Lamp-Base Assembly

Electric filament-type lamps are customarily manufactured by first fabricating the glass envelope having filaments sealed within and conductors passing through the glass, and then assembling the glass envelope into a base and making electrical connection to contact members. For use in circuit boards, the lamp base has means for attaching the lamp to the circuit board and of camming the contact members into contact with conductive areas on the circuit board. Examples of these types of lamp bases are disclosed in U.S. Pat. Nos. 3,403,370; 3,447,016; and 3,555,341. The requirement for assembling to contact members adds to the cost as well as contributing to intermittent electrical contact.

FIG. 1 shows an exploded perspective view of the components comprising the invention aligned with a mounting hole in a circuit board.

FIG. 2 shows a lamp assembled into its base.

Referring to FIG. 1, an unbased lamp, shown generally at 10, has an upper envelope 12 which may contain filaments or other light-generating elements (not shown) and a lower body 14. In the embodiment shown, the lower body 14 has substantially parallel sides 16a, 16b but may terminate at the base of the upper envelope. Electrical conductors 18a, 18b extend from the lower body 14 and are bent at 20a, 20b to place the axis of the extremities of the conductors 18a, 18b at approximately right angles to the axis of the lamp 10. Two notches 22a and 22b are molded into the lower body 14 during fabrication of the lamp 10. Each notch 22a or 22b forms a concave depression in the lower body 14. The two notches 22a and 22b are located adjacent to opposite lateral edges 24a, 24b of the lower body 14 and extend less than half way across the lower body 14. As will be clear to one skilled in the art in the light of this disclosure, the exact number and shape of the notches 22a, 22b could be changed without departing from the spirit of this invention.

A one-piece molded base, especially adapted for use with the lamp 10 above described is shown generally at 26. As indicated by the dashed line passing along the axes of the lamp 10 and the base 26, the lamp 10 fits into the molded cavity 28 in the base 26 formed by two semi-cylindrical leaves 30a, 30b. The approximately cylindrical upper envelope 12 nests in the cylindrical sector inner surfaces 31a, 31b of the leaves 30a, 30b. The boss 36a fits tightly against the side 16a of the lower body 14 during insertion of the lamp 10 and snaps into notch 22a. A second boss 36b on semi-cylindrical leaf 30b, hidden by other parts, snaps into notch 22b. The engagement of the bosses 36a, 36b in grooves 22a, 22b mechanically retain the lamp 10 in the base 26 against both axial and lateral displacement. Other means for retaining the lamp in the base such as adhesive, either cement or solvent which tackifies the material of the base, may be used to retain the lamp in the base. Furthermore, the lamp may be arranged in the base to be visible on either side of the circuit board without departing from the invention.

The base 26 has a lower body 38 which is advantageously formed with a rectangular or other shape which facilitates manual handling and provides a finger grip for twisting the base 26 into place on the circuit board as will be described. The lower body 38 terminates in two semi-circular plane surfaces 40a, 40b. The plane surfaces 40a, 40b are substantially co-planar and their plane is normal to the axis indicated by the dashed line. As best seen in FIG. 2, when thus assembled, the conductors 18a, 18b lie upon the surfaces 40a, 40b. The conductors 18a, 18b may be affixed to the base 26 for example by adhesive means or heat sealing near the places where the conductors 18a, 18b approach the outer edges of the surfaces 40a, 40b, or alternatively the conductors 18a, 18b may be left unaffixed. The adhesive means may be electrically conductive. A shallow groove having a depth less than the diameter of the conductors 18a, 18b may be provided in the surfaces 40a, 40b to retain the conductors 18a, 18b against twisting during insertion.

Two outer semi-cylindrical leaves 42a, 42b are spaced away from the inner semi-cylindrical leaves 30a, 30b leaving annular relief spaces 44a, 44b between them. The upper portions of the outer semi-cylindrical leaves 42a, 42b are portions of a frusto-conal surface 46a, 46b. The frusto-conal surfaces 46a, 46b end in a lip 48a, 48b. Below the lips 48a, 48b, frusto-conal wedge surfaces 50a, 50b converge toward the axis and terminating in stem portions 52a, 52b. The stem portions 52a, 52b are partially undercut by mounting grooves 54a, 54b extending tangentially from the counterclockwise edge of the stem portions 52a, 52b as seen from above and terminating in a stop bar 56a, 56b (56a is hidden). The mounting grooves 54a, 54b have camming surfaces 58a, 58b which overlay the front surface of a circuit board as will be explained. The camming surfaces 58a, 58b having leading portions 60a (hidden) and 60b. The planes of the leading portions 60a, 60b are inclined to the axis in order to pull the base tightly into contact with the circuit board during insertion. The trailing portions 62a, 62b are more normal to the axis to securely hold the base against the circuit board 64. The circuit board 64 shown fragmentarily at the top of the exploded view has a hole 66 adapted to the insertion and locking of the based lamp. The hole 66 has a central generally circular portion 68 and two wings 70a, 70b. The base 26 with attached lamp 10 is inserted through the rear of the hole 66 with the inner semi-cylindrical leaves 30a, 30b and the outer semi-cylindrical leaves 42a, 42b passing through the wings 70a, 70b until the surfaces 40a, 40b come into contact with the rear of the circuit board 64. This brings the conductors 18a, 18 b into contact with metallic regions on the rear of the circuit board 64 through which electrical power may be fed.

To lock the lamp 10 and base 26 into the circuit board 64 the base is rotated clockwise, as seen from the bottom. As the base 26 begins to rotate, the inclined leading portions 60a, 60b are brought atop the circuit board adjacent to the circular portion 68 of the hole 66. With further rotation, the inclined leading portions 60a, 60b tend to bear the lamp base 26 more tightly against the circuit board 64. The relief spaces 44a, 44b allow the outer semi-cylindrical leaves 42a, 42b to deflect inward somewhat to produce a tight fit of the base 26 against the circuit board 64. Upon continued rotation, the trailing portions 62a, 62b of the camming surfaces 58a, 58b bear against the circuit board 64 and hold the base 26 firmly in place. Further rotation of the base 26 is stopped when the stop bars 56a, 56b (56a is hidden) contact the sides of the wings 70a, 70b. In attaining the condition just described, the lamp 10 and base 26 are fully installed with power being connected through conductive areas on the circuit board to the conductors 18a, 18b tightly held in contact with the back of the circuit board.

It will be understood that the claims are intended to cover all changes and modifications of the preferred embodiments of the invention, herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope of the invention.