US2082954A - Prefocused lamp base - Google Patents

Description

June 8, 1937 D. s. Gus-11N I PREFOUSED LAMP 'BASE Filed Deo. 1,6,` 1935 ATTORNEY INVENTOR f- ..`5'. 6057"/ v1.iil Mu nl BYM Patented June 8, 1937 PnErooUsEn LAMP BASE Daniel S. Gustin,I East Orange, N. J., assixnor, by mesne assignments, to Westinghouse Electric and Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania t Application December 16, 1933, Serial No. 702,691

9 Claims.

This invention relates to electrical devices and particularly to an incandescent electric lamp A in which the light source is disposed in a predetermined position relative to other parts ofthe device.'

Certain types of electric incandescent lamps termed precision lamps are used with special holding means to position the filament of the lamp on a given focal line as in the most effective position with respect to a reiiector. The light source of the lamp must be accurately located and since it is necessary to interchange or replace a burned out lamp with a new lone it is important that the lamps are so manufactured that the illament in each lamp occupies the same relative position.

Heretofore lamps have been made with the usual manufacturing accuracy and means have been provided in the sockets or holders for the necessary adjustment. In other cases the usual brass shell/base has been used and adjusted prior to permanent attachment to thebulb or a ilanged ring has been used which ring was sol-r the course of manufacturing large quantities oi?l lamps that some lamps will be produced in which the iilaments are located with a considerable degree of accuracy but in order to insure a more uniform product in the form of alamp which may b'e used for optical purposes it is lnecessary that each lamp be so constructed that the illament will be positively positioned with respect to another point on the bulb or base ofthe lamp.

An object of the present invention is, therefore, to provide a method of manufacturing an incandescent electric lamp in such a manner as to meet the usual practice in lamp production and produce a lamp with the illament definitely positioned with respect to the base of the bulb. Another object of the invention is to provide va lamp with a base oi' molded material so formed as to provide a surface in predetermined relation to the lamp iilament. .I

Other objects and advantages of the invention will be more clearly understood by reference to the following description together with the ac-` companying drawing in which Fig. 1 is a side elevational view of a lamp constructed in accordance with the present invention disposed above a'holder or socket; 5

Fig. 2 is an enlarged sectional view of the lamp shown in Fig. 1 but positioned in a holder or socket;

Fig. 3 is a view looking toward the bottom of the lamp; I 10 Fig. 4 is a cross-sectional detail view of a mold for forming a base in accordance with the present invention;

Fig. 5 is a view partly in cross section showing a bulb .in position to have a base molded thereon 15 and Fig. 6 is a view similar to Fig. 5 but shows the molding material disposed about the bulb to form a base. v

Although the present invention is particularly 20 desirable for the manufacture of a'lamp with the filament denitely positioned with respect to a given surface or projection on the base it may also be applied to the manufacture of lamps of other types or may be practiced for providing 25 a base for vacuum devices in general where it is desirable to provide a base of insulative material.

As illustrated in the drawing the present invention may be employed to provide a base for 30 a lamp to be used as a light source for an automobile headlight.

As shown, a lamp of this character may comprise a bulb I0 provided with a lament I I having its terminals secured to the ends of conductive 35 support wires I2 and I3. These support wires extend through a press I4 (see Fig. 2) and from the bulb in the form of extensions orlead wires I5A and I irespectively.

These lead wires are connected to contact 40- wires to the contacts.

Incandescent electric lamps as commonly constructed include a are tube I1 which extends into the bulb, carries the press I4; and is sealed 50 I at IB tothe neck of the bulb, a tube I9 being provided for the purpose of exhausting the bulb. It is the practice in lamp manufacture to provide a mount which includes the flare tube having support wires .containing lead wires sealed 55 through the press, and having a filament secured to the support Wires. This mount is then supported and a bulb is disposed so that its neck surrounds a flanged portion of the flare tube. Heat isvthen applied and the flare tube sealed to the bulb, leaving a bead or annulus 2l The sealing-in operation is performed with as much accuracy as is possible under high speed conditions and the lament located in a denite position Within relatively narrow limits. When a base is applied to the bulb, however, it is not always possible to exactly position it a definite distance from the filament, nor is it possible to provide bases, unless special care is exercised, which do not have variations in their physical dimensions. Auxiliary means as above mentioned must, therefore, be provided to cooperate with a socket or holder to properly locate the filament. l

In accordance with the present invention a base is provided by molding 'from a suitable insulative material and during the molding of the base a surface is rprovided a definite distance from the filament, which surface cooperates with a holder or socket to locate the filament in proper focal relation with a reflector or other optical system.

As shown in Figs. 4 to 6, a mold 22 may be provided, including a chamber 23 in which a plunger 24 is disposed for movement along the longitudinal axis of the chamber. The plunger may be provided with apertures 25 and 26 to receive tubular contact members 21 and 28. apertures may be enlarged to receive and seat the contacts, Which latter may have enlarged ends or heads which project above the upper end of the plunger. terial may be placed in the chamber above the plunger and may be so formed as to provide space for the ends of the contacts. The moldable material may be of such character that before curing by heat it is in the form of a plastic mass and the chamber 23 may be provided with a steam jacket 3l into which live steam is admitted to set or cure the moldable material after it has been shaped by pressure resulting from a movement of the plunger 24.

A sealed-in bulb I0 may be disposed, as shown in Figs. 5 and 6, with the neck thereof inserted into the upper end of the chamber 23 and may be held by jaws 32 and 33 and pressure cap 34. The chamber may be provided with an annular recess 35. The lead wires l5 and I6 may be threaded into the contacts and extend into the apertures in the plunger. The plunger may then be moved to compress the moldable material into the form of a base, as shown in Fig. 6,

`at which time the heads of the contacts become embedded and thus secured in the moldable material when heat is applied and the material has hardened. The bead 2l holds the bulb securely to the base. If desirable, the bulb may have depressions or protuberances formed in the glass to insure a more secure hold.

The base, by reason of the annular recess 35, is provided with a shoulder 36, the -lo-wer surface 31 of which may be a denite distance from the light source I|.` 'Ihis surface cooperates with a surface 38 of a holder or socket 39 and contact 21 may have a notch 4I to engage a tension member 42 on the holder which maintains the surface 31. of the base against the surface 38 of the holder. The contact 28 may engage another contact insulated from the tension member. The holder shown is given one means of The' A pellet 29 of a moldable maholding the lamp having the present form of base, but it is obvious that the construction of the holder may vary to meet the requirements of the particular type of equipment in which the lamp is to be used.

It will be evident that, when molding bases onto the necks of bulbs, variations may occur causing the bulbs to be held at slightly different positions in the mold depending on the accuracy of the diameter of the bulb at the contact surface M Where it seats on the mold. 'I'he recess which forms the shoulder is, therefore, so arranged `that the distance X between the light and the shoulder on the base resulting from the recess, is greater than the distance required. When the bulb has been provided with a base it is supported for rotation and a tool d5 is employed to trim material from, the shoulder until a surface on the base is provided at a predetermined distance from the light source. 'Ihe trimming operation may be made with optical means 46 so that an operator may trim oil the proper amount of material.

The lamp may, however, be used in a socket or holder in whichv a xed surface is provided to engage the bottom surface 4l of the base. In this case the plunger may be so controlled that the distance Y is a predetermined dimension. As above pointed out the lamps are made with a. considerable degree of accuracy and it is only necessary to vary the surface on the base a very small fraction of an inch usually between e and V64 of an inch so that the plunger may press the moldable material to form a complete base but may be arrested during the compressing operation so that the bottom surface of the base is located a predetermined distance from the light source.

When forming the base to provide the surface d1 in the required relation to the light source, suitable optical means may be employed such for example as shown in my Patent 1,760,693 issued May 27, 1930. It will be evident that by reason of the present method of forming a base on a bulb the bulb may, prior to the molding operation, be adjusted laterally to bring the lament into vertical focal position.

When a lamp with a base molded thereon is removed from the mold the lead wires may be cut olf `flush with the ends of the contacts and soldered thereto.

The lamp is then ready to be used with any reector or optical system wherein the most advantageous results are obtained when the light source is in a definite position with respect to a given focal line.

Although a preferred embodiment of the invention 1s shown and described herein it is to be understood that modifications may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. An incandescent lamp comprising a bulb, a :lamentin said bulb, a base entirely of material molded around the neck of the bulb, said base being shaped to fit a socket and to provide an external surface of said molded material a predetermined distance from said lament, and contact members embedded in said molded material and adapted to cooperate with said socket to hold said surface in engagement with a positioning surface on said socket.

2. An incandescent lamp comprising a bulb, a filament in said bulb positioned with the usual commercial accuracy, a base of material molded around the neck of said bulb, said base having a shoulder of said molded material formed thereon a predetermined distance from said filament and extending as an annular surface entirely therearound, said shoulder being adapted to engage with a socket member and to position the filament in a definite space relation thereto, and contact members embedded in said molded material for holding said shoulder in place against a corresponding surface on said socket member, by en.

`from said molded material and adapted to engage means carried by said socket member for holding said shoulder in engagement with said socket member.

4. An incandescent lamp comprising a bulb, a filament in said bulb positioned with the usual commercial accuracy, a base of material molded around the neck of said bulb, said base being shaped to fit a socket member and having a contact portion formed of said molded material, so disposed with respect to said filament as to cooperate with means on 4said socket member to hold the filament in a predetermined position relative to said socket member, and conductive contact means extending longitudinally from the lower surface of said base and adapted to secure said lamp in position in said socket member by engaging a portion thereof.

5. The method of basing a lamp bulb having a filament positioned with the usual commercial accuracy which comprises forming contact members, forming a locking surface on at least one ofsaid contact members, shaping moldable material about the bulb neck to form a base, pressing f a surface on said base during the shaping operation a predetermined distance from said filament and simultaneously embedding the ends of said contact members in said material.

6. The method of basing a lamp bulb having a lament therein and lead wires extending from the neck thereof which comprises forming tubular contact members, making a notch in one of said members for engagingy means for holding said bulb in position, threading the lead wires into said members, compressing moldable material about said bulb neck to form a base while embedding the ends of said contact members, and during the shaping operation forming a surface on said base a predetermined distance from said filament.

7. vThe method of basing a lamp bulb having a filament positioned with the usual commercial accuracy which comprises supporting a bulb, forming conductive contact members, making a notch in at least one of said members for interlocking with an associated lamp socket, shaping moldable material about said contact members and bulb neck to form a base, adjusting the bulb with respect to the moldable material during the shaping operation to locate the filament in a predetermined position with respect to a surface formed during the shaping operation on said base, and permitting said material to harden to provide a surface to engage with asurface on said socket member to hold the filament in a desired relation with respect thereto.

8. The method of basing a lamp bulb having a lament positioned therein with the usual commercial accuracy which comprises, forming contact members and shaping at least one so as to lock said bulb in place, and shaping moldable material around the bulb neck and contact members so Athat an annular shoulder is provided extending entirely around said base and adapted tof engage the edge portion of a receiving socket.

9. The method of basing a. lamp bulb having a filament therein positioned with the usual commercial accuracy which comprises, shaping moldable material about the bulb neck to form a .from said shoulder, while observing the position of the lament. until said shoulder is positioned and at the `proper distance from said filament,

so that when the base is fitted in a receiving sock? et the filament will be disposed in the desired i location.

DANIEL s. GUSTIN.

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