JPH0230001B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention consists of a transparent material and outside the area of the apex of the reflector, the light rays incident from one light source into the material of the reflector face the light source and form a concave surface. The radiation is emitted again by a total internal reflection prism formed as a triangular ring-shaped prism which is arranged on the side and is located rotationally symmetrically with respect to the optical axis, the first of the three boundary surfaces of the ring-shaped prism being It is formed approximately cylindrical with respect to the optical axis of the reflector, the second boundary surface being formed by the rear surface of the parabolic reflector outside the range of the apex, and the third boundary surface outside the range of the apex. Relating in particular to vehicle lights and floodlights, the boundary surface of is formed approximately parallel to the light ray coming from the light source and thus forms part of the mantle surface of a truncated cone whose apex is located approximately at the center of the light source.

A reflector having an unplated surface as described above is known from DE 28 19 539 A1. This known reflector possesses a cutout in the region of its apex at an angle of approximately 90° to the center of the light source, through which an incandescent lamp serving as a light axis can be inserted. There is. Another lamp shown in the printed literature possesses a reflective section that accommodates an area of about 90° and is provided for screw mounting, with the incandescent lamp being inserted through the apex area. Not done. This reflector has prismatic protrusions on the outer surface of the reflector rather than on the inner surface.

In the reflector mentioned at the beginning, if it is necessary to form the apex range so that it reflects in the same way,
Adopting a shape of the reflecting prism located outside the apex area causes large losses in the apex area, since the light rays narrowly impinge on the prism surface running parallel to the axis. Therefore, in this range, it is necessary to apply reflective plating to the reflective mirror.

The object of the invention is to provide a reflector of the type mentioned at the outset,
It is to be formed so that there is no need for plating even in the range of the vertices.

The above objects are achieved by the present invention as follows. That is, in the range of the vertices, the second boundary surfaces running towards the vertices sandwich an apex angle of about 90° from each other,
The vertices then span a solid angle, which solid angle is approximately 30° to 60°, and the apex of this solid angle is located at the focal point or at the center of the optical axis. Since a total reflection prism is a ring-shaped prism, the surface forming the back of the reflecting mirror of such a ring-shaped prism is nothing but the outer surface of a truncated cone whose apex angle is 90° (this The apex of the conical apex angle is far away from the light source.Therefore, in this range the reflector no longer has the form of a parabola of revolution, but of a cone.In this surprisingly simple way, the reflector can be The range of the apex can also be used advantageously.In this case, the angle of the ring-shaped prism provided in the range of the apex viewed from the light source is the same as that when the shape of the prism outside the range of the apex is extended to the range of the apex. The reflector is also formed as a rotating body in the area of its apex and can be formed using easily manufactured tools from inexpensive materials.

The material used to construct the mirror must be transparent and provide total internal reflection where the light rays strike the second interface. In the area in front of the reflector, ie from the aperture to the focal plane or the center of the light source, it is possible to use any known transparent synthetic material. This is because the refractive index of these materials is at least about 1.5. rear range,
That is, in the part of the reflector that follows the front range and reaches the apex, the transparent material used here has a refractive index of at least more than 1.5, e.g.
= 1.586 polycarbonate (PC) is used. Polystyrene (PS) with a refractive index n=1.59 can also be used with good results. Similarly, styrene acrylonitrile (SAN) with a refractive index n=1.567 is also a suitable material. The same applies to epoxy resins with refractive index n=1.55 to 1.61. It turns out that glass can also be used in the same way. The selection of the material, as well as the selection of the height of the ring-shaped prism or the width of the prismatic ring, takes into account the considerations of the designer as well as the suitability and the conditions of total internal reflection that must be maintained. It is determined by

In a further advantageous embodiment, the third boundary surface of the annular prism in the region of the apex is convexly curved. In this case, the entire area of the apex of the reflector is formed by a single total reflection prism, which has the shape of a cone with an apex angle of 90°, and the base of the cone is a convex spherical cutout. There is. However, in such embodiments, the height of the prism steps in the region of the apex is very large compared to the height of the prism steps in the rear or front parts of the reflector, so that in many cases Undesirable large clumps of material result. Therefore, the range of the apex is generally divided into approximately equal step heights.

In an advantageous embodiment of the invention, the second boundary surface of the ring-shaped prism in the area of the apex, ie the surface behind it, is curved convexly with respect to the optical axis of the reflector and the third boundary surface is plane. It's getting old.
This embodiment has the feature that a large portion of the ray is reflected from the area of the vertices. This is because the portion of the ray that is incident on the second interface is all reflected and, after the first total reflection, hits the third interface of the adjacent ring prism, which is closer to the optical axis, at an unfavorable angle. No part of the light beam is lost. At this time, it should be noted that total internal reflection occurs twice in the range of the apex.

The size of the apex area depends on the material used for the rear reflector section or the refractive index of the material used here. A range of vertices forming a solid angle of up to about 60° is advantageous, with the apex of the solid angle being located approximately at the center (focal point) of the light source. In this case, although the second boundary surface is a convex surface and the third boundary surface is a flat surface, the solid angle is limited to about 40 degrees.

BRIEF DESCRIPTION OF THE DRAWINGS Further details and embodiments of the invention will be found in connection with the description of the embodiments illustrated in the accompanying drawings and in the claims.

The reflector 1, which is represented as a half section in FIG. 1, includes a front part 2, a rear part 3 and an apex part 4, which are not shown in detail in FIG. An optical axis 6 of the reflecting mirror passes through the center of the apex portion 4, and this optical axis serves as the axis of rotational symmetry of the reflecting mirror 1. A focal point 7 is also located on the optical axis 6, a light source is placed at this focal point, and the light from this light source is emitted from the reflecting mirror substantially parallel to the optical axis. The reflector 1 consists, outside the apex area 4, of a number of ring-shaped prisms 8, which are rotationally symmetrical about the optical axis 6 and which in each case intersect with each other in a narrowed part 9. Adjacent, the parts achieve a mechanical connection. The ring-shaped prism 8 is a total reflection prism with a triangular cross section and has three boundary surfaces. That is, it has a first boundary surface 10, a second boundary surface 11, and a third boundary surface 12. The first boundary surface 10 of all ring-shaped prisms 8 is a cylindrical jacket surface and is coaxial with the optical axis 6. The reason for manufacturing the conical surface, which is slightly changed from the cylindrical outer surface, is due to manufacturing reasons (this can be done by allowing the mold to come out). The second boundary surfaces 11 forming a surface together have a form approximating a rotating parabola surface, which parabola may be approximated by individual straight sections, which straight sections are connected by narrow connections. From part 9 a narrow connecting part 9 is reached, which is at the level of the steps of the individual ring prisms 8.A third boundary surface 12 is formed in the front part 2 and in the rear part 3 of the reflector. It is a plane obtained by slicing the outer surface of a cone, in which case the vertices of the cone are each located at the center point of the light source (light emitting point 7).At the boundary between the front part 2 and the rear part 3 of the reflector, there is a The third boundary surface 12 is a plane perpendicular to the optical axis 6, and the optical axis 6 intersects at the position of the focal point 7. Forming the third boundary surface as described above has the following characteristics. That is, the boundary surface formed in this way has the characteristic that there is no loss of light rays due to the interruption of the light rays. This is because they collide at an angle of inclination.First boundary surface 1
The angle of incidence of the ray at 0 and the corresponding inclination of the second interface 11 are determined by the desired refraction, as well as the two times of refraction when the light enters the ring prism 8 and when the light exits the ring prism 8. 2 and 3, the situation is shown in detail in FIGS. 2 and 3.

In the reflector 1, half of which is shown in FIG. It can be inserted from the front side of the mirror, the filament of which is placed at the focal point 7, when the rays 13 and 14 emitted from the light source become rays 15 and 16 after total internal reflection, parallel to the optical axis. move away from the reflector. Rays 15 and 16
When one wants to converge or diverge, it is sufficient to shift the light source from the focal point 7 to one side or the other along the optical axis. It is then expedient to vary the inclination or the angle of the cone of the third boundary surface 12 in an appropriate manner. When trying to converge or diverge all or a part of the light ray, this can also be achieved by curving the boundary surface or changing the inclination of the boundary surface with respect to the optical axis 6. The boundary surface 11 no longer follows the link of the approximate parabolic line.

The vertex range 4 acts as a reflective surface of the reflector. In order to prevent too large a loss of light from occurring, the shape of the ring prism must be modified as follows. That is, the second boundary surface is no longer along the link of the parabolic line, but around
They are sandwiched by a 90° apex angle. Figures 4 to 6 show a ring-shaped prism 18 adapted for the apex region 4. FIGS. The second boundary surface 11' of the ring-shaped prism 18 forms a conical jacket surface with a cone angle of 90 DEG in the region 4 of the apex. The first interface 10 is a cylindrical jacket surface. The third boundary surface 12' is curved in the shape of a lens. The third boundary surface 12' of each ring-shaped prism 18 is
As is clear from FIG. 4, it forms a kind of stepped lens or Fresnel lens. vertex range 4
According to this figure, encompasses a solid angle of 50°, the apex of which is located at the focal point 7 (FIG. 4).

As is clear from FIG. 4, in the embodiment shown in this figure, certain ranges of the light emitted from the light source are blocked, and these ranges are each indicated by a line. The curvature of the third boundary surface 12' is selected so that the light beam incident on the ring prism 18 becomes parallel to the optical axis and, after being totally reflected at the boundary surface 11', proceeds parallel to the optical axis. However, the light in the beam range 19 is thereby blocked. That is, after being totally reflected, the light beam impinges on the third boundary surface 12' of the ring-shaped prism 18 adjacent to the inside. Furthermore, the light in the beam range 20 is also blocked. That is, the light beam is the light that is incident on the first boundary surface 10. Although the loss of light belonging to the beam range 20 is unavoidable, the loss of the light belonging to the beam range 19 can be avoided in the following manner. This can be avoided by forming the third boundary surface 12'' as a plane perpendicular to the optical axis 6 in the range of the apex according to the arrangement shown in FIG. On the other hand, the second boundary surface 11'' is formed in a curved manner so as to be located radially. The maximum diameter of the ring-shaped prism 18 in the region of the apex connecting to the rear part 3 of the reflector remains unchanged compared to that shown in FIG.

In the arrangement shown in FIGS. 4 and 5, the light rays entering from the focal point 7 are projected towards the focal point. The light emitted from the area of the apex of the reflector thus forms a slightly diverging bundle of rays.

Only one conical prism 2 covers the entire vertex range 4
1, in which the first boundary surface 10 is only absent compared to the arrangement shown in FIG. The cone angle is 90° as before and two total reflections take place at the second interface 11'. Various selections are possible for the curvature of the third boundary surface 12'. Thus, for example, it is possible to choose whether the reflected light rays are reflected parallel to the optical axis 6 or through the focal point.

[Brief explanation of drawings]

Figure 1 is an axial sectional view of a reflector with an aperture in the region of its apex, Figure 2 is an enlarged detailed view of the part shown in Figure 1, and Figure 3 is an enlarged view of the part shown in Figure 1. 4 is an enlarged sectional view of an embodiment of the apex range of the reflector, FIG. 5 is an enlarged sectional view of another embodiment of the apex range of the reflector, and FIG. 6 is an enlarged sectional view of the apex range of the reflector. Figure 3 is an enlarged cross-sectional view of a third embodiment of the scope, showing that only one conical prism is used in this embodiment; In the figure, 1...Reflector, 4...Apex range, 6...Optical axis, 7...Focal point, 8, 18, 18'...Total reflection prism, 10...First boundary surface, 11, 11′,
11″... second boundary surface, 12, 12', 12″...
…This is the third boundary surface.

Claims (1)

[Claims] 1. Made of a transparent material and outside the area of the apex of the reflector, a light ray incident from one light source into the interior of the reflective material is provided on an inner surface facing the light source and which is concave; It is emitted again by a total reflection prism formed as a triangular ring-shaped prism located rotationally symmetrically with respect to the optical axis, the first of the three interfaces of the ring-shaped prism 1
0 is formed approximately cylindrical with respect to the optical axis 6 of the reflector, and the second boundary surface 11 is formed by the rear surface of the rotating parabolic line surface reflector outside the apex range 4;
And outside the range 4 of the apex, the third boundary surface 12 is formed approximately parallel to the light ray coming from the light source (focal point 7), so that the apex is approximately at the center point of the light source (focal point 7).
In reflectors, in particular for vehicle lights and floodlights, which form part of the mantle surface of a truncated cone located in the area 4 of the apex is closed and in the area 4 of the apex there is a rotating parapet line reflector. The second boundary surfaces 11' and 11'' connected to the rear surface and running to the apex form the outer surface of a cone or a surface of revolution approximating this, sandwiching an apex angle of approximately 90° from each other. The axis of rotational symmetry of this second interface then coincides with the axis of symmetry of the parabola of rotation, and the range of vertices encompasses a solid angle of about 30° to 60° with respect to the center of the focal point or light source. , the apex of the cone angle is located at the focal point or the center of the light source, and inside the cone there are first, second, and second prisms that correspond to the boundary surfaces of the ring-shaped prism provided outside the range of the apex. A plurality of ring-shaped prisms 18, 18' having three interfaces are provided,
A reflector characterized by ending in one small cone located at the apex. 2 Ring-shaped prism 18 in vertex range 4
Reflector according to claim 1, characterized in that the second boundary surface (11') forms the outer surface of a cone and the third boundary surface (12') is convexly curved. 3 Ring-shaped prism 1 in vertex range 4
2. Reflector according to claim 1, characterized in that the second boundary surface 11'' of 8' is convexly curved and the third boundary surface 12'' is flat.