US3124713A

US3124713A - Spring-loaded lamp

Info

Publication number: US3124713A
Authority: US
Publication date: 1964-03-10
Anticipated expiration: 1981-03-10

Description

March 10, 1964 J. A. RANDMER 3,124,713 SPRING-LOADED LAMP FILAMENT SUPPORT Original Filed July 23, 1956 FIG.

INVENTOR JACOB 4. KAI/V0445? Mm. /W

United States Patent 3,124,713 SPRING-LOADED LAMP FILAMENT SUPPORT Jacob A. Randmer, Norwalk, C'onn., assignor to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Original application July 23, 1956, Ser. No. 599,385, now Patent No. 3,003,633. Divided and this application Aug. 28, 1961, Ser. No. 134,319

7 Claims. (Cl. 313-271) This invention relates generally to incandescent lamps provided with a light emitting filament, the invention relating more particularly to means for supporting the filament within the lamp housing.

The invention is disclosed herein in an embodiment adapted for an elongate tubular lamp which may be employed as an infra-red light source for the photo responsive sensing unit of a record controlled business machine. Such a lamp employed for such a purpose is shown and described in the co-pending application of Guillermo Perez, Philip S. Rand and Jacob A. Randmer entitled Record Card Sorting Machine bearing Serial No. 599,385 and filed July 23, 1956, now Letters Patent No. 3,003,633, the present application being a division thereof.

A lamp employed for this purpose must necessarily assume a long tubular shape of a length commensurate with the length of the record card to be sensed or scanned thereby and must also provide a filament of corresponding length in order to illuminate the entire length of the card with an even or uniform degree of light. It has been found that filaments of relatively long lengths have a tendency to sag when heated due to heat expansion. Attempts have heretofore been made to provide means for eliminating the sag of a filament in a tube of this type, said means assuming the form of a spring member connected to one end of the filament for keeping the filament taut under all heat conditions. However, it has been found that even with the provision of a take-up spring connected to the filament, the filament and spring is susceptible to excessive vibration particularly when the lamp is used in equipment prone to vibration such as, for example, the record card sorting machine of the aforesaid copending application. Excessive vibration of the filament impairs the uniform light emitting characteristics of the filament and also tends to put undue and unnecessary strain on the filament adversely affecting its usefulness and long life. The device of the instant application minimizes the amount of vibration which can be set up in the filament by providing a support for the filament at the point where the filament is joined to take-up spring thereby improving the light emitting qualities of the filament and eliminating the strain and wear on the filament which the vibrations would otherwise cause.

It is, therefore, an object of this invention to improve upon the means for supporting a filament in a light emitting lamp of the character-described.

It is a further object of the invention to eliminate or minimize vibration in a filament for a lamp of the character described.

It is a further object of the invention to provide a fila ment support in the lamp of the character described of simplified design, of durable construction and economical to manufacture.

Further objects of the invention together with the features constributing thereto and advantages accruing therefrom will be apparent from the following description when read in conjunction with the drawings wherein:

FIG. 1 is a fragmentary side elevation of one end of a lamp with the envelope partly cut away to show the filament supporting assembly contained therein;

ice

FIG. 2 is a section taken along the lines 2-2 of FIG. 1;

FIG. 3 is a section taken along the lines 3--3 of FIG. 1.

As shown in the drawing, a lamp 400 comprises an evacuated envelope 410 housing a ribbon filament 411, preferably of tungsten or the like, which filament is secured at one end to an external terminal of the lamp (not shown) and at the other end to a plate member 414. The plate 414 is preferably formed of two flat pieces of metal having good conducting properties and joined together, the upper and lower edges of the metal members being spread apart and turned inwardly to provide a substantially round bearing surface by which the plate is slidably mounted on a supporting framework.

The supporting framework comprises a ring member 415 having lugs 416 bent outwardly therefrom for contacting the inner surface of the envelope 410 and thereby supporting the ring 415 concentrically to the axis of the envelope. The ring 415 is made of a material such as will provide the lugs 416 with a limited amount of yield and thereby providing a snug fit of the ring 415 with envelopes of slightly varying diameters and under all heat conditions. The framework also includes a flat plate 417 of electrically conductive material which is secured to the other external end terminal 418 of the lamp. The plate 417 is connected to ring 415 by rods 420 on which rods the plate 414 is slidably mounted.

Plates

414 and 417 are structually connected by a spring 419 preferably of tungsten or the like, and around said spring is a coil of wire 421 formed of good conductive material such as copper or the like suitably joined to

plates

414, 417 so as to provide a primary electrical connection between the' filament 411 and the external end terminal 418.

When the lamp is connected in a circuit and current is passed through filament 411, the filament expands whereupon the spring 419 causes plate 414 to slide along the supporting rods 420 to take up the slack in the filament. It will be noted that the plate 414 serves as a support for the filament 411 at the point where it is mechanically coupled to the take-up spring 419, and since the plate 414 is carried by frame work which at one end is supported rigidly by the external tube terminal 418 and at the other end by a support member 415 snugly fitted to the tube envelope 410, any tendency of the filament and take-up spring to vibrate harmonically or otherwise, as a result of vibrations imparted to the tube envelope, is substantially suppressed. It will also be noted that by providing two support or guide rods 420 for the slidable plate 414, the plate 414 is restricted to a single plane of motion and thereby prevents the filament 411 from rotating with the result that the plane of the filament is maintained in a fixed position in the lamp at all times.

From the foregoing it will be apparent that the invention as herein disclosed and described provides a simple, efiicient and reliable means for supporting a filament within a tubular envelope in such a manner as to maintain the filament taut under the various heat conditions generated by the lamp and also so as to substantially suppress all vibrations which may be set up in the filament from operation of the equipment in which the lamp is employed.

While there has been shown and described what is considered to be a preferred embodiment of the invention, it is of course understood that variations in form could be made without departing from the spirit of the invention, and it is intended therefore that the invention be not limited to the exact form herein disclosed nor to anything less than the whole of the invention as hereinbefore set forth and as hereinafter claimed.

What is claimed and desired to be secured by Letters Patent is:

1. In a lamp of the class described comprised of a substantially evacuated envelope having an elongate filament supported therein and external terminals for connecting the lamp to a power source, means for securing one end of said filament to one of said terminals, a framework disposed within said envelope, said framework including a portion of electrically conductive material secured to said other terminal and another portion in bearing contact with the inner surface of said envelope, a filament support member joined to said other end of the fiiament and mounted to slide along a plane on said framework, yieldable means electrically connecting said support member with the electrically conductive portion of said framework, and means connected to said support member for urging said support member in a direction to stretch said filament.

2. The invention according to claim 1 wherein said framework includes guide rods slide fitted with said support member and disposed to provide a path of movement for said support member in a direction coaxial with said filament.

3. The invention according to claim 1 wherein said framework includes a plurality of parallel guide rods slide fitted with said support member and disposed to provide a path of movement for said support member in a direction coaxial with said filament.

4. The invention according to claim 1 wherein the means for urging said support member comprises a tension spring connected at one end to said electrically conductive portion of said framework and at the other end to said slideable support member.

5. The invention according to claim 1 wherein said other portion of said framework comprises a ring shaped member formed with outwardly bent lugs disposed to yieldably contact the inner surface of said envelope for 4 supporting said ring shaped member concentrically with said envelope.

6. The invention according to claim 1 wherein said means for electrically connecting said support member with the electrically conductive portion of said framework includes a coil of electrically conductive wire and wherein said means yieldably connecting said support member with said framework comprises an expansion spring, said spring being disposed Within the inner diameter of said coil of electrically conductive wire.

7. In a lamp of the class described comprised of a substantially evacuated envelope having an elongate filament supported therein and external terminals for connecting the lamp to a power source, means for securing one end of said filament to one of said terminals, a framework disposed within said envelope, said framework including a portion of electrically conductive material secured to said other terminal, another portion of ring shaped eonfiguration and formed with lugs projecting outwardly therefrom to yieldably engage the inner surface of said envelope, and guide rods interconnecting said portions of said framework, a filament support member joined to the other end of the filament and slidably mounted on said guide rods, said guide rods defining a path of movement for said support member in a direction coaxial with said filament, a coil of electrically conductive wire connecting said support member with the electrically conductive portion of said framework, and a helical tension spring disposed within the bore of said coil of wire and interconnecting said support member with said one portion of said framework for urging said support member in a direction to stretch said filament.

References Cited in the file of this patent UNITED STATES PATENTS 2,672,570 Carlstrom Mar. 16, 1954

Claims

1. IN A LAMP OF THE CLASS DESCRIBED COMPRISED OF A SUBSTANTIALLY EVACUATED ENVELOPE HAVING AN ELONGATE FILAMENT SUPPORTED THEREIN AND EXTERNAL TERMINALS FOR CONNECTING THE LAMP TO A POWER SOURCE, MEANS FOR SECURING ONE END OF SAID FILAMENT TO ONE OF SAID TERMINALS, A FRAMEWORK DISPOSED WITHIN SAID ENVELOPE, SAID FRAMEWORK INCLUDING A PORTION OF ELECTRICALLY CONDUCTIVE MATERIAL SECURED TO SAID OTHER TERMINAL AND ANOTHER PORTION IN BEARING CONTACT WITH THE INNER SURFACE OF SAID ENVELOPE, A FILAMENT SUPPORT MEMBER JOINED TO SAID OTHER END OF THE FILAMENT AND MOUNTED TO SLIDE ALONG A PLANE ON SAID FRAMEWORK, YIELDABLE MEANS ELECTRICALLY CONNECTING SAID SUPPORT MEMBER WITH THE ELECTRICALLY CONDUCTIVE PORTION OF SAID FRAMEWORK, AND MEANS CONNECTED TO SAID SUPPORT MEMBER FOR URGING SAID SUPPORT MEMBER IN A DIRECTION TO STRETCH SAID FILAMENT.