US 1543606 A
Description (OCR text may contain errors)
June 23, 192 5. 1 1,543,606
W. HARRISON LIGHTING FIXTURE Filed Feb. 24, 1920 ,5 [ZVSZENTDR m map 5622231501? Hrs EPW032222:
Patented June 23, 1925.-
UNITED STATES PATENT OFFICE.
WARD HARRISON, or CLEVELAND, onro, ASSIGNOR T0 GENERAL ELECTRIC 001v:-
PANY, A CORPORATION OF NEW YORK.
. LIGHTING FIXTURE.
Application filed February 24, 1920. Serial No. 360,774.
To all whom it may concern:
Be it known that I, WARD HARRISON a citizen of the United States, residing at Cleveland, county of Cuyahoga, State of Ohio,-have invented certain new and useful Improvements in Lighting Fixtures, of which the following is a specification.
This invention relates to lighting units and pertains especially to units for semiindirect lighting.
The object of this fixture is to secure the recognized advantages of semi-indirect lighting, that is illumination in which the greaterpart of the lighting comes from large expansive ceilings, without its recognized disadvantages. The common way of securing such illumination, is to suspend an open bowl of opal glass below the ceiling and equip it with clear bulb incandescent lamps. The disadvantages of this plan are, first, that the open bowl and the exposed lamp collect interfere with the efiiciency of the unit Second, that with the concentrated filaments now commonly used in-incandescent lamps, the edge of the bowl throws a sharp shadow; on the ceiling or on the high side walls, which detracts from the appearance of the installation, and undesirable shadows of the chains or others supports for the fixture also appear. Several previous attempts or inventions have been made with the view to eliminating shadows but in all of these cases the result has been obtained only by a great sacrifice in the efliciency of the unit.
According to my invention, a unit is provided having two sections an upper section of which is clear glass and a lower section of translucent or semi-transparent glass. The clear section of the unithas. been made with a comparatively steep slope so that, so far as possible, the dust will slide off. Furthermore, there is but this one surface exposed, the lamp bulb itself and the interior of the unitbeing completely closed off. In ordinary fixtures about one-half of the loss is due to collection. of dust on the lamps themselves. The contour of the upper or clear section of the unit is so designed that all of the images of the filament reflected thereby are directed back into the bowl and, therefore, cannot reach the eye of the observer. In my first experiments the absence of this contour was productive of glare.
dust rapidly which seriously An embodiment of my invention is shown in the accompanying drawing in which Fig. 1 is a side elevation partially in sec tion of the main portion of my improved lighting unit and Fig. 2 is an assembled view of a complete unit.
Referring to the drawings, 10 represents a high efficiency tungsten lamp which is housed in my improved globe 11. The upper clear glass portion 12 of this is shown as being formed substantially on the surface of a sphere. This particular conformation has been designed for two purposes. First it prevents a reflected image of the filament becoming visible to those in the room as the ray lines 13 and 13 which are received from the light source 14 strike the globe at 15 and 15' and are redirected downwardly to the lower portion 16 of the globe 11 which is of semi-transparent reflecting material secured, for-instance, by coating with enamel or by the use of translucent glass. Second, no dust can accumulate on the clear glass portion due to its particular shape which allows the dust to roll off entirely or collect at the bottom which is translucent and where it will not affect the efiiciency of the unit.
Instead of having a sharp line of demarcation between the clear and enamelled sections of this fixture, I which has been characteristic of all previous uses of enamel in lighting glassware, the coating has been allowed to taper off gradually at 17 so there is no sharp line. Therefore, there is no objectionable shadow from the edge cast by the bowl against the side walls or ceiling. The chain shadows have been eliminated by suspending the unit from the neck rather than from the outside of the bowl. The neck 17 of the globe 11 must necessarily be of sufficient size to admit the lamp 10, hence the cap inclosing this opening would ordinarily ,cast a shadow on the ceiling which would be quite as objectionable as chain Shadows themselves. This difliculty has been overcome, however, bymaking a fixture 18 at its point of contact with the ceiling of substantially the diameter of the shadow cast by the cap. The boundaries of this shadow are shown by lines 19 which extend from the light source 20 to the outside of the canopy 21. Now when the unit is lighted, the .fixture simply appears of somewhat darker color than the ceiling ad M5 pleasing.
5 indirect bowl to enhance its appearance.
Those decorations or color tones ordinarily subtract very materially from the efiiciency of the light unit with the fixture described. Such results can be obtained with approxi- Ml mately no loss in efficiency by equipping the lamp with an opal cap 22 which cap reflects the large portion of the light to the ceiling and transmits simply enough light to render the globe luminous and The opal glass cap 22 is held in position by the coiled spring holder 23 which has extensions 24 fastened at 25 in the cap 22, the spring holder 23 fits over the neck of the lamp 10 and is under tension thus keeping the cap tightly around the lamp at all times.
What I claim as new and desire to secure by Letters Patent of the United States, is,
An integral inclosing globe for artificial light sources having its width greater than its depth and comprising a lower portion at least partially reflecting and extending below said light source, and an upper transparent portion having the contour of a portion of a sphere with its center at the light source extending over said light source.
In witness whereof, I have hereunto set my hand this 18th day or February, 1920.