US 2909857 A
Description (OCR text may contain errors)
BEO-Qthl xR- .amemasv Oct. 27, 1959 2,909,857
G. D. WILSON LIGHTING SYSTEM FOR COUNTERS AND THE LIKE Filed July 12, 1957 FIT g; 3
INVENTOR. GEORGE D. WILSON sYjl /w ATTORNEY United States Patent LIGHTING SYSTEM FOR COUNTERS AND THE LIKE George D. Wilson, Riverdale, N.Y., assignor to General Precision Laboratory Incorporated, a corporation of New York Application July 12, 1957, Serial No. 671,472
7 Claims. (Cl. 40-77) This invention relates in general to indicating instruments having an actuating shaft, and more particularly to the illumination of such instruments having drum dials, such as counters.
Proper lighting of such instruments in aircraft is particularly important, for they must be clearly visible under all ambient light conditions through very wide viewing angles, and at the same time must not exhibit exposed light sources nor emit noticeable spill or stray light. The problem is acute in counter types of instruments in which large moving cylindrical dials must be evenly illuminated. Since space is always valuable in aircraft, little increase in bulk of the indicating instrument to provide for illumination can be tolerated.
The present invention satisfies these requirements, with the only increase in bulk that due to a slight enlargement of the actuating shaft. It provides a shaft made partly or wholly of a transparent solid such as glass or an acrylic resin, and provides one or two small instrument-type lamps at one or both ends of the shaft. Thus, employing the shaft at one and the same time as a mechanical member and as a light pipe, the light is conducted to several locations within the instrument. By appropriate means light is radiated from the light pipe at each of these locations to illuminate portions of the drum dials visible in mask apertures.
It is of course obvious that this lighting system can be applied Without basic change to instruments having other than drum dials. However, the advantages of this invention are most apparent when applied to overcome objections to present systems of lighting drum dials, and particularly of counter drum dials.
One object of the present invention is to provide an improved lighting system for instruments having a shaft.
Another object of the invention is to provide an improved lighting system for instruments having a shaft and at least one drum dial.
Still another object is to provide an instrument lighting system including a revolving shaft to conduct the light.
A further understanding of this invention may be secured from the detailed description and drawings, in which:
Figure 1 depicts an embodiment of the invention including a light-conducting shaft having light-diffusing zones and a single light source.
Figure 2 depicts a light-conducting shaft having lightemitting notches and a single light source.
Figure 3 depicts a light-conducting shaft having two light sources and equal light-diffusing zones.
Referring now to Fig. 1, a counter is depicted having an actuating round shaft 11, two end plates 12 and 13 forming the ends of the enclosing frame, and three drum dials 14, 16 and 17 carrying suitable indicia. A portion of the enclosing frame forms a mask 18 containing three apertures or windows 19, 21 and 22, through which the indicia of the three dials may be viewed. The mechanism is protected by a glass cover 23 closing this invention and as the necessary construction will be apparent to those skilled in the art, further description is not believed necessary.
The cylindrical portions of the three drums 14, 16 and 17, such as the hollow cylinder 28 of drum 14, are constructed of a translucent solid material, such as an acrylic resin, upon which are inscribed appropriate opaque counter indicia. Alternatively, the indicia may be transparent, or dilfusingly translucent, and the remainder of the drum opaque. The shaft 11 is also constructed of a transparent material such as an acrylic resin. It is provided with an end stub 29 by which it may be rotated to advance the counter mechanism. The other end 31 of shaft 11 is concave, and a small lamp 32 of the instrument lamp type is provided adjacent to the concave surface of the end of the shaft. Two ball bear ings 33 and 34 support shaft 11 in the end frames 12 and 13. Three roughened circumferential belts or zones 36, 37 and 38 are provided so positioned that the center plane of each is approximately coincident with the center plane of one of the three hollow drum dials. Zone 36 is the smallest, while zone 38, furthest from the lamp 32, is larger than the others. These roughened surfaces may be constructed by sand blasting or otherwise so that at these zones the smoothness of the surface is completely destroyed. At all other parts of the surface of the shaft the surface is quite smooth, and at all other parts except at these zones and at the concave end 31 the shaft is provided with a metallic coating, such as by electroplating. The plated surface has a two-fold purpose; it provides bearing surfaces for rotating parts and pressed parts, and unwanted light emission from the shaft improving the efliciency of light transfer.
In the operation of the light system of this counter, light from lamp 32 enters the unplated concave end 31 of the acrylic resin shaft 11. This light generally cannot escape from the shaft because of the plating, and even in the absence of plating, since most of the light rays strike the smooth shaft surface at angles beyond the critical angle, they would not be able to escape. However, at the roughened and unplated zone 36 light will be emitted, somewhat more radiating generally perpendicularly to the surface than at other angles. Those rays emitted in the direction of window 19 will silhouette the opaque indicia on drum 28, thus rendering them visible. The same action occurs at zone 37, illuminating the periphery of drum dial 16, and at zone 38 illuminating dial 17. Since after some light is extracted at zone 36 less remains to be radiated from zone 37, the latter zone is made larger than zone 36. For the same reason zone 38 is larger than zone 37.
Several other constructions may be employed to extract light from the shaft in place of the roughened zone construction. For example, large, small or even microscopic circumferential grooves may be cut in the shaft at the locations of zones 36, 37 and 38 inplace of merely roughening the surface. Much of the light will then strike the grooves at less than the critical angle and since the grooves are unplated the light will be radiated out of the shaft.
A special form of such construction is depicted in Fig. 2, in which three peripheral grooves or notches 39, 41 and 42 are turned in the shaft 43. Since these grooves weaken the shaft mechanically a core 44 made of steel, nylon or other strong material is provided. Alternatively a strengthening sleeve of such strong material may be placed about the shaft. The shaft 43 is designed to be used in the counter of Fig. 1, the grooves having the same locations as the roughened zones which they replace. A lamp 32 is provided adjacent one end of the shaft, which is deeply recessed to receive it. Each of the grooves 39, 41 and 42 consists of two parts: a radial portion such as surface 42 and an oblique surface such as surface 42". All parts of the shaft are plated except the recess 46 and the radial groove surfaces.
The behavior of the shaft is as follows. Light from lamp 32 strikes the unplated radial plane surfaces of the three grooves nearly perpendicularly thereto and emerges therefrom. Much of the light will strike the oblique side of the groove which, being plated, will reflect the light. This surface should have an angle of nearly 45 or else should have a reflective mat finish to diffuse the light, for if specular much may be reflected obliquely and very little perpendicularly to the shaft.
In order to illuminate a succession of dials evenly without special proportioning of each diffusion zone, two light sources may be employed, one at each end of the shaft. Approximately equal light will then be diffused from three or more similar zones. This arrangement has the additional virtue of insuring continuity of service for, having two lamps, if one burns out the other lamp will illuminate the dial well enough to serve until the burned out lamp is replaced.
Two lamps 47 and 48 may be arnanged as shown in Fig. 3 to shine into the unplated ends 49 and 51 of an acrylic resin rod having three or more similar unplated diffus ing zones 52, 53, and 54. The remainder of the rod may be plated as before described. The rod can be driven through a gear train 56 to leave the end 51 free to receive the light of lamp 48.
In the descriptions of the light-emitting surface portions of the transparent shaft of this invention, it will be recognized that two separate properties of such portions are involved, one concerned with the light transmission property of the surface junction between solid and air, and the other concerned with the configuration or con tour of the surface as it affects light emission. The first or junction property may be characterized as opaqueness, having a matte surface, or clearness, both the clear and matte surfaces being defined as translucent or light transmitting. A great many types of the second property, contour, may be employed with good effect in different circumstances, these types of contour being characterized as smooth, non-smooth, rough, sand-blasted, corrugated, notched, grooved, ribbed and threaded contours.
What is claimed is:
1. An instrument dial illumination system comprising, a driving shaft within said instrument, said shaft being composed at least partly of a light-transparent material and being provided with a plurality of translucent surfaces, said shaft being provided with a light receiving portion, a light source positioned adjacent said light receiving portion whereby light is radiated into the transparent interior of said shaft and is transmitted thereby, an instrument dial having indicia thereon mounted concentrically on said shaft adjacent a translucent surface, driving means interconnecting said shaft and said instrument dial, and means including at least some of said translucent surfaces for radiating light from the interior of said shaft to said instrument dial.
2. An instrument dial illumination system comprising, a plurality of rotatable hollow parallel drum dials carrying indicia, said indicia having a light transmissibility different from that of the remainders of said dials, a rotatable shaft co-axal with said dials, said shaft being at least partly composed of an acrylic resin, said shaft having a transparent light-receiving portion and a plurality of translucent light-emitting portions, a light-emitting portion being concentric with the indicia-carrying portion of each said dial, and a lamp adjacent said light-receiving portion whereby the light thereof is received by said shaft, transmitted therethrough and emitted from said light-emitting portions to render said indicia visible by back lighting.
3. An instrument dial illumination system comprising a plurality of counter drum dials carrying indicia, a driving shaft coaxial therewith drivingly coupled to said dials, said dials being hollow and differing from the indicia carried thereby in light transmissibility, said shaft being at least partly composed of an acrylic resin, said shaft having its peripheral surface coated with a metallic layer interrupted at longitudinally spaced intervals to provide circumferential translucent zones respective ones of which are concentric with respective ones of said hollow dials, and a light source adjacent at least one end of said shaft whereby light is transmitted within said shaft to said translucent zones and radiated thereby.
4. An instrument dial lighting system as set forth in claim 3 in which said shaft is provided with a roughened surface over the area occupied by said translucent zones.
5. An instrument dial lighting system as set forth in claim 3 in which the translucent zones of said shaft con sist of grooves of sawtooth cross-section formed therein.
6. An instrument dial lighting system as set forth in claim 3 in which said translucent zones progressively increase in width as the displacement of said light source increases.
7. An instrument dial lighting system as set forth in claim 6 in which the surface of said shaft is provided with a matte finish over the area occupied by said translucent zones.
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