US1590740A - Paneled reflector - Google Patents

Description

June 29 1926. 1,590,740

(3. E. GODLEY PANELED REFLECTOR Original Filed y a. 1922 4 Sheets-Sheet 1 June 29 1926.

C. E. GODLEY PANELED REFLECTOR Original Filed May 8. 1922 4 Sheets-Sheet 2 June 29', 1926.

c. E. GODLEY PANELEb REFLECTOR Original Filed May 8, 1922 4 Sheets-Sheet 3 June 29 1926. 1,590,740 6;. E. GODLEY PANELED REFLECTOR Original Filed y 8. 1922 4 Sheets-Sheet 4 Patented June 29, 1926.,

cairn s rata-1s rarest cnnnnns n. e-onnnr, on nnrnornr/ironrsan, nssre'enon rofnnmnnnsaa'ogivns conronn'rron, or nnrnorr, Mrcnrennn conroaa'r on on NEW YORK.

"PANELED nn'r'nnoron.

Original application fi1er1"May 8,1-19'22', serial'No. 559,204. Divided and this application file-d May 3,

' 924. Serial No. 710,769.

This invention relates to the construction of the reflectors of projecting lamps,'especially the headlamps of motor vehicles, and its object is to so dividethe reflector 5 into sections that therays of the light Will be projected upon a clearly defined limited area, and in part concentrated upona re stricted portion of sucharea. V

Lamp builders have long sought to pro- 1o vide headlights for vehicles \Vl1lCl1':WOUlCl give an even illumination of the roadway from immediatelyin front of 'the vehicle to a point in advance thereof sufliciently dis- 'tant to permit the driver-to see and avoid all obstructions, and furthermore, to attain this object with the least expenditure of electric current.

Lamps equipped with the well known parabolic reflectors cannot produce this cf- 2 fect as the'illumination of the roadway at a given distance from the vehicle is either veryrestricted or is much fainter than the roadway nearer the vehicle. lVlien such lamps are so positioned that the concentrated light properly illuminatesthe roadway sufliciently far in'advance to .permit'the driver to avoid obstructions, "the roadway nearer the vehicle is left dark. Or ifthe light bulb is so positioned that the proj ected rays illuminate the roadway near the vehicle, too much 'li ht is projected upward and sidewise .Where it is liable to blind drivers of other vehicles and pedestrians. My present invention aims to overcome these objections While still employing a simple reflector of a substantially parabolic type, by deforming thereflector so that different portions thereof will project beams whose cross-sections are similar in. shape but different in size, so that the larger beam will afford a general road illumination of considerable spread While the more concentrated beam will-aflord a driving beam which will light a narrower :st'retchof'road for considerable distance ahead of the vehicle.

Furthermore, my invention consists "in will not interfere With-the usual machine polishing of the reflecting surface. More over, it consistsin providinga reflector con struction which Will be equally suitable for considerable variations both in thespread Ofethe-beamaand in their relative intensity, and also adapted to be 'usedfor substantially allptirposesWhereit is desirable to project beams of relatively different transverse diameters.

In accomplishing these purposes, lemploy-a reflector of a generally paraboloidal form-and subdivide this reflector into a plurality .of .panels which extend transversely of the directions in which the-beam is to be expanded, each of these-panels havingits longitudinal m-edial portion disposed forwardly of the general paraboloidal form of the reflector farther thanits 'lateral edges. I vary the depth ofl the" convexity of the cross-section or the Widthof the panels according to the desired spread of the projected beam, and vary the relation of the central lines of the panels 'toithe vertical plane passing through the axis of the reflectoraccording to the directions in which the, beam is to beexpanded.

The cross-section of each panel on a line radialto the inner: edge of said panel is the same as a horizontal cross-section of the same Width of a determining parabola, the center of this cross-section of the determining .parabola being in a-line passing through the focal center of both bodies and through substantially the middle of said cross-section of said panel, but reversed. Thisrule holds with reflectors having -pa11- els, all of -Wl1OS sidesare parallel and vertical and avith reflectorsdivided into panels of irregular form so long as the cr0sssec-' tions of these panelsare tilted into the planes in Which'the light is to be spread. For example, ifthe central lines of the panels in a headlight-reflector having a fhori-' zontal axis wereall in vertical -planes, the beams of the reflector Would be expanded from circular to elliptical cross-sections with the: maj or a xisz of *the "ellipses horizontal. I-f-the endshfsrich gene1-'ally upright panels curve slightly toward eorFaWay from a. vertical :spl-ane, the beam rvill "be changed in cross-section fsnbstaiitially to that of a horizontal .-Ifctangle.

. gsnoh alterations llll obe'ain iseoti'onfs can be accomplished by means of panels of varying transverse sections, I prefer to convex each panel forwardly in the, relative transverse sections of a parabola of slightly longerfocusthan the norinal parabolic retlector for the greater distribution, and transverse sections of a parabola of amuch longer focus for the more concentrated light. By using the longer-focus transverse sections, the panels can all be of the same width or any predetermined width, the spread of light being determined by the focal length of the parabola used in determining the transverse. sections of, the panels.

By using transverse parabolic sections in the panels I find that the light raysrefl'ected frorneach panel diverge equally from the axis of the reflector, the rays from each panel covering substantially the anticipated field of, light, of the difl erentsections.

l have also found that if the convexityof each panel is just the reverse of the normal parabolic section for the .sameportion of the reflector, using narrower panels for greater concentration and wider panels for the more difiusedlight, that the width of panels are determined by the width of spread desired in the projected fields.

This application isa division of my copending application, Ser. No. 559,264, filed May 8, 1922, which has been restricted to reflectors in which all the panels extend in the general direction of one plane and-which may also have their ends bowed relative to said plane if'desiredr 1 Q In the accompanying drawings, Figure 1 isfafront elevation of a reflector embodying the present invention. Figure 2 is a section on the line of Figurel. Figures 1 2, 1 and 2 are diagrams showingthe method for determining the proper crosssections of the paraboloidal panels. I Figure 3 a front elevation of a slight modified type of reflector and Figure is a section in the line l'4t thereof.

. Similar reference characters refer to like parts throng iout the several views.

-The reflector 1 is generally parabolic in form. If a light bulb could be nade with a filament with substantially no dimensions and thisfilarnent mounted at the focus of the reflector, then this reflector, it a perfect parabola, would project a b-eainof light of the diameter oft-he reflector. T .e filaments of light bulbs are, however. of considerable size so that the light projected is in the form of a cone whose surfaceis somewhat indefinite.

After the parabolahas been formed and polished, itis placed between proper dies andits surface is deformed so as to be'divided into panels 8 and 4-, those next to cen-- tral aperture 2 of: the reflector in Figures 1 and2 being narrower than those farther awa-yr-"Eachof these panels has substair tially straight sides, that is, the contacting sin-es of two adjacent panels are in a plane parallel to the focal .axis'of the reflector, and theplan-es between the panels converge toward each other from one side'o't' the reflectorthrough theretlector t the other side thereof, the surface of each panel be ing distorted from the original paraboloida-l surface or the surface of revolution .of a parabola. -.-The result is that added diffused light is projected toward the corners of the main projected field so that instead of a circular field of. light, this reflectorprojects afield which is substantially rectangular.

The .desiredwvidth of the panels being liXGd, the exact cross sectionsof the panels my be determined after the manner shown in Figs. 1 to 2 inclusive. For any given portion of the panel E shown in Fig; 2 I first determine the center G of the crosssectionof the corresponding part of the original or true paraboloidal surface 1, as shownin Fig. 1*. I then'draw a line from this point G to the focus F of the trueparabolic surface portion and also plot the correspondingportion of a determining parabola P. 'The focal length of the reflector 1 indicated by the line B and that of the parabola P by the line C. The'point H at which the focal line F G intersects the determining parabolaP indicates the central point of'asmall section of the parabola P which has the proper curvature for the desired panel cross-section. If this-determining parabola is of greater focal length that the parabola 1 (which is part of the true paraboloidal surface from which the reflect-or is to be formed and which it will still approach rather closely when finished) this curvature is reversed as shown in Figs. 1 and 1". v

Cross-sections of the panel 3 atother points are similarly determined, each being taken radiallyto the inner edge of the panel asshown by he lines K in Fig. 2 This insures a panelwhich effects an-unusually uniform distribution of light. Owing to the resulting uniform density of the projected beam and of the beam-widening effect :due

to the edgewise curving of the panels' they cooperate in projecting a. beam of approximately rectangular cross-section with its upper and lower borders substantially parallel to the plane of the line E in Fig. 2." The lines K indicate how the rays of light are deflected up and down so as to proceed along lines substantially at right angles to the border lines of the panels at the points of reflection.

Where the panels are at any other angle to the vertical plane of the reflector or parallel thereto, the same process for determiningthe curvature of the panelscompos ing the reflector may be followed, as indi-. catedin Figs. lhand 2". This is true no matter at what .angle the line E, 2 crosses theside edges of the panels.

Each of the panels presents a transversely convex surface toward the plane of the open end of the reflector and the curvature of such panel at every point in its lengtl'i is desirably the same as a horizontal crosssection of the determining reflector talren in a line passing through the focal points of both reflectors, reversed and placed so as to coincide withthe normal paraboloidal reflector surface at the edges of each panel and tilted into th'e planes in which the light is to be spread. The curvature of each panel is therefore greatest at the horizontal diameter of the reflector.

This parabolic transversecurvature of the several panels enablesine to determine the exact field to be illinninatedQby the rays 'reflected by each panel, and the rays of the light from each panel are projected so as to fall evenly upon the entire predetermined field of illumination, that is, illuminate evenly the field on both sides of the axis of the reflector. The angle of diffusion there fore of the rays reflected by any particular panel depends upon the focal length of the determining parabola and upon the width of the panel. Vi here the focal length of the determining parabola is short and the curvature of the panel is greater, the beams from that panel will be diffused over a greater area than where the focal length is greater, but the diffusion is accurately controlled, which is impossible with panels which are circular or elliptical in crosssection.

Referring again to Figures 1 and 2, it will be noticed that each of the panels is of substantially even width throughout its length. The projected field will therefore be approximately rectangular, that is, the upper and lower ed 'es will be nearly horizontal. The central portion of this field will be more intensely illuminated than the outer portion and this area. of intense illumination may be swung up or down as desired by tilting that portion of the reflector which embodies the central panels relative to the two outer groups of panels. That portion of the reflector which is formed into panels whose width is greater in proportion to their depth approaches more nearly a true parabola, and the light projected thereby is therefore more concentrated, that is, pro jected onto a more restricted field, and I prefer that these panels shall be tilted upward about one degree so that this smaller and more intense field of illumination will be positioned at the upper portion of the less intense but larger field.

Where an automobile headlight is less than four feet from the roadway and the rays therefrom strike the roadway about two hundred feet from the vehicle, the width of the area of intense illumination should be that of the roadivay and it may extend about one hundred feet toward the 7 ands: is formed with panels 7 and 8 which taper upwardly. The transverse curvature of these panels are again determined as above described and the focal axis of the central panels is tilted downward relative to the axis of the outer groups so that an in tense field of light will be imposed on a milder field and on the upper portion there of. The field of light projected by this reflector against a wall at substantially right angles to the axis of the groups "of panels will have its corners well filled out.

he field of light projected by this reflector will again be approximately rectangular with a brighter central portion and with the corners well filled out. The brighter central portion can be moved up or down by tilting the focal axis of the central portion of the reflector relative to that of the two outer portions and the relative intensities of these two portions of the field Will depend on the areas of the panels in the several greups.

i clann:-

1.. A concave reflector symmetrical with respect to a vertical plane passing through the axis of the reflector and including a number of panels whose bounding edges are in a surface of revolution of a conic section, the medial lines of the panels being in planes which are parallel to the axis of the reflector but incline toward said vertical plane on one side of said axis, each panel departing from said surface of revolution to produce a reflecting surface which will deflect rays of light relative to a horizontal plane.

5.. A concave reflector symmetrical with respect to a vertical plane passed through the axis of the reflector, and including anumber of tapering surfaces, the bounding edges of said surfaces being in planes parallel to the axis of the reflector which converge from the widest portion of each surface, each surface departing from a'general surface of revolution to produce a reflecting surface which will deflect rays of light an amount approximately equal to the angle between the inner of the bounding planes and said vertical plane.

3. A concave reflector symmetrical with respect to a vertical plane passed through the axis of the reflector, and including a number of tapering surfaces, the bounding edges of said surfaces being in planes parallel to the of the reflector which con.-

' general focus of the reflector.

l. A concave reflector symmetrical with respect to a vertical plane passed through the axis of the reflector, and including a number of tapering surfaces the bounding edges of said surfaces being in planes parallel to the axis of the reflector which converge, each surface departing from a surface of revolution to produce a reflecting surface which will deflect rays of light an amountapproniniately equal to the angle between the inner of the bounding planes and said. vertical plane, said wedge vshaped surfaces all being convex.to ward the general focus of the reflector, the transverse curvatureof each portion of each such surface being the same as that of the general cur e of a parabola at that point but in the opposite direction.

5. A concave reflectorasymmetrical with respect to a vertical plane passing through the axis of the reflector and including a number of panels, one of the bounding edges of'each of the panels being in a plane which is inclined to said vertical plane, each panel being convex toward the open end of the reflector to diffuse light along horizontal lines and to deflect the raysof light relative to the vertical plane of the reflector, the-

Images