US1950978A - Lens for head lamps - Google Patents

Description

March 13, 1934. RgN FALGE ,950,978

LENS FOR HEAD LAMPS Filed Dec. '7. 1932 I x 7 xzx//z WWW/ Sme YIM@ &Hot/144430 Patented Mar. 13, 1934 -LENS FOR HEAD LAMPS Robert N. Falge, Anderson, Ind., assignor, by mesne assignments, to General Motors Corporation, Detroit, Mich., a. Corporation of Delaware Application December 7, 1932, Seriai No. 646,()67

2 Clams. (Ci. 240-414) This invention has to do with lenses especially ilute has an s-shaped outer face with a porsuch as were employed in headlamps of the design tion 11 oi" the face between the edges of the flute described and claimed in the application of approximately parallel to the opposite face of Charles E. Godley and Robert N, Falge, Serial No. the lens. This is further indicated in Figure 3 539518, filed May 23, 1931. where ray 14: is shown passing through the por- In that application there are disclosed several tion 11 of the fiute without being altered in dheadlighting systems in which each lamp Supplies rection, while rays 16 and 18, passing through the light at the top of the beam on one side only, the edges of the ute, are directed sharply tothe combined beams from the two lamps proward the right. Intermediate rays will be bent 10. ducing a high beam having a substantially horiin amounts varying between these limits. With 65 zontal cutoff at the top. By depressing the beam this design rays 14 will therefore form the left from one lamp a passing beam is obtained which boundary of the pattern. The advantage of this is higher on one side than on the other. In this arrangement is that the portion 11 can be actyp of d s it is ss t th t t l mp procurately formed in the molding operation, there- 15 Viding the light at the top of the beam on the by insuring the accurate location of the left right hand side of 'the road should have a fairly boundary of the beam and the ooncentration of sharp cutofi on its left edge with the maximum light near the left boundary. The portions of intensity as near the left edge as possible so that the lens :next to the risers 17 are subject to malwhen the passing beam is used the high intensity formation in the pressing operation. such mal- 20' will reach as far down the road as possible Wthformation may come from fillets formed at the out causing glare to an approaching driver on a corners of the glass or from sagging of the glass straight road. In that application there are Set in molding. I have used the term llet in the Orh SeVeTal pfincples Of design W c p oduce sense in which it is used in this art to mean the the desired lateral cutofi. This invention has to rounded corners obtained both at the top and 25. do with a further improvement in des having bottom of the risers 17 between flutes. The fillets 0 the same object. The result is achieved by emhave been shown on the drawing somewhat exploying flutes having faces of S-shape with a aggerated in size. Whatever be the design of portion O the face between the edges nearest fiutes the efiect of the fillets is to scatter light parallel with the opposite side of the lens so that v r a, wide angle so that such light does not the rays forming the left edge of the beam pass form a part of a useful beam. The amount of 5 through said portion while the rest of the light is light scattered by the fillets is so little that the d ec ed V y degrees o the t. This intensity is not seriousiy objectionable from the s iS desl'able because in p duct on it is posglare standpoint. The radius of the fillets varies sible to form the central portion of the fiute more substantially in production, depending upon the 35. cu t t t d p ons. Th dge temperature of the mold, glass, etc. As the rapo t s are deformed by fillets o the s s s dius becomes larger the fillet intercepts the useful sin Of the %lass in mOldng, etc., and q tportion of the flute farther toward the center. y the light passing through them iS c y d The maintenance of the direction of the last rected. ray from the useful fiute area therefore depends In Figur@ 1 I haVB shown a front View Of a lens upon the maintenance of the correct radius of e ody t nVentOnthe fillet. This limitation is avoided with my Figure 2 is a section on line 2-2 of Figure 1. improved form of flute as shown in Figures 2 F eu 3 is a similar section on an l r d and 3, since the light from the portions of the Sca e S w a eW O the mproVed fiutes and the iiute nearest the risers is thrown fal' to the right to direction Of Tays passing through them. and no attempt is made to secure an accurate 190 Figur@ 4 ShOWS the application 0f y proved boundary at this side of the beam. Where, howflute to a CO V 16118. ever, a conventional fiute is used the radius of In Figure 1 I have shown a lens such as is used the fillet determines the portion of the lens on automobile headlamps provided with wide through which the rays will pass that form the 50 fiutes 10 over the central portion., and narrower left boundary of the beam. Variation in radius fiutes 12 over the top and bottom portons. The of the fillets cannot be avoided in production so specific arrangeinent of flutes forms no part of that it becomes difficult, if not impossible, to acthe present invention. curately locate the left boundary of the beam In Figures 2 and 3 I have shown in detail the with the old style flute. 5, design of the flutes 10. It will be noted that each Another diiculty in directing the maximum intensity as far to the left as possible arises from the fact that certain portions of the flute sag when the glass cools in the mold. This sag changes the direction of light through portfons of the flute afiected. It is desirable that this sagging efiect be concentrated in portions of the flute which direct light Well to the right. In the case of the conventional flute experience has shown that the sag occurs in the portion of the flute which provides light near the left boundary of the bean. With the new flute the difficulty from sagging is largely avoided because the tendency to sag is restricted to portions of the flute next to the risers.

I have shown in Figure 4 that these fiutes may be employed with concavo-convex lenses such as are now commonly used on automobiles. Here a portion 22 of the flute is substantially parallel with the opposite face of the lens, while the edge portions diverge increasingly therefrom.

I claim:

1. A molded glass lens provided over the portion thereof which is adapted to transmit light rays to define a side edge portion of the beam with a plurality of substantially vertical flutes each having a face in the shape of an S-curve with an intermediate portion of the face nearest to parallel with the opposed face of the lens so that the rays passing therethrough are defiected the 'least and define said side edge portion, the portions of the flute on either side of the said intermediate portion directing light to the same side of the said edge portion whereby a sharp cut-off is obtained at the same edge.

2. In the lens as defined in claim 1 said flute faces being connected by risers extending substantially in the direction of the projected rays.

ROBERT N. FALGE.

Images