Lamp and receptacle therefor

Dec. 28, 1943. w. w. garstang 2,337,745

LAMP AND RECEPTACLE THEREFOR

Filed July 26, 1941

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s WILLIAM W (MfcT/t/VCy

Patented Dec. 28, 1943

2,337,745

UNITED STATES PATENT OFFICE

2,337,745

LAMP AND RECEPTACLE THEREFOR

William W. Garstang, Indianapolis, Ind., assignor to Electronic Laboratories, Incorporated, Indianapolis, Ind., a corporation of Indiana

Application July 26, 1941, Serial No. 404,145

Claims. (Cl. 240—8.16)

The present invention relates to improvements in lamps and lamp holders.

More particularly, the invention relates to that type of lamp for emitting what has been commercially designated as a “black” light. 5

In certain types of illumination as, for instance, in cockpit illumination of airplanes and the like, it is desirable and in numerous instances, almost essential, that while the instruments be visible to the pilot, there be present in 10 the cockpit no apparent source of light. It has been found that light rays which would ordinarily not only illuminate the instruments but also illuminate the cockpit have a tendency to distort the pilot’s vision during night flying and 13 after he has been looking into darkness ahead for a considerable length of time. As a result of this condition, there has been developed a socalled “black” light through the medium of which the instrument indicators, which have been 20 colored with a fluorescent material, may be illuminated by ultra-violet or near ultra-violet rays developed by a lamp which ultra-violet or near ultra-violet rays are not visible to the eye.

The present invention relates to a lamp having 25 the above characteristics.

It has for one of its objects that of providing a compact lamp and lamp structure capable of emitting ultra-violet or near ultra-violet rays and provided with means for controlling the intensity 30 of these ray?.

For the purpose of disclosing the invention, certain embodiments thereof are illustrated in the accompanying drawing, in which

Fig. 1 is a longitudinal section of a casing em- 35 bodying my invention;

Fig. 2 is a longitudinal sectional view of the lamp bulb adapted to be fitted within said casing;

Fig. 3 is a side elevation of an intensity control shield adapted to surround the lamp illus- 40 trated in Fig. 2, the two then being , capable of assembly in the structure illustrated in Fig. 1;

Fig. 4 is a modification of a lamp tube adapted for use in the structure illustrated in Fig. 1;

Fig. 5 is a longitudinal sectional view of a mod- 45 ification of my invention;

Fig. 6 is a longitudinal view of the structure illustrated in Fig. 5; and

Fig. 7 is an elevation of the intensity controlling shutter. 50

Referring first to the structures illustrated in Figs. 1, 2 and 3, there is provided a tubular casing I which may be formed of metal, preferably being formed of aluminum, for lightness. This tubular casing I is provided on one side with a 55 cutout section or opening 2 which provides a view opening in the casing. Mounted within the casing i, at one end, is a hollow plug 3 which telescopes the end of the casing and makes a snug fit therein. This plug is provided with a hollow stem 4 screwthreaded on its exterior as at 5 to receive a supporting bracket 6 and the clamping nuts 7 and 8 for maintaining the bracket in position. The interior of the stem 4 is provided with an insulating bushing 9 and within this bushing is fitted a contact plug ! 0 having a spring contact 11 capable of making engagement with the conducting contact plug of the conducting wire and provided at its opposite end with a contact 12. The opposite end of the casing I is split longitudinally as at 13 to provide a series of spring fingers adapted to surround the cylindrical portion 14 of a rotatable cap having a closed end 15. This cap is provided with an annular groove 16 capable of receiving an annular bead 17 in the spring fingers formed at the end of the casing whereby when the cap is telescoped in position, it will be held against longitudinal displacement while permitting rotation thereof.

Removably mounted within the casing I is a secondary casing 18 formed of insulating material and having its ends closed by end caps 19 and

20. Contact studs 21 and 22 extend through these end caps, the stud 22 being adapted to contact the contact 12 and the stud 2 ί being adapted to make an electrical contact with the interior of the closure cap rotatably mounted on the casing, which casing may be grounded. This tubular member likewise is provided with an elongated slot or view opening 23 in one portion thereof and with a series of view openings 24—24 gradually diminishing in size.

Mounted within the casing 18 is a lamp comprising a bulb 25 with insulating end sleeves 26 and 27 and mounted within the end sleeve 27 is a starting switch 28. This lamp bulb 25 is of the fluorescent tube type. The glass of the bulb, however, is formed of material which, while permitting the passage therethrough of ultra-violet or near ultra-violet rays is impervious to the passage of visible light rays.

If desired, the interior of the glass bulb may be coated with a fluorescent material capable of regenerating the ultra-violet rays developed by the lamp and converting these ultra-violet rays into visible and near ultra-violet rays which near ultra-violet rays are invisible to the eye. However, due to the characteristic of the glass of which the bulb is formed, the near ultra-violet rays will be passed therethrough. The lamp bulb contains the usual quantity of mercury and the usual heaters 29—29 for heating or ionizing the mercury for the provision of a mercury arc to develop the ultra-violet rays. At each end of the lamp bulb, there is provided a pair of contacts, one of which at one end is connected with the contact 22 and the other of which, at the same end, is connected through a suitable conductor 39 with one terminal of the starter switch. The opposite terminal of this starter switch is connected to one contact, at the opposite end of the bulb and the other contact at the same end is connected to the terminal 21.

This bulb, as is illustrated in Fig. 2, is mounted within and rotatable with the insulating casing 18 which is preferably formed of material impervious to the passage of any light rays. This casing is provded with a lug 18' adapted to fit within an elongated slot 31 in the sleeve portion 14 of the cap so that the entire casing is capable of rotation with this cap. The contact 2 5, as before stated, makes contact with the cap and through the cap and casing I is grounded for the completion of the lamp circuit.

The above described structure thus provides a compact readily controlled lamp structure having means for readily controlling the intensity of the light rays developed thereby. It is obvious that when the slot 23 in the casing 88 coincides with the slot 2 in the casing 1, a maximum passage of the near ultra-violet rays developed by the lamp is permitted. For changing the intensity of the rays emitted by the lamp, the casing 18 may be rotated through the medium of the rotatable cap to cause the openings 24, of various sizes, to coincide with the slot 2 in the casing to thereby permit the passage of light rays of various intensity.

In Fig. 4, I have illustrated a modification of the structure wherein, instead of providing an enclosing casing, as 88, the lamp bulb itself may be constructed to provide the intensity control. •In this structure, the lamp bulb 25 may be coated with a material impervious to the passage of light rays of any character. Certain portions, however, of the lamp bulb may be left clear of this material so that the passage slot 25' of maximum area may be provided and other portions left clear as at 25” in the form of rows of openings of varying diameters to permit control of the intensity of the light rays, by the rotation of the bulb.

In Figs. 5, 6 and 7, there is illustrated a modification of the structure illustrated in Figs. 1, 2 and 3. In this structure, there is provided a cylindrical casing 32 having the elongated slotted opening 33. Within this casing is an end contact clip 34 and side contact clips 35, suitably insulated from one another by insulating material 38 and adapted to receive one end of a lamp having the same characteristics as the lamp bulb 25 with the exception that one contact of the lamp is a cylindrical cap 37 while the opposite contact is a pin 38. The opposite end of the casing is likewise provided with a side contact clip 39 adapted to embrace the opposite cap of the lamp and with an end contact clip 40 connected by a conductor 41 with the contact plug 42. This contact plug is fitted within and insulated from a metallic end closure 43 having a threaded stem 44 similar to the stem 4. In this lamp structure, a manually controlled starting switch 45 is provided. Surrounding the cylindrical casing 32 is a shutter casing 32' provided with a knurled end cap 46 and having a plurality

2,337,745 of elongated slots. The elongated slot 4Ϊ has substantially the same area as the elongated slot 33 in the casing, while the elongated slots 48, 49, etc., gradually narrow so that as the shutter is 5 rotated, a maximum amount of rays controllable to practically a minimum by the rotation of the shutter is permitted.