BACKGROUND OF THE INVENTION Incandescent light bulbs are widely used in homes, offices, and businesses and are generally manually inserted into the appropriate socket. The conventional lightbulb has a glass envelope or globe, which protects the filament, and a base or cap portion affixed to the globe. The cap inclues a male thread that corresponds to a female thread on the inside of a socket in a light fixture. When properly inserted into the socket, the lightbulb is firmly held in place by the threads.

The current standards for the manufacture of such bases require, amongst other things, a sufficient number of turns of thread to ensure that the bulb is secure in the socket. Due to the limited amount of rotation of the wrist, it requires a number of repeated movements of grasping and turning to insert and secure or release and remove a bulb manufactured within these standards. Thus, it may be difficult to properly and quickly install a lightbulb because the cap of the bulb must be precisely aligned with the socket in order for the threads to properly join. This alignent may be particularly difficult for the elderly or disabled. Proper alignment also is difficult when installing lightbulbs into sockets located in high ceilings, or other hard to reach areas.

If the number of threads on the base of the bulb can be greatly reduced to leave a smooth cylindrical portion, starting at the end that is to be first inserted, then the bulb can be inserted in the socket and removed with fewer turns. The bayonet type bulb in current use accomplishes this but it cannot be used with a threaded socket.

The prior art for threaded bases contemplates a short unthreaded portion for the purpose of facilitating the alignment of the bulb within the socket. But, the number of threads must be greatly reduced to substantially reduce the amount of

turning. However, merely reducing the number of threads in order to reduce the amount of turning alone is not sufficient to provide an operable light bulb. This is because removal of most of the thread may result in a light bulb that is not stable or sufficiently secure in the light socket. Thus, an alternative must be provided in place of the missing thread, to secure the bulb base in the socket.

SUMMARY OF TIIE INVENTION The present invention is a lightbulb that can be installe in standard sockets, but has a partially smooth and partially threaded cap. This design allows the cap to be positioned in the socket properly before turning the lightbulb in the socket to join the threads. The lightbulb slips easily into the socket at the desired 90'angle and is less likely to misthread. Thus, lightbulbs in accordance with the present invention require less turns, thus less time to install and remove.

Also, because the cap contains fewer laps of thread than a standard cap, there are fewer laps to seize to the female threads in the socket. Thus, after a lightbulb has been in place for an extended amount of time, the cap is less likely to stick in position, thereby reducing the likelihood that the glass envelope will break during removal. If the glass envelope is broken, the reduced amount of thread laps allows for easier removal of the broken portion.

Without the present development, the thread portion remaining after the said removal would be insufficient to secure the base properly in the socket. Therefore, in place of the conventional full thread, this invention uses a minimum of thread, all or part of which has a thread variation which may include: 1) a gradual increase in thread width or"axial enlargement;" 2) a gradual increase in thread height or"radial enlargement;" 3) a combination of 1) and 2) or"overall enlargement;" 4) a variation in thread pitch; 5) any suitable thread feature that will increase the friction or pressure between the base and the socket; or 6) any combination of 1)-5). As a thread with axial enlargement is turned into the thread of the socket, the pressure along the radius of the thread increases against the socket wall. Similarly, with

radial enlargement, pressure between the sides of the thread and the female thread is increased. If both approches are combine, the result is a gradual overall enlargement of the thread. In this case, the outward pressure of the surface of the convex thread increases against the inner surface of the concave thread. Also, the pitch of the thread may be varied slightly so that at least some portion of the thread does not correspond to the thread in the socket. This mismatch will create an increase in pressure along the mismatched region.

In any case, the thread variation may start immediately or not until a lead-in portion of standard-sized, uniform thread is engaged in the thread of the socket.

The amount of thread before the commencement of the variation may be varied or eliminated as required to achieve the best result. The variation in the thread continues to the end of the thread near the bottom of the exposed glass of the bulb.

The effect of the thread variation is to cause a minor distortion of the metallic shell of the socket, pulling it tight against the base. The pressure together with the engagement of a short length of thread secures the base in the socket. This process is enhanced by the fact that standard electrical sockets are constructed of resilient soft flexible metal.

Also a portion or portions of broken thread may be used on the cylindrical (otherwise unthreaded) portion in conjunction with the expanding or enlarging thread to provide additional security. This portion or these portions are made small enough in radius and length of circumference to be slid axially into the socket with the smooth portion. Because the socket shell is constructed of a resilient flexible metal it can be slightly distorted to permit the seating of this portion of thread without turning.

Mass production in the manufacture of sockets and bases inevitably results in variations in size. Thus, the size of the thread at its commencement must fit within the minimum size for thread of a standard socket. Similarly, from an appropriate point, the thread variation must continue to increase until it is sufficient to effect the

necessary security in the case of the largest variation in the manufacture of the base and socket.

The variations in size of sockets and bases constructed within current maximum and minimum standards are relatively small. Accordingly, the difference in the amount of rotation required to secure a varied thread within these standards, is correspondingly small. As the difference between the amount of rotation is minimal, the difference in axial movement of the base in the socket is negligible.

This is significant because, though there is some tolerance, in each case the central electrode of the base must move axially to contact the central electrode of the socket.

More particularly, this invention provides, for use with a conventional light bulb socket having an internal thread: a light bulb base having a central electrode at one end thereof, a first substantially cylindrical outer wall portion adjacent said one end, and a second substantially cylindrical outer wall portion remote from said one end, said first outer wall portion being configure and sized such as to allow the base to be slid without rotation into a conventional socket, said second outer wall portion having an external thread adapted to engage said internal thread of a conventional socket, said external thread being of sufficient length, and enlarging along its length so as to cause increasing mechanical interference between the external thread and said internal thread as the light bulb is rotated during insertion, thus tending to distort the socket and causing a tight, secure grip between the socket and the light bulb base.

Additionally, this invention provides, for use with a conventional light bulb socket having an internal thread, a light bulb comprising: a globe, light-producing means within the globe, and a light bulb base secured to the globe, the base having a central electrode at an end thereof remote from the globe, a first substantially cylindrical outer wall portion adjacent said end, and a second substantially cylindrical outer wall portion

remote from said end, said first outer wall portion being configure and sized such as to allow the base to be slid without rotation into a conventional socket, said second outer wall portion having an external thread adapted to engage said internal thread of a conventional socket, said external thread undergoing an enlargement along its length so as to cause increasing mechanical interference between the external thread and said internal thread as the light bulb is rotated during insertion, thus tending to distort the socket and causing a tight, secure grip between the socket and the light bulb base.

In an alternate embodiment of the present invention, the thread may be unvaried in dimension and the desired securing force provided by a gasket or 0-ring positioned on the cap. The gasket is positioned so that it engages the socket when the bulb is installe in the socket. The friction between the gasket and the socket provides sufficient resistance to prevent inadvertent loosening of the light bulb from the socket.

In another alternate embodiment of the present invention, the outermost thread receiving area on the inner surface of the socket is replace with a smooth surface. This achieves the same result as the improved cap and functions with a standard lightbulb cap. The female threading of the socket may diminish in radius or width to provide the securing force described above. Alternatively, a gasket or 0-ring may be provided at the mouth of the socket or start of the female threads to provide the desired securing force.

Accordingly, it is the object of the present invention to provide a lightbulb with a cap that can easily and quickly be threaded into a socket.

Another object of the present invention is to provide a lightbulb with reduced threading for easy installation having a means for securing the lightbulb in the socket.

Other objects, features, and avantages of the present invention will become apparent with reference to the remainder of this document.

GENERAL DESCRIPTION OF THE DRAWINGS One embodiment and several variants of the invention are illustrated in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which: FIG. 1 is a side elevation of a standard light bulb, illustrating the prior art, also showing, in section, the configuration of a standard socket with which the standard light bulb is designed to be used. <BR> <BR> <BR> <BR> <BR> <P> FIG. 2 is a side elevation of an embodiment of the improved light bulb base.<BR> <BR> <BR> <BR> <BR> <BR> <BR> <P> FIG. 3 is an elevation of the light bulb base seen in FIG. 2;<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> FIG. 4 is a cross-sectional diagram a first embodiment of the invention.<BR> <BR> <BR> <BR> <BR> <BR> <BR> <P> FIG. 5 is a cross-sectional diagram of the of the embodiment of FIG. 4 showing the distortion of the socket wall caused by the asymmetry of the thread of the base after it is tightened in the socket; <BR> <BR> <BR> <BR> <BR> FIG. 6 is an elevation of a second embodiment of the invention.<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <P> FIG. 7 is a cross-section of the base taken along the line A-A in FIG. 6, showing the distortion of the circumference of the socket shell as the short length of thread passes a convex thread of the socket.

FIG. 8 is a cross-section of the base taken along the line A-A in FIG. 6, within the thread of the socket with the portion of thread on the base seated in the thread of the socket without distortion of the socket.

FIG. 9 is a side view of a third embodiment of the invention shown with a cross-sectional of a standard lightbulb socket.

FIG. 10 is a cross-section of the lightbulb of FIG. 9 properly inserted into a socket.

FIG. 11 is a cross-section of a fourth alternate embodiment of the present invention.

FIG. 12 is a partial side view of a lightbulb in accordance with the present invention.

FIGS. 12A/B are partial cross-sections of a first embodiment of the lightbulb of FIG. 12 taken along lines A and B.

FIGS. 13A/B are partial cross-sections of a second embodiment of the lightbulb of FIG. 12 taken along lines A and B.

FIGS. 14A/B are partial cross-sections of a third embodiment of the lightbulb of FIG. 12 taken along lines A and B.

FIG. 15 is a partial side view of a lightbulb in accordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation of the common incandescent light bulb currently widely used. It shows an opaque glass globe 1, the threaded base 2, the convex threads 3, the smooth inward turning portion 4, the insulation 5 of the central bottom electrode 6 and the central bottom electrode 6. It also shows, but in section, the metallic shell 7a of the socket with concave threads 7, into which the threaded base 2 is inserted, and the bottom electrode of the socket 8, insulated from the shell of the socket by the insulation 9.

FIG. 2 is an elevation of a similar bulb, but with the base as modifie in accordance with the invention. It shows an opaque glass globe 10, a metallic base 11, a short enlarging thread 12, a smooth inward curving portion 13, a central bottom electrode 15, insulation 14 for the central bottom electrode 15, and a substantially smooth and cylindrical unthreaded portion 16 of the base 11. The unthreaded portion 16 is sized to fit snugly but slidably within the socket threads 17.

The unthreaded portion 16 may include indented grooves or a series of indents 18, in accordance with the prior art, if necessary to help secure the internal structure of the bulb within the base.

FIG. 2 also shows, but in section, the metallic shell 7a of the socket with concave threads 19, in which the thread on the bulb base 12 is inserted, and the central electrode of the socket 20 insulated from the shell of the socket by insulation 21.

FIG. 3 is an enlarged elevation of an embodiment of the improved electrical base having a substantially smooth and cylindrical portion 22, with an enlarging thread 23 which encompasses (in the illustrated embodiment) more than one convolution of the base. The length of the thread 23 is not regarde as a limiting factor.

FIG. 3 also shows an indented groove 24 and a series of indents 25, any of which may be used, if required, to secure the internal structure in the base in accordance with the prior art. It also shows an inward curving smooth portion 26, insulation 27 for a central contact 28, and the central contact 28 itself.

FIG. 4 shows, in schematic cross-section, the circumference of a socket 29 (enlarged), with a projection 30 of the increasing circumference of the thread of the base (exaggerated), in an embodiment of the improved base having thread radii that increase.

FIG. 5 is a schematic cross-section showing, by the broken line (enlarged) 31, the unstressed circumference of the socket prior to insertion of the thread, along with a projection 32 of an exaggerated approximation of the distortion of the circumference of the socket caused by the circumference of the thread after insertion.

FIG. 6 is an elevation of an embodiment of the socket having, in addition to the expanding and enlarging thread 33, two short portions of thread 34 on the smooth cylindrical portion of the base.

FIG. 7 is a cross-section through the base taken along the line A-A in FIG. 6, showing the distortion (exaggerated) that is caused by the small portion of thread 35, as it passes a convex socket thread 36.

FIG. 8 is a similar cross-section of the base taken along the line A-A in FIG.

6, with the smooth portion of thread 35 seated within the concave circumference of the socket thread 38, when the socket has returned to its normal shape after the distortion illustrated in FIG. 7.

FIGS. 12-15 show four approches for varying thread 35 in order to secure the lightbulb in a socket. Thread variation which may include: As shown in FIG.

12A/B, a gradual increase in thread height X at point A to thread height X'at point B. As shown in FIG. 13A/B, a gradual increase in thread width Y at point A to thread width Y'at point B. As shown in FIG. 14A/B, the combination of a gradual increase in thread height X at point A to thread height X'at point B and a gradual increase in thread width Y at point A to thread width Y'at point B. As shown in Fig 15, a variation in thread pitch at point A to thread pitch 'at point B. Of course, any suitable thread feature that will increase the friction or pressure between the base and the socket, including any combination of these features, may be used to secure the lightbulb in the socket.

FIGS. 9 and 10 show a third alternate embodiment of lightbulb 50 in accordance with the present invention. Cap 52 is affixed to glass envelope 54 by conventional means. Cap 52 is divided into smooth portion 56 and threaded portion 58. Thread 60 runs around threaded portion 58 for about two laps. Smooth portion 56 has a length equal to about two laps of thread 60. Distal end 62 of cap 52 is inserted into opening 64 of lightbulb socket 66. Diameter 68 of smooth portion 56 of cap 52 is about 10 to 15 % less than diameter 70 of the interior of socket 66.

Smooth portion 56 of lightbulb cap 52 slides into socket 66. Cap 52 is inserted into socket 66 until thread 60 contacts interior wall 72 of socket 66.

Interior wall 72 of socket 66 is threaded to correspond to thread 60 on cap 52 of lightbulb 50. Turning lightbulb 50 clockwise causes thread 60 to mate with interior wall 72 of socket 66. Lightbulb 50 is turned clockwise until lightbulb 50 is securely fastened in socket 66.

Gasket 74 may be positioned around cap 52 above thread 60 to help secure lightbulb 50 into socket 66 when installe. Gasket 74 is positioned about cap 52 so that it seats within socket 66 when lightbulb 50 is installe in socket 66. Gasket 74 provides frictional resistance to rotation of lightbulb 50, thereby reducing the likelihood that lightbulb 50 will come loose from socket 66. Gasket 74 may be made of rubber, plastic or any other suitable material that will provide sufficient friction to prevent inadvertent loosening of lightbulb 50 from socket 66.

FIG. 3 shows an alternate embodiment of the present invention. Socket 100 has an interior wall 102. Distal portion 104 of socket 100 is smooth along wall 102.

Interior wall 102 of proximal portion 106 of socket 100 is threaded. A standard lightbulb 108 is inserted into the socket 100. The smooth interior distal portion 104 of socket 100 allows proper positioning of the cap of standard lightbulb 108.

Lightbulb 108 is inserted to threaded proximal portion 106, and then turned in a clockwise manner to secure lightbulb 108 into socket 100.

Gasket 110 may be positioned around near opening 114 of socket 100 to help secure lightbulb 108 in socket 100 when installe. Gasket 110 operates in the same manner as described above with respect to gasket 74. Alternatively, gasket 112 may be positioned within socket 100 proximate to threaded portion 106 to provide the same securing force.

This design is especially useful to the elderly and others with impaire manual dexterity because the smooth portion of the cap combine with fewer laps of thread allows the cap to be positioned properly in the socket and installe with minor effort. This design is also beneficial when using an extension pole to install lightbulbs in high ceilings. Thus, installation and maintenance is easier using this improved lightbulb design.

The foregoing is provided for purposes of illustration, explanation, and description of embodiments of the present invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of the invention.