US1819283A

US1819283A - Head lamp lens

Info

Publication number: US1819283A
Authority: US
Inventors: Adiel Y Dodge
Original assignee: Individual
Current assignee: Individual
Priority date: 1928-04-04
Filing date: 1928-04-04
Publication date: 1931-08-18
Anticipated expiration: 1948-08-18

Description

Aug. 18, 1931. A; Y. DODGE HEAD LAMP LENS Filed Api'il 4, 1928 3 Sheets-Sheet l fivenfor':

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Aug. 18, 1931.

A. Y. DODGE 1,819,283

HEAD LAMP LENS 3 Sheets-Sheet 2 Filed April 4, 1928 22 *22 2/ 2o 20 2/ 3 /9 A2 /9 fiwenfor: 1719'. 5- %M Jig/62,71, i M

Aug. 18, 1931. A. Y. DODGE 1,319,233

HEAD LAMP LENS Filed April 4, 1928 s Sheets-Sheet s Patented Aug. 18, 1931 ADIEL Y. DODGE, OF SOUTH BEND, INDIANA new LAMP LENS Application filed April 4, 1928. Serial No. 267,173.

My invention relates to light controlling apparatus and more specifically to automobile headlight construction, and is an improvement over the construction described in my co-pending application, Serial No. 256,896, filed February 25, 1928.

It is a Well known fact in the art pertaining to head lamps that the position of the filament with relation to the focal point of the ordinary parabolic reflector may vary considerably in any direction due to permissible tolerances allowable for errors in manufacture, causing a convergence or divergence of the rays projected from the reflector depending on the position of the filament.

If the filament is exactly at the-focal point of a parabolic reflector, the reflected rays will be parallel. If in front of the focal point the rays will converge; if back of the focal point the rays will diverge; if above the focal point the rays in the rear of the focal plane will be projected downwardly;

and if below the focal point the rays in the rear of the focal plane will be projected upwardly, the degree of these angular projections being relative to the distance of the filament from the focal point of the reflector. It is also possible that the projected rays may converge or diverge in various angular directions as a resultant of the angular dis placement of the filament from the focal point with relation to the vertical and horizontal axes of the reflector. It is sometimes desirable to use a two filament bulb with the filaments on thevertical axis. With this bulb the driver can usewhichever one of the filaments desired, the upper filament being used to project the beam downwardly when another car is approaching.

In the head lamps using the ordinary lens, the resulting light pattern may be projected at various angles and distorted to such an extent as to cause glare.

In my invention I have overcome these objections and it has for one of its objects to provide an improved lens for use with a standard parabolic reflector and a two-filament bulb to produce a high or low beam of light, the resultant light patterns remalning substantially the same in both cases.

Another object is to provide an improved lens for automobile head lamps which will focus the rays of light to produce a desired pattern under various positions of the filament with relation to the focal point of the reflector.

Another object is to provide a lens for use with a standard parabolic reflector and a two-filament bulb in which sensitivity to the misplacement of the filament is minimized and which will produce a desirable light pattern in the upper beam, created by the lower filament, and substantially the same pattern in the lower beam, created by the upper filament, but descending at an angle of approximately from 2 to 2 degrees low-' er than the upper beams.

Further objects will appear from the description and claims.

In the drawings in which an embodiment of my invention is shown,

Figure 1 is an axial vertical section through a headlight construction incorporating my invention;

Fig. 2 is a diagrammatic view showing the light pattern as it appears on avertical screen at a distance from the head lamp;

Fig. 3 is a rear elevation of the lens;

Fig. 4 is a section substantially on the line 44 of Fig. 3;

FFig. 5 is a section on the line 55 of Fig. 6 is a diagrammatic View illustrating the vertical and'horizontal distribution of light rays; and

Fig. 7 is a diagrammatic view showing the vertical light distribution of the lens.

Referring now to the drawings in detail, the construction shown comprises a casing 1 usually of sheet metal and having a parabolic reflector 2 mounted therein. A lens 3 is mounted in front of the reflector and secured by anysuitable retainer such as the erably one above and one slightly below the focal point.

The lens 3 is so designed as to form a plurality of concavo-convex zones, A, B and C, of different spherical diameters and having-radii 7, 8, and 9, that portion of zone B enclosed within the heavy line 8w shown in Fig. 3, having a radius corresponding to line 8?), Fig. 1. The radius of the outer convex surface is shown by the line 10.

It will be noted that these radii are of different lengths but the centers are located in a central vertical plane.

A tubular reflecting shield 11 is mounted on a collar 12 formed integral with the lens, and that portion of the lens within the collar having a formation to assist in the proper distribution of light. This central portion 13 is convex on its inner face and is provided with a series of parallel vertical grooves 14, the cross-sectional radius of these grooves being relatively small to cause a Wide divergence of the light beam, a radius of approximately and a width of groove of being satisfactory. The collar and enclosed lens are of greater length horizontally than vertically which tends to give a lateral spread to the light rays. The

, inner surface of the tube causes the rays from the filament to be directed forwardly to the central lens which tends to bring them into a horizontal plane and to give them a lateral spread. The rear edge of this shield 11 is substantially circular and so positioned as to intercept practically all of the direct rays from the light source which would otherwise escape as a widely divergent beam through the lens 3. The shield 11 may be cut away if desired, as shown at 15, to permit a certain amount of light to escape through the lens 3 to illuminate the side of the roadway.

In order to provide the desired light distribution, the lines dividing the zones A, B, andC, are curved instead of being horizontal. The line 16 between the intermediate and upper zones is concave upwardly from the middle portion of the zones to the edge of the lens. The line 17 is concave downwardly from the middle of the zones totheedge.

The moderately wide divergence of the beam through the upper zone A and the lower zone C is accomplished by providing the inner face of these zones with a series of parallel vertically extending concave grooves 18 having a cross-sectional radius relatively small. It has been found satisfactory to make these grooves in width and with radius.

The slight divergence of the powerful beam through the intermediate zone, B is accomplished by providing this zone with a series of parallel vertically extending

grooves

19, 20, 21, 22, and 23, having comparatively large cross-sectional radii.

In practice I have found a desirable light pattern to be obtained by having the central grooves 19 approximately radius and in width, the grooves 20 approximately radius and in width, grooves 21 approximately 2 radius and 7 in width, grooves 22 approximately 1% radius and wide, and the grooves 23 relatively small in width and radius.

It will be noted that, due to the length and position of centers of the radii 7, 8, 8b and 9 of the three zones, and the convex curvature of the outside surface of the lens, the lens is of constantly increasing thickness from the top to the bottom of each zone on any vertical section, and that the thickness at the top of each zone is less than at the bottom of the adjacent zone.

This is for the purpose of producing the desired vertical arrangement of the light pattern as illustrated in Fig. 2 in which the area 24 indicates the area of highest light intensity, 25 an area of intensity approximately one-third of that at 24, area 26 an intensity about one-sixth of 24, and 27 about one-tenth the intensity of 24. The area 28 is caused by stray rays of very low intensity.

It will be noted from this diagram that it is desirable to maintain the area of highest intensity near the top, and the areas 24, 25, and 26 are superimposed on the area 27. The area 24- having the highest intensity is produced from the beam through the

grooves

21 and 22 of the middle zone B. Area 25 is produced through the

grooves

19 and 20 of zone B. Area'26 is produced from the upper and lower zones A and C, and area 27 is produced.- by stray rays in general from zones A and B. and through the tubular shield 11. The main rays passing through the shield and lens formation 13 fall on the area 25 and 26, the stray rays spreading widely, covering area 27 and fading out into pattern 28. i

It will be seen from studying the action of the rays projected from a parabolic reflector with various positions of the filament, that it is desirable to tilt the rays coming from the upper portion of the reflector downward, and thatthose rays coming from the most remote upper portion should be tilted downwardly to a greater extent than those coming from thecenter, and furthermore, the degree of tilt should constantly decrease from the top to the center.

It is also desirable to tilt the rays coming from the lower portion of the parabola downward, and those rays coming from the lowermost portion should be tilted downwardlyito a greater extent than those coming from the center, the degree of tilt uniformly increasing from center to bottom.

In order that the beams from the zones should overlap each other and form the de-' sired light pattern, the beams are tilted as illustrated diagrammatically in Fig. 7. The degree of tilt of zone A at the border line between zones A and B as indicated by line 29 is greater than the tilt of zone B at that border line, as indicated by line 30, and further, the tilt of the beam from the border line of z ne B at 31 is greater than the tilt :3); zone C at that line, as indicated by line The desired tilt of the rays is accomplished bya constantly varying thickness of lens in each zone on any vertical section. This variation of thickness or tilt of lens in each zone is not in steps but in a varying sweep to match the action of rays caused by misplacement of the filament, and successfully refocuses the ascending rays from the upper and lower portion of the parabolic reflector due to a back or front position of the filament with relation to the focal point, and causes them to fall in correct relative position to the beams of high intensity. The angular rays from the upper part of the reflector will fall on the pattern of high intensity due to 'a front focus, and under the pattern of high intensity due to a back focus.

The upper border of zone A will never ascend above the high intensity pattern of zone B and varying from this to barely overlapping the lower border pattern from zone The pattern from zone C varies according to the Various positions of filament, so that its upper border falls under the pattern from zone B and coinciding therewith to the position under the pattern from zone A.

The angle of the ascending rays from the reflector caused by misplaced filament varies with their location relatively to the vertical and horizontal axes of the reflec tor; that is, rays on the transverse horizontal axial plane are substantially horizontal while those lying on the vertical axial plane have the maximum amount of ascension or descension. Therefore, in order to take care of these conditions, the degree of downward tilt of the rays varies across the horizontal sections of the lens having the greatest degree of tilt at the center-most portion, this being true of any horizontal section, and the least amount of tilt at the outermost portion, and this tilt should be in constantly increasing ratio toward the center.

This is illustrated by the

lines

33, 34, and 35 representing the rays on a horizontal plane through the lens 3, the ray 33 being on the vertical central plane, the ray 35 from a remote point on a horizontal plane,

- and the ray 34 from a point intermediate 33 and 35. This is just the opposite condition to that in the vertical sections. The tilt or downward angular PI'OjGOtlOIl, de-

creases in the vertical sections toward the center as shown by the'rays represented by the lines 33a, 3312, 330 and 3312. A

If the lens betheoretically divided int any number of vertical sections, the rays from the central vertical section has more tilt than the rays on a horizontal line at any other vertical section, and each subsequent Vertical section more remote from the center has less tilt than the vertical section next adjacent and toward the center.

While I have shown only one embodiment of my invention it is obvious that modifications may occur to those skilled in the art, and I desire, therefore, that my invention be limited only by the scope of the appended claims and by the prior art.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. An automobile headlamp construction comprising an electric lamp bulb, a concave reflector in which said bulb is mounted for directing the rays of light which fall thereon substantially parallel to the axis, means for intercepting and redirecting the cone of those light rays from said bulb which do not fall on the concave reflector and which would otherwise pass directly out through the open front of the reflector, said. intercepting and redirecting means having provisions for effecting a materially greater spread of said light'cone laterally than vertically, said intercepting and redirecting meansnot extending laterally or upwardly materially beyond the confines of a cylindrical surface tangent to the light bulb and coaxial with the reflector whereby the beam from the concave reflector is not materially interfered with, and said intercepting and redirecting means comprising a funnel having its rear edge lying substantially in the surface of said cone'of rays and its front portion flat vertically and elongated laterally, and a lens portion adjacent the front portion of said funnel having a greater refractive power laterally than vertically.

2. An automobile headlamp construction comprising an electric lamp bulb, a concave reflector in which said bulb is mounted for directing the raysof light which fall thereon substantially parallel to the axis, and means for intercepting and redirecting the cone of those light rays from said bulb which do not fall on the concave reflector and which would otherwise pass directly out through the open front of the reflector, said intercepting and redirecting means having provisions for effecting a materially greater spread of said light cone laterally than vertically, said intercepting and redirecting means not extending laterally or upwardly coaxial with the reflector whereby the beam from the concave reflector is not materially interfered with, said intercepting and redirecting means comprising a funnel having its rear edge lying substantially in the surface of said cone of rays and its front portion flat vertically and elongated laterally, said reflector being provided with an inwardly concave outwardly convex glass cover extending across the front thereof, a substantial portion of said funnel being within said concavity, whereby a long funnel is provided.

3. In an automobile headlight construction, the combination with a concave open front reflector and redirecting means for redirecting forwardly and toward the axis of the reflector a substantial portion of the rays from the lamp which do not fall on the reflector and which would otherwise pass directly through said open front, of a lens in front of said redirecting means for receiving and again redirecting said redirected rays whereby the rays which do not fall on the reflector may be utilized and given the desired direction without materially interfering with the rays reflected from said reflector, said first redirecting means having provisions for effecting more concentration vertically than laterally, and said lens having provisions for causing lateral divergence of the rays passingltherethrough.

4. In an automobile eadlight construction, the combination with a concave open front reflector and means for concentrating the rays from the lamp which do not fall on the reflector and which would otherwise pass directly through said open front, of a lens in front of said concentrating means for receiving and redirecting said concentrated ra s whereby the rays which do not fall on t e reflector may be utilized and given the desired direction without materially interfering with the rays reflected from said reflector, said concentrating means having provisions for effecting more concentration vertically than laterally, and said lens being laterally elongated and having vertically extending lens formations for causing lateral divergence of the rays passing therethrough.

In witness whereof, I have hereunto subscribed my name.

ADIEL Y. DODGE.