal road traffic signal devices retroreflect the light rays from the vehicle to notify the driver of the vehicle of the presence of obstacles, etc., but the light source of the vehicle and the driver's viewpoint Usually, they are shifted in the vertical direction as shown in FIG.

Therefore, in such a retroreflector, among the retroreflected light rays, the light rays that are diffused upward due to optical errors etc. act as useful signal light.

In general, when a reflective element is composed of three mutually perpendicular surfaces, if each reflective surface is divided into two parts by extending the three ridge lines, then the light incident on a certain reflective surface part can be divided into two parts. After the light rays are reflected by other adjacent reflecting surfaces, they are reflected by opposing reflecting surfaces with the apex as the center, and then emitted. Surface part 5, 10, 8, 11, 12, 5.
Since the portions 13, 9, 14, and 15 are larger than the other reflective surface portions, the amount of reflected light that is diffused in the vertical direction is relatively large, as shown in FIG.

Therefore, in practical use, this reflector can exhibit reflection performance comparable to conventional reflectors even in the range of θ<30° without significantly increasing the area of the entire reflector.

The line I'+V' in Fig. 15 shows how the area of the effective reflective surface portions located above and below the apex of this reflective element unit changes with changes in θ, which is calculated by dividing the area by 3/3 of the area of the reflective element unit. It is shown with 1 as 100.

This graph also confirms that the reflection performance in practical use, which is diffused in the vertical direction, is excellent.

16 to 21 show two types of pins 31, 32 that constitute a mold for molding the inner surface of the reflector described above.

These pins 31 and 32 have a hexagonal horizontal cross-sectional shape, and have two planes of symmetry that intersect perpendicularly to each other on the central axis.

The horizontal cross-sectional shape of these two types of hexagonal pins 31 and 32 is 6
Each square has opposing sides 31a and 31 of the same length.
b: 32a, 32b, and four sides 31c to 31f; 32c to 32f, which are slightly longer than the twist and have the same length.

Therefore, these two slightly long sides 31c and 31d, 31e and 3
1f; The internal angles formed by 32c and 32d, and 32e and 32f are each an angle of 2ε less than 120°.

These hexagonal pins are made into pins 31. with different tip shapes.
32, and the short sides 31a and 31 of the hexagon are
b: 32a and 32b are arranged alternately one row at a time so that they are in contact with each other to form a mold.

That is, both have the same thickness in the vertical direction, and the pins 31 arranged in a row in the vertical direction and the pins 32 arranged in a row in the vertical direction are alternately arranged closely in the horizontal direction.

As shown in FIG. 17, the first type of pin 31 among the two types of pins has two interior angle surfaces of 2ε each at (90-φ) degrees with respect to the pin axis.

These two faces intersect at the top, and the short 2nd half of the hexagon
An edge 31g is formed on the straight line connecting the midpoints of the sides.

On the other hand, in the second type of pin 32, as shown in FIGS. 20 and 21, the surfaces of the four interior angles other than the aforementioned 2ε interior angle are δ degrees with respect to the pin axis.

The four sides intersect, and the two short sides of the hexagon are 32
Edges 32g and 32h are formed on the straight line connecting the midpoints of a and 32b.

Between φ, ε, and δ mentioned above, A relationship has been established.

This is because the surface formed by the top surface of the pin 31 is AOB, the surfaces formed by the top surfaces of the two adjacent pins 32 and 32 are COD and EOF, and 0A=OB=O
C = OD = OE = OF, and if the plane passing through 0 and parallel to AB and intersecting with the plane AOB at φ degrees is the XY plane, these three planes intersect perpendicularly to each other to form a retroreflective element. To configure /AOB-/C0D-/EOF=90°
Therefore, points B and C, D and E, and F and A must each coincide.

However, since the two adjacent pins 32 and 32 are congruent with each other, and the top surface corresponding to the surface COD and the top surface corresponding to the surface EOF intersect perpendicularly at each pin, the surface COD and the top surface corresponding to the surface EOF are perpendicular to each other. The plane EOF is perpendicular to each other, and the points O and E
always match.

Therefore, in order to obtain /AOB-90°, if the midpoint of AB is M, then AM must be σM and /AMO must be 90°.

Therefore, when the projection points of points A and M on the XY plane are divided by A/ and M/, respectively, it must be 10M'A'=90, so it must be as follows.

In this way, if /AOB-90°, the surface COD
Since and plane EOF are perpendicular to each other, points A and F, B and C
match each other.

Also, in order to be /EOF-90°, the plane EOF must be
Since it intersects the Y plane at 90°-δ, AOA(F
) must intersect the XY plane at δ degrees.

Therefore, it must be.

The conditions for /C0D=90° are also similar.

In addition, in the case of this example, since φ=42°16', ε
=53°30', δ=28"24'.

The pins 31 and 32 configured in the above-mentioned manner are arranged in a vertical line and alternately arranged in the horizontal direction to form a mold.

The row of pins 31 forms a region P shown in FIG. 6, and the row of pins 32 forms a region Q.

In this way, the pins 31, 32 can be arranged to produce a mold without having to be tilted themselves.

Therefore, a step portion as described in FIG. 23 and subsequent figures does not occur, and the reflection performance of the element does not deteriorate.

Originally, in the present invention, as is clear from the above data, it is possible to achieve the same effective reflection as when the reflective element itself is tilted, even if it is not tilted.

Further, such a mold is relatively easy to manufacture.

As mentioned above, the retroreflector of the present invention has little deterioration in reflection performance even when the incident angle of external light rays changes, and therefore has wide-range reflection performance and can be effectively used even when attached to an object that constantly oscillates. At the same time, the vertical diffusion power is sufficiently large, and the desired reflection performance can be obtained without increasing the reflector area so much.

Moreover, this effect can be achieved without the need for the reflective element itself to be inclined with respect to the outer surface.

Therefore, the mold does not have a stepped portion and can be manufactured relatively easily.

[Brief explanation of drawings]

1 to 3 show a reflective element unit used in a conventional reflector, with FIG. 1 being a rear view, FIG. 2 being a right side view, and FIG. 3 being a bottom view. Figure 4 shows the shape of the effective reflective surface when the incident angle θ is -15° in the reflective element unit of Figures 1 to 3, and Figure 5 shows how the effective reflective surface changes when θ changes. It shows. 6 to 10 show an embodiment of the reflector of the present invention, FIG. 6 is a rear view, FIG. 7 is a sectional view taken along the line ■-■ in FIG.
8 is an enlarged rear view of one reflective element unit, FIG. 9 is a right side view of FIG. 8, and FIG. 10 is a bottom view of FIG. 8. Figure 11 shows the state of change i in the effective reflecting surface when the incident angle θ changes in the reflective element 1 in Figures 8 to 10.
FIG. 12 is a graph showing the reflection performance characteristics of the conventional reflector and the reflector of FIG. 5. Fig. 13 is an explanatory diagram when the retroreflector is used as a road traffic signal device, Fig. 14 is an explanatory diagram showing the diffusion pattern of the reflected light from the reflector in Fig. 6, and Fig. 15 is an explanatory diagram showing the effective vertical direction. It is a graph showing changes in a reflective surface. 16 to 21 show pins for the reflector mold of FIG. 6, FIG. 16 is a top view of the first type of pin, FIG. 17 is a front view thereof, and FIG. The figure is a top view of the second type of pin, Figure 19 is its front view, Figure 20 and
FIG. 1 is a side view of the second type of pins as viewed from a direction shifted by ε degrees from the front to the left and right. FIG. 22 is a schematic diagram of the relationship between the three surfaces formed by these pins. FIG. 23 shows a pin and a mold of a reference example, and FIGS. 24 to 28 are reference views for explaining the action of the tilting element according to the reference example. Explanation of symbols, 1. V...Reflection element, 31...
...First type of pin A32...Second type of pin.

Claims (1)

[Claims] 1. A device comprising a substantially flat outer surface on which external light is incident, and an inner surface formed with a plurality of reflective element units, each of which has a rectangular shape when viewed from a direction perpendicular to the outer surface. Each reflective element unit is composed of two reflective elements, and the first reflective element is composed of three planes that intersect perpendicularly to each other. Of the three ridgelines formed by these surfaces, one ridgeline is relative to the boundary line between the reflective element and the second reflective element of box 1 when viewed from the direction perpendicular to the outer surface. A straight line that is perpendicular and makes the same angle to the three surfaces is configured to be inclined with respect to the normal to the outer surface on a surface perpendicular to the outer surface including the one ridgeline, and a second A retroreflector, wherein the reflective element is configured to be symmetrical to the first reflective element with respect to a plane perpendicular to the outer surface including a boundary line between the reflective element and the first reflective element. 2. A mold for molding the retroreflector according to paragraph 1,
Two types of hexagonal pins are provided for forming reflective elements, and each of the two types of hexagonal pins has two opposite sides of the same length in horizontal cross-section, and a four-sided side with the same length that is slightly longer than the two opposite sides. Therefore, the interior angles formed by the two somewhat long sides are each an angle of 2ε degrees, which is less than 120 degrees, and two types of such hexagonal pins are made with different tip shapes. The first type of pins are arranged alternately in rows so that they are in contact with each other.
φ) degrees, and the two surfaces intersect at their tops to form a ridge on a straight line connecting the midpoints of the two short sides of the hexagon, and the second type of pins form the two interior angles of 2ε degrees. The other four interior angle faces are at δ degrees with respect to the pin axis, and the four faces intersect on the straight line connecting the midpoints of the two shorter sides of the hexagon and on the diagonal line of the two interior angles of 2ε. and form a ridge, φ. The mold has the following relationship between ε and δ.