US2177216A

US2177216A - Vehicle head lamp

Info

Publication number: US2177216A
Application number: US132531A
Authority: US
Inventors: Ernest A Howard; Kenneth D Scott
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1937-03-23
Filing date: 1937-03-23
Publication date: 1939-10-24
Anticipated expiration: 1956-10-24

Description

1939. E. A. HOWARD El AL 2,177,216

VEHI CLE HEAD LAMP Filed March 23, 1937 3 Sheets-meet 1 SI! Inventors:

w Ernest A. Howard, Kenneth D. Scott,

y ZW Their" Att orney 06L 1939- E. A. HOWARD ET AL VEHICLE HEAD LAMP 3 Sheets-Sheet 2 Filed March 25, 1957 Their Attcrney.

Oct. 24, 1939. HOWARD AL 2,177,216

I VEHICLE HEAD LAMP Filed March 23, 1937 3 Sheets-Sheet 3 10 v Inventors Ernest A. Howard, v Kenneth D. Scott;

T heir Attorn y- Patented Oct. 24, 1939 1 UNITED STATES PATENT OFFICE VEHICLE HEAD LAMP Application March 23, 1937, Serial No. 132,531

3 C. (CL 240-413) Our invention relates to vehicle headlights, and more particularly to light directing elements or lenses therefor. Still more particularly, our invention pertains to a design of lens adapted to 5 produce an asymmetric or country meeting beam for use while two cars are approaching one another, which beam will adequately illuminate the right side of the highway and will be characterized by the absence of glare, due primarily to a sharp light cut-off in such beam to the left and above the horizontal.

Our design of lens has been developed in conjunction with, and is particularly applicable to vehicle headlights of the reflector lamp type such as is described and claimed in co-pending application Serial No. 68,713, Daniel K. Wright, filed March 13, 1936. In lamps of this, typ a" single filament or concentrated light source is accurately positioned at the focal point of the parabolic reflector portion of the lamp, thereby resulting in the projection of a powerful and efflcient beam .of light. When such a lamp is used to project only one type of beam, such as a country meeting, country driving or city driving beam, the

lens with which such lamp is equipped can be so designed as to produce the most efiicient beam of the single type desired.

An asymmetric or country meeting beam should comprise a high intensity portion extending straight down the right side of the highway only, and formed with sharply defined vertical edges, together with gradually tapering side portions having a sharply defined top surface located a degree or two below the horizontal to thereby insure against the projection of upwardly directed rays oflight on the left side of the highway, which rays impair the vision of approaching drivers. To further insure against glare, the top surface of the high intensity portion should also be kept below the horizontal, although only slightly so. The major portion of the light making up-the'beam shpuld be disposed on the right side of the highway where it is needed to increase the illumination thereof. This is desirable in order that the decrease in the driver's visibility of the right side of-the highway, occasioned by the glare of the approaching headlights, may be counteracted or equalized by the increased-lllumination of such right side, thereby'maintaining the drivers normal degree .of visibility of the 1 same. Furthermore, since the headlights of the approaching vehicle sufficiently illuminate the 7 left side of the highway, very little light need be 55 projected towards such side, so that the major portion of the light may be utilized to good advantage on the right side of the highway.

One object of our invention is the provision of a headlight lens which will produce an eflicient asymmetric or country meeting beam fulfilling 5 the above-mentioned requirements. A further object of our invention is the provision of a headlight lens which, when mounted on a headlight the reflector axis of which is directed several degrees below the horizontal plane passing through 10 the focal point of the reflector and several degrees to the right of the vertical plane passing through said focal point parallel to the longitudinal axis of the vehicle, will direct a concentrated or high intensity beam to the left of and 15 above the reflector axis yet to the right of said vertical plane and below said horizontal plane.

Another object is the provision of a headlight lens which, when mounted on a headlight the reflector axis of which is directed as above stated, go will direct the major portion of the light emanating therefrom down the right side of the roadway to better illuminate the same.

Still another object of our invention is the provision of a headlight lens which, when 35, mounted on a headlight the reflector axis of. which is directed as above stated, will produce an asymmetric or country meeting beam characterized by a sharp light cut-ofl above the horizontal plane passing through the reflector focal 30 point, and to the left of the vertical plane passing through said focal point parallel to the longitudinal axis of the vehicle. 4

A further object is the design of a headlight lens which utilizes the rays of light passing 35 I through only the top, bottom and side areas thereof for the production of the high intensity portion of the beam.

A still further object of our invention is the provision of a headlight lens having a plurality 40 of'upward and left bending prisms formed thereon for the purpose of bending the rays of light passing therethrough upward and to the left to thereby minimize the source of glare in the lens itself by the elimination of those refractory faces and corners thereon which normally produce glare.

Another object is the provision of a downwardly bending prism at the central area of a headlight lens for the purpose of depressing the rays of light passing therethrough to thereby illuminate that portion of the highway immediately in front of the vehicle, and also to eliminate the glare normally emanating from such center area by inaccurately disposed filaments.

Still another object is the provision of divers vertically extending, horizontal light spreading flutes so situated on the lens and sograded in degree of spread as will provide the desired amount of horizontal spread 'for the various beam portions making up the composite asymmetric or country meeting beam.

Other objects and advantages of our inventionwill be apparent from the following description of an embodiment thereof and from the accompanying drawings, in which:

Fig. 1 is a, horizontal sectional view of a refiector lamp of the type disclosed in the previously mentioned co-pending application Serial No.

68,713, equipped with a lens made in accordance with our invention; Fig. 2 is a' diagrammatic view showing the manner in which a reflector lamp equipped with'our country meeting lens may be of light striking the various portions of the same are refracted thereby; Fig. 5 is a front elevation of a country meeting lens comprising our invention; Figs. 6, 7, .8 and 9 are vertical sectional viewstaken on the lines d-d, l?, d-t, and 9 respectively of Fig. 5; Figs. 10, 11 and 12 are horizontal sectional views taken on the lines in Fig. 1, the reflector axis of which is directed i@it, H-ll l,'and i2-i2 respectively of Fig. 5;

and Fig. 13 is a .view showing the beam pattern produced by our country meeting lens when mounted on a reflector lamp of the type shown approximatelyfi degrees below the horizontal plane passing through'the reflector focal point and approximately 5 degrees to ,the right of the vertical plane passing through the said focal point parallel tothe longitudinal axis of the vehicle.

Referring to the drawings, there is shown in Fig. 1 a reflector lamp comprising a lens it, in accordance with our invention, sealed at it to a preformed reflector portion it in the manner described in the previously referred to co-pending application. The said reflector portion i2 is made of pressed glass, the interior surface 63 of which is preferably of parabolimial shape and is covered with a coating M constituting a reflecting surface. A concentrated light source comprising a horizontally disposed bar filament iii, similar to that disclosed in U. S. Patent No. 2,012,806, Brown et al., is mounted within the lamp by lead wires It, terminal members Ill, and metal cups it, and is accurately positioned at the focal point of the reflector surface 84. The greater accuracy with which the pressed glass paraboloidal interior surface H can be formed over the conventional stamped metal reflectors, together with the accurate disposition of the concentrated light source 45 at the focal point of the reflector surface I 4, results in the projection of a powerful and efficient beam of light.

When such'a lamp is utilized for the projection of a single type of beam only, such as an asymmetric or country meeting beam, the lens canbe so designed as to produce the proper distribution of the light rays for such' be'amalone. Fig. 2

illustrates diagrammatically one manner in which a plurality of reflector lamps of the type described above, each equipped with a different lens designed to produce a different type of beam, may be mounted in a. holder l9. Lens I0 is a country meeting lens made in accordance with our invention, while lens 20 is adapted to produce a. country driving beam, and lens 2| a city driving beam. The lens 20 maybe'of the type shown and claimed in our application Serial No. 132,530 of even date, and lens 2| may be of the type shown and claimed in our application Serial No. 132,532 of even date. Although we have shown all three lamps mounted in a single holder, they may, if desired, be separately mounted, or grouped in a variety of ways. Thus, the country meeting lamps may be mounted on or inthe front fenders of an automobile to better indicate the width of the car to approaching drivers, while the country and city driving lamps may be grouped together nearer the center of the car. I

Referring to Fig. 5, the lens it comprises a pluralihr of substantially horizontal sections, c0n= sisting of a top section 22, a bottom section 23, a center section 2.6, and upper and lower

intermediate sections

25, 25. The top and

bottom sections

22, 23 each comprise a central area A and side areas B. The

intermediate sections

25, 25 each comprise a central area 0, primary intermediate areas D, secondary intermediate areas E, and side areas B. The center section 26! comprises a central area G, intermediate areas F, and side areas B. Each of the sections 22," 2%], 2d and 25 has a plurality of vertically extending light spreading flutes formed on the rear surface of the lens, certain of which are of diflerent degrees of spread. In addition, certain portions of each of said sections are formed with either'upwardly or left bending prisms, or both, on the rear surface of the lens, while the central portion oi the center section 25 is formed with both a downwardly and left bending prism on the rearsurface of the lens.

1 In the manufacture of lenses formed with prisms thereon, the ends or extremities of such prisms must be provided with a slight amount of draft to permit removal of the lensfrom the mold. The bases of the prisms always have rounded corners which constitute small secondary lenses which direct the rays of light striking the same in a direction opposite to that of the rays refracted by the prism itself.

It has been customary heretofore in the design of lenses for the production of asymmetric beams to provide the same with either downward or right bending prisms, or both, for the purpose of directing the rays of light passing therethrough downward and to the right to thereby prevent such rays from striking the eyes of approaching drivers. The previously described corners direct the rays of light striking them upward in the case of a downward bending prism, and to the left in the case of a right bending prism. Thus these corners constitute sources of light in the lens itself which create a considerable amount of glare. By providing our country meeting lens with upward and left bending prisms we have eliminated such sources of light and resulting glare in the lens itself.

' Referring to Fig. 3, showing an enlarged view of one of the upwardly bending vertical prisms p formed on the rear surface of our lens, the projected rays of light p striking the prism itself are refracted upwardly, as at 12, while the projected rays of light swhich strike the prism base comer s are directed downwardly, as at 8''. Thus] there are no upwardly directed rays of light emanating from the prism base corner 8 which would be apt to strike the eyes of approaching drivers. Likewise, in the enlarged view in Fig. 4 5 of one of the left bending vertically extending prisms p formed on the rear surface of our lens, the projected rays of light p striking the prism itself are refracted to the left, as at p, while the rays of light 3 which strike the prism base -'corner s are refracted to the right, as at s". Thus there are no leftwardly directed rays of light emanating from the base corner s and projecting onto the left side of the road, where they would be apt to interfere with the'vision of approaching drivers. By simply aiming the reflector axis the proper amount below the horizontal plane passing through the reflector focal point, and to the right of the vertical plane passing through such focal point parallel to the longitudinal axis of the vehicle, the upwardly and leftwardly directed rays 9" refracted by the upward and left bending prisms respectively can be made to project substantially horizontally and straight down the right side of the roadway so as not to shine into the eyes of approaching drivers. As

shown in the beam pattern (Fig. 13) of our country meeting lens, we preferably locate the aiming point a: of the reflector approximately 3 degrees below the horizontal plane H--H passing through the reflector focal point, and 5 degrees to the right of the vertical plane V-V passing o through said focal point parallel to the longitudinal axis of the vehicle.

The high intensity portion of an asymmetric or country meeting beam should be relatively narrow both in vertical and horizontal spread. To obtain a beam of narrow vertical spread the light rays making up the same must, of necessity, be taken from those portions of the reflector projecting the smallest images of the filament or light source, which images are more easily controlled than the larger ones. The smallest images of the light source will be projected by those portions of the reflector furthest from such light source. These small imagesareprojectedthrough those portions of the lens immediately adjacent the periphery thereof. It is for this reason that the rays of light passing through the areas A and B (Fig. 5) of the lens l0, comprising the top and

bottom sections

22 and 2 respectively, and the extreme outer or side portions of the center and

intermediate sections

24 and 25 respectively, are utilized to make up the high intensity portion of the composite country meeting beam.

Referring to Figs. 6 to 9 inclusive, the top and bottom areas A- are each provided with an upwardly bending vertical prism 26, preferably of 4 degrees, formed on the rear surface of the lens, while the areas B are each provided with an m upwardly bending vertical prism 21, preferably of 3 degrees, likewise formed on said rear surface. In addition, the said areas A and B are provided with left bending vertically extending prisms 28, preferably of 4 degrees, formed on the rear sur- 155 face of the lens, as indicated in Figs. 10, 11 and 12. Inasmuch as the horizontal spread of the high intensity portion of the asymmetric or country meeting beam should be relatively small, the degree of spread of the flutes included within the 7 areas A and B should be very-little. Accordingly each area A comprises a plurality of vertically extending horizontal light spreading flutes 29, preferably of 1 degree spread, formed on the rear surface of the lens, while each area B comprises a plurality of similar flutes '30, but preferably of 3 degree spread, also formed on said rear surface. The beams produced by the areas A and B, and indicated at A and B in the beam pattern (Fig. 13), together comprise the high intensity portion of the composite asymmetric beam. As is apparent from the beam pattern, this high intensity portion A, B is directed substantially entirely above and to the left of the reflector axis or aiming point a: by the upward bending prisms 26, 21 and left bending prisms 28 formed on the lens within the areas A and B thereof. However, by aiming the reflector axis the proper distance below the H line and to the right of the V line, as indicated at :c, the high intensity beam portions A, B are so directed as to lie both below the H line and to the right of the V line, thereby preventing such beam portions from striking the eyes of approaching drivers. Thus when the aiming point a: is located approximately 3 degrees below the H line and 5 degrees to the right of the V line, the top surface of the beam portion A will lie a small fraction of a degree below the H line while that of the beam portion B will lie approximately /2 degree below the same. Also, the left edges of both beam portions A, B will lie approximately degree to the right of the V line.

The widespread graduated-intensity portion of our asymmetric beam, indicated at C, D and E in Fig. 13, should be directed so that the top surface thereof is maintained approximately 2 degrees below the H line in order to insure against any rays of light projecting upward into the eyes of approaching drivers, which condition might ordinarily result from either inaccurately disposed fllaments or from loading variations or longitudinal rocking motions of the vehicle. We have found that 2 degrees is suflicient to prevent projection of any rays, included in the portions C, D and E, above the H line in practically all instances of inaccurately disposed .fllaments, loading variations, or longitudinal rocking motion. To accomplish the above object of our invention, it is quite important that the top surfaces of the widespread graduated-intensity portions C, D and E be positively maintained at the above stated level of 2 degrees below the H line.

Consequently, the areas C, D and E of the intermediate sections 25 of the lens are utilized to produce the widespread portions C, D and E of the composite beam for the reason that the images projected therethrough are the next in smallness of size and easiness of control to those projected through the areas A and B.

Referring to Fig. 11, the central area C comprises a plurality of vertically extending horizontal lightspreading flutes 3|, preferably of 10 degree spread, formed on the rear surface of the lens. The primary intermediate areas D each consist .of' a single similarly disposed flute 32 preferably of 15 degree spread, while each of the secondary intermediate areas E comprises a pair of flutes 33 preferably of 40 degree spread. Each area E is also provided with vertically extending left bending prisms 3!, preferably of 15 degrees, formed on the rear surface of the lens. Since neither of the areas C, D and E is provided with vertically bending prisms, the beam portions C, D and E produced .by these areas are symmetrically disposed about the horizontal plane passing through the reflector axis. Aiming the reflector downward, at the 3% degree angle previously referred to, lowers the top surfaces of the beam portions C, D and E to the desired level of 2 degrees below the H line tothereby form a sharp light cut-off above such level. The beam portions C and D are also disposed symmetrically about the vertical plane passing through the reflector axis, but the vertically extending left bending prisms 34 formed in the areas E refract the light rays passing therethrough to the left, so that the beam E is asymmetrically disposed about said vertical plane. The resulting extended left portion ofthe beam E" furnishes the smaller amount of illumination required for the left side of the roadway when meeting another vehicle.

To further illuminate the right side of the roadway, ,and especially the extreme right portion thereof up to the horizontal line H--H (Fig. 13) so as to reveal banks, walls or other objects bordering such roadway, the portion F of the beam is provided by the intermediate areas F of the center section 24. Though the images projected through the areas F are quite large and difficult to control, so thata slight inaccuracy in the disposition of the light source at the reflector focal point would be apt to cause upwardly directed rays of light, such a condition would not be overly objectionable for the very reason that such rays are directed onlyon the right side of the roadway where they would not interfere with the vision of approaching drivers. Each of the areas F comprises a pair of vertically extending horizontal light spreading flutes 35. (Fig. 12) preferably of 2 degree spread and formed on the rear surface of the lens. In addition, said areas F are each provided with an upwardly bending vertical prism- 36, preferably of 2 degrees, likewise formed on the rear surface of the lens. As is apparent from the beam pattern shown in Fig. 13, the beam portion F produced by the areas F is disposed symmetrically about the vertical plane passing through the reflector axis :0, but, due to the upwardly bending prisms 36, lies substantially above the horizontal plane passing through such axis, so that the top surface of said beam is located only one: ha degree or so below the H line.

Since the images projected through the remaining area G of the lens are the largest and most difficult to control, the rays of light passing through the said area G are utilized to produce the sideward and downward graduatedintensity portion G of the composite asymmetric beam; or in other words, the illumination immediately in front of the vehicle. To avoid the possibility of inaccurately disposed light sources causing upwardly directed rays of light to be projected through the area G, the latter is provided on the rear surfaceof the lens with a downward bending horizontally extending prism 31 graded from 1 degree at the top thereof to 8 degrees at the bottom. In this manner the rays of light passing through the area G are refracted or bent downwardly to positively insure against the projection of upwardly directed or glare rays therethrough. Section G is further provided with a plurality of vertically extending left bendlng prisms 38 of preferably degrees, and a plurality of vertically extending horizontal light spreading flutes 39, formed on the rear surface of the lens. As shown in the beam pattern in Fig. 13, the beam portion G is asymmetrically disposed about the reflector axis a, lying substantially below the horizontal plane passing through said axis, and having an extended portion to the left of the vertical plane passing through said axis to thereby illuminate the entire left side of the roadway, as well as the right side, immediately in front of the vehicle.

The following table lists the various areas into which our country meeting lens I0 is preferably divided, together with the corresponding degree of horizontal and vertical prism and horizontal light spread.

Referring to the beam pattern in Fig. 13, it will be observed that the left edge of the high intensity portion A, B, located approximately degree to the right of the V line, and the top surface of the widespread graduated intensity portions C, D and E', located approximately 2 degrees below the H line, together produce a sharp and distinct light cut-off to the left and above such points respectively. The entire area to the left of the V line and down to a level 2 degrees below the H line, constituting the likely location of the eyes of approaching drivers, is accordingly devoid of all light rays. This dark area thus prevents any strain on the eyes of approaching drivers.

The headlight lens described herein is adapted to produce a highly efficient asymmetric or country meeting beam. The said lens is simple in construction and positive in operation, and when mounted in a headlight, and especially in one of the type described herein, an accurately positioned and powerful beam of light is projected down the right side of the highway having a sharp light cut-oil to the left of the vertical line V and above a level 2 degrees below the hori- I zontal line H. In addition, our lens is adapted to direct the major portion of the light onto the right side of the highway where it is needed to offset or counteract the decrease in visibilityof such side caused by the glare of the approaching headlights. Furthermore, by the use of vupwardly and sidewardly bending prisms in our *lens, there are no undesirable light sources in such lens itself. i

It will be apparent to those skilled in the art that various changes may be made in the design of the lens as shown without departing from the spirit of the invention, such as altering the shapes of the sections and placing the flutes on the exterior or outer surface. Also, the light directing effect may be derived from a conflgurated refiector instead of from a lens.

What we claim as new and desire to secure by Letters Patent-of the United States is:

1. In a vehicle headlight for projecting down the road a beam of light having at the top thereof a high intensity portion on the right side of the road only with a sharply defined boundary at its left edge and at its top, the combination of a concave light-concentrating reflector, a lens therefor, and a light source in said reflector adjacent the focus thereof, said lens comprising sections extending across the top and bottom and sections located at each side, each of said sections having vertically extending prisms formed therein with their bases at the left and horizontally extending prisms with their bases at the top to produce the said high intensity portion at the top of the beam, said headlight being directed downward and toward the right a suflicient amount to cause the said portion of the beam to be projected to the right side of the road with its upper edge adjacent the horizontal, and said lens also having vertically extending flutes in other sections thereof arranged to produce a portion of the beam lower than said high intensity portion and extending across both sides of the road.

2. A lens for vehicle headlights divided into a plurality of horizontal sections extending across the width of the lens and consisting of top and bottomsections,upper and lowerintermediatesections, and a center section; said top and bottom sections and the side portions of the remaining sections containing vertically extending flutes of narrow light spread, vertically extending prisms of small refracting power with their bases to the left, and horizontally extending prisms with their bases uppermost, said prisms and flutes being arranged to produce ahigh intensity portion at the top and in the right side of the beam projected by the lens; the portions of said upper and lower intermediate sections between their said side portions containing vertically extending flutes of intermediate and wide light spread arranged to produce a band of light of wide lateral spread but narrow vertical spreadbelow the top of, and extending beyond the left edge of, the said high intensity portion of the beam; and the central portion of said center section comprising vertically extending flutes of wide light spread and a horizontally extending prism of large refracting power with its base lowermost to produce a band of light of wide lateral and vertical spread below the top of, and extending beyond the left edge of, the said high intensity portion of the beam.

3. A lens for vehicle headlights divided into a plurality of horizontal sections extending across the width of the lens and consisting of top and bottom sections, upper and lower intermediate sections, and a center section; said top and bottom sections and the side portions of the remaining sections containing vertically extending flutes of narrow light spread, vertically extending prisms of small retracting power with their bases to the left, and horizontally extending prisms with their bases uppermost, said prisms and flutes being arranged to produce a high intensity portion at the top and in the right side of the beam projected by the lens; the portions of said upper and lower intermediate sections between their said side portions containing vertically extending flutes of intermediate and wide light spread and vertically extending prisms of large retracting power with their bases to the left combined with said wide spreading flutes, said flutes and prisms being arranged to produce a band of light of Wide lateral spread but narrow vertical spread below the top of, and extending beyond the left edge of, the said high intensity portion of the beam; and the central portion of said center section comprising vertically extending flutes of wide light spread and a horizontally extending prism of large refracting power with its base lowermost A to produce a band of light of wide lateral and vertical spread below the top of, and extending beyond the left edge of, the said high intensity portion of the beam.

- ERNEST A. HOWARD. KENNETH D. SCOTT.