US 3354428 A
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Description (OCR text may contain errors)
Nov. 21, 1967 T. H. PROJECTOR ETAL 3,354, 8
OSCILLATING COLOR FILTER SINGLE STATION RANGE LIGHT Filed April 20, 1965 2 Sheets-Sheet 1 G/QEEN N4 y prgp POSITION 3* Z INVENTOR THEODORE A. Pea/scrap POBEPT P/A/K/lVE/V ATTORNEY 1967 T. H. PROJECTOR ETAL 3,354,428
OSCILLATING COLOR FILTER SINGLE STATION RANGE LIGHT Filed April 20, 1965 2 Sheets-$heet 2 O (T y p A V //X(/ A" 55/ I 6 United States Patent Office 3,354,423 Patented Nov. 21, 1967 3,354,428 OSCILLATING COLOR FILTER SINGLE STATI'GN RANGE LIGHT Theodore H. Irojector, 3304 Edgwood Road, Kensington, Md. 20795, and Robert S. Rinlrineu, 47fl8 Topping Road, Rockville, Md. 20853 Filed Apr. 20, I965, Ser. No. 449,580 4 Claims. (Cl. 340-29) ABSTRACT OF THE DISQLOSURE This invention relates to range lights, particularly for river and harbor navigational purposes wherein a navigator is to be guided through a deep water channel of the river, harbor, or the like, and is a modification of our previously filed co-pending application S.N.26l,688 filed February 28, 1963, now Patent No. 3,311,877.
The feature of the invention resides in producing a pair of adjacent beams of two different colors which oscillate back and forth over a navigational course line which is in the plane of the optical axis of a lens projection system. The color beam oscillation is effected by reciprocation of a pair of color areas comprising a dual color filter.
Much development work has been done in the matter of providing beacons for the guidance of navigators in channels and along coasts. Beacons intended to guide mariners along channels (range lights, as they are called) usually take the form of two spaced lights. The two lights are located on an extension of the center line of the section of the channel for which they provide guidance, the farther away being above the nearer light. When a mariner is on the channel center line, the farther light appears directly above the near light. When he is off the channel center line, the two lights are laterally separated, the amount of the separation being an indication of the mariners distance from the center line.
However, a number of range lights have been developed of the so-called single-station type wherein only one light or assembly of lights at a particular point is used. In the matter of single station range lights, various systems involving multicolor units, flashers and coacting time flashes have heretofore been known.
The basic principle involved in a single station system is the provision of means such as lights of different color on each side of a White beam to indicate to a pilot whether he is on course, or to the left or right of the course depending on which colored light he sees, or depending on some other manifestation effected by the coacting beams, either with or without a movement of such beams.
Arrangements previous to our prior application had various drawbacks, such as complexity of mechanism or confusing manifestations, or expensive construction, or the like. Accordingly, it is the primary object of the present invention to provide a simple and dependable single-station range light which can be manufactured economically and which will give a signal more positively recognizable for off or on course conditions than those of the prior art. The present application has for an object a further simplification of construction.
Other objects and features of the invention will be apparent from the description to follow.
Briefly, the invention contemplates an optical device similar to a lantern-slide projector and the provision of a composite red and green color filter mounted for reciprocation and beam projection so that the motion of the projected beams crossing and re-crossing a desired course line in a channel takes place in a particular sequence of angular positions, with a dwell of a predetermined time at each position and rapid traverse between positions. By virtue of mechanical reciprocation of the filter in a horizontal plane, the center line of the composite beam swings to and fro through a narrow predetermined angle. However, the motion is such that the composite beam center line is preferably stationary at certain positions on each side of the course line.
A navigator in the channel can ascertain by the duration of time in which he sees one color of beam as compared with the length of time that he sees the other color whether he is on course or off course and to what extent. In other words, the navigator sees the light changing from, say, red to green, repetitively, and, depending on the position in which he is relative to the proper course that he is to follow, he will note that one or the other of the colors is seen for a longer period. In that way, he determines whether he is to the left or right of the course. When he sees only one color of light steadily he is apprised of the fact that he is further ofi course than when he sees two colors of different time duration. The color that predominates in time duration apprises him as to whether he is left or right of the course. When he is on course he sees the portions of the composite beam alternate in color, and the colors are of equal time duration.
Ideally the two light beams are precisely divergent so that the inner adjacent edges of their beams are coincident and sharp. Thus, as the composite beam sweeps the channel from side to side, the transition from one color to the other as observed by a mariner would be abrupt and complete. In practise, such precise cutoffs are unattainable, and some overlapping or irregularity of the two beams at their contiguous edges is unavoidable if a continuous light signal without occulting is desired. The equipment therefore is designed to have adjacent beam edges as sharply defined as is practicable, but there will nevertheless be narrow transition regions in the channel, between the regions of desired signal presentation, where some part of the signal sequence will not be red or green, but some color representing an additive combination of red and green, such as yellow, or the transition zone may appear dark or reduced in intensity. This does not alter the basic presentations as outlined above, but means that the simple basic presentations are complicated to a small extent by the addition of narrow transition zones between the major, desired signal presentation zones.
The mechanical arrangement may be very simple and can consist of a slidable frame which holds the composite filter, much the same as the slide holder in a lantern slide projector. Any suitable linkage arrangement, which may include a cam, can be arranged to reciprocate the slidable frame and, hence, the integral redgreen light beams sweep to and fro over the course line. The layout of the cam in the present disclosure provides four angularly related dwell positions having a rest time of about one second, as in one version shown in the prior application.
The filter assembly moves very rapidly, in perhaps a tenth of a second, between positions. The sequence of movement to the various dwell positions, assuming four geometrically consecutive angular positions is in the order 1-3-2-4 and on each movement between dwell positions the juncture of the composite beam crosses the channel course line. Such motion is continuous and the effect is to provide a difference in the length of time each color is seen by a navigator depending on his position with reference to the course line.
The time interval of one second dwell at each of the four positions described above is, of course, arbitrary. Different conditions may indicate variation therefrom U and, of course, it is only the design and/ or speed of the cam which needs to be changed to produce longer or shorter dwell periods.
In the drawing:
FIGURE 1 is a schematic plan view showing the basic components of the invention consisting of a projection system and a movable composite two-color filter;
FIGURE 2 is a time study chart of the relative durations of specific light color seen by a navigator in various positions in a channel;
FIGURE 3 is a plan diagram of a river or harbor channel showing the presentation of the composite beam extending into the channel for [our dwell positions;
FIGURE 4 is a plan view partially in section showing an exemplary construction of the invention;
FIGURE 5 is a section taken through 5-5 of FIG- URE 4; and,
FIGURE 6 is a front elevation of the general construction partially in section to a somewhat smaller scale than shown in FIGURES 4 and 5.
Referring to FIGURE 1, the present invention comprises a projection system having projection lens system It which projects an image of composite color filter (15a red and 1512 green) through aperture 12, illumination being provided by condenser lens system 18, lamp 2i, and reflector 23 all in a well known manner. The filter elements 15a and 15b abut at the common edge E, which is the center line of the composite filter, FIGURE 5, and the center position of edge E with respect to the course line K is in a vertical plane therewith, which plane contains he optical axis of the lens system. Filter 15 is carried in a suitable slidable frame 26 which is reciprocated in the same manner as the oscillatory movement of the prior application. Thus, a link Bill is pivotally connected at 32 which link is actuated by an oscillatory arm 33 to effect frame reciprocation. The composite color filter effects projection of red and green beams with boundary M, as shown, and the effect of the motion produces a changing color signal as shown in FIG. 2, which corresponds to FIG. 4 of the prior application. Accordingly, a navigator would see a series of signals of the same or differing color, and for time periods depending on his position in a channel, as illustrated in FIGURE 3, and all as set forth in the prior application and hereinbelow.
The composite filter may be of any suitable color materials such as pieces of glass or plastic, etc, mounted edge to edge in rectangular frame 26 in any appropriate manner, element 15a being red and element 15b being green.
Referring to FIG. 4, the actuation is as described in our prior application (like reference characters being used.) Thus arm 33 is pivotal on a fixed pin 37 which may be placed in any arm aperture 40 to vary the amplitude of oscillation of the arm. Spring 43 biases the cam roller 46 on arm 33 against cam 50 having lobes A, B, C, D.
The above components may be mounted on a support plate 55, pin 37 being fixed to the plate and the shaft for cam Stl extending from gear box and motor combination designated generally as Q in FIGURE 6.
Any suitable projector housing may be designed for operation of the invention. Thus, in FIGURES 4, 5 and 6, the rectangular housing 60 holds the optical components and may be provided with side housing 68 and 72 registering with side slots to shield the filter frame 26 as it reciprocates transversely of the housing. Suitable vertical and horizontal rollers, 89 and 84, respectively, may be provided for guidance and support. The motor and mechanism may be shielded by housing 99, and plate 55 may have suitable support structure (not shown) depending on type of installation.
The center line M of the projected composite beam sweeps across the desired course line K of the channel (FIGURE 3) and the beam angles are necessarily narrow ifor accuracy. The beam angle sweep may be of the order of from one to ten degrees for practical operation under most conditions, as exemplified by the are IV between lines A and D (FIGURE 3), drawn to a somewhat larger angle for clarity. The origin point 0 represents the projector position in FIGURE 3.
The lobes or dwells A, B, C, D of the cam 50 effect reciprocation of the filter frame 26 so that there are a plurality of corresponding stationary or dwell positions of beam juncture on lines A, B, C, D (FIGURE 3), as shown in consecutive geometric sequence, in dashed lines, although the sequence of movement is not in geometric sequence, as will be explained.
The dwell at each such position is for an arbitrary period of about one second and the cam layout is such that the motion of the beam center line M follows the order, from position to position, ACBDA etc. (FIGURE 3), as indicated by the arcuate arrows I-II-III-IV- etc.
The time consumed in the to and fro passing from position to position is very short, relative to the dwell time, being of the order of a tenth of a second. Accordingly, the change of color, when there is one, appears abrupt.
It will, of course, be understood that the channel depicted in short-dash lines on FIGURE 3 is a predetermined deep water passage-way through which boats must navigate in order to avoid shallows, sandbars, etc., which may exist on each side of the channel. Thus, while a navigator is in the channel, he is safe, and the signals visible to him apprise him as to his relative position with respect to the width of the channel. Accordingly, he is guided in a manner to be described below along the course line K in mid-channel position and he is aided in finding and in following the course line by means of the relative time periods in which he sees alternating red green signals, i.e., color portions of the composite beam, as they sweep back and forth across the course line.
The course line K, as shown in FIGURE 3, is fixed in the plane of the optical axis of the projector, while the dwell position lines ABCD are the location of the beam center line M in the order ACBD as the beam sweeps the channel.
The design of the system is such that the beams will angularly diverge to a degree sufficient to give full radiation of their respective colors from center line K to beyond the channel sides. For example, as seen in FIGURE 3, the red beam would have an angular coverage from the origin 0 of the angle between lines K and L while the green beam would give the angular coverage between lines K and. N. The composite filter is disposed at or close to the focal plane of lens 10 so that the composite beam as seen from an operating distance, are of proper angular coverage, and the arcuate arrows of FIGURE 3 will be understood to depict the direction and extent of motion of beam center line M in moving to and from the several dwell positions A-BCD. The extent of movement of the filter would be small, of the order of a fraction of an inch for most channels, as illustrated by the double arrow R in FIGURE 5, which is actually enlarged for clarity.
Bearing in mind that owing to the layout of the cam 50, the beam center line M moves between dwell positions in the order ACB-D and remains in said positions for one second, a navigator at point Y in the channel (FIGURE 3) would see a continuous red light, as illustrated in the chart of FIGURE 2, for the navigator position on the ordinate, designated A-L. This is due to the fact that for every dwell position of the lights only the red beam is visible above the line A, since the greatest clockwise rotation of the center line M is only up to position line A and all light clockwise of the line A is always red. Accordingly, the navigator at point Y knows he is oh an accurate center course and will, therefore, seek the center course in the manner described below.
as would a navigator at the point X (actually outside the channel) who would see only a continuous green beam, since the maximum counter-clockwise sweep of the center line would always maintain the green beam visible toward X, as indicated by the bar in FIGURE 2, designated D-N. If, however, the navigator is in the zone between A and B, say at the point Z, he will see a series of alternating color signals wherein the red signal lasts three seconds and the green signal lasts one second, respectively, as indicated in the bar designated A-B of FIGURE 2. This is due to the particular sequence of oscillation of the lights relative the course line K. Thus, the navigator at Z (below line A) sees the green signal for one second when the beam center line M coincides with line A; when the line M goes to C (arrow I) for another dwell, the navigator sees the red signal, for one second, then line M goes to line B (arrow II) and the navigator sees the red signal for a second second, and finally the line M goes to D (arrow III) and the red signal is seen for a third second. Subsequently, the beam center line M sweeps back to A (arrow IV) and the sequence is thus continually repeated.
In a similar manner, a navigator in zone C-D would see three seconds of green alternating with one second of red, as indicated on FIGURE 2 by the bar C-D.
Accordingly, a navigator, interpreting the time ratio of signals, red versus green, would know where he is in the channel and steer in the correct direction toward course line K. When he is on line K, he would see equal time interval signals, one second red, one second green alternating, as illustrated on FIGURE 2 for the bar B-C, On Course. This follows from the symmetry of the dwell positions with respect to the course line; and observing the movements IIIIIIIV of the juncture line it will be noted that the red and green beams alternate on channel course line K (or anywhere in the zone B-C) since each motion of the beam center line M crosses the course line K.
The crux of the invention is the identification of a course line by adjacency of two signal beams of differing color moving in unison to effect a difference in the relative lengths of time a navigator sees each color, depending on his position in a channel. Thus, the arrangement of a two dwell position system shown in FIGURES 5 and 6 of the prior application could be used with the present invention, and, in fact, the system could be used without dwells, although the use of dwells is preferred. The primary condition to be met is that the center line of the beams sweeps the course line for substantially equal time periods with some portion of each beam always on its respective side of the course line. Further, although the ideal beam condition is that there be an infinitely thin separation between the beams, as seen by a navigator, such ideal is impossible of attainment and some light blending or occulation may occur. As a practical matter, if a navigator is close to or directly on a dwell position line A, B, C, -D looking towards the lights, he may see an ambiguous blend of the beam colors. However this can be interpreted without difiitculty. Thus, for example, if the sequence of signal colors is red-ambiguousred-green-etc., the mariner must be on line B in the channel.
Having thus described our invention, we are aware that various changes may be made without departing from the spirit thereof and, therefore, do not seek to be limited to the precise illustrations herein given, except as set forth in the appended claims.
1. A range light comprising a lens projection device and a composite color filter, said filter being a generally planar member having a pair of transparent color filter elements disposed with a common edge, a support means for said member to guide and support said member for reciprocal movement wherein said common edge sweeps back and forth across the optical axis of said lens projection device, actuating means operatively connected to said filter to effect repetitive reciprocal movement thereof, and a mounting structure for said projection device whereby the optical aXis thereof may be disposed on a predetermined course line to be followed by a naviga- 'tOI.
2. A range light as set forth in claim 1, said support means comprising a frame for said filter elements, said projection device comprising a housing and roller means within said housing supporting said frame for reciprocal movement thereof with respect to said optical axis.
3. A navigational single station range light comprising a projection device and movable du-al filter having two adjacent color areas, means for repetitively oscillating said filter between at least two positions so that the projected color beams thereof oscillate back and forth across a navigational course line to be followed, said means comprising a device for effecting equal dwell times for said beams at said positions.
4. A range light as set forth in claim 3, wherein said color areas meet in a substantially straight line oscillating back and forth across the optical axis of said projection device.