US2148315A

US2148315A - Electric lamp

Info

Publication number: US2148315A
Application number: US198670A
Authority: US
Inventors: Daniel K Wright
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1938-03-29
Filing date: 1938-03-29
Publication date: 1939-02-21
Anticipated expiration: 1956-02-21

Description

Feb. 21, 1939. D, KY WRIGHT 2,148,315

ELECTRIC LAMP Filed March 29, 1938 6 Sheets-Sheet 1 4Z l Inventor"- 'Daniel K. Wright,

Attorney.

D. K. WRIGHT Feb. 2l, 1939.

ELECTRIC LAMP 6 Sheens-Sheet 2 Filed March 29, 1938 inventor: Daniel KVVr'i ht,

Feb. 21, 1939. D K- WRlGHT 2,148,315

ELEGTRI C LAMP Filed March 29, 1.958 6 Sheets-Sheet 3 Inventor z Daniel K. Wright b5 y@ 5M His Attorneg.

Feb. 21, 1939. D. K. WRIGHT EEEEEEEEEE MP Ivento Daniel K. Wm

His Attorney.

Feb. 21, 1939. D, K, wRlGHT y 2,148,315

Filed March 29, 1938 6 Sheets-Sheet 5 Inventorz Daniel K. wright,

His Att car-neg.

Feb. 2l, 1939. D. K. WRIGHT 2,148,315

` l ELECTRIC LAMP V Filed March 29, 1958 sheetsL-sheet e Inventor-z Daniel K. Wrfght,

His Attorneg. Y

Patented Feb. 2l, 1939 UNITED STATES yParri-:NT OFFICE:N

ELECTRIC LAMP Daniel K. Wright, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New York Application March 29, 1938, Serial N0. 198,670

8 Claims.

My invention relates to an electric light projecting device comprising a bulb or envelope at least a portion of which is reflective of light. More particularly, my invention relates to a device of the type disclosed and claimed in my copending applications Serial No. 68,713, filed March 13, 1936, and Serial No. 143,504, filed May 19, 1937, of which the present application is a continuation-in-part. The said device comprises a bulb which is composedof at least two sections of vitreous material united together at their edges byfusion, at least one of said sections being of pressed material and forming a wall which constitutes a comparatively large proportion of the bulb wall. In the preferred form of my invention, both sections are pressed or preformed and united at their edges by fusion. This allows ready access to the inner surfaces of said sections so that they may be properly shaped or coated, and at the same time the union by fusion insures a hermetic seal which will resist gas pressure or a `vacuum.

My invention may be embodied in light projecting devices in which the light source is fixed at a definite point, such as the focal point of a reflector or other device for projecting the light. More particularly my invention. may be embodied in light projecting devices of the type in which a portion of the enclosure for the light source has a concave light-concentrating surface, preferably paraboloidal, at the focus of which is l0- cated the filament or other light source. One of the advantages of such light projectors is that they may be made in small sizes for use as headlamps on vehicles such as automobiles and airplanes where the small sized projector may be effectively incorporated in the stream-lined design of the vehicle. Another advantage is the possibility of extremely accurate location of the light source with respect to the reflecting surface whereby a beamof the correct dimensions and directions may always be secured.

Light projectors have heretofore been proposed in which a bulb was blown with a portion thereof shaped like `a paraboloid, this portionbeing subsequently silvered on the interior or exterior.

, However, the silvering of the exterior surface is objectionable because of the reection of the light by the glass of the bulb. On the other hand it is diflicult or impractical in such a case to silver the interior of the paraboloidal portion while maintaining the remainder of the bulb free from silver. Another disadvantage'of such a construction lies in the locating ofthe lament with respect to the reflecting surface since the seal between the stem on which the filament is mounted and the bulb must be kept plastic while the filament in being located because of inaccessibility to the filament and its supporting wires. If, on the other hand, an attempt is made to silver the paraboloidal portion Aof the bulb after the filament is mounted, there is a likelihood of depositing some of the silvering material on the fllament or of forming a bridge of the material across the leading-in wires and thus short-circuiting the filament. Furthermore, itis very difcult to prevent deposition of the silvering material on the remainder of the bulb in a practical manner.

One of the objects of my invention is to provide a construction for light projectors of the type described in which the above-mentioned disadvantages will be obviated. Another object is to provide a construction which is commercially practicable. One of the features of my invention is the provision of a glass reflector portion, preferably pressed glass, and a separate cover glass or lens portion sealed thereto; The concave glass or parabolic portion may be made with extreme accuracy by pressing, particularly when made of a glass having a low coefficient of expansion, such as that commercially known as Pyrex. Byv making the bulb or enclosure of separate sections, the refiector section may be conveniently coated internally with a reflecting material before the filament or other light source is mounted therein. The said light source may then be located at the focus of the reecting portion by optical means as, for example, by placing the unit in a hydrogen or other non-oxidizing atmosphere, energizing the light source, and observing the beam produced thereby on a screen.

While the above-referred-to copending applications disclose the general construction and arrangement of my light projecting device, the present application includes in addition thereto certain specific features of the same, particularly ,the construction of the sealing surfaces of the reflector and cover glass sections, and the construction of various interengaging means on the said sections for correctly positioning and locking the same in predetermined relationship with respect to each other prior to the sealing together thereof.

Where lamps of the type disclosed in the said ,copending applications Serial Nos. 68,-'713 and 143,504 are filled with a gas at a pressure above that of the atmosphere, it is necessary that the fused seal between the reector and cover glass sections be sumciently strong to resist any tendency of the internal gas pressure to disrupt the iti same and so separate or pryapart the two sections. To effect such a strong seal 4it is necessary that the abuttingsealing surfaces be completely fused along their entire contact width. However, considerable difficulty has been experienced in producing such a complete seal without impairment of the reflecting coating on the reflector section by the heat attending the sealing operation, and while maintaining the desired optical relationship between the two sections to be sealed together.

Another object-of my invention, therefore, is to provide an electric light projection device having an envelope composed of a plurality of optical sections of glass permanently and securely united in definite optical relationship with respect to one another. f

Another object of my invention is the pro-,

vision of suitable sealing surfaces on the glass sections comprising the bulb or envelope of my light projection devices, which surfaces may be readily fused together to provide a complete and strong seal capable of withstanding gas pressures within the envelope greater than that of the atmosphere. l

Still another object of my invention is the provision of suitable sealing surfaces on the glass sections comprising the envelope of my projection device which surfaces may be readily fused together to provide a complete and strong seal without impairing the reflector coating on the reflector section and without cracking the glass at and adjacent the seal.

A further object of my invention is to provide positioning means on the reflector and cover glass sections of the projection device for correctly positioning and locking said sections in accurate predetermined optical relationship with respect to each other preparatory to the sealing of the same and for maintaining such predetermined relationship during the sealing together of said sections.

A feature of the invention is the provision of registering surfaces on the lamp sections which are accurately located with respect to the optical surfaces of the envelope sections and are positioned remote from the sealing edges of the sections so that they are unaffected by the softening and distortion thereof during the sealing operations which therefore may be carried to the point where a strong uniform seal will result.

Further objects and advantages of my invention will be apparent from the following detailed description of species thereof and from the accompanying drawings, in which:

Fig. 1 is a horizontal sectional View of a light projection device comprising my invention; Fig. 2 is a front elevation of the projection device shown in Fig. l; Fig. 3 is an enlarged fragmentary sectional view of the reflector and cover glass sections taken on the 'line 3-3 of Fig. 2; Fig, 4 is a similar sectional view taken on the line 4-4 of Fig. 2; Fig. 5 is a fragmentary front view of the lower periphery of the reflector section adjacent the vertical center line thereof; Fig. 6 is a fragmentary sectional view of the reflector section taken on the line 6-6 of Fig. 2; Fig. 'l is a fragmentary front elevation of a modification of my invention; Figs. 8, 9 and 10 are enlarged fragmentary sectional views taken on the lines 8-8, 9-9 and IO-ID respectively of Fig. 7; Figs. 11, 12 and 13 are views similar to Figs. 8, 9 and 10 respectively of another modification of my invention; Fig. 14 is a view similar to Fig. 5 of the modified form of reflector section shown in Figs.

reflecting surface.

11, 12 and 13;`Figs. 15, 16 and 17 are views similar to Fig. 9 of three further modifications of my invention; Figs. 18 and 19 are views correspond` ing to Figs. 9 and 10 respectively of still another modification of my invention;l Fig. 20 is an enlarged fragmentary sectional view of the modiyfication shown in Figs. 18 and 19 taken on the line 20-20 of Fig. 19; and Figs. 2l and 22, Figs. 23 and 24, Figs. 25 and 26, Figs. 27 and 28, Figs. 29 and 30, and Figs. 3l and 32 are views corresponding to Figs. 9 and 10 respectively of still further modifications of my invention.

Referring to the drawings, particularly Figs. 1 and 2, the light projection device according to my invention comprises a bulb or envelope III consisting of a preformed reflector section or member II made of pressed glass and a cover glass section or member I2, also made of pressed glass. As is evident from the drawings, the cup or bowl-shaped reflector section II is of substantially uniform thickness throughout. The two pressed glass sections Il, l2 are sealedV together at their peripheries to form the bulb or envelope I0. 'I'he cover glass section may be plain, or it may be a lens having flutes and prisms on the inner surface thereof as shown in Fig. 1, or it may be provided with an inner light diffusing surface such as is produced by facets formed vthereon or by frosting the same. It is possible to use such a lens because of the fact that it is made as a separate part from the remainder of the enclosure, whereas with blown glass enclosures or bulbs of the type heretofore produced a suitable lens could not be formed. The reflector and cover glass sections II and I2 respectively are preferably made of low-expansion glass, such as that commercially known as Pyrex and described and claimed in United States Patent No. 1,304,623, Sullivan et al., issued May 2'7, 1919.

Greater accuracy is obtained with a low expansion.

glass due to the fact that there is very little contraction of the glass upon cooling. The interior surface I3 of the reflector section II may be of paraboloidal or any other suitable shape and is covered with a metallic coating I4 constituting a By pressing the reflector section rather than blowing the same, the interior surface I3 can be made with extreme accuracy, much more so than is possible with the conventional stamped metal reflectors or with blown glass reflectors, since the plastic glass conforms precisely to the curvature of the accurately formed surface of the plunger of the pressing apparatus. The metallic coating I4 is preferably, of aluminum, although any other suitable material` may be employed. The said coating I4 ls preferably applied to the interior surface IF by vaporization of the coating metal in a vacuum, as described and claimed in the United States patent application of R. F. Strickland, Serial No. 104,241, filed October 6, 1936.

The reflector section I I is formed With a pair of openings I5, I5 adjacent the apex thereof, and a central opening I6 at the said apex through which the bulb or envelope I0 is adapted to be exhausted. For conveying current to the device, I have shown a pair of terminal members I1, I1

of the type described and claimed in my United Enlarged outer portions I9, I9 of said prongs form

shoulders

20, 20 preferably tapered, with the reduced inner end portions I8, I8. Comparatively thin metal cups or thimbles 2|, 2I are united, preferably by brazing, to the tapered shoulders 20, 2II of said prongs, and have their edges or rims sealed and embedded ln the

bosses

22, 22 provided at the outer edges of the openings I5, I5. I prefer to seal the metal cups or thimbles 2l, 2I to the

glass bosses

22, 22 according to the method disclosed and claimed in the copending United States patent application Serial No. 85,516, filed June 16, 1936, by A. Greiner, E. Westerlund and the applicant herein. The metal cups 2l, 2| should ,be made of a metal to which the fused or softened glass will readily wet and stick, and should preferably have the same expansion as the glass, as near as may be. For low-expansion heat-resistant glass of the character hereinbefore indicated, I prefer to make the metal cups 2|, 2I of an alloy of iron, nickel and cobalt commercially known as Fernico and disclosed and claimed in United States Patent No. 1,942,260, issued January 2, 1934, to H. Scott. I have found that this particular alloy effectively fulfills the abovementioned requirements or conditions. A filament 23 is mounted on

leads

24, 24, which are in turn secured to the inner ends I8, I8 of the terminal members I1, I1. The filament is accurately located at the focus of the paraboloidal reflecting surface by being held in such position in a suitable jig during the attachment of

leads

24, 24 to the prong ends I8, I8. The filament 23 is also located in a definite position angularly with respect to the terminal members I1, I1, the said filament and terminal members being preferably positioned in substantially the same plane. After exhaustion of the bulb or enclosure IU through the opening I6, the same may be filled with an inert gas such as argon, nitrogen, or a mixture thereof. If desired, this gas filling may be under a pressure such as, for example, two atmospheres.

As mentioned above, the cover glass and reector sections of the light projection device are made separately, being pressed from 10W- expansion glass, and are then sealed together at their peripheries by means of a pin-point flame from a burner to form the bulb or envelope Ill of the device. To form a strong, permanent and hermetically effective seal between the two bulb sections capable of withstanding considerable internal gas pressures, without impairing the reflecting coating I4 which has been previously applied to the interior surface I3 of the reflector section II, I have found it highly desirable to construct the sealing surfaces of the reflector and cover glass sections in the particular manner illustrated in the accompanying drawings.

Referring particularly to Figs. 3 and 4, the reflector section II is formed at its periphery with a rim 25 having a sealing surface 26 the plane of which is accurately located perpendicularly to the axis of the paraboloidal reflecting surface I4. The cover glass section I2 is likewise formed at its periphery with a sealing surface 21 on a rim 28, the plane of which surface is also accurately located perpendicularly to the axis of said cover glass section. As is evident from the drawings, the sealing surfaces 26 and 21 are spaced outwardly an appreciable distance from the periphery of the interior paraboloidal surface I3 of the reflector section so that the heat necessary to completely fuse the sealing surfaces together along their entire contact area or zone will not affect or alter the said paraboloidal inner surface I3, or vaporize or otherwise impair the refiecting coating I4 on said surface. Furthermore, the sealing surfaces 26 and 21 are made of relatively small width or radial extent, such as, for instance, one-eighth inch or thereabouts, so that the heat necessary to completely fuse said surfaces together can be localized and the seal thus formed completely in a very short time, before sufficient heat is conducted by the adjacent glass to the inner paraboloidal surface I3 of the reflector section II to adversely affect the same or the reflecting coating I4 thereon. To prevent cracking of the glass, among other things, at and adjacent the seal, the abutting sealing surfaces 26 and 21 are made Substantially flat and uninterrupted throughout their entire extent, as shown in the drawings. By completely fusing the abutting sealing surfaces from their outei` peripheries clear through to their inner peripheries, a feature made possible by the particular construction of the sealing surfaces described above, the existence of sharp crevices leading to the inner edge of the fused joint is entirely avoided, thereby eliminating the possibility of the internal gas pressure separating or prying apart the two sections II and I2 comprising the bulb or envelope Il), a result which would normally occur, if such crevices were actually present, from the wedging action exerted on the walls of 'such crevices by the internal gas pressure.

To further insure against the possibility of separation of the two sections II and I2 by the internal gas pressure, both the reflector and the cover glass sections Il and I2 are provided with

annular grooves

29 and 30, respectively, immediately adjacent the inner peripheries of the sealing surfaces 26 and 21 on said sections. The

grooves

29 and 30 are substantially semi-circular in cross section and are adapted to lie opposite one another when the cover glass and reflector sections are sealed together in correct optical relationship with respect to each other so that the outer edges of said grooves are exactly aligned, as shown in Figs. 3 and 4. The result is that the surfaces 3i, 32 of the reflector and cover glass sections immediately contiguous to the inner periphery of the sealing surfaces 2d and 21 approach the latter at approximately right angles. When proper care is used in the sealing operation, the said inner surfaces 3|, 32 of the two envelope sections form a continuous and uninterrupted wall extending substantially perpendicularly to the plane of the sealing surfaces. The envelope surfaces immediately adjacent the inner edge of the fused joint therefore have practically no convergence at the point of fusion. This is of particular importance where the envelope is to be filled with a gas under pressure since it eliminates all tendency for localization of tensile stresses in the seal which might cause its failure. y

While the reflector and cover glass sections II and I2 can be pressed so as to have remarkably true optical surfaces, it has been found quite difficult to maintain accurate alignment of these surfaces while their sealing edges 26, 21 are softened and joined together. This is particularly true when the sections are relatively thick and the heat required to completely fuse the sealing surfaces 26, 21 together is considerable. In the present construction, definite optical alignment of the reflector and cover glass sections II and I2 is maintained at all times by the provision thereon of a reference zone comprising positioning and interlocking means which are independent of the sealing surfaces 26, 21 and 'are relatively unaffected by the heating and softening of the

yrims

26 and 28 of said sections during the sea/ling operation. The said registering and positioning means comprises a recessed annularreference surface or seat 33 on the cover glass disposed in a plane normal to the axis thereof. The s'aid recessed seat 33 is spaced slightly inward from theannular groove 30 so as to form an annular lip or ridge 34 between said groove and seat. The inner surface 35 of the ridge 34 is -made substantially straight and is tapered at a denite angle, preferably 30, with respect to the axis of the cover glass. Inwardly of and immediately adjacent the groove 29 therein, the reflector section is formed with an upstanding annular embossment 36 adapted to lie opposite the annular reference seat 33 on the cover glass section when the two sections are properly aligned with vone another. The embossment 36 preferably extends outwardly beyond the pane of the sealing surface 26 on the reflector section so as to project into the recess formed by the recessed reference seat 33 on the cover glass section and overlap the annular ridge 32 thereon. As shown in Fig. 3, however, the embossment 36 is spaced a slight distance from the annular ridge 34 on the cover glass section and from the annular reference seat 33 so as to provide a passageway 31 therebetween communicating with the annular chamber formed by the

grooves

29, 30 in the reflector and cover glass sections. The annular embossment 36 is formed with a plurality of projections 38 extending upwardly from the upper and outer surfaces of said lembossment and spaced uniformly around the'circumference thereof, said projections being adapted to abut against and snugly fit the recessed reference seat 33 and the tapered inner surface 35 of the ridge 34 to thereby accurately align the two envelope sections.

In order to properly engage the reference seat v 33 and the tapered surface 35 respectively, the upper surfaces 39 of the projections 38 are so formed as to lie in-a common plane normal to the axis of the paraboloidal reflector section Il while the outersurfaces 40 of said projections are tapered at the same angle as that of the said tapered surface 35. The projections 38., together with the reference seat 33 and tapered surface 35,I Vthus provide means for positioning and maintaining the reflector and cover glass sections in correct optical relationship with respect to each other transversely or radially of the reflector axis.

To position and maintain the reflector and cover glass sections in correct rotative or angular relationship with respect to each other, I have provided additional interlocking positioning means comprising a small conical recess 4I (Fig. 4) in the sealing surface 26 on the reflector section, and a corresponding conical locking lug 42 projecting from the sealing surface 21 on the cover section. The conical recess 4I is adapted to snugly receive the locking lug 42 to thereby lock the two envelope sections in accurate angular relation preparatory to the sealing together of the same. Thus, where the cover glass section I2 is in the form of a lens having prisms and flutes thereon, as shown in Figs. l and 2, the lug 42 may be so located on such lens with respect to the said flutes and prisms as to properly position the same with respect to the reflector section II and the filament 23 mounted therein. To correctly mount the projection device in its supporting holder,

the outer surface of the reflector section Il may v be provided with a positioning lug 43 (Figs. 1 and 4) adjacent the periphery of said section and preferably in angular alignment with the conical recess 4I in the sealing surface 26.

In assembly of the lamp or projection device, the reflector section I I, which has been previously provided with the filament 23, terminal members I1 and reflecting coating I4, is placed in a sealing chuck and a cover glass section placed thereon with the conical lug 42 engaging in the conical recess 4I and the various projections 38 each engaging the reference seat 33 and tapered surface 35. When so positioned, the sealing'

surfaces

26, 21 are preferably slightly separated from each other, but after proper heating the said surfaces soften and are fused together, the cover glass being supported throughout this process on the projections 38. Thus the predetermined relation of the cover glass to the reector section is maintained undisturbed despite the heating and fusing together of the rims of the two sections.

During the sealing operation the depending lip or ridge 34 on the cover glass, together with the upstanding embossment 36 on the reflector section, act as baffles across the line or plane of the seal and prevent such hot gases as are forced into the envelope by the sealing flames from impinging directly on the reflecting coating I4 or the various flutes and prisms on the cover glass. Since the embossment 36 is spaced from ridge 34 to provide the passageways 31 communicating with the chamber formed by the

grooves

29 and 30, any chance of undesired gases being trapped in said chamber during exhaustion of the envelope is completely eliminated.

Referring now to the modification shown in Figs. '1 to 10 inclusive, the projection device there shown differs from the previous form in that the reference seat and the reference projections are reversed, the reference seat being located on the reflector section Il while the reference projections are located on the cover section I2. Thus as shown in Figs. 8, 9, and 10, the reflector section II is formedwith an annular reference surface 44 extending around the margin of the parabolic surface I3 in a plane normal to the axis thereof. This surface 44 is bounded by an annular ridge 45 of glass the inner edge 46 of which is equidistant from the axis of the parabolic surface I3. The cover glass section I2 is formed with a depending annular embossment 41 so located thereon as to lie directly opposite the reference surface 44 on the reflector section when the two sections are correctly aligned. A number of uniformly spaced projections or buttons 48 extend from the said embossment 41. While most of these projections are shaped as to flt snugly Within ridge 45 and bear against reference surface 44, one projection is enlarged into a circular boss 49 which bears against surface 44 and registers with a semi-circular notch 50 formed in the ridge 45. As in the previous form of the invention, the embossment 41 acts as a baille across the line of the seal during the sealing operation, preventing anyhot gases that may be forced into the envelope by the sealing flames from impinging directly on the reecting coating I4 or on the cover glass prisms and thereby impairing the same. Inasmuch as the embossment 41 is spaced from surface 44 by the thickness of the buttons or projections 48, any chance of undesired gases being trapped in the annular chamber between the embossment and the sealing rims is completely eliminated.

The modication illustrated in Figs. 11 to 14 inclusive is very vmuch the same as the form of the invention shown in Figs. 1 to 6, the angular positioning means however being slightly different. Thus in the modification the angular positioning means consists of a circular boss 5|, similar to the boss 49 Vin Fig. 1, which is adapted t0 fit snugly in a semi-circular notch 52 in the ridge 53 on the cover glass. The upper surface 39' of said boss 5| is adapted to engage the reference seat 33 in the same manner as the upper surfaces 39 of the projections 38'. The semi-circular grooves 54 and 55 in the reflector and cover glass sections respectively are made slightly smaller than the

grooves

29, 30 shown in Figs. 3 and 4.

The modification shown in Fig. 15 differs from the construction shown in Figs. 11 to 14 merely in the shape of the annular grooves 56 and 51 in the reflector and cover glass sections respectively, the said grooves being relatively shallow and of extended width.

In Fig. 16 the groove 58 in the reflector section II is continued inwardly to the inner surface I3 thereof to thereby provide, in effect, an annular ledge or recess from which a plurality of reference buttons or projections 59 extend. 'The cover glass I2 is formed with an annular groove 60 adapted to lie opposite groove 58 and is also formed with a. depending embossmcnt 6I having an annular ridge 62 and reference surface 63. The said ridge 62 and surface 83 provide a seat, similar to that provided by the ridge 34 and surface 33 in Figs. 3 and 4, for the various projections 59 on the reflector section. The ridge 62, since it extends across the line of the seal, further acts asra baffle during the sealing operation, the same as ridge34 in Figs. 3 and 4 and embossment 41 in Figs. 8 to 10. The angular positioning means between the reflector and cover glass sections in the modification shown in Fig. 16 may either be of the form illustrated in Figs. 1 to 6 or of the form illustrated in Figs. 11 to 14.

In the modification shown in Fig. 17 the annular groove 64 in the reflector section il provides a reference surface 65 for cooperation with a plurality of uniformly spaced projections B6 on the depending embossment 61 of the cover glass section I2. The groove 64 is bounded at its inner extremity by an annular ridge 68, the outer surface 69 of which is tapered so as to provide a seat for the tapered inner surface 10 of the projections 66. As in the previous forms of the invention, the cover glass I2 is provided with an annular groove 1I adapted to lie opposite the groove in the reflector section II. The angular positioning means (not shown) in this modification may be of either of the forms previously described in connection with Figs. 1 to 10.

Referring to the modification shown in Figs. 18 to 20, the groove 12 in the cover glass I2 is continued inwardly to the inner wall 13 thereof to form an annular ledge providing a reference surface 14 against which an annular upstanding ernbossment 15 on the reflector section I I is adapted to bear. The said embossment forms the inner boundary of the groove 16 in the reflector section, and is recessed at uniformly spaced points around its circumference, preferably 90 apart, to thereby provide notches 11 having tapered

side walls

18, 18 and a lower wall 19 coinciding with the bottom of the groove 16. The cover glass I2 is formed with a corresponding number of depending projections or lugs adapted to extend into the notches 11 and so lock the reflector and over glass sections II and I2 respectively in correct relationship with one another. The side walls 8|, 8| of the projections 80 are tapered so /as to seat on the tapered

walls

18, 18 of the notches 11. Also, the height of the projections 80 is made less than the depth of the notches 11 so that the bottom wal182 of said projections is slightly spaced from the bottom wall 19 of the notches, thereby providing a passageway communicating with the annular chamber formed by the oppositely disposed

grooves

12 and 16 through which passageway any gases trapped in said chamber may be withdrawn.

In the modification shown in Figs. 2,1 and 22, the reflector section I I is formed immediately adjacent the inner edge of the sealing surface 26 with an annular groove 83 of relatively small semi-circular section. Inwardly of said groove the reflector section is provided with an upstanding embossment 84 the upper surface 85 of which constitutes a reference surface. The cover glass I2, inwardly of the sealing surface 21 thereon, is recessed to form a ledge 86 from which a plurality of uniformly spaced projections 81 depend, said projections being adapted to engage the reference surface to thereby properly align the reflector and cover glass sections II and I2 respectively. To further assist in aligning the said sections the side wall 88 formed by the recess or ledge 86 is tapered to provide a seat for a plurality of similarly tapered projections 89 extending from the outer surface 90 of the embossment 84'. As shown in Fig. 22, the angular positioning means in this modification comprises a lug 9|, preferably a semi-circular boss, extending from the tapered side wall 88 and adapted to snugly fit into a correspondingly shaped recess 92 in the outer surface of the embossment 84. To permit evacuation of the annular chamber formed bythe groove 83, the outer surface 90 of the embossment 84 is spaced a slight distance from the tapered side wall 88 to thereby provide a passageway communicating with said chamber.

Referring to the modication illustrated in Figs. 23 and 24, both the reflector and cover glass sections II and I2 are formed with annular grooves 93 and 94 respectively substantially semicircular in cross-section and adapted to lie opposite one another when the said sections are properly aligned. The outer surface 95, however, of the groove 93 is made ilat and is tapered outwardly to form a reference seat `for an annular ridge 96 formed on the'cover glass immediately adjacent the sealing surface 21 thereon. The outer wall 91 of the ridge 96 is tapered to correspond to and seat against the tapered outer surface of the groove 93. Thus, the engaging surfaces 95, 91 form continuations of the sealing surfaces 26, 21 on the reflector and cover glass sections II and I2 respectively and assist in properly aligning said sections. "Inwardly of the groove 93 therein, the reflector section II is provided with an upstanding embossment 98 the upper surface 99 of which forms a reference surface against which a plurality of depending projections |00 on the cover glass are adapted to bear. As shown in Fig. 24, one of these projections is extended to provide a locking lug IOI which is adapted to project into a corresponding recess |02 in the embossment 98 to thereby constitute angular positioning means for the reilector and cover glass sections.

The modification shown in Figs. 25 and 26 is substantially the same as the construction disclosed in Figs. 21 and 22 except for the crosssectional shape of the grooves |03 and |04 in the reflector and cover glass sections respectively. Thus in Figs. 25 and 26, the groove |03 in the reflector section is made relatively shallow and is of extended width, while the groove |04 in the cover glass section is formed with an outwardly tapering outer wall |05.

In the modification disclosed in Figs. 2'7 and 28, the cover glass I2, inwardly of the sealing surface 21 thereon, is recessed to form an annular ledge |06 from which a plurality of uniformly spaced reference projections |01 depend, said projections being adapted to bear against a reference surface |08 constituting the upper `surface of an upstanding embossment |09 formed on the reflector section To further aid in aligning the reflector and cover glass sections the side wall ||0 formed by the recess or ledge |06 is tapered so as to uniformly seat on the tapered outer wall of the upstanding embossment |09. The engaging surfaces ||0 and thus form continuations of the sealing surfaces 26, 21 on the reflector and cover glass sections respectively as well as providing means for properly aligning the said sections transversely of each other. As shown in Fig. 28, one of the projections on the cover glass is extended to provide a locking lug ||2 which is adapted to snugly t into a suitably shaped recess ||3 in the embossment |00 to thereby form angular positioning means for the reflector and cover glass sections.

In Figs. 29 and 30, the sealing surfaces of the reflector and cover sections are slightly curved instead of being straight or flat as in the previous forms of the invention. Referring to Figs. 29 and 30, the front surface of the reflector section rim 25 is recessed at its inner periphery to form an annular ledge ||4 providing a reference surface against which a plurality of projections H5 on a depending embossment ||0 on the cover section are adapted to bear. The upper surface of the annular ridge ||1 formed at the outer periphery of the rim 25 by the recessing thereof, is curved about a center located approximately on the edge ||8 of the said rim to thereby provide an arcuate sealing surface H9. The cover glass I2 is formed with an annular depending embossment |20 inwardly of the edge |2| thereof, the outer surface |22 of which embossment is curved to correspond with the curvature of the sealing surface 9 on the reflector section Intermediate the annular embossments ||6 and |20 on the cover glass section, the latter is.formed with an annular groove |23. As in the previous modifications illustrated in Figs, 23 to 28, one of the projections on the cover section |2 is extended to provide a locking lug |24 (Fig. 30) which is adapted to snugly iit into a recess |25 in the ledge ||4 to therebs7 provide angular positioning means for the reflector and cover sections.

In the modification shown in Figs. 31 and 32, the sealing surfaces on the reflector and cover sections extend throughout their entire width at an angle to the plane normal to the reflector axis instead of parallel thereto, as in most of the previous modifications. Other than this change the construction is very much the same as that shown in Figs. 29 and 30. Referring to Figs. 31 and 32, the inner surface |26 of the annular ridge ||1 on the reflector section rim 25 is inclined at an angle of approximately 60 or thereabouts to the plane of the reference surface ||4 and forms the sealing surface on said section. The edge |21 of the rim 2B on the cover section is correspondingly inclined to uniformly seat on the sealing surface |26 and thus form the sealing surface on the cover section |2. As a consequence of the inclination of the sealing surfaces |26, |21, the said surfaces constitute supplementary aligning means, in addition to the projections ||5 and reference surface ||4, for properly aligning the reector and cover glass sections.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric projection lamp comprising a light source, an enclosure comprising a glass reflector portion and a glass cover portion assembled and in contact with each other at their rims, said contacting rims comprising a sealing zone in which the rims are united by fusion and a registering zone in which the said rims seat together but are not united.

2. An electric projection lamp comprising a light source, an enclosure comprising a glass reiiector portion and a glass cover portion assembled and in contact with each other at their rims, said contacting rims comprising a sealing zone in which the rims are united by fusion and a registering zone in which the said rims seat together but are not united, said sealing zone being spaced from said registering zone.

3. An electric lamp enclosure comprising a glass reflector section and a cover glass section each having optical surfaces designed to coact to produce a definite light distribution, registering means on said sections determining their optical relationship in assembled position, said registering means comprising a reference surface on said cover glass section and a plurality of reference projections on said reflector section positioned in registry with said reference surface, and sealing means forming a gas-tight joint between said sections, said registering means being wholly independent of said sealing means.

4. An electric lamp enclosure comprising a glass reflector section and a cover glass section each having optical surfaces designed to coact to produce a definite light distribution, registering means 0n said section determining their optical relationship in assembled position, said registering means comprising a reference surface on said reflector section and a plurality of reference projections on said cover glass section positioned in registry with said reference surface, and sealing means forming a gas-tight joint between said sections, said registering means being wholly independent of said sealing means.

5. An electric lamp enclosure comprising a glass reflector section and a cover glass section provided with cooperating annular rim portions, each of said sections having optical surfaces designed to coact to produce a definite light distribution, said rim portions being formed at their outer peripheries with oppositely disposed annular sealing surfaces and at their inner peripheries with registering means determining the optical relationship of said sections in assembled position and having opposed annular grooves intermediate the said sealing surfaces and regis" tering means.

6. A glass enclosure for a light projection device comprising a reflector section having a reflecting surface, a reference surface adjacent its periphery and disposed in a plane normal to the axis of said reflecting surface, and a sealing surface at its periphery and spaced from said reference surface, and a cover section for said reflector section, said coversection having an annular reference embossment adjacent its periphery and engaging said reference surface to thereby position said sections in correct predetermined relationship with one another, and a sealing surface on said cover section at the periphery thereof and disposed in corresponding relation to the sealing surface on said refiector section, said sealing surface being spaced from Vsaid reference embossment.

7. A glass enclosure for a light projection device comprising a reflector section and a cover section, said cover'section having a reference surface adjacent its periphery and a sealing surface at its periphery, said sealing surface being spaced from said reference surface, sai-d reflector section having van annular reference embossment adjacent its periphery and engaging said reference surface to thereby position said sections in correct predetermined relationship with one another, and a sealing surface on said reflector section at the periphery thereof and disposed in corresponding relation to the sealing surface on said cover section, said sealing surface being spaced from said reference embossment.

8. A glass enclosure for alight projecting device comprising a reectorv section provided with a reflecting coating on its inner surface, said reflector section having a sealing rim at its periphery provided with a substantially fiat sealing surface, a cover section for said reflector section having a sealing rim at its periphery provided with a similarly fiat sealing surface disposed in corresponding relation to the sealing surface on said reflector section, and an annular embossment on one of said sections disposed between said reflecting coating and said cooperating sealing surfaces and intersecting the plane of said sealing surfaces to thereby form a baule serving to protect the said reflecting coating from the sealing ames.

DANIEL K. WRIGHT.

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