US 1950560 A
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Description (OCR text may contain errors)
March 13, 1934.` A. 1 MARTINEK ET A1.
SIGNAL` Filed May 12, 1930 2 Sheets-Sheet 1 INVENYOR-S ATTORNEYJ Mw M /v m Patented Mar. 13, 1934 PATENT OFFICE SIGNAL -Alois L. Martinek and Arnold N. Taylor, Detroit,
Mich., assignors to C. M. Hall Lamp Company, Detroit, Mich., a corporation of Michigan Application May 12, 1930, Serial No. 451,745
4 Claims. (Cl. 88-1) The invention relates to light reflecting devices adapted to be illuminated from an outside source of light. More particularly the invention deals with a reector composed of a light transmitting material so constructed and arranged that part of the light striking the same is reflected back and part is transmitted therethrough.
The object of the invention is to obtain a reflector of the above described type having a conj g figuration such as to lend itself readily to inexpensive manufacturing processes. Another object of the invention is to obtain a reflector having such a configuration that it may easily be modified to obtain the desired proportion be- 1 5 tween the amount of light reflected and the amount transmitted through the same.
These and other objects are attained by providing the novel construction hereinafter set forth and illustrated in the accompanying drawings, wherein Figure 1 is a rear view of a reflector embodying our invention;
Figure 2 is an enlarged view showing the arrangement of prisms on the rear side of the re- 3 ector;
Figure 3 is a cross `on the line 3 3 of Figure 2;
Figure 4 is a view similar to Figure 2 showing a modified construction designed to reflect only a portion of the light; I
Figure 5 is a cross section on the line 5-5 of Figure 4^;
Figure 6 is a top plan view of a die or mold vfor casting the reflector illustrated in Figure 2;
Figure '7 is a sectional View of the die shown in Figure 6 taken on the line 7--7 of Figure 6. Figure 7 is illustrative also of sections taken on the line '1a-'7a and '7b-719;
Figure 8 is a section through a lamp provided with the improved reflector;v
Figure 9 is a section onrthe line 9-9 of Figure 6.
Figure 10 is a sectional view similar to Figure 7 showing the modified die for forming the modified reflector of Figure 1.
Referring now to the construction illustrated in Figures 1, 2 and 3, 10 represents the reflector section of the reflector takenv The reflector preferably has a smooth front surface ll and a prismatic rear surface 12 with a marginal portion 13 also forming a smooth surface. The roughened portion 12 which is formed preferably by casting consists of a series of indentations 14 and intermediate ridge portions 15 constructed and arranged in accordance with a predetermined geometrical pattern hereinafter set forth.
Figuresu, 7 and 9 illustrate thedie or mold for casting of the reector shown in Figure 2 and this die or mold 16 has a prismatic surface 17 comp'emenlaryto the prismatic surface 12 of the reflector. The surface 17 is formed by milling or otherwise c utting a series of parallel grooves' 18 with a cutting tool 19 adapted to form a V-shaped slot, the opposite surfaces 20 and 21 of which are substantially apart. The surface 1'7 is also provided with a series of parallel grooves 22 simillar to the grooves 18 but extending at an angle of 120 with respect to the grooves 18. A third set of parallel grooves 23 are formed in the same manner at an angle of 120 with respect to the grooves Y22 and 18, respectively. This arrangement forms in the prismatic surface 17 a series of pyramids 24,'each having its apex in a common plane and each havinga triangular base line in a plane parallel to the plane of the apexes. Each pyramid has three triangular faces and each face 25 is bounded by a base line 26 and two equal side lines 28, the base line being ,longer than the side lines.
The geometrical arrangement as above set forth forms the prismatic surface into a series of prismatic faces 25, each of which extends at an angle of 90 with respect to the adjacent face in the next pyramid. Thus a light ray as represented by the arrow 29 traveling perpendicular to the plane of the prismatic surface strikes a prismatic face 25 and. is reflected by said surface to an adjacent prismatic face which it strikes at an angle of 45 and is therefore reflected away from the prismatic surfacein a direction perpendicular to its plane as represented by the arrow 29a. Since the prismatic surface is entirely composed of a series of the prismatic faces all light striking the surface perpendicular to the plane thereof will be reflected back. n
Since the prismatic surface 12 of the reiiector is formed from the die or mold shown in Figure 6, the surface instead of having a series of upstanding pyramids is provided with a series of inverted pyramidal recesses 30 complementary in form to the pyramids. Therefore the appearance of the surface 12 from the rear side of the reector may be described as a series of ridges 31 arranged at angles of 60 with respect to one another. Light striking this surface from the rear side of the reflector is not appreciably reflected because of the angular arrangement of the side of the ridges. However, light striking the front surface ll of the reflector will be transmitted into the transparent material until it strikes the faces 32 defining the pyramidal recesses 30 and will thereupon be reflected back in the same manner as light striking the prismatic surface 1'? of the die. Thus as illustrated in Figure 3, a beam 33 approaching the reflector in a perpendicular direction will strike the face 32 and will be reflected to the adjacent face 32 and Will in turn be reflected by the last mentioned face in a direction parallel to the beam 331 as indicated by the arrow 34. Since the surface 12 consists entirely of the angularly arranged faces 32, all light approaching the front face of the reflector in a perpendicular direction will enter the transparent material and be reflected back. Where the material is a definite color the light reflected from the reflector will assume the same color and consequently a colored reflector will appear to be illuminated with a colored light when it is placed in the path of a beam of white light.
One of the uses of our improved reflectors is for tail lamps on vehicles and as illustrated in Figure 8, the reflector 10 is placed in a lamp casing 35 which contains also an incandescent bulb 36. The reflector thus encloses the lamp with the prismatic side l2 within the casing and the smooth side 11 exposed to view. With this construction even though the incandescent bulb is not lighted, the reflector 10 will nevertheless act as an illuminated signal whenever it is subjected to an outside source of light such, for example. as the beam from a headlamp of another vehicle. On the other hand, when the incandescent bulb 36 is lighted the reflector will also act as an illuminated signal from the light within the lamp which is transmitted through the same. The character of the prismatic surface 12 however is such that only a small portion of thel light is transmitted through the reflector and when it is desired to increase the intensity of illumination due to the incandescent bulb a modified form of reflector may be used.
In this modified form the general geometric configuration is the same as shown in Figure 2 but each of the pyramidal recesses 30 terminates before reaching the apex forming a flat triangular surface 37 substantially parallel to the surface 11. Thus the light which strikes this surface 37 instead of being reflected is transmitted directly through the glass'. The effect of this modification is to reduce the amount of illumination resultingfrom the reflection of light from outside of the lamp and to increase the amount of illumination due to the incandescent bulb within the lamp. It will be understood that the amount of total area in the triangular surfaces 37 may be predetermined with respect tothe total area of the prismatic surface in order to obtain the desired results. In order to obtain the modied prismatic surface the mold or die illustrated in Figures 6 and 7 has the apex portion of each pyramid removed as indicated by the dotted line 38, thus forming a truncated pyramid illustrated in Figure 10 with a flat top surface 39.
It is to be understood that while in the preferred embodiment of the invention the prismatic surface on the reflector is complementary to the die so that the light must pass into the glass before it is reflected back, the die itself can also act as a reflector when the light strikes the same directly. Consequently, the geometrical configuration of the die itself might be used as a reflector. Thus in the broader aspects, our invention contemplates a prismatic structure having the angular arrangement of the facets above set forth regardless of Whether this relationship provides upstanding pyramidal projections as in the die (Figures 6 and 7) or depressed pyramidal recesses as in the reflector (Figures 2 and 3).
What we claim as our invention is:
l. A reflector comprising a transparent disk having a plurality of facets grouped together into a .three-sided inverted pyramidal configuration. the facets of two adjacent inverted pyramids having an included angle of approximately 90 and the respective facets of each inverted pyramid having an included angle greater than 90.
2. A reflector comprising a transparent disk havin'g a plurality of facets grouped together into a three-sided inverted pyramidal configuration, the facets of two adjacent inverted pyramids having an included angle of approximately 90 and the facets of each inverted pyramid having an included angle of 45 with respect to the plane of the base.
3. A reflector comprising a transparent disk having a series of pyramidal recesses in one side thereof, each recess being defined by triangular facets arranged in a predetermined angular relationship, the facets .of adjacent recesses havv ing an included angle of substantially 90.
4. A lens having on one side a plurality of inverted V-shaped ridges having included angles ALOIS L. MARTINEK. ARNOLD N. TAYLOR.