US3798445A - Traffic signal lens - Google Patents

Traffic signal lens Download PDF

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Publication number
US3798445A
US3798445A US00116386A US3798445DA US3798445A US 3798445 A US3798445 A US 3798445A US 00116386 A US00116386 A US 00116386A US 3798445D A US3798445D A US 3798445DA US 3798445 A US3798445 A US 3798445A
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United States
Prior art keywords
lens
lenticular elements
elements
lenticular
horizontal
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Expired - Lifetime
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US00116386A
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English (en)
Inventor
J Miles
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EAGLE SIGNAL CONTROLS CORP A CORP OF DE
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Gulf and Western Industries Inc
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Assigned to WICKES MANUFACTURING COMPANY, A CORP. OF DE. reassignment WICKES MANUFACTURING COMPANY, A CORP. OF DE. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: GULF & WESTERN INDUSTRIES, INC., FORMERLY GULF & WESTERN INDUSTRIES, INC.,
Assigned to EAGLE SIGNAL CONTROLS CORP., A CORP. OF DE. reassignment EAGLE SIGNAL CONTROLS CORP., A CORP. OF DE. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: WICKES MANUFACTURING COMPANY, A DE. CORP.
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V5/00—Refractors for light sources
    • F21V5/04—Refractors for light sources of lens shape

Definitions

  • the invention relates to a traffic light lens preferably [5H Int Cl F 5/04 Gozb 27/00 formed of polycarbonate material.
  • the inner face of [58] Field 540/106 1 350/167. the lens is formed in a mosaic arrangement of rectan- I 340/383 gular, Ienticular areas.
  • the lenticular areas of the lens are of two types, flat areas and curved areas.
  • the 56] References Cited curved lenticular areas, which form the greater part of the inner surface of the lens, are curved in both verti- UNITED STATES PATENTS cal and horizontal directions.
  • the flat areas are. tilted 3,383,676 5/1968 Nagel 240/l06.l x to project the light downwardly f the horizontal a 1 1 246x axis of the traffic light assembly. 2.907.249 10/1959 Hjerm stad 240/4l.4 X 12 Claims, 11 Drawing Figures Pmmmmms am y I 3798.445
  • FIG-3 2 FIG-2 I8 20 W ll/I91 F l G.- 4 INVENTOR.
  • JOHN R. M l L ES [8 20 I8 BY M 5 /77%,/%% ⁇ 50% ATTORNEYS PAIENTEUMRW 1914 3L798L445 SHEET 2 OF 3 FIG-7 MAXIMUM CURVED SEGMENT ANGLE) HORIZONTAL TOTAL DOWN-SPREAD FIG-9 INVENTOR.
  • JOHN R. MIL ES ATTORNEYS TRAFFIC SIGNAL LENS The present invention relates to traffic signals and more particularly to a lens construction for such signals.
  • a traffic light consists generally of a number of housings each of which is provided with a parabolic reflector, an incandescent light bulb located at the focus of the paraboloid and a lens or cover which seals the front of the reflector.
  • these signals are mounted over the street or sidewalk at an intersection and are operated by suitable control means to regulate the flow of traffic through the intersection.
  • the light is projected through a lens of the signal so that, when it is viewed from the area in front of the signal, the light is clearly visible from the desired locations of the observer, whether he is a pedestrian on the street or a driver of a motor vehicle.
  • substantially all of the light projected through the lens should be directed into the desired range of the observer.
  • the prior lens designs have been intended for either glass or acrylic lenses.
  • Glass lenses are difficult to manufacture, of high weight, and are easily cracked, broken, scratched or damaged.
  • the use of acrylic lenses overcomes some of the disadvantages of the glass lenses.
  • acrylic lenses are unable to withstand high temperatures without damage. Serious deformation and loss of color in acrylic lenses has been observed in standard traffic lamps equipped with a watt bulb.
  • a further object of the invention is the provision of a traffic light lens which is molded of polycarbonate to provide a durable lens capable of withstanding the heat generated by the light bulb of the traffic light assembly.
  • a lens which has its inner surface formed in a mosaic of substantially rectangular shaped lenticular areas.
  • the majority of these lenticular areas are curved both horizontally and vertically to direct the projected light throughout the desired observation range.
  • the remaining lenticular areas are flat surfaced to direct a portion of the light straight ahead from the signal. All of the lenticular areas are inclined slightly so that the straight ahead light and the light pro- 10 jected through the curved lenticular areas is directed at a small angle downwardly from the horizontal.
  • FIG. 1 is a fragmentary rear elevation view of a traffic light lens constructed in accordance with the principals of the present invention
  • FIG. 2 is a vertical sectional view taken along the line 2-2 of FIG. 1;
  • FIGS. 3 through 5 are fragmentary horizontal sectional views taken along the lines 3+3 to 5-5, respectively, of FIG. 1;
  • FIG. 6 is a fragmentary vertical sectional view taken along the line 6-6 of FIG. 1;
  • FIG. 7 is an enlarged sectional view of a portion of thelens as seen in FIG. 6;
  • FIG. 8 is an enlarged sectional view of a portion of a lens as seen in FIG. 2; v
  • FIG. 9 is a diagram showingthe down spread pattern of the light beam projected through the lens of the present invention.
  • FIG. 10 is a transverse sectional view of a traffic light housing incorporating thelens of the present invention.
  • FIG. 1 1 is a graph showing a typical horizontal spread pattern of the light projected through the lens.
  • a traffic signal projectorassembly 40 This assembly is comprised of a housing 42, a parabolic reflector 44 mounted in the housing, a light bulb 46 within the parabolic reflector and with its filament 48 at the focus of the reflector 44, and a lens and cover plate 10 which is sealed at its circumference 22 to the reflector 44 and housing 42.
  • the parabolic reflector 44' serves to direct the light from the filament 48 in a generallyhorizontal beam and the lens 20 bends or diverts this beam into the desired spread pattern.
  • FIG. 11 illustrates that the major portion of the projected beam is directed substantially straight ahead along the predetermined downward inclination with an illumination of at least 1,000 candle power a being provided in the range of 7% on either side of the downwardly directed path. As the observation point is shifted to the right or left of the axis the illumination required decreases so that at 17% an illumination of 500 candle power is provided.
  • the lens 10 designed to achieve the desired spread pattern is illustrated in FIGS. 1 through 9.
  • the lens 10 has a smooth upper surface 12 in the form of a spherical segment, an inner surface 14, and a rim or lip 22.
  • the inner surface 14 of the lens is formed into a plurality of rectangular lenticular areas 18 and 20.
  • the lenticular areas 18 are curved while the areas 20 are flat surfaces.
  • the areas 18 and 20 are preferably arranged in horizontal rows 22 and 24 and cover the entire inner surface 14 of the lens.
  • the lenticular areas of adjacent rows 22 and 24 are staggered-or offset relative to one another.
  • the lenticular areas form a brick-work like or mosaic pattern on the inner surface 14 of the lens.
  • the curved lenticular areas 18 predominate in the lens, as the flat lenticular areas 20 are preferably provided only in alternate ones of the rows and only as every fourth member of such alternate rows.
  • a typical lens may have an overall diameter of 8% inches with the radius of curvature of the outer surface 12 being 7 inches.
  • the individual lenticular areas of such a lens may be approximately 0.25 inches wide and 0.125 inches high.
  • Preferably the lens thickness will be about 0.115 inches.
  • the curved lenticular elements 18 are curved in both the horizontal and vertical directions.
  • the horizontal curvature may have a radius of 0.48 inches and the vertical curvature, a radius of 0.25 inches.
  • the curved elements 18 are inclined, with their lower edges being further from the outer surface 12 of the lens than are their upper edges.
  • the flat elements 20 are also inclined in the same manner.
  • the flat surfaces 20 are inclined from the imaginary spherical surface 30 by an angle of between 2 and 10, but preferably approximately The surfaces of these elements 20, however, are flat in both the horizontal and vertical directions.
  • the midpoints 26 of the upper edges of the curved lenticular areas 18 and the midpoints 28 of the upper edges of the flat lenticular areas 20 lie on a common spherical surface concentric with the outer surface 12 of the lens.
  • the contours of the lenticular elements 18 and the inclinations of these surfaces shown in the drawings are those which provide the desired spread pattern for a polycarbonate lens.
  • the contour of each lenticular area 18 is determined from the consideration of the desired deflection of the projection axis, horizontal axis of the lens and parabola assembly, the desired spread of the projected beam, and the index of refraction of the lens material.
  • the preferable material for forming the lens is polycarbonate. This material, which can be molded into the proper shape, has greater resistance to breakage, scratching and the like than any other material known at this time.
  • the thickness of the lens is chosen for ease of molding, and strength of the part. Polycarbonate is available in standard colors.
  • the lens is formed of polycarbonate by a molding process.
  • the mold for forming the inner surface 14 of the lens may be formed of a stack of steel plates, each plate being of a thickness equal to the height of one row of lenticular areas. Since all of the curved lenticularareas 18 are of the same contour the mold plates may be formed to the desired contour by the use of an end mill cutter having a rounded or uniform radius contour. Likewise, the mold portions for the flat lenticular areas 20 may be formed on the mold face by the use of end mill cutters with flat end surfaces. This method assures a uniformity of the contours of the lenticular areas throughout the lens as well as substantially reducing the cost of preparing the mold.
  • the lower edges 32 of the lenticular elements are inclined slightly from the horizontal so as to provide sufficient draft to permit the cast lens to be removed from the mold. A typical angle of draft is 3.
  • the curved lenticular areas 18 serve both to direct the light downwardly from the horizontal axis of the lens and projector assembly and to direct the light into a diverging pattern to provide adequate illumination within the entire range of an observer of a signal, i.e., a pedestrian or a vehicle near the light and to one side or the other of its axis.
  • the inclination of the curved lenticular areas 18 from the spherical reference provides the downwardly directing action while the curved surface 18 provides for the diverging pattern.
  • the total downspread of the light beam by the curved segments is shown in FIG. 9.
  • the curvature and inclination of the lenticular areas 18 will deflect a light beam parallel to the horizontal downwardly by an angle of 12.5".
  • the lamp filament is not a true point light source located at the focus of the paraboloid, an additional spreading of the light beam will result. This can be seen from FIG. 10 when the spread resulting from the filament is indicated at 50.
  • the maximum downspread from the horizontal through the curved segments or lenticular areas 18 of the lens is 225.
  • the flat lenticular areas serve to direct the portion of the light beam passing through these areas downwardly at a slight angle normally 2% from the horizontal and generally in the central portion of the range of an observer of the signal, thus providing the desired higher illumination at the straight ahead position, but still allowing sufficient illumination to occur in side areas. 1
  • the lens as described hereinabove will meet the standards set up by the Institute of Traffic Engineers. All of the lenticular elements are tilted to project the light downwardly. Most of the elements, (ie., the areas 18 of which there are about 10 times as many as the flat areas 20) are curved in both the vertical and horizontal direction, in order to spread the light to a pedestrian; as well as to a motorist; for example, the pedestrian may be located as far as l7 below the projector axis of the traffic light. Drivers of vehicles may be to one side of the light, as may be pedestrians and therefore areas 18 are curved in the horizontal plane as well.
  • a lens for a traffic light signal comprising:
  • first lenticular elements formed on one surface of the body portion, the first lenticular elements being curved in both the horizontal and vertical directions;
  • the lens according to claim 4 wherein there is a greater number of said first lenticular elements than second lenticular elements, and said lens is made from a polycarbonate material.
  • a traffic light signal lens having a smooth outer surface and an inner surface formed into a plurality of horizontally parallel rows of lenticular elements, the lenticular elements being of two types, the first type of lenticular elements being curved in both the horizontal and vertical directions and the second type of lenticular elements being flat.
  • a traffic light signal lens havinga smooth outer surface and an inner surface formed into a plurality of lenticular elements, the lenticular elements being of two types, the first type of lenticularelements being curved in both the horizontal and vertical directions and the second type of lenticular elements being flat, both said types of lenticular elements being rectangular and having a greater length than height, and said lenticular elements being arranged in horizontally extending rows with the elements of adjacent rows being offset in a brick-work like pattern.
  • a traffic light signal lens having a smooth outer surface and an inner surface formed into a plurality of lenticular elements, the lenticular elements being of two types, the first type of lenticular elements being curved in both the horizontaland vertical directions and the second type of lenticular elements being flat, said lenticular elements being tilted to provide a maximum point of illumination along an axis inclined by an angle of between 1 to 10 from the horizontal.
  • each lens is formed with a tappered edge surface to permit molding of the lens from said polycarbonate material.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Non-Portable Lighting Devices Or Systems Thereof (AREA)
US00116386A 1971-02-18 1971-02-18 Traffic signal lens Expired - Lifetime US3798445A (en)

Applications Claiming Priority (1)

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US11638671A 1971-02-18 1971-02-18

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AR (1) AR192345A1 (pt)
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CA (1) CA996909A (pt)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4042818A (en) * 1975-04-01 1977-08-16 The Lucas Electrical Company Limited Lamp assembly
US4274217A (en) * 1978-07-25 1981-06-23 Sanyo Electric Co., Ltd. Display device

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2068805A (en) * 1935-02-04 1937-01-26 Corning Glass Works Cover glass
US2846568A (en) * 1954-04-09 1958-08-05 Gen Motors Corp Headlight lens
US2907249A (en) * 1956-10-05 1959-10-06 Electro Seal Corp Lens for signal lights
US3222516A (en) * 1963-06-24 1965-12-07 Lancaster Glass Corp Lenticulated lens for traffic light
US3383676A (en) * 1963-02-14 1968-05-14 Robert I. Nagel Lenticular signal lens having a smooth outer surface
US3425329A (en) * 1965-07-09 1969-02-04 Prontor Werk Gauthier Gmbh Photographic self-cocking shutter with electronic shutter speed control
GB1158691A (en) * 1967-04-01 1969-07-16 Prontor Werk Gauthier Gmbh A Camera Shutter having an Electronic Timing Device

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2068805A (en) * 1935-02-04 1937-01-26 Corning Glass Works Cover glass
US2846568A (en) * 1954-04-09 1958-08-05 Gen Motors Corp Headlight lens
US2907249A (en) * 1956-10-05 1959-10-06 Electro Seal Corp Lens for signal lights
US3383676A (en) * 1963-02-14 1968-05-14 Robert I. Nagel Lenticular signal lens having a smooth outer surface
US3222516A (en) * 1963-06-24 1965-12-07 Lancaster Glass Corp Lenticulated lens for traffic light
US3425329A (en) * 1965-07-09 1969-02-04 Prontor Werk Gauthier Gmbh Photographic self-cocking shutter with electronic shutter speed control
GB1158691A (en) * 1967-04-01 1969-07-16 Prontor Werk Gauthier Gmbh A Camera Shutter having an Electronic Timing Device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4042818A (en) * 1975-04-01 1977-08-16 The Lucas Electrical Company Limited Lamp assembly
US4274217A (en) * 1978-07-25 1981-06-23 Sanyo Electric Co., Ltd. Display device

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Publication number Publication date
AR192345A1 (es) 1973-02-14
BR7200734D0 (pt) 1973-06-05
CA996909A (en) 1976-09-14

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Owner name: WICKES MANUFACTURING COMPANY, A CORP. OF DE.,MICHI

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:GULF & WESTERN INDUSTRIES, INC., FORMERLY GULF & WESTERN INDUSTRIES, INC.,;REEL/FRAME:004821/0437

Effective date: 19871215

Owner name: EAGLE SIGNAL CONTROLS CORP., A CORP. OF DE.

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:WICKES MANUFACTURING COMPANY, A DE. CORP.;REEL/FRAME:004821/0443

Effective date: 19871218

Owner name: WICKES MANUFACTURING COMPANY, 26261 EVERGREEN ROAD

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:GULF & WESTERN INDUSTRIES, INC., FORMERLY GULF & WESTERN INDUSTRIES, INC.,;REEL/FRAME:004821/0437

Effective date: 19871215