US 3852584 A
A toroidal, gas filled arc discharge flash lamp encircles a reflector having a surface of revolution coaxial with the lamp and comprising the locus of normals to the bisectors of lines tangent to consistent loci on the toroidal lamp and of lines intersecting the axis at a constant angle. Light is reflected substantially uniformly nearly 360 DEG around the reflector and concentrated around an angle somewhat above the horizontal.
Description (OCR text may contain errors)
United States Patent 1191 Levin Dec. 3, 1974 54 ()MNIDIRECTIONAL LI T BEACON 1,799,341 4/1931 Wiegand 240/12 1,939,345 12/1933 061111 et al 240/12 ux WITH TOROIDAL FLASH LAMP 3,474,406 10/1909 0115m 240/12 x  Inventor: Robert E. Levin, South Hamilton,
 Assignee: GTE Sylvania Incorporated,
 Filed: Dec. 22, 1972 [211 App]. No.: 317,791
 US. Cl. 240/4135 R, 240/12, 240/103 R  Int. Cl. F21v 7/00  Field of Search 240/12, 41.35 R, 41.35 F,
 References Cited UNITED STATES PATENTS 1,120,219 12/1914 Mudge 240/103R Primary ExaminerFred L. Braun Attorney, Agent, or Firm-James H. Grover  ABSTRACT A toroidal, gas filled arc discharge flash lamp encircles a reflector having a surface of revolution coaxial with the lamp and comprising the locus of normals to the bisectors of lines tangent to consistent loci on the toroidal lamp and of lines intersecting the axis at a constant angle. Light is reflected substantially uniformly nearly 360 around the reflector and concentrated around an angle somewhat above the horizontal.
1 Claim, 4 Drawing Figures PATENTEL DEB 3 I974 ANGLE ABOVE HORIZONTAL FIG.3
BACKGROUND OF THE INVENTION As disclosed in copending US. Pat. application Ser. No. 212,190, filed Dec. 21, 1971, now Pat. No. 3,771,120 by Robert P. Bonazoli and Donald I. Coggins and erntitled Airport Runway Approach and Reference Lighting System and airport beacon unit may have both a directional gas discharge flash lamp and an omnidirectional flash lamp. The directional lamp or a series of them are aimed in a relatively narrow beam toward and on the correct line of aircraft approaching a runway. The intensity of the lamp is governed by the duration of its discharge. The omnidirectional lamp radiating in all directions serves for earlier location of the runway,- and also serves as a quench tube for terminating discharge of the directional lamp, thereby controlling the intensity of the directional lamp light emission.
The object of the present invention is to provide an improved optical system for multidirectionally radiating light from the quench tube so as to produce a light intensity of nearly uniform magnitude in substantially all directions about. a vertical axis, with maximum intensity at a preselected angle relative to the horizontal plane.
SUMMARY OF THE INVENTION According to the invention a multidirectional light comprisees a lamp of toroidal volume curved in a plane substantially around an axis normal to the plane, a reflector, and means to mount the lamp in fixed relation thereto, the reflector comprising a surface of revolution curved around the lamp axis and defined by a generatrix of the surface intersecting the lamp plane between the lamp and its axis and comprising the locus of normals to bisectors of the angle between two sets of lines, the first lines being tangent to consistent loci on the toroidal volume and-the second lines intersecting the axis at a constant'angle such that the maximum in tensity of reflected light is substantially uniform holder 12 electrically interconnects the lamp terminals with a power supply within the control cabinet 1.
. FIG. 2
The reflector 4 is a polished, surface of revolution about the axis A of a generatrixcurve G defined as follows. A portion of the lamp. 9 is shown in vertical section centered on the horizontal plane P and displaced outwardly a distance D from the axis of revolution and of the toroidal lamp volume. A first line T is drawn tangent to the inward surface of the toroidal volume of the lamp 9. A second line X intersecting the first line T at point 20 is drawn at the angle to the horizontal plane P at which the lowest light ray 21 is desired to radiate from the reflector. In an airport beacon system it is usually desirable for the lowermost ray 21 to issue horizontally, parallel with the ground, hence the line X is parallel, or at a zero degree angle to the plane P. Where, as shown in FIG. 3, it is desired that the lowermost ray 21* issue below the horizontal, the line X* is drawn at a corresponding angle x* to the horizontal. After drawing a bisector B of the angle between the first and secthrough', and concentrated around a selected-angle rel- FIG. 1-
As shown in FIG. 1 an omnidirectional flash lamp system suitable for use in the previously described airport system or for other beacon use is mounted on a control cabinet 1. The beacon comprises a base 2 attaching a clear or tinted transparent cylindrical glass enclosure 3 to the base 2. Mounted on the base 2 is a hollow metallic reflector 4 having top and bottom portions 6 and 7 separably joined at a central seam 8. A flash lamp 9 of toroidal volume encircles the reflector in the plane of the central seam and with the lamp axis coincident with the reflector axis A. Brackets l l on the lower reflector portion 7 support. the lamp, and a lamp 0nd lines T and X, a line N normal (i.e., perpendicular) to the bisector B at the point P represents a reflecting increment on the generatrix G. Repetition of the development of the above described increment willtrac e the complete generatrix G. Successive first lines must be drawn consistently tangent to successively adjacent surfaces of the lamp volume. To construct a particular generatrix curve a point on the line P representing the horizontal plane is selected with regard to the cross sectional radius R of the lamp volume-and to the radius of its torus which equals the displacement D of the torus from the vertical axis. Fora lamp of sectional radius R=0.6O cm. and toroidal diameter D=5.08 cm. a suitable value for the length of the first X1 from the axis A to the generatrix G is 3.11 cm. Other suitable dimensions shown in FIG. 2 are S=9.54 cm., U=ll.30.cm.,
W=.7.76 cm. These three latter dimensions are selected with respect to the desiredlimits of the reflector size and the intensity of concentration; of the emitted light close to the horizontal or ground plane. For greater concentration the extreme upper and lower edges of the reflector are at a greater distance D+S from the axis A than the lamp displacement D, so that one or both of the extreme edges overhang the lamp.
Having located one point on the generatrix curve a line T1 is drawn from the lamp volume, a bisecting line B drawn and a normal N to B drawn at the selected point as described above with respect to point 20. The generatrix curve is then completed graphically by connecting successive normal increments to the first normal increment in a known construction manner.
The above graphic description of the generatrix is summarized as follows: i
The generatrix G is the locus of normals N to bisectors B of the angle between first lines T tangent to the toroidal lamp volume and second lines X intersecting the axis A of revolution at a constant angle x.
An equivalent description of a generatrix reflector may also be made mathematically in spherical coordinates p, g and r shown in FIG. 2 according to the equation below wherein p is the angle in the vertical plane, 3 the angle in the horizontal planes,-r the variable'radius, R the fixed radius of the toroidal lamp volume, D the displacement of the lamp volume center C fromthe vertex V of the reflector, and H a parameter dependent on reflector size:
As shown in FIG. 2 by way of example, the dimensions of the reflector in relation to the toroidal lamp may be 'as follows:
D 5.08 cm.
R 0.60 cm. S 9.54 cm.
U 11.30 cm.
W 7.76 cm.
. Either of the above graphic or mathematical methods will generate a family of reflector curves, all of which satisfy the requirement that the lowermost ray issue from the reflector at the desired minimum angle with respect to the horizontal plane P. Moreover the reflectors so generated will concentrate the beam of rays within a relatively narrow vertical angle above the lowermost ray. Although rays on lines 21 consistently tangent to the inward surface of the lamp volume reflect at the desired minimum angle x, rays such as 22 or 23 in FIG. 2 emanating from outer surfaces of the toroidal volume will be reflected at an angle 1 above, the horizontal. The'angle, however is limited and substantially all concentrated near the horizontal as shown in FIG. 4.
A beacon constructed with the above dimensions will distribute light with the specific distribution shown by the solid line curve I. At the below zero degrees above the horizontal the intensity of radiation is low and dropping sharply. Maximum intensity is at about above horizontal, and above 5 drops off sharply, indicating the efficiency of the present reflector in concentrating light near the horizontal or other desired angle. Similarly the broken line curve I* shows a similar concen- It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.
I claim: 1. A multidirectional light comprising: a lamp of toroidal volume having an axis concentric with the toroidal volume and having its central plane intersected perpendicularly by the lamp axis, the lamp being curved substantially around and equidistant from the lamp axis, a reflector encircled by' the lamp with reflecting surfaces'extending substantially above and below the central plane of the lamp, and means to mount the lamp in fixed relation thereto, the reflector comprising a continuous surface of rev olution curved around the lamp axis and defined by a generatrix of the surface intersecting the central plane of the lamp between the lamp and its axis, wherein the generatrix is defined by the equation:
wherein p is the angle to a given locus on the generatrix in the vertical plane, r the variable radius to the locus, R the fixed radius of the torodial lamp volume, D the displacement of the lamp volume center in the central plane of the lamp from the vertex of the reflector, and H a parameter dependent on reflector size, the central plane of the lamp being vertically asymmetric with respect to the vertex of the reflector so as to produce an asymmetric reflected light distribution pattern with a peak intensity close to and above the lowermost ray issuing from the reflector.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 852 584 Dated December 3 1974 Inventor(s) Robert vin It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
In column 4, claim 1, at the end of line 23, that portion of the equation reading 2 cos2] should read cos In column 4, claim 1, line 24, that portion of the equation reading p2Dp should read 2Dp Signed and sealed this 18th day of March 1.975.
C. IIARSHALL DANE RUTH C. EKSON Commissioner of Patents Attesting fficer and Trademarks ORM PO-1050 (10-69) USCOMM-DC 6O376-P69 U.S. GOVERNMENT PRINTING OFFICE ISQ 0366-334