US2321636A - Black-out lamp - Google Patents

Description

l June 15, 1943. J. P. TODD BLACK-OUT LAMP Filed Feb. 5, 1942 Juf 9 INVENTOR JBoYH/v IDH/L /P T000 ORNEYS Patented June 15, 1943 UNITED STATES PATENT YOFFICEv BLACK-OUT LAMP l.lohn Philip Todd, Mamaroneck, N. Y. Application February 5, 1942, SerialNo. 429,592

(Cl. 24o-108) 4 Claims.

In times of war, which involves the bombing -of Amunicipalities especially at -night by enemy aeroplanes ying overhead, it -becomes necessary as a defense measure to extinguish all lights by which the enemy aeroplane may be guided-and its target ascertained and this necessitates not only the Yextinguishment-of all -street and other outside lights but also either the extinguishment of lights within houses and other flouildings -or `the masking of all 'windows with opaque material to prevent the Aescape of light from .the inside. Such measures are known `as a blackout.

Since a complete .black-'out involves all the dangers 4attendant lupon the ymovement vof pedestrians and vehicles in total darknessfsuch as injuries resulting from collision, and is furthermore conducive -to crime, and since -th'e .masking of windows in homes, workshops and otheribu'ildings in orderfthat -lights may '-be used `therein so that those inside may move about with safety andeiciency', is an expensive and burdensome task, which it Ais-diiiicult to perform in the necessarily short space of time -available after warning has 'been received o'f lthefapproach -of enemy aeroplanes, lit is -one -f'of the vobjects of -niy linvention 4to provide Aa lamp whereby -fobjects in lthe immediate vicinity of lsuch lamp, 'for instance,

furniture in a room, may be suiiiciently 'illumir hatedto enable lone to seefand-m'oveabout without colliding .with said objects 'or furniture .and -yet from va short ldistance away Yfrom saidiflamp, such as, lfrom 'the street, 25 `or 30 feet 'distant from the Lhouse, the room appears through an open window to be, absolutely dark with nothing visible therein.

A further object of my invention is to provide a lamp in which the light proceeding therefrom is so thoroughly diffused that it forms no defined beam or cone. A still further object of my invention is to provide a lamp that consists of but few parts which may be readily assembled at small cost.

Other and further objects and advantages of my invention may be understood from the following description of it taken in connection with the appen-ded drawing in which Fig. 1 is a longitudinal cross-section of the lamp of my invention, and

Fig. 2 is a view on the line 2-2 of Fig. 1.

Referring to the drawing, Ill is a round shade of conical shape and preferably of a size about 31/2 inches in diameter at its bottom, about 21/2 inches in diameter at its top and about 6 inches in length. Said shade is open at the bottom `andclosed againstthe escape .of lig-htat the top. In the `topiis rigidly-mounted the lamp socket ZI I having a screw base -I'2 extending through fAthe top so that it 4is adaptable for insertion in the ordinary llamp socket.A Inserted lin thesocket III is a frosted lamp bulb I3 of a capacity of preferably about l'5'0 fwatts. The `inside surface of the shade I0 may be of bright metal or painted white orlotherw-ise treated to render-it light :re

iieCting.

Towards the .other.end .of saidshade isa circular screen SM. "Said .screen is preferably composed ro'flwirecloth having square'meshes-of Aabout .16.to the inch,.i.e..256ito the squareiinch.'

Immediately belowithescreen I4 and-surrounding the='innerrsurface ofthe-shade .lll .is a spacing ring I5 `about zone-.half inch 'in height .formed with a pluralityof closely .spaced inwardly pro- 'jectingtriangular tongues I6. Said tongues are each :formed -by cutting said .ring from the bottorn =alongone side IlI .of arigh't-angle .isosceles triangle andi-bending. said tongues'inwardly along the line .of lthefother side i8 of .said'triangle 'to the extent of about 45 .angular .displacement Ffrom :the surfaceof saidspacingring. 'The right angle of the said triangle constitutes its .iapex which is located about one-quartersof.v an inch `from :the .bottom of .said .spacing ring. Said vtongues iareimade -Iof bright :metal .or are otherwiseirendered flight frefl'e'cti'ng .on ftheirupper side. It :will be seen Lth'at'the-planes of .said tongues are vthus :disposed A:at :aan interior .angle :of 145 .to thefcro'ssfsectionalplane'of saidring.

Positioned .immediatelyibe'low said spacing ring I5 is a circular plate of thick translucent diffusive glass I9 of a color of relatively low visibility, preferably of a blue color, having an irregular surface and known as` cathedral blue streaked hammered pattern glass having an irregular wavy surface.

Positioned immediately below said glass is a round disc 20 perforated with a plurality of round holes 2| distributed substantially regularly over the surface thereof. I nd that holes having a diameter of about one-sixteenth of an inch and disposed at a frequency of about 25 to the square inch to be eminently satisfactory. Said disc may be flat but I nd that I get better results by having it dished inwardly as shown. Said disc is held within the shade I by the bent-over portions 22 of said shade and acts as a support for the glass I9, the spacing ring I5 and the screen I4 above it, or the said screen, tongues, glass and disc may be assembled and mounted within a circular frame with the said tongues occupying7 the same relative position intermediate the screen and the glass and held within the open end of the shade in any convenient manner.

It is to be understood that the screen, glass and disc completely lill the cross-sectional areas of the shade l at their respective levels so that no light proceeds from the shade except through the said screen, spacing ring, glass and disc, and are disposed at right angles to the axis of the shade I0.

Said tongues act as reflecting baiiles causing the rays which would otherwise strike the glass i9 adjacent its margin in a more or less perpendicular direction, to be reilected either away from said glass or to enter it at a wide angle of incidence, thus increasing the diffused character of the light emerging through the holes 2| in the disc and broadening the angular distribution of said diffused light. This may not be all the functions of the said tongues but I nd by experiment that with the tongues formed in the spacing ring I5 comprising part of the assembly as shown, the illumination of objects in a room is better and renders them more distinct than if such tongues were omitted, and at the same time their presence does not lessen the invisibility of those objects from the same distance outside the house. v

With a lamp of the size and characteristics above described hung from the center of the ceiling at a convenient height in a living-room 15 by feet in dimension, the said lamp furnishes sufcient light on a dark night to easily distinguish all objects in the room and, in fact, to read a newspaper close to and directly under it, while at a distance from 25 to 30 feet away on the outside the room appears as totally dark with no objects visible to a person loo-king'in through an open Window, and ,where there is no direct View of the disc 2U the lamp itself is also invisible.

The foregoing is a description 0f one embodiment of my invention, which is subject to changes and adaptations for other uses, for instance, automobile lights and street lighting, without departing from the spirit of my invention as defined in the appended claims.

What I claim is :l

l. Av lamp comprising an opaque shade, a lamp bulb mounted therein, means for filtering said light so as to permitl the passage therefrom of light of a color of low visibility only and for diffusing said light, a wire mesh screen positioned between and spaced apart from both said lamp bulb and said light diiusing and ltering means aaancc and a perforated disc positioned on the outside of said light diiusing and filtering means.

2. A black-out lamp comprising an opaque conical lampshade having one end open for the passage of light, a lamp bulb mounted in the other end of said shade, a wire cloth having 1G square meshes to the inch, a spacing ring formed with a plurality of inwardly projecting triangular tongues arranged close together about the inside circumference of said spacing ring, the surface of said tongues being light reecting and the plane of said tongues being disposed at an angle of substantially to the cross-sectional plane of said ring, a sheet of cathedral blue streaked hammered pattern glass and a disc formed with a plurality of small, closely spaced perforations therein, said Wire cloth, spacing ring, glass and disc being positioned within said shade in the order named adjacent the open end of said shade.

3. A lamp comprising an opaque lampshade having one end open for the passage of light, a lamp bulb mounted in the other end of said shade, a wire cloth having about 16 square meshes to the inch, a spacing ring formed with a plurality of inwardly projecting triangular tongues arranged close together about the inside circumference of said spacing ring, the surface of said tongues being light reflecting and the plane of said tongues being disposed at an angle of substantially 45 to the cross-sectio-nal plane of said ring, a sheet of cathedral blue streaked hammered pattern glass and a disc formed with a plurality of small, closely spaced perforations therein, said wire cloth, spacing ring, glass and disc being positioned Within said shade in the order named adjacent the open end of said shade.

4. A lamp comprising an opaque lampshade having one end open for the passage of light, a lamp bulb mounted in the other end of said shade, a Wire cloth having about 16 square meshes to the inch, a spacing ri-ng formed with a plurality of inwardly projecting triangular tongues arranged 'close together about the inside circumference of said spacing ring, the surface of said tongues being light reflecting and the plane of said tongues being disposedrat an angle of Substantially 45 to the cross-sectional plane of said ring, a sheet of translucent glass of a color of relatively low visibility and a disc formedV with a plurality of small, closely spaced perforations therein, said wire cloth, spacing ring, glass and disc being positioned within said shade in the order named adjacent the open end of said shade.

JOHN PHILIP TODD.

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