US2490776A - Manufacture of sealed lighting unit - Google Patents

Description

Dec. 13, 1949 R. K. BRAUNsDoRr-F MANUFACTURE OF SEALED LIGHTING UNIT Filed June 20, 1946 Patented Dec. 13, 1949 MANUFACTURE F SEALED LIGHTING UNIT Reginald K. Braunsdorif,

signor to Tung-Soi Lamp Works, Inc., Newark.

N. J., a corporation of D East Orange. N. J., ls-

elaware Application June 20, 1946. Serial N0. 678,070 19 Claims. (Cl. 17H4),

This invention relates to electric lamps and particularly to sealed lighting units comprising glass reflector and lens elements with the lighting filament or filaments sealed inside the reflector lens unit.

One object of the invention is a novel and improved lamp of this general character.

A further object of the invention is a novel and improved method of manufacture of a lighting unit of this general character.

A conventional lamp of the above indicated character comprises a reflector and lens assembly of Pyrex glass with the filament or filaments mounted in the desired focal relation with respect to the reflector upon supporting wires or posts passing through and sealed to the refiectcr. A conventional filament support is in the form of an assembly of a post having an alloy cup brazed thereto with the flange of the cup embedded in the softened Pyrex glass about the opening through which the post or rod passes into the rear of the reflector.

In tire manufacture of these conventional lamps the peripheral edges of the reflector lens are heated to the high temperatures required for fusing and ioining the two elements and carbon rollers are utilized to shape or prevent too great a distortion of the peripheral edges during this high temperature fusing operation, but the reiiector elements often become distorted from their true parabolic or other desired contour due to the softening of the glass for the attachment of the filament supporting posts and due to the imperfect shaping of the carbon rollers. Likewise the cover or lens element tends to lose its shape under the softening temperature. Also the high temperatures are injurious to the reflecting surface applied to the inside ol' the reflector element, requiring special precautions in the application of the heating flames and the protection of the reflecting surface. These and other manufacturing steps of the conventional lamps are comparatively expensive operations, and the filaments must be precision mounted upon the supports after the supports are sealed into the reflector which requires expensive filament mounting equipment.

A further object of the invention is a lamp which may be economically manufactured without subjecting the glass of the reector and the lens to the high softening or fusing temperatures with resultant freedom from distortion of the glass element contours and with injury to the reflecting surface minimized.

A further object of the invention is a novel and improved method of sealing and securing the lens and reflector elements in the desired relation.

A further object of the invention is a novel and improved method of sealing the nlament supports into the reflector-lens unit.

A further object of the invention is an improved structure and method of manufacture of a sealed lighting unit whereby the filament mount may be formed as a unit and the filament precision mounted thereon prior to mounting within the reflector. with the filament being precision mounted with respect to the reflector by the mere act of assembling and attaching the elements together.

A further object of the invention is a lamp unit of the above indicated character which is characterized by an improved and simplified iliament mount.

A further object of the invention is a lamp oi' the above indicated character whose reflector and lens elements may be made of those less expensive glasses known in the trade as soft glasses such, for example, as lead glass, lime glass, etc., which also lends itself to lower working temperatures and is capable of molding with greater precision in lens and reflector contours.

A further object of the invention is a lamp ofthe above indicated character which is characterized further by the simplicity of its structure, the economy with which it may be manufactured and by its ability to stand up and withstand the rough usage to which lamps of this general character are subjected.

Further objects of the invention will hereinafter appear.

For a better understanding of the invention, reference may be had to the accompanying drawings, wherein Fig. l is a diagrammatic view illustrating the application of the invention to the sealing and fastening together of a glass reflector and a cover or lens at their peripheries;

Fig. 2 is a diagrammatic view of another embodiment of the invention;

Fig. 3 is an exploded view of the unitary mount shown in Fig. 2; and

Fig. 4 shows an exploded view of a modified unitary mount.

I have illustrated the invention as to the manufacture of sealed lighting units comprising a glass reector and a cover or lens as, for example, of the generally conventional type used in head lamp projectors for automobiles. Referring to Fig. l. such a reflector is indicated at amarre I and a cover or lens at 2. In the conventional practice the glass reflector I and the lens 2 are of Pyrex glass and are fastened and sealed at their peripheries by melting or fusing the peripheries of the elements together. This practice has the disadvantages above enumerated.

I have found that the disadvantages oi' the conventional practice may be obviated or minimized by rst metallizing the adjoining surfaces of the reflector and the cover and then joining and sealing the elements together at their abutting metallized surfaces by employing a low melting point soldering material which melts at a temperature so low as not to set up any appreciable strains in the glass elements. In accordance with the specific embodiments illustrated in this application, I am able to obtain solderable abutting surfaces by first applying or fusing a silver coating to the abutting surfaces to be joined. This step consists of a partial reduction from silver oxide io silver metal. After this base of silver is formed a suitable solderable metal coating is applied thereto and in the embodiments herein shown I utilize copper as the metal to be applied to the silver base. This layer of copper is, for example, deposited electrolytically on to the silver base. The metallized surfaces thus formed on the reflector and cover or lens elements are then tinned, ready for later fastening and sealing the elements together at their peripheries. A low melting point solder for tlnning the metallized surfaces may be used such, for example. as a true eutectic such as 63/3'1 which has a. melting point of around 358 F. The glass elements may be processed at this low temperature without creating excessive strain therein and moreover the precision pressed blass elements are not heated to a temperature high enough to distort them.

In the embodiment of Fig. l the step of metallizing the reflector I is indicated at A. This metallizing of the interior of the reflector may be done in any conventional manner and need not be described. The metallizing of the peripheral surfaces of the glass elements I and 2 to be joined e is illustrated in steps B and C. In step B the abutting surfaces 3 and l of the elements I and 2 to be joined and sealed are provided with silver coatings. This silvering may be effected in any suitable manner as, for example, by utilizing the conventional silver paste such as put out by Du Pont, which paste is applied to the surfaces to be joined after which they may be dried in an electric oven at a low heat, say around 300 F. The glass elements I and 2 may then be subjected to higher temperatures for a short time to cure the silver coating or to effect the partial reduction of the silver oxide to silver metal, after which the glass elements are gradually cooled. After the curing of this silver coating base for the reception of a metallic copper coating the silver base may then be copper-plated by using a copper anode and a carbon cathode in contact with the silver. This step is illustrated in step C of Fig. l. The tlnning of the abutting surfaces 3 and I of the elements is illustrated in step D of Fig. l. After the-abutting surfaces 3 and Il of the elements I and 2 are thus prepared the elements are assembled together in adjoining relation as illustrated in step E of Fig. l. Here the unit I, 2 is heated in any suitable manner or the periphery is heated to a temperature high enough to eifect the fusing of the soldering material, this temperature being not only below the melting temperature of the glass of the elements I and 2 but also well below the strain point ci' the glass employed which is preferably a soft glass as. for example, lime or lead glass although other glass may be employed.

In the embodiment of Fig. l the reilector I is provided with any conventional terminals leading to the filament or filaments in the reector. In the particular embodiment shown there are three such terminals shown. as indicated at 5. for supplying current to a two-filament mound. A conventional exhaust tube B is indicated also for exhausting the sealed unit. In step F the unit is illustrated as being furnished with a base 1;

In the embodiment of Fig. 2 the reflector element I' is provided at its apex with an opening III and around this opening III the reflector is provided with an abutting fastening annular surface II for the reception of a button or precision mount unit I2 having an annular abutting surface I3 which is adapted to engage and be Ioined to the reflector element I at its annular abutting surface II. The abutting surfaces II and I3 are metallized and tinned as above described to prepare them for fastening and sealing the unit I2 to the rear of the reflector I', these prepared surfaces being indicated at I3' and II', respectively. In like manner the abutting surfaces 3 and 4 of the reflector and the cover or lens are prepared, the prepared surfaces being indicated at 3' and l', respectively. The three elements 3, 4 and I2 may be assembled and joined together simultaneously by subjecting them to heat at a temperature sufcient to fuse the tinned or soldered surfaces while the elements are held firmly together or the elements 3 and I2 and` the elements 3 and 4 may be thus joined at different times as may be convenient. The button unit I2 may have its filament or filaments precision mounted thereon prior to the fastening of the button unit to the reflector element I'. This may be effected by mounting the filament upon the filament supports in a predetermined relation with respect to the abutting surfaces I3 and another reference point on the outer periphery of the button, the arrangement being such that when the unit is applied to the rear of the reflector and fastened to the abutting surface II in predetermined relation thereto the filament or filaments are mounted in the correct focal position with respect to the reflector by the mere act of assembling and fastening the two elements together. If the filament or filaments are not precision mounted on the unit I2 they may be precision mounted after the assembly and fastening of the unit I2 to the reflector I and after the precision mounting oi the filament or filaments the cover or lens 2 may be then joined to the reflector I' in accordance with this invention.

Fig. 3 shows an exploded view of the elements of the button mount I2 shown in Fig. 2. In this embodiment there is only a single filament I5 with two mount support rods or wires I6 and I'I with the ends of the rods or support wires passed through openings I1 and I6' formed in the rear of the button I2'. The button I2' is provided with an opening IB for the reception of an exhaust tube III. The exhaust tube I8 may be fastened and sealed in position by wetting glass to glass or it may be sealed thereto in accordance with my invention as set forth in application. Serial No. 590,321, now abandoned, and in application, Serial No. 637,684. The two leads I6 and I1 may be attached in position in any suitable manner as, for example, by the conventional method of melting glass. With the button I2' como of soft glass as, for example. lime glass. the leads Il and i1 may be of a suitable alloy and designed for either outside insertion or inside insertion. As described above the filament I5 may be precision mounted on the leads Il and I1 by mounting it in predetermined relation with respect to the abutting surface Il and a diameter of the button.

In Fig. 4 is illustrated a modification wherein the leads or filament support wires are provided, having heads 20' and flanges 2i. These leads are inserted from the outside or from the rear of the button through the openings Il' and il' and the flanges or shoulders 2i are fastened to the protruding glass sections forming the openings It' and Il'. This fastening may, for example, be effected by the fastening method of the invention as above described.

The invention permits a variation in coeflicients of expansion for different materials such as different glasses. This could also be from glass to metal or to suitable alloys. Other advantages of the invention are indicated above such, for example, as the fastening and sealing of the glass elements together without distortion from their pressed forms and with the minimum of' glass strains being set up in the reflector and cover elements. The whole manufacturing process according to this invention is considerably simplifled as compared with the conventional practice and the softer and less expensive glasses such as lime and lead glass may be use'd and moreover notwithstanding their relatively high expansion coeiiicients.

This is a continuation in part of application, Serial No. 590,321, filed April 26, 1945, and application. Serial No. 637,684, flied December 28, 1945.

I claim:

l. The method of making a sealed lighting unit formed of a glass reflector and a glass cover or lens which comprises the steps of providing a firmly adhering layer of solderable metal upon the abutting and joining edges of the glass elements and then soldering the glass elements together at said abutting surfaces with a solder which melts at a temperature well below the melting point of the glass of the reflector and cover.

2. The method of manufacturing a sealed lighting unit formed of a reflector element and a glass cover or lens element comprising the steps of metallizing the peripheral abutting surface of the cover element with a solderable metal and then fastening the cover element to the reflector element by soldering the metallized abutting surface of the cover or lens element to a correspondlng metal abutting surface of the reflector element with a solder which melts at a temperature well below the melting point of the glass of the reflector and cover.

3. The method of manufacturing a sealed lighting unit formed of a reflector element and a glass cover or lens element comprising the steps of applying and aifixing a silver base to the peripheral abutting surface of the cover or lens element, then electroiytically applying to said silver base a layer oi copper and then soldering the cover element to the reflector element at the abutting surface of the cover element thus metallized with a solder which melts at a temperature well below the melting point of the glass of the reflector and cover.

4. The method of manufacturing a sealed lighting unit formed of a reflector element and a glass cover or lens element comprising the steps of applying to the peripheral abutting edge of the cover or lens element a firmly adhering base for the reception of a solderable metallic coating, then applying a solderable metallic coating to said base and then fastening and sealing said cover element to the reflector element by soldering the metallized abutting surface of the cover element to a corresponding abutting metallic surface of said reflector element.

5. The method of manufacturing a sealed lighting unit formed of a reflector element and a glass cover or lens element comprising the steps of applying to the peripheral abutting edge of the cover or lens element a firmly adhering base for the reception of a solderable metallic coating, then applying a solderable metallic coating to said base and then fastening and sealing said cover element to the reflector element by soldering the metallized abutting surface of the cover element to a corresponding abutting metallic surface of said reflector element, comprising the step of externally applying a unitary button mount within an opening formed in the rear of the reflector with the button of the mount and the reflector having abutting surfaces for fastening the two elements ilrmly together.

6. The method of manufacturing a sealed.

lighting unit formed of a glass reflector element and a glass cover or lens element comprising the step of forming on said elements corresponding and abutting surfaces metallized with a solderable metal and then soldering the elements together at the metallized surfaces with a solder having a melting point below the melting and strain points of the glass.

l. The method of manufacturing a sealed lighting unit formed of a glass reflector element. a glass cover or lens element and a unitary illament mount element comprising the steps of metallizing abutting fastening surfaces of the elements with a solderable metal and after the forming of such metallized surfaces soldering the mount element and the reilector element at their metallized abutting surfaces and soldering the cover element and the reflector element at their corresponding metallized surfaces.

8. The method of manufacturing a sealed lighting unit formed of a reflector element and a glass cover or lens element comprising the steps of applying a layer of silver oxide to the peripheral abutting and fastening surface of the cover or lens element, heating said element, treating it at a temperature of from 200 to 300 F. and then applying for a short period a higher temperature, then electrolytically applying to the silver base thus formed a layer of a solderable metal and then soldering the cover element to the reflector element at the abutting surface of the cover element thus metallized.

9. A sealed lighting unit comprising a reflector element and a glass cover or lens element of soft glass, and an incandescent filament therein, said glass cover or lens element being fastened and sealed to the reflector element at their peripheries by means of a metallized soldered joint.

10. A sealed lighting unit comprising a reilector element, a. glass cover or lens element and a unitary mount element, said glass cover or lens element being fastened and sealed to the reflector element at their peripheries by means of a. metallized soldered joint and said mount element being fastened and sealed to the reflector element by means of a similar metallized soldered joint.

1l. The method of making a sealed projector lighting unit -comprising a reflector. an incandescent fllament mounted in the reflector and a cover or lens, which comprises the steps of forming the reflector and the cover elements of a soft glass, applying to the abutting and adjoiningperipheral edges of the glass elements firmly adhering layers of solderable metal and then soldering the glass elements together at said abutting surfaces with the solder disposed therebetween having a melting point well below the melting and strain points of the glass of the elements. y

12. The method of making a sealed projector lighting unit having a reflector, an incandescent filament mounted therein and a cover or lens therefor which comprises the steps of forming the reflector and cover elements of a soft glass, applying to the abutting and adjoining peripheral edges of the reflector and cover elements a firmly adhering base of silver for the reception of a solderable metallic coating thereon, then applying layers of copper to sald bases and then fastening and sealing said cover and reflector elements by soldering the metallized abutting and adjoining surfaces thereto with a. solder having a melting point below the melting and strain points of the soft glass.

13. The method of making a sealed projector lighting unit formed of a reflector, an incandescent fllament mounted therein and a cover or lens which comprises the steps of forming a filament mount support element, the reflector element and the cover element of soft glass with the reflector element having an opening therein for the reception in abutting relation of the filament support, applying to the abutting and adjoining peripheral edges of the reflector and the cover element and to the abutting and ad- Joining surfaces of the reflector and the filament support element firmly adhering layers of solderable metal and then simultaneously soldering the elements together at their abutting surfaces with a solder which melts at a temperature well below the melting point of the glass of the elements and also below the critical strain points of the glass.

14. The method of making a sealed projector lighting unit having a glass reflector and a glass cover or lens therefor of pre-pressed contour which comprises the steps of applying to the abutting and adjoining peripheral edges of the reflector and cover elements to be joined a firmly adhering base for the reception of a solderable metallic coating thereon, then applying solderable metallic coatings to said bases and then joining and sealing said cover and reflector elements by applying to the abutting surfaces a solder having a melting point substantially below the softening point of the glass of the reflector and cover elements and then heating the peripheries with the soldering material therebetween to a temperature below the softening point of the glass but high enough to fuse or melt the solder with the glass elements pressed together, whereby the reflector element and the cover element are sealed at their peripheral edges and firmly joined thereat into a rigid unitary structure with the contours of the elements retaining their original pre-pressed form.

15. The method of making a sealed projector lighting unit having a reflector and a glass cover or lens therefor of pre-pressed contour which comprises the steps of applying to the abutting and adjoining peripheral edges of the reflector and cover elements to be joined a firmly adhering base for the reception of a solderable metallic coating thereon, then applying solderable metallie coatings to said bases and then joining and sealing said cover and reflector elements by applying to the abutting surfaces a solder having a melting point substantially below the softening point of the glass and then heating the peripheries and the soldering material to a temperature below the softening point of the glass but high enough to fuse or melt the solder with the elements pressed togetheer, whereby the reflector element and the cover element are sealed at their peripheral edges and rmly joined thereat into a rigid unitary structure with the contours of the elements retaining their original pre-pressed orm.

16. The method or making a. sealed projector lighting unit having a reector element having a solderable metallic peripheral edge and a glass cover or lens element therefor of preformed contour which comprises the steps of applying to the peripheral edge of the cover element a firmly adhering base for the reception of a solderable metallic coating thereon, then applying a solderable metallic coating to said base and then joining and sealing the cover element and reflector by applying to the coated peripheral edge of said cover or lens element a solder having a. softening point substantially :below the softening point of said cover element, and then heating the periph eries of said elements in abutting relationship with the soldering material therebetween to a temperature below the softening point of said cover element but high enough to melt the solder with the elements pressed together whereby the reflector element and cover element are sealed at their peripheral edges andfirmly joined thereat into a rigid unitary structure `with the contours of the elements retaining their original prepressed form.

17. The method of making a sealed projector lighting unit having a cover element of prepressed contour having a solderable metallic peripheral edge and a glass reflector element therefor of pre-pressed contour, comprising the steps of applying to the peripheral edge of the reflector element a rmly adhering base for the reception of a metallic coating thereon, then applying a metallic coating to said base and then joining and sealing the cover and reflector elements by applying to the coated peripheral edge of said reflector a solder having a softening point substantially ybelow the softening point of said reflector element and then heating the peripherles of said elements in abutting relationship with 'the soldering material therebetween to a temperature below the softening point of said reflector element but high enough to melt the solder with the elements pressed rtogether whereby the reflector element and cover element are sealed at their peripheral edges and firmly joined thereat into a rigid unitary structure with the contours of the elements retaining their original 'pre- `pressed form.

18. The method of making a sealed projector lighting unit having a glass reflector and a glass cover or lens therefor of pre-pressed contour which comprises the steps of applying to the abutting and adjoining peripheral edges of the reflector and cover elements to be joined a firmly adhering base for the reception of a solderable metallic coating thereon, then applying solderable metallic coatings to said Abases and then joining and sealing said cover and reflector elements by applying to :the abutting surfaces a solder having a melting point substantially below the soitening point of the glass of the reilector and cover elements and then heating the peripheries and the soldering material to a temperature below the softening point of the glass but high enough to fuse or melt the solder with the glass elements pressed together, whereby the reflector element and the cover element are sealed at their peripheral edges and iirmly joined thereat into a rigid unitary structure with the contours ofthe elements retaining their original pre-pressed iorm and fastening and sealing to the reflector a unitary button mount having a precision mounted filament, said mount and glass reilector having corresponding abutting :fastening surfaces.

19. The method of making a sealed projector lighting unit having a reflector and a glass cover or lens therefor oi' pre-pressed contour which comprises the steps of applying to the abutting and adjoining peripheral edges of the reiiector and cover elements to be Joined a firmly adhering base ior the reception of a solder-able metallic coating thereon, then applying solderable metallic coatings to said bases and then joining and sealing said cover and reector elements by aprplying to the abutting surfaces a solder having a melting point substantially below the softening i0 :point of the glass and then heating lthc peripheries with the soldering material in situ to a tem- .perature -below the softening point o! the glass but high enough to inse or melt the solder with ithe elements pressed together, whereby the reilector element and the oover element are sealed at their peripherai edges and rmly joined thereat into a rigid 4unitary structure with the contours of the elements retaining their original prepressed form, and fastening and sealing to the reilector a unitary -button mount having a precislon mounted lament, said mount and reieetor having corresponding abutting fastening surfaces.

REGINALD K. BRAUNSDORFF.

REFERENCES CITED The following references are oi record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 507,890 Doulton et al Oct. 3l, 1893 1,852,093 Smede et al Apr. 5, 1932 2,149,246 Zimmerman Feb. 28, 1939 2,169,194 Geyer et al Aug. 8, i939 2,236,911 Long Apr. 1941 2,362,173 Swanson Nov. 7, 1944

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