|Publication number||US3732417 A|
|Publication date||May 8, 1973|
|Filing date||Jun 16, 1971|
|Priority date||Jun 16, 1971|
|Also published as||CA958393A, CA958393A1, DE2229120A1|
|Publication number||US 3732417 A, US 3732417A, US-A-3732417, US3732417 A, US3732417A|
|Inventors||Nordquist M, Nordquist R|
|Original Assignee||Grimes Manuf Co|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (4), Referenced by (20), Classifications (6)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent 1 1 Nordquist, deceased [451 May 8, 1973  Inventor:
 Assignee: Grimes Manufacturing Company,
Urbana, Ohio  Filed: June 16, 1971  Appl. No.2 153,642
521 U.S.Cl. ..240/41.3,240/7.4, 240/1061 51 rm.c| ..F2lv 13/04  FieldotSearch ..240/41.3,7.4,41.15,
 References Cited UNITED STATES PATENTS 1,350,295 8/1920 Champeau ..240/106. 1 X 2,366,356 1/1945 Rolph ..240/93 Hamel et al. ..240/93 Foulke ..240/106 R Primary Examiner-Richard L. Moses Attorney-Marechal, Biebel, French & Bugg  ABSTRACT A reflector and lens projecting assembly is adaptcd to project a rectangular or square pattern of light from a conventional circular reflector. A prismatic lens having four 90 segments is positioned in front of the reflector and directs the light from the reflector into four mutually over-lapping segments in which radii of the unmodified pattern from the reflector form the boundaries of the square or rectangular pattern as modified by the lens. Embodiments are shown using light modifying prisms in which the thick portions of the prism are at the periphery of the lens and in which the thick portions of the prism are at the center of the lens.
9 Claims, 10 Drawing Figures PATENTEDNAY am: 3.132.41 7
sum 2 0F 3 FIG-4 LLl [T5 PATENTED A 3.732.417
SHEET 3 BF 3 FIG-6 I '2 FIG-7 2 I 3 so 4 I Q If i B 5A B I A so FOCAL POINT \OF ELLIPSE V AXIS 52 I l SQUARE LITE PROJECTOR USING PRISMATIC LENS BACKGROUND OF THE INVENTION and reflector structures in which a rectangular or square pattern of light is formed by canting, filting, or modifying portions of a conventional reflector so that the resulting reflector has a non-circular cross section. Projected images or fields from the reflector segments are caused to be defined and overlap each other to form a desired geometric pattern of light of substantially uniform intensity thereacross. The lamp structure shown in that application has met with commercial success and, for example, is presently being used for the reading light lamp in the Boeing 747 aircraft/ However, it does require that the reflector portion of the lamp be especially modified, but has the advantage that no special lens is required, thereby creating a light-weight and effective projector construction.
SUMMARY OF THE INVENTION The present invention is directed to another arrangement by which a rectangular or square pattern or field of light defined by mutually overlapping light segments, can be formed from a conventional non-collimating circularly continuous parabolic or elliptical reflector. For example, the reflector may be of the conventional parabolic form in which the filament of the bulb has been displaced either ahead of or behind the focus to form a diverging, spreading filament image and light pattern. on the other hand, the reflector may be formed as a revolved ellipse that is, one in which a circularly continuous reflector has been generated by revolving a segment of a tilted ellipse about an axis. Examples of the generation of such reflectors are disclosed in the above-identified copending application, and another example of such reflector is disclosed, for example, in Nordquist U.S. Pat. No. 2,602,135 of July I, 1952. Revolved ellipse reflectors are in common use where it is desired to provide a spreading pattern or field of light.
With either type of reflector described above, I employ a prismatic lens which comprises individual arcuately arranged prism segments. Each prism segment is arranged to intersect a corresponding segment, such as a quadrant, of light from the reflector and to displace this segment laterally with respect to a center axis. The lateral displacement caused by the prism segment is similar, in effect, to that caused by the modified reflectors of copending application Ser. No. 724,688 now US. Pat. No. 3,588,493.
Each prism segment forms a corresponding segment of the light pattern which is correspondingly displaced so that a mutually overlapping light pattern or field is formed of substantially uniform intensity from side to side or diagonally from corner to corner. When four equal 90 segments are employed, a rectangular pattern is formed in which the sides of the pattern were formerly radii of the unmodified circular pattern from the reflector. Such square pattern is smaller than the unmodified pattern by a factor of pi.
The individual prism segments of the lens may be formed with the thicker portion at the periphery of the lens or with the thicker portion at the center of the lens, depending upon the reflector and position of the light source. When the the axis of tilt of the elliptical reflector is small, the light rays from any side of the reflector will cross through each other and will become displaced on opposite sides of the center line at a given field plane. In this case, the thicker portions of the prisms will be at the periphery of the lens to provide the required image displacement. On the other hand, if the elliptical reflector is formed with a revolved ellipse in which the focal point of the ellipse for any cross section thereof, lies on a more substantially tilted axis, individual rays from any segment thereof will converge at a narrower angle and the individual segments from such a reflector, at a given focal length, may be brought together into the desired mutually overlapping relation by a prismatic lens in which the segments of the prism have their thicker portions at the center of the lens.
If a parabolic reflector is used in which the filament is displaced ahead of the focus, a prismatic lens is used in which the thicker portions are at the periphery. On the other hand, if the filament is positioned behind the focus to form a diverging and non-inverted-pattern of light, then a prismatic lens is used in which the thicker portions are at the center of the lens. Any embodiment disclosed herein, it is within the scope of the invention to reduce the overall thickness of the lens by the Fresnel technique.
It is accordingly an important object of the invention to provide a simplified projection and lens arrangement by which a uniform rectangular or square pattern of light is formed from a circularly continuous reflector.
Another object of the invention is the provision of a projector having a prismatic lens formed in four essentially equal quadrants or segments, each segment defining an individual prism which is essentially identical to that of the adjacent prism, and which are effective with a reflector to form a pattern of light having a corresponding number of straight sides.
A further object of the invention is the provision of a projector and lens assembly-which may be used to form a rectangular or square pattern of light which pattern is smaller than the pattern developed by the reflector alone and which is of generally uniform intensity across the pattern.
Another object of the invention is the provision of a projector and lens as outlined above, which produces a square pattern of light from parabolic or elliptical reflectors.
These and other objects and advantages of the invention will be apparent from the following'description, the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a diagram of a reflector and the light pattern formed by the reflector to which the present invention is applied;
FIG. 2 is a view looking into the reflector;
FIG. 3 is a view of the system of FIG. 1 showing the manner in which a lens quadrant modifies a portion of the light from the reflector;
FIG. 4 is a further diagram of the reflector and lens combination of this invention showing a rectangular pattern formed thereby;
FIG. a is a plan view of the lens used in the embodiment of FIGS. l4;
FIG. 5b is a side view of the lens;
FIG. 6 is a further diagram showing another form of reflector to which the invention may be applied and the pattern produced by such reflector;
FIG. 7 is a diagram showing a pattern as formed by a modified lens of this invention;
FIG. 8a is a plan view of the modified lens; and
FIG. 8b is a side view thereof.
DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG. I, an elliptical reflector is illustrated generally at 10, and a light source, which may be a filament bulb, is illustrated at 12 positioned within the reflector 10. The reflector 10, as shown, is of the tilted ellipse type in which the surface 14 of the reflector is formed as a tilted and revolved segment of ah ellipse. The foci at the filament l5 and at the point 16 lie on an inclined axis 17. The reflector is generated by revolving about the center line so that the locus of all points forming the secondary focus 16 form a circle with its center on the center line. Depending upon the inclination of the axis 17, the light field 18 may be either broad or narrow. The concentric circles or rings illustrated at 20 are provided merely for the purpose of reference points and, in fact, may actually comprise brighter rings of light due to the rotation of the filament image, when a coil-type axial filament is employed as the source 12. However, for the purpose of this invention, the concentric rings may be considered as representing the reflected images from the reference points 1, 2, 3, 4 and 5 as shown on the reflector and as designated on the field 18.
In FIG. 1, the images have crossed over each other so that light from the quadrant A of the reflector has passed through inversion at the focus 16 and occupies a diametrically opposite position illustrated by the same reference points 5, 4, 3, 2', and 1 on the light field. Similarly, the light from the quadrants B, C and D occupy reversed positions shown by the corresponding letters on the light field. While the light field 18 is shown-as having been developed by a revolved elliptical reflector, essentially the same light pattern for the purpose of this invention may be developed by a conventional parabolic reflector in which the filament point has been displaced forwardly of the focus, so that the reflector becomes, in effect, an image-inverting reflector with respect to the filament image.
. Referring to FIG. 3, a prism is shown as being interposed'between the focal point 16 and the open side of the reflector 10. In this instance, the thicker portion of the prism is at the peripheral edge. Since the prism bends the light toward its thicker side, if the prism 25 is made as a 90 segment of a circle, corresponding to the segment A of FIG. 2, it may be chosen with a taper sufficient to shift the quadrant A of the light field with respect to the center line a distance approximately equal to the radius R of thepattern l8 multiplied by the square root of 2. The sides 26 and 27 of the moved segment, which equals the radius R, would form two of the sides of the completed square. Thus, if a lens is made up of four 90 prism segments 25, one for each quadrant A, B, C and D of the lens 10, the corresponding 90 segments of light would be formed into a mutually overlapping pattern illustrated generally at 30 in FIG. 4.
Such a composite prismatic lens for this purpose is illustrated at 32 in FIGS. 4 and 5 in which the individual arcuate segment 25A, B, C and D are joined along common radii, each comprising a segment of a complete circular lens. The composite pattern 30 is made up of the four displaced pattern segments A, B, C and D; and the perimeter lines comprise former radius lines of the pattern 18. If desired, a Fresnel technique may be applied to the lens 32 to reduce its thickness. The lens 32 will perform essentially the same with the tilted elliptical reflector shown in FIG. 1 in which there is image reversal, and with a parabolic reflector in which the filament has been moved forward of the focus so that image reversal occurs.
The embodiment of the invention shown in FIGS. 6-8 is one in which the thicker portion of the prism lens is located at the center of the lens. This may be a more desirable arrangement in order to reduce the overall weight of the lens as the mass of the lens would be less as compared to an embodiment in which the thicker part of the prism is at the circumference. Looking first at FIG. 6, a revolved elliptical reflector 50 is tilted along an axis 52 which is at a rather substantial angle to the center line. In this instance, a circular field 58 is formed prior to crossover of the images from the individual reflector segments A, B, C and D. Again, reference points 1 through 5 are shown on the surface of the reflector 50 and the corresponding points are shown on the field 58. Thus, a reference point 5 in the embodiment of FIG. 6 occupies the center of the field 58 whereas in the embodiment of FIG. 1 it occupied a position on the periphery of field 18. The reflector 50 may also be a parabolic reflector but one which the light source or filament has been displaced inwardly of the focus, rather than outwardly, to form a spreading with respect to each quadrant of the lens. This results in a bending of the light inwardlytoward ,the center line and forms the fully overlapping image or'pattern 64 as shown in FIG. 7. The pattern 64 is essentially identical in appearance and shape to that of the pattern 30,-ex
cept that the light making upthe pattern is from reversed positions with respect to the reflector. This pattern 64 is also essentially uniform in intensity throughout, has a sharp fall-off of light outside the pattern, and is smaller than the field 58 by a factor of pi. Again, as in the case of the lens 32, a Fresnel technique may be applied to the lens to reduce its overall thickness.
A parabolic reflector in which the light source is displaced axially inwardly of the focus is not image inverting. Since there is no crossing over of the reflected light with respect to the center line of the reflector, the pattern formed is very much like that of pattern 58 and accordingly essentially the same lens 60 with prism segments having the thicker portion oriented at the center line or axis may be used for quadrature image displacement into a mutually overlapping pattern 64.
Either of the embodiments shown may be used with advantage in sealed beam lamps and the like, in which be desired to form each lens segment as a series of 5 small FResnel prisms, to reduce overall thickness.
While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention.
What is claimed is:
1. A reflector and lens projecting assembly adapted to project an essentially square pattern of light from a lamp and a generally circular reflector, comprising a source of light, a circularly continuous projecting reflector associated with said source to project a diffused generally circular pattern of light therefrom, and a lens interposed to intercept reflected light from said reflector having four essentially 90 segments, each said segment consisting of a prism positioned to intercept a corresponding segment of reflected light, and effecting lateral displacement of a corresponding segment of said pattern to form a composite essentially square light pattern in which each side thereof is approximately equal to a radius of said circular pattern formed without the lens.
2. A reflector and lens projecting assembly adapted to project an essentially square pattern of light in combination with a light source and a reflector, comprising means defining a source of light, a circularly continuous projecting reflector positioned with respect to said light source to project a non-focusinggenerally circular pattern of light therefrom, and a circular lens interposed to intercept reflected light from said reflector, said lens having four arcuate segments each defining an individual prism, each segment being positioned to intercept light from a corresponding segment of the reflector and to effect lateral displacement thereof resulting in a mutually overlapping square pattern of light in which each side of the resulting square is approximately equal to a radius of said circular pattern.
3. The assembly of claim 2 in which said circular pattern when formed on an image plane, in the absence of said lens, is one in which the images from one side of the reflector cross over, and are inverted, with respect to the center axis of the reflector, and in which each said prism segment of the lens is formed with its thicker portion at the lens periphery.
4. The assembly of claim 2 in which said circular pattern, when formed on an image plane in the absence of said lens, is one in which the images from one side of the reflector are formed on the same side of the center axis of the reflector, and in which each said prism seg ment of the lens has its thicker portion substantially at the center of the lens.
5. The assembly of claim 2 in which said reflector is parabolic.
6. The assembly of claim 2 in which said reflector is elliptical.
7. The assembly of claim 2 in which each said lens segment displaces its associated said image a distance of approximately the radius of the said circular pattern multiplied by the square root of 2. j
8. lens element for use with a pro ecting reflector comprising four essentially equal and identical prismatic segments, each said segment being symmetrically positioned with respect to each other with the thicker portion of each segment being positioned at the lens center, and each said segment having one surface thereof lying in a plane common with a corresponding said surface of each of said other segments.
9. A lens element for use with a projecting reflector comprising four essentially equal and identical 90 prismatic segments, each said segment being symmetrically positioned with respect to each other with the thicker portion of each segment being positioned at the lens periphery, and each said segment having one surface thereof lying in a plane common with a corresponding said surface of each of said other segments.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US1350295 *||Apr 18, 1919||Aug 24, 1920||Kirby Champeau Co Inc||Illuminating means|
|US2124417 *||Jun 18, 1937||Jul 19, 1938||New York World S Fair 1939 Inc||Lighting fixture|
|US2366356 *||Oct 14, 1942||Jan 2, 1945||Holophane Co Inc||Luminaire|
|US3344268 *||Sep 12, 1963||Sep 26, 1967||Refractor for usb in uniformly illuminating a polygonal area|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3941993 *||Oct 9, 1974||Mar 2, 1976||C G R Alexandre||Illuminating device in particular for an operating table|
|US4670825 *||Dec 31, 1985||Jun 2, 1987||Fouke Herbert A||Reflector for use in uniformly illuminating a polygonal area|
|US4937715 *||Jan 26, 1989||Jun 26, 1990||Kirschner Medical Corporation||Lamp system for operating theatres and the like|
|US4994945 *||Dec 22, 1989||Feb 19, 1991||Kirschner Medical Corporation||Lamp system for operating theatres and the like|
|US6244732||Apr 16, 1999||Jun 12, 2001||Stanley Electric Co., Ltd.||Lamp|
|US6969181||May 8, 2001||Nov 29, 2005||Genlyte Thomas Group Llc||Fully recessed unit equipment luminaire|
|US7607787 *||Dec 1, 2005||Oct 27, 2009||Casio Computer Co., Ltd.||Light source unit and projector system|
|US7607810 *||Sep 20, 2005||Oct 27, 2009||Valeo Vision||Signalling light, in particular for an automobile|
|US7817909||Dec 19, 2005||Oct 19, 2010||Sharp Kabushiki Kaisha||Optical device and light source|
|US7819533 *||Feb 23, 2006||Oct 26, 2010||Casio Computer Co., Ltd.||Light source unit and projector apparatus|
|US8098434||Sep 22, 2010||Jan 17, 2012||3M Innovative Properties Company||Optical decollimator for daylighting systems|
|US20050047137 *||Aug 28, 2003||Mar 3, 2005||Era Optoelectronics Inc.||Cross-shaped laser rays generator with non-spherical lens|
|US20060062010 *||Sep 20, 2005||Mar 23, 2006||Patrice Collot||Signalling light, in particular for an automobile|
|US20060126341 *||Dec 1, 2005||Jun 15, 2006||Casio Computer Co., Ltd.||Light source unit and projector system|
|US20060197925 *||Feb 23, 2006||Sep 7, 2006||Casio Computer Co., Ltd.||Light source unit and projector apparatus|
|US20080279541 *||Dec 19, 2005||Nov 13, 2008||Sharp Kabushiki Kaisha||Optical Device and Light Source|
|EP0950847A2 *||Apr 15, 1999||Oct 20, 1999||Stanley Electric Co., Ltd.||Lamp|
|WO2004001286A1 *||Jun 19, 2003||Dec 31, 2003||Bergkvist Lars A||Light fittings|
|WO2006068264A2 *||Dec 19, 2005||Jun 29, 2006||Sharp Kk||Optical device and light source|
|WO2009147289A1 *||May 27, 2009||Dec 10, 2009||Valopaa Oy||Apparatus for directing and illuminating light|
|International Classification||F21V5/00, F21V5/02, F21S8/00|