US1794586A - Focusing device for light signals - Google Patents

Description

March 3, 1931. TE 1,794,586

FOCUSING DEVICE FOR LIGHT SIGNALS Filed Aug, 25 1926 5 FIGS. 56.4.

nu u 1 Patented Mar. 3, 1931 \AINSLIE 'r. canrnn, or CO;LDWATER, ew Year, Assre'non To GENERAL RAILWAY j SIGNAL oomre'ntbr'noofins rnn, NEW YORK rooosrite nnvrcn ron LIGHT SIGNALS Application filed Au ust 25,1926; Serial No. 131,467.

lhis'invention relates to light signals for railwaysignaling purposes, and more par ticularly to a device'ior making it easy to determine When alamp has been properly adjusted to have its filament on focus.

In the typical light signal, an incandescent lamp With a concentrated filament is used in combinationiwith a lens, a mirror, or other suitable light projecting means to project a light beam'of limited spread to give aisignal indication, eitherjby virtue of ,its color or association with other-beams of light. 'In order to obtain the desired range and spread, it is essential that the'filament of the incan- 1 descent lamp be located accurately at the focal point otthe light projecting unit. In-

candescent lamps, as ordinarily manufactured, have some variation inthe location of the filament to a lamp base, so that when a nei vtlamp is put in alight-signahthe filament will. rarely come at-th'e exact focal point. To take care of. these variationsyit,

In accordanceavitlrthe present invention it isproposed to provide sighting orfinding devices which will-. indicate when t heifilament of the lamp has-been adjusted to. the

to make such finders of, a simple construction so that they may becheaply manufactured and" permanently, instal led1 as apart Y of each signal. Another object is to provide a finder which may be easily adj ustededuring the process of assembling the signal, so.

that the finders will define/the right-point for the location of the lamp filament for that particular .signal,independently of accuracy ofmachining the various parts; Alstillfurther obiject is to arrange the lines-of sight defined by the' findersiwith relation to the lines of movement of' the socket as'it is adjusted so as. to ,facilitatethe adjustment of the so c k otil f N right point.- jOne-obj'ect of the inventipn is Further objects and advantages of the invention Will be inpart apparent andin partpointed out as the "description pro s si the accompanying drawings, shows a vertical sectionthrough a light signal embodying the invention, said section being transversely of the aXisof the light projection unit and taken on the line l1 in Fig.2, r

, Fig 2 shows. another vertical section through the signalon-the axis ofthe lens;

a Fig. 3 shows a longitudinal sectionthrough oneflof, the *finclersy 1 :F. g. 4 is an endview of the finder; and

, Fig. 5 is 'a transverse section through the finder onth e line 55 in Fig. 3. c -W'hile the invention may be applied to light signals ofvarious types it has been shown in the drawings in connection with a single.light projecting unit. employing the Wellknoivn doublet lens combination. This unit shown .is capable of emitting only one 'beam of light of a: particular color, and in practice would be: combined With the other light units "giving other distinctivecolors; or severallike units Would be disposed in a predetermined relation, so as to give an in dication by the disposition or arrangement of.

' the "lights of the same ordiiierent colors.

The various details.- and. characteristics of the light signal itself are not material to the present invention;.and the particular form shown is merely representative.

; The signal nnit illustrated comprises a boxlike easing 1;,-hZLVl11g 1tS back closed by a swinging-door 2 which is provided wit-lithe usual gaskets,-. ventilator, hinges and fasteners The-casing 1 is formed with openings. 3 at the top and bottom. The bottom opening supporting bracket B, so. as to 'formaball andsocket connection, and the casing lis secured to this bracket:- by bolts 4. The

bracket (B in turn, is supported on a suitable pole 5, orthelike, ;being adjustable thereon Fig. l y

PATENT: orricr;

3 receives ag rounded' projecting lug on the and held in place by screws 6; The opening 3 atthe top, together, with thesimilar opening inthe bottol nrof the."next casing superimposed on theone shown,prov1des convenient pas:

sage for wires; but since only one casing is illustrated, this top opening is covered by a cover plate 7. To the front wall of the casing 1 is secured the usual hood 8.

The inner and outer lenses 9 and 10 of the usual and well known doublet lens combination, are held by gaskets and bezel rings in the usual way in a tapered lens barrel 11 which is secured in an opening in the front wall of the casing 1 by bolts 12. The inner bezel ring 13, retaining the inner lens in place, is formed of an inverted U-shape, as

' shown in Fig. 1, and adjustably supports the lamp and the sighting device or finders o-f and back on lines substantially parallel with the axis of the lens. Upturnedfianges'at the ends of the member 16 are fastened by bolts 18 to the lower ends of the inner bezel ring 18, said bezel ring being formed with vertical slots 19 (see Fig. 1) through which said bolts 18 pass, and the upturned flanges of the member 16-being formedwith horizontal slots 20 for said bolts. Thus, the shelf 16 may be moved up and down or sideways with relation to the axisof the lens. This way of supporting the socket 14 permits the lamp to be moved in and out, sideways in either direction, or up and down, with respect to the axis of the lens,.in anyone of three directions approximately at right angles. It should be understood that this adjustable support for the socket'is merely illustrative, and that various other adjustable supports permitting adjustment in these or similar directions may be employed in connection with the finders or sighting devices about to be described. p The incandescent lamp 15 is of any suitable construction, with a concentrated single or double filament located with respect to its basewith the usualmanufacturing inaccuracies. 7

The finders, designated as aswh'ole F, are fastened to the inner bezel ring'l3 to provide lines of sight substantially at right anglesto each other and parallel with the directions in which the socket may be adjusted up or down and sidewise. Referring particularly to- Figs. 3, 4 and 5, each finder comprisesa base 22, with holes for the screws 23 fasten ing the finder to the bezel ring. To this base 22 is fastened a tubular'extension 24, having ii shaped notch designated 25 cut in one side. This tubularextension24 may be secured to the base 22 in any suitable manner by soldering, sweating in, or spinning. The

outer end of the tubular extension 24 is formed with a longitudinal slot 26 (see Fig. 5), for the purpose hereinafter explained. The tubular extension 24 supports the tube 27 constituting the sighting device or finder proper.

The outer end of this sighting tube 27 is covered by a piece of ground glass 28 held in place by a ring 29, soldered or otherwise suitably secured'to the end of the tube. On this ground glass is placed suitable point designating marks, such as the cross hairs 30 (see Fig. 4), although spots, small rings, or the like may be employed. At an intermediate point in the length of the sighting tube is a partition 31 with a central small pin hole 32. To fasten this partition 31 in place, the tube 27 is prefer-ably slotted transversely about half-way down, and the partition inserted and sweated or soldered in place. This partition 31 is preferably made as thin as practicable, and the hole 32'relatively small so as to'form an efiicient light directing means. The inner end of the tube 27 is formed with a V-sliaped slot; and a plate 33, inclined at about degrees to the axis of the tube, is secured by solder or the like to the tube at one edge of this opening, as shown in Fig. 3. mirror 34. 'As shown, small retaining ears are pressed out of the plate 33 and bent down over the edge of the mirror 34 to hold it in place. I

, Since small inaccuracies in the location and size of holes, alignment of finished surfaces,

and the like, are unavoidable in practical manufacture, it is not expedient to attempt to make the finders F and assemble them on the bezel ring 13 with the expectation that they will accurately define a particular point with'reference to the bezel ring. Also, small variations inthe lenses themselves, and in their supporting elements, prevent the correct focal point for a given lens combination always being at a fixed space relation to the inner bezel ring 13. Consequently, in practicing this invention, it is proposed to assemble" the parts asth-ey happen to come,

put alight in the socket and light it, and then 1;;

adjustthe'socket, irrespective of the -finders F, until the filament of the lamp-is at the correct point to givea beam of the desired intensity and spread. This condition is obtained by direct observation of the beam of light itself; and while this may be done by viewing the signal from a distance, the adjustment .of the lamp socket to put the filament on focus is preferably made in a darkened room, inwhich there is a screen with marks thereon to define the proper size of the beam for the selected distance between thesignal and the screen. 7

Having determined in this way the proper point for the filament of that particular sig- To this plate 33 is secured a small nal, the problem is to have the finders Fdefine that particular point, so that-the filaments of other lamps may be adjusted to that same point and be focused for the most eilicient beam for that particular signal. Hth the filament lighted, its image is reflected by the mirror 34 of each finder F through the pin hole 82, which has the effect of a lens, and onto an'image receptive'surface in the Y form of ground glass 28. The image of the filament is sharply defined on the ground glass 28, and is larger or smaller than the actual image, depending upon the comparative distances between the pinhole 32, which acts as a light directing device somewhat similar to a lens, and the mirror 34, and ground glass 28. In short, for a given markon the ground glass, or ch find-eraccurately defines a sighting line. i

lVhile the finders may be made to define the point at which a properly focused filament is located by putting the cross hairs on the ground to mark the point Where the image actually comes after the assembly and the focusing operation just explained, the various inaccuracies might bring such marks on the ground glass off to one side, limiting the field of the finder; and rather than correct the inaccuracy in the construction and location of the finders by marking the cross hairs in the right place it is preferred to make the finder proper, including the mirror, pin hole, and ground glass, adjustable on its support. In the particular construction shown, the tube 27, when first assembled, may be moved in or out, or turned; and by these movements it is possible to bring the image on the cross hairs 30. The tube 27 is then permanently secured to its supporting base 22 bylrunning solder into the slot 26 in the tubular extension 24:. In this way, the finders may be readily adjusted in spite of inaccuracies in the menu facture and assembly of the parts, and after adjustment may be permanentlyfixed in position for the particular signal. This proc-edure of determining-the focal point of a signal by actual inspection, and adjusting and fastening thefinders in position to define the correct focal point can be easily perground glass 28 of-each finder, the socket is then adjusted in or out, up or down, or' sidewise, as the case maybe,'to bring thefilament of that particular new lamp at theright point prescribed by the finders.

The finders F afford two lines of sight intersecting at right angles in a common plane; and these lines of sight are made parallel with the directions in which. the socket and the lamp filament more-as thesocket isadjustcd upa'nddown orsideW-ise in said plane.

After the e zlrety-has-been moved in or out alo -1 the axis of the-lens to brin the lam 3 i filament in the, common-plane of the lines of sightof the finders, then the adjustments up erence tothe exact focalflpoint so asto obtain the greatest efficiency; from the filament;

The images of the filament stand out clearly onthe groundiglassesof the finders, evenin daylight, and in position where theycan be easily observed while adjusting the lamp,

so that the procedure of adjusting a1 lampis carried out-to much betteradvantage; than if theoperator had to peep through asighting opening; Various other practicaljad-v vantages of the filament sighting. arrangement. of this invention wlll lee: apparent Ito those-skilledinthe art. 5 a

' lVhile the invention has been described with reference to one specific construction and arrangement of parts,l;desire-to'haveit understood that this construction is susceptible, of various adaptationsandamodifica tions without departing fi'olntlie functions and principles characterizing the invention.

hat I claim is v1. Fomsin means for lamps for light signals comprising, in combination with a lens and a support'bemfing a fixed relation thereto, a lampsocket adjustably attached to said support for independent movement in three directions substantially at right angles to each other, one direction being along the axis of said lens, two like optical finders each comprising a telescopically related base and sighting tube, each sighting tube having a mirror directly exposed to light from alamp in said socket and an image receptive sur face with point identifying marks thereon,

and means permanently securing the bases of said finders to said support with the axes of their sighting tubes parallel with the axis of the lens and separated substantially 9O degrees in a planetransverse to said axis,

- 2. In alight signal, the combination with a lens and an adjustable lamp support, of an optical device for indicating when a lighted filamentof alamp in said socket lies in a sighting l1ne,-sa1d optlcal device comprising a tube disposed with itsaxis substantially parallel to the axisof the lens, a mirror at one end of the tube inclined substantially l5.

degrees to itsaxis, and directly exposedto light from a lamp in said socket, means at the other end of said tube constituting an image receptive surface" having point identifying' marks thereon, IIIBEIIISVHI the tube for projecting an image of a lighted filament refiected from the mirror onto said receptive surface, a base supporting said tube, and means fixing the base with respect to said optica'lfdevice. 1 o s 3. In a light signal, a lens, a retaining ring bearing against the inside edge of said lens, a lamp and socket therefor disposed With their axes transverse to the axis of the lens and adjustably supported by saidring to move in three directions substantially at right angles to each other, one of said directions being substantially parallel to the axis of the lens, two finders of the same construction fixed to said ring'substantially 90 degrees apart and defining sighting lines parallel with said two directions-in which said lamp socket may be moved transversely to the axis of said lens, each finder comprising a base fastened to thering and a tube received in said base for movement along and about the axis ofsaid tube, a mirror nearthe end of each tube inclined substantially 45 degrees to I i v its axis, a ground glass with point identifying' marks thereon at the other end of said tube, means in said tube for projecting the image of a lighted filament reflected from said mirror onto said ground glass, said tubes extending" substantially parallel with the axis of the lens and having their ground glasses both visible at'the same time from the rear of the signal.

Intestimony whereof I hereby aifix my signature. 5 v

AINSLIE T. CARTER.

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