US2320424A - Fluorescent lamp - Google Patents

Description

June 1, 1943. J. E. GATES FLUORESCENT LAMP Filed March 19, 1941 Patented lane 1,' 1943 UNITED STATES PATENT orrlcs FLUORESCENT LAMP I .Feiferson E. Gates, Jacksonville, Fla.

- Application March 19, 1941, Serial No. 384,117).

1 Claim.

This invention relates to fluorescent lamps of that type which is adapted to be screwed into the conventional threaded light socket.

Fluorescent lamps have come into rather widespread use because of their superior illuminating qualities, as well as their low power consumption relative to the incandescent lamp. Such use has been largely confined to commercial and public establishments, rather than to private homes. lhis has been due to the expense of installation, as such lamps require special sockets, ballast in the form of transformers and the like, and other equipment. A further reason for the lack of popularity for home use is the fact that fluorescent lamps have been made in the form of tubes, these tubes varying in length in accordance with the output of the lamp.

The present invention. has for its object the provision of a fluorescent lamp provided with an adapter, whereby the lamp may be attached to the conventional light socket, the adapter housing the necessary ballast and starter units.

Another object of the invention is to provide such a lamp which may be readily secured to or removed from the adapter without removing the adapter from the socket in which it is threaded.

A further object of the invention is to provide a fluorescent lamp, in which the distance that the electrons must travel from one electrode to the-other is greatly reduced in proportion to the total amount of phosphor bearing surface area of the lamp, resulting in low brightness per unit area of surface and a high total light output with low power consumption.

A still further object of the invention is to provide such a lamp having an improved starting means to preheat the lamp electrodes to provide an abundance of free electrons, and to heat the mercury vapor within the lamp before and. after the high voltage starts normal lamp operation.

Other objects will appear as the following description of a preferred and practical embodiment of the invention proceeds.

Referring to the drawing:

Figure 1 is a vertical section illustrating the improved lamp and adapter;

Figure 2 is a horizontal section on the line 2--2 of Figure 1, illustrating the socket for receiving the lamp;

Figure 3 is a section on ure 1, showing the pins on the end of the lamp;

Figure ,4 is a wiring diagram of the circuit for controlling the lamp, in which the auxiliary heater switch is automatic; and

the line 3-3 of Fig- Figure 5 is a similar diagram, in which the auxiliary heater switch is manually controlled.

Referring to the drawing in detail, in Figure l is shown a fluorescent lamp having a glass bulb t of substantially globe shape. The bulb I is provided with a neck 2 having an annular shoulder 3 upon which is seated a disk 4 of suitable insulating material. The glass is molded over the top of the disk to securely position the disk in place.

The disk 4 forms a base upon which the interior elements of the lamp are supported, and also carries the base pins 5. Hollow glass tubes 6 extend from the disk 5 and support, at their lower ends, a second disk '5. Positive and negative electrodes 8 and 9 are fastened to the disks d and "l, respectively, and wires in connected to the base pins 5 extend through the tubes ii to supply current to the electrode 9.

The electrodes 8 and 9 are in the form of small rods of wire, coated with a material which has the property of freely emitting electrons when heated. The electrodes are secured upon the disks in circular form, and the electrons in passing from one electrode to the other will form a cylindrical curtain between the disks.

It can be readily seen that through the use of a globe-shaped bulb with the electrode arrangernent of the present invention, a great amount of surface area on the bulb is secured with only a relatively small distance between the electrodes. The less distance the electrons are required to bridge, the less power necessary to make the arc. The circular form of the electrodes, and the consequent cylindrical curtain of electrons produced thereby, will cause the mercury vapor within the bulb to activate a greater number of phosphors, with which the interior of the glass bulb is coated, than will the conventional relatively thin arc.

In order to adapt the lamp for use with present day light sockets, an adapter H is provided comprising a housing 52, preferably moulded from a plastic, and having a threaded plug I3 to fit a conventional light socket. The housing I2 is cup-shaped to receive a transformer 14 and a the mal switch control !5. Screws l6 hold the transformer within the housing- A skirt i1 is fastened to the underside of the transformer casing, and forms a socket to receive the base of the bulb. Bayonet slots l8 are provided in the skirt to receive pins l8 extending from the base of the bulb to lock the bulb in place in the adapter. A partition 20 separates the socket into two compartments and is provided with arcuate slots 2| to receive the base pins 501' the bulb. Se

2 cured to the partition m such position that the ends of the base pins I of the bulb will engage then! when the bulb is in place in the socket and the pins protrude through the slots 2|, are the spring contact fingers 22. The various wires from thetransformer and the thermal switch are connected to the spring contact fingers, and current is transmitted from the fingers to-the elements within the lamp bulb through the base pins 3. An apron 22' is secured to the housing and extends downward, its lower edge being in close proximity of the bulb, to give a finished appearance to the entire unit and to hide the socket and various connections when the bulb is the lamp electrodes a and a and the ballast ll which may be a high reactance transformer or reactor. This circuit is as follows: from the source of power through wire 25, ballast ll, wire 28, lamp electrode 8, wire 21, switch bi-metallic electrode 24, switch fixed electrode 23, wire 28.

lamp electrode 3, wire 28 to the opposite side of th 'powensupply. when voltage is applied to 'the circuit, no current flows except as a result of the glowdischarge between 'the two electrodes of the switch. A heating results which, by the expansion of the bi-metallic element, causes the electrodes to touch. This short circuiting of v the switch, which takes one or two seconds to be completed, allows a substantial flow of current to preheat the lamp electrodes. There'is enough residual heat in the switch to keep it closed for a short additional'time, a suitable period under normal conditions to preheat the lamp electrodes. With the opening of the switch, the resultant'high voltag surge starts normal lamp operation.

The switch does not again glow, since it is so designed that the remaining. available electrical potential is insufficient to cause a breakdown between the electrodes. This switch, and its op-' eration, is well known in the art, and is usually referred to as a glow switch."

Frequently, when fluorescent lamps areused out of doors in cold weather, the preheating of the lamp electrodes in the period of time allowed by the control switch is insufilcient to'warm the mercury vapor within th bulb and the arc fails to strike. To overcome this difllculty, the present invention provides a, small heating .coil 3ii, located within the bulb and receiving its current from a secondary winding 3| on the transformer H. The heating coil is controlled by the thermal control switch, and is connected thereto by means of an additional contact 32 and the following circuit: contact 32, wire 33, secondary coil 3|, wire 34,. heating coil 30, wire 21, and switch bi-metallic electrode 24.

when voltage is first applied, the bi-metailic electrode is in contact with the contact 32, and the heating coil is energizedto give an initial heating to the interior of the bulb. When the electrode 24 has moved from the contact 32 to make contact with the electrode 23 the circuit through the heating coil is broken. After the preheating of the lamp electrodes, the bi-metallic electrode 24 again makes contact'with 32 and the heating coil is again energized to maintain the temperature within the bulb to the point for most eificient operation of the lamp. A resistance 35 is tapped onto the heating coil circuit to prevent current build-up within the secondary coil and subsequent burning out of the coil.

The operation of the heating coil as described above, is entirely automatic, but in'Figure 5 is shown a. circuit employing a manually controlled heating coil. In this layout a manually operated switch 36 may be thrown to either thecontact 31 or the contact 38, and when theswitch is in contact with 31 the heating coil is in operation and the circuit is: switch 36, wire 39, secondary coil 3!, wire 40, wire 26, lamp electrode 8, wire 21, heating coil 30, wire 4|, and contact 31. When the switch arm 36 is in contact with 38,

the heating coil is no longer energized, but a circult is set up from switch arm 36 through wire 33, secondary coil 3|, resistance 42 to contact 38. This circuit is set up to prevent a build-up of the induced current in the coil 3|. It will-be readily understood that in this :form of the invention the heating coil operates continuously, so

long as the switch arm is in, contact with the contact 31. I

Whil I have in the above described preferred embodiments of the invention, the invention is not to be considered as limited to the forms shown and described, but only by the scope of through one side thereof, a plug carried by the housing for connection with the socket, a transformer including a secondary coil for energizing the heater in the lamp, said transformer also acting as a ballast, and a thermal control switch to control theoperation of said heater arranged in the chamber .pf the housing, a socket projecting from the transformer and exposed at the 7 open side of the housing and adapted to receive a part of the lamp when the adapter is connected with the lamp, said socket in the housing having locking means engageable with and disengagelamp.

JEFFERSON E. GATES.

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