Combined Lens And Reflector

Abstract

A combined lens and reflector comprising a body of light transmitting material having an outer surface and an inner surface. The inner surface is formed of a plurality of spaced cubic prisms separated by flat areas. Each prism comprises three surfaces intersecting one another to form a cube corner, the lines of intersection of said surfaces extending to a base having six sides comprising alternating long and short sides with each line of intersection extending and intersecting a short side intermediate its ends. A method of making a combined lens and reflector is disclosed wherein a plurality of reflector pins having cubic ends are assembled together, an electroform is formed to produce a body having recesses each of which comprises a cubic shape. The electroform is then machined so that the bases of the recesses define hexagonal shapes having surfaces lying in a common plane. The lines of intersection of the cubic recesses intersect the short sides of the bases.

Description

This invention relates to a combined lens and reflector and to a method and apparatus for making such a combined lens and reflector.

BACKGROUND OF THE INVENTION

Reflectors utilizing cube corner prisms are well known in the art and are frequently used to reflect light back to the eyes of an observer for signaling and safety purposes. It has heretofore been suggested that the prisms which are part of such a reflector be spaced in the body of the reflector to form a combined lens and reflector so that a light source can be positioned adjacent the interior behind the prisms with the light from the source passing through the areas between the prisms while the prisms will reflect light from the exterior.

Among the objects of the invention are to provide a novel combined lens and reflector as well as a novel method and apparatus for making the same.

SUMMARY OF THE INVENTION

In accordance with the invention a combined lens and reflector is provided comprising a body of light transmitting material having an outer surface and an inner surface. The inner surface is formed of a plurality of spaced cubic prisms separated by flat areas. Each prism comprises three surfaces intersecting one another to form a cube corner, the lines of intersection extending to a base having six sides comprising alternating long and short sides with each line of intersection of said surfaces extending and intersecting a short side intermediate its ends. In accordance with the method embodying the invention a plurality of reflector pins having cubic ends are assembled together, an electroform is formed to produce a body having recesses each of which comprises a cubic shape. The electroform is then machined so that the bases of the recesses define hexagonal shapes having surfaces lying in a common plane. The lines of intersection of the cubic recesses intersect the short sides of the bases.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view showing a bundle of pins assembled in one of the steps of the novel method of making the apparatus embodying the invention.

FIG. 2 shows a further step wherein an electroform is formed on the pin bundle.

FIG. 3 shows a further step wherein the surface of the electroform is machined or ground to form the final mold.

FIG. 4 shows in partly diagrammatic form the molding of the plastic part on the mold.

FIG. 5 is a sectional view through a combined lens and reflector embodying the invention.

FIG. 6 is a plan view of the electroform shown in FIG. 2.

FIG. 7 is a plan view of the electroform shown in FIG. 3 after machining.

FIG. 8 is a plan view of a modified form of mold.

FIG. 9 is a plan view of a further modified form of mold.

FIG. 10 is a plan view of the end of a pin utilized in the bundle shown in FIG. 1.

FIG. 11 is a view similar to FIG. 8 on an enlarged scale showing the partially completed mold.

FIG. 12 is a view similar to FIG. 9 on an enlarged scale showing the partially completed mold.

DESCRIPTION

Referring to FIG. 1, in accordance with the invention a plurality of pins such as shown in FIG. 10 are utilized and combined to make a bundle which is preferably assembled in accordance with the teachings of Hedgewick et al. U.S. Pat. No. 3,258,840 but may be also clamped. Each pin comprises a hexagonal body 10 with a cubic end defined by surfaces 11 that intersect upon lines 12, 13 and 14 which in turn intersect the sides 15.

An electroform 16 is then formed over the cubic ends by electroplating to define an intermediate or partially formed mold in which there are a plurality of cubic recesses 17 in one surface 18 thereof, each recess having a symmetrical hexagonal base (FIG. 6). Surface 18 is then ground uniformly as by a grinding wheel 19 to provide a flat plane 20. The effect of this operation is to remove material at the base of each recess 17 (FIG. 7). The exact configuration of the area surrounding each base depends on the manner in which the pins 10 are assembled in the bundle.

Referring to FIG. 6, which is a bottom plan view of the intermediate or partially formed mold 16, it can be seen that the pins 10 were assembled in the bundle in such a manner that adjacent rows 21, 22 have their lines of intersection 23, 24, 25 parallel to one another and extending in the same direction. Accordingly when the intermediate electroformed mold is subjected to the machining operation, the base of each recess 17 takes on a configuration that has six alternating short and long sides. Furthermore, the long side of one recess 17 is parallel to a short side of an adjacent recess 17. By this arrangement a flat area is provided around each recess. The width of the space or area of surface 20 between the opposed long and short sides of adjacent recesses is equal.

In accordance with the invention, the resultant finished electroform mold 16a is placed in a two part closed mold as an insert and plastic is injected to form the transparent body 25 shown in FIG. 5 which comprises cubic prisms 26 and intervening flat surfaces 27, the prism 26 being formed by the recesses 17 while the flat surfaces are formed by the intervening areas 20 defined by the bases of recesses 17.

Referring to the form of the invention shown in FIG. 8, when the pins 10 of the bundle are assembled so that alternate rows of pins have corresponding lines of intersection extending in the same direction and adjacent rows have corresponding lines of intersection extending in opposite directions, an electroform or intermediate partly complete mold 30 is formed on the bundle. When intermediate mold 30 is machined, the resultant mold 30a takes on the configuration such as shown in FIG. 8 wherein recesses 31, 32 in adjacent rows have the two corresponding lines of intersection 33, 34 extending in opposite directions and parallel to one another and a third line 35 of intersection parallel and extending in the opposite direction of the corresponding line in the recess in an adjacent row of intersection of each recess.

FIG. 11 is an enlarged view of the electroform from which the mold of FIG. 8 is made showing the electroform prior to machining on the right and after machining on the left. After machining, each recess has portions of four sides of the base thereof machined away leaving two sides intact to define six lines or sides and four flat spaces or areas around each recess. Each recess has short sides 36, 37 of each recess aligned with the corresponding short sides 37, 36 of a recess in an adjacent row. The other short side 38 of each recess is parallel to and spaced from a long side 39 of an adjacent recess in the same row. Two long sides 41, 42 of each recess are spaced from and parallel to corresponding long sides 42, 41 of a recess in an adjacent row. The width of the area 43 between the long sides of recesses in the adjacent rows is greater than the width of the area 44 where a long side 39 and a short side 38 are parallel to one another.

As in the previous form of the invention, when plastic material is molded against the mold 30, a plurality of cubic prisms are formed with hexagonal bases having alternately short and long sides and with flat areas between rows of corresponding prisms. As shown in FIG. 8, the flat areas corresponding to areas 43, 44 would comprise sinuous flat areas of alternating narrow and wide widths.

When the pins 10 are assembled in a different fashion, namely, in groups with a central pin and six peripheral pins surrounding the central pin, the intermediate mold 50 is as shown in FIG. 12 wherein with two lines 51, 52 of intersection of the recesses parallel to one another while the third line 53 of intersection extends radially. When the resultant electroform formed thereon is machined in accordance with the invention, the resultant mold 54 assumes the configuration shown in FIG. 9. Referring to FIG. 12 which is a fragmentary enlarged view of the electroform used in making the mold in FIG. 9, which shows the electroform prior to machining on the right and after machining on the left, each central recess 55 has a hexagonal base with alternate short and long sides. Alternating peripheral prisms have a long side parallel to a long side 57 and a short side 59 of a central recess. The resultant mold 40 has a continuous area of wide width 59 and narrow width 60 surrounding each central prism. The width of the area is greater where the base of the central recess is parallel to the base of a peripheral recess as at 59 and narrow where the narrow side of the central recess is parallel to the long side of a peripheral recess as at 60.

When the resultant lens and reflector is molded on a mold of mold 40, a plurality of prisms are provided which are in groups with a certain prism surrounded by a flat area and a plurality of peripheral prisms surrounding the flat area, the area surrounding the central prism having alternate wide and narrow widths.

Claims

I claim:

1. A combined lens and reflector comprising:

a body of light-transmitting material having an outer surface and an inner surface,

said inner surface having a plurality of spaced cubic prisms thereon,

each said prism comprising three surfaces intersecting one another to form a cube corner,

with lines of intersection extending to a base having six sides comprising three long sides long sides connected by three short sides,

each line of intersection extending and intersecting a short side intermediate its end,

the sides of the bases of at least some of said prisms being spaced from one another,

whereby light may be transmitted freely through the areas of said body between said prisms and light directed against said outer surface and contacting said prisms is redirected outwardly by reflection from the surfaces of said prisms.

2. The combination set forth in claim 1 wherein the areas between said prisms comprise flat surfaces.

3. The combination set forth in claim 1 wherein said prisms are uniformly spaced over said inner surface.

4. The combination set forth in claim 1 wherein said prisms are arranged in rows, adjacent prisms in any row have a long side of said base parallel to a short side.

5. The combination set forth in claim 4 wherein corresponding lines of intersection of prisms in adjacent rows are parallel to one another.

6. The combination set forth in claim 4 wherein the long side of the base of one prism is provided adjacent the short side of a base of a corresponding adjacent prism throughout the inner surface.

7. The combination set forth in claim 4 wherein the distance between the bases of adjacent surfaces is substantially equal throughout.

8. The combination set forth in claim 4 wherein the corresponding lines of intersection of alternate rows of prisms are parallel to one another.

9. The combination set forth in claim 4 wherein the corresponding lines of adjacent rows of prisms are such that one line of intersection is parallel to a corresponding line but extends in an opposite direction,

another line of intersection is parallel and extends in opposite direction.

10. The combination set forth in claim 1 wherein the short side of the base of one prism is parallel to the long side of the base of an adjacent prism,

said one prism having another long side of the base thereof parallel to the long side,

each said prism having a long side of the base thereof extending along a corresponding long side of an adjacent prism,

each said prism having two short sides thereof extending along two short sides of a base of adjacent prisms whereby flat areas are provided between adjacent long sides having a greater width than the flat areas provided between adjacent long and short sides.

11. The combination set forth in claim 1 wherein said prisms are provided in groups along said inner surface,

each said group comprising a central prism and six peripheral prisms,

the peripheral prisms having two lines of intersection thereof aligned with corresponding lines of the adjacent prisms circumferentially and the other line of intersection thereof extending outwardly therefrom whereby alternate peripheral prisms have a long base adjacent a long base of said central prism and alternate peripheral prisms have a long base adjacent a short side of the base of the central prism.