US3005175A

US3005175A - Spring blades for recessed end fluorescent lampholder

Info

Publication number: US3005175A
Application number: US764908A
Authority: US
Inventors: John M Pistey
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1958-10-02
Filing date: 1958-10-02
Publication date: 1961-10-17
Anticipated expiration: 1978-10-17

Description

J. M. PISTEY Oct. 17, 1961 SPRING BLADES FOR RECESSED END FLOURESCENT LAMPHOLDER Filed 00'0- 2, 1958 [/71 6/7/0/ Job/7 M P/s/fy H/LS A 170mg 3,005,175 1C Patented Oct. 17, 1961 3,005,175 SPRWG BLADES FOR RECESSED END FLUORESCENT LAIVHHOLDER John M. Pistey, Fairlield, Conn, assignor to General Electric Company, a corporation of New York Filed Oct. 2, 1958, Ser. No. 764,908 3 Claims. (Cl. 339-50) The present invention relates to an improvement in the spring contact blades for fluorescent lampholders of the general type shown in my earlier Patent No. 2,716,738.

Previous recessed contact lampholders have included a cam-shaped contact tab and either an elaborate spring with an integral terminal end or a coiled spring that is seated on a separate terminal strip.

The principal object of this invention is to reduce the number of parts and increase the ease of assembly of a fluorescent lampholder with recessed contacts by providing novel contact blades of unitary construction.

A further object of this invention is to provide novel spring contact blades for a recessed end fluorescent lampholder to obtain a triple wiping action with the contacts of a lamp.

The present invention is primarily concerned with the stationary end of a set of lampholders where the movement of the lampholder contacts is relatively slight as the lamp base is being inserted into the lampholder. The o-pposite l-ampholder is a telescopic lampholder for the high voltage end of the lamp where a greater travel of a lampsupporting plunger is required, necessitating the use of elongated coil springs.

The unitary spring contact blades of this invention are of flat resilient material that is bent flatwise into a generally Z-shape where the base of the Z-shaped contact represents a fixed terminal end. The shank of the contact is a spring portion that resiliently supports the top cam portion of the contact. In the preferred embodiment of this invention, the shank of each contact is inclined upwardly and rearwardly from the terminal end of the contact as well as sidewise slightly toward the other contact. The cam portions of the contacts are separated by an amount so that when a lamp base is inserted into the lampholder, the cams will be pressed slightly toward each other as well as inwardly of the housing. Concurrently, the cams will pivot on the shanks of the contacts from the fixed terminal ends thereof and move in an are that is traced upwardly and rearwardly from the normal position of the cams to give a triple wiping action with the contacts of the lamp.

My invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

FIGURE 1 is an exploded view of a fluorescent lampholder with recessed contacts, showing the novel unitary contact blades of the present invention.

FIGURE 2 is a side cross-sectional view of the lampholder of FIGURE 1 taken in a vertical plane on the lines 2-2 of FIGURE 5.

FIGURE 3 is a front elevational view of the back cover plate of the lampholder, showing the pair of contact blades with their terminal ends fixedly mounted in the cover.

FIGURE 4 is a top plan view of the cover plate of FIGURE 3, showing the relative positions of the cam ends of the cont-act blades.

FIGURE 5 is a rear view of the recessed base of the lampholder which is assembled with the back cover plate to form a hollow housing for the lampholder.

Referring in detail to the drawing and in particular to the exploded view of FIGURE 1, there is shown a recessed base member 10, a back cover plate 11, and a pair of unitary electrical contacts 12. The lampholder housing is formed by placing the cover 11 over the back of the base 10 and threading a screw (not shown) through the front opening 13 of the base into the opening 14 of the cover. A lamp base-receiving recess 15 is formed in the front wall of the base. A transverse partition 16 establishes the back wall of the recess. A pair of coplanar slots 17 extend through the partition for communicating with the interior of the housing. A divider 18 is located within the recess between the slots 17 for insulating the contacts 12 from each other.

The interior of the base 10 can be best understood by referring to FIGURES 2 and 5. Curved walls 19 form separated

chambers

20 and 21. The lower wall 22 cooperates with the cover plate 11 to establish a Wiring compartment 23 in the bottom of the lampholder. Considering the cover plate 11, as seen in FIGURE 1, it is primarily a flat plate 25 with a large vertical partition 26 and a pair of side abutments 27.

The design of the lampholder housing as described above is more or less conventional. The nucleus of the present invention is represented by the pair of spring contact blades 12. In the preferred embodiment of this invention, both blades are identical in function and structurally similar, one of the blades being for the right side of the larnpholder and the other being for the left side. Accordingly, the same reference numerals will apply to both blades. Each contact blade is of generally Z-shape where the base 30 of the Z-shape is the terminal end of the contact. This terminal end 30 is provided with a tapped opening 38 for receiving the terminal screw 39. The opposite sides of the terminal end are lanced to provide springing sections 31 for tight-fitting engagement in the opposed grooves 32 in the sides of the partition 26 and abutments 27, as is best seen in FIGURE 1. Thus, the contact terminal 30 is rigidly supported in the lampholder housing. The shank 33 of the Z-shaped contact represents a spring portion that pivots about its lower end on the terminal 30. The top 34 of the Z-shaped contact constitutes a cam that is generally parallel with the terminal base 34). The leading edge 35 of the cam is of stepped configuration formed by a tongue 36 and a side surface 37. The cam is adapted to extend through the slot 71 in the partition 16 of the recess as is best seen in FIGURE 2.

The terminal base 30 of the contact is of such length that when the cover 11 is fitted to the base 10, the lower wall 22 of the base 10 will engage the contact as at 40 and clamp the terminal end in place. During assembly, the shank 33 of the contact is slightly deflected backwardly so that the contact cams are spring biased outwardly of the recess 15. Now turning to a consideration of the top plan view of FIGURE 4, the shape of the contact cams 34 can be readily recognized. The outer side edges of tongues 36 of the cams are spaced apart by a distance that is greater than the spacing of the recessed contacts of the lamp. Hence, as the lamp base is inserted into the lam-pholder, the lamp contacts will first strike the tongues 36 and move the cams both inwardly of the housing and inwardly toward each other. Looking at FIGURE 2 of the drawing, it will be understood that as the cams move inwardly of the housing, the shanks 33 of the contacts will pivot about their lower ends, moving the cams in an arc that is traced from the fulcrum of the shanks. Accordingly, during the insertion of the lamp base, the contact cams will move in three directions, namely, toward each other, inwardly of the housing, and in an are that is struck from the lower pivotal end of the contact shanks. This triple movement of the contact cams causes the lamp contacts to wipe the front and side of the tongue 36 and also to wipe the side surface 37, thereby efiecting a triple wip ing action.

This unitary spring contact construction brings about several marked improvements over the lampholder designs of the prior art. First, it cuts down on the resistance of the circuit through the larnpholder by eliminating the spring biasing connection between the coiled springs of the lampholder, the contact tabs and the terminal blades. These three elements are combined into one member that is both easy to manufacture and assemble. Secondly, this novel contact blade introduces a Wiping action in an additional plane to give a triple wiping action. Thirdly, the contact blades of the present invention retain a side wipe of the contact earn by a twisting action in the long shank of the contact. The central partition 26 in the cover prevents the shanks of the contacts from moving sidewise, thereby forcing them to twist and give a more even action of spring resistance. Fourthly, and quite obviously, this improved design is a cost reduction over the previous designs that have as many as four additional parts to manufacture and handle during assembly.

Modifications of this invention will occur to those skilled in this art and it is to be understood, therefore, that this invention is not limited to the particular embodiments disclosed but that it is intended to cover all modifications within the true spirit and scope of this invention as claimed.

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

1. A fluorescent lampholder comprising a housing with a recess in the front face for receiving a portion of a lamp base, a transverse partition forming the back Wall of the recess, a pair of coplanar slots formed in the partition; the invention comprising a pair of unitary electrical contacts of fiat resilient material, each contact being bent fiatwise into a Z-shape, the base of each Z-shaped contact representing the terminal end, the shank of each contact being a spring portion, and the top of each contact being a cam portion for making electrical connection with the contacts of a lamp, each contact base being fixed in the housing, while each cam portion extends through one of the slots and is spring supported therein by the shank of its respective contact, the cam portions of the contacts be ing separated and disposed with relation to each other so that when a lamp is inserted into the recess of the housing, the cam portions will cooperate With contacts of the lamp thereby be pressed slightly toward each other as well as inwardly of the housin the cam portions also swinging upwardly in an are that is traced from the contact bases to provide a wiping action in cooperation with the lamp contacts.

2. A fluorescent lampholder as recited in claim 1 Wherein the shank of each contact is inclined rearwardly and upwardly from the terminal end to the cam portion.

3. A fluorescent lampholder as recited in claim 2 wher in the shank portion of each contact is also inclined slightly to the side toward the other contact whereby the shank is twisted as the contact cams are pressed together to provide the said wiping action.

References Cited in the file of this patent UNITED STATES PATENTS 2,716,738 Pistey Aug. 30, 1955 2,814,788 Godfrey Nov. 26, 1957 FOREIGN PATENTS 856,181 Germany Nov. 20, 1952