[1]United St,,ites Patent Office 298379052 2,837,052 INDICATING APPARATUS 6 Andre P' Viret, Ridgewood, N. J., assi@-nor to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Application January 17, 1956, Serial No. 559,603 11) 1 Clain-i. (C]. 116-129) Th:s,in vention relates to indicating apparatus and p-ir- 15 tici,ilarl v to indirectly illuminated indicatin.- devices and i?iteg.- al lighting arrangements for instruments wherein it is desired to illuminate indirectly both the indicia which -is o@i a light-conducting dial and one or more indicato@- el@ments or pointers which are asso-@iated with the dial. 20 '!'lie invention is especially applicable to indicating instrumen ts suitable for use both @in daylight and also in a darke.,i -.d environment requiring so-called "night vision." Heretof ore, the conventional approach to the I>roblem ,of providing satisfactory indirect illumination for indicat- 25 iriapparatus has involved the motintin.a of one or more lamps or li,&ht reflectors in corners provided in an instrument bezel @in alignmeiit with the edge of the transparent dial plate so that indirect illumination of the indicia is produc ed by iight rays which enter the edge of the dial 30 plv,te in radial directioiis and are internally transmitted and reflected throiigh the transparent dial material so as to impinge upon the indicia, other light rays passing di- ' rectly from the lamp across in front of the dial face so as to illuminate the pointer; Such a ccnstruction is dis- 35 cIGs@- -d for example in the copending ai)plication by myself and W. R. Polye, Ser. No. 351,856, filed April 29, 1953, now U. S. Patent No. 2,768,606 -ranted October 30, 1956, and assigned to the same assignee as the present applicat ion. 40 It has previously been propc>sed to @-ncompass the dial face and the zo-.le of operation of the pointer by a prisii-iatic light-conducting rin.- which lies in a parallel plane irt front of the dial face so that light rays introduced into the rin.- from in front of the dial pass from the ring ra- 45 dially inward across the dial face to illuminate the pointer, or to illuminate both the pointer and the dial face if ithe dial is opaque. Such construc-tions are disclosed and claimed for example in U. -S. Patents 2,140,972 and 2,259,91 0 to G. V. Rylsky, granted December 20, 1938 50 and October 21, 1941, respectively, and assigned to the same assi- ee as the present application. 'n Howev er, the mounting of lamps in a bezel in alignment with the edge of the dial has been found to be unaccepta ble in certain applications such as aircraft panel 55 installati ons, since such lamp location increases the outside dimensions of bezel and casing. In one prior unit employi ng a prismatic edge portion or rim integral with the light-conducting dial plate and extending in front of the dial face, it was proposed to locate the lamp b,-hind 60 s,ich edge portion so that illumination of the indicia and pointer was accomplished solely by those light rays froin the lamp whicli entered the back of the ed.-e portion, certain of these entering rays bein.- reflected from the rim sur-'Lace of the edge portion radially into the main 6r) body portion of th.- -dial plate for internal transmission to illuminate the indicia, the balance of the entering rays being reflected f@rom the rim sur-face radially inward across the dial face to illuminate the pointer, the rear <)f the dial bein.- completely shielded by an opaque back- 70 in.- member so that no light would be permitted to enter the re4r of the dial. In such prior arrangements, much PtL-@,-ented June 3, 1953 of the light emitted from the lamps @ither is absorbeq by the backing member or escapes in directiois iway froni the dial and is abs,@@-bed -,i;ld wash,-d iii the nism behind the dial, which places a distinct liniitation upon the quantity of light rays available for ilILiminatiiic, the indicia and pointer with the intensity and uniformit; required. Moreover, the fact Cnat some of the li.-ht rays entering the prismatic edge portion are thereafter diverted for illuminating the indicia results in a ftirtlier redL'.Ction in the quantity of light rays available for illuminating the pointer with the adequate intensity and uniformity required. In my ec)pending application Ser. No. 559,607, filed simtiltaneously with the present application, there is disclosed noivel indicating apparatlis wherein ther@-, is provided a dial structure of light-transmittin.- material includin- a main body portion having -@tn opaque front dial surface which may be circular and which may be provided with li,&ht-transmitting indicia, and one or m<)re po-inters are disposed in front of the dial surface for cooperation with the indicia. The dial structtire also includes a marginal li.@htin.- portion @vhich may be annular and whicli extends ahe,,td of the dial surface and is constructed so as to project a first group of received light rays out of thi@, marginal portion across in front of the dial surface, to illun-iinate the pointer, and there is provided means ineltiding one or more light sources located rearwardly of the main body portion with unobstructed straight-line paths therebetween for passing the first group of light rays into the marginal portion to illuminate the pointer and for passing a second grolip of li.-ht rays into the rear end surface of the main body portion for internal transmission therethrough to impinge upon and illuminate the indicia. In the specific constructions described in mycopendin.- application the rear end slirface of the marginal lighting portion is arran.-ed to receive the first -roup of li.-ht rays. For this purpose the rear end surface is made substantially coplanar with the rear end surface of the main body pordon, and the lamps are st@.pported oii the side wall or rear end wall of the outer housing for the apparatus. Clearance space must be provided between such housing and the casing of the pointer actuating mechanism so that the lamps may project a second group of light rays through such space into the rear end surface (yf the marginal portion. Due to such clearance space necessarily required between the apparatus outer housing and the @casing.for the actuating mechanism, the resulting outside @dimensions for the apparattis outer housing are larger than can be accommo.dated in some installations, and moreover, such clearance makes more difficult the problem Of SUPPOTting the actuating mechanism centrally without intercepting the rays which must rear-h the rear of the marginal Eghting portion and the rear of the main body portion. The constructions disclosed in the present application make it possible to eliminate clearance space between the outer housin@g for the apparatus and Lthe casing for the actuating mechanism, and light waste is minimized. The subject matter of the present application is in the natlire of an improvement over the specific constructions illustrated in my aforesaid copending application. It is an object of the present invention to provide iinproved indicating apparatus. It is another object of the invention to improve the illumination of indicating devices and particularly to improve indirect illumination or integral li.-hting for indicating apparatus. It is another object of the invention to provide novel means for producing indirect illumination or transillumination ofrelatively high intensity or brightness for the indicia and indicator elements of indicating apparatus. It is a ftirther object of the inventioli to provide novel
[2]3 means for producin- substantially Liniform indirect iHumination or transillumination for the indicia and indicator cle.ments of indicating apparatus. lt is a further obj--ct of the, invention to provide a novel self-contained indicatin.- instrument haviiig a relatively small outside diameter wherein the source or sources of illumination is located rearwardly o,L the din,] surface for indirectly illumi-@iatin- tl).- dial indicia and indicator elements located in front of the dial face. It is a still further object of the invention to provide a novel indicating instrumerit of re@'atively small outside diameter which does not incorporate an instrument bezel and may be clamped or otherwise directly mounted on an instrument panel in a compact arrangement along with a series of other similarly mounted instruments. It is a further object of the invention to provi@le improved indicating apparatus wherein the dial indicia is illumiiaated from the rear of the dial and the pointer or other indicator member is indirectly illumina',ed b3, means of an auxiliary mar.-inal lighting portion, the arrangement being such that little light is wasted and no clearance between the outer housing for the apparatus and the casing for the actuating mechanism is required as a prerequisite for illuminating the indicia and indica'@or member. The fore.ooing and other objec@ts, features and advantages of the present invention will become aD Lrent herep inafter from a consideration of the detailed description which follows taken together with the accompanying drawing v,,herein one embodiment of the invention is illustrated by way of examp'@e. In accord@nce with one aspect of the invention th@,-re is provided ind-trectly illuminated indicating apparatus comprising a dial structure composed of radiant energytransmitting material, for exar@iple light-transmittin.@ material, and having a main body port,@On with a front dial face which is for the most part impervious, for examp'@e opaque, to the radiant ener@y rays and which is apertured with indicia capable of passing or transmitti-,ig the rays of radiant energy, at least one indicator member or poiiiter disposed in front of the dial face for cooperation viith the indicia, means for producing relative movement or relative rotation between the indicator member and the indicia, the dial structure having a marginal or peripheral lightin.- portion which may be annular and is provided with a prismatic extension which extends for,,@,ardly abead or in front of the dial face and which is constructed, for example by selected beveling, so as to project a first group of received rays of radiant ener@y out of the marginal portion across in front of the dial face to strike the visible portions of the indicator member to illuminate the same, and means including at least one radiant energy source located rearwardly of or behind the main body portion and its dial face, with unobstructed straight-line paths between the source and the rear of the main body portion, ior or cai-ising the first group of rays to pass into the mar.-inal portion of the dial structure for illuminating the indicator member and for directina or causing a secl-nd -roup of riys of radiant ener.-Y to ;ass into the re?,r of @the main body portion for internal transmission throu-h the mf,.in body portion so that such ra3rs progress in a transverse generally axial direction and impin.-e upon or escape oLt through the indicia into the e3,es of the observer, thereby illuminating the indicia. In accordance with the present inv.-ntion the radiant energy source or sources is positioned behind the main body portion and is spaced closer to the central longitudinal axis of the apparatus than is the marginal liabtin- portion, and the marginal lightin,- portion is provided with a prismatic extension whicii extends rearwardly of or behind the main body portion so as to pick up or receive the first grotip of radiant energy rays which pass outwardly in generally radial directions, away fro@-n the central axis and which is constructed, for exaiiiple by 2,837,052 4 selected beveling, so as to direct the received first grotip of rays internally through the marginal lightin.- portion into the forward extension of the marginal lighting portion for projecting across in front of the dial surface to illuminate the indicator member or pointer. The light source or sources may be carried by the frODt end of the casin@ for the actuatinmechanism, and if the rearward extension has a beveled surface the source m-,iy lie substanti,,Ily in a plane which i-. norinal to the ct@ntrzil 10 axis and which passes througl-i the center of the bevelcd sarface. Whe!- cdesignconsiderationsrequircillumination of the indicator member with m--ximtim inteisity for example, the aforesaid dial structure may comprise an assembly of two or more members. Tlius, the dial struc15 ture may include an indicia-bearing m-iin dial meniber or dial plate of lighttransrnitting or li,@ht-coiiduct;iig material and a separate mar.-inal li.-hting member or lighting ring of similar material which has a forward extension - xtending ahead of the main dial mcitiber for 20 projectin.@ the first group of rays onto the indicator member and which has a rear extension extending rearNvardly of the main dial member for picking up the first group of rays. Where other design considerations prevail, the marginal or peripheral portion and the main .5 body portion may instead be integral p-,rts of a unitary dial structtire rather than separate members. In the drawin- wherein like reference charactcrs refer to like elements throughout the various views, Fi.-. I is partial sectional viei4, alon.- the line 1-1 of 30 Fig. 2 of one form. of indirectly illuminated in dicatin.instrument in accordance with the pr@-sent invention; Fig. 2 is a front plan view of the instrument of Fig. 1; Fig. 3 is an isometric view of the rjial structure of Figs. 1 and 2; 35 Fi,-. 4 is an isometric view of the aLIXiliary marginal lightin.- ring of Fi_Qs. I and 2. Turning to Fi.-s. 1 and 2, there is provided an indica,or unit having a cylindrical metal housin- 2 which is threaded at its rear end 4 to receive a threaded metal cover plate 40 6. Solder may be provided at 4 if an hermetic seal is desired. Fitted within the side wall of the housing 2 is the casing 8 of the actuating mechanism for the print,-r or pointers. The actuating mechanism may be a conventional follow-up synchro device or conventional meter 1,5 movement. Secured to the front end of casin.- 9 by screws 10 is a circular platform 12 of electrical insulation material. Threaded into platform 12 are t,@N,o or more rigid posts 14 for supportin,- the dial structure indicated generahy at 20. 30 As illustrated, the dial structure includes a marginal lighting portion in the form of a lightin.- ring 22 positioned radially by having its outer annular surface 15 fitted within the inner side wall of housing 2, and a main body portion in the form of a circular dial plate 24 hav35 ing its outer annular surface fitted within the inner annular wall of ring 22 at 21. Ring 22 has an annular lip portion 23 which extends radially inward a slight amount beyond dial plate 24 to hold the dial plate and its attached assembly against axial movement in a forward 6o direction. The dial plate may be secured to the posts 14 by means such as screws 16. The dial plate and mechanism assembly may be held or locked against rearward axial movement by suitable means. For example, spring means such as a compression spring 17 may be 65 positioned between the cover plate 6 and the rear end of casing 8. Electrical connections 18 are passed herrnetically through cover plate 6 for ener.-izing the lamps and the actuatin.- device inside casin.- 8. 7o F-ing 22 and dial plate 24 may be composed of li ghttransmitting or lightconducting plastic material such as methyl methaerylate. For example, "Rexolite," "Lucite" or "Plexiglas" are suitable for this purpose. All surfaces of ring 22 are highly polished. The flat front surface 25 of dial plate 24 rnay be covered by a layer of translu75 cent white paint which in turn is covered by a layer 26
[3]c),g@7,052, oi opaque paint or black printer's ink. The indicial comprisin.- the graduations 28, the numerals 30 and the legend "Fuel Flow," are cut ;.3ut of the opaque layer 26 with the white' paint exposed underneath so that the indicia are light-transmitting. Altemativ@ly, the indicia may be cut or engraved in the front surface 25 of the dial plate and the resulting recesses may be filled with translucent white paint, the remaining flat surface being covered with a layer of opaque paint or printer's ink which may be applied by a roller so as to leave the whitepainted indicia areas uncovered. The actuating device in casing 8 rotates a shaft 9 which e,-,tends alon.- the central longituainal axis A-A of the indicator unit. Shaft 9 extends through a central aperture 13 provided in platform 12 and through a cen- I r) tral aperture 32 provided in dial plate 24. SecLired to the forward end of shaft 9 is a pointer 44 which may be composed of metal or of the same transparent plastic material as riii.- 22 and the dial plate 24. More than one pointer may be employed if desired. The pointer 20 surfaces m-,ty be completely coated ,vith a layer of white paint, and portions such as the tail end which are to be non-visible may be covered over with a layer of aii opaque paint. The visible portions may have a triangular transverse cross-section with sloping or beveled sur- 25 faces 45. Mounted on platform 12 are one or more lamp and socket assemblies. For the indicator unit illustrated in Figs. 1-4, three lamp and socket assemblies may be em, ployed. Two of the three lamps are shown in Fig. I for 30 the sake of simplicity. Each lamp socket comprises a pair of diametrically opposed metal sprin.- clips 33 secured to platform 12 and serving as one electrical contact for en- 'age@nent with the side body contact of the lamp. The second socket contact for enga,@ement with the cen- 35 tral contact pin of the lamp is provided by a right-angle metal spring 35 secured to platform 12. If desired, an aperture 37 may be provided in spring 35 and a rivet type socket contact may be supported in an - insulation washer mounted in the aperture so that the rivet is in- 40 sulated from the spring 35. For the sake of simplicity, the electrical connections to the socket contacts have been omitted at the sockets. The filament and envelope 39 of each lamp extend beyond the socket clips 33 for 45 the lamp so as to project rays of light tow-,trd the dial structure in a manner which is about to be - described. The filaments of the lamps may be equally spaced from each other and from the axis A-A. For example, the lamps may be arran.-ed so that the central longitudinal axis of each lamp is tangential to an ima.-inary circle 50 which is symmetrical about axis A-A. As shown in Fig. 1, the lip portion 23 is part of a rimlike peripheral extension of the lighting ring 22 which projects ahead of the indicia-bearing dial surface and is 55 provided with an annular 45' 4bevel surface 46. The bevel begiis apbroximately at the plane which includes the opaque layer 26 or the dial face so that the bevel will not direct any light rays radially inward to escape and pass across at 21 into the body of dial plate 24 be- 60 hind the dial face. In accordance with a feature of the invention the lightin- ring 22 is provided with a second peripheyal extension.@ This extension projects - rearwardly of the dial plate 24 and is provided with an annular 45' bevel surface 47. In the embodiment illustrated th e plane which includes the lamp filaments passes through c "5 the center of the annular bevel surface 47, thereby resulting in internal reflection from bevel 47 of a maximum nuniber of the li.-ht rays which enter the annular inner surface portion 49 of the rearward extension. 70 In accordance with a feature the straight-line paths between the lamps and the annular rear surface portion 24' of the dial plate behind the indicia are left unobstructed and the lamp ftlaments are spaced from the central axis A-A, for example approximately the same 75 I () 6 radial distance as are the indicia, in positions such that some of the light rays 29 from each lamp enter the rear dial surf@ce 24' approximately directly behind the indicia and are transmitted internaily to progress in a transverse generally axially direction through the dial plate 24 so as to escape from the dial plate out through the lighttransmitting indicia, thereby illuminating the indicia. At the same time the lamp filaments are positione-d with respect to the rearward extension of ring 22 so that the remaining light rays from the lamps which are directed to,@vard the dial assembly 20 are those rays 31 which are directed outwardly in general-ly radial directions and enter the lighting rin.@ 22 by entering its annular surface portion 49 in the particular construction shown. The light rays 31 are internally reflected from the annular bevel s-,irface 49 and in turn are transmitted internally through, the ring until they strike the annular 45' bevel surface 46 from which they are internally reflected so as to be projected out of the annular exit surface 23 on the lip portion of ring 22 in generauy radial directions inwardly across in front of the dial face and approximately parallel to the dial face tintil they strike the white-painted sloping surface 45 of the pointer 44 for reflection in a diffused manner into the eyes of the observer. A flat metal ring 48 is sandwiched between the lightin.ring 22 and the transparent cover glass 50 to serve as a sp-@cer aiid also as a stray light shield to intercept rays of light which emerge in an oblique forward direction fromtheexitsvrface23towardthecoverglass5O. Cover 50 may instead be composed of transparent plastic material if des-red. Except for shield 48, such oblique rays wo.-ild ol,lierwise pass into the eyes of the obser-ver as one type of glare. Where required, the inner rim portion of 1-in- 48 may be bent at an oblique angle toward the dial surrace. If desired ', a second flat shield ring having approximately the same inside diameter as rin.- 48 may be positioned on the opaque layer 26 around the otiter circumference of layer 26 so as to intercept those rays of light which emer.-e from the exit surface 23 in an obliqtic rearward direction toward the indicia and the baclcgrouild dial surface areas adjacent to the indicia, thereby casting a shadow across the indicia and indicia back,-round to eliminate the type of glare which would otherwise result if such light rays were permitted to reflect from the indicia and indicia background into the eyes of the obseiver. SLich a shield arrangement is disclosed in my aforesaid copcnding application Ser. No. 351,856, now U. S. Pateiit No. 2,768,606. In order to provide an hermetic seal for the instrument a motal ring 52 is soldered to the housing 2 and is provided wi' h a ilange portion 54 which may be cemented or soldered to the cover .-lass 50. A series of aniiular grooves 56 are cut in rin,@ 52 so that ring 52 is gripped ti@-h'tly for stipport within the associated aperture in the instrumeit paiicl (not shown). In the dial strticture illustrated, the bevelled surfaces 46 and 47 for illumiiiating the pointer is formed on a lightip.- rin.- 22 which is a niember separate from the dial m--r.- iber 24. Such construction is relatively simple to manufacture and assemble in the completed indicator unit. Also, sitice the engaging surfaces of ri@i.- 22 and dial pla'Lc 24 are not absolutely smooth, the physical contact -,.t 21 is not perfect or complete. Since there is no app,,eciable optical contact between ring 22 and dial plate 24, a negligible number of the light rays 31 in ring 21are perniitted to escape iilto the side of the dial plate, which would otherwise diminish the number of light rays available for projecting across the dial face to illtiminate the pointer with the intensity and uniformity required. I-lowever, where other considerations prevail, the lightin@ ring 22 with its bevel 46 may be integral with the dial plate 24, the resulting unitary dial structure having the same general outline as elements 22 and 24 shown in Fi.-. 1.
[4]7 Although a specific embodiment Gf the invention has been illustrated and described in detail by way of exan-ipl-, it is to be exdressly understood that the invention is not limited th-@reto. Various modifications are possible. For examol@-, the lainp filaments may be spaced at a shorter rtdial distaiiee from the central axis A-A than is the raciial distance of the indicia from axis A-A, which increases the spacing b--tween the lamos and tlie liglitin- ring 22, thereby reducin.- the heatin@ effect of tile iamps upon ring 22. Also, whe.-e of the pcinter with reduced intensity is permitted, tl-ie .amps may L-,e located partially or compl--tely rearward of ring 22 as long as a predeterr,-iined n-@,mber of light rays are able to enter sui-face portion 49 to be reflecled irternally fror@-1 the bevel surface 47 aiid in turn frorii the bevel stirl'ace -@,6. Only a few arrows have been s'loivii to illtistrate @-eprese.-tative light rays. Mcreover, selected ar,-as on the rear surface 24' behind the indicia niay be r-3i-,ghened or pairted while or slipplemented by -,iux;,Iiary pieces c@i' I;aht-cot-id,,@icting plzis'@ic m@ aterial -Lo difluse the rnore intelise li,-ht roys neirer the lamps so as 'Lo provide a niore uniformillumination of the indici@i. Also if desired. a-.i auxiliary flat lightin- plate of light-conductin.plastic r-@-iaterial may be positioned adjacent to the rear surface 24' of dial plate 24 aiid the lamps positioned so as to d;recl the I-I.-lit rays throu_d-i such auxiliary lightin.plate in a ,cnerzilly radial directions, the areas of the rear 'late behi surface of sl@ch auxiliary light;ng p -@id the iiidicia being trea'Led or pai,.ited @vh-'@te so as to difi-tise or reflect the light rays corresponcling to rays 29 internally in generally axial forward directions iito the dial plate for internal transmission therethrough to illuminate the indicia while other light rays from the lamps correspondin.- to rays 3'@ p,-6s into the lightin@ ring to illumirate tl-ie pointer. Sucli auxiliary lighting plate ai-ran.@ements are disclosed for example in the cc@t)endin,- adplication of G. C. Sturges, Ser. '@1,To. 282,639, filed April 16, 1952, now U. S. Patent No. 2,768,605, granted October 30, 1956, and the copending Pppiicatio-@i of G. S. Hunter and G. C. Sturges, Ser. No. 572,158, filed March 16, 1956, as a continuation-inwho'c of later abandoned application Ser. No. 251,614, fil,-d O.-tober 16, 1951, the aforesaid patent and applicatio--s b-.ing assign-,d to the san-le assignee as the. present applicatign. For purposes of illuslration aiid simplifi-@atioa various shapes and i-elative dimetisions and locations of par'@s have been exaggerated. Various chan---es may be made in the desi.-i-i and arran-.eme-,it of parts without d.-parting from the spirit and sc(-,pe of the invention as deiined by the appended claim as will now be understood by tiiose skilled in the art. 2,837,052 8 I
